iio: adc: add support for mcp3911

MCP3911 is a dual channel Analog Front End (AFE) containing two synchronous sampling delta-sigma Analog-to-Digital Converters (ADC).

Co-Developed-by Kent Gustavsson <[email protected]>

Signed-off-by Kent Gustavsson <[email protected]>

Signed-off-by Marcus Folkesson <[email protected]>

Reviewed-by Rob Herring <[email protected]>

---

Notes:
v4:
- remove reference to Documentation/.../interrupts.txt
- add Kent as co-developer
v3:
- add bindings for interrupt
- prefix device-addr with microchip
- drop clock-names
v2:
- drop channel width
- drop external_vref
- replace external-clock with proper clock bindings

 .../devicetree/bindings/iio/adc/mcp3911.txt        | 30 ++++++++++++++++++++++
 1 file changed, 30 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/iio/adc/mcp3911.txt

Documentation/devicetree/bindings/iio/adc/mcp3911.txt new file +30 -0

new file mode 100644
index 000000000000..3071f48fb30b
@@ -0,0 +1,30 @@
+* Microchip MCP3911 Dual channel analog front end (ADC)
+
+Required properties:
+ - compatible: Should be "microchip,mcp3911"
+ - reg: SPI chip select number for the device
+
+Recommended properties:
+ - spi-max-frequency: Definition as per
+	 Documentation/devicetree/bindings/spi/spi-bus.txt.
+	 Max frequency for this chip is 20MHz.
+
+Optional properties:
+ - clocks: Phandle and clock identifier for sampling clock
+ - interrupt-parent: Phandle to the parent interrupt controller
+ - interrupts: IRQ line for the ADC
+ - microchip,device-addr: Device address when multiple MCP3911 chips are present on the
+	same SPI bus. Valid values are 0-3. Defaults to 0.
+ - vref-supply: Phandle to the external reference voltage supply.
+
+Example:
+adc@0 {
+	compatible = "microchip,mcp3911";
+	reg = <0>;
+	interrupt-parent = <&gpio5>;
+	interrupts = <15 IRQ_TYPE_EDGE_RISING>;
+	spi-max-frequency = <20000000>;
+	microchip,device-addr = <0>;
+	vref-supply = <&vref_reg>;
+	clocks = <&xtal>;
+};

MCP3911 is a dual channel Analog Front End (AFE) containing two synchronous sampling delta-sigma Analog-to-Digital Converters (ADC).

Co-Developed-by Kent Gustavsson <[email protected]>

Signed-off-by Kent Gustavsson <[email protected]>

Signed-off-by Marcus Folkesson <[email protected]>

---

Notes:
v4:
- remove defined(CONFIG_OF) and of_match_ptr() macro
- do not check adc->clki as clock api is NULL-aware
- add Kent as co-developer
v3:
- rename adc_clk to clki
- add error handling/cleanup for clock
v2:
- cleanups and bugfixes (thanks Peter Meerwald-Stadler)
- drop hardware gain
- use the presence or lack of regulator to indicate if we go for internal or external voltage reference
- do not store device node in private struct
- drop support to set width in devicetree
- use the presence or lack of clock to indicate if we go for internal or external clock

 drivers/iio/adc/Kconfig   |  10 ++
 drivers/iio/adc/Makefile  |   1 +
 drivers/iio/adc/mcp3911.c | 361 ++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 372 insertions(+)
 create mode 100644 drivers/iio/adc/mcp3911.c

drivers/iio/adc/Kconfig +10 -0

index 15606f237480..f9a41fa96fcc 100644
@@ -501,6 +501,16 @@ config MCP3422
 	  This driver can also be built as a module. If so, the module will be
 	  called mcp3422.
 
+config MCP3911
+	tristate "Microchip Technology MCP3911 driver"
+	depends on SPI
+	help
+	  Say yes here to build support for Microchip Technology's MCP3911
+	  analog to digital converter.
+
+	  This driver can also be built as a module. If so, the module will be
+	  called mcp3911.
+
 config MEDIATEK_MT6577_AUXADC
         tristate "MediaTek AUXADC driver"
         depends on ARCH_MEDIATEK || COMPILE_TEST

drivers/iio/adc/Makefile +1 -0

index 28a9423997f3..3cfebfff7d26 100644
@@ -47,6 +47,7 @@ obj-$(CONFIG_MAX1363) += max1363.o
 obj-$(CONFIG_MAX9611) += max9611.o
 obj-$(CONFIG_MCP320X) += mcp320x.o
 obj-$(CONFIG_MCP3422) += mcp3422.o
+obj-$(CONFIG_MCP3911) += mcp3911.o
 obj-$(CONFIG_MEDIATEK_MT6577_AUXADC) += mt6577_auxadc.o
 obj-$(CONFIG_MEN_Z188_ADC) += men_z188_adc.o
 obj-$(CONFIG_MESON_SARADC) += meson_saradc.o

drivers/iio/adc/mcp3911.c new file +59 -0

new file mode 100644
index 000000000000..540c8fbcce89
@@ -0,0 +1,361 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Driver for Microchip MCP3911, Two-channel Analog Front End
+ *
+ * Copyright (C) 2018 Marcus Folkesson <[email protected]>
+ * Copyright (C) 2018 Kent Gustavsson <[email protected]>
+ */
+#include <linux/clk.h>
+#include <linux/delay.h>
+#include <linux/err.h>
+#include <linux/iio/iio.h>
+#include <linux/module.h>
+#include <linux/regulator/consumer.h>
+#include <linux/spi/spi.h>
+
+#define MCP3911_REG_CHANNEL0		0x00
+#define MCP3911_REG_CHANNEL1		0x03
+#define MCP3911_REG_MOD			0x06
+#define MCP3911_REG_PHASE		0x07
+#define MCP3911_REG_GAIN		0x09
+
+#define MCP3911_REG_STATUSCOM		0x0a
+#define MCP3911_STATUSCOM_CH1_24WIDTH	BIT(4)
+#define MCP3911_STATUSCOM_CH0_24WIDTH	BIT(3)
+#define MCP3911_STATUSCOM_EN_OFFCAL	BIT(2)
+#define MCP3911_STATUSCOM_EN_GAINCAL	BIT(1)
+
+#define MCP3911_REG_CONFIG		0x0c
+#define MCP3911_CONFIG_CLKEXT		BIT(1)
+#define MCP3911_CONFIG_VREFEXT		BIT(2)
+
+#define MCP3911_REG_OFFCAL_CH0		0x0e
+#define MCP3911_REG_GAINCAL_CH0		0x11
+#define MCP3911_REG_OFFCAL_CH1		0x14
+#define MCP3911_REG_GAINCAL_CH1		0x17
+#define MCP3911_REG_VREFCAL		0x1a
+
+#define MCP3911_CHANNEL(x)		(MCP3911_REG_CHANNEL0 + x * 3)
+#define MCP3911_OFFCAL(x)		(MCP3911_REG_OFFCAL_CH0 + x * 6)
+
+/* Internal voltage reference in uV */
+#define MCP3911_INT_VREF_UV		1200000
+
+#define MCP3911_REG_READ(reg, id)	((((reg) << 1) | ((id) << 5) | (1 << 0)) & 0xff)
+#define MCP3911_REG_WRITE(reg, id)	((((reg) << 1) | ((id) << 5) | (0 << 0)) & 0xff)
+
+#define MCP3911_NUM_CHANNELS		2
+
+struct mcp3911 {
+	struct spi_device *spi;
+	struct mutex lock;
+	struct regulator *vref;
+	struct clk *clki;
+	u32 dev_addr;
+};
+
+static int mcp3911_read(struct mcp3911 *adc, u8 reg, u32 *val, u8 len)
+{
+	int ret;

