iio: adc: Add Renesas GyroADC driver

Add IIO driver for the Renesas RCar GyroADC block. This block is a simple 4/8-channel ADC which samples 12/15/24 bits of data every cycle from all channels.

Signed-off-by Marek Vasut <[email protected]>

Cc Geert Uytterhoeven <[email protected]>

Cc Simon Horman <[email protected]>

---
V2: - Spelling fixes
- Rename the driver source file to rcar-gyroadc
- Rework the channel sample width handling
- Use iio_device_claim_mode_direct()
- Rename "renesas,rcar-gyroadc" to "renesas,r8a7791-gyroadc" and rename "renesas,rcar-gyroadc-r8a7792" to "renesas,r8a7792-gyroadc" to match the new naming scheme (WARNING: scif uses the old one!)
- Switch to using regulators for channel voltage reference, add new properties renesas,gyroadc-vref-chN-supply for N in 0..7
- Handle vref regulators as optional to, make channels without vref regulator return EINVAL on read.
- Fix module license to GPL
- Drop interrupt.h include
- Rename clk to iclk
- Rename RCar to R-Car
- Rework the invalid mode handling
- Don't print error message on EPROBE_DEFER
- Drop fclk handling, use runtime PM for that instead
V3: - More R-Car spelling fixes
- Flip checks for V2H, since that's the only one that has interrupt registers
- Replace if-else statement with switch statement in init_mode
- Use unsigned types where applicable
- Rework timing calculation slightly to drop if-else block
- Use DIV_ROUND_CLOSEST
V4: - Add renesas,rcar-gyroadc fallback compatible string into the bindings
- Rework the ADC bindings to use per-channel subdevs
- Support more compatible ADC chips

---
 .../bindings/iio/adc/renesas,gyroadc.txt           |  70 +++
 MAINTAINERS                                        |   6 +
 drivers/iio/adc/Kconfig                            |  10 +
 drivers/iio/adc/Makefile                           |   1 +
 drivers/iio/adc/rcar-gyroadc.c                     | 531 +++++++++++++++++++++
 5 files changed, 618 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/iio/adc/renesas,gyroadc.txt
 create mode 100644 drivers/iio/adc/rcar-gyroadc.c

Documentation/devicetree/bindings/iio/adc/renesas,gyroadc.txt new file +8 -0

new file mode 100644
index 000000000000..2dcea9c8895b
@@ -0,0 +1,70 @@
+* Renesas RCar GyroADC device driver
+
+Required properties:
+- compatible:  Should be "renesas,<chip>-gyroadc", "renesas,rcar-gyroadc".
+               Use "renesas,r8a7792-gyroadc" for a GyroADC with interrupt
+               block found in R8A7792.
+- reg:         Address and length of the register set for the device
+- clocks:      References to all the clocks specified in the clock-names

Hi Marek,

Please CC linux-renesas-soc for drivers for (parts of) Renesas ARM SoCs.

Quoted 64 lines

Add IIO driver for the Renesas RCar GyroADC block. This block is a simple 4/8-channel ADC which samples 12/15/24 bits of data every cycle from all channels.

Signed-off-by Marek Vasut <[email protected]>

Cc Geert Uytterhoeven <[email protected]>

Cc Simon Horman <[email protected]>

---
V2: - Spelling fixes
- Rename the driver source file to rcar-gyroadc
- Rework the channel sample width handling
- Use iio_device_claim_mode_direct()
- Rename "renesas,rcar-gyroadc" to "renesas,r8a7791-gyroadc" and rename "renesas,rcar-gyroadc-r8a7792" to "renesas,r8a7792-gyroadc" to match the new naming scheme (WARNING: scif uses the old one!)
- Switch to using regulators for channel voltage reference, add new properties renesas,gyroadc-vref-chN-supply for N in 0..7
- Handle vref regulators as optional to, make channels without vref regulator return EINVAL on read.
- Fix module license to GPL
- Drop interrupt.h include
- Rename clk to iclk
- Rename RCar to R-Car
- Rework the invalid mode handling
- Don't print error message on EPROBE_DEFER
- Drop fclk handling, use runtime PM for that instead
V3: - More R-Car spelling fixes
- Flip checks for V2H, since that's the only one that has interrupt registers
- Replace if-else statement with switch statement in init_mode
- Use unsigned types where applicable
- Rework timing calculation slightly to drop if-else block
- Use DIV_ROUND_CLOSEST
V4: - Add renesas,rcar-gyroadc fallback compatible string into the bindings
- Rework the ADC bindings to use per-channel subdevs
- Support more compatible ADC chips

---
 .../bindings/iio/adc/renesas,gyroadc.txt           |  70 +++
 MAINTAINERS                                        |   6 +
 drivers/iio/adc/Kconfig                            |  10 +
 drivers/iio/adc/Makefile                           |   1 +
 drivers/iio/adc/rcar-gyroadc.c                     | 531 +++++++++++++++++++++
 5 files changed, 618 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/iio/adc/renesas,gyroadc.txt
 create mode 100644 drivers/iio/adc/rcar-gyroadc.c

Documentation/devicetree/bindings/iio/adc/renesas,gyroadc.txt new file +12 -0

new file mode 100644
index 000000000000..2dcea9c8895b
@@ -0,0 +1,70 @@
+* Renesas RCar GyroADC device driver
+
+Required properties:
+- compatible:  Should be "renesas,<chip>-gyroadc", "renesas,rcar-gyroadc".
+               Use "renesas,r8a7792-gyroadc" for a GyroADC with interrupt
+               block found in R8A7792.
+- reg:         Address and length of the register set for the device
+- clocks:      References to all the clocks specified in the clock-names
+               property as specified in
+               Documentation/devicetree/bindings/clock/clock-bindings.txt.
+- clock-names: Shall contain "fck" and "if". The "fck" is the GyroADC block
+               clock, the "if" is the interface clock.

Documentation/devicetree/bindings/iio/adc/renesas,gyroadc.txt line 18

Quoted 6 lines

Documentation/devicetree/bindings/iio/adc/renesas,gyroadc.txt new file +6 -0

+- power-domains: Must contain a reference to the PM domain, if available.
+- #address-cells: Should be <1> (setting for the subnodes)
+- #size-cells: Should be <0> (setting for the subnodes)
+
+Sub-nodes:
+Optionally you can define subnodes which define the reference voltage

which defined the connected ADC type and the reference voltage

Documentation/devicetree/bindings/iio/adc/renesas,gyroadc.txt line 19

Quoted 1 line

Documentation/devicetree/bindings/iio/adc/renesas,gyroadc.txt new file +1 -0

+for the analog inputs.

"channels", to match the wording below?

Quoted 4 lines

Documentation/devicetree/bindings/iio/adc/renesas,gyroadc.txt new file +4 -0

+
+Required properties for subnodes:
+- compatible:  Should be either of:
+               "fujitsu,mb88101a"

Documentation/devicetree/bindings/iio/adc/renesas,gyroadc.txt line 25

Quoted 2 lines

Documentation/devicetree/bindings/iio/adc/renesas,gyroadc.txt new file +2 -0

+                       - Fujitsu MB88101A compatible mode,
+                         12bit sampling, 4 channels

For this one, we have to find a better representation in DT. Unlike the other two types, the MB88101A is a 4-channel ADC, and thus only a single instance is supported, providing 4 channels.
Hence for MB88101A I suggest to just have a single node "adc", without a unit address or "reg" property.

Documentation/devicetree/bindings/iio/adc/renesas,gyroadc.txt line 28

Quoted 3 lines

Documentation/devicetree/bindings/iio/adc/renesas,gyroadc.txt new file +3 -0

+               "ti,adcs7476" or "ti,adc121" or "adi,ad7476"
+                       - TI ADCS7476 / TI ADC121 / ADI AD7476 compatible mode,
+                         15bit sampling, 8 channels

ADCS7476 are single channel ADCs.
"up to 8 channels can be connected"?

Quoted 11 lines

Documentation/devicetree/bindings/iio/adc/renesas,gyroadc.txt line 25

Quoted 5 lines

Documentation/devicetree/bindings/iio/adc/renesas,gyroadc.txt new file +5 -0

+Required properties for subnodes:
+- compatible:  Should be either of:
+               "fujitsu,mb88101a"
+                       - Fujitsu MB88101A compatible mode,
+                         12bit sampling, 4 channels

For this one, we have to find a better representation in DT. Unlike the other two types, the MB88101A is a 4-channel ADC, and thus only a single instance is supported, providing 4 channels.
Hence for MB88101A I suggest to just have a single node "adc", without a unit address or "reg" property.

Hmmmmmm, this doesn't look quite right and it does make the binding complicated and the MB88101A into quite the special snow flake. Also, what if you have the MB88101A channels 0 and 1 connected only to ie. gyroadc channels 2 and 3?

What about something like:

adc2: adc@2 {
reg = <0>;
compatible = "fujitsu,mb88101a";
vref-supply = <&vref_fujitsu_mb88101a>;
};

adc3: adc@3 {
reg = <3>;
renesas,adc-master = <&adc2>;
};

Hi Marek,

Quoted 12 lines · Marek Vasut

Quoted 11 lines

Documentation/devicetree/bindings/iio/adc/renesas,gyroadc.txt line 25

Quoted 5 lines

Documentation/devicetree/bindings/iio/adc/renesas,gyroadc.txt new file +5 -0

+Required properties for subnodes:
+- compatible:  Should be either of:
+               "fujitsu,mb88101a"
+                       - Fujitsu MB88101A compatible mode,
+                         12bit sampling, 4 channels

For this one, we have to find a better representation in DT. Unlike the other two types, the MB88101A is a 4-channel ADC, and thus only a single instance is supported, providing 4 channels.
Hence for MB88101A I suggest to just have a single node "adc", without a unit address or "reg" property.

Quoted 4 lines

Hmmmmmm, this doesn't look quite right and it does make the binding complicated and the MB88101A into quite the special snow flake. Also, what if you have the MB88101A channels 0 and 1 connected only to ie. gyroadc channels 2 and 3?

The gyroadc does not have multiple channel inputs, only a single input pin for serialized data. Supporting multiple channels is done using a 3-bit channel select (CHS) output signal.

In mode 1, the 2 lsb CHS lines are to be connected to the C[01] channel select pins on the MB88101A.
In other modes, I think you need an external multiplexer to select one of the 8 connected ADCs.

So while you cannot have non-standard channel wirings in mode 1, you can have a partial (or none at all) multiplexer and less than 8 ADCs, duplicating data to multiple channels.

Quoted 8 lines

What about something like:

adc2: adc@2 {
reg = <0>;
compatible = "fujitsu,mb88101a";
vref-supply = <&vref_fujitsu_mb88101a>;
};

Quoted 4 lines

adc3: adc@3 {
reg = <3>;
renesas,adc-master = <&adc2>;
};

Hmm, that can be used to describe duplicated channels, too ;-)

Quoted 13 lines · Geert Uytterhoeven

Quoted 12 lines · Marek Vasut

Quoted 11 lines

Documentation/devicetree/bindings/iio/adc/renesas,gyroadc.txt line 25

Quoted 5 lines

Documentation/devicetree/bindings/iio/adc/renesas,gyroadc.txt new file +5 -0

+Required properties for subnodes:
+- compatible:  Should be either of:
+               "fujitsu,mb88101a"
+                       - Fujitsu MB88101A compatible mode,
+                         12bit sampling, 4 channels

For this one, we have to find a better representation in DT. Unlike the other two types, the MB88101A is a 4-channel ADC, and thus only a single instance is supported, providing 4 channels.
Hence for MB88101A I suggest to just have a single node "adc", without a unit address or "reg" property.

Quoted 8 lines

Quoted 4 lines

Hmmmmmm, this doesn't look quite right and it does make the binding complicated and the MB88101A into quite the special snow flake. Also, what if you have the MB88101A channels 0 and 1 connected only to ie. gyroadc channels 2 and 3?

The gyroadc does not have multiple channel inputs, only a single input pin for serialized data. Supporting multiple channels is done using a 3-bit channel select (CHS) output signal.

Yep, it's kinda doing SPI behind the scenes.

Quoted 4 lines

In mode 1, the 2 lsb CHS lines are to be connected to the C[01] channel select pins on the MB88101A.
In other modes, I think you need an external multiplexer to select one of the 8 connected ADCs.

Yes.

Quoted 3 lines

So while you cannot have non-standard channel wirings in mode 1, you can have a partial (or none at all) multiplexer and less than 8 ADCs, duplicating data to multiple channels.

Right

Quoted 13 lines

Quoted 12 lines

What about something like:

adc2: adc@2 {
reg = <0>;
compatible = "fujitsu,mb88101a";
vref-supply = <&vref_fujitsu_mb88101a>;
};

adc3: adc@3 {
reg = <3>;
renesas,adc-master = <&adc2>;
};

Quoted 1 line

Hmm, that can be used to describe duplicated channels, too ;-)

So we go with this ? I'm not completely sure about the new "renesas,adc-master" property, are we OK with it ?

Hi Marek,

Quoted 53 lines · Marek Vasut

Quoted 13 lines · Geert Uytterhoeven

Quoted 12 lines · Marek Vasut

Quoted 11 lines

Documentation/devicetree/bindings/iio/adc/renesas,gyroadc.txt line 25

Quoted 5 lines

Documentation/devicetree/bindings/iio/adc/renesas,gyroadc.txt new file +5 -0

+Required properties for subnodes:
+- compatible:  Should be either of:
+               "fujitsu,mb88101a"
+                       - Fujitsu MB88101A compatible mode,
+                         12bit sampling, 4 channels

For this one, we have to find a better representation in DT. Unlike the other two types, the MB88101A is a 4-channel ADC, and thus only a single instance is supported, providing 4 channels.
Hence for MB88101A I suggest to just have a single node "adc", without a unit address or "reg" property.

Quoted 8 lines

Quoted 4 lines

Hmmmmmm, this doesn't look quite right and it does make the binding complicated and the MB88101A into quite the special snow flake. Also, what if you have the MB88101A channels 0 and 1 connected only to ie. gyroadc channels 2 and 3?

The gyroadc does not have multiple channel inputs, only a single input pin for serialized data. Supporting multiple channels is done using a 3-bit channel select (CHS) output signal.

Yep, it's kinda doing SPI behind the scenes.

Quoted 4 lines

In mode 1, the 2 lsb CHS lines are to be connected to the C[01] channel select pins on the MB88101A.
In other modes, I think you need an external multiplexer to select one of the 8 connected ADCs.

Yes.

Quoted 3 lines

So while you cannot have non-standard channel wirings in mode 1, you can have a partial (or none at all) multiplexer and less than 8 ADCs, duplicating data to multiple channels.

Right

Quoted 14 lines

Quoted 8 lines

What about something like:

adc2: adc@2 {
reg = <0>;
compatible = "fujitsu,mb88101a";
vref-supply = <&vref_fujitsu_mb88101a>;
};

Quoted 4 lines

adc3: adc@3 {
reg = <3>;
renesas,adc-master = <&adc2>;
};

Hmm, that can be used to describe duplicated channels, too ;-)

Quoted 2 lines

So we go with this ? I'm not completely sure about the new "renesas,adc-master" property, are we OK with it ?

I would still use just a single "adc" node for MB88101A, and multiple adc@n nodes (one for each physically present ADC) in other modes.

If someone really needs access to the higher scanning rate possible with duplicated channels, it can always be added later.

Add IIO driver for the Renesas RCar GyroADC block. This block is a simple 4/8-channel ADC which samples 12/15/24 bits of data every cycle from all channels.

