iio: core: Handle 'dB' suffix in core

This patch add write_raw_get_fmt function to specify conversion for hardware gain.

Signed-off-by Beniamin Bia <[email protected]>

---
Changes in v5:

(quoted diff) +0 -1

-nothing changed
 
 drivers/iio/amplifiers/ad8366.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

drivers/iio/amplifiers/ad8366.c +13 -0

index 0176d3d8cc9c..95972ab60f42 100644
@@ -180,9 +180,22 @@ static int ad8366_write_raw(struct iio_dev *indio_dev,
 	return ret;
 }
 
+static int ad8366_write_raw_get_fmt(struct iio_dev *indio_dev,
+				    struct iio_chan_spec const *chan,
+				    long mask)
+{
+	switch (mask) {
+	case IIO_CHAN_INFO_HARDWAREGAIN:
+		return IIO_VAL_INT_PLUS_MICRO_DB;
+	default:
+		return -EINVAL;
+	}
+}
+
 static const struct iio_info ad8366_info = {
 	.read_raw = &ad8366_read_raw,
 	.write_raw = &ad8366_write_raw,
+	.write_raw_get_fmt = &ad8366_write_raw_get_fmt,
 };
 
 #define AD8366_CHAN(_channel) {				\

This patch adds support for the HMC425A 0.5 dB LSB GaAs MMIC 6-BIT DIGITAL POSITIVE CONTROL ATTENUATOR, 2.2 - 8.0 GHz.

Datasheet:
https://www.analog.com/media/en/technical-documentation/data-sheets/hmc425A.pdf

Signed-off-by Michael Hennerich <[email protected]>

Signed-off-by Alexandru Ardelean <[email protected]>

Signed-off-by Beniamin Bia <[email protected]>

---
Changes in v5:

(quoted diff) +0 -2

-properties in HMC425A_CHAN on separate lines
-of_device_get_match instead of of_match_device
 
 drivers/iio/amplifiers/Kconfig   |  10 ++
 drivers/iio/amplifiers/Makefile  |   1 +
 drivers/iio/amplifiers/hmc425a.c | 253 +++++++++++++++++++++++++++++++
 3 files changed, 264 insertions(+)
 create mode 100644 drivers/iio/amplifiers/hmc425a.c

drivers/iio/amplifiers/Kconfig +10 -0

index da7f126d197b..9b02c9a2bc8a 100644
@@ -22,4 +22,14 @@ config AD8366
 	  To compile this driver as a module, choose M here: the
 	  module will be called ad8366.
 
+config HMC425
+	tristate "Analog Devices HMC425A and similar GPIO Gain Amplifiers"
+	depends on GPIOLIB
+	help
+	  Say yes here to build support for Analog Devices HMC425A and similar
+	  gain amplifiers or step attenuators.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called hmc425a.
+
 endmenu

