[PATCH 0/2] iio: ad5272: Add support for Analog Devices digital potentiometers

[PATCH 0/2] iio: ad5272: Add support for Analog Devices digital potentiometers

[Phil Reid]

Add documentation and driver for the Analog Devices 5272.

Driver currently doesn't support programing the RDAC position to 
non-volatile memory. 

Phil Reid (2):
  dt-bindings: ad5272: Add bindings for Analog Devices digital
    potentiometers
  iio: ad5272: Add support for Analog Devices digital potentiometers

 .../bindings/iio/potentiometer/ad5272.txt          |  27 +++
 drivers/iio/potentiometer/Kconfig                  |  10 +
 drivers/iio/potentiometer/Makefile                 |   1 +
 drivers/iio/potentiometer/ad5272.c                 | 219 +++++++++++++++++++++
 4 files changed, 257 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/iio/potentiometer/ad5272.txt
 create mode 100644 drivers/iio/potentiometer/ad5272.c

-- 
1.8.3.1

[PATCH 1/2] dt-bindings: ad5272: Add bindings for Analog Devices digital potentiometers

[Phil Reid]

Add binding documentation for Analog Devices AD5272 and AD5274 digital
potentiometer devices.

Signed-off-by: Phil Reid <preid-qgqNFa1JUf/o2iN0hyhwsIdd74u8MsAO@public.gmane.org>
---
 .../bindings/iio/potentiometer/ad5272.txt          | 27 ++++++++++++++++++++++
 1 file changed, 27 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/iio/potentiometer/ad5272.txt

diff --git a/Documentation/devicetree/bindings/iio/potentiometer/ad5272.txt b/Documentation/devicetree/bindings/iio/potentiometer/ad5272.txt
new file mode 100644
index 0000000..dde4c67
--- /dev/null
+++ b/Documentation/devicetree/bindings/iio/potentiometer/ad5272.txt
@@ -0,0 +1,27 @@
+* Analog Devices AD5272 digital potentiometer driver
+
+The node for this driver must be a child node of a I2C controller, hence
+all mandatory properties for your controller must be specified. See directory:
+
+        Documentation/devicetree/bindings/i2c
+
+for more details.
+
+Required properties:
+	- compatible:  	Must be one of the following, depending on the model:
+			adi,ad5272-020
+			adi,ad5272-050
+			adi,ad5272-100
+			adi,ad5274-020
+			adi,ad5274-100
+
+Optional properties:
+ - reset-gpios: GPIO specification for the RESET input. This is an
+		active low signal to the PCA953x.
+
+Example:
+ad5272: ad5272@2f {
+	reg = <0x2F>;
+	compatible = "adi,ad5272-020";
+	reset-gpios = <&gpio3 6 GPIO_ACTIVE_LOW>;
+};
-- 
1.8.3.1

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[PATCH 2/2] iio: ad5272: Add support for Analog Devices digital potentiometers

[Phil Reid]

Add implementation for Analog Devices AD5272 and AD5274 digital
potentiometer devices.

Signed-off-by: Phil Reid <preid-qgqNFa1JUf/o2iN0hyhwsIdd74u8MsAO@public.gmane.org>
---
 drivers/iio/potentiometer/Kconfig  |  10 ++
 drivers/iio/potentiometer/Makefile |   1 +
 drivers/iio/potentiometer/ad5272.c | 219 +++++++++++++++++++++++++++++++++++++
 3 files changed, 230 insertions(+)
 create mode 100644 drivers/iio/potentiometer/ad5272.c

diff --git a/drivers/iio/potentiometer/Kconfig b/drivers/iio/potentiometer/Kconfig
index 8bf2825..0b04063 100644
--- a/drivers/iio/potentiometer/Kconfig
+++ b/drivers/iio/potentiometer/Kconfig
@@ -5,6 +5,16 @@
 
 menu "Digital potentiometers"
 
+config AD5272
+	tristate "Analog Devices AD5272 Digital Potentiometer driver"
+	depends on I2C
+	help
+	  Say yes here to build support for the Analog Devices AD5272
+	  digital potentiometer chip.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called ad5272.
+
 config DS1803
 	tristate "Maxim Integrated DS1803 Digital Potentiometer driver"
 	depends on I2C
diff --git a/drivers/iio/potentiometer/Makefile b/drivers/iio/potentiometer/Makefile
index 2260d40..498bbb8 100644
--- a/drivers/iio/potentiometer/Makefile
+++ b/drivers/iio/potentiometer/Makefile
@@ -3,6 +3,7 @@
 #
 