Signed-off-by Marek Vasut <[email protected]>

Cc Geert Uytterhoeven <[email protected]>

Cc Simon Horman <[email protected]>

---
V2: - Spelling fixes
- Rename the driver source file to rcar-gyroadc
- Rework the channel sample width handling
- Use iio_device_claim_mode_direct()
- Rename "renesas,rcar-gyroadc" to "renesas,r8a7791-gyroadc" and rename "renesas,rcar-gyroadc-r8a7792" to "renesas,r8a7792-gyroadc" to match the new naming scheme (WARNING: scif uses the old one!)
- Switch to using regulators for channel voltage reference, add new properties renesas,gyroadc-vref-chN-supply for N in 0..7
- Handle vref regulators as optional to, make channels without vref regulator return EINVAL on read.
- Fix module license to GPL
- Drop interrupt.h include
- Rename clk to iclk
- Rename RCar to R-Car
- Rework the invalid mode handling
- Don't print error message on EPROBE_DEFER
- Drop fclk handling, use runtime PM for that instead
V3: - More R-Car spelling fixes
- Flip checks for V2H, since that's the only one that has interrupt registers
- Replace if-else statement with switch statement in init_mode
- Use unsigned types where applicable
- Rework timing calculation slightly to drop if-else block
- Use DIV_ROUND_CLOSEST
V4: - Add renesas,rcar-gyroadc fallback compatible string into the bindings
- Rework the ADC bindings to use per-channel subdevs
- Support more compatible ADC chips

---
 .../bindings/iio/adc/renesas,gyroadc.txt           |  70 +++
 MAINTAINERS                                        |   6 +
 drivers/iio/adc/Kconfig                            |  10 +
 drivers/iio/adc/Makefile                           |   1 +
 drivers/iio/adc/rcar-gyroadc.c                     | 531 +++++++++++++++++++++
 5 files changed, 618 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/iio/adc/renesas,gyroadc.txt
 create mode 100644 drivers/iio/adc/rcar-gyroadc.c

Documentation/devicetree/bindings/iio/adc/renesas,gyroadc.txt new file +21 -0

new file mode 100644
index 000000000000..2dcea9c8895b
@@ -0,0 +1,70 @@
+* Renesas RCar GyroADC device driver
+
+Required properties:
+- compatible:	Should be "renesas,<chip>-gyroadc", "renesas,rcar-gyroadc".
+		Use "renesas,r8a7792-gyroadc" for a GyroADC with interrupt
+		block found in R8A7792.
+- reg:		Address and length of the register set for the device
+- clocks:	References to all the clocks specified in the clock-names
+		property as specified in
+		Documentation/devicetree/bindings/clock/clock-bindings.txt.
+- clock-names:	Shall contain "fck" and "if". The "fck" is the GyroADC block
+		clock, the "if" is the interface clock.
+- power-domains: Must contain a reference to the PM domain, if available.
+- #address-cells: Should be <1> (setting for the subnodes)
+- #size-cells:	Should be <0> (setting for the subnodes)
+
+Sub-nodes:
+Optionally you can define subnodes which define the reference voltage
+for the analog inputs.
+
+Required properties for subnodes:

Documentation/devicetree/bindings/iio/adc/renesas,gyroadc.txt new file +39 -0

+- reg:		Should be the number of the analog input.
+- vref-supply:	Reference to the channel reference voltage regulator.
+
+Example:
+	vref_max1162: regulator-vref-max1162 {
+		compatible = "regulator-fixed";
+
+		regulator-name = "MAX1162 Vref";
+		regulator-min-microvolt = <4096000>;
+		regulator-max-microvolt = <4096000>;
+	};
+
+	&adc {
+		compatible = "renesas,r8a7791-gyroadc", "renesas,rcar-gyroadc";
+		reg = <0 0xe6e54000 0 64>;
+		clocks = <&mstp9_clks R8A7791_CLK_GYROADC>, <&clk_65m>;
+		clock-names = "fck", "if";
+		power-domains = <&sysc R8A7791_PD_ALWAYS_ON>;
+
+		pinctrl-0 = <&adc_pins>;
+		pinctrl-names = "default";
+
+		status = "okay";
+
+		#address-cells = <1>;
+		#size-cells = <0>;
+
+		adc@0 {
+			reg = <0>;
+			compatible = "maxim,max1162";
+			vref-supply = <&vref_max1162>;
+		};
+
+		adc@1 {
+			reg = <1>;
+			compatible = "maxim,max1162";
+			vref-supply = <&vref_max1162>;
+		};
+	};

MAINTAINERS +6 -0

index 890fc9e3c191..498e8a755eb6 100644
@@ -10276,6 +10276,12 @@ L:	[email protected]
 F:	drivers/net/ethernet/renesas/
 F:	include/linux/sh_eth.h
 
+RENESAS R-CAR GYROADC DRIVER
+M:	Marek Vasut <[email protected]>
+L:	[email protected]
+S:	Supported
+F:	drivers/iio/adc/rcar_gyro_adc.c
+
 RENESAS USB2 PHY DRIVER
 M:	Yoshihiro Shimoda <[email protected]>
 L:	[email protected]

drivers/iio/adc/Kconfig +0 -0

index 99c051490eff..f9954c71048d 100644

drivers/iio/adc/Kconfig +4 -0

+
+	  To compile this driver as a module, choose M here: the
+	  module will be called rcar-gyroadc.
+
 config ROCKCHIP_SARADC
 	tristate "Rockchip SARADC driver"
 	depends on ARCH_ROCKCHIP || (ARM && COMPILE_TEST)

drivers/iio/adc/Makefile +1 -0

index 7a40c04c311f..13db7c2bffc8 100644
@@ -39,6 +39,7 @@ obj-$(CONFIG_NAU7802) += nau7802.o
 obj-$(CONFIG_PALMAS_GPADC) += palmas_gpadc.o
 obj-$(CONFIG_QCOM_SPMI_IADC) += qcom-spmi-iadc.o
 obj-$(CONFIG_QCOM_SPMI_VADC) += qcom-spmi-vadc.o
+obj-$(CONFIG_RCAR_GYRO_ADC) += rcar-gyroadc.o
 obj-$(CONFIG_ROCKCHIP_SARADC) += rockchip_saradc.o
 obj-$(CONFIG_STX104) += stx104.o
 obj-$(CONFIG_TI_ADC081C) += ti-adc081c.o

drivers/iio/adc/rcar-gyroadc.c new file +93 -0

new file mode 100644
index 000000000000..14f139613e1c
@@ -0,0 +1,531 @@
+/*
+ * Renesas R-Car GyroADC driver
+ *
+ * Copyright 2016 Marek Vasut <[email protected]>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/delay.h>
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/io.h>
+#include <linux/clk.h>
+#include <linux/of.h>
+#include <linux/of_irq.h>
+#include <linux/regulator/consumer.h>
+#include <linux/of_platform.h>
+#include <linux/err.h>
+#include <linux/pm_runtime.h>
+
+#include <linux/iio/iio.h>
+#include <linux/iio/buffer.h>
+#include <linux/iio/sysfs.h>
+#include <linux/iio/trigger.h>
+
+/* GyroADC registers. */
+#define RCAR_GYROADC_MODE_SELECT		0x00
+#define RCAR_GYROADC_MODE_SELECT_1_MB88101A	0x0
+#define RCAR_GYROADC_MODE_SELECT_2_ADCS7476	0x1
+#define RCAR_GYROADC_MODE_SELECT_3_MAX1162	0x3
+
+#define RCAR_GYROADC_START_STOP			0x04
+#define RCAR_GYROADC_START_STOP_START		BIT(0)
+
+#define RCAR_GYROADC_CLOCK_LENGTH		0x08
+#define RCAR_GYROADC_1_25MS_LENGTH		0x0c
+
+#define RCAR_GYROADC_REALTIME_DATA(ch)		(0x10 + ((ch) * 4))
+#define RCAR_GYROADC_100MS_ADDED_DATA(ch)	(0x30 + ((ch) * 4))
+#define RCAR_GYROADC_10MS_AVG_DATA(ch)		(0x50 + ((ch) * 4))
+
+#define RCAR_GYROADC_FIFO_STATUS		0x70
+#define RCAR_GYROADC_FIFO_STATUS_EMPTY(ch)	BIT(0 + (4 * (ch)))
+#define RCAR_GYROADC_FIFO_STATUS_FULL(ch)	BIT(1 + (4 * (ch)))
+#define RCAR_GYROADC_FIFO_STATUS_ERROR(ch)	BIT(2 + (4 * (ch)))
+
+#define RCAR_GYROADC_INTR			0x74
+#define RCAR_GYROADC_INTR_INT			BIT(0)
+
+#define RCAR_GYROADC_INTENR			0x78
+#define RCAR_GYROADC_INTENR_INTEN		BIT(0)
+
+#define RCAR_GYROADC_SAMPLE_RATE		800	/* Hz */
+
+enum rcar_gyroadc_model {
+	RCAR_GYROADC_MODEL_DEFAULT,
+	RCAR_GYROADC_MODEL_R8A7792,
+};
+
+struct rcar_gyroadc {
+	struct device			*dev;
+	void __iomem			*regs;
+	struct clk			*iclk;
+	struct regulator		*vref[8];
+	unsigned int			num_channels;
+	enum rcar_gyroadc_model		model;
+	unsigned int			mode;
+	unsigned int			sample_width;
+	u32				buffer[8];
+};
+
+static void rcar_gyroadc_hw_init(struct rcar_gyroadc *priv)
+{
+	const unsigned long clk_mhz = clk_get_rate(priv->iclk) / 1000000;
+	const unsigned long clk_mul =
+		(priv->mode == RCAR_GYROADC_MODE_SELECT_1_MB88101A) ? 10 : 5;
+
+	/* Stop the GyroADC. */
+	writel(0, priv->regs + RCAR_GYROADC_START_STOP);
+
+	/* Disable IRQ on V2H. */
+	if (priv->model == RCAR_GYROADC_MODEL_R8A7792)
+		writel(0, priv->regs + RCAR_GYROADC_INTENR);

drivers/iio/adc/rcar-gyroadc.c new file +28 -0

+	 */
+	writel(RCAR_GYROADC_START_STOP_START,
+	       priv->regs + RCAR_GYROADC_START_STOP);
+
+	/* Wait for the first conversion to complete. */
+	udelay(1250);
+}
+
+#define RCAR_GYROADC_CHAN(_idx) {				\
+	.type			= IIO_VOLTAGE,			\
+	.indexed		= 1,				\
+	.channel		= (_idx),			\
+	.info_mask_separate	= BIT(IIO_CHAN_INFO_RAW) |	\
+				  BIT(IIO_CHAN_INFO_SCALE),	\
+	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SAMP_FREQ), \
+}
+
+static const struct iio_chan_spec rcar_gyroadc_iio_channels_1[] = {
+	RCAR_GYROADC_CHAN(0),
+	RCAR_GYROADC_CHAN(1),
+	RCAR_GYROADC_CHAN(2),
+	RCAR_GYROADC_CHAN(3),
+};
+
+static const struct iio_chan_spec rcar_gyroadc_iio_channels_2[] = {
+	RCAR_GYROADC_CHAN(0),
+	RCAR_GYROADC_CHAN(1),
+	RCAR_GYROADC_CHAN(2),

drivers/iio/adc/rcar-gyroadc.c new file +39 -0

+ */
+static const struct iio_chan_spec rcar_gyroadc_iio_channels_3[] = {
+	RCAR_GYROADC_CHAN(0),
+	RCAR_GYROADC_CHAN(1),
+	RCAR_GYROADC_CHAN(2),
+	RCAR_GYROADC_CHAN(3),
+	RCAR_GYROADC_CHAN(4),
+	RCAR_GYROADC_CHAN(5),
+	RCAR_GYROADC_CHAN(6),
+	RCAR_GYROADC_CHAN(7),
+};
+
+static int rcar_gyroadc_read_raw(struct iio_dev *indio_dev,
+				 struct iio_chan_spec const *chan,
+				 int *val, int *val2, long mask)
+{
+	struct rcar_gyroadc *priv = iio_priv(indio_dev);
+	struct regulator *consumer = priv->vref[chan->channel];
+	unsigned int datareg = RCAR_GYROADC_REALTIME_DATA(chan->channel);
+	unsigned int vref;
+	int ret;
+
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW:
+		if (chan->type != IIO_VOLTAGE)
+			return -EINVAL;
+
+		/* Channel not connected. */
+		if (!consumer)
+			return -EINVAL;
+
+		ret = iio_device_claim_direct_mode(indio_dev);
+		if (ret)
+			return ret;
+
+		*val = readl(priv->regs + datareg);
+		*val &= BIT(priv->sample_width) - 1;
+
+		iio_device_release_direct_mode(indio_dev);

drivers/iio/adc/rcar-gyroadc.c new file +94 -0

+		return IIO_VAL_INT_PLUS_NANO;
+	case IIO_CHAN_INFO_SAMP_FREQ:
+		*val = RCAR_GYROADC_SAMPLE_RATE;
+		return IIO_VAL_INT;
+	default:
+		return -EINVAL;
+	}
+}
+
+static int rcar_gyroadc_reg_access(struct iio_dev *indio_dev,
+				   unsigned int reg, unsigned int writeval,
+				   unsigned int *readval)
+{
+	struct rcar_gyroadc *priv = iio_priv(indio_dev);
+	unsigned int maxreg = RCAR_GYROADC_FIFO_STATUS;
+
+	if (readval == NULL)
+		return -EINVAL;
+
+	if (reg % 4)
+		return -EINVAL;
+
+	/* Handle the V2H case with extra interrupt block. */
+	if (priv->model == RCAR_GYROADC_MODEL_R8A7792)
+		maxreg = RCAR_GYROADC_INTENR;
+
+	if (reg > maxreg)
+		return -EINVAL;
+
+	*readval = readl(priv->regs + reg);
+
+	return 0;
+}
+
+static const struct iio_info rcar_gyroadc_iio_info = {
+	.driver_module		= THIS_MODULE,
+	.read_raw		= rcar_gyroadc_read_raw,
+	.debugfs_reg_access	= rcar_gyroadc_reg_access,
+};
+
+static const struct of_device_id rcar_gyroadc_match[] = {
+	{
+		/* R-Car compatible GyroADC */
+		.compatible	= "renesas,rcar-gyroadc",
+		.data		= (void *)RCAR_GYROADC_MODEL_DEFAULT,
+	}, {
+		/* R-Car V2H specialty with interrupt registers. */
+		.compatible	= "renesas,r8a7792-gyroadc",
+		.data		= (void *)RCAR_GYROADC_MODEL_R8A7792,
+	}, {
+		/* sentinel */
+	}
+};
+
+MODULE_DEVICE_TABLE(of, rcar_gyroadc_match);
+
+static const struct of_device_id rcar_gyroadc_child_match[] = {
+	/* Mode 1 ADCs */
+	{
+		.compatible	= "fujitsu,mb88101a",
+		.data		= (void *)RCAR_GYROADC_MODE_SELECT_1_MB88101A,
+	},
+	/* Mode 2 ADCs */
+	{
+		.compatible	= "ti,adcs7476",
+		.data		= (void *)RCAR_GYROADC_MODE_SELECT_2_ADCS7476,
+	}, {
+		.compatible	= "ti,adc121",
+		.data		= (void *)RCAR_GYROADC_MODE_SELECT_2_ADCS7476,
+	}, {
+		.compatible	= "adi,ad7476",
+		.data		= (void *)RCAR_GYROADC_MODE_SELECT_2_ADCS7476,
+	},
+	/* Mode 3 ADCs */
+	{
+		.compatible	= "maxim,max1162",
+		.data		= (void *)RCAR_GYROADC_MODE_SELECT_3_MAX1162,
+	}, {
+		.compatible	= "maxim,max11100",
+		.data		= (void *)RCAR_GYROADC_MODE_SELECT_3_MAX1162,
+	},
+	{ /* sentinel */ }
+};
+
+static int rcar_gyroadc_parse_subdevs(struct iio_dev *indio_dev)
+{
+	const struct of_device_id *of_id;
+	const struct iio_chan_spec *channels;
+	struct rcar_gyroadc *priv = iio_priv(indio_dev);
+	struct device *dev = priv->dev;
+	struct device_node *np = dev->of_node;
+	struct device_node *child;
+	struct regulator *vref;
+	unsigned int reg, maxreg;

drivers/iio/adc/rcar-gyroadc.c new file +37 -0

+			continue;
+		}
+
+		ret = of_property_read_u32(child, "reg", &reg);
+		if (ret) {
+			dev_err(dev,
+				"Failed to get child reg property of ADC \"%s\".\n",
+				child->name);
+			continue;
+		}
+
+		childmode = (unsigned int)of_id->data;
+		switch (childmode) {
+		case RCAR_GYROADC_MODE_SELECT_1_MB88101A:
+			maxreg = 4;
+			sample_width = 12;
+			channels = rcar_gyroadc_iio_channels_1;
+			num_channels = ARRAY_SIZE(rcar_gyroadc_iio_channels_1);
+			break;
+		case RCAR_GYROADC_MODE_SELECT_2_ADCS7476:
+			maxreg = 8;
+			sample_width = 15;
+			channels = rcar_gyroadc_iio_channels_2;
+			num_channels = ARRAY_SIZE(rcar_gyroadc_iio_channels_2);
+			break;
+		case RCAR_GYROADC_MODE_SELECT_3_MAX1162:
+			maxreg = 8;
+			sample_width = 16;
+			channels = rcar_gyroadc_iio_channels_3;
+			num_channels = ARRAY_SIZE(rcar_gyroadc_iio_channels_3);
+			break;
+		}
+
+		/* Channel number is too high. */
+		if (reg >= maxreg) {
+			dev_err(dev,
+				"Only %i channels supported with %s, but reg = <%i>, ignoring.\n",

