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[PATCH 1/3] iio: adc: add ltc2309 support

Liam Beguin posted 3 patches 2 years, 3 months ago
There is a newer version of this series
[PATCH 1/3] iio: adc: add ltc2309 support
Posted by Liam Beguin 2 years, 3 months ago 
The LTC2309 is an 8-Channel, 12-Bit SAR ADC with an I2C Interface.

This implements support for all single-ended and differential channels,
in unipolar mode only.

Signed-off-by: Liam Beguin <liambeguin@gmail.com>
---
 drivers/iio/adc/Kconfig   |  10 ++
 drivers/iio/adc/Makefile  |   1 +
 drivers/iio/adc/ltc2309.c | 232 ++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 243 insertions(+)

diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
index dc14bde31ac1..6ec18e02faf9 100644
--- a/drivers/iio/adc/Kconfig
+++ b/drivers/iio/adc/Kconfig
@@ -607,6 +607,16 @@ config LPC32XX_ADC
 	  activate only one via device tree selection.  Provides direct access
 	  via sysfs.
 
+config LTC2309
+	tristate "Linear Technology LTC2309 ADC driver"
+	depends on I2C
+	help
+	  Say yes here to build support for Linear Technology LTC2309, a low
+	  noise, low power, 8-channel, 12-bit SAR ADC
+
+	  This driver can also be built as a module. If so, the module will
+	  be called ltc2309.
+
 config LTC2471
 	tristate "Linear Technology LTC2471 and LTC2473 ADC driver"
 	depends on I2C
diff --git a/drivers/iio/adc/Makefile b/drivers/iio/adc/Makefile
index eb6e891790fb..fbd86184ec94 100644
--- a/drivers/iio/adc/Makefile
+++ b/drivers/iio/adc/Makefile
@@ -56,6 +56,7 @@ obj-$(CONFIG_INTEL_MRFLD_ADC) += intel_mrfld_adc.o
 obj-$(CONFIG_LP8788_ADC) += lp8788_adc.o
 obj-$(CONFIG_LPC18XX_ADC) += lpc18xx_adc.o
 obj-$(CONFIG_LPC32XX_ADC) += lpc32xx_adc.o
+obj-$(CONFIG_LTC2309) += ltc2309.o
 obj-$(CONFIG_LTC2471) += ltc2471.o
 obj-$(CONFIG_LTC2485) += ltc2485.o
 obj-$(CONFIG_LTC2496) += ltc2496.o ltc2497-core.o
diff --git a/drivers/iio/adc/ltc2309.c b/drivers/iio/adc/ltc2309.c
new file mode 100644
index 000000000000..ee1fd9b82e2a
--- /dev/null
+++ b/drivers/iio/adc/ltc2309.c
@@ -0,0 +1,232 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * The LTC2309 is an 8-Channel, 12-Bit SAR ADC with an I2C Interface.
+ *
+ * Datasheet:
+ * https://www.analog.com/media/en/technical-documentation/data-sheets/2309fd.pdf
+ *
+ * Copyright (c) 2023, Liam Beguin <liambeguin@gmail.com>
+ *
+ */
+#include <linux/bitfield.h>
+#include <linux/i2c.h>
+#include <linux/iio/iio.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/regulator/consumer.h>
+
+#define DRIVER_NAME		"ltc2309"
+#define LTC2309_ADC_RESOLUTION	12
+
+#define LTC2309_DIN_CH_MASK	GENMASK(7, 4)
+#define LTC2309_DIN_SDN		BIT(7)
