Support ROHM BD79124 ADC

Support ROHM BD79124 ADC.

This series adds also couple of IIO ADC helper functions for parsing the channel information from the device tree. There are also new helpers included for iterating and counting firmware child nodes with a specific name.

Series does also convert couple of drivers to use these helpers. The rzg2l_adc and the sun20i-gpadc are converted to use the new ADC helper.

The gianfar driver under net and the thp7312 under media/i2c are added as first users of the newly added "named child node" -helpers.

There has been some discussion about how useful these ADC helpers are, and whether they should support also differential and single ended channel configurations. This version does not include support for those - with the benefit of reduced complexity and easier to use API.

NOTE: Patches 4,5,9 and 10 are untested as I lack of relevant HW. They have been compile tested only.

The ROHM BD79124 ADC itself is quite usual stuff. 12-bit, 8-channel ADC with threshold monitoring.

Except that:
- each ADC input pin can be configured as a general purpose output.
- manually starting an ADC conversion and reading the result would require the I2C _master_ to do clock stretching(!) for the duration of the conversion... Let's just say this is not well supported.
- IC supports 'autonomous measurement mode' and storing latest results to the result registers. This mode is used by the driver due to the "peculiar" I2C when doing manual reads.

Furthermore, the ADC uses this continuous autonomous measuring, and the IC keeps producing new 'out of window' IRQs if measurements are out of window - the driver disables the event for 1 seconds when sending it to user. This prevents generating storm of events

Revision history:
v5 => v6:
- Drop applied patch
- Add *_for_each_named_child_* iterators
- Add a patch converting the thp7312 driver to use the new helper
- Styling and minor things pointed by reviewers

v4 => v5: Fixes as per various review comments. Most notably:
- Drop the patch making the TI's ADC driver to respect device tree.
- Add (RFC) patch converting gianfar driver to use new name child-node counting API as suggested by Andy.
- Add fwnode_get_child_node_count_named() as suggested by Rob.
- rebase to v6.14-rc5
More accurate changelog in individual patches.

v3 => v4:
- Drop the ADC helper support for differential channels
- Drop the ADC helper for getting only channel IDs by fwnode.
- "Promote" the function counting the number of child nodes with a specific name to the property.h (As suggested by Jonathan).
- Add ADC helpers to a namespace.
- Rebase on v6.14-rc3
- More minor changes described in individual patches.

v2 => v3:
- Restrict BD79124 channel numbers as suggested by Conor and add Conor's Reviewed-by tag.
- Support differential and single-ended inputs
- Convert couple of existing drivers to use the added ADC helpers
- Minor fixes based on reviews
Link to v2:
https://lore.kernel.org/all/[email protected]/

RFC v1 => v2:
- Drop MFD and pinmux.
- Automatically re-enable events after 1 second.
- Export fwnode parsing helpers for finding the ADC channels.

---

Matti Vaittinen (10):
dt-bindings: ROHM BD79124 ADC/GPO
property: Add functions to iterate named child
iio: adc: add helpers for parsing ADC nodes
iio: adc: rzg2l_adc: Use adc-helpers
iio: adc: sun20i-gpadc: Use adc-helpers
iio: adc: Support ROHM BD79124 ADC
MAINTAINERS: Add IIO ADC helpers
MAINTAINERS: Add ROHM BD79124 ADC/GPO
net: gianfar: Use device_get_child_node_count_named()
media: thp7312: Use helper for iterating named child nodes

 .../bindings/iio/adc/rohm,bd79124.yaml        |  114 ++
 MAINTAINERS                                   |   12 +
 drivers/base/property.c                       |   54 +
 drivers/iio/adc/Kconfig                       |   17 +
 drivers/iio/adc/Makefile                      |    3 +
 drivers/iio/adc/industrialio-adc.c            |   79 ++
 drivers/iio/adc/rohm-bd79124.c                | 1106 +++++++++++++++++
 drivers/iio/adc/rzg2l_adc.c                   |   38 +-
 drivers/iio/adc/sun20i-gpadc-iio.c            |   38 +-
 drivers/media/i2c/thp7312.c                   |    8 +-
 drivers/net/ethernet/freescale/gianfar.c      |   17 +-
 include/linux/iio/adc-helpers.h               |   27 +
 include/linux/property.h                      |   20 +
 13 files changed, 1471 insertions(+), 62 deletions(-)
 create mode 100644 Documentation/devicetree/bindings/iio/adc/rohm,bd79124.yaml
 create mode 100644 drivers/iio/adc/industrialio-adc.c
 create mode 100644 drivers/iio/adc/rohm-bd79124.c
 create mode 100644 include/linux/iio/adc-helpers.h

base-commit: 7eb172143d5508b4da468ed59ee857c6e5e01da6

2.48.1

Add binding document for the ROHM BD79124 ADC / GPO.

ROHM BD79124 is a 8-channel, 12-bit ADC. The input pins can also be used as general purpose outputs.