drivers/iio/adc/rcar-gyroadc.c new file +117 -0

+			continue;
+		}
+
+		priv->vref[reg] = vref;
+
+		if (!first)
+			continue;
+
+		/* First child node which passed sanity tests. */
+		adcmode = childmode;
+		first = 0;
+
+		priv->num_channels = maxreg;
+		priv->mode = childmode;
+		priv->sample_width = sample_width;
+
+		indio_dev->channels = channels;
+		indio_dev->num_channels = num_channels;
+	}
+
+	if (first) {
+		dev_err(dev, "No valid ADC channels found, aborting.\n");
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static void rcar_gyroadc_deinit_supplies(struct iio_dev *indio_dev)
+{
+	struct rcar_gyroadc *priv = iio_priv(indio_dev);
+	unsigned int i;
+
+	for (i = 0; i < priv->num_channels; i++) {
+		if (!priv->vref[i])
+			continue;
+
+		regulator_disable(priv->vref[i]);
+	}
+}
+
+static int rcar_gyroadc_init_supplies(struct iio_dev *indio_dev)
+{
+	struct rcar_gyroadc *priv = iio_priv(indio_dev);
+	struct device *dev = priv->dev;
+	unsigned int i;
+	int ret;
+
+	for (i = 0; i < priv->num_channels; i++) {
+		if (!priv->vref[i])
+			continue;
+
+		ret = regulator_enable(priv->vref[i]);
+		if (ret) {
+			dev_err(dev, "Failed to enable regulator %i (ret=%i)\n",
+				i, ret);
+			goto err;
+		}
+	}
+
+	return 0;
+
+err:
+	rcar_gyroadc_deinit_supplies(indio_dev);
+	return ret;
+}
+
+static int rcar_gyroadc_probe(struct platform_device *pdev)
+{
+	const struct of_device_id *of_id =
+		of_match_device(rcar_gyroadc_match, &pdev->dev);
+	struct device *dev = &pdev->dev;
+	struct rcar_gyroadc *priv;
+	struct iio_dev *indio_dev;
+	struct resource *mem;
+	int ret;
+
+	indio_dev = devm_iio_device_alloc(dev, sizeof(*priv));
+	if (!indio_dev) {
+		dev_err(dev, "Failed to allocate IIO device.\n");
+		return -ENOMEM;
+	}
+
+	priv = iio_priv(indio_dev);
+	priv->dev = dev;
+
+	mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	priv->regs = devm_ioremap_resource(dev, mem);
+	if (IS_ERR(priv->regs))
+		return PTR_ERR(priv->regs);
+
+	priv->iclk = devm_clk_get(dev, "if");
+	if (IS_ERR(priv->iclk)) {
+		ret = PTR_ERR(priv->iclk);
+		if (ret != -EPROBE_DEFER)
+			dev_err(dev, "Failed to get IF clock (ret=%i)\n", ret);
+		return ret;
+	}
+
+	ret = rcar_gyroadc_parse_subdevs(indio_dev);
+	if (ret)
+		return ret;
+
+	ret = rcar_gyroadc_init_supplies(indio_dev);
+	if (ret)
+		return ret;
+
+	priv->model = (enum rcar_gyroadc_model)of_id->data;
+
+	platform_set_drvdata(pdev, indio_dev);
+
+	indio_dev->name = dev_name(dev);
+	indio_dev->dev.parent = dev;
+	indio_dev->dev.of_node = pdev->dev.of_node;
+	indio_dev->info = &rcar_gyroadc_iio_info;
+	indio_dev->modes = INDIO_DIRECT_MODE;
+

drivers/iio/adc/rcar-gyroadc.c new file +15 -0

+
+	ret = iio_device_register(indio_dev);
+	if (ret) {
+		dev_err(dev, "Couldn't register IIO device.\n");
+		goto error_iio_device_register;
+	}
+
+	return 0;
+
+error_iio_device_register:
+	clk_disable_unprepare(priv->iclk);
+error_clk_if_enable:
+	pm_runtime_put(dev);
+	pm_runtime_disable(dev);
+	rcar_gyroadc_deinit_supplies(indio_dev);

drivers/iio/adc/rcar-gyroadc.c new file +25 -0

+	writel(0, priv->regs + RCAR_GYROADC_START_STOP);
 
+
+	iio_device_unregister(indio_dev);
+	clk_disable_unprepare(priv->iclk);
+	pm_runtime_put(dev);
+	pm_runtime_disable(dev);
+	rcar_gyroadc_deinit_supplies(indio_dev);
+
+	return 0;
+}
+
+static struct platform_driver rcar_gyroadc_driver = {
+	.probe          = rcar_gyroadc_probe,
+	.remove         = rcar_gyroadc_remove,
+	.driver         = {
+		.name		= "rcar-gyroadc",
+		.of_match_table	= rcar_gyroadc_match,
+	},
+};
+
+module_platform_driver(rcar_gyroadc_driver);
+
+MODULE_AUTHOR("Marek Vasut <[email protected]>");
+MODULE_DESCRIPTION("Renesas R-Car GyroADC driver");
+MODULE_LICENSE("GPL");

Quoted 7 lines · Marek Vasut

Add IIO driver for the Renesas RCar GyroADC block. This block is a simple 4/8-channel ADC which samples 12/15/24 bits of data every cycle from all channels.

Signed-off-by Marek Vasut <[email protected]>

Cc Geert Uytterhoeven <[email protected]>

Cc Simon Horman <[email protected]>

Various minor bits and pieces. In particular I'm not keen on carrying on probing once we have a device tree entry that is 'wrong'. I'd bail there and then. This should never happen an is a bug.

The only obvious exception would be if the device name wasn't supported 'yet'. Things to do with how it is described should result in hard errors.

Anyhow, basically looks pretty good.

Jonathan

Quoted 73 lines

---
V2: - Spelling fixes
- Rename the driver source file to rcar-gyroadc
- Rework the channel sample width handling
- Use iio_device_claim_mode_direct()
- Rename "renesas,rcar-gyroadc" to "renesas,r8a7791-gyroadc" and rename "renesas,rcar-gyroadc-r8a7792" to "renesas,r8a7792-gyroadc" to match the new naming scheme (WARNING: scif uses the old one!)
- Switch to using regulators for channel voltage reference, add new properties renesas,gyroadc-vref-chN-supply for N in 0..7
- Handle vref regulators as optional to, make channels without vref regulator return EINVAL on read.
- Fix module license to GPL
- Drop interrupt.h include
- Rename clk to iclk
- Rename RCar to R-Car
- Rework the invalid mode handling
- Don't print error message on EPROBE_DEFER
- Drop fclk handling, use runtime PM for that instead
V3: - More R-Car spelling fixes
- Flip checks for V2H, since that's the only one that has interrupt registers
- Replace if-else statement with switch statement in init_mode
- Use unsigned types where applicable
- Rework timing calculation slightly to drop if-else block
- Use DIV_ROUND_CLOSEST
V4: - Add renesas,rcar-gyroadc fallback compatible string into the bindings
- Rework the ADC bindings to use per-channel subdevs
- Support more compatible ADC chips

---
 .../bindings/iio/adc/renesas,gyroadc.txt           |  70 +++
 MAINTAINERS                                        |   6 +
 drivers/iio/adc/Kconfig                            |  10 +
 drivers/iio/adc/Makefile                           |   1 +
 drivers/iio/adc/rcar-gyroadc.c                     | 531 +++++++++++++++++++++
 5 files changed, 618 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/iio/adc/renesas,gyroadc.txt
 create mode 100644 drivers/iio/adc/rcar-gyroadc.c

Documentation/devicetree/bindings/iio/adc/renesas,gyroadc.txt new file +28 -0

new file mode 100644
index 000000000000..2dcea9c8895b
@@ -0,0 +1,70 @@
+* Renesas RCar GyroADC device driver
+
+Required properties:
+- compatible:	Should be "renesas,<chip>-gyroadc", "renesas,rcar-gyroadc".
+		Use "renesas,r8a7792-gyroadc" for a GyroADC with interrupt
+		block found in R8A7792.
+- reg:		Address and length of the register set for the device
+- clocks:	References to all the clocks specified in the clock-names
+		property as specified in
+		Documentation/devicetree/bindings/clock/clock-bindings.txt.
+- clock-names:	Shall contain "fck" and "if". The "fck" is the GyroADC block
+		clock, the "if" is the interface clock.
+- power-domains: Must contain a reference to the PM domain, if available.
+- #address-cells: Should be <1> (setting for the subnodes)
+- #size-cells:	Should be <0> (setting for the subnodes)
+
+Sub-nodes:
+Optionally you can define subnodes which define the reference voltage
+for the analog inputs.
+
+Required properties for subnodes:
+- compatible:	Should be either of:
+		"fujitsu,mb88101a"
+			- Fujitsu MB88101A compatible mode,
+			  12bit sampling, 4 channels
+		"ti,adcs7476" or "ti,adc121" or "adi,ad7476"
+			- TI ADCS7476 / TI ADC121 / ADI AD7476 compatible mode,
+			  15bit sampling, 8 channels

Documentation/devicetree/bindings/iio/adc/renesas,gyroadc.txt line 31

Quoted 3 lines

Documentation/devicetree/bindings/iio/adc/renesas,gyroadc.txt new file +3 -0

+		"maxim,max1162" or "maxim,max11100"
+			- Maxim MAX1162 / Maxim MAX11100 compatible mode,
+			  16bit sampling, 8 channels

Worth putting something here about how this might be interfaced. Realistically we are either looking at some extra circuitry or supporting only 3 of the channels.
The max11100 is only a single channel device for example. This description doesn't make it clear that 8 of them would be needed to do 8 channels.

Quoted 64 lines

Documentation/devicetree/bindings/iio/adc/renesas,gyroadc.txt new file +39 -0

+- reg:		Should be the number of the analog input.
+- vref-supply:	Reference to the channel reference voltage regulator.
+
+Example:
+	vref_max1162: regulator-vref-max1162 {
+		compatible = "regulator-fixed";
+
+		regulator-name = "MAX1162 Vref";
+		regulator-min-microvolt = <4096000>;
+		regulator-max-microvolt = <4096000>;
+	};
+
+	&adc {
+		compatible = "renesas,r8a7791-gyroadc", "renesas,rcar-gyroadc";
+		reg = <0 0xe6e54000 0 64>;
+		clocks = <&mstp9_clks R8A7791_CLK_GYROADC>, <&clk_65m>;
+		clock-names = "fck", "if";
+		power-domains = <&sysc R8A7791_PD_ALWAYS_ON>;
+
+		pinctrl-0 = <&adc_pins>;
+		pinctrl-names = "default";
+
+		status = "okay";
+
+		#address-cells = <1>;
+		#size-cells = <0>;
+
+		adc@0 {
+			reg = <0>;
+			compatible = "maxim,max1162";
+			vref-supply = <&vref_max1162>;
+		};
+
+		adc@1 {
+			reg = <1>;
+			compatible = "maxim,max1162";
+			vref-supply = <&vref_max1162>;
+		};
+	};

MAINTAINERS +6 -0

index 890fc9e3c191..498e8a755eb6 100644
@@ -10276,6 +10276,12 @@ L:	[email protected]
 F:	drivers/net/ethernet/renesas/
 F:	include/linux/sh_eth.h
 
+RENESAS R-CAR GYROADC DRIVER
+M:	Marek Vasut <[email protected]>
+L:	[email protected]
+S:	Supported
+F:	drivers/iio/adc/rcar_gyro_adc.c
+
 RENESAS USB2 PHY DRIVER
 M:	Yoshihiro Shimoda <[email protected]>
 L:	[email protected]

drivers/iio/adc/Kconfig +0 -0

index 99c051490eff..f9954c71048d 100644
@@ -408,6 +408,16 @@ config QCOM_SPMI_VADC
 	  To compile this driver as a module, choose M here: the module will
 	  be called qcom-spmi-vadc.
 

drivers/iio/adc/Kconfig config QCOM_SPMI_VADC · line 416

Quoted 6 lines

drivers/iio/adc/Kconfig +6 -0

+config RCAR_GYRO_ADC
+	tristate "Renesas R-Car GyroADC driver"
+	depends on ARCH_RCAR_GEN2 || (ARM && COMPILE_TEST)
+	help
+	  Say yes here to build support for the GyroADC found in Renesas
+	  R-Car Gen2 SoCs.

Put a bit more detail here perhaps - it's not really an ADC afterall but a rather dumb spi offload engine.

supporting it through that infrastructure. That would require changes in every relevant driver though so not terribly elegant.

Quoted 122 lines

drivers/iio/adc/Kconfig +4 -0

+
+	  To compile this driver as a module, choose M here: the
+	  module will be called rcar-gyroadc.
+
 config ROCKCHIP_SARADC
 	tristate "Rockchip SARADC driver"
 	depends on ARCH_ROCKCHIP || (ARM && COMPILE_TEST)

drivers/iio/adc/Makefile +1 -0

index 7a40c04c311f..13db7c2bffc8 100644
@@ -39,6 +39,7 @@ obj-$(CONFIG_NAU7802) += nau7802.o
 obj-$(CONFIG_PALMAS_GPADC) += palmas_gpadc.o
 obj-$(CONFIG_QCOM_SPMI_IADC) += qcom-spmi-iadc.o
 obj-$(CONFIG_QCOM_SPMI_VADC) += qcom-spmi-vadc.o
+obj-$(CONFIG_RCAR_GYRO_ADC) += rcar-gyroadc.o
 obj-$(CONFIG_ROCKCHIP_SARADC) += rockchip_saradc.o
 obj-$(CONFIG_STX104) += stx104.o
 obj-$(CONFIG_TI_ADC081C) += ti-adc081c.o

drivers/iio/adc/rcar-gyroadc.c new file +97 -0

new file mode 100644
index 000000000000..14f139613e1c
@@ -0,0 +1,531 @@
+/*
+ * Renesas R-Car GyroADC driver
+ *
+ * Copyright 2016 Marek Vasut <[email protected]>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/delay.h>
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/io.h>
+#include <linux/clk.h>
+#include <linux/of.h>
+#include <linux/of_irq.h>
+#include <linux/regulator/consumer.h>
+#include <linux/of_platform.h>
+#include <linux/err.h>
+#include <linux/pm_runtime.h>
+
+#include <linux/iio/iio.h>
+#include <linux/iio/buffer.h>
+#include <linux/iio/sysfs.h>
+#include <linux/iio/trigger.h>
+
+/* GyroADC registers. */
+#define RCAR_GYROADC_MODE_SELECT		0x00
+#define RCAR_GYROADC_MODE_SELECT_1_MB88101A	0x0
+#define RCAR_GYROADC_MODE_SELECT_2_ADCS7476	0x1
+#define RCAR_GYROADC_MODE_SELECT_3_MAX1162	0x3
+
+#define RCAR_GYROADC_START_STOP			0x04
+#define RCAR_GYROADC_START_STOP_START		BIT(0)
+
+#define RCAR_GYROADC_CLOCK_LENGTH		0x08
+#define RCAR_GYROADC_1_25MS_LENGTH		0x0c
+
+#define RCAR_GYROADC_REALTIME_DATA(ch)		(0x10 + ((ch) * 4))
+#define RCAR_GYROADC_100MS_ADDED_DATA(ch)	(0x30 + ((ch) * 4))
+#define RCAR_GYROADC_10MS_AVG_DATA(ch)		(0x50 + ((ch) * 4))
+
+#define RCAR_GYROADC_FIFO_STATUS		0x70
+#define RCAR_GYROADC_FIFO_STATUS_EMPTY(ch)	BIT(0 + (4 * (ch)))
+#define RCAR_GYROADC_FIFO_STATUS_FULL(ch)	BIT(1 + (4 * (ch)))
+#define RCAR_GYROADC_FIFO_STATUS_ERROR(ch)	BIT(2 + (4 * (ch)))
+
+#define RCAR_GYROADC_INTR			0x74
+#define RCAR_GYROADC_INTR_INT			BIT(0)
+
+#define RCAR_GYROADC_INTENR			0x78
+#define RCAR_GYROADC_INTENR_INTEN		BIT(0)
+
+#define RCAR_GYROADC_SAMPLE_RATE		800	/* Hz */
+
+enum rcar_gyroadc_model {
+	RCAR_GYROADC_MODEL_DEFAULT,
+	RCAR_GYROADC_MODEL_R8A7792,
+};
+
+struct rcar_gyroadc {
+	struct device			*dev;
+	void __iomem			*regs;
+	struct clk			*iclk;
+	struct regulator		*vref[8];
+	unsigned int			num_channels;
+	enum rcar_gyroadc_model		model;
+	unsigned int			mode;
+	unsigned int			sample_width;
+	u32				buffer[8];
+};
+
+static void rcar_gyroadc_hw_init(struct rcar_gyroadc *priv)
+{
+	const unsigned long clk_mhz = clk_get_rate(priv->iclk) / 1000000;
+	const unsigned long clk_mul =
+		(priv->mode == RCAR_GYROADC_MODE_SELECT_1_MB88101A) ? 10 : 5;
+
+	/* Stop the GyroADC. */
+	writel(0, priv->regs + RCAR_GYROADC_START_STOP);
+
+	/* Disable IRQ on V2H. */
+	if (priv->model == RCAR_GYROADC_MODEL_R8A7792)
+		writel(0, priv->regs + RCAR_GYROADC_INTENR);
+
+	/* Set mode and timing. */
+	writel(priv->mode, priv->regs + RCAR_GYROADC_MODE_SELECT);
+	writel(clk_mhz * clk_mul, priv->regs + RCAR_GYROADC_CLOCK_LENGTH);

drivers/iio/adc/rcar-gyroadc.c line 103

Quoted 6 lines

drivers/iio/adc/rcar-gyroadc.c new file +6 -0

+	writel(clk_mhz * 1250, priv->regs + RCAR_GYROADC_1_25MS_LENGTH);
+
+	/*
+	 * We can possibly turn the sampling on/off on-demand to reduce power
+	 * consumption, but for the sake of quick availability of samples, we
+	 * don't do it now.