drivers/iio/amplifiers/Makefile +0 -0

index 9abef2ebe9bc..19a89db1d9b1 100644

drivers/iio/amplifiers/hmc425a.c new file +207 -0

new file mode 100644
index 000000000000..b0d624a7ad05
@@ -0,0 +1,253 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * HMC425A and similar Gain Amplifiers
+ *
+ * Copyright 2020 Analog Devices Inc.
+ */
+
+#include <linux/device.h>
+#include <linux/err.h>
+#include <linux/gpio/consumer.h>
+#include <linux/iio/iio.h>
+#include <linux/iio/sysfs.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of_device.h>
+#include <linux/of_platform.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+#include <linux/regulator/consumer.h>
+#include <linux/sysfs.h>
+
+enum hmc425a_type {
+	ID_HMC425A,
+};
+
+struct hmc425a_chip_info {
+	const char			*name;
+	const struct iio_chan_spec	*channels;
+	unsigned int			num_channels;
+	unsigned int			num_gpios;
+	int				gain_min;
+	int				gain_max;
+	int				default_gain;
+};
+
+struct hmc425a_state {
+	struct	regulator *reg;
+	struct	mutex lock; /* protect sensor state */
+	struct	hmc425a_chip_info *chip_info;
+	struct	gpio_descs *gpios;
+	enum	hmc425a_type type;
+	u32	gain;
+};
+
+static int hmc425a_write(struct iio_dev *indio_dev, u32 value)
+{
+	struct hmc425a_state *st = iio_priv(indio_dev);
+	DECLARE_BITMAP(values, BITS_PER_TYPE(value));
+
+	values[0] = value;
+
+	gpiod_set_array_value_cansleep(st->gpios->ndescs, st->gpios->desc,
+				       NULL, values);
+	return 0;
+}
+
+static int hmc425a_read_raw(struct iio_dev *indio_dev,
+			    struct iio_chan_spec const *chan, int *val,
+			    int *val2, long m)
+{
+	struct hmc425a_state *st = iio_priv(indio_dev);
+	int code, gain = 0;
+	int ret;
+
+	mutex_lock(&st->lock);
+	switch (m) {
+	case IIO_CHAN_INFO_HARDWAREGAIN:
+		code = st->gain;
+
+		switch (st->type) {
+		case ID_HMC425A:
+			gain = ~code * -500;
+			break;
+		}
+
+		*val = gain / 1000;
+		*val2 = (gain % 1000) * 1000;
+
+		ret = IIO_VAL_INT_PLUS_MICRO_DB;
+		break;
+	default:
+		ret = -EINVAL;
+	}
+	mutex_unlock(&st->lock);
+
+	return ret;
+};
+
+static int hmc425a_write_raw(struct iio_dev *indio_dev,
+			     struct iio_chan_spec const *chan, int val,
+			     int val2, long mask)
+{
+	struct hmc425a_state *st = iio_priv(indio_dev);
+	struct hmc425a_chip_info *inf = st->chip_info;
+	int code = 0, gain;
+	int ret;
+
+	if (val < 0)
+		gain = (val * 1000) - (val2 / 1000);
+	else
+		gain = (val * 1000) + (val2 / 1000);
+
+	if (gain > inf->gain_max || gain < inf->gain_min)
+		return -EINVAL;
+
+	switch (st->type) {
+	case ID_HMC425A:
+		code = ~((abs(gain) / 500) & 0x3F);
+		break;
+	}
+
+	mutex_lock(&st->lock);
+	switch (mask) {
+	case IIO_CHAN_INFO_HARDWAREGAIN:
+		st->gain = code;
+
+		ret = hmc425a_write(indio_dev, st->gain);
+		break;
+	default:
+		ret = -EINVAL;
+	}
+	mutex_unlock(&st->lock);
+
+	return ret;
+}
+
+static int hmc425a_write_raw_get_fmt(struct iio_dev *indio_dev,
+				     struct iio_chan_spec const *chan,
+				     long mask)
+{
+	switch (mask) {
+	case IIO_CHAN_INFO_HARDWAREGAIN:
+		return IIO_VAL_INT_PLUS_MICRO_DB;
+	default:
+		return -EINVAL;
+	}
+}
+
+static const struct iio_info hmc425a_info = {
+	.read_raw = &hmc425a_read_raw,
+	.write_raw = &hmc425a_write_raw,
+	.write_raw_get_fmt = &hmc425a_write_raw_get_fmt,
+};
+
+#define HMC425A_CHAN(_channel)						\
+{									\
+	.type = IIO_VOLTAGE,						\
+	.output = 1,							\
+	.indexed = 1,							\
+	.channel = _channel,						\
+	.info_mask_separate = BIT(IIO_CHAN_INFO_HARDWAREGAIN),		\
+}
+
+static const struct iio_chan_spec hmc425a_channels[] = {
+	HMC425A_CHAN(0),
+};
+
+/* Match table for of_platform binding */
+static const struct of_device_id hmc425a_of_match[] = {
+	{ .compatible = "adi,hmc425a", .data = (void *)ID_HMC425A },
+	{},
+};
+MODULE_DEVICE_TABLE(of, hmc425a_of_match);
+
+static void hmc425a_reg_disable(void *data)
+{
+	struct hmc425a_state *st = data;
+
+	regulator_disable(st->reg);
+}
+
+static struct hmc425a_chip_info hmc425a_chip_info_tbl[] = {
+	[ID_HMC425A] = {
+		.name = "hmc425a",
+		.channels = hmc425a_channels,
+		.num_channels = ARRAY_SIZE(hmc425a_channels),
+		.num_gpios = 6,
+		.gain_min = -31500,
+		.gain_max = 0,
+		.default_gain = -0x40, /* set default gain -31.5db*/
+	},
+};
+
+static int hmc425a_probe(struct platform_device *pdev)
+{
+	struct iio_dev *indio_dev;
+	struct hmc425a_state *st;
+	int ret;
+
+	indio_dev = devm_iio_device_alloc(&pdev->dev, sizeof(*st));
+	if (!indio_dev)
+		return -ENOMEM;
+
+	st = iio_priv(indio_dev);
+	st->type = (enum hmc425a_type)of_device_get_match_data(&pdev->dev);
+
+	st->chip_info = &hmc425a_chip_info_tbl[st->type];
+	indio_dev->num_channels = st->chip_info->num_channels;
+	indio_dev->channels = st->chip_info->channels;
+	indio_dev->name = st->chip_info->name;
+	st->gain = st->chip_info->default_gain;
+
+	st->gpios = devm_gpiod_get_array(&pdev->dev, "ctrl", GPIOD_OUT_LOW);
+	if (IS_ERR(st->gpios)) {
+		ret = PTR_ERR(st->gpios);
+		if (ret != -EPROBE_DEFER)
+			dev_err(&pdev->dev, "failed to get gpios\n");