 # When adding new entries keep the list in alphabetical order
+obj-$(CONFIG_AD5272) += ad5272.o
 obj-$(CONFIG_DS1803) += ds1803.o
 obj-$(CONFIG_MAX5481) += max5481.o
 obj-$(CONFIG_MAX5487) += max5487.o
diff --git a/drivers/iio/potentiometer/ad5272.c b/drivers/iio/potentiometer/ad5272.c
new file mode 100644
index 0000000..b9208c2
--- /dev/null
+++ b/drivers/iio/potentiometer/ad5272.c
@@ -0,0 +1,219 @@
+/*
+ * Analog Devices AD5372 digital potentiometer driver
+ * Copyright (C) 2018 Phil Reid <preid-qgqNFa1JUf/o2iN0hyhwsIdd74u8MsAO@public.gmane.org>
+ *
+ * Datasheet: http://www.analog.com/media/en/technical-documentation/data-sheets/AD5272_5274.pdf
+ *
+ * DEVID	#Wipers	#Positions	Resistor Opts (kOhm)	i2c address
+ * ad5272	1	1024		20, 50, 100		01011xx
+ * ad5274	1	256		20, 100			01011xx
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published by
+ * the Free Software Foundation.
+ */
+
+#include <linux/gpio/consumer.h>
+#include <linux/i2c.h>
+#include <linux/iio/iio.h>
+#include <linux/module.h>
+
+#define  AD5272_RDAC_WR  1
+#define  AD5272_RDAC_RD  2
+#define  AD5272_CTL      7
+
+#define  AD5272_RDAC_WR_EN  BIT(1)
+
+struct ad5272_cfg {
+	int max_pos;
+	int kohms;
+	int shift;
+};
+
+enum ad5272_type {
+	AD5272_020,
+	AD5272_050,
+	AD5272_100,
+	AD5274_020,
+	AD5274_100,
+};
+
+static const struct ad5272_cfg ad5272_cfg[] = {
+	/* on-semiconductor parts */
+	[AD5272_020] = { .max_pos = 1024, .kohms = 20 },
+	[AD5272_050] = { .max_pos = 1024, .kohms = 50 },
+	[AD5272_100] = { .max_pos = 1024, .kohms = 100 },
+	[AD5274_020] = { .max_pos = 256,  .kohms = 20,  .shift = 2 },
+	[AD5274_100] = { .max_pos = 256,  .kohms = 100, .shift = 2 },
+};
+
+struct ad5272_data {
+	struct i2c_client       *client;
+	struct mutex            lock;
+	const struct ad5272_cfg *cfg;
+};
+
+static const struct iio_chan_spec ad5272_channel = {
+	.type = IIO_RESISTANCE,
+	.output = 1,
+	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
+	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),
+};
+
+static int ad5272_write(struct ad5272_data *data, int reg, int val)
+{
+	u8 buf[2];
+	int ret;
+
+	buf[0] = ((reg & 0xf) << 2) | ((val >> 8) & 0x3);
+	buf[1] = (u8)val;
+
+	mutex_lock(&data->lock);
+	ret = i2c_master_send(data->client, buf, 2);
+	mutex_unlock(&data->lock);
+	return ret < 0 ? ret : 0;
+}
+
+static int ad5272_read(struct ad5272_data *data, int reg, int *val)
+{
+	u8 buf[2];
+	int ret;
+
+	buf[0] = (reg & 0xf) << 2;
+	buf[1] = 0;
+
+	mutex_lock(&data->lock);
+	ret = i2c_master_send(data->client, buf, 2);
+	if (ret < 0)
+		goto error;
+
+	ret = i2c_master_recv(data->client, buf, 2);
+	if (ret < 0)
+		goto error;
+
+	*val = ((buf[0] & 0x3) << 8) | buf[1];
+	ret = 0;
+error:
+	mutex_unlock(&data->lock);
+	return ret;
+}
+
+static int ad5272_read_raw(struct iio_dev *indio_dev,
+			   struct iio_chan_spec const *chan,
+			   int *val, int *val2, long mask)
+{
+	struct ad5272_data *data = iio_priv(indio_dev);
+	int ret;
+
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW: {
+		ret = ad5272_read(data, AD5272_RDAC_RD, val);
+		*val = *val >> data->cfg->shift;
+		return ret ? ret : IIO_VAL_INT;
+	}
+	case IIO_CHAN_INFO_SCALE:
+		*val = 1000 * data->cfg->kohms;
+		*val2 = data->cfg->max_pos;
+		return IIO_VAL_FRACTIONAL;
+	}
+
+	return -EINVAL;
+}
+
+static int ad5272_write_raw(struct iio_dev *indio_dev,
+			    struct iio_chan_spec const *chan,
+			    int val, int val2, long mask)
+{
+	struct ad5272_data *data = iio_priv(indio_dev);
+
+	if (mask != IIO_CHAN_INFO_RAW)
+		return -EINVAL;
+
+	if (val >= data->cfg->max_pos || val < 0)
+		return -EINVAL;
+
+	val = val << data->cfg->shift;
+
+	return ad5272_write(data, AD5272_RDAC_WR, val);
+}
+
+static const struct iio_info ad5272_info = {
+	.read_raw = ad5272_read_raw,
+	.write_raw = ad5272_write_raw,
+	.driver_module = THIS_MODULE,
+};
+
+static int ad5272_probe(struct i2c_client *client,
+			const struct i2c_device_id *id)
+{
+	struct device *dev = &client->dev;
+	struct gpio_desc *reset_gpio;
+	struct iio_dev *indio_dev;
+	struct ad5272_data *data;
+	int ret;
+
+	reset_gpio = devm_gpiod_get_optional(&client->dev, "reset",
+		GPIOD_OUT_LOW);
+	if (IS_ERR(reset_gpio))
+		return PTR_ERR(reset_gpio);
+
+	indio_dev = devm_iio_device_alloc(dev, sizeof(*data));
+	if (!indio_dev)
+		return -ENOMEM;
+
+	i2c_set_clientdata(client, indio_dev);
+
+	data = iio_priv(indio_dev);
+	data->client = client;
+	mutex_init(&data->lock);
+	data->cfg = &ad5272_cfg[id->driver_data];
+
+	ret = ad5272_write(data, AD5272_CTL, AD5272_RDAC_WR_EN);
+	if (ret < 0)
+		return -ENODEV;
+
+	indio_dev->dev.parent = dev;
+	indio_dev->info = &ad5272_info;
+	indio_dev->channels = &ad5272_channel;
+	indio_dev->num_channels = 1;
+	indio_dev->name = client->name;
+
+	return devm_iio_device_register(dev, indio_dev);
+}
+
+#if defined(CONFIG_OF)
+static const struct of_device_id ad5272_dt_ids[] = {
+	{ .compatible = "adi,ad5272-020", .data = &ad5272_cfg[AD5272_020] },
+	{ .compatible = "adi,ad5272-050", .data = &ad5272_cfg[AD5272_050] },
+	{ .compatible = "adi,ad5272-100", .data = &ad5272_cfg[AD5272_100] },
+	{ .compatible = "adi,ad5274-020", .data = &ad5272_cfg[AD5274_020] },
+	{ .compatible = "adi,ad5274-100", .data = &ad5272_cfg[AD5274_100] },
+	{}
+};
+MODULE_DEVICE_TABLE(of, ad5272_dt_ids);
+#endif /* CONFIG_OF */
+
+static const struct i2c_device_id ad5272_id[] = {
+	{ "ad5272-020", AD5272_020 },
+	{ "ad5272-050", AD5272_050 },
+	{ "ad5272-100", AD5272_100 },
+	{ "ad5274-020", AD5274_020 },
+	{ "ad5274-100", AD5274_100 },
+	{}
+};
+MODULE_DEVICE_TABLE(i2c, ad5272_id);
+
+static struct i2c_driver ad5272_driver = {
+	.driver = {
+		.name	= "ad5272",
+		.of_match_table = of_match_ptr(ad5272_dt_ids),
+	},
+	.probe		= ad5272_probe,
+	.id_table	= ad5272_id,
+};
+
+module_i2c_driver(ad5272_driver);
+
+MODULE_AUTHOR("Phil Reid <preid-TeWIRZsGUAnP+dxuUfoltA@public.gmane.org>");
+MODULE_DESCRIPTION("AD5272 digital potentiometer");
+MODULE_LICENSE("GPL v2");
-- 
1.8.3.1

Re: [PATCH 2/2] iio: ad5272: Add support for Analog Devices digital potentiometers

[Phil Reid]