Typically, if you want to do this, do it with runtime_pm and use the auto suspend stuff. Can work well.

Quoted 32 lines

drivers/iio/adc/rcar-gyroadc.c new file +32 -0

+	 */
+	writel(RCAR_GYROADC_START_STOP_START,
+	       priv->regs + RCAR_GYROADC_START_STOP);
+
+	/* Wait for the first conversion to complete. */
+	udelay(1250);
+}
+
+#define RCAR_GYROADC_CHAN(_idx) {				\
+	.type			= IIO_VOLTAGE,			\
+	.indexed		= 1,				\
+	.channel		= (_idx),			\
+	.info_mask_separate	= BIT(IIO_CHAN_INFO_RAW) |	\
+				  BIT(IIO_CHAN_INFO_SCALE),	\
+	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SAMP_FREQ), \
+}
+
+static const struct iio_chan_spec rcar_gyroadc_iio_channels_1[] = {
+	RCAR_GYROADC_CHAN(0),
+	RCAR_GYROADC_CHAN(1),
+	RCAR_GYROADC_CHAN(2),
+	RCAR_GYROADC_CHAN(3),
+};
+
+static const struct iio_chan_spec rcar_gyroadc_iio_channels_2[] = {
+	RCAR_GYROADC_CHAN(0),
+	RCAR_GYROADC_CHAN(1),
+	RCAR_GYROADC_CHAN(2),
+	RCAR_GYROADC_CHAN(3),
+	RCAR_GYROADC_CHAN(4),
+	RCAR_GYROADC_CHAN(5),
+	RCAR_GYROADC_CHAN(6),

drivers/iio/adc/rcar-gyroadc.c line 141

Quoted 6 lines

drivers/iio/adc/rcar-gyroadc.c new file +6 -0

+	RCAR_GYROADC_CHAN(7),
+};
+
+/*
+ * NOTE: The data we receive in mode 3 from MAX1162 have MSByte = 0,
+ *       therefore we only use 16bit realbits here instead of 24.

Umm. That would be a fair comment if realbits was set at all! With what you are currently supporting it shouldn't be.

Quoted 43 lines

drivers/iio/adc/rcar-gyroadc.c new file +43 -0

+ */
+static const struct iio_chan_spec rcar_gyroadc_iio_channels_3[] = {
+	RCAR_GYROADC_CHAN(0),
+	RCAR_GYROADC_CHAN(1),
+	RCAR_GYROADC_CHAN(2),
+	RCAR_GYROADC_CHAN(3),
+	RCAR_GYROADC_CHAN(4),
+	RCAR_GYROADC_CHAN(5),
+	RCAR_GYROADC_CHAN(6),
+	RCAR_GYROADC_CHAN(7),
+};
+
+static int rcar_gyroadc_read_raw(struct iio_dev *indio_dev,
+				 struct iio_chan_spec const *chan,
+				 int *val, int *val2, long mask)
+{
+	struct rcar_gyroadc *priv = iio_priv(indio_dev);
+	struct regulator *consumer = priv->vref[chan->channel];
+	unsigned int datareg = RCAR_GYROADC_REALTIME_DATA(chan->channel);
+	unsigned int vref;
+	int ret;
+
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW:
+		if (chan->type != IIO_VOLTAGE)
+			return -EINVAL;
+
+		/* Channel not connected. */
+		if (!consumer)
+			return -EINVAL;
+
+		ret = iio_device_claim_direct_mode(indio_dev);
+		if (ret)
+			return ret;
+
+		*val = readl(priv->regs + datareg);
+		*val &= BIT(priv->sample_width) - 1;
+
+		iio_device_release_direct_mode(indio_dev);
+
+		return IIO_VAL_INT;
+	case IIO_CHAN_INFO_SCALE:
+		/* Channel not connected. */

drivers/iio/adc/rcar-gyroadc.c line 190

Quoted 6 lines

drivers/iio/adc/rcar-gyroadc.c new file +6 -0

+		if (!consumer)
+			return -EINVAL;
+
+		vref = regulator_get_voltage(consumer);
+		*val = 0;
+		*val2 = DIV_ROUND_CLOSEST(vref * 1000, 0x10000);

spacing is a bit variable. Sometimes you leave a line before the return, sometimes you don't. Pick one or the other and it'll read slightly better!

Quoted 94 lines

drivers/iio/adc/rcar-gyroadc.c new file +94 -0

+		return IIO_VAL_INT_PLUS_NANO;
+	case IIO_CHAN_INFO_SAMP_FREQ:
+		*val = RCAR_GYROADC_SAMPLE_RATE;
+		return IIO_VAL_INT;
+	default:
+		return -EINVAL;
+	}
+}
+
+static int rcar_gyroadc_reg_access(struct iio_dev *indio_dev,
+				   unsigned int reg, unsigned int writeval,
+				   unsigned int *readval)
+{
+	struct rcar_gyroadc *priv = iio_priv(indio_dev);
+	unsigned int maxreg = RCAR_GYROADC_FIFO_STATUS;
+
+	if (readval == NULL)
+		return -EINVAL;
+
+	if (reg % 4)
+		return -EINVAL;
+
+	/* Handle the V2H case with extra interrupt block. */
+	if (priv->model == RCAR_GYROADC_MODEL_R8A7792)
+		maxreg = RCAR_GYROADC_INTENR;
+
+	if (reg > maxreg)
+		return -EINVAL;
+
+	*readval = readl(priv->regs + reg);
+
+	return 0;
+}
+
+static const struct iio_info rcar_gyroadc_iio_info = {
+	.driver_module		= THIS_MODULE,
+	.read_raw		= rcar_gyroadc_read_raw,
+	.debugfs_reg_access	= rcar_gyroadc_reg_access,
+};
+
+static const struct of_device_id rcar_gyroadc_match[] = {
+	{
+		/* R-Car compatible GyroADC */
+		.compatible	= "renesas,rcar-gyroadc",
+		.data		= (void *)RCAR_GYROADC_MODEL_DEFAULT,
+	}, {
+		/* R-Car V2H specialty with interrupt registers. */
+		.compatible	= "renesas,r8a7792-gyroadc",
+		.data		= (void *)RCAR_GYROADC_MODEL_R8A7792,
+	}, {
+		/* sentinel */
+	}
+};
+
+MODULE_DEVICE_TABLE(of, rcar_gyroadc_match);
+
+static const struct of_device_id rcar_gyroadc_child_match[] = {
+	/* Mode 1 ADCs */
+	{
+		.compatible	= "fujitsu,mb88101a",
+		.data		= (void *)RCAR_GYROADC_MODE_SELECT_1_MB88101A,
+	},
+	/* Mode 2 ADCs */
+	{
+		.compatible	= "ti,adcs7476",
+		.data		= (void *)RCAR_GYROADC_MODE_SELECT_2_ADCS7476,
+	}, {
+		.compatible	= "ti,adc121",
+		.data		= (void *)RCAR_GYROADC_MODE_SELECT_2_ADCS7476,
+	}, {
+		.compatible	= "adi,ad7476",
+		.data		= (void *)RCAR_GYROADC_MODE_SELECT_2_ADCS7476,
+	},
+	/* Mode 3 ADCs */
+	{
+		.compatible	= "maxim,max1162",
+		.data		= (void *)RCAR_GYROADC_MODE_SELECT_3_MAX1162,
+	}, {
+		.compatible	= "maxim,max11100",
+		.data		= (void *)RCAR_GYROADC_MODE_SELECT_3_MAX1162,
+	},
+	{ /* sentinel */ }
+};
+
+static int rcar_gyroadc_parse_subdevs(struct iio_dev *indio_dev)
+{
+	const struct of_device_id *of_id;
+	const struct iio_chan_spec *channels;
+	struct rcar_gyroadc *priv = iio_priv(indio_dev);
+	struct device *dev = priv->dev;
+	struct device_node *np = dev->of_node;
+	struct device_node *child;
+	struct regulator *vref;
+	unsigned int reg, maxreg;

drivers/iio/adc/rcar-gyroadc.c line 294

Quoted 10 lines

drivers/iio/adc/rcar-gyroadc.c new file +10 -0

+	unsigned int adcmode, childmode;
+	unsigned int sample_width;
+	unsigned int num_channels;
+	int ret, first = 1;
+
+	for_each_child_of_node(np, child) {
+		of_id = of_match_node(rcar_gyroadc_child_match, child);
+		if (!of_id) {
+			dev_err(dev, "Ignoring unsupported ADC \"%s\".",
+				child->name);

This is the only case that should result in a continue.

Quoted 37 lines

drivers/iio/adc/rcar-gyroadc.c new file +37 -0

+			continue;
+		}
+
+		ret = of_property_read_u32(child, "reg", &reg);
+		if (ret) {
+			dev_err(dev,
+				"Failed to get child reg property of ADC \"%s\".\n",
+				child->name);
+			continue;
+		}
+
+		childmode = (unsigned int)of_id->data;
+		switch (childmode) {
+		case RCAR_GYROADC_MODE_SELECT_1_MB88101A:
+			maxreg = 4;
+			sample_width = 12;
+			channels = rcar_gyroadc_iio_channels_1;
+			num_channels = ARRAY_SIZE(rcar_gyroadc_iio_channels_1);
+			break;
+		case RCAR_GYROADC_MODE_SELECT_2_ADCS7476:
+			maxreg = 8;
+			sample_width = 15;
+			channels = rcar_gyroadc_iio_channels_2;
+			num_channels = ARRAY_SIZE(rcar_gyroadc_iio_channels_2);
+			break;
+		case RCAR_GYROADC_MODE_SELECT_3_MAX1162:
+			maxreg = 8;
+			sample_width = 16;
+			channels = rcar_gyroadc_iio_channels_3;
+			num_channels = ARRAY_SIZE(rcar_gyroadc_iio_channels_3);
+			break;
+		}
+
+		/* Channel number is too high. */
+		if (reg >= maxreg) {
+			dev_err(dev,
+				"Only %i channels supported with %s, but reg = <%i>, ignoring.\n",

drivers/iio/adc/rcar-gyroadc.c line 341

Quoted 10 lines

drivers/iio/adc/rcar-gyroadc.c new file +10 -0

+				maxreg, child->name, reg);
+			continue;
+		}
+
+		/* Child node selected different mode than the rest. */
+		if (!first && (adcmode != childmode)) {
+			dev_err(dev,
+				"Channel %i uses different ADC mode than the rest, ignoring.\n",
+				reg);
+			continue;

Fail hard - not softly - I'd expect the probe to completely fail if the device tree is invalid in this way.

Same is true for other conditions above. Don't paper over the issue please.

Quoted 7 lines

drivers/iio/adc/rcar-gyroadc.c new file +7 -0

+		}
+
+		/* Channel is valid, grab the regulator. */
+		dev->of_node = child;
+		vref = devm_regulator_get_optional(dev, "vref");
+		dev->of_node = np;
+		if (IS_ERR(vref)) {

drivers/iio/adc/rcar-gyroadc.c line 354

Quoted 6 lines

drivers/iio/adc/rcar-gyroadc.c new file +6 -0

+			/*
+			 * Regulator is not present, which means the channel
+			 * supply is not connected.
+			 */
+			dev_dbg(dev, "Channel %i 'vref' supply not connected\n",
+				reg);

Error out rather than carrying on to try other channels. If the device tree is invalid we want to know and fail hard.

Quoted 121 lines

drivers/iio/adc/rcar-gyroadc.c new file +121 -0

+			continue;
+		}
+
+		priv->vref[reg] = vref;
+
+		if (!first)
+			continue;
+
+		/* First child node which passed sanity tests. */
+		adcmode = childmode;
+		first = 0;
+
+		priv->num_channels = maxreg;
+		priv->mode = childmode;
+		priv->sample_width = sample_width;
+
+		indio_dev->channels = channels;
+		indio_dev->num_channels = num_channels;
+	}
+
+	if (first) {
+		dev_err(dev, "No valid ADC channels found, aborting.\n");
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static void rcar_gyroadc_deinit_supplies(struct iio_dev *indio_dev)
+{
+	struct rcar_gyroadc *priv = iio_priv(indio_dev);
+	unsigned int i;
+
+	for (i = 0; i < priv->num_channels; i++) {
+		if (!priv->vref[i])
+			continue;
+
+		regulator_disable(priv->vref[i]);
+	}
+}
+
+static int rcar_gyroadc_init_supplies(struct iio_dev *indio_dev)
+{
+	struct rcar_gyroadc *priv = iio_priv(indio_dev);
+	struct device *dev = priv->dev;
+	unsigned int i;
+	int ret;
+
+	for (i = 0; i < priv->num_channels; i++) {
+		if (!priv->vref[i])
+			continue;
+
+		ret = regulator_enable(priv->vref[i]);
+		if (ret) {
+			dev_err(dev, "Failed to enable regulator %i (ret=%i)\n",
+				i, ret);
+			goto err;
+		}
+	}
+
+	return 0;
+
+err:
+	rcar_gyroadc_deinit_supplies(indio_dev);
+	return ret;
+}
+
+static int rcar_gyroadc_probe(struct platform_device *pdev)
+{
+	const struct of_device_id *of_id =
+		of_match_device(rcar_gyroadc_match, &pdev->dev);
+	struct device *dev = &pdev->dev;
+	struct rcar_gyroadc *priv;
+	struct iio_dev *indio_dev;
+	struct resource *mem;
+	int ret;
+
+	indio_dev = devm_iio_device_alloc(dev, sizeof(*priv));
+	if (!indio_dev) {
+		dev_err(dev, "Failed to allocate IIO device.\n");
+		return -ENOMEM;
+	}
+
+	priv = iio_priv(indio_dev);
+	priv->dev = dev;
+
+	mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	priv->regs = devm_ioremap_resource(dev, mem);
+	if (IS_ERR(priv->regs))
+		return PTR_ERR(priv->regs);
+
+	priv->iclk = devm_clk_get(dev, "if");
+	if (IS_ERR(priv->iclk)) {
+		ret = PTR_ERR(priv->iclk);
+		if (ret != -EPROBE_DEFER)
+			dev_err(dev, "Failed to get IF clock (ret=%i)\n", ret);
+		return ret;
+	}
+
+	ret = rcar_gyroadc_parse_subdevs(indio_dev);
+	if (ret)
+		return ret;
+
+	ret = rcar_gyroadc_init_supplies(indio_dev);
+	if (ret)
+		return ret;
+
+	priv->model = (enum rcar_gyroadc_model)of_id->data;
+
+	platform_set_drvdata(pdev, indio_dev);
+
+	indio_dev->name = dev_name(dev);
+	indio_dev->dev.parent = dev;
+	indio_dev->dev.of_node = pdev->dev.of_node;
+	indio_dev->info = &rcar_gyroadc_iio_info;
+	indio_dev->modes = INDIO_DIRECT_MODE;
+
+	pm_runtime_enable(dev);
+	pm_runtime_get_sync(dev);
+
+	ret = clk_prepare_enable(priv->iclk);

drivers/iio/adc/rcar-gyroadc.c line 481

Quoted 6 lines

drivers/iio/adc/rcar-gyroadc.c new file +6 -0

+	if (ret) {
+		dev_err(dev, "Could not prepare or enable the IF clock.\n");
+		goto error_clk_if_enable;
+	}
+
+	rcar_gyroadc_hw_init(priv);

This doesn't seem to be unwound on a failure in iio_device_register in particular the sampling isn't stopped on an error occuring.

Quoted 21 lines

drivers/iio/adc/rcar-gyroadc.c new file +21 -0

+
+	ret = iio_device_register(indio_dev);
+	if (ret) {
+		dev_err(dev, "Couldn't register IIO device.\n");
+		goto error_iio_device_register;
+	}
+
+	return 0;
+
+error_iio_device_register:
+	clk_disable_unprepare(priv->iclk);
+error_clk_if_enable:
+	pm_runtime_put(dev);
+	pm_runtime_disable(dev);
+	rcar_gyroadc_deinit_supplies(indio_dev);
+	return ret;
+}
+
+static int rcar_gyroadc_remove(struct platform_device *pdev)
+{
+	struct iio_dev *indio_dev = platform_get_drvdata(pdev);

drivers/iio/adc/rcar-gyroadc.c line 506

Quoted 4 lines

drivers/iio/adc/rcar-gyroadc.c new file +4 -0

+	struct rcar_gyroadc *priv = iio_priv(indio_dev);
+	struct device *dev = priv->dev;
+
+	/* Stop sampling */

I'd slightly prefer to see this wrapped up in a function that makes it clear it is unwinding the _init() call made in probe.
Also the ordering of remove should be the reverse of probe which I think means this should be somewhat later.

