[PATCH v4 1/3] iio: adc: add support for mcp3911

[PATCH v4 1/3] iio: adc: add support for mcp3911

[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 <kent@minoris.se>
Signed-off-by: Kent Gustavsson <kent@minoris.se>
Signed-off-by: Marcus Folkesson <marcus.folkesson@gmail.com>
---

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

diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
index 15606f237480..f9a41fa96fcc 100644
--- a/drivers/iio/adc/Kconfig
+++ b/drivers/iio/adc/Kconfig
@@ -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
diff --git a/drivers/iio/adc/Makefile b/drivers/iio/adc/Makefile
index 28a9423997f3..3cfebfff7d26 100644
--- a/drivers/iio/adc/Makefile
+++ b/drivers/iio/adc/Makefile
@@ -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
diff --git a/drivers/iio/adc/mcp3911.c b/drivers/iio/adc/mcp3911.c
new file mode 100644
index 000000000000..540c8fbcce89
--- /dev/null
+++ b/drivers/iio/adc/mcp3911.c
@@ -0,0 +1,361 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Driver for Microchip MCP3911, Two-channel Analog Front End
+ *
+ * Copyright (C) 2018 Marcus Folkesson <marcus.folkesson@gmail.com>
+ * Copyright (C) 2018 Kent Gustavsson <kent@minoris.se>
+ */
+#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;
+
+	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);
+	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)
+{
+	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;
+		}
+
+		/* 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 <marcus.folkesson@gmail.com>");
+MODULE_AUTHOR("Kent Gustavsson <kent@minoris.se>");
+MODULE_DESCRIPTION("Microchip Technology MCP3911");
+MODULE_LICENSE("GPL v2");
-- 
2.11.0.rc2

[PATCH v4 2/3] dt-bindings: iio: adc: add bindings for mcp3911

[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 <kent@minoris.se>
Signed-off-by: Kent Gustavsson <kent@minoris.se>
Signed-off-by: Marcus Folkesson <marcus.folkesson@gmail.com>
Reviewed-by: Rob Herring <robh@kernel.org>
---

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

diff --git a/Documentation/devicetree/bindings/iio/adc/mcp3911.txt b/Documentation/devicetree/bindings/iio/adc/mcp3911.txt
new file mode 100644
index 000000000000..3071f48fb30b
--- /dev/null
+++ b/Documentation/devicetree/bindings/iio/adc/mcp3911.txt
@@ -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>;
+};
-- 
2.11.0.rc2

Re: [PATCH v4 2/3] dt-bindings: iio: adc: add bindings for mcp3911

[Jonathan Cameron]

On Wed,  8 Aug 2018 10:09:16 +0200
Marcus Folkesson <marcus.folkesson@gmail.com> wrote:

> 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 <kent@minoris.se>
> Signed-off-by: Kent Gustavsson <kent@minoris.se>
> Signed-off-by: Marcus Folkesson <marcus.folkesson@gmail.com>
> Reviewed-by: Rob Herring <robh@kernel.org>

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

thanks,

Jonathan
> ---
> 
> 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
> 
> diff --git a/Documentation/devicetree/bindings/iio/adc/mcp3911.txt b/Documentation/devicetree/bindings/iio/adc/mcp3911.txt
> new file mode 100644
> index 000000000000..3071f48fb30b
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/iio/adc/mcp3911.txt
> @@ -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>;
> +};

[PATCH v4 3/3] MAINTAINERS: Add entry for mcp3911 ADC driver

[Marcus Folkesson]

Add an entry for mcp3911 ADC driver and add myself and
Kent Gustavsson as maintainers of this driver.