+#define LTC2309_DIN_OSN		BIT(6)
+#define LTC2309_DIN_S1		BIT(5)
+#define LTC2309_DIN_S0		BIT(4)
+#define LTC2309_DIN_UNI		BIT(3)
+#define LTC2309_DIN_SLEEP	BIT(2)
+
+/* struct ltc2309 - internal device data structure
+ *
+ * @dev:	Device reference
+ * @client:	I2C reference
+ * @refcomp:	External reference source
+ * @lock:	Lock to protect against multiple access to the device
+ * @vref_mv	Internal voltage reference
+ */
+struct ltc2309 {
+	struct device		*dev;
+	struct i2c_client	*client;
+	struct regulator	*refcomp;
+	struct mutex		lock;
+	int			vref_mv;
+};
+
+/* Order matches expected channel address, See datasheet Table 1. */
+enum ltc2309_channels {
+	LTC2309_CH0_CH1 = 0,
+	LTC2309_CH2_CH3,
+	LTC2309_CH4_CH5,
+	LTC2309_CH6_CH7,
+	LTC2309_CH1_CH0,
+	LTC2309_CH3_CH2,
+	LTC2309_CH5_CH4,
+	LTC2309_CH7_CH6,
+	LTC2309_CH0,
+	LTC2309_CH2,
+	LTC2309_CH4,
+	LTC2309_CH6,
+	LTC2309_CH1,
+	LTC2309_CH3,
+	LTC2309_CH5,
+	LTC2309_CH7,
+};
+
+#define LTC2309_CHAN(_chan, _addr) {				\
+	.type = IIO_VOLTAGE,					\
+	.indexed = 1,						\
+	.address = _addr,					\
+	.channel = _chan,					\
+	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),		\
+	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),	\
+	.datasheet_name = "CH"#_chan,				\
+}
+
+#define LTC2309_DIFF_CHAN(_chan, _chan2, _addr) {		\
+	.type = IIO_VOLTAGE,					\
+	.differential = 1,					\
+	.indexed = 1,						\
+	.address = _addr,					\
+	.channel = _chan,					\
+	.channel2 = _chan2,					\
+	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),		\
+	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),	\
+	.datasheet_name = "CH"#_chan"-CH"#_chan2,		\
+}
+
+static const struct iio_chan_spec ltc2309_channels[] = {
+	LTC2309_CHAN(0, LTC2309_CH0),
+	LTC2309_CHAN(1, LTC2309_CH1),
+	LTC2309_CHAN(2, LTC2309_CH2),
+	LTC2309_CHAN(3, LTC2309_CH3),
+	LTC2309_CHAN(4, LTC2309_CH4),
+	LTC2309_CHAN(5, LTC2309_CH5),
+	LTC2309_CHAN(6, LTC2309_CH6),
+	LTC2309_CHAN(7, LTC2309_CH7),
+	LTC2309_DIFF_CHAN(0, 1, LTC2309_CH0_CH1),
+	LTC2309_DIFF_CHAN(2, 3, LTC2309_CH2_CH3),
+	LTC2309_DIFF_CHAN(4, 5, LTC2309_CH4_CH5),
+	LTC2309_DIFF_CHAN(6, 7, LTC2309_CH6_CH7),
+	LTC2309_DIFF_CHAN(1, 0, LTC2309_CH1_CH0),
+	LTC2309_DIFF_CHAN(3, 2, LTC2309_CH3_CH2),
+	LTC2309_DIFF_CHAN(5, 4, LTC2309_CH5_CH4),
+	LTC2309_DIFF_CHAN(7, 6, LTC2309_CH7_CH6),
+};
+
+static int ltc2309_read_raw(struct iio_dev *indio_dev,
+			    struct iio_chan_spec const *chan, int *val,
+			    int *val2, long mask)
+{
+	struct ltc2309 *ltc2309 = iio_priv(indio_dev);
+	u16 buf;
+	int ret;
+	u8 din;
+
+	mutex_lock(&ltc2309->lock);
+
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW:
+		din = FIELD_PREP(LTC2309_DIN_CH_MASK, chan->address & 0x0f) |
