[PATCH v3 0/2] Add support for Microchip MCP41xxx/42xxx potentiometers

[PATCH v3 0/2] Add support for Microchip MCP41xxx/42xxx potentiometers

[Chris Coffey]

Hello all,

This patch series adds device-tree documentation and driver support
for the Microchip MCP41xxx/42xxx family of digital potentiometers.

Changes in v3:
 - Get device names from mcp41010_cfg struct instead of spi device as
   suggested by Jonathan Cameron.
 - Refactor code structure in mcp41010_write_raw() as recommended by
   Jonathan Cameron.
 - Only call spi_get_device_id() when necessary to load config as
   suggested by Slawomir Stepien.
 - In mcp41010_probe(), return err to make static checkers happy as
   recommended by Jonathan Cameron.
 - Edit mcp41010_match struct members to fit on one line as suggested
   by Slawomir Stepien.
 - In device tree binding documentation, add company name to example
   as pointed out by Slawomir Stepien.
 - In device tree binding documentation, remove mcp41010 prefix from
   example as suggested by Jonathan Cameron.

Changes in v2:
 - Move device tree binding documentation to separate commit as
   pointed out by Himanshu Jha.
 - Remove explicit '= 0' initialization in mcp41010_type enum as
   recommended by Himanshu Jha.
 - Change MCP41010_WRITE from (0x01 << 4) to BIT(4) as recommended by
   Himanshu Jha.
 - Use of_device_get_match_data() to load configuration as 
   recommended by Peter Rosin. 
 - Rename MCP41010_WIPER_ENABLE to MCP41010_WIPER_CHANNEL as 
   suggested by Peter Rosin.
 - Remove CONFIG_OF build protections as recommended by Jonathan
   Cameron.
 - Remove of_match_ptr wrapper from mcp41010_driver struct as 
   recommended by Jonathan Cameron.
 - Remove blank line in mcp41010.c intro as recommended by Jonathan
   Cameron.

Chris Coffey (2):
  dt-bindings: iio: potentiometer: Add Microchip MCP41xxx/42xxx
  iio: potentiometer: Add driver for Microchip MCP41xxx/42xxx

 .../bindings/iio/potentiometer/mcp41010.txt        |  29 +++
 drivers/iio/potentiometer/Kconfig                  |  12 ++
 drivers/iio/potentiometer/Makefile                 |   1 +
 drivers/iio/potentiometer/mcp41010.c               | 204 +++++++++++++++++++++
 4 files changed, 246 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/iio/potentiometer/mcp41010.txt
 create mode 100644 drivers/iio/potentiometer/mcp41010.c

-- 
2.11.0

[PATCH v3 1/2] dt-bindings: iio: potentiometer: Add Microchip MCP41xxx/42xxx

[Chris Coffey]

This patch adds device tree documentation for the Microchip
MCP41xxx/42xxx family of digital potentiometers.

Signed-off-by: Chris Coffey <cmc@babblebit.net>
---
 .../bindings/iio/potentiometer/mcp41010.txt        | 29 ++++++++++++++++++++++
 1 file changed, 29 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/iio/potentiometer/mcp41010.txt

diff --git a/Documentation/devicetree/bindings/iio/potentiometer/mcp41010.txt b/Documentation/devicetree/bindings/iio/potentiometer/mcp41010.txt
new file mode 100644
index 0000000000..7dcf2071b7
--- /dev/null
+++ b/Documentation/devicetree/bindings/iio/potentiometer/mcp41010.txt
@@ -0,0 +1,29 @@
+* Microchip MCP41010/41050/41100/42010/42050/42100 Digital Potentiometer
+  driver
+
+Datasheet publicly available at:
+http://ww1.microchip.com/downloads/en/devicedoc/11195c.pdf
+
+The node for this driver must be a child node of a SPI controller, hence
+all mandatory properties described in
+
+        Documentation/devicetree/bindings/spi/spi-bus.txt
+
+must be specified.
+
+Required properties:
+	- compatible:  	Must be one of the following, depending on the
+			model:
+			"microchip,mcp41010"
+			"microchip,mcp41050"
+			"microchip,mcp41100"
+			"microchip,mcp42010"
+			"microchip,mcp42050"
+			"microchip,mcp42100"
+
+Example:
+potentiometer@0 {
+	compatible = "microchip,mcp41010";
+	reg = <0>;
+	spi-max-frequency = <500000>;
+};
-- 
2.11.0

[PATCH v3 2/2] iio: potentiometer: Add driver for Microchip MCP41xxx/42xxx

[Chris Coffey]

This patch adds driver support for the Microchip MCP41xxx/42xxx family
of digital potentiometers:

DEVICE      Wipers  Positions   Resistance (kOhm)
MCP41010    1       256         10
MCP41050    1       256         50
MCP41100    1       256         100
MCP42010    2       256         10
MCP42050    2       256         50
MCP42100    2       256         100

Datasheet: http://ww1.microchip.com/downloads/en/devicedoc/11195c.pdf

Signed-off-by: Chris Coffey <cmc@babblebit.net>
---
 drivers/iio/potentiometer/Kconfig    |  12 +++
 drivers/iio/potentiometer/Makefile   |   1 +
 drivers/iio/potentiometer/mcp41010.c | 204 +++++++++++++++++++++++++++++++++++
 3 files changed, 217 insertions(+)
 create mode 100644 drivers/iio/potentiometer/mcp41010.c

diff --git a/drivers/iio/potentiometer/Kconfig b/drivers/iio/potentiometer/Kconfig
index 79ec2eba49..6303cbe799 100644
--- a/drivers/iio/potentiometer/Kconfig
+++ b/drivers/iio/potentiometer/Kconfig
@@ -90,6 +90,18 @@ config MCP4531
 	  To compile this driver as a module, choose M here: the
 	  module will be called mcp4531.
 