drivers/iio/amplifiers/hmc425a.c new file +36 -0

+	if (IS_ERR(st->reg)) {
+		if (PTR_ERR(st->reg) == -EPROBE_DEFER)
+			return -EPROBE_DEFER;
+
+		st->reg = NULL;
+	} else {
+		ret = regulator_enable(st->reg);
+		if (ret)
+			return ret;
+		ret = devm_add_action_or_reset(&pdev->dev, hmc425a_reg_disable,
+					       st);
+		if (ret)
+			return ret;
+	}
+
+	mutex_init(&st->lock);
+
+	indio_dev->dev.parent = &pdev->dev;
+	indio_dev->info = &hmc425a_info;
+	indio_dev->modes = INDIO_DIRECT_MODE;
+
+	return devm_iio_device_register(&pdev->dev, indio_dev);
+}
+
+static struct platform_driver hmc425a_driver = {
+	.driver = {
+		.name = KBUILD_MODNAME,
+		.of_match_table = hmc425a_of_match,
+	},
+	.probe = hmc425a_probe,
+};
+module_platform_driver(hmc425a_driver);
+
+MODULE_AUTHOR("Michael Hennerich <[email protected]>");
+MODULE_DESCRIPTION("Analog Devices HMC425A and similar GPIO control Gain Amplifiers");
+MODULE_LICENSE("GPL v2");

[External]

Quoted 5 lines · On Thu, 6 Feb 2020 17:11:47 +0200 Beniamin Bia <[email protected]> wrote:

This patch adds support for the HMC425A 0.5 dB LSB GaAs MMIC 6-BIT DIGITAL POSITIVE CONTROL ATTENUATOR, 2.2 - 8.0 GHz.

Datasheet:

Quoted 4 lines

Signed-off-by Michael Hennerich <[email protected]>

Signed-off-by Alexandru Ardelean <[email protected]>

Signed-off-by Beniamin Bia <[email protected]>

2 things left in here. I'll have a go at fixing them up to save us going
to v6 but please take a look at the result and check I haven't broken anything!

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

Thanks,

Jonathan

Quoted 40 lines

---
Changes in v5:

(quoted diff) +1 -2

-properties in HMC425A_CHAN on separate lines
-of_device_get_match instead of of_match_device
 
 drivers/iio/amplifiers/Kconfig   |  10 ++
 drivers/iio/amplifiers/Makefile  |   1 +
 drivers/iio/amplifiers/hmc425a.c | 253
+++++++++++++++++++++++++++++++
 3 files changed, 264 insertions(+)
 create mode 100644 drivers/iio/amplifiers/hmc425a.c

drivers/iio/amplifiers/Kconfig +2 -0

index da7f126d197b..9b02c9a2bc8a 100644
@@ -22,4 +22,14 @@ config AD8366
 	  To compile this driver as a module, choose M here: the
 	  module will be called ad8366.
 
+config HMC425
+	tristate "Analog Devices HMC425A and similar GPIO Gain

Amplifiers"

drivers/iio/amplifiers/Kconfig +3 -0

+	depends on GPIOLIB
+	help
+	  Say yes here to build support for Analog Devices HMC425A and

similar

drivers/iio/amplifiers/Kconfig +5 -0

+	  gain amplifiers or step attenuators.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called hmc425a.
+
 endmenu

drivers/iio/amplifiers/Makefile +0 -0

index 9abef2ebe9bc..19a89db1d9b1 100644

drivers/iio/amplifiers/Makefile line 8

Quoted 5 lines

drivers/iio/amplifiers/Makefile +1 -0

@@ -5,3 +5,4 @@
 
 # When adding new entries keep the list in alphabetical order
 obj-$(CONFIG_AD8366) += ad8366.o
+obj-$(CONFIG_HMC425) += hmc425a.o
\ No newline at end of file

I'll fix the no newline..