+			FIELD_PREP(LTC2309_DIN_UNI, 1) |
+			FIELD_PREP(LTC2309_DIN_SLEEP, 0);
+
+		ret = i2c_smbus_write_byte(ltc2309->client, din);
+		if (ret < 0) {
+			dev_err(ltc2309->dev, "i2c command failed: %pe\n",
+				ERR_PTR(ret));
+			goto out;
+		}
+
+		ret = i2c_master_recv(ltc2309->client, (char *)&buf, 2);
+		if (ret < 0) {
+			dev_err(ltc2309->dev, "i2c read failed: %pe\n",
+				ERR_PTR(ret));
+			goto out;
+		}
+
+		*val = be16_to_cpu(buf) >> 4;
+
+		ret = IIO_VAL_INT;
+		break;
+	case IIO_CHAN_INFO_SCALE:
+		*val = ltc2309->vref_mv;
+		*val2 = LTC2309_ADC_RESOLUTION;
+		ret = IIO_VAL_FRACTIONAL_LOG2;
+		break;
+	default:
+		ret = -EINVAL;
+		break;
+	}
+
+out:
+	mutex_unlock(&ltc2309->lock);
+	return ret;
+}
+
+static const struct iio_info ltc2309_info = {
+	.read_raw = ltc2309_read_raw,
+};
+
+static int ltc2309_probe(struct i2c_client *client,
+			 const struct i2c_device_id *id)
+{
+	struct iio_dev *indio_dev;
+	struct ltc2309 *ltc2309;
+	int ret = 0;
+
+	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*ltc2309));
+	if (!indio_dev)
+		return -ENOMEM;
+
+	i2c_set_clientdata(client, indio_dev);
+
+	ltc2309 = iio_priv(indio_dev);
+	ltc2309->dev = &indio_dev->dev;
+	ltc2309->client = client;
+	ltc2309->vref_mv = 4096; /* Default to the internal ref */
+
+	indio_dev->name = DRIVER_NAME;
+	indio_dev->dev.parent = &client->dev;
+	indio_dev->modes = INDIO_DIRECT_MODE;
+	indio_dev->channels = ltc2309_channels;
+	indio_dev->num_channels = ARRAY_SIZE(ltc2309_channels);
+	indio_dev->info = &ltc2309_info;
+
+	ltc2309->refcomp = devm_regulator_get_optional(&client->dev, "refcomp");
+	if (!IS_ERR_OR_NULL(ltc2309->refcomp)) {
+		ret = regulator_enable(ltc2309->refcomp);
+		if (ret) {
+			dev_err(ltc2309->dev, "failed to enable REFCOMP\n");
+			return ret;
+		}
+
+		ret = regulator_get_voltage(ltc2309->refcomp);
+		if (ret < 0)
+			return ret;
+
+		ltc2309->vref_mv = ret / 1000;
+		if (ret)
+			return ret;
+	}
+
+	mutex_init(&ltc2309->lock);
+
+	return devm_iio_device_register(&client->dev, indio_dev);
+}
+
+static const struct of_device_id ltc2309_of_match[] = {
+	{ .compatible = "lltc,ltc2309" },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, ltc2309_of_match);
+
+static const struct i2c_device_id ltc2309_id[] = {
+	{"ltc2309", 0},
+	{},
+};
+MODULE_DEVICE_TABLE(i2c, ltc2309_id);
+
+static struct i2c_driver ltc2309_driver = {
+	.driver = {
+		.name = DRIVER_NAME,
+		.of_match_table = ltc2309_of_match,
+	},
+	.probe		= ltc2309_probe,
+	.id_table	= ltc2309_id,
+};
+module_i2c_driver(ltc2309_driver);
+
+MODULE_AUTHOR("Liam Beguin <liambeguin@gmail.com>");
+MODULE_DESCRIPTION("Linear Technology LTC2309 ADC");
+MODULE_LICENSE("GPL v2");