+config MCP41010
+	tristate "Microchip MCP41xxx/MCP42xxx Digital Potentiometer driver"
+	depends on SPI
+	help
+	  Say yes here to build support for the Microchip
+	  MCP41010, MCP41050, MCP41100,
+	  MCP42010, MCP42050, MCP42100
+	  digital potentiometer chips.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called mcp41010.
+
 config TPL0102
 	tristate "Texas Instruments digital potentiometer driver"
 	depends on I2C
diff --git a/drivers/iio/potentiometer/Makefile b/drivers/iio/potentiometer/Makefile
index 4af657883c..8ff55138cf 100644
--- a/drivers/iio/potentiometer/Makefile
+++ b/drivers/iio/potentiometer/Makefile
@@ -11,4 +11,5 @@ obj-$(CONFIG_MAX5487) += max5487.o
 obj-$(CONFIG_MCP4018) += mcp4018.o
 obj-$(CONFIG_MCP4131) += mcp4131.o
 obj-$(CONFIG_MCP4531) += mcp4531.o
+obj-$(CONFIG_MCP41010) += mcp41010.o
 obj-$(CONFIG_TPL0102) += tpl0102.o
diff --git a/drivers/iio/potentiometer/mcp41010.c b/drivers/iio/potentiometer/mcp41010.c
new file mode 100644
index 0000000000..4a91066cb1
--- /dev/null
+++ b/drivers/iio/potentiometer/mcp41010.c
@@ -0,0 +1,204 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Industrial I/O driver for Microchip digital potentiometers
+ *
+ * Copyright (c) 2018 Chris Coffey <cmc@babblebit.net>
+ * Based on: Slawomir Stepien's code from mcp4131.c
+ *
+ * Datasheet: http://ww1.microchip.com/downloads/en/devicedoc/11195c.pdf
+ *
+ * DEVID	#Wipers	#Positions	Resistance (kOhm)
+ * mcp41010	1	256		10
+ * mcp41050	1	256		50
+ * mcp41100	1	256		100
+ * mcp42010	2	256		10
+ * mcp42050	2	256		50
+ * mcp42100	2	256		100
+ */
+
+#include <linux/cache.h>
+#include <linux/err.h>
+#include <linux/export.h>
+#include <linux/iio/iio.h>
+#include <linux/iio/types.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+#include <linux/spi/spi.h>
+
+#define MCP41010_MAX_WIPERS	2
+#define MCP41010_WRITE		BIT(4)
+#define MCP41010_WIPER_MAX	255
+#define MCP41010_WIPER_CHANNEL	BIT(0)
+
+struct mcp41010_cfg {
+	char name[16];
+	int wipers;
+	int kohms;
+};
+
+enum mcp41010_type {
+	MCP41010,
+	MCP41050,
+	MCP41100,
+	MCP42010,
+	MCP42050,
+	MCP42100,
+};
+
+static const struct mcp41010_cfg mcp41010_cfg[] = {
+	[MCP41010] = { .name = "mcp41010", .wipers = 1, .kohms =  10, },
+	[MCP41050] = { .name = "mcp41050", .wipers = 1, .kohms =  50, },
+	[MCP41100] = { .name = "mcp41100", .wipers = 1, .kohms = 100, },
+	[MCP42010] = { .name = "mcp42010", .wipers = 2, .kohms =  10, },
+	[MCP42050] = { .name = "mcp42050", .wipers = 2, .kohms =  50, },
+	[MCP42100] = { .name = "mcp42100", .wipers = 2, .kohms = 100, },
+};
+
+struct mcp41010_data {
+	struct spi_device *spi;
+	const struct mcp41010_cfg *cfg;
+	struct mutex lock; /* Protect write sequences */
+	unsigned int value[MCP41010_MAX_WIPERS]; /* Cache wiper values */
+	u8 buf[2] ____cacheline_aligned;
+};
+
+#define MCP41010_CHANNEL(ch) {					\
+	.type = IIO_RESISTANCE,					\
+	.indexed = 1,						\
+	.output = 1,						\
+	.channel = (ch),					\
+	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),		\
+	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),	\
+}
+
+static const struct iio_chan_spec mcp41010_channels[] = {
+	MCP41010_CHANNEL(0),
+	MCP41010_CHANNEL(1),
+};
+
+static int mcp41010_read_raw(struct iio_dev *indio_dev,