---
Revision history:
v3 =>
- No changes
v2 => v3:
- Restrict channel numbers to 0-7 as suggested by Conor
RFC v1 => v2:
- drop MFD and represent directly as ADC
- drop pinmux and treat all non ADC channel pins as GPOs

---
 .../bindings/iio/adc/rohm,bd79124.yaml        | 114 ++++++++++++++++++
 1 file changed, 114 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/iio/adc/rohm,bd79124.yaml

new file mode 100644
index 000000000000..503285823376
@@ -0,0 +1,114 @@
+# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/iio/adc/rohm,bd79124.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: ROHM BD79124 ADC/GPO
+
+maintainers:
+  - Matti Vaittinen <[email protected]>
+
+description: |
+  The ROHM BD79124 is a 12-bit, 8-channel, SAR ADC. The ADC supports
+  an automatic measurement mode, with an alarm interrupt for out-of-window
+  measurements. ADC input pins can be also configured as general purpose
+  outputs.
+
+properties:
+  compatible:
+    const: rohm,bd79124
+
+  reg:
+    description:
+      I2C slave address.
+    maxItems: 1
+
+  interrupts:
+    maxItems: 1
+
+  gpio-controller: true
+
+  "#gpio-cells":
+    const: 1
+    description:
+      The pin number.
+
+  vdd-supply: true
+
+  iovdd-supply: true
+
+  "#address-cells":
+    const: 1
+
+  "#size-cells":
+    const: 0
+
+patternProperties:
+  "^channel@[0-7]+$":
+    type: object
+    $ref: /schemas/iio/adc/adc.yaml#
+    description: Represents ADC channel.
+
+    properties:
+      reg:
+        description: AIN pin number
+        minimum: 0
+        maximum: 7
+
+    required:
+      - reg
+
+    additionalProperties: false
+
+required:
+  - compatible
+  - reg
+  - iovdd-supply
+  - vdd-supply
+
+additionalProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/interrupt-controller/irq.h>
+    #include <dt-bindings/leds/common.h>
+    i2c {
+        #address-cells = <1>;
+        #size-cells = <0>;
+        adc: adc@10 {
+            compatible = "rohm,bd79124";
+            reg = <0x10>;
+
+            interrupt-parent = <&gpio1>;
+            interrupts = <29 8>;
+
+            vdd-supply = <&dummyreg>;
+            iovdd-supply = <&dummyreg>;
+
+            #address-cells = <1>;
+            #size-cells = <0>;
+
+            channel@0 {
+                reg = <0>;
+            };
+            channel@1 {
+                reg = <1>;
+            };
+            channel@2 {
+                reg = <2>;
+            };
+            channel@3 {
+                reg = <3>;
+            };
+            channel@4 {
+                reg = <4>;
+            };
+            channel@5 {
+                reg = <5>;
+            };
+            channel@6 {
+                reg = <6>;
+            };
+        };
+    };

2.48.1

There are a few use-cases where child nodes with a specific name need to be parsed. Code like:

fwnode_for_each_child_node()

	if (fwnode_name_eq())
		...

can be found from a various drivers/subsystems. Adding a macro for this can simplify things a bit.

In a few cases the data from the found nodes is later added to an array, which is allocated based on the number of found nodes. One example of such use is the IIO subsystem's ADC channel nodes, where the relevant nodes are named as channel[@N].

Add a helpers for iterating and counting device's sub-nodes with certain name instead, of open-coding this in every user.

---
Revision history:
v5 => v6:
- Add helpers to also iterate through the nodes.
v4 => v5:
- Use given name instead of string 'channel' when counting the nodes
- Add also fwnode_get_child_node_count_named() as suggested by Rob.
v3 => v4:
- New patch as suggested by Jonathan, see discussion in:
https://lore.kernel.org/lkml/20250223161338.5c896280@jic23-huawei/

Please note, the checkpatch.pl was not happy about the for_each...() macros. I tried to make them to follow the existing convention. I am open to suggestions how to improve.

---
 drivers/base/property.c  | 54 ++++++++++++++++++++++++++++++++++++++++
 include/linux/property.h | 20 +++++++++++++++
 2 files changed, 74 insertions(+)

index c1392743df9c..335262a894f4 100644
@@ -945,6 +945,60 @@ unsigned int device_get_child_node_count(const struct device *dev)
 }
 EXPORT_SYMBOL_GPL(device_get_child_node_count);
 
+/**
+ * fwnode_get_named_child_node_count - number of child nodes with given name
+ * @fwnode: Node which child nodes are counted.
+ * @name: String to match child node name against.
+ *
+ * Scan child nodes and count all the nodes with a specific name. Return the
+ * number of found nodes. Potential '@number' -ending for scanned names is
+ * ignored. Eg,
+ * device_get_child_node_count(dev, "channel");
+ * would match all the nodes:
+ * channel { }, channel@0 {}, channel@0xabba {}...
+ *
+ * Return: the number of child nodes with a matching name for a given device.
+ */
+unsigned int fwnode_get_named_child_node_count(const struct fwnode_handle *fwnode,
+					       const char *name)
+{
+	struct fwnode_handle *child;
+	unsigned int count = 0;
+
+	fwnode_for_each_named_child_node(fwnode, child, name)
+		count++;
+
+	return count;
+}
+EXPORT_SYMBOL_GPL(fwnode_get_named_child_node_count);
+
+/**
+ * device_get_named_child_node_count - number of child nodes with given name
+ * @dev: Device to count the child nodes for.
+ * @name: String to match child node name against.
+ *
+ * Scan device's child nodes and find all the nodes with a specific name and
+ * return the number of found nodes. Potential '@number' -ending for scanned
+ * names is ignored. Eg,
+ * device_get_child_node_count(dev, "channel");
+ * would match all the nodes:
+ * channel { }, channel@0 {}, channel@0xabba {}...
+ *
+ * Return: the number of child nodes with a matching name for a given device.
+ */
+unsigned int device_get_named_child_node_count(const struct device *dev,
+					       const char *name)
+{
+	struct fwnode_handle *child;
+	unsigned int count = 0;
+
+	device_for_each_named_child_node(dev, child, name)
+		count++;
+
+	return count;
+}
+EXPORT_SYMBOL_GPL(device_get_named_child_node_count);
+
 bool device_dma_supported(const struct device *dev)
 {
 	return fwnode_call_bool_op(dev_fwnode(dev), device_dma_supported);