drivers/iio/adc/mcp3911.c new file +85 -0

+	return ret;
+}
+
+static int mcp3911_write(struct mcp3911 *adc, u8 reg, u32 val, u8 len)
+{
+	dev_dbg(&adc->spi->dev, "writing 0x%x to register 0x%x\n", val, reg);
+
+	val <<= (3 - len) * 8;
+	cpu_to_be32s(&val);
+	val |= MCP3911_REG_WRITE(reg, adc->dev_addr);
+
+	return spi_write(adc->spi, &val, len + 1);
+}
+
+static int mcp3911_update(struct mcp3911 *adc, u8 reg, u32 mask,
+		u32 val, u8 len)
+{
+	u32 tmp;
+	int ret;
+
+	ret = mcp3911_read(adc, reg, &tmp, len);
+	if (ret)
+		return ret;
+
+	val &= mask;
+	val |= tmp & ~mask;
+	return mcp3911_write(adc, reg, val, len);
+}
+
+static int mcp3911_read_raw(struct iio_dev *indio_dev,
+			    struct iio_chan_spec const *channel, int *val,
+			    int *val2, long mask)
+{
+	struct mcp3911 *adc = iio_priv(indio_dev);
+	int ret = -EINVAL;
+
+	mutex_lock(&adc->lock);
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW:
+		ret = mcp3911_read(adc,
+				MCP3911_CHANNEL(channel->channel), val, 3);
+		if (ret)
+			goto out;
+
+		ret = IIO_VAL_INT;
+		break;
+
+	case IIO_CHAN_INFO_OFFSET:
+		ret = mcp3911_read(adc,
+				MCP3911_OFFCAL(channel->channel), val, 3);
+		if (ret)
+			goto out;
+
+		ret = IIO_VAL_INT;
+		break;
+
+	case IIO_CHAN_INFO_SCALE:
+		if (adc->vref) {
+			ret = regulator_get_voltage(adc->vref);
+			if (ret < 0) {
+				dev_err(indio_dev->dev.parent,
+					"failed to get vref voltage: %d\n",
+				       ret);
+				goto out;
+			}
+
+			*val = ret / 1000;
+		} else {
+			*val = MCP3911_INT_VREF_UV;
+		}
+
+		*val2 = 24;
+		ret = IIO_VAL_FRACTIONAL_LOG2;
+		break;
+	}
+
+out:
+	mutex_unlock(&adc->lock);
+	return ret;
+}
+
+static int mcp3911_write_raw(struct iio_dev *indio_dev,
+			    struct iio_chan_spec const *channel, int val,
+			    int val2, long mask)
+{