-- 
2.39.0
Re: [PATCH 1/3] iio: adc: add ltc2309 support
Posted by Krzysztof Kozlowski 2 years, 3 months ago 
On 24/08/2023 18:55, Liam Beguin wrote:
> The LTC2309 is an 8-Channel, 12-Bit SAR ADC with an I2C Interface.
> 
> This implements support for all single-ended and differential channels,
> in unipolar mode only.
> 
> Signed-off-by: Liam Beguin <liambeguin@gmail.com>
> ---
>  drivers/iio/adc/Kconfig   |  10 ++
>  drivers/iio/adc/Makefile  |   1 +
>  drivers/iio/adc/ltc2309.c | 232 ++++++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 243 insertions(+)
> 



> +static int ltc2309_read_raw(struct iio_dev *indio_dev,
> +			    struct iio_chan_spec const *chan, int *val,
> +			    int *val2, long mask)
> +{
> +	struct ltc2309 *ltc2309 = iio_priv(indio_dev);
> +	u16 buf;
> +	int ret;
> +	u8 din;
> +
> +	mutex_lock(&ltc2309->lock);
> +
> +	switch (mask) {
> +	case IIO_CHAN_INFO_RAW:
> +		din = FIELD_PREP(LTC2309_DIN_CH_MASK, chan->address & 0x0f) |
> +			FIELD_PREP(LTC2309_DIN_UNI, 1) |
> +			FIELD_PREP(LTC2309_DIN_SLEEP, 0);
> +
> +		ret = i2c_smbus_write_byte(ltc2309->client, din);
> +		if (ret < 0) {
> +			dev_err(ltc2309->dev, "i2c command failed: %pe\n",
> +				ERR_PTR(ret));
> +			goto out;
> +		}
> +
> +		ret = i2c_master_recv(ltc2309->client, (char *)&buf, 2);
> +		if (ret < 0) {
> +			dev_err(ltc2309->dev, "i2c read failed: %pe\n",
> +				ERR_PTR(ret));
> +			goto out;
> +		}
> +
> +		*val = be16_to_cpu(buf) >> 4;
> +
> +		ret = IIO_VAL_INT;
> +		break;
> +	case IIO_CHAN_INFO_SCALE:
> +		*val = ltc2309->vref_mv;
> +		*val2 = LTC2309_ADC_RESOLUTION;
> +		ret = IIO_VAL_FRACTIONAL_LOG2;

Why this case is in critical section?

> +		break;
> +	default:
> +		ret = -EINVAL;
> +		break;
> +	}
> +
> +out:
> +	mutex_unlock(&ltc2309->lock);
> +	return ret;
> +}
> +
> +static const struct iio_info ltc2309_info = {
> +	.read_raw = ltc2309_read_raw,
> +};
> +
> +static int ltc2309_probe(struct i2c_client *client,
> +			 const struct i2c_device_id *id)
> +{
> +	struct iio_dev *indio_dev;
> +	struct ltc2309 *ltc2309;
> +	int ret = 0;
> +
> +	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*ltc2309));
> +	if (!indio_dev)
> +		return -ENOMEM;
> +
> +	i2c_set_clientdata(client, indio_dev);
> +
> +	ltc2309 = iio_priv(indio_dev);
> +	ltc2309->dev = &indio_dev->dev;
> +	ltc2309->client = client;
> +	ltc2309->vref_mv = 4096; /* Default to the internal ref */
> +
> +	indio_dev->name = DRIVER_NAME;
> +	indio_dev->dev.parent = &client->dev;
> +	indio_dev->modes = INDIO_DIRECT_MODE;
> +	indio_dev->channels = ltc2309_channels;
> +	indio_dev->num_channels = ARRAY_SIZE(ltc2309_channels);
> +	indio_dev->info = &ltc2309_info;
> +
> +	ltc2309->refcomp = devm_regulator_get_optional(&client->dev, "refcomp");
> +	if (!IS_ERR_OR_NULL(ltc2309->refcomp)) {
> +		ret = regulator_enable(ltc2309->refcomp);
> +		if (ret) {
> +			dev_err(ltc2309->dev, "failed to enable REFCOMP\n");
> +			return ret;
> +		}
> +
> +		ret = regulator_get_voltage(ltc2309->refcomp);
> +		if (ret < 0)

You have unbalanced regulator. Same in all further error paths.