+			    struct iio_chan_spec const *chan,
+			    int *val, int *val2, long mask)
+{
+	struct mcp41010_data *data = iio_priv(indio_dev);
+	int channel = chan->channel;
+
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW:
+		*val = data->value[channel];
+		return IIO_VAL_INT;
+
+	case IIO_CHAN_INFO_SCALE:
+		*val = 1000 * data->cfg->kohms;
+		*val2 = MCP41010_WIPER_MAX;
+		return IIO_VAL_FRACTIONAL;
+	}
+
+	return -EINVAL;
+}
+
+static int mcp41010_write_raw(struct iio_dev *indio_dev,
+			     struct iio_chan_spec const *chan,
+			     int val, int val2, long mask)
+{
+	int err;
+	struct mcp41010_data *data = iio_priv(indio_dev);
+	int channel = chan->channel;
+
+	if (mask != IIO_CHAN_INFO_RAW)
+		return -EINVAL;
+
+	if (val > MCP41010_WIPER_MAX || val < 0)
+		return -EINVAL;
+
+	mutex_lock(&data->lock);
+
+	data->buf[0] = MCP41010_WIPER_CHANNEL << channel;
+	data->buf[0] |= MCP41010_WRITE;
+	data->buf[1] = val & 0xff;
+
+	err = spi_write(data->spi, data->buf, 2);
+	if (!err)
+		data->value[channel] = val;
+
+	mutex_unlock(&data->lock);
+
+	return err;
+}
+
+static const struct iio_info mcp41010_info = {
+	.read_raw = mcp41010_read_raw,
+	.write_raw = mcp41010_write_raw,
+};
+
+static int mcp41010_probe(struct spi_device *spi)
+{
+	int err;
+	struct device *dev = &spi->dev;
+	struct mcp41010_data *data;
+	struct iio_dev *indio_dev;
+
+	indio_dev = devm_iio_device_alloc(dev, sizeof(*data));
+	if (!indio_dev)
+		return -ENOMEM;
+
+	data = iio_priv(indio_dev);
+	spi_set_drvdata(spi, indio_dev);
+	data->spi = spi;
+	data->cfg = of_device_get_match_data(&spi->dev);
+	if (!data->cfg)
+		data->cfg = &mcp41010_cfg[spi_get_device_id(spi)->driver_data];
+
+	mutex_init(&data->lock);
+
+	indio_dev->dev.parent = dev;
+	indio_dev->info = &mcp41010_info;
+	indio_dev->channels = mcp41010_channels;
+	indio_dev->num_channels = data->cfg->wipers;
+	indio_dev->name = data->cfg->name;
+
+	err = devm_iio_device_register(dev, indio_dev);
+	if (err)
+		dev_info(&spi->dev, "Unable to register %s\n", indio_dev->name);
+
+	return err;
+}
+
+static const struct of_device_id mcp41010_match[] = {
+	{ .compatible = "microchip,mcp41010", .data = &mcp41010_cfg[MCP41010] },
+	{ .compatible = "microchip,mcp41050", .data = &mcp41010_cfg[MCP41050] },
+	{ .compatible = "microchip,mcp41100", .data = &mcp41010_cfg[MCP41100] },
+	{ .compatible = "microchip,mcp42010", .data = &mcp41010_cfg[MCP42010] },
+	{ .compatible = "microchip,mcp42050", .data = &mcp41010_cfg[MCP42050] },
+	{ .compatible = "microchip,mcp42100", .data = &mcp41010_cfg[MCP42100] },
+	{}
+};
+MODULE_DEVICE_TABLE(of, mcp41010_match);
+
+static const struct spi_device_id mcp41010_id[] = {
+	{ "mcp41010", MCP41010 },
+	{ "mcp41050", MCP41050 },
+	{ "mcp41100", MCP41100 },
+	{ "mcp42010", MCP42010 },
+	{ "mcp42050", MCP42050 },
+	{ "mcp42100", MCP42100 },
+	{}
+};
+MODULE_DEVICE_TABLE(spi, mcp41010_id);
+
+static struct spi_driver mcp41010_driver = {
+	.driver = {
+		.name	= "mcp41010",
+		.of_match_table = mcp41010_match,
+	},
+	.probe		= mcp41010_probe,
+	.id_table	= mcp41010_id,
+};
+
+module_spi_driver(mcp41010_driver);
+
+MODULE_AUTHOR("Chris Coffey <cmc@babblebit.net>");
+MODULE_DESCRIPTION("MCP41010 digital potentiometer");
+MODULE_LICENSE("GPL v2");
-- 
2.11.0