drivers/iio/adc/mcp3911.c new file +197 -0

+
+		/* Write offset */
+		ret = mcp3911_write(adc, MCP3911_OFFCAL(channel->channel), val,
+				3);
+		if (ret)
+			goto out;
+
+		/* Enable offset*/
+		ret = mcp3911_update(adc, MCP3911_REG_STATUSCOM,
+				MCP3911_STATUSCOM_EN_OFFCAL,
+				MCP3911_STATUSCOM_EN_OFFCAL, 2);
+		break;
+	}
+
+out:
+	mutex_unlock(&adc->lock);
+	return ret;
+}
+
+#define MCP3911_CHAN(idx) {					\
+		.type = IIO_VOLTAGE,				\
+		.indexed = 1,					\
+		.channel = idx,					\
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |	\
+			BIT(IIO_CHAN_INFO_OFFSET) |		\
+			BIT(IIO_CHAN_INFO_SCALE),		\
+}
+
+static const struct iio_chan_spec mcp3911_channels[] = {
+	MCP3911_CHAN(0),
+	MCP3911_CHAN(1),
+};
+
+static const struct iio_info mcp3911_info = {
+	.read_raw = mcp3911_read_raw,
+	.write_raw = mcp3911_write_raw,
+};
+
+static int mcp3911_config(struct mcp3911 *adc, struct device_node *of_node)
+{
+	u32 configreg;
+	int ret;
+
+	of_property_read_u32(of_node, "device-addr", &adc->dev_addr);
+	if (adc->dev_addr > 3) {
+		dev_err(&adc->spi->dev,
+				"invalid device address (%i). Must be in range 0-3.\n",
+				adc->dev_addr);
+		return -EINVAL;
+	}
+	dev_dbg(&adc->spi->dev, "use device address %i\n", adc->dev_addr);
+
+	ret = mcp3911_read(adc, MCP3911_REG_CONFIG, &configreg, 2);
+	if (ret)
+		return ret;
+
+	if (adc->vref) {
+		dev_dbg(&adc->spi->dev, "use external voltage reference\n");
+		configreg |= MCP3911_CONFIG_VREFEXT;
+	} else {
+		dev_dbg(&adc->spi->dev, "use internal voltage reference (1.2V)\n");
+		configreg &= ~MCP3911_CONFIG_VREFEXT;
+	}
+
+	if (adc->clki) {
+		dev_dbg(&adc->spi->dev, "use external clock as clocksource\n");
+		configreg |= MCP3911_CONFIG_CLKEXT;
+	} else {
+		dev_dbg(&adc->spi->dev, "use crystal oscillator as clocksource\n");
+		configreg &= ~MCP3911_CONFIG_CLKEXT;
+	}
+
+	return  mcp3911_write(adc, MCP3911_REG_CONFIG, configreg, 2);
+}
+
+static int mcp3911_probe(struct spi_device *spi)
+{
+	struct iio_dev *indio_dev;
+	struct mcp3911 *adc;
+	int ret;
+
+	indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*adc));
+	if (!indio_dev)
+		return -ENOMEM;
+
+	adc = iio_priv(indio_dev);
+	adc->spi = spi;
+
+	adc->vref = devm_regulator_get_optional(&adc->spi->dev, "vref");
+	if (IS_ERR(adc->vref)) {
+		if (PTR_ERR(adc->vref) == -ENODEV) {
+			adc->vref = NULL;
+		} else {
+			dev_err(&adc->spi->dev,
+					"failed to get regulator (%ld)\n",
+					PTR_ERR(adc->vref));
+			return PTR_ERR(adc->vref);
+		}
+
+	} else {
+		ret = regulator_enable(adc->vref);
+		if (ret)
+			return ret;
+	}
+
+	adc->clki = devm_clk_get(&adc->spi->dev, NULL);
+	if (IS_ERR(adc->clki)) {
+		if (PTR_ERR(adc->clki) == -ENOENT) {
+			adc->clki = NULL;
+		} else {
+			dev_err(&adc->spi->dev,
+					"failed to get adc clk (%ld)\n",
+					PTR_ERR(adc->clki));
+			ret = PTR_ERR(adc->clki);
+			goto reg_disable;
+		}
+	} else {
+		ret = clk_prepare_enable(adc->clki);
+		if (ret < 0) {
+			dev_err(&adc->spi->dev,
+				"Failed to enable clki: %d\n", ret);
+			goto reg_disable;
+		}
+	}
+
+	ret = mcp3911_config(adc, spi->dev.of_node);
+	if (ret)
+		goto clk_disable;
+
+	indio_dev->dev.parent = &spi->dev;
+	indio_dev->dev.of_node = spi->dev.of_node;
+	indio_dev->name = spi_get_device_id(spi)->name;
+	indio_dev->modes = INDIO_DIRECT_MODE;
+	indio_dev->info = &mcp3911_info;
+	spi_set_drvdata(spi, indio_dev);
+
+	indio_dev->channels = mcp3911_channels;
+	indio_dev->num_channels = ARRAY_SIZE(mcp3911_channels);
+
+	mutex_init(&adc->lock);
+
+	ret = iio_device_register(indio_dev);
+	if (ret)
+		goto clk_disable;
+
+	return ret;
+
+clk_disable:
+	clk_disable_unprepare(adc->clki);
+reg_disable:
+	if (adc->vref)
+		regulator_disable(adc->vref);
+
+	return ret;
+}
+
+static int mcp3911_remove(struct spi_device *spi)
+{
+	struct iio_dev *indio_dev = spi_get_drvdata(spi);
+	struct mcp3911 *adc = iio_priv(indio_dev);
+
+	iio_device_unregister(indio_dev);
+
+	clk_disable_unprepare(adc->clki);
+	if (adc->vref)
+		regulator_disable(adc->vref);
+
+	return 0;
+}
+
+static const struct of_device_id mcp3911_dt_ids[] = {
+	{ .compatible = "microchip,mcp3911" },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, mcp3911_dt_ids);
+
+static const struct spi_device_id mcp3911_id[] = {
+	{ "mcp3911", 0 },
+	{ }
+};
+MODULE_DEVICE_TABLE(spi, mcp3911_id);
+
+static struct spi_driver mcp3911_driver = {
+	.driver = {
+		.name = "mcp3911",
+		.of_match_table = mcp3911_dt_ids,
+	},
+	.probe = mcp3911_probe,
+	.remove = mcp3911_remove,
+	.id_table = mcp3911_id,
+};
+module_spi_driver(mcp3911_driver);
+
+MODULE_AUTHOR("Marcus Folkesson <[email protected]>");
+MODULE_AUTHOR("Kent Gustavsson <[email protected]>");
+MODULE_DESCRIPTION("Microchip Technology MCP3911");
+MODULE_LICENSE("GPL v2");

Quoted 4 lines · On Wed, 8 Aug 2018 10:09:15 +0200 Marcus Folkesson…

MCP3911 is a dual channel Analog Front End (AFE) containing two synchronous sampling delta-sigma Analog-to-Digital Converters (ADC).

Co-Developed-by Kent Gustavsson <[email protected]>

checkpatch points out..
Co-developed-by is the 'official' form of the tag. I'll fixup. (first time I've seen one of these ;)

Quoted 3 lines

Signed-off-by Kent Gustavsson <[email protected]>

Signed-off-by Marcus Folkesson <[email protected]>

Applied to the togreg branch of iio.git and pushed out as testing for the autobuilders to play with it.

A few really trivial comments inline. Also some slightly odd alignment I'll fix up that I haven't noted, but not every parameter second line lines up with the opening brackets correctly.

Jonathan

Quoted 122 lines

---

Notes:
v4:
- remove defined(CONFIG_OF) and of_match_ptr() macro
- do not check adc->clki as clock api is NULL-aware
- add Kent as co-developer
v3:
- rename adc_clk to clki
- add error handling/cleanup for clock
v2:
- cleanups and bugfixes (thanks Peter Meerwald-Stadler)
- drop hardware gain
- use the presence or lack of regulator to indicate if we go for internal or external voltage reference
- do not store device node in private struct
- drop support to set width in devicetree
- use the presence or lack of clock to indicate if we go for internal or external clock

 drivers/iio/adc/Kconfig   |  10 ++
 drivers/iio/adc/Makefile  |   1 +
 drivers/iio/adc/mcp3911.c | 361 ++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 372 insertions(+)
 create mode 100644 drivers/iio/adc/mcp3911.c

drivers/iio/adc/Kconfig +10 -0

index 15606f237480..f9a41fa96fcc 100644
@@ -501,6 +501,16 @@ config MCP3422
 	  This driver can also be built as a module. If so, the module will be
 	  called mcp3422.
 