On 10/01/2018 14:17, Phil Reid wrote:
> Add implementation for Analog Devices AD5272 and AD5274 digital
> potentiometer devices.
> 
> Signed-off-by: Phil Reid <preid-qgqNFa1JUf/o2iN0hyhwsIdd74u8MsAO@public.gmane.org>
> ---
>   drivers/iio/potentiometer/Kconfig  |  10 ++
>   drivers/iio/potentiometer/Makefile |   1 +
>   drivers/iio/potentiometer/ad5272.c | 219 +++++++++++++++++++++++++++++++++++++
>   3 files changed, 230 insertions(+)
>   create mode 100644 drivers/iio/potentiometer/ad5272.c
> 
> diff --git a/drivers/iio/potentiometer/Kconfig b/drivers/iio/potentiometer/Kconfig
> index 8bf2825..0b04063 100644
> --- a/drivers/iio/potentiometer/Kconfig
> +++ b/drivers/iio/potentiometer/Kconfig
> @@ -5,6 +5,16 @@
>   
>   menu "Digital potentiometers"
>   
> +config AD5272
> +	tristate "Analog Devices AD5272 Digital Potentiometer driver"
> +	depends on I2C
> +	help
> +	  Say yes here to build support for the Analog Devices AD5272
> +	  digital potentiometer chip.
> +
> +	  To compile this driver as a module, choose M here: the
> +	  module will be called ad5272.
> +
>   config DS1803
>   	tristate "Maxim Integrated DS1803 Digital Potentiometer driver"
>   	depends on I2C
> diff --git a/drivers/iio/potentiometer/Makefile b/drivers/iio/potentiometer/Makefile
> index 2260d40..498bbb8 100644
> --- a/drivers/iio/potentiometer/Makefile
> +++ b/drivers/iio/potentiometer/Makefile
> @@ -3,6 +3,7 @@
>   #
>   
>   # When adding new entries keep the list in alphabetical order
> +obj-$(CONFIG_AD5272) += ad5272.o
>   obj-$(CONFIG_DS1803) += ds1803.o
>   obj-$(CONFIG_MAX5481) += max5481.o
>   obj-$(CONFIG_MAX5487) += max5487.o
> diff --git a/drivers/iio/potentiometer/ad5272.c b/drivers/iio/potentiometer/ad5272.c
> new file mode 100644
> index 0000000..b9208c2
> --- /dev/null
> +++ b/drivers/iio/potentiometer/ad5272.c
> @@ -0,0 +1,219 @@
> +/*
> + * Analog Devices AD5372 digital potentiometer driver
> + * Copyright (C) 2018 Phil Reid <preid-qgqNFa1JUf/o2iN0hyhwsIdd74u8MsAO@public.gmane.org>
> + *
> + * Datasheet: http://www.analog.com/media/en/technical-documentation/data-sheets/AD5272_5274.pdf
> + *
> + * DEVID	#Wipers	#Positions	Resistor Opts (kOhm)	i2c address
> + * ad5272	1	1024		20, 50, 100		01011xx
> + * ad5274	1	256		20, 100			01011xx
> + *
> + * This program is free software; you can redistribute it and/or modify it
> + * under the terms of the GNU General Public License version 2 as published by
> + * the Free Software Foundation.
> + */
> +
> +#include <linux/gpio/consumer.h>
> +#include <linux/i2c.h>
> +#include <linux/iio/iio.h>
> +#include <linux/module.h>
> +
> +#define  AD5272_RDAC_WR  1
> +#define  AD5272_RDAC_RD  2
> +#define  AD5272_CTL      7
> +
> +#define  AD5272_RDAC_WR_EN  BIT(1)
> +
> +struct ad5272_cfg {
> +	int max_pos;
> +	int kohms;
> +	int shift;
> +};
> +
> +enum ad5272_type {
> +	AD5272_020,
> +	AD5272_050,
> +	AD5272_100,
> +	AD5274_020,
> +	AD5274_100,
> +};
> +
> +static const struct ad5272_cfg ad5272_cfg[] = {
> +	/* on-semiconductor parts */
> +	[AD5272_020] = { .max_pos = 1024, .kohms = 20 },
> +	[AD5272_050] = { .max_pos = 1024, .kohms = 50 },
> +	[AD5272_100] = { .max_pos = 1024, .kohms = 100 },
> +	[AD5274_020] = { .max_pos = 256,  .kohms = 20,  .shift = 2 },
> +	[AD5274_100] = { .max_pos = 256,  .kohms = 100, .shift = 2 },
> +};
> +
> +struct ad5272_data {
> +	struct i2c_client       *client;
> +	struct mutex            lock;
> +	const struct ad5272_cfg *cfg;
> +};
> +
> +static const struct iio_chan_spec ad5272_channel = {
> +	.type = IIO_RESISTANCE,
> +	.output = 1,
> +	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
> +	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),
> +};
> +
> +static int ad5272_write(struct ad5272_data *data, int reg, int val)
> +{
> +	u8 buf[2];
> +	int ret;
> +
> +	buf[0] = ((reg & 0xf) << 2) | ((val >> 8) & 0x3);
> +	buf[1] = (u8)val;
> +
> +	mutex_lock(&data->lock);
> +	ret = i2c_master_send(data->client, buf, 2);
> +	mutex_unlock(&data->lock);
> +	return ret < 0 ? ret : 0;
> +}
> +
> +static int ad5272_read(struct ad5272_data *data, int reg, int *val)
> +{
> +	u8 buf[2];
> +	int ret;
> +
> +	buf[0] = (reg & 0xf) << 2;
> +	buf[1] = 0;
> +
> +	mutex_lock(&data->lock);
> +	ret = i2c_master_send(data->client, buf, 2);
> +	if (ret < 0)
> +		goto error;
> +
> +	ret = i2c_master_recv(data->client, buf, 2);
> +	if (ret < 0)
> +		goto error;
> +
> +	*val = ((buf[0] & 0x3) << 8) | buf[1];
> +	ret = 0;
> +error:
> +	mutex_unlock(&data->lock);
> +	return ret;
> +}
> +
> +static int ad5272_read_raw(struct iio_dev *indio_dev,
> +			   struct iio_chan_spec const *chan,
> +			   int *val, int *val2, long mask)
> +{
> +	struct ad5272_data *data = iio_priv(indio_dev);
> +	int ret;
> +
> +	switch (mask) {
> +	case IIO_CHAN_INFO_RAW: {
> +		ret = ad5272_read(data, AD5272_RDAC_RD, val);
> +		*val = *val >> data->cfg->shift;
> +		return ret ? ret : IIO_VAL_INT;
> +	}
> +	case IIO_CHAN_INFO_SCALE:
> +		*val = 1000 * data->cfg->kohms;
> +		*val2 = data->cfg->max_pos;
> +		return IIO_VAL_FRACTIONAL;
> +	}
> +
> +	return -EINVAL;
> +}
> +
> +static int ad5272_write_raw(struct iio_dev *indio_dev,
> +			    struct iio_chan_spec const *chan,
> +			    int val, int val2, long mask)
> +{
> +	struct ad5272_data *data = iio_priv(indio_dev);
> +
> +	if (mask != IIO_CHAN_INFO_RAW)
> +		return -EINVAL;
> +
> +	if (val >= data->cfg->max_pos || val < 0)
> +		return -EINVAL;
> +
> +	val = val << data->cfg->shift;
> +
> +	return ad5272_write(data, AD5272_RDAC_WR, val);
> +}
> +
> +static const struct iio_info ad5272_info = {
> +	.read_raw = ad5272_read_raw,
> +	.write_raw = ad5272_write_raw,
> +	.driver_module = THIS_MODULE,
> +};
> +
> +static int ad5272_probe(struct i2c_client *client,
> +			const struct i2c_device_id *id)
> +{
> +	struct device *dev = &client->dev;
> +	struct gpio_desc *reset_gpio;
> +	struct iio_dev *indio_dev;
> +	struct ad5272_data *data;
> +	int ret;
> +
> +	reset_gpio = devm_gpiod_get_optional(&client->dev, "reset",
> +		GPIOD_OUT_LOW);
Reset line to the chip is active low, so I guess I should really be setting it to GPIOD_OUT_HIGH.
Instead of having the DT define it as active-low?
I'm not sure what makes the most sense.

> +	if (IS_ERR(reset_gpio))
> +		return PTR_ERR(reset_gpio);
> +
> +	indio_dev = devm_iio_device_alloc(dev, sizeof(*data));
> +	if (!indio_dev)
> +		return -ENOMEM;
> +
> +	i2c_set_clientdata(client, indio_dev);
> +
> +	data = iio_priv(indio_dev);
> +	data->client = client;
> +	mutex_init(&data->lock);
> +	data->cfg = &ad5272_cfg[id->driver_data];
> +
> +	ret = ad5272_write(data, AD5272_CTL, AD5272_RDAC_WR_EN);
> +	if (ret < 0)
> +		return -ENODEV;
> +
> +	indio_dev->dev.parent = dev;
> +	indio_dev->info = &ad5272_info;
> +	indio_dev->channels = &ad5272_channel;
> +	indio_dev->num_channels = 1;
> +	indio_dev->name = client->name;
> +
> +	return devm_iio_device_register(dev, indio_dev);
> +}
> +
> +#if defined(CONFIG_OF)
> +static const struct of_device_id ad5272_dt_ids[] = {
> +	{ .compatible = "adi,ad5272-020", .data = &ad5272_cfg[AD5272_020] },
> +	{ .compatible = "adi,ad5272-050", .data = &ad5272_cfg[AD5272_050] },
> +	{ .compatible = "adi,ad5272-100", .data = &ad5272_cfg[AD5272_100] },
> +	{ .compatible = "adi,ad5274-020", .data = &ad5272_cfg[AD5274_020] },
> +	{ .compatible = "adi,ad5274-100", .data = &ad5272_cfg[AD5274_100] },
> +	{}
> +};
> +MODULE_DEVICE_TABLE(of, ad5272_dt_ids);
> +#endif /* CONFIG_OF */
> +
> +static const struct i2c_device_id ad5272_id[] = {
> +	{ "ad5272-020", AD5272_020 },
> +	{ "ad5272-050", AD5272_050 },
> +	{ "ad5272-100", AD5272_100 },
> +	{ "ad5274-020", AD5274_020 },
> +	{ "ad5274-100", AD5274_100 },
> +	{}
> +};
> +MODULE_DEVICE_TABLE(i2c, ad5272_id);
> +
> +static struct i2c_driver ad5272_driver = {
> +	.driver = {
> +		.name	= "ad5272",
> +		.of_match_table = of_match_ptr(ad5272_dt_ids),
> +	},
> +	.probe		= ad5272_probe,
> +	.id_table	= ad5272_id,
> +};
> +
> +module_i2c_driver(ad5272_driver);
> +
> +MODULE_AUTHOR("Phil Reid <preid-TeWIRZsGUAnP+dxuUfoltA@public.gmane.org>");
> +MODULE_DESCRIPTION("AD5272 digital potentiometer");
> +MODULE_LICENSE("GPL v2");
> 


-- 
Regards
Phil Reid

Re: [PATCH 2/2] iio: ad5272: Add support for Analog Devices digital potentiometers

[Jonathan Cameron]

On Thu, 11 Jan 2018 17:00:31 +0800
Phil Reid <preid-qgqNFa1JUf/o2iN0hyhwsIdd74u8MsAO@public.gmane.org> wrote:
...