Re: [PATCH v3 2/2] iio: potentiometer: Add driver for Microchip MCP41xxx/42xxx

[Peter Meerwald-Stadler]

On Tue, 20 Nov 2018, Chris Coffey wrote:

Hello,

some minor comments below, otherwise looks good

regards, p.

> This patch adds driver support for the Microchip MCP41xxx/42xxx family
> of digital potentiometers:
> 
> DEVICE      Wipers  Positions   Resistance (kOhm)
> MCP41010    1       256         10
> MCP41050    1       256         50
> MCP41100    1       256         100
> MCP42010    2       256         10
> MCP42050    2       256         50
> MCP42100    2       256         100
> 
> Datasheet: http://ww1.microchip.com/downloads/en/devicedoc/11195c.pdf
> 
> Signed-off-by: Chris Coffey <cmc@babblebit.net>
> ---
>  drivers/iio/potentiometer/Kconfig    |  12 +++
>  drivers/iio/potentiometer/Makefile   |   1 +
>  drivers/iio/potentiometer/mcp41010.c | 204 +++++++++++++++++++++++++++++++++++
>  3 files changed, 217 insertions(+)
>  create mode 100644 drivers/iio/potentiometer/mcp41010.c
> 
> diff --git a/drivers/iio/potentiometer/Kconfig b/drivers/iio/potentiometer/Kconfig
> index 79ec2eba49..6303cbe799 100644
> --- a/drivers/iio/potentiometer/Kconfig
> +++ b/drivers/iio/potentiometer/Kconfig
> @@ -90,6 +90,18 @@ config MCP4531
>  	  To compile this driver as a module, choose M here: the
>  	  module will be called mcp4531.
>  
> +config MCP41010
> +	tristate "Microchip MCP41xxx/MCP42xxx Digital Potentiometer driver"
> +	depends on SPI
> +	help
> +	  Say yes here to build support for the Microchip
> +	  MCP41010, MCP41050, MCP41100,
> +	  MCP42010, MCP42050, MCP42100
> +	  digital potentiometer chips.
> +
> +	  To compile this driver as a module, choose M here: the
> +	  module will be called mcp41010.
> +
>  config TPL0102
>  	tristate "Texas Instruments digital potentiometer driver"
>  	depends on I2C
> diff --git a/drivers/iio/potentiometer/Makefile b/drivers/iio/potentiometer/Makefile
> index 4af657883c..8ff55138cf 100644
> --- a/drivers/iio/potentiometer/Makefile
> +++ b/drivers/iio/potentiometer/Makefile
> @@ -11,4 +11,5 @@ obj-$(CONFIG_MAX5487) += max5487.o
>  obj-$(CONFIG_MCP4018) += mcp4018.o
>  obj-$(CONFIG_MCP4131) += mcp4131.o
>  obj-$(CONFIG_MCP4531) += mcp4531.o
> +obj-$(CONFIG_MCP41010) += mcp41010.o
>  obj-$(CONFIG_TPL0102) += tpl0102.o
> diff --git a/drivers/iio/potentiometer/mcp41010.c b/drivers/iio/potentiometer/mcp41010.c
> new file mode 100644
> index 0000000000..4a91066cb1
> --- /dev/null
> +++ b/drivers/iio/potentiometer/mcp41010.c
> @@ -0,0 +1,204 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Industrial I/O driver for Microchip digital potentiometers
> + *
> + * Copyright (c) 2018 Chris Coffey <cmc@babblebit.net>
> + * Based on: Slawomir Stepien's code from mcp4131.c
> + *
> + * Datasheet: http://ww1.microchip.com/downloads/en/devicedoc/11195c.pdf
> + *
> + * DEVID	#Wipers	#Positions	Resistance (kOhm)
> + * mcp41010	1	256		10
> + * mcp41050	1	256		50
> + * mcp41100	1	256		100
> + * mcp42010	2	256		10
> + * mcp42050	2	256		50
> + * mcp42100	2	256		100
> + */
> +
> +#include <linux/cache.h>
> +#include <linux/err.h>
> +#include <linux/export.h>

wondering if export.h is needed?

> +#include <linux/iio/iio.h>
> +#include <linux/iio/types.h>
> +#include <linux/module.h>
> +#include <linux/mutex.h>
> +#include <linux/of.h>
> +#include <linux/of_device.h>
> +#include <linux/spi/spi.h>
> +
> +#define MCP41010_MAX_WIPERS	2
> +#define MCP41010_WRITE		BIT(4)
> +#define MCP41010_WIPER_MAX	255
> +#define MCP41010_WIPER_CHANNEL	BIT(0)
> +
> +struct mcp41010_cfg {
> +	char name[16];
> +	int wipers;
> +	int kohms;
> +};
> +
> +enum mcp41010_type {
> +	MCP41010,
> +	MCP41050,
> +	MCP41100,
> +	MCP42010,
> +	MCP42050,
> +	MCP42100,
> +};
> +
> +static const struct mcp41010_cfg mcp41010_cfg[] = {
> +	[MCP41010] = { .name = "mcp41010", .wipers = 1, .kohms =  10, },
> +	[MCP41050] = { .name = "mcp41050", .wipers = 1, .kohms =  50, },
> +	[MCP41100] = { .name = "mcp41100", .wipers = 1, .kohms = 100, },
> +	[MCP42010] = { .name = "mcp42010", .wipers = 2, .kohms =  10, },
> +	[MCP42050] = { .name = "mcp42050", .wipers = 2, .kohms =  50, },
> +	[MCP42100] = { .name = "mcp42100", .wipers = 2, .kohms = 100, },
> +};
> +
> +struct mcp41010_data {
> +	struct spi_device *spi;
> +	const struct mcp41010_cfg *cfg;
> +	struct mutex lock; /* Protect write sequences */
> +	unsigned int value[MCP41010_MAX_WIPERS]; /* Cache wiper values */
> +	u8 buf[2] ____cacheline_aligned;
> +};
> +
> +#define MCP41010_CHANNEL(ch) {					\
> +	.type = IIO_RESISTANCE,					\
> +	.indexed = 1,						\
> +	.output = 1,						\
> +	.channel = (ch),					\
> +	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),		\
> +	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),	\
> +}
> +
> +static const struct iio_chan_spec mcp41010_channels[] = {
> +	MCP41010_CHANNEL(0),
> +	MCP41010_CHANNEL(1),
> +};
> +
> +static int mcp41010_read_raw(struct iio_dev *indio_dev,
> +			    struct iio_chan_spec const *chan,
> +			    int *val, int *val2, long mask)
> +{
> +	struct mcp41010_data *data = iio_priv(indio_dev);
> +	int channel = chan->channel;
> +
> +	switch (mask) {
> +	case IIO_CHAN_INFO_RAW:
> +		*val = data->value[channel];
> +		return IIO_VAL_INT;
> +
> +	case IIO_CHAN_INFO_SCALE:
> +		*val = 1000 * data->cfg->kohms;
> +		*val2 = MCP41010_WIPER_MAX;
> +		return IIO_VAL_FRACTIONAL;
> +	}
> +
> +	return -EINVAL;
> +}
> +
> +static int mcp41010_write_raw(struct iio_dev *indio_dev,
> +			     struct iio_chan_spec const *chan,
> +			     int val, int val2, long mask)
> +{
> +	int err;
> +	struct mcp41010_data *data = iio_priv(indio_dev);
> +	int channel = chan->channel;
> +
> +	if (mask != IIO_CHAN_INFO_RAW)
> +		return -EINVAL;
> +
> +	if (val > MCP41010_WIPER_MAX || val < 0)
> +		return -EINVAL;
> +
> +	mutex_lock(&data->lock);
> +
> +	data->buf[0] = MCP41010_WIPER_CHANNEL << channel;
> +	data->buf[0] |= MCP41010_WRITE;
> +	data->buf[1] = val & 0xff;
> +
> +	err = spi_write(data->spi, data->buf, 2);