+config MCP3911
+	tristate "Microchip Technology MCP3911 driver"
+	depends on SPI
+	help
+	  Say yes here to build support for Microchip Technology's MCP3911
+	  analog to digital converter.
+
+	  This driver can also be built as a module. If so, the module will be
+	  called mcp3911.
+
 config MEDIATEK_MT6577_AUXADC
         tristate "MediaTek AUXADC driver"
         depends on ARCH_MEDIATEK || COMPILE_TEST

drivers/iio/adc/Makefile +1 -0

index 28a9423997f3..3cfebfff7d26 100644
@@ -47,6 +47,7 @@ obj-$(CONFIG_MAX1363) += max1363.o
 obj-$(CONFIG_MAX9611) += max9611.o
 obj-$(CONFIG_MCP320X) += mcp320x.o
 obj-$(CONFIG_MCP3422) += mcp3422.o
+obj-$(CONFIG_MCP3911) += mcp3911.o
 obj-$(CONFIG_MEDIATEK_MT6577_AUXADC) += mt6577_auxadc.o
 obj-$(CONFIG_MEN_Z188_ADC) += men_z188_adc.o
 obj-$(CONFIG_MESON_SARADC) += meson_saradc.o

drivers/iio/adc/mcp3911.c new file +59 -0

new file mode 100644
index 000000000000..540c8fbcce89
@@ -0,0 +1,361 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Driver for Microchip MCP3911, Two-channel Analog Front End
+ *
+ * Copyright (C) 2018 Marcus Folkesson <[email protected]>
+ * Copyright (C) 2018 Kent Gustavsson <[email protected]>
+ */
+#include <linux/clk.h>
+#include <linux/delay.h>
+#include <linux/err.h>
+#include <linux/iio/iio.h>
+#include <linux/module.h>
+#include <linux/regulator/consumer.h>
+#include <linux/spi/spi.h>
+
+#define MCP3911_REG_CHANNEL0		0x00
+#define MCP3911_REG_CHANNEL1		0x03
+#define MCP3911_REG_MOD			0x06
+#define MCP3911_REG_PHASE		0x07
+#define MCP3911_REG_GAIN		0x09
+
+#define MCP3911_REG_STATUSCOM		0x0a
+#define MCP3911_STATUSCOM_CH1_24WIDTH	BIT(4)
+#define MCP3911_STATUSCOM_CH0_24WIDTH	BIT(3)
+#define MCP3911_STATUSCOM_EN_OFFCAL	BIT(2)
+#define MCP3911_STATUSCOM_EN_GAINCAL	BIT(1)
+
+#define MCP3911_REG_CONFIG		0x0c
+#define MCP3911_CONFIG_CLKEXT		BIT(1)
+#define MCP3911_CONFIG_VREFEXT		BIT(2)
+
+#define MCP3911_REG_OFFCAL_CH0		0x0e
+#define MCP3911_REG_GAINCAL_CH0		0x11
+#define MCP3911_REG_OFFCAL_CH1		0x14
+#define MCP3911_REG_GAINCAL_CH1		0x17
+#define MCP3911_REG_VREFCAL		0x1a
+
+#define MCP3911_CHANNEL(x)		(MCP3911_REG_CHANNEL0 + x * 3)
+#define MCP3911_OFFCAL(x)		(MCP3911_REG_OFFCAL_CH0 + x * 6)
+
+/* Internal voltage reference in uV */
+#define MCP3911_INT_VREF_UV		1200000
+
+#define MCP3911_REG_READ(reg, id)	((((reg) << 1) | ((id) << 5) | (1 << 0)) & 0xff)
+#define MCP3911_REG_WRITE(reg, id)	((((reg) << 1) | ((id) << 5) | (0 << 0)) & 0xff)
+
+#define MCP3911_NUM_CHANNELS		2
+
+struct mcp3911 {
+	struct spi_device *spi;
+	struct mutex lock;
+	struct regulator *vref;
+	struct clk *clki;
+	u32 dev_addr;
+};
+
+static int mcp3911_read(struct mcp3911 *adc, u8 reg, u32 *val, u8 len)
+{
+	int ret;

drivers/iio/adc/mcp3911.c line 69

Quoted 10 lines

drivers/iio/adc/mcp3911.c new file +10 -0

+
+	reg = MCP3911_REG_READ(reg, adc->dev_addr);
+	ret = spi_write_then_read(adc->spi, &reg, 1, val, len);
+	if (ret < 0)
+		return ret;
+
+	be32_to_cpus(val);
+	*val >>= ((4 - len) * 8);
+	dev_dbg(&adc->spi->dev, "reading 0x%x from register 0x%x\n", *val,
+			reg>>1);

Spaces around that >> preferred - I'll add them.

Quoted 85 lines

drivers/iio/adc/mcp3911.c new file +85 -0

+	return ret;
+}
+
+static int mcp3911_write(struct mcp3911 *adc, u8 reg, u32 val, u8 len)
+{
+	dev_dbg(&adc->spi->dev, "writing 0x%x to register 0x%x\n", val, reg);
+
+	val <<= (3 - len) * 8;
+	cpu_to_be32s(&val);
+	val |= MCP3911_REG_WRITE(reg, adc->dev_addr);
+
+	return spi_write(adc->spi, &val, len + 1);
+}
+
+static int mcp3911_update(struct mcp3911 *adc, u8 reg, u32 mask,
+		u32 val, u8 len)
+{
+	u32 tmp;
+	int ret;
+
+	ret = mcp3911_read(adc, reg, &tmp, len);
+	if (ret)
+		return ret;
+
+	val &= mask;
+	val |= tmp & ~mask;
+	return mcp3911_write(adc, reg, val, len);
+}
+
+static int mcp3911_read_raw(struct iio_dev *indio_dev,
+			    struct iio_chan_spec const *channel, int *val,
+			    int *val2, long mask)
+{
+	struct mcp3911 *adc = iio_priv(indio_dev);
+	int ret = -EINVAL;
+
+	mutex_lock(&adc->lock);
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW:
+		ret = mcp3911_read(adc,
+				MCP3911_CHANNEL(channel->channel), val, 3);
+		if (ret)
+			goto out;
+
+		ret = IIO_VAL_INT;
+		break;
+
+	case IIO_CHAN_INFO_OFFSET:
+		ret = mcp3911_read(adc,
+				MCP3911_OFFCAL(channel->channel), val, 3);
+		if (ret)
+			goto out;
+
+		ret = IIO_VAL_INT;
+		break;
+
+	case IIO_CHAN_INFO_SCALE:
+		if (adc->vref) {
+			ret = regulator_get_voltage(adc->vref);
+			if (ret < 0) {
+				dev_err(indio_dev->dev.parent,
+					"failed to get vref voltage: %d\n",
+				       ret);
+				goto out;
+			}
+
+			*val = ret / 1000;
+		} else {
+			*val = MCP3911_INT_VREF_UV;
+		}
+
+		*val2 = 24;
+		ret = IIO_VAL_FRACTIONAL_LOG2;
+		break;
+	}
+
+out:
+	mutex_unlock(&adc->lock);
+	return ret;
+}
+
+static int mcp3911_write_raw(struct iio_dev *indio_dev,
+			    struct iio_chan_spec const *channel, int val,
+			    int val2, long mask)
+{

drivers/iio/adc/mcp3911.c line 164

Quoted 10 lines

drivers/iio/adc/mcp3911.c new file +10 -0

+	struct mcp3911 *adc = iio_priv(indio_dev);
+	int ret = -EINVAL;
+
+	mutex_lock(&adc->lock);
+	switch (mask) {
+	case IIO_CHAN_INFO_OFFSET:
+		if (val2 != 0) {
+			ret = -EINVAL;
+			goto out;
+		}