> > +static int ad5272_probe(struct i2c_client *client,
> > +			const struct i2c_device_id *id)
> > +{
> > +	struct device *dev = &client->dev;
> > +	struct gpio_desc *reset_gpio;
> > +	struct iio_dev *indio_dev;
> > +	struct ad5272_data *data;
> > +	int ret;
> > +
> > +	reset_gpio = devm_gpiod_get_optional(&client->dev, "reset",
> > +		GPIOD_OUT_LOW);  
> Reset line to the chip is active low, so I guess I should really be setting it to GPIOD_OUT_HIGH.
> Instead of having the DT define it as active-low?
> I'm not sure what makes the most sense.

As long as you are consistent it doesn't really matter.  This flexibility is
more relevant for generic code where we might need to make things work across
both options.

Jonathan


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Re: [PATCH 2/2] iio: ad5272: Add support for Analog Devices digital potentiometers

[Jonathan Cameron]

On Wed, 10 Jan 2018 14:17:31 +0800
Phil Reid <preid-qgqNFa1JUf/o2iN0hyhwsIdd74u8MsAO@public.gmane.org> wrote:

> Add implementation for Analog Devices AD5272 and AD5274 digital
> potentiometer devices.
> 
> Signed-off-by: Phil Reid <preid-qgqNFa1JUf/o2iN0hyhwsIdd74u8MsAO@public.gmane.org>

Hi Phil,

A few minor comments inline, but looking pretty good.

Jonathan

> ---
>  drivers/iio/potentiometer/Kconfig  |  10 ++
>  drivers/iio/potentiometer/Makefile |   1 +
>  drivers/iio/potentiometer/ad5272.c | 219 +++++++++++++++++++++++++++++++++++++
>  3 files changed, 230 insertions(+)
>  create mode 100644 drivers/iio/potentiometer/ad5272.c
> 
> diff --git a/drivers/iio/potentiometer/Kconfig b/drivers/iio/potentiometer/Kconfig
> index 8bf2825..0b04063 100644
> --- a/drivers/iio/potentiometer/Kconfig
> +++ b/drivers/iio/potentiometer/Kconfig
> @@ -5,6 +5,16 @@
>  
>  menu "Digital potentiometers"
>  
> +config AD5272
> +	tristate "Analog Devices AD5272 Digital Potentiometer driver"
> +	depends on I2C
> +	help
> +	  Say yes here to build support for the Analog Devices AD5272
> +	  digital potentiometer chip.
> +
> +	  To compile this driver as a module, choose M here: the
> +	  module will be called ad5272.
> +
>  config DS1803
>  	tristate "Maxim Integrated DS1803 Digital Potentiometer driver"
>  	depends on I2C
> diff --git a/drivers/iio/potentiometer/Makefile b/drivers/iio/potentiometer/Makefile
> index 2260d40..498bbb8 100644
> --- a/drivers/iio/potentiometer/Makefile
> +++ b/drivers/iio/potentiometer/Makefile
> @@ -3,6 +3,7 @@
>  #
>  
>  # When adding new entries keep the list in alphabetical order
> +obj-$(CONFIG_AD5272) += ad5272.o
>  obj-$(CONFIG_DS1803) += ds1803.o
>  obj-$(CONFIG_MAX5481) += max5481.o
>  obj-$(CONFIG_MAX5487) += max5487.o
> diff --git a/drivers/iio/potentiometer/ad5272.c b/drivers/iio/potentiometer/ad5272.c
> new file mode 100644
> index 0000000..b9208c2
> --- /dev/null
> +++ b/drivers/iio/potentiometer/ad5272.c
> @@ -0,0 +1,219 @@
> +/*
> + * Analog Devices AD5372 digital potentiometer driver
> + * Copyright (C) 2018 Phil Reid <preid-qgqNFa1JUf/o2iN0hyhwsIdd74u8MsAO@public.gmane.org>
> + *
> + * Datasheet: http://www.analog.com/media/en/technical-documentation/data-sheets/AD5272_5274.pdf
> + *
> + * DEVID	#Wipers	#Positions	Resistor Opts (kOhm)	i2c address
> + * ad5272	1	1024		20, 50, 100		01011xx
> + * ad5274	1	256		20, 100			01011xx
> + *
> + * This program is free software; you can redistribute it and/or modify it
> + * under the terms of the GNU General Public License version 2 as published by
> + * the Free Software Foundation.

Could go all SPDX with the gpl part of this.  Personally I don't mind
much but we'll probably end up converting it over soon anyway.

> + */
> +
> +#include <linux/gpio/consumer.h>
> +#include <linux/i2c.h>
> +#include <linux/iio/iio.h>
> +#include <linux/module.h>
> +
> +#define  AD5272_RDAC_WR  1
> +#define  AD5272_RDAC_RD  2
> +#define  AD5272_CTL      7
> +
> +#define  AD5272_RDAC_WR_EN  BIT(1)
> +
> +struct ad5272_cfg {
> +	int max_pos;
> +	int kohms;
> +	int shift;
> +};
> +
> +enum ad5272_type {
> +	AD5272_020,
> +	AD5272_050,
> +	AD5272_100,
> +	AD5274_020,
> +	AD5274_100,
> +};
> +
> +static const struct ad5272_cfg ad5272_cfg[] = {
> +	/* on-semiconductor parts */
> +	[AD5272_020] = { .max_pos = 1024, .kohms = 20 },
> +	[AD5272_050] = { .max_pos = 1024, .kohms = 50 },
> +	[AD5272_100] = { .max_pos = 1024, .kohms = 100 },
> +	[AD5274_020] = { .max_pos = 256,  .kohms = 20,  .shift = 2 },
> +	[AD5274_100] = { .max_pos = 256,  .kohms = 100, .shift = 2 },
> +};
> +
> +struct ad5272_data {
> +	struct i2c_client       *client;
> +	struct mutex            lock;
> +	const struct ad5272_cfg *cfg;
> +};
> +
> +static const struct iio_chan_spec ad5272_channel = {
> +	.type = IIO_RESISTANCE,
> +	.output = 1,
> +	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
> +	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),
> +};
> +
> +static int ad5272_write(struct ad5272_data *data, int reg, int val)
> +{
> +	u8 buf[2];
> +	int ret;
> +
> +	buf[0] = ((reg & 0xf) << 2) | ((val >> 8) & 0x3);
> +	buf[1] = (u8)val;

again, could do as buf[2]  = {...};

> +
> +	mutex_lock(&data->lock);
> +	ret = i2c_master_send(data->client, buf, 2);

sizeof(buf) preferred.

> +	mutex_unlock(&data->lock);
> +	return ret < 0 ? ret : 0;
> +}
> +
> +static int ad5272_read(struct ad5272_data *data, int reg, int *val)
> +{
> +	u8 buf[2];

Could assign value here for compactness.
	u8 buf[2] = {(reg & 0xf) << 2, 0);

It's a little paranoid to mask reg given you are controlling it entirely
in the driver and anything of more than 4 bits is a bug anyway.
> +	int ret;
> +
> +	buf[0] = (reg & 0xf) << 2;
> +	buf[1] = 0;
> +
> +	mutex_lock(&data->lock);
> +	ret = i2c_master_send(data->client, buf, 2);
> +	if (ret < 0)
> +		goto error;
> +
> +	ret = i2c_master_recv(data->client, buf, 2);
> +	if (ret < 0)
> +		goto error;
> +
> +	*val = ((buf[0] & 0x3) << 8) | buf[1];
> +	ret = 0;
> +error:
> +	mutex_unlock(&data->lock);
> +	return ret;
> +}
> +
> +static int ad5272_read_raw(struct iio_dev *indio_dev,
> +			   struct iio_chan_spec const *chan,
> +			   int *val, int *val2, long mask)
> +{
> +	struct ad5272_data *data = iio_priv(indio_dev);
> +	int ret;
> +
> +	switch (mask) {
> +	case IIO_CHAN_INFO_RAW: {
> +		ret = ad5272_read(data, AD5272_RDAC_RD, val);
> +		*val = *val >> data->cfg->shift;
> +		return ret ? ret : IIO_VAL_INT;
> +	}
> +	case IIO_CHAN_INFO_SCALE:
> +		*val = 1000 * data->cfg->kohms;
> +		*val2 = data->cfg->max_pos;
> +		return IIO_VAL_FRACTIONAL;
> +	}
> +
> +	return -EINVAL;
> +}
> +
> +static int ad5272_write_raw(struct iio_dev *indio_dev,
> +			    struct iio_chan_spec const *chan,
> +			    int val, int val2, long mask)
> +{
> +	struct ad5272_data *data = iio_priv(indio_dev);
> +
> +	if (mask != IIO_CHAN_INFO_RAW)
> +		return -EINVAL;
> +
> +	if (val >= data->cfg->max_pos || val < 0)
> +		return -EINVAL;

Also verify that val2 = 0 as otherwise the classic
1.999999 evaluates to 1 rather surprises users.