2 is the sizeof(data->buf)

> +	if (!err)
> +		data->value[channel] = val;
> +
> +	mutex_unlock(&data->lock);
> +
> +	return err;
> +}
> +
> +static const struct iio_info mcp41010_info = {
> +	.read_raw = mcp41010_read_raw,
> +	.write_raw = mcp41010_write_raw,
> +};
> +
> +static int mcp41010_probe(struct spi_device *spi)
> +{
> +	int err;
> +	struct device *dev = &spi->dev;
> +	struct mcp41010_data *data;
> +	struct iio_dev *indio_dev;
> +
> +	indio_dev = devm_iio_device_alloc(dev, sizeof(*data));
> +	if (!indio_dev)
> +		return -ENOMEM;
> +
> +	data = iio_priv(indio_dev);
> +	spi_set_drvdata(spi, indio_dev);
> +	data->spi = spi;
> +	data->cfg = of_device_get_match_data(&spi->dev);
> +	if (!data->cfg)
> +		data->cfg = &mcp41010_cfg[spi_get_device_id(spi)->driver_data];
> +
> +	mutex_init(&data->lock);
> +
> +	indio_dev->dev.parent = dev;
> +	indio_dev->info = &mcp41010_info;
> +	indio_dev->channels = mcp41010_channels;
> +	indio_dev->num_channels = data->cfg->wipers;
> +	indio_dev->name = data->cfg->name;
> +
> +	err = devm_iio_device_register(dev, indio_dev);
> +	if (err)
> +		dev_info(&spi->dev, "Unable to register %s\n", indio_dev->name);
> +
> +	return err;
> +}
> +
> +static const struct of_device_id mcp41010_match[] = {
> +	{ .compatible = "microchip,mcp41010", .data = &mcp41010_cfg[MCP41010] },
> +	{ .compatible = "microchip,mcp41050", .data = &mcp41010_cfg[MCP41050] },
> +	{ .compatible = "microchip,mcp41100", .data = &mcp41010_cfg[MCP41100] },
> +	{ .compatible = "microchip,mcp42010", .data = &mcp41010_cfg[MCP42010] },
> +	{ .compatible = "microchip,mcp42050", .data = &mcp41010_cfg[MCP42050] },
> +	{ .compatible = "microchip,mcp42100", .data = &mcp41010_cfg[MCP42100] },
> +	{}
> +};
> +MODULE_DEVICE_TABLE(of, mcp41010_match);
> +
> +static const struct spi_device_id mcp41010_id[] = {
> +	{ "mcp41010", MCP41010 },
> +	{ "mcp41050", MCP41050 },
> +	{ "mcp41100", MCP41100 },
> +	{ "mcp42010", MCP42010 },
> +	{ "mcp42050", MCP42050 },
> +	{ "mcp42100", MCP42100 },
> +	{}
> +};
> +MODULE_DEVICE_TABLE(spi, mcp41010_id);
> +
> +static struct spi_driver mcp41010_driver = {
> +	.driver = {
> +		.name	= "mcp41010",
> +		.of_match_table = mcp41010_match,
> +	},
> +	.probe		= mcp41010_probe,
> +	.id_table	= mcp41010_id,
> +};
> +
> +module_spi_driver(mcp41010_driver);
> +
> +MODULE_AUTHOR("Chris Coffey <cmc@babblebit.net>");
> +MODULE_DESCRIPTION("MCP41010 digital potentiometer");
> +MODULE_LICENSE("GPL v2");
> 

-- 

Peter Meerwald-Stadler
Mobile: +43 664 24 44 418

Re: [PATCH v3 2/2] iio: potentiometer: Add driver for Microchip MCP41xxx/42xxx

[Chris Coffey]

On Tue, Nov 20, 2018 at 03:30:05PM +0100, Peter Meerwald-Stadler wrote:
> On Tue, 20 Nov 2018, Chris Coffey wrote:
> 
> Hello,
> 
> some minor comments below, otherwise looks good
> 
> regards, p.
> 

Hi Peter,

Thank you for the review. One comment below.