Co-Developed-by: Kent Gustavsson <kent@minoris.se>
Signed-off-by: Kent Gustavsson <kent@minoris.se>
Signed-off-by: Marcus Folkesson <marcus.folkesson@gmail.com>
---

Notes:
    v4:
    	- add Kent as co-developer
    v3:
    	- no changes
    v2:
    	- no changes

 MAINTAINERS | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/MAINTAINERS b/MAINTAINERS
index 79bb02ff812f..9276da915d9d 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -9271,6 +9271,14 @@ L:	netdev@vger.kernel.org
 S:	Maintained
 F:	drivers/net/ethernet/microchip/lan743x_*
 
+MICROCHIP / ATMEL MCP3911 ADC DRIVER
+M:	Marcus Folkesson <marcus.folkesson@gmail.com>
+M:	Kent Gustavsson <kent@minoris.se>
+L:	linux-iio@vger.kernel.org
+S:	Supported
+F:	drivers/iio/adc/mcp3911.c
+F:	Documentation/devicetree/bindings/iio/adc/mcp3911.txt
+
 MICROCHIP USB251XB DRIVER
 M:	Richard Leitner <richard.leitner@skidata.com>
 L:	linux-usb@vger.kernel.org
-- 
2.11.0.rc2

Re: [PATCH v4 1/3] iio: adc: add support for mcp3911

[Jonathan Cameron]

On Wed,  8 Aug 2018 10:09:15 +0200
Marcus Folkesson <marcus.folkesson@gmail.com> wrote:

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

> Signed-off-by: Kent Gustavsson <kent@minoris.se>
> Signed-off-by: Marcus Folkesson <marcus.folkesson@gmail.com>
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

> ---
> 
> 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
> 
> diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
> index 15606f237480..f9a41fa96fcc 100644
> --- a/drivers/iio/adc/Kconfig
> +++ b/drivers/iio/adc/Kconfig
> @@ -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
> diff --git a/drivers/iio/adc/Makefile b/drivers/iio/adc/Makefile
> index 28a9423997f3..3cfebfff7d26 100644
> --- a/drivers/iio/adc/Makefile
> +++ b/drivers/iio/adc/Makefile
> @@ -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
> diff --git a/drivers/iio/adc/mcp3911.c b/drivers/iio/adc/mcp3911.c
> new file mode 100644
> index 000000000000..540c8fbcce89
> --- /dev/null
> +++ b/drivers/iio/adc/mcp3911.c
> @@ -0,0 +1,361 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Driver for Microchip MCP3911, Two-channel Analog Front End
> + *
> + * Copyright (C) 2018 Marcus Folkesson <marcus.folkesson@gmail.com>
> + * Copyright (C) 2018 Kent Gustavsson <kent@minoris.se>
> + */
> +#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;
> +
> +	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.

> +	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)
> +{
> +	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.
> +
> +		/* 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 <marcus.folkesson@gmail.com>");
> +MODULE_AUTHOR("Kent Gustavsson <kent@minoris.se>");
> +MODULE_DESCRIPTION("Microchip Technology MCP3911");
> +MODULE_LICENSE("GPL v2");

Re: [PATCH v4 1/3] iio: adc: add support for mcp3911

[Marcus Folkesson]

[-- Attachment #1: Type: text/plain, Size: 14491 bytes --]

On Sun, Aug 19, 2018 at 08:02:57PM +0100, Jonathan Cameron wrote:
> On Wed,  8 Aug 2018 10:09:15 +0200
> Marcus Folkesson <marcus.folkesson@gmail.com> wrote:
> 
> > 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 <kent@minoris.se>
> 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.

> 
> > Signed-off-by: Kent Gustavsson <kent@minoris.se>
> > Signed-off-by: Marcus Folkesson <marcus.folkesson@gmail.com>
> 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.
> 
> Jonathan
> 
> > ---
> > 
> > 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
> > 
> > diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
> > index 15606f237480..f9a41fa96fcc 100644
> > --- a/drivers/iio/adc/Kconfig
> > +++ b/drivers/iio/adc/Kconfig
> > @@ -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
> > diff --git a/drivers/iio/adc/Makefile b/drivers/iio/adc/Makefile
> > index 28a9423997f3..3cfebfff7d26 100644
> > --- a/drivers/iio/adc/Makefile
> > +++ b/drivers/iio/adc/Makefile
> > @@ -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
> > diff --git a/drivers/iio/adc/mcp3911.c b/drivers/iio/adc/mcp3911.c
> > new file mode 100644
> > index 000000000000..540c8fbcce89
> > --- /dev/null
> > +++ b/drivers/iio/adc/mcp3911.c
> > @@ -0,0 +1,361 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +/*
> > + * Driver for Microchip MCP3911, Two-channel Analog Front End
> > + *
> > + * Copyright (C) 2018 Marcus Folkesson <marcus.folkesson@gmail.com>
> > + * Copyright (C) 2018 Kent Gustavsson <kent@minoris.se>
> > + */
> > +#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;
> > +
> > +	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.
> 
> > +	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)
> > +{
> > +	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.
> > +
> > +		/* 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 <marcus.folkesson@gmail.com>");
> > +MODULE_AUTHOR("Kent Gustavsson <kent@minoris.se>");
> > +MODULE_DESCRIPTION("Microchip Technology MCP3911");
> > +MODULE_LICENSE("GPL v2");
> 