> +
> +	val = val << data->cfg->shift;

I would role this into the next line.

	return ad5272_write(data, AD5272_RDAC_WR, val << data->cfg->shift);
> +
> +	return ad5272_write(data, AD5272_RDAC_WR, val);
> +}
> +
> +static const struct iio_info ad5272_info = {
> +	.read_raw = ad5272_read_raw,
> +	.write_raw = ad5272_write_raw,
> +	.driver_module = THIS_MODULE,

.driver_module no longer exists so just drop this.
We do the equivalent with some macro tricks to avoid having
to have this same line in every driver.

> +};
> +
> +static int ad5272_probe(struct i2c_client *client,
> +			const struct i2c_device_id *id)
> +{
> +	struct device *dev = &client->dev;
> +	struct gpio_desc *reset_gpio;
> +	struct iio_dev *indio_dev;
> +	struct ad5272_data *data;
> +	int ret;
> +
> +	reset_gpio = devm_gpiod_get_optional(&client->dev, "reset",
> +		GPIOD_OUT_LOW);
> +	if (IS_ERR(reset_gpio))
> +		return PTR_ERR(reset_gpio);
> +
> +	indio_dev = devm_iio_device_alloc(dev, sizeof(*data));
> +	if (!indio_dev)
> +		return -ENOMEM;
> +
> +	i2c_set_clientdata(client, indio_dev);
> +
> +	data = iio_priv(indio_dev);
> +	data->client = client;
> +	mutex_init(&data->lock);
> +	data->cfg = &ad5272_cfg[id->driver_data];

Calling it cfg kind of implies config to me whereas this is
chip type specific data.

> +
> +	ret = ad5272_write(data, AD5272_CTL, AD5272_RDAC_WR_EN);
> +	if (ret < 0)
> +		return -ENODEV;
> +
> +	indio_dev->dev.parent = dev;
> +	indio_dev->info = &ad5272_info;
> +	indio_dev->channels = &ad5272_channel;
> +	indio_dev->num_channels = 1;
> +	indio_dev->name = client->name;
> +
> +	return devm_iio_device_register(dev, indio_dev);
> +}
> +
> +#if defined(CONFIG_OF)
> +static const struct of_device_id ad5272_dt_ids[] = {
> +	{ .compatible = "adi,ad5272-020", .data = &ad5272_cfg[AD5272_020] },

Why do this rather than stash the index in the data parameter and look up later
(more consistent with the i2c_device_id table below)?

> +	{ .compatible = "adi,ad5272-050", .data = &ad5272_cfg[AD5272_050] },
> +	{ .compatible = "adi,ad5272-100", .data = &ad5272_cfg[AD5272_100] },
> +	{ .compatible = "adi,ad5274-020", .data = &ad5272_cfg[AD5274_020] },
> +	{ .compatible = "adi,ad5274-100", .data = &ad5272_cfg[AD5274_100] },
> +	{}
> +};
> +MODULE_DEVICE_TABLE(of, ad5272_dt_ids);
> +#endif /* CONFIG_OF */
> +
> +static const struct i2c_device_id ad5272_id[] = {
> +	{ "ad5272-020", AD5272_020 },
> +	{ "ad5272-050", AD5272_050 },
> +	{ "ad5272-100", AD5272_100 },
> +	{ "ad5274-020", AD5274_020 },
> +	{ "ad5274-100", AD5274_100 },
> +	{}
> +};
> +MODULE_DEVICE_TABLE(i2c, ad5272_id);
> +
> +static struct i2c_driver ad5272_driver = {
> +	.driver = {
> +		.name	= "ad5272",
> +		.of_match_table = of_match_ptr(ad5272_dt_ids),
> +	},
> +	.probe		= ad5272_probe,
> +	.id_table	= ad5272_id,
> +};
> +
> +module_i2c_driver(ad5272_driver);
> +
> +MODULE_AUTHOR("Phil Reid <preid-TeWIRZsGUAnP+dxuUfoltA@public.gmane.org>");
> +MODULE_DESCRIPTION("AD5272 digital potentiometer");
> +MODULE_LICENSE("GPL v2");

Re: [PATCH 2/2] iio: ad5272: Add support for Analog Devices digital potentiometers

[Phil Reid]

G'day Jonathan,

On 14/01/2018 21:39, Jonathan Cameron wrote:
> On Wed, 10 Jan 2018 14:17:31 +0800
> Phil Reid <preid-qgqNFa1JUf/o2iN0hyhwsIdd74u8MsAO@public.gmane.org> wrote:
> 
>> Add implementation for Analog Devices AD5272 and AD5274 digital
>> potentiometer devices.
>>
>> Signed-off-by: Phil Reid <preid-qgqNFa1JUf/o2iN0hyhwsIdd74u8MsAO@public.gmane.org>
> 
> Hi Phil,
> 
> A few minor comments inline, but looking pretty good.

Thanks for the review.

> 
> Jonathan
> 
>> ---
>>   drivers/iio/potentiometer/Kconfig  |  10 ++
>>   drivers/iio/potentiometer/Makefile |   1 +
>>   drivers/iio/potentiometer/ad5272.c | 219 +++++++++++++++++++++++++++++++++++++
>>   3 files changed, 230 insertions(+)
>>   create mode 100644 drivers/iio/potentiometer/ad5272.c
>>
>> diff --git a/drivers/iio/potentiometer/Kconfig b/drivers/iio/potentiometer/Kconfig
>> index 8bf2825..0b04063 100644
>> --- a/drivers/iio/potentiometer/Kconfig
>> +++ b/drivers/iio/potentiometer/Kconfig
>> @@ -5,6 +5,16 @@
>>   
>>   menu "Digital potentiometers"
>>   
>> +config AD5272
>> +	tristate "Analog Devices AD5272 Digital Potentiometer driver"
>> +	depends on I2C
>> +	help
>> +	  Say yes here to build support for the Analog Devices AD5272
>> +	  digital potentiometer chip.
>> +
>> +	  To compile this driver as a module, choose M here: the
>> +	  module will be called ad5272.
>> +
>>   config DS1803
>>   	tristate "Maxim Integrated DS1803 Digital Potentiometer driver"
>>   	depends on I2C
>> diff --git a/drivers/iio/potentiometer/Makefile b/drivers/iio/potentiometer/Makefile
>> index 2260d40..498bbb8 100644
>> --- a/drivers/iio/potentiometer/Makefile
>> +++ b/drivers/iio/potentiometer/Makefile
>> @@ -3,6 +3,7 @@
>>   #
>>   
>>   # When adding new entries keep the list in alphabetical order
>> +obj-$(CONFIG_AD5272) += ad5272.o
>>   obj-$(CONFIG_DS1803) += ds1803.o
>>   obj-$(CONFIG_MAX5481) += max5481.o
>>   obj-$(CONFIG_MAX5487) += max5487.o
>> diff --git a/drivers/iio/potentiometer/ad5272.c b/drivers/iio/potentiometer/ad5272.c
>> new file mode 100644
>> index 0000000..b9208c2
>> --- /dev/null
>> +++ b/drivers/iio/potentiometer/ad5272.c
>> @@ -0,0 +1,219 @@
>> +/*
>> + * Analog Devices AD5372 digital potentiometer driver
>> + * Copyright (C) 2018 Phil Reid <preid-qgqNFa1JUf/o2iN0hyhwsIdd74u8MsAO@public.gmane.org>
>> + *
>> + * Datasheet: http://www.analog.com/media/en/technical-documentation/data-sheets/AD5272_5274.pdf
>> + *
>> + * DEVID	#Wipers	#Positions	Resistor Opts (kOhm)	i2c address
>> + * ad5272	1	1024		20, 50, 100		01011xx
>> + * ad5274	1	256		20, 100			01011xx
>> + *
>> + * This program is free software; you can redistribute it and/or modify it
>> + * under the terms of the GNU General Public License version 2 as published by
>> + * the Free Software Foundation.
> 
> Could go all SPDX with the gpl part of this.  Personally I don't mind
> much but we'll probably end up converting it over soon anyway.
> 
>> + */
>> +
>> +#include <linux/gpio/consumer.h>
>> +#include <linux/i2c.h>
>> +#include <linux/iio/iio.h>
>> +#include <linux/module.h>
>> +
>> +#define  AD5272_RDAC_WR  1
>> +#define  AD5272_RDAC_RD  2
>> +#define  AD5272_CTL      7
>> +
>> +#define  AD5272_RDAC_WR_EN  BIT(1)
>> +
>> +struct ad5272_cfg {
>> +	int max_pos;
>> +	int kohms;
>> +	int shift;
>> +};
>> +
>> +enum ad5272_type {
>> +	AD5272_020,
>> +	AD5272_050,
>> +	AD5272_100,
>> +	AD5274_020,
>> +	AD5274_100,
>> +};
>> +
>> +static const struct ad5272_cfg ad5272_cfg[] = {
>> +	/* on-semiconductor parts */
>> +	[AD5272_020] = { .max_pos = 1024, .kohms = 20 },
>> +	[AD5272_050] = { .max_pos = 1024, .kohms = 50 },
>> +	[AD5272_100] = { .max_pos = 1024, .kohms = 100 },
>> +	[AD5274_020] = { .max_pos = 256,  .kohms = 20,  .shift = 2 },
>> +	[AD5274_100] = { .max_pos = 256,  .kohms = 100, .shift = 2 },
>> +};
>> +
>> +struct ad5272_data {
>> +	struct i2c_client       *client;
>> +	struct mutex            lock;
>> +	const struct ad5272_cfg *cfg;
>> +};
>> +
>> +static const struct iio_chan_spec ad5272_channel = {
>> +	.type = IIO_RESISTANCE,
>> +	.output = 1,
>> +	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
>> +	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),
>> +};
>> +
>> +static int ad5272_write(struct ad5272_data *data, int reg, int val)
>> +{
>> +	u8 buf[2];
>> +	int ret;
>> +
>> +	buf[0] = ((reg & 0xf) << 2) | ((val >> 8) & 0x3);
>> +	buf[1] = (u8)val;
> 
> again, could do as buf[2]  = {...};
ok
> 
>> +
>> +	mutex_lock(&data->lock);
>> +	ret = i2c_master_send(data->client, buf, 2);
> 
> sizeof(buf) preferred.
ok
> 
>> +	mutex_unlock(&data->lock);
>> +	return ret < 0 ? ret : 0;
>> +}
>> +
>> +static int ad5272_read(struct ad5272_data *data, int reg, int *val)
>> +{
>> +	u8 buf[2];
> 
> Could assign value here for compactness.
> 	u8 buf[2] = {(reg & 0xf) << 2, 0) >
> It's a little paranoid to mask reg given you are controlling it entirely
> in the driver and anything of more than 4 bits is a bug anyway.
ok