Quoted 19 lines

drivers/iio/adc/rcar-gyroadc.c new file +18 -0

+	writel(0, priv->regs + RCAR_GYROADC_START_STOP);
 
+
+	iio_device_unregister(indio_dev);
+	clk_disable_unprepare(priv->iclk);
+	pm_runtime_put(dev);
+	pm_runtime_disable(dev);
+	rcar_gyroadc_deinit_supplies(indio_dev);
+
+	return 0;
+}
+
+static struct platform_driver rcar_gyroadc_driver = {
+	.probe          = rcar_gyroadc_probe,
+	.remove         = rcar_gyroadc_remove,
+	.driver         = {
+		.name		= "rcar-gyroadc",
+		.of_match_table	= rcar_gyroadc_match,
+	},

drivers/iio/adc/rcar-gyroadc.c line 531

Quoted 8 lines

drivers/iio/adc/rcar-gyroadc.c new file +7 -0

+};
+
+module_platform_driver(rcar_gyroadc_driver);
+
+MODULE_AUTHOR("Marek Vasut <[email protected]>");
+MODULE_DESCRIPTION("Renesas R-Car GyroADC driver");
+MODULE_LICENSE("GPL");

Quoted 11 lines · Jonathan Cameron

Quoted 7 lines · Marek Vasut

Add IIO driver for the Renesas RCar GyroADC block. This block is a simple 4/8-channel ADC which samples 12/15/24 bits of data every cycle from all channels.

Signed-off-by Marek Vasut <[email protected]>

Cc Geert Uytterhoeven <[email protected]>

Cc Simon Horman <[email protected]>

Various minor bits and pieces. In particular I'm not keen on carrying on probing once we have a device tree entry that is 'wrong'. I'd bail there and then. This should never happen an is a bug.

OK, let's nuke that.

Quoted 4 lines

The only obvious exception would be if the device name wasn't supported 'yet'. Things to do with how it is described should result in hard errors.

Anyhow, basically looks pretty good.

Cool :-)

Quoted 74 lines

Jonathan

Quoted 73 lines

---
V2: - Spelling fixes
- Rename the driver source file to rcar-gyroadc
- Rework the channel sample width handling
- Use iio_device_claim_mode_direct()
- Rename "renesas,rcar-gyroadc" to "renesas,r8a7791-gyroadc" and rename "renesas,rcar-gyroadc-r8a7792" to "renesas,r8a7792-gyroadc" to match the new naming scheme (WARNING: scif uses the old one!)
- Switch to using regulators for channel voltage reference, add new properties renesas,gyroadc-vref-chN-supply for N in 0..7
- Handle vref regulators as optional to, make channels without vref regulator return EINVAL on read.
- Fix module license to GPL
- Drop interrupt.h include
- Rename clk to iclk
- Rename RCar to R-Car
- Rework the invalid mode handling
- Don't print error message on EPROBE_DEFER
- Drop fclk handling, use runtime PM for that instead
V3: - More R-Car spelling fixes
- Flip checks for V2H, since that's the only one that has interrupt registers
- Replace if-else statement with switch statement in init_mode
- Use unsigned types where applicable
- Rework timing calculation slightly to drop if-else block
- Use DIV_ROUND_CLOSEST
V4: - Add renesas,rcar-gyroadc fallback compatible string into the bindings
- Rework the ADC bindings to use per-channel subdevs
- Support more compatible ADC chips

---
 .../bindings/iio/adc/renesas,gyroadc.txt           |  70 +++
 MAINTAINERS                                        |   6 +
 drivers/iio/adc/Kconfig                            |  10 +
 drivers/iio/adc/Makefile                           |   1 +
 drivers/iio/adc/rcar-gyroadc.c                     | 531 +++++++++++++++++++++
 5 files changed, 618 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/iio/adc/renesas,gyroadc.txt
 create mode 100644 drivers/iio/adc/rcar-gyroadc.c

Documentation/devicetree/bindings/iio/adc/renesas,gyroadc.txt new file +28 -0

new file mode 100644
index 000000000000..2dcea9c8895b
@@ -0,0 +1,70 @@
+* Renesas RCar GyroADC device driver
+
+Required properties:
+- compatible:	Should be "renesas,<chip>-gyroadc", "renesas,rcar-gyroadc".
+		Use "renesas,r8a7792-gyroadc" for a GyroADC with interrupt
+		block found in R8A7792.
+- reg:		Address and length of the register set for the device
+- clocks:	References to all the clocks specified in the clock-names
+		property as specified in
+		Documentation/devicetree/bindings/clock/clock-bindings.txt.
+- clock-names:	Shall contain "fck" and "if". The "fck" is the GyroADC block
+		clock, the "if" is the interface clock.
+- power-domains: Must contain a reference to the PM domain, if available.
+- #address-cells: Should be <1> (setting for the subnodes)
+- #size-cells:	Should be <0> (setting for the subnodes)
+
+Sub-nodes:
+Optionally you can define subnodes which define the reference voltage
+for the analog inputs.
+
+Required properties for subnodes:
+- compatible:	Should be either of:
+		"fujitsu,mb88101a"
+			- Fujitsu MB88101A compatible mode,
+			  12bit sampling, 4 channels
+		"ti,adcs7476" or "ti,adc121" or "adi,ad7476"
+			- TI ADCS7476 / TI ADC121 / ADI AD7476 compatible mode,
+			  15bit sampling, 8 channels

Quoted 8 lines

Documentation/devicetree/bindings/iio/adc/renesas,gyroadc.txt line 31

Quoted 3 lines

Documentation/devicetree/bindings/iio/adc/renesas,gyroadc.txt new file +3 -0

+		"maxim,max1162" or "maxim,max11100"
+			- Maxim MAX1162 / Maxim MAX11100 compatible mode,
+			  16bit sampling, 8 channels

Worth putting something here about how this might be interfaced. Realistically we are either looking at some extra circuitry or supporting only 3 of the channels.
The max11100 is only a single channel device for example. This description doesn't make it clear that 8 of them would be needed to do 8 channels.

All right, what about this:

- compatible:Should be either of:
"fujitsu,mb88101a"
- Fujitsu MB88101A compatible mode,
12bit sampling, up to 4 channels can be sampled in round-robin fashion. One Fujitsu chip supplies four GyroADC channels with data as it contains four ADCs on the chip and thus for 4-channel operation, single MB88101A is required. The Cx chipselect lines of the MB88101A connect directly to two CHS lines of the GyroADC, no demuxer is required. The data out line of each MB88101A connects to a shared input pin of the GyroADC.
"ti,adcs7476" or "ti,adc121" or "adi,ad7476"
- TI ADCS7476 / TI ADC121 / ADI AD7476 compatible mode, 15bit sampling, up to 8 channels can be sampled in round-robin fashion. One TI/ADI chip supplies single ADC channel with data, thus for 8-channel operation, 8 chips are required. A 3:8 chipselect demuxer is required to connect the nCS line of the TI/ADI chips to the GyroADC, while MISO line of each TI/ADI ADC connects to a shared input pin of the GyroADC.
"maxim,max1162" or "maxim,max11100"

- Maxim MAX1162 / Maxim MAX11100 compatible mode, 16bit sampling, up to 8 channels can be sampled in round-robin fashion. One Maxim chip supplies single ADC channel with data, thus for 8-channel operation, 8 chips are required. A 3:8 chipselect demuxer is required to connect the nCS line of the MAX chips to the GyroADC, while MISO line of each Maxim ADC connects to a shared input pin of the GyroADC.

Quoted 65 lines

Quoted 65 lines

Documentation/devicetree/bindings/iio/adc/renesas,gyroadc.txt new file +39 -0

+- reg:		Should be the number of the analog input.
+- vref-supply:	Reference to the channel reference voltage regulator.
+
+Example:
+	vref_max1162: regulator-vref-max1162 {
+		compatible = "regulator-fixed";
+
+		regulator-name = "MAX1162 Vref";
+		regulator-min-microvolt = <4096000>;
+		regulator-max-microvolt = <4096000>;
+	};
+
+	&adc {
+		compatible = "renesas,r8a7791-gyroadc", "renesas,rcar-gyroadc";
+		reg = <0 0xe6e54000 0 64>;
+		clocks = <&mstp9_clks R8A7791_CLK_GYROADC>, <&clk_65m>;
+		clock-names = "fck", "if";
+		power-domains = <&sysc R8A7791_PD_ALWAYS_ON>;
+
+		pinctrl-0 = <&adc_pins>;
+		pinctrl-names = "default";
+
+		status = "okay";
+
+		#address-cells = <1>;
+		#size-cells = <0>;
+
+		adc@0 {
+			reg = <0>;
+			compatible = "maxim,max1162";
+			vref-supply = <&vref_max1162>;
+		};
+
+		adc@1 {
+			reg = <1>;
+			compatible = "maxim,max1162";
+			vref-supply = <&vref_max1162>;
+		};
+	};

MAINTAINERS +6 -0

index 890fc9e3c191..498e8a755eb6 100644
@@ -10276,6 +10276,12 @@ L:	[email protected]
 F:	drivers/net/ethernet/renesas/
 F:	include/linux/sh_eth.h
 
+RENESAS R-CAR GYROADC DRIVER
+M:	Marek Vasut <[email protected]>
+L:	[email protected]
+S:	Supported
+F:	drivers/iio/adc/rcar_gyro_adc.c
+
 RENESAS USB2 PHY DRIVER
 M:	Yoshihiro Shimoda <[email protected]>
 L:	[email protected]

drivers/iio/adc/Kconfig +0 -0

index 99c051490eff..f9954c71048d 100644
@@ -408,6 +408,16 @@ config QCOM_SPMI_VADC
 	  To compile this driver as a module, choose M here: the module will
 	  be called qcom-spmi-vadc.
 

Quoted 8 lines

drivers/iio/adc/Kconfig config QCOM_SPMI_VADC · line 416

Quoted 6 lines

drivers/iio/adc/Kconfig +6 -0

+config RCAR_GYRO_ADC
+	tristate "Renesas R-Car GyroADC driver"
+	depends on ARCH_RCAR_GEN2 || (ARM && COMPILE_TEST)
+	help
+	  Say yes here to build support for the GyroADC found in Renesas
+	  R-Car Gen2 SoCs.

Put a bit more detail here perhaps - it's not really an ADC afterall but a rather dumb spi offload engine.

I am so borrowing this one :)

If it was slightly smarter I'd suggest

Quoted 2 lines

supporting it through that infrastructure. That would require changes in every relevant driver though so not terribly elegant.

Yeah, I had that discussion with Lars and Mark Brown already :)

Quoted 122 lines

Quoted 122 lines

drivers/iio/adc/Kconfig +4 -0

+
+	  To compile this driver as a module, choose M here: the
+	  module will be called rcar-gyroadc.
+
 config ROCKCHIP_SARADC
 	tristate "Rockchip SARADC driver"
 	depends on ARCH_ROCKCHIP || (ARM && COMPILE_TEST)

drivers/iio/adc/Makefile +1 -0

index 7a40c04c311f..13db7c2bffc8 100644
@@ -39,6 +39,7 @@ obj-$(CONFIG_NAU7802) += nau7802.o
 obj-$(CONFIG_PALMAS_GPADC) += palmas_gpadc.o
 obj-$(CONFIG_QCOM_SPMI_IADC) += qcom-spmi-iadc.o
 obj-$(CONFIG_QCOM_SPMI_VADC) += qcom-spmi-vadc.o
+obj-$(CONFIG_RCAR_GYRO_ADC) += rcar-gyroadc.o
 obj-$(CONFIG_ROCKCHIP_SARADC) += rockchip_saradc.o
 obj-$(CONFIG_STX104) += stx104.o
 obj-$(CONFIG_TI_ADC081C) += ti-adc081c.o

drivers/iio/adc/rcar-gyroadc.c new file +97 -0

new file mode 100644
index 000000000000..14f139613e1c
@@ -0,0 +1,531 @@
+/*
+ * Renesas R-Car GyroADC driver
+ *
+ * Copyright 2016 Marek Vasut <[email protected]>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/delay.h>
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/io.h>
+#include <linux/clk.h>
+#include <linux/of.h>
+#include <linux/of_irq.h>
+#include <linux/regulator/consumer.h>
+#include <linux/of_platform.h>
+#include <linux/err.h>
+#include <linux/pm_runtime.h>
+
+#include <linux/iio/iio.h>
+#include <linux/iio/buffer.h>
+#include <linux/iio/sysfs.h>
+#include <linux/iio/trigger.h>
+
+/* GyroADC registers. */
+#define RCAR_GYROADC_MODE_SELECT		0x00
+#define RCAR_GYROADC_MODE_SELECT_1_MB88101A	0x0
+#define RCAR_GYROADC_MODE_SELECT_2_ADCS7476	0x1
+#define RCAR_GYROADC_MODE_SELECT_3_MAX1162	0x3
+
+#define RCAR_GYROADC_START_STOP			0x04
+#define RCAR_GYROADC_START_STOP_START		BIT(0)
+
+#define RCAR_GYROADC_CLOCK_LENGTH		0x08
+#define RCAR_GYROADC_1_25MS_LENGTH		0x0c
+
+#define RCAR_GYROADC_REALTIME_DATA(ch)		(0x10 + ((ch) * 4))
+#define RCAR_GYROADC_100MS_ADDED_DATA(ch)	(0x30 + ((ch) * 4))
+#define RCAR_GYROADC_10MS_AVG_DATA(ch)		(0x50 + ((ch) * 4))
+
+#define RCAR_GYROADC_FIFO_STATUS		0x70
+#define RCAR_GYROADC_FIFO_STATUS_EMPTY(ch)	BIT(0 + (4 * (ch)))
+#define RCAR_GYROADC_FIFO_STATUS_FULL(ch)	BIT(1 + (4 * (ch)))
+#define RCAR_GYROADC_FIFO_STATUS_ERROR(ch)	BIT(2 + (4 * (ch)))
+
+#define RCAR_GYROADC_INTR			0x74
+#define RCAR_GYROADC_INTR_INT			BIT(0)
+
+#define RCAR_GYROADC_INTENR			0x78
+#define RCAR_GYROADC_INTENR_INTEN		BIT(0)
+
+#define RCAR_GYROADC_SAMPLE_RATE		800	/* Hz */
+
+enum rcar_gyroadc_model {
+	RCAR_GYROADC_MODEL_DEFAULT,
+	RCAR_GYROADC_MODEL_R8A7792,
+};
+
+struct rcar_gyroadc {
+	struct device			*dev;
+	void __iomem			*regs;
+	struct clk			*iclk;
+	struct regulator		*vref[8];
+	unsigned int			num_channels;
+	enum rcar_gyroadc_model		model;
+	unsigned int			mode;
+	unsigned int			sample_width;
+	u32				buffer[8];
+};
+
+static void rcar_gyroadc_hw_init(struct rcar_gyroadc *priv)
+{
+	const unsigned long clk_mhz = clk_get_rate(priv->iclk) / 1000000;
+	const unsigned long clk_mul =
+		(priv->mode == RCAR_GYROADC_MODE_SELECT_1_MB88101A) ? 10 : 5;
+
+	/* Stop the GyroADC. */
+	writel(0, priv->regs + RCAR_GYROADC_START_STOP);
+
+	/* Disable IRQ on V2H. */
+	if (priv->model == RCAR_GYROADC_MODEL_R8A7792)
+		writel(0, priv->regs + RCAR_GYROADC_INTENR);
+
+	/* Set mode and timing. */
+	writel(priv->mode, priv->regs + RCAR_GYROADC_MODE_SELECT);
+	writel(clk_mhz * clk_mul, priv->regs + RCAR_GYROADC_CLOCK_LENGTH);

Quoted 8 lines

drivers/iio/adc/rcar-gyroadc.c line 103

Quoted 6 lines

drivers/iio/adc/rcar-gyroadc.c new file +6 -0

+	writel(clk_mhz * 1250, priv->regs + RCAR_GYROADC_1_25MS_LENGTH);
+
+	/*
+	 * We can possibly turn the sampling on/off on-demand to reduce power
+	 * consumption, but for the sake of quick availability of samples, we
+	 * don't do it now.

Typically, if you want to do this, do it with runtime_pm and use the auto suspend stuff. Can work well.

You mean keep sampling and let the runtime PM just turn the clock to this block on/off ?