> +			return ret;
> +
> +		ltc2309->vref_mv = ret / 1000;
> +		if (ret)
> +			return ret;
> +	}
> +
> +	mutex_init(&ltc2309->lock);
> +
> +	return devm_iio_device_register(&client->dev, indio_dev);
> +}
> +


Best regards,
Krzysztof
Re: [PATCH 1/3] iio: adc: add ltc2309 support
Posted by Liam Beguin 2 years, 3 months ago 
On Thu, Aug 24, 2023 at 08:00:11PM +0200, Krzysztof Kozlowski wrote:
> On 24/08/2023 18:55, Liam Beguin wrote:
> > The LTC2309 is an 8-Channel, 12-Bit SAR ADC with an I2C Interface.
> > 
> > This implements support for all single-ended and differential channels,
> > in unipolar mode only.
> > 
> > Signed-off-by: Liam Beguin <liambeguin@gmail.com>
> > ---
> >  drivers/iio/adc/Kconfig   |  10 ++
> >  drivers/iio/adc/Makefile  |   1 +
> >  drivers/iio/adc/ltc2309.c | 232 ++++++++++++++++++++++++++++++++++++++++++++++
> >  3 files changed, 243 insertions(+)
> > 
> 
> 
> 
> > +static int ltc2309_read_raw(struct iio_dev *indio_dev,
> > +			    struct iio_chan_spec const *chan, int *val,
> > +			    int *val2, long mask)
> > +{
> > +	struct ltc2309 *ltc2309 = iio_priv(indio_dev);
> > +	u16 buf;
> > +	int ret;
> > +	u8 din;
> > +
> > +	mutex_lock(&ltc2309->lock);
> > +
> > +	switch (mask) {
> > +	case IIO_CHAN_INFO_RAW:
> > +		din = FIELD_PREP(LTC2309_DIN_CH_MASK, chan->address & 0x0f) |
> > +			FIELD_PREP(LTC2309_DIN_UNI, 1) |
> > +			FIELD_PREP(LTC2309_DIN_SLEEP, 0);
> > +
> > +		ret = i2c_smbus_write_byte(ltc2309->client, din);
> > +		if (ret < 0) {
> > +			dev_err(ltc2309->dev, "i2c command failed: %pe\n",
> > +				ERR_PTR(ret));
> > +			goto out;
> > +		}
> > +
> > +		ret = i2c_master_recv(ltc2309->client, (char *)&buf, 2);
> > +		if (ret < 0) {
> > +			dev_err(ltc2309->dev, "i2c read failed: %pe\n",
> > +				ERR_PTR(ret));
> > +			goto out;
> > +		}
> > +
> > +		*val = be16_to_cpu(buf) >> 4;
> > +
> > +		ret = IIO_VAL_INT;
> > +		break;
> > +	case IIO_CHAN_INFO_SCALE:
> > +		*val = ltc2309->vref_mv;
> > +		*val2 = LTC2309_ADC_RESOLUTION;
> > +		ret = IIO_VAL_FRACTIONAL_LOG2;
> 
> Why this case is in critical section?
> 

my bad, I'll reduce it to INFO_RAW.