>> +	int ret;
>> +
>> +	buf[0] = (reg & 0xf) << 2;
>> +	buf[1] = 0;
>> +
>> +	mutex_lock(&data->lock);
>> +	ret = i2c_master_send(data->client, buf, 2);
>> +	if (ret < 0)
>> +		goto error;
>> +
>> +	ret = i2c_master_recv(data->client, buf, 2);
>> +	if (ret < 0)
>> +		goto error;
>> +
>> +	*val = ((buf[0] & 0x3) << 8) | buf[1];
>> +	ret = 0;
>> +error:
>> +	mutex_unlock(&data->lock);
>> +	return ret;
>> +}
>> +
>> +static int ad5272_read_raw(struct iio_dev *indio_dev,
>> +			   struct iio_chan_spec const *chan,
>> +			   int *val, int *val2, long mask)
>> +{
>> +	struct ad5272_data *data = iio_priv(indio_dev);
>> +	int ret;
>> +
>> +	switch (mask) {
>> +	case IIO_CHAN_INFO_RAW: {
>> +		ret = ad5272_read(data, AD5272_RDAC_RD, val);
>> +		*val = *val >> data->cfg->shift;
>> +		return ret ? ret : IIO_VAL_INT;
>> +	}
>> +	case IIO_CHAN_INFO_SCALE:
>> +		*val = 1000 * data->cfg->kohms;
>> +		*val2 = data->cfg->max_pos;
>> +		return IIO_VAL_FRACTIONAL;
>> +	}
>> +
>> +	return -EINVAL;
>> +}
>> +
>> +static int ad5272_write_raw(struct iio_dev *indio_dev,
>> +			    struct iio_chan_spec const *chan,
>> +			    int val, int val2, long mask)
>> +{
>> +	struct ad5272_data *data = iio_priv(indio_dev);
>> +
>> +	if (mask != IIO_CHAN_INFO_RAW)
>> +		return -EINVAL;
>> +
>> +	if (val >= data->cfg->max_pos || val < 0)
>> +		return -EINVAL;
> 
> Also verify that val2 = 0 as otherwise the classic
> 1.999999 evaluates to 1 rather surprises users.
yeap, that'd surprise me too.

> 
>> +
>> +	val = val << data->cfg->shift;
> 
> I would role this into the next line.
ok

> 
> 	return ad5272_write(data, AD5272_RDAC_WR, val << data->cfg->shift);
>> +
>> +	return ad5272_write(data, AD5272_RDAC_WR, val);
>> +}
>> +
>> +static const struct iio_info ad5272_info = {
>> +	.read_raw = ad5272_read_raw,
>> +	.write_raw = ad5272_write_raw,
>> +	.driver_module = THIS_MODULE,
> 
> .driver_module no longer exists so just drop this.
> We do the equivalent with some macro tricks to avoid having
> to have this same line in every driver.
ok

> 
>> +};
>> +
>> +static int ad5272_probe(struct i2c_client *client,
>> +			const struct i2c_device_id *id)
>> +{
>> +	struct device *dev = &client->dev;
>> +	struct gpio_desc *reset_gpio;
>> +	struct iio_dev *indio_dev;
>> +	struct ad5272_data *data;
>> +	int ret;
>> +
>> +	reset_gpio = devm_gpiod_get_optional(&client->dev, "reset",
>> +		GPIOD_OUT_LOW);
>> +	if (IS_ERR(reset_gpio))
>> +		return PTR_ERR(reset_gpio);
>> +
>> +	indio_dev = devm_iio_device_alloc(dev, sizeof(*data));
>> +	if (!indio_dev)
>> +		return -ENOMEM;
>> +
>> +	i2c_set_clientdata(client, indio_dev);
>> +
>> +	data = iio_priv(indio_dev);
>> +	data->client = client;
>> +	mutex_init(&data->lock);
>> +	data->cfg = &ad5272_cfg[id->driver_data];
> 
> Calling it cfg kind of implies config to me whereas this is
> chip type specific data.
I just followed what seemed to be the existing convention for the iio/potentmeters.
ds1803, mcp4531, max5481

Happy to change.

> 
>> +
>> +	ret = ad5272_write(data, AD5272_CTL, AD5272_RDAC_WR_EN);
>> +	if (ret < 0)
>> +		return -ENODEV;
>> +
>> +	indio_dev->dev.parent = dev;
>> +	indio_dev->info = &ad5272_info;
>> +	indio_dev->channels = &ad5272_channel;
>> +	indio_dev->num_channels = 1;
>> +	indio_dev->name = client->name;
>> +
>> +	return devm_iio_device_register(dev, indio_dev);
>> +}
>> +
>> +#if defined(CONFIG_OF)
>> +static const struct of_device_id ad5272_dt_ids[] = {
>> +	{ .compatible = "adi,ad5272-020", .data = &ad5272_cfg[AD5272_020] },
> 
> Why do this rather than stash the index in the data parameter and look up later
> (more consistent with the i2c_device_id table below)?

Yeah I was a bit confused by this.
I was following how the ds1803.c driver was doing things.
To be honest I don't have a good grasp of how .data works here or how it gets referenced or if it's
even used...