index e214ecd241eb..6dd9ae83e9a5 100644
@@ -167,10 +167,18 @@ struct fwnode_handle *fwnode_get_next_available_child_node(
 	for (child = fwnode_get_next_child_node(fwnode, NULL); child;	\
 	     child = fwnode_get_next_child_node(fwnode, child))
 
+#define fwnode_for_each_named_child_node(fwnode, child, name)		\
+		fwnode_for_each_child_node(fwnode, child)		\
+			if (!fwnode_name_eq(child, name)) { } else
+
 #define fwnode_for_each_available_child_node(fwnode, child)		       \
 	for (child = fwnode_get_next_available_child_node(fwnode, NULL); child;\
 	     child = fwnode_get_next_available_child_node(fwnode, child))
 
+#define fwnode_for_each_available_named_child_node(fwnode, child, name)	\
+		fwnode_for_each_available_child_node(fwnode, child)	\
+			if (!fwnode_name_eq(child, name)) { } else
+
 struct fwnode_handle *device_get_next_child_node(const struct device *dev,
 						 struct fwnode_handle *child);
 

@@ -178,11 +186,19 @@ struct fwnode_handle *device_get_next_child_node(const struct device *dev,
 	for (child = device_get_next_child_node(dev, NULL); child;	\
 	     child = device_get_next_child_node(dev, child))
 
+#define device_for_each_named_child_node(dev, child, name)		\
+		device_for_each_child_node(dev, child)			\
+			if (!fwnode_name_eq(child, name)) { } else
+
 #define device_for_each_child_node_scoped(dev, child)			\
 	for (struct fwnode_handle *child __free(fwnode_handle) =	\
 		device_get_next_child_node(dev, NULL);			\
 	     child; child = device_get_next_child_node(dev, child))
 
+#define device_for_each_named_child_node_scoped(dev, child, name)	\
+		device_for_each_child_node_scoped(dev, child)		\
+			if (!fwnode_name_eq(child, name)) { } else
+
 struct fwnode_handle *fwnode_get_named_child_node(const struct fwnode_handle *fwnode,
 						  const char *childname);
 struct fwnode_handle *device_get_named_child_node(const struct device *dev,

@@ -209,6 +225,10 @@ int fwnode_irq_get(const struct fwnode_handle *fwnode, unsigned int index);
 int fwnode_irq_get_byname(const struct fwnode_handle *fwnode, const char *name);
 
 unsigned int device_get_child_node_count(const struct device *dev);
+unsigned int fwnode_get_named_child_node_count(const struct fwnode_handle *fwnode,
+					       const char *name);
+unsigned int device_get_named_child_node_count(const struct device *dev,
+					       const char *name);
 
 static inline int device_property_read_u8(const struct device *dev,
 					  const char *propname, u8 *val)

2.48.1

Almost good, I doubt we need the exported function for the device as it can be derived from the fwnode_*() API by supplying dev_fwnode(dev).

Perhaps we want also this for the completeness (other comments are below):

From f52dbbe97ff0cdf835eef29506e482433f0a50a9 Mon Sep 17 00:00:00 2001
From: Andy Shevchenko <[email protected]>
Date: Mon, 10 Mar 2025 16:20:35 +0200
Subject: [PATCH 1/1] device property: Split fwnode_get_child_node_count()

The new helper is introduced to allow counting the child firmware nodes of their parent without requiring a device to be passed. This also makes the fwnode and device property API more symmetrical with the rest.

---
 drivers/base/property.c  | 12 ++++++------
 include/linux/property.h |  7 ++++++-
 2 files changed, 12 insertions(+), 7 deletions(-)

index c1392743df9c..805f75b35115 100644
@@ -928,22 +928,22 @@ bool fwnode_device_is_available(const struct fwnode_handle *fwnode)
 EXPORT_SYMBOL_GPL(fwnode_device_is_available);
 
 /**
- * device_get_child_node_count - return the number of child nodes for device
- * @dev: Device to count the child nodes for
+ * fwnode_get_child_node_count - return the number of child nodes for a given firmware node
+ * @fwnode: Pointer to the parent firmware node
  *
- * Return: the number of child nodes for a given device.
+ * Return: the number of child nodes for a given firmware node.
  */
-unsigned int device_get_child_node_count(const struct device *dev)
+unsigned int fwnode_get_child_node_count(const struct fwnode_handle *fwnode)
 {
 	struct fwnode_handle *child;
 	unsigned int count = 0;
 