Nitpick that I don't care about enough to delay on this. Could have moved the lock into the case statement then done the check outside the lock which would have been slightly nicer.

Quoted 189 lines

drivers/iio/adc/mcp3911.c new file +189 -0

+
+		/* Write offset */
+		ret = mcp3911_write(adc, MCP3911_OFFCAL(channel->channel), val,
+				3);
+		if (ret)
+			goto out;
+
+		/* Enable offset*/
+		ret = mcp3911_update(adc, MCP3911_REG_STATUSCOM,
+				MCP3911_STATUSCOM_EN_OFFCAL,
+				MCP3911_STATUSCOM_EN_OFFCAL, 2);
+		break;
+	}
+
+out:
+	mutex_unlock(&adc->lock);
+	return ret;
+}
+
+#define MCP3911_CHAN(idx) {					\
+		.type = IIO_VOLTAGE,				\
+		.indexed = 1,					\
+		.channel = idx,					\
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |	\
+			BIT(IIO_CHAN_INFO_OFFSET) |		\
+			BIT(IIO_CHAN_INFO_SCALE),		\
+}
+
+static const struct iio_chan_spec mcp3911_channels[] = {
+	MCP3911_CHAN(0),
+	MCP3911_CHAN(1),
+};
+
+static const struct iio_info mcp3911_info = {
+	.read_raw = mcp3911_read_raw,
+	.write_raw = mcp3911_write_raw,
+};
+
+static int mcp3911_config(struct mcp3911 *adc, struct device_node *of_node)
+{
+	u32 configreg;
+	int ret;
+
+	of_property_read_u32(of_node, "device-addr", &adc->dev_addr);
+	if (adc->dev_addr > 3) {
+		dev_err(&adc->spi->dev,
+				"invalid device address (%i). Must be in range 0-3.\n",
+				adc->dev_addr);
+		return -EINVAL;
+	}
+	dev_dbg(&adc->spi->dev, "use device address %i\n", adc->dev_addr);
+
+	ret = mcp3911_read(adc, MCP3911_REG_CONFIG, &configreg, 2);
+	if (ret)
+		return ret;
+
+	if (adc->vref) {
+		dev_dbg(&adc->spi->dev, "use external voltage reference\n");
+		configreg |= MCP3911_CONFIG_VREFEXT;
+	} else {
+		dev_dbg(&adc->spi->dev, "use internal voltage reference (1.2V)\n");
+		configreg &= ~MCP3911_CONFIG_VREFEXT;
+	}
+
+	if (adc->clki) {
+		dev_dbg(&adc->spi->dev, "use external clock as clocksource\n");
+		configreg |= MCP3911_CONFIG_CLKEXT;
+	} else {
+		dev_dbg(&adc->spi->dev, "use crystal oscillator as clocksource\n");
+		configreg &= ~MCP3911_CONFIG_CLKEXT;
+	}
+
+	return  mcp3911_write(adc, MCP3911_REG_CONFIG, configreg, 2);
+}
+
+static int mcp3911_probe(struct spi_device *spi)
+{
+	struct iio_dev *indio_dev;
+	struct mcp3911 *adc;
+	int ret;
+
+	indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*adc));
+	if (!indio_dev)
+		return -ENOMEM;
+
+	adc = iio_priv(indio_dev);
+	adc->spi = spi;
+
+	adc->vref = devm_regulator_get_optional(&adc->spi->dev, "vref");
+	if (IS_ERR(adc->vref)) {
+		if (PTR_ERR(adc->vref) == -ENODEV) {
+			adc->vref = NULL;
+		} else {
+			dev_err(&adc->spi->dev,
+					"failed to get regulator (%ld)\n",
+					PTR_ERR(adc->vref));
+			return PTR_ERR(adc->vref);
+		}
+
+	} else {
+		ret = regulator_enable(adc->vref);
+		if (ret)
+			return ret;
+	}
+
+	adc->clki = devm_clk_get(&adc->spi->dev, NULL);
+	if (IS_ERR(adc->clki)) {
+		if (PTR_ERR(adc->clki) == -ENOENT) {
+			adc->clki = NULL;
+		} else {
+			dev_err(&adc->spi->dev,
+					"failed to get adc clk (%ld)\n",
+					PTR_ERR(adc->clki));
+			ret = PTR_ERR(adc->clki);
+			goto reg_disable;
+		}
+	} else {
+		ret = clk_prepare_enable(adc->clki);
+		if (ret < 0) {
+			dev_err(&adc->spi->dev,
+				"Failed to enable clki: %d\n", ret);
+			goto reg_disable;
+		}
+	}
+
+	ret = mcp3911_config(adc, spi->dev.of_node);
+	if (ret)
+		goto clk_disable;
+
+	indio_dev->dev.parent = &spi->dev;
+	indio_dev->dev.of_node = spi->dev.of_node;
+	indio_dev->name = spi_get_device_id(spi)->name;
+	indio_dev->modes = INDIO_DIRECT_MODE;
+	indio_dev->info = &mcp3911_info;
+	spi_set_drvdata(spi, indio_dev);
+
+	indio_dev->channels = mcp3911_channels;
+	indio_dev->num_channels = ARRAY_SIZE(mcp3911_channels);
+
+	mutex_init(&adc->lock);
+
+	ret = iio_device_register(indio_dev);
+	if (ret)
+		goto clk_disable;
+
+	return ret;
+
+clk_disable:
+	clk_disable_unprepare(adc->clki);
+reg_disable:
+	if (adc->vref)
+		regulator_disable(adc->vref);
+
+	return ret;
+}
+
+static int mcp3911_remove(struct spi_device *spi)
+{
+	struct iio_dev *indio_dev = spi_get_drvdata(spi);
+	struct mcp3911 *adc = iio_priv(indio_dev);
+
+	iio_device_unregister(indio_dev);
+
+	clk_disable_unprepare(adc->clki);
+	if (adc->vref)
+		regulator_disable(adc->vref);
+
+	return 0;
+}
+
+static const struct of_device_id mcp3911_dt_ids[] = {
+	{ .compatible = "microchip,mcp3911" },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, mcp3911_dt_ids);
+
+static const struct spi_device_id mcp3911_id[] = {
+	{ "mcp3911", 0 },
+	{ }
+};
+MODULE_DEVICE_TABLE(spi, mcp3911_id);
+
+static struct spi_driver mcp3911_driver = {
+	.driver = {
+		.name = "mcp3911",
+		.of_match_table = mcp3911_dt_ids,
+	},
+	.probe = mcp3911_probe,
+	.remove = mcp3911_remove,