Quoted 33 lines

Quoted 33 lines

drivers/iio/adc/rcar-gyroadc.c new file +32 -0

+	 */
+	writel(RCAR_GYROADC_START_STOP_START,
+	       priv->regs + RCAR_GYROADC_START_STOP);
+
+	/* Wait for the first conversion to complete. */
+	udelay(1250);
+}
+
+#define RCAR_GYROADC_CHAN(_idx) {				\
+	.type			= IIO_VOLTAGE,			\
+	.indexed		= 1,				\
+	.channel		= (_idx),			\
+	.info_mask_separate	= BIT(IIO_CHAN_INFO_RAW) |	\
+				  BIT(IIO_CHAN_INFO_SCALE),	\
+	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SAMP_FREQ), \
+}
+
+static const struct iio_chan_spec rcar_gyroadc_iio_channels_1[] = {
+	RCAR_GYROADC_CHAN(0),
+	RCAR_GYROADC_CHAN(1),
+	RCAR_GYROADC_CHAN(2),
+	RCAR_GYROADC_CHAN(3),
+};
+
+static const struct iio_chan_spec rcar_gyroadc_iio_channels_2[] = {
+	RCAR_GYROADC_CHAN(0),
+	RCAR_GYROADC_CHAN(1),
+	RCAR_GYROADC_CHAN(2),
+	RCAR_GYROADC_CHAN(3),
+	RCAR_GYROADC_CHAN(4),
+	RCAR_GYROADC_CHAN(5),
+	RCAR_GYROADC_CHAN(6),

Quoted 8 lines

drivers/iio/adc/rcar-gyroadc.c line 141

Quoted 6 lines

drivers/iio/adc/rcar-gyroadc.c new file +6 -0

+	RCAR_GYROADC_CHAN(7),
+};
+
+/*
+ * NOTE: The data we receive in mode 3 from MAX1162 have MSByte = 0,
+ *       therefore we only use 16bit realbits here instead of 24.

Umm. That would be a fair comment if realbits was set at all! With what you are currently supporting it shouldn't be.

Dropped, thanks.

Quoted 43 lines

Quoted 43 lines

drivers/iio/adc/rcar-gyroadc.c new file +43 -0

+ */
+static const struct iio_chan_spec rcar_gyroadc_iio_channels_3[] = {
+	RCAR_GYROADC_CHAN(0),
+	RCAR_GYROADC_CHAN(1),
+	RCAR_GYROADC_CHAN(2),
+	RCAR_GYROADC_CHAN(3),
+	RCAR_GYROADC_CHAN(4),
+	RCAR_GYROADC_CHAN(5),
+	RCAR_GYROADC_CHAN(6),
+	RCAR_GYROADC_CHAN(7),
+};
+
+static int rcar_gyroadc_read_raw(struct iio_dev *indio_dev,
+				 struct iio_chan_spec const *chan,
+				 int *val, int *val2, long mask)
+{
+	struct rcar_gyroadc *priv = iio_priv(indio_dev);
+	struct regulator *consumer = priv->vref[chan->channel];
+	unsigned int datareg = RCAR_GYROADC_REALTIME_DATA(chan->channel);
+	unsigned int vref;
+	int ret;
+
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW:
+		if (chan->type != IIO_VOLTAGE)
+			return -EINVAL;
+
+		/* Channel not connected. */
+		if (!consumer)
+			return -EINVAL;
+
+		ret = iio_device_claim_direct_mode(indio_dev);
+		if (ret)
+			return ret;
+
+		*val = readl(priv->regs + datareg);
+		*val &= BIT(priv->sample_width) - 1;
+
+		iio_device_release_direct_mode(indio_dev);
+
+		return IIO_VAL_INT;
+	case IIO_CHAN_INFO_SCALE:
+		/* Channel not connected. */

Quoted 8 lines

drivers/iio/adc/rcar-gyroadc.c line 190

Quoted 6 lines

drivers/iio/adc/rcar-gyroadc.c new file +6 -0

+		if (!consumer)
+			return -EINVAL;
+
+		vref = regulator_get_voltage(consumer);
+		*val = 0;
+		*val2 = DIV_ROUND_CLOSEST(vref * 1000, 0x10000);

spacing is a bit variable. Sometimes you leave a line before the return, sometimes you don't. Pick one or the other and it'll read slightly better!

A newline before return it is, it makes things a bit more readable IMO.

Quoted 155 lines

Quoted 94 lines

drivers/iio/adc/rcar-gyroadc.c new file +94 -0

+		return IIO_VAL_INT_PLUS_NANO;
+	case IIO_CHAN_INFO_SAMP_FREQ:
+		*val = RCAR_GYROADC_SAMPLE_RATE;
+		return IIO_VAL_INT;
+	default:
+		return -EINVAL;
+	}
+}
+
+static int rcar_gyroadc_reg_access(struct iio_dev *indio_dev,
+				   unsigned int reg, unsigned int writeval,
+				   unsigned int *readval)
+{
+	struct rcar_gyroadc *priv = iio_priv(indio_dev);
+	unsigned int maxreg = RCAR_GYROADC_FIFO_STATUS;
+
+	if (readval == NULL)
+		return -EINVAL;
+
+	if (reg % 4)
+		return -EINVAL;
+
+	/* Handle the V2H case with extra interrupt block. */
+	if (priv->model == RCAR_GYROADC_MODEL_R8A7792)
+		maxreg = RCAR_GYROADC_INTENR;
+
+	if (reg > maxreg)
+		return -EINVAL;
+
+	*readval = readl(priv->regs + reg);
+
+	return 0;
+}
+
+static const struct iio_info rcar_gyroadc_iio_info = {
+	.driver_module		= THIS_MODULE,
+	.read_raw		= rcar_gyroadc_read_raw,
+	.debugfs_reg_access	= rcar_gyroadc_reg_access,
+};
+
+static const struct of_device_id rcar_gyroadc_match[] = {
+	{
+		/* R-Car compatible GyroADC */
+		.compatible	= "renesas,rcar-gyroadc",
+		.data		= (void *)RCAR_GYROADC_MODEL_DEFAULT,
+	}, {
+		/* R-Car V2H specialty with interrupt registers. */
+		.compatible	= "renesas,r8a7792-gyroadc",
+		.data		= (void *)RCAR_GYROADC_MODEL_R8A7792,
+	}, {
+		/* sentinel */
+	}
+};
+
+MODULE_DEVICE_TABLE(of, rcar_gyroadc_match);
+
+static const struct of_device_id rcar_gyroadc_child_match[] = {
+	/* Mode 1 ADCs */
+	{
+		.compatible	= "fujitsu,mb88101a",
+		.data		= (void *)RCAR_GYROADC_MODE_SELECT_1_MB88101A,
+	},
+	/* Mode 2 ADCs */
+	{
+		.compatible	= "ti,adcs7476",
+		.data		= (void *)RCAR_GYROADC_MODE_SELECT_2_ADCS7476,
+	}, {
+		.compatible	= "ti,adc121",
+		.data		= (void *)RCAR_GYROADC_MODE_SELECT_2_ADCS7476,
+	}, {
+		.compatible	= "adi,ad7476",
+		.data		= (void *)RCAR_GYROADC_MODE_SELECT_2_ADCS7476,
+	},
+	/* Mode 3 ADCs */
+	{
+		.compatible	= "maxim,max1162",
+		.data		= (void *)RCAR_GYROADC_MODE_SELECT_3_MAX1162,
+	}, {
+		.compatible	= "maxim,max11100",
+		.data		= (void *)RCAR_GYROADC_MODE_SELECT_3_MAX1162,
+	},
+	{ /* sentinel */ }
+};
+
+static int rcar_gyroadc_parse_subdevs(struct iio_dev *indio_dev)
+{
+	const struct of_device_id *of_id;
+	const struct iio_chan_spec *channels;
+	struct rcar_gyroadc *priv = iio_priv(indio_dev);
+	struct device *dev = priv->dev;
+	struct device_node *np = dev->of_node;
+	struct device_node *child;
+	struct regulator *vref;
+	unsigned int reg, maxreg;

drivers/iio/adc/rcar-gyroadc.c line 294

Quoted 10 lines

drivers/iio/adc/rcar-gyroadc.c new file +10 -0

+	unsigned int adcmode, childmode;
+	unsigned int sample_width;
+	unsigned int num_channels;
+	int ret, first = 1;
+
+	for_each_child_of_node(np, child) {
+		of_id = of_match_node(rcar_gyroadc_child_match, child);
+		if (!of_id) {
+			dev_err(dev, "Ignoring unsupported ADC \"%s\".",
+				child->name);

This is the only case that should result in a continue.

Quoted 37 lines

drivers/iio/adc/rcar-gyroadc.c new file +37 -0

+			continue;
+		}
+
+		ret = of_property_read_u32(child, "reg", &reg);
+		if (ret) {
+			dev_err(dev,
+				"Failed to get child reg property of ADC \"%s\".\n",
+				child->name);
+			continue;
+		}
+
+		childmode = (unsigned int)of_id->data;
+		switch (childmode) {
+		case RCAR_GYROADC_MODE_SELECT_1_MB88101A:
+			maxreg = 4;
+			sample_width = 12;
+			channels = rcar_gyroadc_iio_channels_1;
+			num_channels = ARRAY_SIZE(rcar_gyroadc_iio_channels_1);
+			break;
+		case RCAR_GYROADC_MODE_SELECT_2_ADCS7476:
+			maxreg = 8;
+			sample_width = 15;
+			channels = rcar_gyroadc_iio_channels_2;
+			num_channels = ARRAY_SIZE(rcar_gyroadc_iio_channels_2);
+			break;
+		case RCAR_GYROADC_MODE_SELECT_3_MAX1162:
+			maxreg = 8;
+			sample_width = 16;
+			channels = rcar_gyroadc_iio_channels_3;
+			num_channels = ARRAY_SIZE(rcar_gyroadc_iio_channels_3);
+			break;
+		}
+
+		/* Channel number is too high. */
+		if (reg >= maxreg) {
+			dev_err(dev,
+				"Only %i channels supported with %s, but reg = <%i>, ignoring.\n",

drivers/iio/adc/rcar-gyroadc.c line 341

Quoted 10 lines

drivers/iio/adc/rcar-gyroadc.c new file +10 -0

+				maxreg, child->name, reg);
+			continue;
+		}
+
+		/* Child node selected different mode than the rest. */
+		if (!first && (adcmode != childmode)) {
+			dev_err(dev,
+				"Channel %i uses different ADC mode than the rest, ignoring.\n",
+				reg);
+			continue;

Fail hard - not softly - I'd expect the probe to completely fail if the device tree is invalid in this way.

Quoted 1 line

Same is true for other conditions above. Don't paper over the issue please.

OK

Quoted 7 lines

Quoted 7 lines

drivers/iio/adc/rcar-gyroadc.c new file +7 -0

+		}
+
+		/* Channel is valid, grab the regulator. */
+		dev->of_node = child;
+		vref = devm_regulator_get_optional(dev, "vref");
+		dev->of_node = np;
+		if (IS_ERR(vref)) {

Quoted 8 lines

drivers/iio/adc/rcar-gyroadc.c line 354

Quoted 6 lines

drivers/iio/adc/rcar-gyroadc.c new file +6 -0

+			/*
+			 * Regulator is not present, which means the channel
+			 * supply is not connected.
+			 */
+			dev_dbg(dev, "Channel %i 'vref' supply not connected\n",
+				reg);

Error out rather than carrying on to try other channels. If the device tree is invalid we want to know and fail hard.

OK

Quoted 121 lines

Quoted 121 lines

drivers/iio/adc/rcar-gyroadc.c new file +121 -0

+			continue;
+		}
+
+		priv->vref[reg] = vref;
+
+		if (!first)
+			continue;
+
+		/* First child node which passed sanity tests. */
+		adcmode = childmode;
+		first = 0;
+
+		priv->num_channels = maxreg;
+		priv->mode = childmode;
+		priv->sample_width = sample_width;
+
+		indio_dev->channels = channels;
+		indio_dev->num_channels = num_channels;
+	}
+
+	if (first) {
+		dev_err(dev, "No valid ADC channels found, aborting.\n");
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static void rcar_gyroadc_deinit_supplies(struct iio_dev *indio_dev)
+{
+	struct rcar_gyroadc *priv = iio_priv(indio_dev);
+	unsigned int i;
+
+	for (i = 0; i < priv->num_channels; i++) {
+		if (!priv->vref[i])
+			continue;
+
+		regulator_disable(priv->vref[i]);
+	}
+}
+
+static int rcar_gyroadc_init_supplies(struct iio_dev *indio_dev)
+{
+	struct rcar_gyroadc *priv = iio_priv(indio_dev);
+	struct device *dev = priv->dev;
+	unsigned int i;
+	int ret;
+
+	for (i = 0; i < priv->num_channels; i++) {
+		if (!priv->vref[i])
+			continue;
+
+		ret = regulator_enable(priv->vref[i]);
+		if (ret) {
+			dev_err(dev, "Failed to enable regulator %i (ret=%i)\n",
+				i, ret);
+			goto err;
+		}
+	}
+
+	return 0;
+
+err:
+	rcar_gyroadc_deinit_supplies(indio_dev);
+	return ret;
+}
+
+static int rcar_gyroadc_probe(struct platform_device *pdev)
+{
+	const struct of_device_id *of_id =
+		of_match_device(rcar_gyroadc_match, &pdev->dev);
+	struct device *dev = &pdev->dev;
+	struct rcar_gyroadc *priv;
+	struct iio_dev *indio_dev;
+	struct resource *mem;
+	int ret;
+
+	indio_dev = devm_iio_device_alloc(dev, sizeof(*priv));
+	if (!indio_dev) {
+		dev_err(dev, "Failed to allocate IIO device.\n");
+		return -ENOMEM;
+	}
+
+	priv = iio_priv(indio_dev);
+	priv->dev = dev;
+
+	mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	priv->regs = devm_ioremap_resource(dev, mem);
+	if (IS_ERR(priv->regs))
+		return PTR_ERR(priv->regs);
+
+	priv->iclk = devm_clk_get(dev, "if");
+	if (IS_ERR(priv->iclk)) {
+		ret = PTR_ERR(priv->iclk);
+		if (ret != -EPROBE_DEFER)
+			dev_err(dev, "Failed to get IF clock (ret=%i)\n", ret);
+		return ret;
+	}
+
+	ret = rcar_gyroadc_parse_subdevs(indio_dev);
+	if (ret)
+		return ret;
+
+	ret = rcar_gyroadc_init_supplies(indio_dev);
+	if (ret)
+		return ret;
+
+	priv->model = (enum rcar_gyroadc_model)of_id->data;
+
+	platform_set_drvdata(pdev, indio_dev);
+
+	indio_dev->name = dev_name(dev);
+	indio_dev->dev.parent = dev;
+	indio_dev->dev.of_node = pdev->dev.of_node;
+	indio_dev->info = &rcar_gyroadc_iio_info;
+	indio_dev->modes = INDIO_DIRECT_MODE;
+
+	pm_runtime_enable(dev);
+	pm_runtime_get_sync(dev);
+
+	ret = clk_prepare_enable(priv->iclk);

Quoted 8 lines

drivers/iio/adc/rcar-gyroadc.c line 481

Quoted 6 lines

drivers/iio/adc/rcar-gyroadc.c new file +6 -0

+	if (ret) {
+		dev_err(dev, "Could not prepare or enable the IF clock.\n");
+		goto error_clk_if_enable;
+	}
+
+	rcar_gyroadc_hw_init(priv);

This doesn't seem to be unwound on a failure in iio_device_register in particular the sampling isn't stopped on an error occuring.

Ah, nice catch and fixed.

Quoted 21 lines

Quoted 21 lines

drivers/iio/adc/rcar-gyroadc.c new file +21 -0

+
+	ret = iio_device_register(indio_dev);
+	if (ret) {
+		dev_err(dev, "Couldn't register IIO device.\n");
+		goto error_iio_device_register;
+	}
+
+	return 0;
+
+error_iio_device_register:
+	clk_disable_unprepare(priv->iclk);
+error_clk_if_enable:
+	pm_runtime_put(dev);
+	pm_runtime_disable(dev);
+	rcar_gyroadc_deinit_supplies(indio_dev);
+	return ret;
+}
+
+static int rcar_gyroadc_remove(struct platform_device *pdev)
+{
+	struct iio_dev *indio_dev = platform_get_drvdata(pdev);

Quoted 8 lines

drivers/iio/adc/rcar-gyroadc.c line 506

Quoted 4 lines

drivers/iio/adc/rcar-gyroadc.c new file +4 -0

+	struct rcar_gyroadc *priv = iio_priv(indio_dev);
+	struct device *dev = priv->dev;
+
+	/* Stop sampling */

I'd slightly prefer to see this wrapped up in a function that makes it clear it is unwinding the _init() call made in probe.
Also the ordering of remove should be the reverse of probe which I think means this should be somewhat later.

Yup and both fixed.

Quoted 19 lines

Quoted 19 lines

drivers/iio/adc/rcar-gyroadc.c new file +18 -0

+	writel(0, priv->regs + RCAR_GYROADC_START_STOP);
 
+
+	iio_device_unregister(indio_dev);
+	clk_disable_unprepare(priv->iclk);
+	pm_runtime_put(dev);
+	pm_runtime_disable(dev);
+	rcar_gyroadc_deinit_supplies(indio_dev);
+
+	return 0;
+}
+
+static struct platform_driver rcar_gyroadc_driver = {
+	.probe          = rcar_gyroadc_probe,
+	.remove         = rcar_gyroadc_remove,
+	.driver         = {
+		.name		= "rcar-gyroadc",
+		.of_match_table	= rcar_gyroadc_match,
+	},

Quoted 8 lines

drivers/iio/adc/rcar-gyroadc.c line 531

Quoted 8 lines

drivers/iio/adc/rcar-gyroadc.c new file +7 -0

+};
+
+module_platform_driver(rcar_gyroadc_driver);
+
+MODULE_AUTHOR("Marek Vasut <[email protected]>");
+MODULE_DESCRIPTION("Renesas R-Car GyroADC driver");
+MODULE_LICENSE("GPL");

Thanks!