-	device_for_each_child_node(dev, child)
+	fwnode_for_each_child_node(fwnode, child)
 		count++;
 
 	return count;
 }
-EXPORT_SYMBOL_GPL(device_get_child_node_count);
+EXPORT_SYMBOL_GPL(fwnode_get_child_node_count);
 
 bool device_dma_supported(const struct device *dev)
 {

index e214ecd241eb..bc5bfc98176b 100644
@@ -208,7 +208,12 @@ DEFINE_FREE(fwnode_handle, struct fwnode_handle *, fwnode_handle_put(_T))
 int fwnode_irq_get(const struct fwnode_handle *fwnode, unsigned int index);
 int fwnode_irq_get_byname(const struct fwnode_handle *fwnode, const char *name);
 
-unsigned int device_get_child_node_count(const struct device *dev);
+unsigned int fwnode_get_child_node_count(const struct fwnode_handle *fwnode);
+
+static inline unsigned int device_get_child_node_count(const struct device *dev)
+{
+	return fwnode_get_child_node_count(dev_fwnode(dev));
+}
 
 static inline int device_property_read_u8(const struct device *dev,
 					  const char *propname, u8 *val)

...

checkpatch is known for false-positives and/or false-negatives.

...

You already have a return section below. Perhaps rephrase somehow?

Not sure how this "'@foo' -ending" part is being rendered in HTML/PDF... Also kernel-doc might be not happy with the @ character followed by an immediate text as it might be misinterpreted as a reference to a parameter.

E.g.,

(because it's the phrase in Latin: exempli gratia)

Shift right to make sure it's not a text, but a code, better even to use reST approach, i.e. (note additional leading space(s) and double colon):

* ignored. E.g.::
*
* fwnode_get_child_node_count(dev, "channel"); // you have a copy'n'paste typo
*
* would match all the nodes::
*
* ...
*

...

Similar comments as per above.

...

#define fwnode_for_each_named_child_node(fwnode, child, name)	\
	fwnode_for_each_child_node(fwnode, child)		\
		for_each_if(fwnode_name_eq(child, name))

					       const char *name);
unsigned int fwnode_get_named_child_node_count(const struct fwnode_handle *fwnode,
					       const char *name);

With Best Regards,
Andy Shevchenko

Unless this cycle goes long (i.e. an rc8) very unlikely I'll sneak the series in now due to lack of time to soak in next.

Nice - first time I've seen this :)

Jonathan

Hi Andy,

Thanks for the review.

...

I'll use for_each_if() if I'll have to rebase this to the v6.15-rc1.

Seems like you sent it as it's own series. I believe it's better that way.

Yours,
-- Matti

You also may update .clang-format.

With Best Regards,
Andy Shevchenko

Moi,

checkpatch.pl isn't always handling macros as well as it might. (It's just hard to parse C using regular expressions and in practice some simplifications end up being made.)

Sakari Ailus

There are ADC ICs which may have some of the AIN pins usable for other functions. These ICs may have some of the AIN pins wired so that they should not be used for ADC.

(Preferred?) way for marking pins which can be used as ADC inputs is to add corresponding channels@N nodes in the device tree as described in the ADC binding yaml.

Add couple of helper functions which can be used to retrieve the channel information from the device node.

---
Revision history:
v5 => v6:
- Adapt to changed fwnode helper names
- Fix spelling
v4 => v5:
- Inline iio_adc_device_num_channels()
- Fix Indenting function parameters
- Combine the max channel ID checks.
v3 => v4:
- Drop diff-channel support
- Drop iio_adc_device_channels_by_property()
- Add IIO_DEVICE namespace
- Move industrialio-adc.o to top of the Makefile
- Some styling as suggested by Andy
- Re-consider included headers
v2 => v3: Mostly based on review comments by Jonathan
- Support differential and single-ended channels
- Rename iio_adc_device_get_channels() as iio_adc_device_channels_by_property()
- Improve spelling
- Drop support for cases where DT comes from parent device's node
- Decrease loop indent by reverting node name check conditions
- Don't set 'chan->indexed' by number of channels to keep the interface consistent no matter how many channels are connected.
- Fix ID range check and related comment
RFC v1 => v2:
- New patch

---
 drivers/iio/adc/Kconfig            |  3 ++
 drivers/iio/adc/Makefile           |  2 +
 drivers/iio/adc/industrialio-adc.c | 79 ++++++++++++++++++++++++++++++
 include/linux/iio/adc-helpers.h    | 27 ++++++++++
 4 files changed, 111 insertions(+)
 create mode 100644 drivers/iio/adc/industrialio-adc.c
 create mode 100644 include/linux/iio/adc-helpers.h

index 849c90203071..37b70a65da6f 100644
@@ -6,6 +6,9 @@
 
 menu "Analog to digital converters"
 
+config IIO_ADC_HELPER
+	tristate
+
 config AB8500_GPADC
 	bool "ST-Ericsson AB8500 GPADC driver"
 	depends on AB8500_CORE && REGULATOR_AB8500

index ee19afba62b7..1c410f483029 100644
@@ -3,6 +3,8 @@
 # Makefile for IIO ADC drivers
 #
 