drivers/iio/adc/mcp3911.c line 361

Quoted 8 lines

drivers/iio/adc/mcp3911.c new file +8 -0

+	.id_table = mcp3911_id,
+};
+module_spi_driver(mcp3911_driver);
+
+MODULE_AUTHOR("Marcus Folkesson <[email protected]>");
+MODULE_AUTHOR("Kent Gustavsson <[email protected]>");
+MODULE_DESCRIPTION("Microchip Technology MCP3911");
+MODULE_LICENSE("GPL v2");

Quoted 6 lines · Jonathan Cameron

Quoted 3 lines · On Wed, 8 Aug 2018 10:09:15 +0200 Marcus Folkesson…

MCP3911 is a dual channel Analog Front End (AFE) containing two synchronous sampling delta-sigma Analog-to-Digital Converters (ADC).

Quoted 4 lines

Quoted 1 line

Co-Developed-by Kent Gustavsson <[email protected]>

checkpatch points out..
Co-developed-by is the 'official' form of the tag. I'll fixup. (first time I've seen one of these ;)

Yep, I also noticed that checkpatch is not Co-developed-by-aware yet. I tried to fix it, but Perl is just such a terrible language that I considered it impossible.

Quoted 10 lines

Quoted 4 lines

Signed-off-by Kent Gustavsson <[email protected]>

Signed-off-by Marcus Folkesson <[email protected]>

Applied to the togreg branch of iio.git and pushed out as testing for the autobuilders to play with it.

A few really trivial comments inline. Also some slightly odd alignment I'll fix up that I haven't noted, but not every parameter second line lines up with the opening brackets correctly.

Thank you.

Quoted 425 lines

Jonathan

Quoted 122 lines

---

Notes:
v4:
- remove defined(CONFIG_OF) and of_match_ptr() macro
- do not check adc->clki as clock api is NULL-aware
- add Kent as co-developer
v3:
- rename adc_clk to clki
- add error handling/cleanup for clock
v2:
- cleanups and bugfixes (thanks Peter Meerwald-Stadler)
- drop hardware gain
- use the presence or lack of regulator to indicate if we go for internal or external voltage reference
- do not store device node in private struct
- drop support to set width in devicetree
- use the presence or lack of clock to indicate if we go for internal or external clock

 drivers/iio/adc/Kconfig   |  10 ++
 drivers/iio/adc/Makefile  |   1 +
 drivers/iio/adc/mcp3911.c | 361 ++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 372 insertions(+)
 create mode 100644 drivers/iio/adc/mcp3911.c

drivers/iio/adc/Kconfig +10 -0

index 15606f237480..f9a41fa96fcc 100644
@@ -501,6 +501,16 @@ config MCP3422
 	  This driver can also be built as a module. If so, the module will be
 	  called mcp3422.
 
+config MCP3911
+	tristate "Microchip Technology MCP3911 driver"
+	depends on SPI
+	help
+	  Say yes here to build support for Microchip Technology's MCP3911
+	  analog to digital converter.
+
+	  This driver can also be built as a module. If so, the module will be
+	  called mcp3911.
+
 config MEDIATEK_MT6577_AUXADC
         tristate "MediaTek AUXADC driver"
         depends on ARCH_MEDIATEK || COMPILE_TEST

drivers/iio/adc/Makefile +1 -0

index 28a9423997f3..3cfebfff7d26 100644
@@ -47,6 +47,7 @@ obj-$(CONFIG_MAX1363) += max1363.o
 obj-$(CONFIG_MAX9611) += max9611.o
 obj-$(CONFIG_MCP320X) += mcp320x.o
 obj-$(CONFIG_MCP3422) += mcp3422.o
+obj-$(CONFIG_MCP3911) += mcp3911.o
 obj-$(CONFIG_MEDIATEK_MT6577_AUXADC) += mt6577_auxadc.o
 obj-$(CONFIG_MEN_Z188_ADC) += men_z188_adc.o
 obj-$(CONFIG_MESON_SARADC) += meson_saradc.o

drivers/iio/adc/mcp3911.c new file +59 -0

new file mode 100644
index 000000000000..540c8fbcce89
@@ -0,0 +1,361 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Driver for Microchip MCP3911, Two-channel Analog Front End
+ *
+ * Copyright (C) 2018 Marcus Folkesson <[email protected]>
+ * Copyright (C) 2018 Kent Gustavsson <[email protected]>
+ */
+#include <linux/clk.h>
+#include <linux/delay.h>
+#include <linux/err.h>
+#include <linux/iio/iio.h>
+#include <linux/module.h>
+#include <linux/regulator/consumer.h>
+#include <linux/spi/spi.h>
+
+#define MCP3911_REG_CHANNEL0		0x00
+#define MCP3911_REG_CHANNEL1		0x03
+#define MCP3911_REG_MOD			0x06
+#define MCP3911_REG_PHASE		0x07
+#define MCP3911_REG_GAIN		0x09
+
+#define MCP3911_REG_STATUSCOM		0x0a
+#define MCP3911_STATUSCOM_CH1_24WIDTH	BIT(4)
+#define MCP3911_STATUSCOM_CH0_24WIDTH	BIT(3)
+#define MCP3911_STATUSCOM_EN_OFFCAL	BIT(2)
+#define MCP3911_STATUSCOM_EN_GAINCAL	BIT(1)
+
+#define MCP3911_REG_CONFIG		0x0c
+#define MCP3911_CONFIG_CLKEXT		BIT(1)
+#define MCP3911_CONFIG_VREFEXT		BIT(2)
+
+#define MCP3911_REG_OFFCAL_CH0		0x0e
+#define MCP3911_REG_GAINCAL_CH0		0x11
+#define MCP3911_REG_OFFCAL_CH1		0x14
+#define MCP3911_REG_GAINCAL_CH1		0x17
+#define MCP3911_REG_VREFCAL		0x1a
+
+#define MCP3911_CHANNEL(x)		(MCP3911_REG_CHANNEL0 + x * 3)
+#define MCP3911_OFFCAL(x)		(MCP3911_REG_OFFCAL_CH0 + x * 6)
+
+/* Internal voltage reference in uV */
+#define MCP3911_INT_VREF_UV		1200000
+
+#define MCP3911_REG_READ(reg, id)	((((reg) << 1) | ((id) << 5) | (1 << 0)) & 0xff)
+#define MCP3911_REG_WRITE(reg, id)	((((reg) << 1) | ((id) << 5) | (0 << 0)) & 0xff)
+
+#define MCP3911_NUM_CHANNELS		2
+
+struct mcp3911 {
+	struct spi_device *spi;
+	struct mutex lock;
+	struct regulator *vref;
+	struct clk *clki;
+	u32 dev_addr;
+};
+
+static int mcp3911_read(struct mcp3911 *adc, u8 reg, u32 *val, u8 len)
+{
+	int ret;