Best regards
Marcus Folkesson

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Re: [PATCH v4 1/3] iio: adc: add support for mcp3911

[Jonathan Cameron]

On Sun, 19 Aug 2018 21:17:51 +0200
Marcus Folkesson <marcus.folkesson@gmail.com> wrote:

> On Sun, Aug 19, 2018 at 08:02:57PM +0100, Jonathan Cameron wrote:
> > On Wed,  8 Aug 2018 10:09:15 +0200
> > Marcus Folkesson <marcus.folkesson@gmail.com> wrote:
> >   
> > > 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 <kent@minoris.se>  
> > 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.

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

(lower case d)
> 
> >   
> > > Signed-off-by: Kent Gustavsson <kent@minoris.se>
> > > Signed-off-by: Marcus Folkesson <marcus.folkesson@gmail.com>  
> > 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.
> > 
> > Jonathan
> >   
> > > ---
> > > 
> > > 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
> > > 
> > > diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
> > > index 15606f237480..f9a41fa96fcc 100644
> > > --- a/drivers/iio/adc/Kconfig
> > > +++ b/drivers/iio/adc/Kconfig
> > > @@ -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
> > > diff --git a/drivers/iio/adc/Makefile b/drivers/iio/adc/Makefile
> > > index 28a9423997f3..3cfebfff7d26 100644
> > > --- a/drivers/iio/adc/Makefile
> > > +++ b/drivers/iio/adc/Makefile
> > > @@ -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
> > > diff --git a/drivers/iio/adc/mcp3911.c b/drivers/iio/adc/mcp3911.c
> > > new file mode 100644
> > > index 000000000000..540c8fbcce89
> > > --- /dev/null
> > > +++ b/drivers/iio/adc/mcp3911.c
> > > @@ -0,0 +1,361 @@
> > > +// SPDX-License-Identifier: GPL-2.0
> > > +/*
> > > + * Driver for Microchip MCP3911, Two-channel Analog Front End
> > > + *
> > > + * Copyright (C) 2018 Marcus Folkesson <marcus.folkesson@gmail.com>
> > > + * Copyright (C) 2018 Kent Gustavsson <kent@minoris.se>
> > > + */
> > > +#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;
> > > +
> > > +	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.
> >   
> > > +	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)
> > > +{
> > > +	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.  
> > > +
> > > +		/* 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 <marcus.folkesson@gmail.com>");
> > > +MODULE_AUTHOR("Kent Gustavsson <kent@minoris.se>");
> > > +MODULE_DESCRIPTION("Microchip Technology MCP3911");
> > > +MODULE_LICENSE("GPL v2");  
> >   
> 
> Best regards
> Marcus Folkesson

Re: [PATCH v4 1/3] iio: adc: add support for mcp3911

[Marcus Folkesson]

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On Sun, Aug 19, 2018 at 08:29:43PM +0100, Jonathan Cameron wrote:
> On Sun, 19 Aug 2018 21:17:51 +0200
> Marcus Folkesson <marcus.folkesson@gmail.com> wrote:
> 
> > On Sun, Aug 19, 2018 at 08:02:57PM +0100, Jonathan Cameron wrote:
> > > On Wed,  8 Aug 2018 10:09:15 +0200
> > > Marcus Folkesson <marcus.folkesson@gmail.com> wrote:
> > >   
> > > > 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 <kent@minoris.se>  
> > > 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.
> 
> The version in mainline seems to be aware, it just wants
> Co-developed-by not Co-Developed-by!
> 
> (lower case d)

I just noticed that the tag was renamed from Co-Developed-by to
Co-developed-by in e474785a12b46230ecf9f3663166b0de1175bcdc.

I must have been reading the documentation from an older tree...

/Marcus

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