+obj-$(CONFIG_IIO_ADC_HELPER) += industrialio-adc.o
+
 # When adding new entries keep the list in alphabetical order
 obj-$(CONFIG_AB8500_GPADC) += ab8500-gpadc.o
 obj-$(CONFIG_AD_SIGMA_DELTA) += ad_sigma_delta.o

new file mode 100644
index 000000000000..56b092a2a4c4
@@ -0,0 +1,27 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+
+/*
+ * The industrial I/O ADC firmware property parsing helpers
+ *
+ * Copyright (c) 2025 Matti Vaittinen <[email protected]>
+ */
+
+#ifndef _INDUSTRIAL_IO_ADC_HELPERS_H_
+#define _INDUSTRIAL_IO_ADC_HELPERS_H_
+
+#include <linux/property.h>
+
+struct device;
+struct iio_chan_spec;
+
+static inline int iio_adc_device_num_channels(struct device *dev)
+{
+	return device_get_named_child_node_count(dev, "channel");
+}
+
+int devm_iio_adc_device_alloc_chaninfo_se(struct device *dev,
+					  const struct iio_chan_spec *template,
+					  int max_chan_id,
+					  struct iio_chan_spec **cs);
+
+#endif /* _INDUSTRIAL_IO_ADC_HELPERS_H_ */

2.48.1

The new devm_iio_adc_device_alloc_chaninfo() -helper is intended to help drivers avoid open-coding the for_each_node -loop for getting the channel IDs. The helper provides standard way to detect the ADC channel nodes (by the node name), and a standard way to convert the "reg" -properties to channel identification numbers, used in the struct iio_chan_spec. Furthermore, the helper can optionally check the found channel IDs are smaller than given maximum. This is useful for callers which later use the IDs for example for indexing a channel data array.

The original driver treated all found child nodes as channel nodes. The new helper requires channel nodes to be named channel[@N]. This should help avoid problems with devices which may contain also other but ADC child nodes. Quick grep from arch/* with the rzg2l_adc's compatible string didn't reveal any in-tree .dts with channel nodes named otherwise. Also, same grep shows all the .dts seem to have channel IDs between 0..num of channels.

Use the new helper.

---
Revision history:
v5 => v6:
- Commit message typofix
v4 => v5:
- Drop the diff-channel stuff from the commit message
v3 => v4:
- Adapt to 'drop diff-channel support' changes to ADC-helpers
- select ADC helpers in the Kconfig
- Rebased to 6.14-rc3 => channel type can no longer come from the template.

v2 => v3:
- New patch

The change is compile tested only!! Testing before applying is highly appreciated (as always!).

---
 drivers/iio/adc/Kconfig     |  1 +
 drivers/iio/adc/rzg2l_adc.c | 38 +++++++++++++++++--------------------
 2 files changed, 18 insertions(+), 21 deletions(-)

index 37b70a65da6f..e4933de0c366 100644
@@ -1222,6 +1222,7 @@ config RICHTEK_RTQ6056
 config RZG2L_ADC
 	tristate "Renesas RZ/G2L ADC driver"
 	depends on ARCH_RZG2L || COMPILE_TEST
+	select IIO_ADC_HELPER
 	help
 	  Say yes here to build support for the ADC found in Renesas
 	  RZ/G2L family.

index 883c167c0670..51c87b1bdc98 100644
@@ -11,6 +11,7 @@
 #include <linux/cleanup.h>
 #include <linux/completion.h>
 #include <linux/delay.h>
+#include <linux/iio/adc-helpers.h>
 #include <linux/iio/iio.h>
 #include <linux/interrupt.h>
 #include <linux/io.h>

@@ -324,21 +325,30 @@ static irqreturn_t rzg2l_adc_isr(int irq, void *dev_id)
 	return IRQ_HANDLED;
 }
 
+static const struct iio_chan_spec rzg2l_adc_chan_template = {
+	.indexed = 1,
+	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
+};
+
 static int rzg2l_adc_parse_properties(struct platform_device *pdev, struct rzg2l_adc *adc)
 {
 	const struct rzg2l_adc_hw_params *hw_params = adc->hw_params;
 	struct iio_chan_spec *chan_array;
 	struct rzg2l_adc_data *data;
-	unsigned int channel;
 	int num_channels;
-	int ret;
 	u8 i;
 
 	data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
 	if (!data)
 		return -ENOMEM;
 
-	num_channels = device_get_child_node_count(&pdev->dev);
+	num_channels = devm_iio_adc_device_alloc_chaninfo_se(&pdev->dev,
+						&rzg2l_adc_chan_template,
+						hw_params->num_channels - 1,
+						&chan_array);
+	if (num_channels < 0)
+		return num_channels;
+
 	if (!num_channels)
 		return dev_err_probe(&pdev->dev, -ENODEV, "no channel children\n");
 

@@ -346,26 +356,11 @@ static int rzg2l_adc_parse_properties(struct platform_device *pdev, struct rzg2l
 		return dev_err_probe(&pdev->dev, -EINVAL,
 				     "num of channel children out of range\n");
 
-	chan_array = devm_kcalloc(&pdev->dev, num_channels, sizeof(*chan_array),
-				  GFP_KERNEL);
-	if (!chan_array)
-		return -ENOMEM;
-
-	i = 0;
-	device_for_each_child_node_scoped(&pdev->dev, fwnode) {
-		ret = fwnode_property_read_u32(fwnode, "reg", &channel);
-		if (ret)
-			return ret;
-
-		if (channel >= hw_params->num_channels)
-			return -EINVAL;
+	for (i = 0; i < num_channels; i++) {
+		int channel = chan_array[i].channel;
 