> > This patch adds driver support for the Microchip MCP41xxx/42xxx family
> > of digital potentiometers:
> > 
> > DEVICE      Wipers  Positions   Resistance (kOhm)
> > MCP41010    1       256         10
> > MCP41050    1       256         50
> > MCP41100    1       256         100
> > MCP42010    2       256         10
> > MCP42050    2       256         50
> > MCP42100    2       256         100
> > 
> > Datasheet: http://ww1.microchip.com/downloads/en/devicedoc/11195c.pdf
> > 
> > Signed-off-by: Chris Coffey <cmc@babblebit.net>
> > ---
> >  drivers/iio/potentiometer/Kconfig    |  12 +++
> >  drivers/iio/potentiometer/Makefile   |   1 +
> >  drivers/iio/potentiometer/mcp41010.c | 204 +++++++++++++++++++++++++++++++++++
> >  3 files changed, 217 insertions(+)
> >  create mode 100644 drivers/iio/potentiometer/mcp41010.c
> > 
> > diff --git a/drivers/iio/potentiometer/Kconfig b/drivers/iio/potentiometer/Kconfig
> > index 79ec2eba49..6303cbe799 100644
> > --- a/drivers/iio/potentiometer/Kconfig
> > +++ b/drivers/iio/potentiometer/Kconfig
> > @@ -90,6 +90,18 @@ config MCP4531
> >  	  To compile this driver as a module, choose M here: the
> >  	  module will be called mcp4531.
> >  
> > +config MCP41010
> > +	tristate "Microchip MCP41xxx/MCP42xxx Digital Potentiometer driver"
> > +	depends on SPI
> > +	help
> > +	  Say yes here to build support for the Microchip
> > +	  MCP41010, MCP41050, MCP41100,
> > +	  MCP42010, MCP42050, MCP42100
> > +	  digital potentiometer chips.
> > +
> > +	  To compile this driver as a module, choose M here: the
> > +	  module will be called mcp41010.
> > +
> >  config TPL0102
> >  	tristate "Texas Instruments digital potentiometer driver"
> >  	depends on I2C
> > diff --git a/drivers/iio/potentiometer/Makefile b/drivers/iio/potentiometer/Makefile
> > index 4af657883c..8ff55138cf 100644
> > --- a/drivers/iio/potentiometer/Makefile
> > +++ b/drivers/iio/potentiometer/Makefile
> > @@ -11,4 +11,5 @@ obj-$(CONFIG_MAX5487) += max5487.o
> >  obj-$(CONFIG_MCP4018) += mcp4018.o
> >  obj-$(CONFIG_MCP4131) += mcp4131.o
> >  obj-$(CONFIG_MCP4531) += mcp4531.o
> > +obj-$(CONFIG_MCP41010) += mcp41010.o
> >  obj-$(CONFIG_TPL0102) += tpl0102.o
> > diff --git a/drivers/iio/potentiometer/mcp41010.c b/drivers/iio/potentiometer/mcp41010.c
> > new file mode 100644
> > index 0000000000..4a91066cb1
> > --- /dev/null
> > +++ b/drivers/iio/potentiometer/mcp41010.c
> > @@ -0,0 +1,204 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +/*
> > + * Industrial I/O driver for Microchip digital potentiometers
> > + *
> > + * Copyright (c) 2018 Chris Coffey <cmc@babblebit.net>
> > + * Based on: Slawomir Stepien's code from mcp4131.c
> > + *
> > + * Datasheet: http://ww1.microchip.com/downloads/en/devicedoc/11195c.pdf
> > + *
> > + * DEVID	#Wipers	#Positions	Resistance (kOhm)
> > + * mcp41010	1	256		10
> > + * mcp41050	1	256		50
> > + * mcp41100	1	256		100
> > + * mcp42010	2	256		10
> > + * mcp42050	2	256		50
> > + * mcp42100	2	256		100
> > + */
> > +
> > +#include <linux/cache.h>
> > +#include <linux/err.h>
> > +#include <linux/export.h>
> 
> wondering if export.h is needed?
> 

You're right; turns out it's not needed. I'll fix this in v4.

[snip]

Re: [PATCH v3 1/2] dt-bindings: iio: potentiometer: Add Microchip MCP41xxx/42xxx

[Jonathan Cameron]

On Tue, 20 Nov 2018 14:17:12 +0000
Chris Coffey <cmc@babblebit.net> wrote:

> This patch adds device tree documentation for the Microchip
> MCP41xxx/42xxx family of digital potentiometers.
> 
> Signed-off-by: Chris Coffey <cmc@babblebit.net>
> ---
>  .../bindings/iio/potentiometer/mcp41010.txt        | 29 ++++++++++++++++++++++
>  1 file changed, 29 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/iio/potentiometer/mcp41010.txt
> 
> diff --git a/Documentation/devicetree/bindings/iio/potentiometer/mcp41010.txt b/Documentation/devicetree/bindings/iio/potentiometer/mcp41010.txt
> new file mode 100644
> index 0000000000..7dcf2071b7
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/iio/potentiometer/mcp41010.txt
> @@ -0,0 +1,29 @@
> +* Microchip MCP41010/41050/41100/42010/42050/42100 Digital Potentiometer
> +  driver
I'll channel my inner Rob ;)  Bindings are for devices, not drivers
(basically don't mention driver anywhere)

It's trivial (and common) so I just tidied it up whilst applying.

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

Thanks,

Jonathan

> +
> +Datasheet publicly available at:
> +http://ww1.microchip.com/downloads/en/devicedoc/11195c.pdf
> +
> +The node for this driver must be a child node of a SPI controller, hence
> +all mandatory properties described in
> +
> +        Documentation/devicetree/bindings/spi/spi-bus.txt
> +
> +must be specified.
> +
> +Required properties:
> +	- compatible:  	Must be one of the following, depending on the
> +			model:
> +			"microchip,mcp41010"
> +			"microchip,mcp41050"
> +			"microchip,mcp41100"
> +			"microchip,mcp42010"
> +			"microchip,mcp42050"
> +			"microchip,mcp42100"
> +
> +Example:
> +potentiometer@0 {
> +	compatible = "microchip,mcp41010";
> +	reg = <0>;
> +	spi-max-frequency = <500000>;
> +};