Quoted 129 lines · Marek Vasut

Quoted 11 lines · Jonathan Cameron

Quoted 7 lines · Marek Vasut

Add IIO driver for the Renesas RCar GyroADC block. This block is a simple 4/8-channel ADC which samples 12/15/24 bits of data every cycle from all channels.

Signed-off-by Marek Vasut <[email protected]>

Cc Geert Uytterhoeven <[email protected]>

Cc Simon Horman <[email protected]>

Various minor bits and pieces. In particular I'm not keen on carrying on probing once we have a device tree entry that is 'wrong'. I'd bail there and then. This should never happen an is a bug.

OK, let's nuke that.

Quoted 4 lines

The only obvious exception would be if the device name wasn't supported 'yet'. Things to do with how it is described should result in hard errors.

Anyhow, basically looks pretty good.

Cool :-)

Quoted 74 lines

Jonathan

Quoted 73 lines

---
V2: - Spelling fixes
- Rename the driver source file to rcar-gyroadc
- Rework the channel sample width handling
- Use iio_device_claim_mode_direct()
- Rename "renesas,rcar-gyroadc" to "renesas,r8a7791-gyroadc" and rename "renesas,rcar-gyroadc-r8a7792" to "renesas,r8a7792-gyroadc" to match the new naming scheme (WARNING: scif uses the old one!)
- Switch to using regulators for channel voltage reference, add new properties renesas,gyroadc-vref-chN-supply for N in 0..7
- Handle vref regulators as optional to, make channels without vref regulator return EINVAL on read.
- Fix module license to GPL
- Drop interrupt.h include
- Rename clk to iclk
- Rename RCar to R-Car
- Rework the invalid mode handling
- Don't print error message on EPROBE_DEFER
- Drop fclk handling, use runtime PM for that instead
V3: - More R-Car spelling fixes
- Flip checks for V2H, since that's the only one that has interrupt registers
- Replace if-else statement with switch statement in init_mode
- Use unsigned types where applicable
- Rework timing calculation slightly to drop if-else block
- Use DIV_ROUND_CLOSEST
V4: - Add renesas,rcar-gyroadc fallback compatible string into the bindings
- Rework the ADC bindings to use per-channel subdevs
- Support more compatible ADC chips

---
 .../bindings/iio/adc/renesas,gyroadc.txt           |  70 +++
 MAINTAINERS                                        |   6 +
 drivers/iio/adc/Kconfig                            |  10 +
 drivers/iio/adc/Makefile                           |   1 +
 drivers/iio/adc/rcar-gyroadc.c                     | 531 +++++++++++++++++++++
 5 files changed, 618 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/iio/adc/renesas,gyroadc.txt
 create mode 100644 drivers/iio/adc/rcar-gyroadc.c

Documentation/devicetree/bindings/iio/adc/renesas,gyroadc.txt new file +28 -0

new file mode 100644
index 000000000000..2dcea9c8895b
@@ -0,0 +1,70 @@
+* Renesas RCar GyroADC device driver
+
+Required properties:
+- compatible:	Should be "renesas,<chip>-gyroadc", "renesas,rcar-gyroadc".
+		Use "renesas,r8a7792-gyroadc" for a GyroADC with interrupt
+		block found in R8A7792.
+- reg:		Address and length of the register set for the device
+- clocks:	References to all the clocks specified in the clock-names
+		property as specified in
+		Documentation/devicetree/bindings/clock/clock-bindings.txt.
+- clock-names:	Shall contain "fck" and "if". The "fck" is the GyroADC block
+		clock, the "if" is the interface clock.
+- power-domains: Must contain a reference to the PM domain, if available.
+- #address-cells: Should be <1> (setting for the subnodes)
+- #size-cells:	Should be <0> (setting for the subnodes)
+
+Sub-nodes:
+Optionally you can define subnodes which define the reference voltage
+for the analog inputs.
+
+Required properties for subnodes:
+- compatible:	Should be either of:
+		"fujitsu,mb88101a"
+			- Fujitsu MB88101A compatible mode,
+			  12bit sampling, 4 channels
+		"ti,adcs7476" or "ti,adc121" or "adi,ad7476"
+			- TI ADCS7476 / TI ADC121 / ADI AD7476 compatible mode,
+			  15bit sampling, 8 channels

Quoted 8 lines

Documentation/devicetree/bindings/iio/adc/renesas,gyroadc.txt line 31

Quoted 3 lines

Documentation/devicetree/bindings/iio/adc/renesas,gyroadc.txt new file +3 -0

+		"maxim,max1162" or "maxim,max11100"
+			- Maxim MAX1162 / Maxim MAX11100 compatible mode,
+			  16bit sampling, 8 channels

Worth putting something here about how this might be interfaced. Realistically we are either looking at some extra circuitry or supporting only 3 of the channels.
The max11100 is only a single channel device for example. This description doesn't make it clear that 8 of them would be needed to do 8 channels.

All right, what about this:

- compatible:Should be either of:
"fujitsu,mb88101a"
- Fujitsu MB88101A compatible mode,
12bit sampling, up to 4 channels can be sampled in round-robin fashion. One Fujitsu chip supplies four GyroADC channels with data as it contains four ADCs on the chip and thus for 4-channel operation, single MB88101A is required. The Cx chipselect lines of the MB88101A connect directly to two CHS lines of the GyroADC, no demuxer is required. The data out line of each MB88101A connects to a shared input pin of the GyroADC.
"ti,adcs7476" or "ti,adc121" or "adi,ad7476"
- TI ADCS7476 / TI ADC121 / ADI AD7476 compatible mode, 15bit sampling, up to 8 channels can be sampled in round-robin fashion. One TI/ADI chip supplies single ADC channel with data, thus for 8-channel operation, 8 chips are required. A 3:8 chipselect demuxer is required to connect the nCS line of the TI/ADI chips to the GyroADC, while MISO line of each TI/ADI ADC connects to a shared input pin of the GyroADC.
"maxim,max1162" or "maxim,max11100"

Quoted 8 lines

- Maxim MAX1162 / Maxim MAX11100 compatible mode, 16bit sampling, up to 8 channels can be sampled in round-robin fashion. One Maxim chip supplies single ADC channel with data, thus for 8-channel operation, 8 chips are required. A 3:8 chipselect demuxer is required to connect the nCS line of the MAX chips to the GyroADC, while MISO line of each Maxim ADC connects to a shared input pin of the GyroADC.

Excellent.

Quoted 212 lines

Quoted 64 lines

Quoted 64 lines

Documentation/devicetree/bindings/iio/adc/renesas,gyroadc.txt new file +39 -0

+- reg:		Should be the number of the analog input.
+- vref-supply:	Reference to the channel reference voltage regulator.
+
+Example:
+	vref_max1162: regulator-vref-max1162 {
+		compatible = "regulator-fixed";
+
+		regulator-name = "MAX1162 Vref";
+		regulator-min-microvolt = <4096000>;
+		regulator-max-microvolt = <4096000>;
+	};
+
+	&adc {
+		compatible = "renesas,r8a7791-gyroadc", "renesas,rcar-gyroadc";
+		reg = <0 0xe6e54000 0 64>;
+		clocks = <&mstp9_clks R8A7791_CLK_GYROADC>, <&clk_65m>;
+		clock-names = "fck", "if";
+		power-domains = <&sysc R8A7791_PD_ALWAYS_ON>;
+
+		pinctrl-0 = <&adc_pins>;
+		pinctrl-names = "default";
+
+		status = "okay";
+
+		#address-cells = <1>;
+		#size-cells = <0>;
+
+		adc@0 {
+			reg = <0>;
+			compatible = "maxim,max1162";
+			vref-supply = <&vref_max1162>;
+		};
+
+		adc@1 {
+			reg = <1>;
+			compatible = "maxim,max1162";
+			vref-supply = <&vref_max1162>;
+		};
+	};

MAINTAINERS +6 -0

index 890fc9e3c191..498e8a755eb6 100644
@@ -10276,6 +10276,12 @@ L:	[email protected]
 F:	drivers/net/ethernet/renesas/
 F:	include/linux/sh_eth.h
 
+RENESAS R-CAR GYROADC DRIVER
+M:	Marek Vasut <[email protected]>
+L:	[email protected]
+S:	Supported
+F:	drivers/iio/adc/rcar_gyro_adc.c
+
 RENESAS USB2 PHY DRIVER
 M:	Yoshihiro Shimoda <[email protected]>
 L:	[email protected]

drivers/iio/adc/Kconfig +0 -0

index 99c051490eff..f9954c71048d 100644
@@ -408,6 +408,16 @@ config QCOM_SPMI_VADC
 	  To compile this driver as a module, choose M here: the module will
 	  be called qcom-spmi-vadc.
 

Quoted 8 lines

drivers/iio/adc/Kconfig config QCOM_SPMI_VADC · line 416

Quoted 6 lines

drivers/iio/adc/Kconfig +6 -0

+config RCAR_GYRO_ADC
+	tristate "Renesas R-Car GyroADC driver"
+	depends on ARCH_RCAR_GEN2 || (ARM && COMPILE_TEST)
+	help
+	  Say yes here to build support for the GyroADC found in Renesas
+	  R-Car Gen2 SoCs.

Put a bit more detail here perhaps - it's not really an ADC afterall but a rather dumb spi offload engine.

I am so borrowing this one :)

If it was slightly smarter I'd suggest

Quoted 2 lines

supporting it through that infrastructure. That would require changes in every relevant driver though so not terribly elegant.

Yeah, I had that discussion with Lars and Mark Brown already :)

Quoted 130 lines

Quoted 118 lines

drivers/iio/adc/Kconfig +4 -0

+
+	  To compile this driver as a module, choose M here: the
+	  module will be called rcar-gyroadc.
+
 config ROCKCHIP_SARADC
 	tristate "Rockchip SARADC driver"
 	depends on ARCH_ROCKCHIP || (ARM && COMPILE_TEST)

drivers/iio/adc/Makefile +1 -0

index 7a40c04c311f..13db7c2bffc8 100644
@@ -39,6 +39,7 @@ obj-$(CONFIG_NAU7802) += nau7802.o
 obj-$(CONFIG_PALMAS_GPADC) += palmas_gpadc.o
 obj-$(CONFIG_QCOM_SPMI_IADC) += qcom-spmi-iadc.o
 obj-$(CONFIG_QCOM_SPMI_VADC) += qcom-spmi-vadc.o
+obj-$(CONFIG_RCAR_GYRO_ADC) += rcar-gyroadc.o
 obj-$(CONFIG_ROCKCHIP_SARADC) += rockchip_saradc.o
 obj-$(CONFIG_STX104) += stx104.o
 obj-$(CONFIG_TI_ADC081C) += ti-adc081c.o

drivers/iio/adc/rcar-gyroadc.c new file +93 -0

new file mode 100644
index 000000000000..14f139613e1c
@@ -0,0 +1,531 @@
+/*
+ * Renesas R-Car GyroADC driver
+ *
+ * Copyright 2016 Marek Vasut <[email protected]>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/delay.h>
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/io.h>
+#include <linux/clk.h>
+#include <linux/of.h>
+#include <linux/of_irq.h>
+#include <linux/regulator/consumer.h>
+#include <linux/of_platform.h>
+#include <linux/err.h>
+#include <linux/pm_runtime.h>
+
+#include <linux/iio/iio.h>
+#include <linux/iio/buffer.h>
+#include <linux/iio/sysfs.h>
+#include <linux/iio/trigger.h>
+
+/* GyroADC registers. */
+#define RCAR_GYROADC_MODE_SELECT		0x00
+#define RCAR_GYROADC_MODE_SELECT_1_MB88101A	0x0
+#define RCAR_GYROADC_MODE_SELECT_2_ADCS7476	0x1
+#define RCAR_GYROADC_MODE_SELECT_3_MAX1162	0x3
+
+#define RCAR_GYROADC_START_STOP			0x04
+#define RCAR_GYROADC_START_STOP_START		BIT(0)
+
+#define RCAR_GYROADC_CLOCK_LENGTH		0x08
+#define RCAR_GYROADC_1_25MS_LENGTH		0x0c
+
+#define RCAR_GYROADC_REALTIME_DATA(ch)		(0x10 + ((ch) * 4))
+#define RCAR_GYROADC_100MS_ADDED_DATA(ch)	(0x30 + ((ch) * 4))
+#define RCAR_GYROADC_10MS_AVG_DATA(ch)		(0x50 + ((ch) * 4))
+
+#define RCAR_GYROADC_FIFO_STATUS		0x70
+#define RCAR_GYROADC_FIFO_STATUS_EMPTY(ch)	BIT(0 + (4 * (ch)))
+#define RCAR_GYROADC_FIFO_STATUS_FULL(ch)	BIT(1 + (4 * (ch)))
+#define RCAR_GYROADC_FIFO_STATUS_ERROR(ch)	BIT(2 + (4 * (ch)))
+
+#define RCAR_GYROADC_INTR			0x74
+#define RCAR_GYROADC_INTR_INT			BIT(0)
+
+#define RCAR_GYROADC_INTENR			0x78
+#define RCAR_GYROADC_INTENR_INTEN		BIT(0)
+
+#define RCAR_GYROADC_SAMPLE_RATE		800	/* Hz */
+
+enum rcar_gyroadc_model {
+	RCAR_GYROADC_MODEL_DEFAULT,
+	RCAR_GYROADC_MODEL_R8A7792,
+};
+
+struct rcar_gyroadc {
+	struct device			*dev;
+	void __iomem			*regs;
+	struct clk			*iclk;
+	struct regulator		*vref[8];
+	unsigned int			num_channels;
+	enum rcar_gyroadc_model		model;
+	unsigned int			mode;
+	unsigned int			sample_width;
+	u32				buffer[8];
+};
+
+static void rcar_gyroadc_hw_init(struct rcar_gyroadc *priv)
+{
+	const unsigned long clk_mhz = clk_get_rate(priv->iclk) / 1000000;
+	const unsigned long clk_mul =
+		(priv->mode == RCAR_GYROADC_MODE_SELECT_1_MB88101A) ? 10 : 5;
+
+	/* Stop the GyroADC. */
+	writel(0, priv->regs + RCAR_GYROADC_START_STOP);
+
+	/* Disable IRQ on V2H. */
+	if (priv->model == RCAR_GYROADC_MODEL_R8A7792)
+		writel(0, priv->regs + RCAR_GYROADC_INTENR);

drivers/iio/adc/rcar-gyroadc.c line 103

Quoted 10 lines

drivers/iio/adc/rcar-gyroadc.c new file +10 -0

+
+	/* Set mode and timing. */
+	writel(priv->mode, priv->regs + RCAR_GYROADC_MODE_SELECT);
+	writel(clk_mhz * clk_mul, priv->regs + RCAR_GYROADC_CLOCK_LENGTH);
+	writel(clk_mhz * 1250, priv->regs + RCAR_GYROADC_1_25MS_LENGTH);
+
+	/*
+	 * We can possibly turn the sampling on/off on-demand to reduce power
+	 * consumption, but for the sake of quick availability of samples, we
+	 * don't do it now.

Typically, if you want to do this, do it with runtime_pm and use the auto suspend stuff. Can work well.

Quoted 2 lines

You mean keep sampling and let the runtime PM just turn the clock to this block on/off ?

Possibly, or possibly let runtime pm autosuspend stuff actually stop the sampling if it doesn't happen for 'a while'.

Quoted 468 lines

Quoted 32 lines

Quoted 32 lines

drivers/iio/adc/rcar-gyroadc.c new file +32 -0

+	 */
+	writel(RCAR_GYROADC_START_STOP_START,
+	       priv->regs + RCAR_GYROADC_START_STOP);
+
+	/* Wait for the first conversion to complete. */
+	udelay(1250);
+}
+
+#define RCAR_GYROADC_CHAN(_idx) {				\
+	.type			= IIO_VOLTAGE,			\
+	.indexed		= 1,				\
+	.channel		= (_idx),			\
+	.info_mask_separate	= BIT(IIO_CHAN_INFO_RAW) |	\
+				  BIT(IIO_CHAN_INFO_SCALE),	\
+	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SAMP_FREQ), \
+}
+
+static const struct iio_chan_spec rcar_gyroadc_iio_channels_1[] = {
+	RCAR_GYROADC_CHAN(0),
+	RCAR_GYROADC_CHAN(1),
+	RCAR_GYROADC_CHAN(2),
+	RCAR_GYROADC_CHAN(3),
+};
+
+static const struct iio_chan_spec rcar_gyroadc_iio_channels_2[] = {
+	RCAR_GYROADC_CHAN(0),
+	RCAR_GYROADC_CHAN(1),
+	RCAR_GYROADC_CHAN(2),
+	RCAR_GYROADC_CHAN(3),
+	RCAR_GYROADC_CHAN(4),
+	RCAR_GYROADC_CHAN(5),
+	RCAR_GYROADC_CHAN(6),

Quoted 8 lines

drivers/iio/adc/rcar-gyroadc.c line 141

Quoted 6 lines

drivers/iio/adc/rcar-gyroadc.c new file +6 -0

+	RCAR_GYROADC_CHAN(7),
+};
+
+/*
+ * NOTE: The data we receive in mode 3 from MAX1162 have MSByte = 0,
+ *       therefore we only use 16bit realbits here instead of 24.