-		chan_array[i].type = rzg2l_adc_channels[channel].type;
-		chan_array[i].indexed = 1;
-		chan_array[i].channel = channel;
-		chan_array[i].info_mask_separate = BIT(IIO_CHAN_INFO_RAW);
 		chan_array[i].datasheet_name = rzg2l_adc_channels[channel].name;
-		i++;
+		chan_array[i].type = rzg2l_adc_channels[channel].type;
 	}
 
 	data->num_channels = num_channels;

@@ -626,3 +621,4 @@ module_platform_driver(rzg2l_adc_driver);
 MODULE_AUTHOR("Lad Prabhakar <[email protected]>");
 MODULE_DESCRIPTION("Renesas RZ/G2L ADC driver");
 MODULE_LICENSE("GPL v2");
+MODULE_IMPORT_NS("IIO_DRIVER");

2.48.1

The function name changed.

The new devm_iio_adc_device_alloc_chaninfo() -helper is intended to help drivers avoid open-coding the for_each_node -loop for getting the channel IDs. The helper provides standard way to detect the ADC channel nodes (by the node name), and a standard way to convert the "reg" -properties to channel identification numbers, used in the struct iio_chan_spec. Furthermore, the helper can optionally check the found channel IDs are smaller than given maximum. This is useful for callers which later use the IDs for example for indexing a channel data array.

The original driver treated all found child nodes as channel nodes. The new helper requires channel nodes to be named channel[@N]. This should help avoid problems with devices which may contain also other but ADC child nodes. Quick grep from arch/* with the sun20i-gpadc's compatible string didn't reveal any in-tree .dts with channel nodes named otherwise. Also, same grep shows all the in-tree .dts seem to have channel IDs between 0..num of channels.

Use the new helper.

---
Revision history:
v5 => v6:
- Commit message typofix
v4 => v5:
- Drop the diff-channel stuff from the commit message
v3 => v4:
- Adapt to 'drop diff-channel support' changes to ADC-helpers
- select ADC helpers in the Kconfig
v2 => v3:
- New patch

I picked the sun20i-gpadc in this series because it has a straightforward approach for populating the struct iio_chan_spec. Everything else except the .channel can use 'template'-data.

This makes the sun20i-gpadc well suited to be an example user of this new helper. I hope this patch helps to evaluate whether these helpers are worth the hassle.

The change is compile tested only!! Testing before applying is highly appreciated (as always!). Also, even though I tried to audit the dts files for the reg-properties in the channel nodes, use of references didn't make it easy. I can't guarantee I didn't miss anything.

---
 drivers/iio/adc/Kconfig            |  1 +
 drivers/iio/adc/sun20i-gpadc-iio.c | 38 ++++++++++++------------------
 2 files changed, 16 insertions(+), 23 deletions(-)

index e4933de0c366..0993008a1586 100644
@@ -1357,6 +1357,7 @@ config SUN4I_GPADC
 config SUN20I_GPADC
 	tristate "Allwinner D1/T113s/T507/R329 and similar GPADCs driver"
 	depends on ARCH_SUNXI || COMPILE_TEST
+	select IIO_ADC_HELPER
 	help
 	  Say yes here to build support for Allwinner (D1, T113, T507 and R329)
 	  SoCs GPADC. This ADC provides up to 16 channels.

index 136b8d9c294f..bf1db2a3de9b 100644
@@ -15,6 +15,7 @@
 #include <linux/property.h>
 #include <linux/reset.h>
 
+#include <linux/iio/adc-helpers.h>
 #include <linux/iio/iio.h>
 
 #define SUN20I_GPADC_DRIVER_NAME	"sun20i-gpadc"

@@ -149,37 +150,27 @@ static void sun20i_gpadc_reset_assert(void *data)
 	reset_control_assert(rst);
 }
 
+static const struct iio_chan_spec sun20i_gpadc_chan_template = {
+	.type = IIO_VOLTAGE,
+	.indexed = 1,
+	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
+	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),
+};
+
 static int sun20i_gpadc_alloc_channels(struct iio_dev *indio_dev,
 				       struct device *dev)
 {
-	unsigned int channel;
-	int num_channels, i, ret;
+	int num_channels;
 	struct iio_chan_spec *channels;
 
-	num_channels = device_get_child_node_count(dev);
+	num_channels = devm_iio_adc_device_alloc_chaninfo_se(dev,
+				&sun20i_gpadc_chan_template, -1, &channels);
+	if (num_channels < 0)
+		return num_channels;
+
 	if (num_channels == 0)
 		return dev_err_probe(dev, -ENODEV, "no channel children\n");
 
-	channels = devm_kcalloc(dev, num_channels, sizeof(*channels),
-				GFP_KERNEL);
-	if (!channels)
-		return -ENOMEM;
-
-	i = 0;
-	device_for_each_child_node_scoped(dev, node) {
-		ret = fwnode_property_read_u32(node, "reg", &channel);
-		if (ret)
-			return dev_err_probe(dev, ret, "invalid channel number\n");
-
-		channels[i].type = IIO_VOLTAGE;
-		channels[i].indexed = 1;
-		channels[i].channel = channel;
-		channels[i].info_mask_separate = BIT(IIO_CHAN_INFO_RAW);
-		channels[i].info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE);
-
-		i++;
-	}
-
 	indio_dev->channels = channels;
 	indio_dev->num_channels = num_channels;
 

@@ -271,3 +262,4 @@ module_platform_driver(sun20i_gpadc_driver);
 MODULE_DESCRIPTION("ADC driver for sunxi platforms");
 MODULE_AUTHOR("Maksim Kiselev <[email protected]>");
 MODULE_LICENSE("GPL");
+MODULE_IMPORT_NS("IIO_DRIVER");

2.48.1

here as well. I'd have just fixed these up if applying but seeing as you seem to be heading for a v7, good to tidy these up in that!