> 
>> +	{ .compatible = "adi,ad5272-050", .data = &ad5272_cfg[AD5272_050] },
>> +	{ .compatible = "adi,ad5272-100", .data = &ad5272_cfg[AD5272_100] },
>> +	{ .compatible = "adi,ad5274-020", .data = &ad5272_cfg[AD5274_020] },
>> +	{ .compatible = "adi,ad5274-100", .data = &ad5272_cfg[AD5274_100] },
>> +	{}
>> +};
>> +MODULE_DEVICE_TABLE(of, ad5272_dt_ids);
>> +#endif /* CONFIG_OF */
>> +
>> +static const struct i2c_device_id ad5272_id[] = {
>> +	{ "ad5272-020", AD5272_020 },
>> +	{ "ad5272-050", AD5272_050 },
>> +	{ "ad5272-100", AD5272_100 },
>> +	{ "ad5274-020", AD5274_020 },
>> +	{ "ad5274-100", AD5274_100 },
>> +	{}
>> +};
>> +MODULE_DEVICE_TABLE(i2c, ad5272_id);
>> +
>> +static struct i2c_driver ad5272_driver = {
>> +	.driver = {
>> +		.name	= "ad5272",
>> +		.of_match_table = of_match_ptr(ad5272_dt_ids),
>> +	},
>> +	.probe		= ad5272_probe,
>> +	.id_table	= ad5272_id,
>> +};
>> +
>> +module_i2c_driver(ad5272_driver);
>> +
>> +MODULE_AUTHOR("Phil Reid <preid-TeWIRZsGUAnP+dxuUfoltA@public.gmane.org>");
>> +MODULE_DESCRIPTION("AD5272 digital potentiometer");
>> +MODULE_LICENSE("GPL v2");
> 
> 
> 


-- 
Regards
Phil Reid

Re: [PATCH 2/2] iio: ad5272: Add support for Analog Devices digital potentiometers

[Jonathan Cameron]

On Mon, 15 Jan 2018 16:47:35 +0800
Phil Reid <preid-qgqNFa1JUf/o2iN0hyhwsIdd74u8MsAO@public.gmane.org> wrote:

> G'day Jonathan,
> 
> On 14/01/2018 21:39, Jonathan Cameron wrote:
> > On Wed, 10 Jan 2018 14:17:31 +0800
> > Phil Reid <preid-qgqNFa1JUf/o2iN0hyhwsIdd74u8MsAO@public.gmane.org> wrote:
> >   
> >> Add implementation for Analog Devices AD5272 and AD5274 digital
> >> potentiometer devices.
> >>
> >> Signed-off-by: Phil Reid <preid-qgqNFa1JUf/o2iN0hyhwsIdd74u8MsAO@public.gmane.org>  
> > 
> > Hi Phil,
> > 
> > A few minor comments inline, but looking pretty good.  
> 
> Thanks for the review.
> 
> > 
> > Jonathan
> >   
> >> ---
> >>   drivers/iio/potentiometer/Kconfig  |  10 ++
> >>   drivers/iio/potentiometer/Makefile |   1 +
> >>   drivers/iio/potentiometer/ad5272.c | 219 +++++++++++++++++++++++++++++++++++++
> >>   3 files changed, 230 insertions(+)
> >>   create mode 100644 drivers/iio/potentiometer/ad5272.c
> >>
> >> diff --git a/drivers/iio/potentiometer/Kconfig b/drivers/iio/potentiometer/Kconfig
> >> index 8bf2825..0b04063 100644
> >> --- a/drivers/iio/potentiometer/Kconfig
> >> +++ b/drivers/iio/potentiometer/Kconfig
> >> @@ -5,6 +5,16 @@
> >>   
> >>   menu "Digital potentiometers"
> >>   
> >> +config AD5272
> >> +	tristate "Analog Devices AD5272 Digital Potentiometer driver"
> >> +	depends on I2C
> >> +	help
> >> +	  Say yes here to build support for the Analog Devices AD5272
> >> +	  digital potentiometer chip.
> >> +
> >> +	  To compile this driver as a module, choose M here: the
> >> +	  module will be called ad5272.
> >> +
> >>   config DS1803
> >>   	tristate "Maxim Integrated DS1803 Digital Potentiometer driver"
> >>   	depends on I2C
> >> diff --git a/drivers/iio/potentiometer/Makefile b/drivers/iio/potentiometer/Makefile
> >> index 2260d40..498bbb8 100644
> >> --- a/drivers/iio/potentiometer/Makefile
> >> +++ b/drivers/iio/potentiometer/Makefile
> >> @@ -3,6 +3,7 @@
> >>   #
> >>   
> >>   # When adding new entries keep the list in alphabetical order
> >> +obj-$(CONFIG_AD5272) += ad5272.o
> >>   obj-$(CONFIG_DS1803) += ds1803.o
> >>   obj-$(CONFIG_MAX5481) += max5481.o
> >>   obj-$(CONFIG_MAX5487) += max5487.o
> >> diff --git a/drivers/iio/potentiometer/ad5272.c b/drivers/iio/potentiometer/ad5272.c
> >> new file mode 100644
> >> index 0000000..b9208c2
> >> --- /dev/null
> >> +++ b/drivers/iio/potentiometer/ad5272.c
> >> @@ -0,0 +1,219 @@
> >> +/*
> >> + * Analog Devices AD5372 digital potentiometer driver
> >> + * Copyright (C) 2018 Phil Reid <preid-qgqNFa1JUf/o2iN0hyhwsIdd74u8MsAO@public.gmane.org>
> >> + *
> >> + * Datasheet: http://www.analog.com/media/en/technical-documentation/data-sheets/AD5272_5274.pdf
> >> + *
> >> + * DEVID	#Wipers	#Positions	Resistor Opts (kOhm)	i2c address
> >> + * ad5272	1	1024		20, 50, 100		01011xx
> >> + * ad5274	1	256		20, 100			01011xx
> >> + *
> >> + * This program is free software; you can redistribute it and/or modify it
> >> + * under the terms of the GNU General Public License version 2 as published by
> >> + * the Free Software Foundation.  
> > 
> > Could go all SPDX with the gpl part of this.  Personally I don't mind
> > much but we'll probably end up converting it over soon anyway.
> >   
> >> + */
> >> +
> >> +#include <linux/gpio/consumer.h>
> >> +#include <linux/i2c.h>
> >> +#include <linux/iio/iio.h>
> >> +#include <linux/module.h>
> >> +
> >> +#define  AD5272_RDAC_WR  1
> >> +#define  AD5272_RDAC_RD  2
> >> +#define  AD5272_CTL      7
> >> +
> >> +#define  AD5272_RDAC_WR_EN  BIT(1)
> >> +
> >> +struct ad5272_cfg {
> >> +	int max_pos;
> >> +	int kohms;
> >> +	int shift;
> >> +};
> >> +
> >> +enum ad5272_type {
> >> +	AD5272_020,
> >> +	AD5272_050,
> >> +	AD5272_100,
> >> +	AD5274_020,
> >> +	AD5274_100,
> >> +};
> >> +
> >> +static const struct ad5272_cfg ad5272_cfg[] = {
> >> +	/* on-semiconductor parts */
> >> +	[AD5272_020] = { .max_pos = 1024, .kohms = 20 },
> >> +	[AD5272_050] = { .max_pos = 1024, .kohms = 50 },
> >> +	[AD5272_100] = { .max_pos = 1024, .kohms = 100 },
> >> +	[AD5274_020] = { .max_pos = 256,  .kohms = 20,  .shift = 2 },
> >> +	[AD5274_100] = { .max_pos = 256,  .kohms = 100, .shift = 2 },
> >> +};
> >> +
> >> +struct ad5272_data {
> >> +	struct i2c_client       *client;
> >> +	struct mutex            lock;
> >> +	const struct ad5272_cfg *cfg;
> >> +};
> >> +
> >> +static const struct iio_chan_spec ad5272_channel = {
> >> +	.type = IIO_RESISTANCE,
> >> +	.output = 1,
> >> +	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
> >> +	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),
> >> +};
> >> +
> >> +static int ad5272_write(struct ad5272_data *data, int reg, int val)
> >> +{
> >> +	u8 buf[2];
> >> +	int ret;
> >> +
> >> +	buf[0] = ((reg & 0xf) << 2) | ((val >> 8) & 0x3);
> >> +	buf[1] = (u8)val;  
> > 
> > again, could do as buf[2]  = {...};  
> ok
> >   
> >> +
> >> +	mutex_lock(&data->lock);
> >> +	ret = i2c_master_send(data->client, buf, 2);  
> > 
> > sizeof(buf) preferred.  
> ok
> >   
> >> +	mutex_unlock(&data->lock);
> >> +	return ret < 0 ? ret : 0;
> >> +}
> >> +
> >> +static int ad5272_read(struct ad5272_data *data, int reg, int *val)
> >> +{
> >> +	u8 buf[2];  
> > 
> > Could assign value here for compactness.
> > 	u8 buf[2] = {(reg & 0xf) << 2, 0) >
> > It's a little paranoid to mask reg given you are controlling it entirely
> > in the driver and anything of more than 4 bits is a bug anyway.  
> ok
> 
> >> +	int ret;
> >> +
> >> +	buf[0] = (reg & 0xf) << 2;
> >> +	buf[1] = 0;
> >> +
> >> +	mutex_lock(&data->lock);
> >> +	ret = i2c_master_send(data->client, buf, 2);
> >> +	if (ret < 0)
> >> +		goto error;
> >> +
> >> +	ret = i2c_master_recv(data->client, buf, 2);
> >> +	if (ret < 0)
> >> +		goto error;
> >> +
> >> +	*val = ((buf[0] & 0x3) << 8) | buf[1];
> >> +	ret = 0;
> >> +error:
> >> +	mutex_unlock(&data->lock);
> >> +	return ret;
> >> +}
> >> +
> >> +static int ad5272_read_raw(struct iio_dev *indio_dev,
> >> +			   struct iio_chan_spec const *chan,
> >> +			   int *val, int *val2, long mask)
> >> +{
> >> +	struct ad5272_data *data = iio_priv(indio_dev);
> >> +	int ret;
> >> +
> >> +	switch (mask) {
> >> +	case IIO_CHAN_INFO_RAW: {
> >> +		ret = ad5272_read(data, AD5272_RDAC_RD, val);
> >> +		*val = *val >> data->cfg->shift;
> >> +		return ret ? ret : IIO_VAL_INT;
> >> +	}
> >> +	case IIO_CHAN_INFO_SCALE:
> >> +		*val = 1000 * data->cfg->kohms;
> >> +		*val2 = data->cfg->max_pos;
> >> +		return IIO_VAL_FRACTIONAL;
> >> +	}
> >> +
> >> +	return -EINVAL;
> >> +}
> >> +
> >> +static int ad5272_write_raw(struct iio_dev *indio_dev,
> >> +			    struct iio_chan_spec const *chan,
> >> +			    int val, int val2, long mask)
> >> +{
> >> +	struct ad5272_data *data = iio_priv(indio_dev);
> >> +
> >> +	if (mask != IIO_CHAN_INFO_RAW)
> >> +		return -EINVAL;
> >> +
> >> +	if (val >= data->cfg->max_pos || val < 0)
> >> +		return -EINVAL;  
> > 
> > Also verify that val2 = 0 as otherwise the classic
> > 1.999999 evaluates to 1 rather surprises users.  
> yeap, that'd surprise me too.
> 
> >   
> >> +
> >> +	val = val << data->cfg->shift;  
> > 
> > I would role this into the next line.  
> ok
> 
> > 
> > 	return ad5272_write(data, AD5272_RDAC_WR, val << data->cfg->shift);  
> >> +
> >> +	return ad5272_write(data, AD5272_RDAC_WR, val);
> >> +}
> >> +
> >> +static const struct iio_info ad5272_info = {
> >> +	.read_raw = ad5272_read_raw,
> >> +	.write_raw = ad5272_write_raw,
> >> +	.driver_module = THIS_MODULE,  
> > 
> > .driver_module no longer exists so just drop this.
> > We do the equivalent with some macro tricks to avoid having
> > to have this same line in every driver.  
> ok
> 
> >   
> >> +};
> >> +
> >> +static int ad5272_probe(struct i2c_client *client,
> >> +			const struct i2c_device_id *id)
> >> +{
> >> +	struct device *dev = &client->dev;
> >> +	struct gpio_desc *reset_gpio;
> >> +	struct iio_dev *indio_dev;
> >> +	struct ad5272_data *data;
> >> +	int ret;
> >> +
> >> +	reset_gpio = devm_gpiod_get_optional(&client->dev, "reset",
> >> +		GPIOD_OUT_LOW);
> >> +	if (IS_ERR(reset_gpio))
> >> +		return PTR_ERR(reset_gpio);
> >> +
> >> +	indio_dev = devm_iio_device_alloc(dev, sizeof(*data));
> >> +	if (!indio_dev)
> >> +		return -ENOMEM;
> >> +
> >> +	i2c_set_clientdata(client, indio_dev);
> >> +
> >> +	data = iio_priv(indio_dev);
> >> +	data->client = client;
> >> +	mutex_init(&data->lock);
> >> +	data->cfg = &ad5272_cfg[id->driver_data];  
> > 
> > Calling it cfg kind of implies config to me whereas this is
> > chip type specific data.  
> I just followed what seemed to be the existing convention for the iio/potentmeters.
> ds1803, mcp4531, max5481
> 
> Happy to change.
> 
> >   
> >> +
> >> +	ret = ad5272_write(data, AD5272_CTL, AD5272_RDAC_WR_EN);
> >> +	if (ret < 0)
> >> +		return -ENODEV;
> >> +
> >> +	indio_dev->dev.parent = dev;
> >> +	indio_dev->info = &ad5272_info;
> >> +	indio_dev->channels = &ad5272_channel;
> >> +	indio_dev->num_channels = 1;
> >> +	indio_dev->name = client->name;
> >> +
> >> +	return devm_iio_device_register(dev, indio_dev);
> >> +}
> >> +
> >> +#if defined(CONFIG_OF)
> >> +static const struct of_device_id ad5272_dt_ids[] = {
> >> +	{ .compatible = "adi,ad5272-020", .data = &ad5272_cfg[AD5272_020] },  
> > 
> > Why do this rather than stash the index in the data parameter and look up later
> > (more consistent with the i2c_device_id table below)?  
> 
> Yeah I was a bit confused by this.
> I was following how the ds1803.c driver was doing things.
> To be honest I don't have a good grasp of how .data works here or how it gets referenced or if it's
> even used...
Good point - you aren't currently using it.