Re: [PATCH v3 2/2] iio: potentiometer: Add driver for Microchip MCP41xxx/42xxx

[Jonathan Cameron]

On Tue, 20 Nov 2018 22:20:11 +0000
Chris Coffey <cmc@babblebit.net> wrote:

> On Tue, Nov 20, 2018 at 03:30:05PM +0100, Peter Meerwald-Stadler wrote:
> > On Tue, 20 Nov 2018, Chris Coffey wrote:
> > 
> > Hello,
> > 
> > some minor comments below, otherwise looks good
> > 
> > regards, p.
> >   
> 
> Hi Peter,
> 
> Thank you for the review. One comment below.
> 
> > > This patch adds driver support for the Microchip MCP41xxx/42xxx family
> > > of digital potentiometers:
> > > 
> > > DEVICE      Wipers  Positions   Resistance (kOhm)
> > > MCP41010    1       256         10
> > > MCP41050    1       256         50
> > > MCP41100    1       256         100
> > > MCP42010    2       256         10
> > > MCP42050    2       256         50
> > > MCP42100    2       256         100
> > > 
> > > Datasheet: http://ww1.microchip.com/downloads/en/devicedoc/11195c.pdf
> > > 
> > > Signed-off-by: Chris Coffey <cmc@babblebit.net>
> > > ---
> > >  drivers/iio/potentiometer/Kconfig    |  12 +++
> > >  drivers/iio/potentiometer/Makefile   |   1 +
> > >  drivers/iio/potentiometer/mcp41010.c | 204 +++++++++++++++++++++++++++++++++++
> > >  3 files changed, 217 insertions(+)
> > >  create mode 100644 drivers/iio/potentiometer/mcp41010.c
> > > 
> > > diff --git a/drivers/iio/potentiometer/Kconfig b/drivers/iio/potentiometer/Kconfig
> > > index 79ec2eba49..6303cbe799 100644
> > > --- a/drivers/iio/potentiometer/Kconfig
> > > +++ b/drivers/iio/potentiometer/Kconfig
> > > @@ -90,6 +90,18 @@ config MCP4531
> > >  	  To compile this driver as a module, choose M here: the
> > >  	  module will be called mcp4531.
> > >  
> > > +config MCP41010
> > > +	tristate "Microchip MCP41xxx/MCP42xxx Digital Potentiometer driver"
> > > +	depends on SPI
> > > +	help
> > > +	  Say yes here to build support for the Microchip
> > > +	  MCP41010, MCP41050, MCP41100,
> > > +	  MCP42010, MCP42050, MCP42100
> > > +	  digital potentiometer chips.
> > > +
> > > +	  To compile this driver as a module, choose M here: the
> > > +	  module will be called mcp41010.
> > > +
> > >  config TPL0102
> > >  	tristate "Texas Instruments digital potentiometer driver"
> > >  	depends on I2C
> > > diff --git a/drivers/iio/potentiometer/Makefile b/drivers/iio/potentiometer/Makefile
> > > index 4af657883c..8ff55138cf 100644
> > > --- a/drivers/iio/potentiometer/Makefile
> > > +++ b/drivers/iio/potentiometer/Makefile
> > > @@ -11,4 +11,5 @@ obj-$(CONFIG_MAX5487) += max5487.o
> > >  obj-$(CONFIG_MCP4018) += mcp4018.o
> > >  obj-$(CONFIG_MCP4131) += mcp4131.o
> > >  obj-$(CONFIG_MCP4531) += mcp4531.o
> > > +obj-$(CONFIG_MCP41010) += mcp41010.o
> > >  obj-$(CONFIG_TPL0102) += tpl0102.o
> > > diff --git a/drivers/iio/potentiometer/mcp41010.c b/drivers/iio/potentiometer/mcp41010.c
> > > new file mode 100644
> > > index 0000000000..4a91066cb1
> > > --- /dev/null
> > > +++ b/drivers/iio/potentiometer/mcp41010.c
> > > @@ -0,0 +1,204 @@
> > > +// SPDX-License-Identifier: GPL-2.0
> > > +/*
> > > + * Industrial I/O driver for Microchip digital potentiometers
> > > + *
> > > + * Copyright (c) 2018 Chris Coffey <cmc@babblebit.net>
> > > + * Based on: Slawomir Stepien's code from mcp4131.c
> > > + *
> > > + * Datasheet: http://ww1.microchip.com/downloads/en/devicedoc/11195c.pdf
> > > + *
> > > + * DEVID	#Wipers	#Positions	Resistance (kOhm)
> > > + * mcp41010	1	256		10
> > > + * mcp41050	1	256		50
> > > + * mcp41100	1	256		100
> > > + * mcp42010	2	256		10
> > > + * mcp42050	2	256		50
> > > + * mcp42100	2	256		100
> > > + */
> > > +
> > > +#include <linux/cache.h>
> > > +#include <linux/err.h>
> > > +#include <linux/export.h>  
> > 
> > wondering if export.h is needed?
> >   
> 
> You're right; turns out it's not needed. I'll fix this in v4.
> 
> [snip]
Given both the issues Peter raised were trivial and I couldn't
see any others, I've applied this with the changes Peter suggested.