The ROHM BD79124 is a 12-bit, 8-channel, SAR ADC. The ADC supports an automatic measurement mode, with an alarm interrupt for out-of-window measurements. The window is configurable for each channel.

The I2C protocol for manual start of the measurement and data reading is somewhat peculiar. It requires the master to do clock stretching after sending the I2C slave-address until the slave has captured the data. Needless to say this is not well suopported by the I2C controllers.

Thus the driver does not support the BD79124's manual measurement mode but implements the measurements using automatic measurement mode relying on the BD79124's ability of storing latest measurements into register.

The driver does also support configuring the threshold events for detecting the out-of-window events.

The BD79124 keeps asserting IRQ for as long as the measured voltage is out of the configured window. Thus the driver masks the received event for a fixed duration (1 second) when an event is handled. This prevents the user-space from choking on the events

The ADC input pins can be also configured as general purpose outputs. Those pins which don't have corresponding ADC channel node in the device-tree will be controllable as GPO.

---
Revision history:
v5 => v6:
- Styling as suggested by Jonathan
v4 => v5:
- Drop unused interval defines
- Append unit to interval define and drop a comment
- Drop parenthesis around bitwise negation operation ~
- Use proper block comment style
- Improve the documentation of the re-enabling the events by moving comment explaining early return to the point of the return, and by adding own comment for the reason of locking before calling the re-enabling
- Indenting
- Drop unused struct bd79124_reg_init
- Drop bd79124_init_mux() wrapper and call the regmap_write() directly
v3 => v4:
- Adapt to 'drop diff-channel support' changes to ADC-helpers
- Don't parse fwnode in GPIO valid-mask callback but use pin config cached at probe()
- Drop use of iio_adc_device_channels_by_property()
- Open code the bd79124_reg_init loop (as suggested by Jonathan)
- Use devm variant of mutex_init()
- Styling
v2 => v3:
- Fix uninitialized return value reported by the kernel test robot
- Fix indent
- Adapt to adc-helper changes supporting also single-ended and differential channels
RFC v1 => v2:
- Add event throttling (constant delay of 1 sec)
- rename variable 'd' to 'data'
- Use ADC helpers to detect pins used for ADC
- bd79124 drop MFD and pinmux && handle GPO in this driver
- Drop adc suffix from the IIO file name

drivers/iio/adc/rohm-bd79124.c styling

---
 drivers/iio/adc/Kconfig        |   12 +
 drivers/iio/adc/Makefile       |    1 +
 drivers/iio/adc/rohm-bd79124.c | 1106 ++++++++++++++++++++++++++++++++
 3 files changed, 1119 insertions(+)
 create mode 100644 drivers/iio/adc/rohm-bd79124.c

index 0993008a1586..74d749c0cd8f 100644
@@ -1191,6 +1191,18 @@ config RN5T618_ADC
 	  This driver can also be built as a module. If so, the module
 	  will be called rn5t618-adc.
 
+config ROHM_BD79124
+	tristate "Rohm BD79124 ADC driver"
+	depends on I2C
+	select REGMAP_I2C
+	select IIO_ADC_HELPER
+	help
+	  Say yes here to build support for the ROHM BD79124 ADC. The
+	  ROHM BD79124 is a 12-bit, 8-channel, SAR ADC. The ADC supports
+	  also an automatic measurement mode, with an alarm interrupt for
+	  out-of-window measurements. The window is configurable for each
+	  channel.
+
 config ROCKCHIP_SARADC
 	tristate "Rockchip SARADC driver"
 	depends on ARCH_ROCKCHIP || COMPILE_TEST

index 1c410f483029..3e10af9ec4c4 100644
@@ -109,6 +109,7 @@ obj-$(CONFIG_QCOM_VADC_COMMON) += qcom-vadc-common.o
 obj-$(CONFIG_RCAR_GYRO_ADC) += rcar-gyroadc.o
 obj-$(CONFIG_RICHTEK_RTQ6056) += rtq6056.o
 obj-$(CONFIG_RN5T618_ADC) += rn5t618-adc.o
+obj-$(CONFIG_ROHM_BD79124) += rohm-bd79124.o
 obj-$(CONFIG_ROCKCHIP_SARADC) += rockchip_saradc.o
 obj-$(CONFIG_RZG2L_ADC) += rzg2l_adc.o
 obj-$(CONFIG_SC27XX_ADC) += sc27xx_adc.o

2.48.1

The comment below wins the Monday award for the trivial :)

Add undersigned as a maintainer for the IIO ADC helpers.