drivers/iio/adc/mcp3911.c line 69

Quoted 10 lines

drivers/iio/adc/mcp3911.c new file +10 -0

+
+	reg = MCP3911_REG_READ(reg, adc->dev_addr);
+	ret = spi_write_then_read(adc->spi, &reg, 1, val, len);
+	if (ret < 0)
+		return ret;
+
+	be32_to_cpus(val);
+	*val >>= ((4 - len) * 8);
+	dev_dbg(&adc->spi->dev, "reading 0x%x from register 0x%x\n", *val,
+			reg>>1);  

Spaces around that >> preferred - I'll add them.

Quoted 85 lines

drivers/iio/adc/mcp3911.c new file +85 -0

+	return ret;
+}
+
+static int mcp3911_write(struct mcp3911 *adc, u8 reg, u32 val, u8 len)
+{
+	dev_dbg(&adc->spi->dev, "writing 0x%x to register 0x%x\n", val, reg);
+
+	val <<= (3 - len) * 8;
+	cpu_to_be32s(&val);
+	val |= MCP3911_REG_WRITE(reg, adc->dev_addr);
+
+	return spi_write(adc->spi, &val, len + 1);
+}
+
+static int mcp3911_update(struct mcp3911 *adc, u8 reg, u32 mask,
+		u32 val, u8 len)
+{
+	u32 tmp;
+	int ret;
+
+	ret = mcp3911_read(adc, reg, &tmp, len);
+	if (ret)
+		return ret;
+
+	val &= mask;
+	val |= tmp & ~mask;
+	return mcp3911_write(adc, reg, val, len);
+}
+
+static int mcp3911_read_raw(struct iio_dev *indio_dev,
+			    struct iio_chan_spec const *channel, int *val,
+			    int *val2, long mask)
+{
+	struct mcp3911 *adc = iio_priv(indio_dev);
+	int ret = -EINVAL;
+
+	mutex_lock(&adc->lock);
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW:
+		ret = mcp3911_read(adc,
+				MCP3911_CHANNEL(channel->channel), val, 3);
+		if (ret)
+			goto out;
+
+		ret = IIO_VAL_INT;
+		break;
+
+	case IIO_CHAN_INFO_OFFSET:
+		ret = mcp3911_read(adc,
+				MCP3911_OFFCAL(channel->channel), val, 3);
+		if (ret)
+			goto out;
+
+		ret = IIO_VAL_INT;
+		break;
+
+	case IIO_CHAN_INFO_SCALE:
+		if (adc->vref) {
+			ret = regulator_get_voltage(adc->vref);
+			if (ret < 0) {
+				dev_err(indio_dev->dev.parent,
+					"failed to get vref voltage: %d\n",
+				       ret);
+				goto out;
+			}
+
+			*val = ret / 1000;
+		} else {
+			*val = MCP3911_INT_VREF_UV;
+		}
+
+		*val2 = 24;
+		ret = IIO_VAL_FRACTIONAL_LOG2;
+		break;
+	}
+
+out:
+	mutex_unlock(&adc->lock);
+	return ret;
+}
+
+static int mcp3911_write_raw(struct iio_dev *indio_dev,
+			    struct iio_chan_spec const *channel, int val,
+			    int val2, long mask)
+{

drivers/iio/adc/mcp3911.c line 164

Quoted 10 lines

drivers/iio/adc/mcp3911.c new file +10 -0

+	struct mcp3911 *adc = iio_priv(indio_dev);
+	int ret = -EINVAL;
+
+	mutex_lock(&adc->lock);
+	switch (mask) {
+	case IIO_CHAN_INFO_OFFSET:
+		if (val2 != 0) {
+			ret = -EINVAL;
+			goto out;
+		}  

Nitpick that I don't care about enough to delay on this. Could have moved the lock into the case statement then done the check outside the lock which would have been slightly nicer.