Umm. That would be a fair comment if realbits was set at all! With what you are currently supporting it shouldn't be.

Dropped, thanks.

Quoted 43 lines

Quoted 43 lines

drivers/iio/adc/rcar-gyroadc.c new file +43 -0

+ */
+static const struct iio_chan_spec rcar_gyroadc_iio_channels_3[] = {
+	RCAR_GYROADC_CHAN(0),
+	RCAR_GYROADC_CHAN(1),
+	RCAR_GYROADC_CHAN(2),
+	RCAR_GYROADC_CHAN(3),
+	RCAR_GYROADC_CHAN(4),
+	RCAR_GYROADC_CHAN(5),
+	RCAR_GYROADC_CHAN(6),
+	RCAR_GYROADC_CHAN(7),
+};
+
+static int rcar_gyroadc_read_raw(struct iio_dev *indio_dev,
+				 struct iio_chan_spec const *chan,
+				 int *val, int *val2, long mask)
+{
+	struct rcar_gyroadc *priv = iio_priv(indio_dev);
+	struct regulator *consumer = priv->vref[chan->channel];
+	unsigned int datareg = RCAR_GYROADC_REALTIME_DATA(chan->channel);
+	unsigned int vref;
+	int ret;
+
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW:
+		if (chan->type != IIO_VOLTAGE)
+			return -EINVAL;
+
+		/* Channel not connected. */
+		if (!consumer)
+			return -EINVAL;
+
+		ret = iio_device_claim_direct_mode(indio_dev);
+		if (ret)
+			return ret;
+
+		*val = readl(priv->regs + datareg);
+		*val &= BIT(priv->sample_width) - 1;
+
+		iio_device_release_direct_mode(indio_dev);
+
+		return IIO_VAL_INT;
+	case IIO_CHAN_INFO_SCALE:
+		/* Channel not connected. */

Quoted 8 lines

drivers/iio/adc/rcar-gyroadc.c line 190

Quoted 6 lines

drivers/iio/adc/rcar-gyroadc.c new file +6 -0

+		if (!consumer)
+			return -EINVAL;
+
+		vref = regulator_get_voltage(consumer);
+		*val = 0;
+		*val2 = DIV_ROUND_CLOSEST(vref * 1000, 0x10000);

spacing is a bit variable. Sometimes you leave a line before the return, sometimes you don't. Pick one or the other and it'll read slightly better!

A newline before return it is, it makes things a bit more readable IMO.

Quoted 155 lines

Quoted 94 lines

drivers/iio/adc/rcar-gyroadc.c new file +94 -0

+		return IIO_VAL_INT_PLUS_NANO;
+	case IIO_CHAN_INFO_SAMP_FREQ:
+		*val = RCAR_GYROADC_SAMPLE_RATE;
+		return IIO_VAL_INT;
+	default:
+		return -EINVAL;
+	}
+}
+
+static int rcar_gyroadc_reg_access(struct iio_dev *indio_dev,
+				   unsigned int reg, unsigned int writeval,
+				   unsigned int *readval)
+{
+	struct rcar_gyroadc *priv = iio_priv(indio_dev);
+	unsigned int maxreg = RCAR_GYROADC_FIFO_STATUS;
+
+	if (readval == NULL)
+		return -EINVAL;
+
+	if (reg % 4)
+		return -EINVAL;
+
+	/* Handle the V2H case with extra interrupt block. */
+	if (priv->model == RCAR_GYROADC_MODEL_R8A7792)
+		maxreg = RCAR_GYROADC_INTENR;
+
+	if (reg > maxreg)
+		return -EINVAL;
+
+	*readval = readl(priv->regs + reg);
+
+	return 0;
+}
+
+static const struct iio_info rcar_gyroadc_iio_info = {
+	.driver_module		= THIS_MODULE,
+	.read_raw		= rcar_gyroadc_read_raw,
+	.debugfs_reg_access	= rcar_gyroadc_reg_access,
+};
+
+static const struct of_device_id rcar_gyroadc_match[] = {
+	{
+		/* R-Car compatible GyroADC */
+		.compatible	= "renesas,rcar-gyroadc",
+		.data		= (void *)RCAR_GYROADC_MODEL_DEFAULT,
+	}, {
+		/* R-Car V2H specialty with interrupt registers. */
+		.compatible	= "renesas,r8a7792-gyroadc",
+		.data		= (void *)RCAR_GYROADC_MODEL_R8A7792,
+	}, {
+		/* sentinel */
+	}
+};
+
+MODULE_DEVICE_TABLE(of, rcar_gyroadc_match);
+
+static const struct of_device_id rcar_gyroadc_child_match[] = {
+	/* Mode 1 ADCs */
+	{
+		.compatible	= "fujitsu,mb88101a",
+		.data		= (void *)RCAR_GYROADC_MODE_SELECT_1_MB88101A,
+	},
+	/* Mode 2 ADCs */
+	{
+		.compatible	= "ti,adcs7476",
+		.data		= (void *)RCAR_GYROADC_MODE_SELECT_2_ADCS7476,
+	}, {
+		.compatible	= "ti,adc121",
+		.data		= (void *)RCAR_GYROADC_MODE_SELECT_2_ADCS7476,
+	}, {
+		.compatible	= "adi,ad7476",
+		.data		= (void *)RCAR_GYROADC_MODE_SELECT_2_ADCS7476,
+	},
+	/* Mode 3 ADCs */
+	{
+		.compatible	= "maxim,max1162",
+		.data		= (void *)RCAR_GYROADC_MODE_SELECT_3_MAX1162,
+	}, {
+		.compatible	= "maxim,max11100",
+		.data		= (void *)RCAR_GYROADC_MODE_SELECT_3_MAX1162,
+	},
+	{ /* sentinel */ }
+};
+
+static int rcar_gyroadc_parse_subdevs(struct iio_dev *indio_dev)
+{
+	const struct of_device_id *of_id;
+	const struct iio_chan_spec *channels;
+	struct rcar_gyroadc *priv = iio_priv(indio_dev);
+	struct device *dev = priv->dev;
+	struct device_node *np = dev->of_node;
+	struct device_node *child;
+	struct regulator *vref;
+	unsigned int reg, maxreg;

drivers/iio/adc/rcar-gyroadc.c line 294

Quoted 10 lines

drivers/iio/adc/rcar-gyroadc.c new file +10 -0

+	unsigned int adcmode, childmode;
+	unsigned int sample_width;
+	unsigned int num_channels;
+	int ret, first = 1;
+
+	for_each_child_of_node(np, child) {
+		of_id = of_match_node(rcar_gyroadc_child_match, child);
+		if (!of_id) {
+			dev_err(dev, "Ignoring unsupported ADC \"%s\".",
+				child->name);

This is the only case that should result in a continue.

Quoted 37 lines

drivers/iio/adc/rcar-gyroadc.c new file +37 -0

+			continue;
+		}
+
+		ret = of_property_read_u32(child, "reg", &reg);
+		if (ret) {
+			dev_err(dev,
+				"Failed to get child reg property of ADC \"%s\".\n",
+				child->name);
+			continue;
+		}
+
+		childmode = (unsigned int)of_id->data;
+		switch (childmode) {
+		case RCAR_GYROADC_MODE_SELECT_1_MB88101A:
+			maxreg = 4;
+			sample_width = 12;
+			channels = rcar_gyroadc_iio_channels_1;
+			num_channels = ARRAY_SIZE(rcar_gyroadc_iio_channels_1);
+			break;
+		case RCAR_GYROADC_MODE_SELECT_2_ADCS7476:
+			maxreg = 8;
+			sample_width = 15;
+			channels = rcar_gyroadc_iio_channels_2;
+			num_channels = ARRAY_SIZE(rcar_gyroadc_iio_channels_2);
+			break;
+		case RCAR_GYROADC_MODE_SELECT_3_MAX1162:
+			maxreg = 8;
+			sample_width = 16;
+			channels = rcar_gyroadc_iio_channels_3;
+			num_channels = ARRAY_SIZE(rcar_gyroadc_iio_channels_3);
+			break;
+		}
+
+		/* Channel number is too high. */
+		if (reg >= maxreg) {
+			dev_err(dev,
+				"Only %i channels supported with %s, but reg = <%i>, ignoring.\n",

drivers/iio/adc/rcar-gyroadc.c line 341

Quoted 10 lines

drivers/iio/adc/rcar-gyroadc.c new file +10 -0

+				maxreg, child->name, reg);
+			continue;
+		}
+
+		/* Child node selected different mode than the rest. */
+		if (!first && (adcmode != childmode)) {
+			dev_err(dev,
+				"Channel %i uses different ADC mode than the rest, ignoring.\n",
+				reg);
+			continue;

Fail hard - not softly - I'd expect the probe to completely fail if the device tree is invalid in this way.

Quoted 1 line

Same is true for other conditions above. Don't paper over the issue please.

OK

Quoted 7 lines

Quoted 7 lines

drivers/iio/adc/rcar-gyroadc.c new file +7 -0

+		}
+
+		/* Channel is valid, grab the regulator. */
+		dev->of_node = child;
+		vref = devm_regulator_get_optional(dev, "vref");
+		dev->of_node = np;
+		if (IS_ERR(vref)) {

Quoted 8 lines

drivers/iio/adc/rcar-gyroadc.c line 354

Quoted 6 lines

drivers/iio/adc/rcar-gyroadc.c new file +6 -0

+			/*
+			 * Regulator is not present, which means the channel
+			 * supply is not connected.
+			 */
+			dev_dbg(dev, "Channel %i 'vref' supply not connected\n",
+				reg);

Error out rather than carrying on to try other channels. If the device tree is invalid we want to know and fail hard.

OK

Quoted 121 lines

Quoted 121 lines

drivers/iio/adc/rcar-gyroadc.c new file +121 -0

+			continue;
+		}
+
+		priv->vref[reg] = vref;
+
+		if (!first)
+			continue;
+
+		/* First child node which passed sanity tests. */
+		adcmode = childmode;
+		first = 0;
+
+		priv->num_channels = maxreg;
+		priv->mode = childmode;
+		priv->sample_width = sample_width;
+
+		indio_dev->channels = channels;
+		indio_dev->num_channels = num_channels;
+	}
+
+	if (first) {
+		dev_err(dev, "No valid ADC channels found, aborting.\n");
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static void rcar_gyroadc_deinit_supplies(struct iio_dev *indio_dev)
+{
+	struct rcar_gyroadc *priv = iio_priv(indio_dev);
+	unsigned int i;
+
+	for (i = 0; i < priv->num_channels; i++) {
+		if (!priv->vref[i])
+			continue;
+
+		regulator_disable(priv->vref[i]);
+	}
+}
+
+static int rcar_gyroadc_init_supplies(struct iio_dev *indio_dev)
+{
+	struct rcar_gyroadc *priv = iio_priv(indio_dev);
+	struct device *dev = priv->dev;
+	unsigned int i;
+	int ret;
+
+	for (i = 0; i < priv->num_channels; i++) {
+		if (!priv->vref[i])
+			continue;
+
+		ret = regulator_enable(priv->vref[i]);
+		if (ret) {
+			dev_err(dev, "Failed to enable regulator %i (ret=%i)\n",
+				i, ret);
+			goto err;
+		}
+	}
+
+	return 0;
+
+err:
+	rcar_gyroadc_deinit_supplies(indio_dev);
+	return ret;
+}
+
+static int rcar_gyroadc_probe(struct platform_device *pdev)
+{
+	const struct of_device_id *of_id =
+		of_match_device(rcar_gyroadc_match, &pdev->dev);
+	struct device *dev = &pdev->dev;
+	struct rcar_gyroadc *priv;
+	struct iio_dev *indio_dev;
+	struct resource *mem;
+	int ret;
+
+	indio_dev = devm_iio_device_alloc(dev, sizeof(*priv));
+	if (!indio_dev) {
+		dev_err(dev, "Failed to allocate IIO device.\n");
+		return -ENOMEM;
+	}
+
+	priv = iio_priv(indio_dev);
+	priv->dev = dev;
+
+	mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	priv->regs = devm_ioremap_resource(dev, mem);
+	if (IS_ERR(priv->regs))
+		return PTR_ERR(priv->regs);
+
+	priv->iclk = devm_clk_get(dev, "if");
+	if (IS_ERR(priv->iclk)) {
+		ret = PTR_ERR(priv->iclk);
+		if (ret != -EPROBE_DEFER)
+			dev_err(dev, "Failed to get IF clock (ret=%i)\n", ret);
+		return ret;
+	}
+
+	ret = rcar_gyroadc_parse_subdevs(indio_dev);
+	if (ret)
+		return ret;
+
+	ret = rcar_gyroadc_init_supplies(indio_dev);
+	if (ret)
+		return ret;
+
+	priv->model = (enum rcar_gyroadc_model)of_id->data;
+
+	platform_set_drvdata(pdev, indio_dev);
+
+	indio_dev->name = dev_name(dev);
+	indio_dev->dev.parent = dev;
+	indio_dev->dev.of_node = pdev->dev.of_node;
+	indio_dev->info = &rcar_gyroadc_iio_info;
+	indio_dev->modes = INDIO_DIRECT_MODE;
+
+	pm_runtime_enable(dev);
+	pm_runtime_get_sync(dev);
+
+	ret = clk_prepare_enable(priv->iclk);

Quoted 8 lines

drivers/iio/adc/rcar-gyroadc.c line 481

Quoted 6 lines

drivers/iio/adc/rcar-gyroadc.c new file +6 -0

+	if (ret) {
+		dev_err(dev, "Could not prepare or enable the IF clock.\n");
+		goto error_clk_if_enable;
+	}
+
+	rcar_gyroadc_hw_init(priv);

This doesn't seem to be unwound on a failure in iio_device_register in particular the sampling isn't stopped on an error occuring.

Ah, nice catch and fixed.

Quoted 21 lines

Quoted 21 lines

drivers/iio/adc/rcar-gyroadc.c new file +21 -0

+
+	ret = iio_device_register(indio_dev);
+	if (ret) {
+		dev_err(dev, "Couldn't register IIO device.\n");
+		goto error_iio_device_register;
+	}
+
+	return 0;
+
+error_iio_device_register:
+	clk_disable_unprepare(priv->iclk);
+error_clk_if_enable:
+	pm_runtime_put(dev);
+	pm_runtime_disable(dev);
+	rcar_gyroadc_deinit_supplies(indio_dev);
+	return ret;
+}
+
+static int rcar_gyroadc_remove(struct platform_device *pdev)
+{
+	struct iio_dev *indio_dev = platform_get_drvdata(pdev);

Quoted 8 lines

drivers/iio/adc/rcar-gyroadc.c line 506

Quoted 4 lines

drivers/iio/adc/rcar-gyroadc.c new file +4 -0

+	struct rcar_gyroadc *priv = iio_priv(indio_dev);
+	struct device *dev = priv->dev;
+
+	/* Stop sampling */

I'd slightly prefer to see this wrapped up in a function that makes it clear it is unwinding the _init() call made in probe.
Also the ordering of remove should be the reverse of probe which I think means this should be somewhat later.

Yup and both fixed.

Quoted 19 lines

Quoted 19 lines

drivers/iio/adc/rcar-gyroadc.c new file +18 -0

+	writel(0, priv->regs + RCAR_GYROADC_START_STOP);
 
+
+	iio_device_unregister(indio_dev);
+	clk_disable_unprepare(priv->iclk);
+	pm_runtime_put(dev);
+	pm_runtime_disable(dev);
+	rcar_gyroadc_deinit_supplies(indio_dev);
+
+	return 0;
+}
+
+static struct platform_driver rcar_gyroadc_driver = {
+	.probe          = rcar_gyroadc_probe,
+	.remove         = rcar_gyroadc_remove,
+	.driver         = {
+		.name		= "rcar-gyroadc",
+		.of_match_table	= rcar_gyroadc_match,
+	},

Quoted 8 lines

drivers/iio/adc/rcar-gyroadc.c line 531

Quoted 8 lines

drivers/iio/adc/rcar-gyroadc.c new file +7 -0

+};
+
+module_platform_driver(rcar_gyroadc_driver);
+
+MODULE_AUTHOR("Marek Vasut <[email protected]>");
+MODULE_DESCRIPTION("Renesas R-Car GyroADC driver");
+MODULE_LICENSE("GPL");

Thanks!