This gets more interesting when i2c actually starts using the
of tables for devicetree rather than the older i2c_device_id tables.

The .data field is used for the same purpose as the indexes in
the other table, but you have to explicitly request it
with of_get_match_data

Jonathan
> 
> 
> >   
> >> +	{ .compatible = "adi,ad5272-050", .data = &ad5272_cfg[AD5272_050] },
> >> +	{ .compatible = "adi,ad5272-100", .data = &ad5272_cfg[AD5272_100] },
> >> +	{ .compatible = "adi,ad5274-020", .data = &ad5272_cfg[AD5274_020] },
> >> +	{ .compatible = "adi,ad5274-100", .data = &ad5272_cfg[AD5274_100] },
> >> +	{}
> >> +};
> >> +MODULE_DEVICE_TABLE(of, ad5272_dt_ids);
> >> +#endif /* CONFIG_OF */
> >> +
> >> +static const struct i2c_device_id ad5272_id[] = {
> >> +	{ "ad5272-020", AD5272_020 },
> >> +	{ "ad5272-050", AD5272_050 },
> >> +	{ "ad5272-100", AD5272_100 },
> >> +	{ "ad5274-020", AD5274_020 },
> >> +	{ "ad5274-100", AD5274_100 },
> >> +	{}
> >> +};
> >> +MODULE_DEVICE_TABLE(i2c, ad5272_id);
> >> +
> >> +static struct i2c_driver ad5272_driver = {
> >> +	.driver = {
> >> +		.name	= "ad5272",
> >> +		.of_match_table = of_match_ptr(ad5272_dt_ids),
> >> +	},
> >> +	.probe		= ad5272_probe,
> >> +	.id_table	= ad5272_id,
> >> +};
> >> +
> >> +module_i2c_driver(ad5272_driver);
> >> +
> >> +MODULE_AUTHOR("Phil Reid <preid-TeWIRZsGUAnP+dxuUfoltA@public.gmane.org>");
> >> +MODULE_DESCRIPTION("AD5272 digital potentiometer");
> >> +MODULE_LICENSE("GPL v2");  
> > 
> > 
> >   
> 
> 

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