Quoted 189 lines

drivers/iio/adc/mcp3911.c new file +189 -0

+
+		/* Write offset */
+		ret = mcp3911_write(adc, MCP3911_OFFCAL(channel->channel), val,
+				3);
+		if (ret)
+			goto out;
+
+		/* Enable offset*/
+		ret = mcp3911_update(adc, MCP3911_REG_STATUSCOM,
+				MCP3911_STATUSCOM_EN_OFFCAL,
+				MCP3911_STATUSCOM_EN_OFFCAL, 2);
+		break;
+	}
+
+out:
+	mutex_unlock(&adc->lock);
+	return ret;
+}
+
+#define MCP3911_CHAN(idx) {					\
+		.type = IIO_VOLTAGE,				\
+		.indexed = 1,					\
+		.channel = idx,					\
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |	\
+			BIT(IIO_CHAN_INFO_OFFSET) |		\
+			BIT(IIO_CHAN_INFO_SCALE),		\
+}
+
+static const struct iio_chan_spec mcp3911_channels[] = {
+	MCP3911_CHAN(0),
+	MCP3911_CHAN(1),
+};
+
+static const struct iio_info mcp3911_info = {
+	.read_raw = mcp3911_read_raw,
+	.write_raw = mcp3911_write_raw,
+};
+
+static int mcp3911_config(struct mcp3911 *adc, struct device_node *of_node)
+{
+	u32 configreg;
+	int ret;
+
+	of_property_read_u32(of_node, "device-addr", &adc->dev_addr);
+	if (adc->dev_addr > 3) {
+		dev_err(&adc->spi->dev,
+				"invalid device address (%i). Must be in range 0-3.\n",
+				adc->dev_addr);
+		return -EINVAL;
+	}
+	dev_dbg(&adc->spi->dev, "use device address %i\n", adc->dev_addr);
+
+	ret = mcp3911_read(adc, MCP3911_REG_CONFIG, &configreg, 2);
+	if (ret)
+		return ret;
+
+	if (adc->vref) {
+		dev_dbg(&adc->spi->dev, "use external voltage reference\n");
+		configreg |= MCP3911_CONFIG_VREFEXT;
+	} else {
+		dev_dbg(&adc->spi->dev, "use internal voltage reference (1.2V)\n");
+		configreg &= ~MCP3911_CONFIG_VREFEXT;
+	}
+
+	if (adc->clki) {
+		dev_dbg(&adc->spi->dev, "use external clock as clocksource\n");
+		configreg |= MCP3911_CONFIG_CLKEXT;
+	} else {
+		dev_dbg(&adc->spi->dev, "use crystal oscillator as clocksource\n");
+		configreg &= ~MCP3911_CONFIG_CLKEXT;
+	}
+
+	return  mcp3911_write(adc, MCP3911_REG_CONFIG, configreg, 2);
+}
+
+static int mcp3911_probe(struct spi_device *spi)
+{
+	struct iio_dev *indio_dev;
+	struct mcp3911 *adc;
+	int ret;
+
+	indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*adc));
+	if (!indio_dev)
+		return -ENOMEM;
+
+	adc = iio_priv(indio_dev);
+	adc->spi = spi;
+
+	adc->vref = devm_regulator_get_optional(&adc->spi->dev, "vref");
+	if (IS_ERR(adc->vref)) {
+		if (PTR_ERR(adc->vref) == -ENODEV) {
+			adc->vref = NULL;
+		} else {
+			dev_err(&adc->spi->dev,
+					"failed to get regulator (%ld)\n",
+					PTR_ERR(adc->vref));
+			return PTR_ERR(adc->vref);
+		}
+
+	} else {
+		ret = regulator_enable(adc->vref);
+		if (ret)
+			return ret;
+	}
+
+	adc->clki = devm_clk_get(&adc->spi->dev, NULL);
+	if (IS_ERR(adc->clki)) {
+		if (PTR_ERR(adc->clki) == -ENOENT) {
+			adc->clki = NULL;
+		} else {
+			dev_err(&adc->spi->dev,
+					"failed to get adc clk (%ld)\n",
+					PTR_ERR(adc->clki));
+			ret = PTR_ERR(adc->clki);
+			goto reg_disable;
+		}
+	} else {
+		ret = clk_prepare_enable(adc->clki);
+		if (ret < 0) {
+			dev_err(&adc->spi->dev,
+				"Failed to enable clki: %d\n", ret);
+			goto reg_disable;
+		}
+	}
+
+	ret = mcp3911_config(adc, spi->dev.of_node);
+	if (ret)
+		goto clk_disable;
+
+	indio_dev->dev.parent = &spi->dev;
+	indio_dev->dev.of_node = spi->dev.of_node;
+	indio_dev->name = spi_get_device_id(spi)->name;
+	indio_dev->modes = INDIO_DIRECT_MODE;
+	indio_dev->info = &mcp3911_info;
+	spi_set_drvdata(spi, indio_dev);
+
+	indio_dev->channels = mcp3911_channels;
+	indio_dev->num_channels = ARRAY_SIZE(mcp3911_channels);
+
+	mutex_init(&adc->lock);
+
+	ret = iio_device_register(indio_dev);
+	if (ret)
+		goto clk_disable;
+
+	return ret;
+
+clk_disable:
+	clk_disable_unprepare(adc->clki);
+reg_disable:
+	if (adc->vref)
+		regulator_disable(adc->vref);
+
+	return ret;
+}
+
+static int mcp3911_remove(struct spi_device *spi)
+{
+	struct iio_dev *indio_dev = spi_get_drvdata(spi);
+	struct mcp3911 *adc = iio_priv(indio_dev);
+
+	iio_device_unregister(indio_dev);
+
+	clk_disable_unprepare(adc->clki);
+	if (adc->vref)
+		regulator_disable(adc->vref);
+
+	return 0;
+}
+
+static const struct of_device_id mcp3911_dt_ids[] = {
+	{ .compatible = "microchip,mcp3911" },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, mcp3911_dt_ids);
+
+static const struct spi_device_id mcp3911_id[] = {
+	{ "mcp3911", 0 },
+	{ }
+};
+MODULE_DEVICE_TABLE(spi, mcp3911_id);
+
+static struct spi_driver mcp3911_driver = {
+	.driver = {
+		.name = "mcp3911",
+		.of_match_table = mcp3911_dt_ids,
+	},
+	.probe = mcp3911_probe,
+	.remove = mcp3911_remove,

Quoted 9 lines

drivers/iio/adc/mcp3911.c line 361

Quoted 8 lines

drivers/iio/adc/mcp3911.c new file +8 -0

+	.id_table = mcp3911_id,
+};
+module_spi_driver(mcp3911_driver);
+
+MODULE_AUTHOR("Marcus Folkesson <[email protected]>");
+MODULE_AUTHOR("Kent Gustavsson <[email protected]>");
+MODULE_DESCRIPTION("Microchip Technology MCP3911");
+MODULE_LICENSE("GPL v2");  

Best regards
Marcus Folkesson

Quoted 12 lines · On Sun, 19 Aug 2018 21:17:51 +0200 Marcus Folkesson…

Quoted 10 lines · Jonathan Cameron

Quoted 4 lines · On Wed, 8 Aug 2018 10:09:15 +0200 Marcus Folkesson…

MCP3911 is a dual channel Analog Front End (AFE) containing two synchronous sampling delta-sigma Analog-to-Digital Converters (ADC).

Co-Developed-by Kent Gustavsson <[email protected]>

checkpatch points out..
Co-developed-by is the 'official' form of the tag. I'll fixup. (first time I've seen one of these ;)

Quoted 3 lines

Yep, I also noticed that checkpatch is not Co-developed-by-aware yet. I tried to fix it, but Perl is just such a terrible language that I considered it impossible.

The version in mainline seems to be aware, it just wants Co-developed-by not Co-Developed-by!

(lower case d)