---
Revision history:
v2 =>
- No changes
RFC v1 => v2:
- New patch

---
 MAINTAINERS | 7 +++++++
 1 file changed, 7 insertions(+)

index 8e0736dc2ee0..5b96fb864227 100644
@@ -11208,6 +11208,13 @@ L:	[email protected]
 S:	Maintained
 F:	drivers/media/rc/iguanair.c
 
+IIO ADC HELPERS
+M:	Matti Vaittinen <[email protected]>
+L:	[email protected]
+S:	Maintained
+F:	drivers/iio/adc/industrialio-adc.c
+F:	include/linux/iio/adc-helpers.h
+
 IIO BACKEND FRAMEWORK
 M:	Nuno Sa <[email protected]>
 R:	Olivier Moysan <[email protected]>

2.48.1

Add undersigned as a maintainer for the ROHM BD79124 ADC/GPO driver.

---
Revision history:
v2 =>
- No changes
RFC v1 => v2:
- Drop MFD and pinmux drivers

---
 MAINTAINERS | 5 +++++
 1 file changed, 5 insertions(+)

index 5b96fb864227..2e4416b59930 100644
@@ -20547,6 +20547,11 @@ S:	Supported
 F:	drivers/power/supply/bd99954-charger.c
 F:	drivers/power/supply/bd99954-charger.h
 
+ROHM BD79124 ADC / GPO IC
+M:	Matti Vaittinen <[email protected]>
+S:	Supported
+F:	drivers/iio/adc/rohm-bd79124.c
+
 ROHM BH1745 COLOUR SENSOR
 M:	Mudit Sharma <[email protected]>
 L:	[email protected]

2.48.1

We can avoid open-coding the loop construct which counts firmware child nodes with a specific name by using the newly added device_get_child_node_count_named().

The gianfar driver has such open-coded loop. Replace it with the device_get_child_node_count_named().

---
It's fair to tell the pros and cons of this patch.
The simplification is there, but it's not a big one. It comes with a cost of getting the property.h included in this driver which currently uses exclusively the of_* APIs.

NOTE: This patch depends on the patch:
[2/10] "property: Add functions to iterate named child"

Compile-tested only!

---
 drivers/net/ethernet/freescale/gianfar.c | 17 ++++-------------
 1 file changed, 4 insertions(+), 13 deletions(-)

index 435138f4699d..d4ee0fc843be 100644
@@ -97,6 +97,7 @@
 #include <linux/phy_fixed.h>
 #include <linux/of.h>
 #include <linux/of_net.h>
+#include <linux/property.h>
 
 #include "gianfar.h"
 

@@ -571,18 +572,6 @@ static int gfar_parse_group(struct device_node *np,
 	return 0;
 }
 
-static int gfar_of_group_count(struct device_node *np)
-{
-	struct device_node *child;
-	int num = 0;
-
-	for_each_available_child_of_node(np, child)
-		if (of_node_name_eq(child, "queue-group"))
-			num++;
-
-	return num;
-}
-
 /* Reads the controller's registers to determine what interface
  * connects it to the PHY.
  */

@@ -654,8 +643,10 @@ static int gfar_of_init(struct platform_device *ofdev, struct net_device **pdev)
 		num_rx_qs = 1;
 	} else { /* MQ_MG_MODE */
 		/* get the actual number of supported groups */
-		unsigned int num_grps = gfar_of_group_count(np);
+		unsigned int num_grps;
 
+		num_grps = device_get_named_child_node_count(&ofdev->dev,
+							     "queue-group");
 		if (num_grps == 0 || num_grps > MAXGROUPS) {
 			dev_err(&ofdev->dev, "Invalid # of int groups(%d)\n",
 				num_grps);

2.48.1

Slightly simplify code iterating the child nodes with specific names using the new fwnode_for_each_available_named_child_node().

---
Revision history:
v5 => v6:
- New patch

NOTE: This patch depends on the patch:
[2/10] "property: Add functions to iterate named child"

Compile-tested only!

---
 drivers/media/i2c/thp7312.c | 8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

index 8852c56431fe..104754b2ace2 100644
@@ -2067,11 +2067,9 @@ static int thp7312_parse_dt(struct thp7312_device *thp7312)
 		return -EINVAL;
 	}
 
-	fwnode_for_each_available_child_node(sensors, node) {
-		if (fwnode_name_eq(node, "sensor")) {
-			if (!thp7312_sensor_parse_dt(thp7312, node))
-				num_sensors++;
-		}
+	fwnode_for_each_available_named_child_node(sensors, node, "sensor") {
+		if (!thp7312_sensor_parse_dt(thp7312, node))
+			num_sensors++;
 	}
 
 	fwnode_handle_put(sensors);

2.48.1

Hi Matti,

Thank you for the patch.

Regards,

Laurent Pinchart

This probably wants an update. Also, 00/10? There are only 8 that I can see.

Jonathan

That's odd.
There should be 10 in total. And the 4, 5, 9 and 10 was updated.

9/10:
https://lore.kernel.org/all/1c4b9b4ceb1995bce76a0ddef0e04ad0d1d81190.1741610847.git.mazziesaccount@gmail.com/

10/10:
https://lore.kernel.org/all/ab79cf4415d21ff2854fee4f4189fac555c30b7a.1741610847.git.mazziesaccount@gmail.com/

Perhaps it's because of the "net-next" in subject?

Yours,
-- Matti

Nope. My filters broke the series up into different directories.

Thanks,

Jonathan