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

Thanks,

Jonathan

Re: [PATCH v3 2/2] iio: potentiometer: Add driver for Microchip MCP41xxx/42xxx

[Chris Coffey]

On Sun, Nov 25, 2018 at 12:30:28PM +0000, Jonathan Cameron wrote:
> On Tue, 20 Nov 2018 22:20:11 +0000
> Chris Coffey <cmc@babblebit.net> wrote:
> 
> > On Tue, Nov 20, 2018 at 03:30:05PM +0100, Peter Meerwald-Stadler wrote:
> > > On Tue, 20 Nov 2018, Chris Coffey wrote:
> > > 
> > > Hello,
> > > 
> > > some minor comments below, otherwise looks good
> > > 
> > > regards, p.
> > >   
> > 
> > Hi Peter,
> > 
> > Thank you for the review. One comment below.
> > 
> > > > This patch adds driver support for the Microchip MCP41xxx/42xxx family
> > > > of digital potentiometers:
> > > > 
> > > > DEVICE      Wipers  Positions   Resistance (kOhm)
> > > > MCP41010    1       256         10
> > > > MCP41050    1       256         50
> > > > MCP41100    1       256         100
> > > > MCP42010    2       256         10
> > > > MCP42050    2       256         50
> > > > MCP42100    2       256         100
> > > > 
> > > > Datasheet: http://ww1.microchip.com/downloads/en/devicedoc/11195c.pdf
> > > > 
> > > > Signed-off-by: Chris Coffey <cmc@babblebit.net>
> > > > ---
> > > >  drivers/iio/potentiometer/Kconfig    |  12 +++
> > > >  drivers/iio/potentiometer/Makefile   |   1 +
> > > >  drivers/iio/potentiometer/mcp41010.c | 204 +++++++++++++++++++++++++++++++++++
> > > >  3 files changed, 217 insertions(+)
> > > >  create mode 100644 drivers/iio/potentiometer/mcp41010.c
> > > > 
> > > > diff --git a/drivers/iio/potentiometer/Kconfig b/drivers/iio/potentiometer/Kconfig
> > > > index 79ec2eba49..6303cbe799 100644
> > > > --- a/drivers/iio/potentiometer/Kconfig
> > > > +++ b/drivers/iio/potentiometer/Kconfig
> > > > @@ -90,6 +90,18 @@ config MCP4531
> > > >  	  To compile this driver as a module, choose M here: the
> > > >  	  module will be called mcp4531.
> > > >  
> > > > +config MCP41010
> > > > +	tristate "Microchip MCP41xxx/MCP42xxx Digital Potentiometer driver"
> > > > +	depends on SPI
> > > > +	help
> > > > +	  Say yes here to build support for the Microchip
> > > > +	  MCP41010, MCP41050, MCP41100,
> > > > +	  MCP42010, MCP42050, MCP42100
> > > > +	  digital potentiometer chips.
> > > > +
> > > > +	  To compile this driver as a module, choose M here: the
> > > > +	  module will be called mcp41010.
> > > > +
> > > >  config TPL0102
> > > >  	tristate "Texas Instruments digital potentiometer driver"
> > > >  	depends on I2C
> > > > diff --git a/drivers/iio/potentiometer/Makefile b/drivers/iio/potentiometer/Makefile
> > > > index 4af657883c..8ff55138cf 100644
> > > > --- a/drivers/iio/potentiometer/Makefile
> > > > +++ b/drivers/iio/potentiometer/Makefile
> > > > @@ -11,4 +11,5 @@ obj-$(CONFIG_MAX5487) += max5487.o
> > > >  obj-$(CONFIG_MCP4018) += mcp4018.o
> > > >  obj-$(CONFIG_MCP4131) += mcp4131.o
> > > >  obj-$(CONFIG_MCP4531) += mcp4531.o
> > > > +obj-$(CONFIG_MCP41010) += mcp41010.o
> > > >  obj-$(CONFIG_TPL0102) += tpl0102.o
> > > > diff --git a/drivers/iio/potentiometer/mcp41010.c b/drivers/iio/potentiometer/mcp41010.c
> > > > new file mode 100644
> > > > index 0000000000..4a91066cb1
> > > > --- /dev/null
> > > > +++ b/drivers/iio/potentiometer/mcp41010.c
> > > > @@ -0,0 +1,204 @@
> > > > +// SPDX-License-Identifier: GPL-2.0
> > > > +/*
> > > > + * Industrial I/O driver for Microchip digital potentiometers
> > > > + *
> > > > + * Copyright (c) 2018 Chris Coffey <cmc@babblebit.net>
> > > > + * Based on: Slawomir Stepien's code from mcp4131.c
> > > > + *
> > > > + * Datasheet: http://ww1.microchip.com/downloads/en/devicedoc/11195c.pdf
> > > > + *
> > > > + * DEVID	#Wipers	#Positions	Resistance (kOhm)
> > > > + * mcp41010	1	256		10
> > > > + * mcp41050	1	256		50
> > > > + * mcp41100	1	256		100
> > > > + * mcp42010	2	256		10
> > > > + * mcp42050	2	256		50
> > > > + * mcp42100	2	256		100
> > > > + */
> > > > +
> > > > +#include <linux/cache.h>
> > > > +#include <linux/err.h>
> > > > +#include <linux/export.h>  
> > > 
> > > wondering if export.h is needed?
> > >   
> > 
> > You're right; turns out it's not needed. I'll fix this in v4.
> > 
> > [snip]
> Given both the issues Peter raised were trivial and I couldn't
> see any others, I've applied this with the changes Peter suggested.
> 
> Applied to the togreg branch of iio.git and pushed out as testing
> for the autobuilders to play with it.
> 
> Thanks,
> 
> Jonathan
> 

Brilliant. Thanks again to you and everyone else for the reviews and
feedback.

Chris