> > +		break;
> > +	default:
> > +		ret = -EINVAL;
> > +		break;
> > +	}
> > +
> > +out:
> > +	mutex_unlock(&ltc2309->lock);
> > +	return ret;
> > +}
> > +
> > +static const struct iio_info ltc2309_info = {
> > +	.read_raw = ltc2309_read_raw,
> > +};
> > +
> > +static int ltc2309_probe(struct i2c_client *client,
> > +			 const struct i2c_device_id *id)
> > +{
> > +	struct iio_dev *indio_dev;
> > +	struct ltc2309 *ltc2309;
> > +	int ret = 0;
> > +
> > +	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*ltc2309));
> > +	if (!indio_dev)
> > +		return -ENOMEM;
> > +
> > +	i2c_set_clientdata(client, indio_dev);
> > +
> > +	ltc2309 = iio_priv(indio_dev);
> > +	ltc2309->dev = &indio_dev->dev;
> > +	ltc2309->client = client;
> > +	ltc2309->vref_mv = 4096; /* Default to the internal ref */
> > +
> > +	indio_dev->name = DRIVER_NAME;
> > +	indio_dev->dev.parent = &client->dev;
> > +	indio_dev->modes = INDIO_DIRECT_MODE;
> > +	indio_dev->channels = ltc2309_channels;
> > +	indio_dev->num_channels = ARRAY_SIZE(ltc2309_channels);
> > +	indio_dev->info = &ltc2309_info;
> > +
> > +	ltc2309->refcomp = devm_regulator_get_optional(&client->dev, "refcomp");
> > +	if (!IS_ERR_OR_NULL(ltc2309->refcomp)) {
> > +		ret = regulator_enable(ltc2309->refcomp);
> > +		if (ret) {
> > +			dev_err(ltc2309->dev, "failed to enable REFCOMP\n");
> > +			return ret;
> > +		}
> > +
> > +		ret = regulator_get_voltage(ltc2309->refcomp);
> > +		if (ret < 0)
> 
> You have unbalanced regulator. Same in all further error paths.
> 

Right, will fix.

I was going to add an action with devm_add_action_or_reset(), and
noticed a lot of duplicate code adding a custom disable action. Does
adding something like this make sense?

-- >8 --

diff --git a/drivers/regulator/devres.c b/drivers/regulator/devres.c
index 90bb0d178885..ff94f35fad87 100644
--- a/drivers/regulator/devres.c
+++ b/drivers/regulator/devres.c
@@ -70,12 +70,17 @@ struct regulator *devm_regulator_get_exclusive(struct device *dev,
 }
 EXPORT_SYMBOL_GPL(devm_regulator_get_exclusive);

-static void regulator_action_disable(void *d)
+/**
+ * regulator_action_disable - Generic disable action for managed resource
+ * @d: regulator to disable
+ */
+void regulator_action_disable(void *d)
 {
 	struct regulator *r = (struct regulator *)d;

 	regulator_disable(r);
 }
+EXPORT_SYMBOL_GPL(regulator_action_disable);

 static int _devm_regulator_get_enable(struct device *dev, const char *id,
 				      int get_type)
diff --git a/include/linux/regulator/consumer.h b/include/linux/regulator/consumer.h
index 39b666b40ea6..4c018af5d008 100644
--- a/include/linux/regulator/consumer.h
+++ b/include/linux/regulator/consumer.h
@@ -207,6 +207,8 @@ struct regulator *__must_check regulator_get_optional(struct device *dev,
 						      const char *id);
 struct regulator *__must_check devm_regulator_get_optional(struct device *dev,
 							   const char *id);
+
+void regulator_action_disable(void *d);
 int devm_regulator_get_enable(struct device *dev, const char *id);
 int devm_regulator_get_enable_optional(struct device *dev, const char *id);
 void regulator_put(struct regulator *regulator);

-- >8 --

This would let consumers reuse it directly with something like:

	devm_add_action_or_reset(ltc2309->dev,
				 regulator_action_disable,
				 ltc2309->vref);


Maybe it should be a separate series, including the cleanup?

> > +			return ret;
> > +
> > +		ltc2309->vref_mv = ret / 1000;
> > +		if (ret)
> > +			return ret;

I just noticed this extra if. will remove too.

> > +	}
> > +
> > +	mutex_init(&ltc2309->lock);
> > +
> > +	return devm_iio_device_register(&client->dev, indio_dev);
> > +}
> > +
> 
> 
> Best regards,
> Krzysztof
> 

Thanks,
Liam

Patchew 2.1-devel-b67e4c2

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