Quoted 234 lines

drivers/iio/amplifiers/hmc425a.c new file +52 -0

new file mode 100644
index 000000000000..b0d624a7ad05
@@ -0,0 +1,253 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * HMC425A and similar Gain Amplifiers
+ *
+ * Copyright 2020 Analog Devices Inc.
+ */
+
+#include <linux/device.h>
+#include <linux/err.h>
+#include <linux/gpio/consumer.h>
+#include <linux/iio/iio.h>
+#include <linux/iio/sysfs.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of_device.h>
+#include <linux/of_platform.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+#include <linux/regulator/consumer.h>
+#include <linux/sysfs.h>
+
+enum hmc425a_type {
+	ID_HMC425A,
+};
+
+struct hmc425a_chip_info {
+	const char			*name;
+	const struct iio_chan_spec	*channels;
+	unsigned int			num_channels;
+	unsigned int			num_gpios;
+	int				gain_min;
+	int				gain_max;
+	int				default_gain;
+};
+
+struct hmc425a_state {
+	struct	regulator *reg;
+	struct	mutex lock; /* protect sensor state */
+	struct	hmc425a_chip_info *chip_info;
+	struct	gpio_descs *gpios;
+	enum	hmc425a_type type;
+	u32	gain;
+};
+
+static int hmc425a_write(struct iio_dev *indio_dev, u32 value)
+{
+	struct hmc425a_state *st = iio_priv(indio_dev);
+	DECLARE_BITMAP(values, BITS_PER_TYPE(value));
+
+	values[0] = value;
+
+	gpiod_set_array_value_cansleep(st->gpios->ndescs, st->gpios-

Quoted 1 line

desc,

drivers/iio/amplifiers/hmc425a.c new file +93 -0

+				       NULL, values);
+	return 0;
+}
+
+static int hmc425a_read_raw(struct iio_dev *indio_dev,
+			    struct iio_chan_spec const *chan, int *val,
+			    int *val2, long m)
+{
+	struct hmc425a_state *st = iio_priv(indio_dev);
+	int code, gain = 0;
+	int ret;
+
+	mutex_lock(&st->lock);
+	switch (m) {
+	case IIO_CHAN_INFO_HARDWAREGAIN:
+		code = st->gain;
+
+		switch (st->type) {
+		case ID_HMC425A:
+			gain = ~code * -500;
+			break;
+		}
+
+		*val = gain / 1000;
+		*val2 = (gain % 1000) * 1000;
+
+		ret = IIO_VAL_INT_PLUS_MICRO_DB;
+		break;
+	default:
+		ret = -EINVAL;
+	}
+	mutex_unlock(&st->lock);
+
+	return ret;
+};
+
+static int hmc425a_write_raw(struct iio_dev *indio_dev,
+			     struct iio_chan_spec const *chan, int val,
+			     int val2, long mask)
+{
+	struct hmc425a_state *st = iio_priv(indio_dev);
+	struct hmc425a_chip_info *inf = st->chip_info;
+	int code = 0, gain;
+	int ret;
+
+	if (val < 0)
+		gain = (val * 1000) - (val2 / 1000);
+	else
+		gain = (val * 1000) + (val2 / 1000);
+
+	if (gain > inf->gain_max || gain < inf->gain_min)
+		return -EINVAL;
+
+	switch (st->type) {
+	case ID_HMC425A:
+		code = ~((abs(gain) / 500) & 0x3F);
+		break;
+	}
+
+	mutex_lock(&st->lock);
+	switch (mask) {
+	case IIO_CHAN_INFO_HARDWAREGAIN:
+		st->gain = code;
+
+		ret = hmc425a_write(indio_dev, st->gain);
+		break;
+	default:
+		ret = -EINVAL;
+	}
+	mutex_unlock(&st->lock);
+
+	return ret;
+}
+
+static int hmc425a_write_raw_get_fmt(struct iio_dev *indio_dev,
+				     struct iio_chan_spec const *chan,
+				     long mask)
+{
+	switch (mask) {
+	case IIO_CHAN_INFO_HARDWAREGAIN:
+		return IIO_VAL_INT_PLUS_MICRO_DB;
+	default:
+		return -EINVAL;
+	}
+}
+
+static const struct iio_info hmc425a_info = {
+	.read_raw = &hmc425a_read_raw,
+	.write_raw = &hmc425a_write_raw,
+	.write_raw_get_fmt = &hmc425a_write_raw_get_fmt,
+};
+
+#define HMC425A_CHAN(_channel)					

	\

+{
\

drivers/iio/amplifiers/hmc425a.c new file +1 -0

+	.type = IIO_VOLTAGE,						

\

drivers/iio/amplifiers/hmc425a.c new file +1 -0

+	.output = 1,							

\

drivers/iio/amplifiers/hmc425a.c new file +1 -0

+	.indexed = 1,							

\

drivers/iio/amplifiers/hmc425a.c new file +1 -0

+	.channel = _channel,						

\

drivers/iio/amplifiers/hmc425a.c new file +1 -0

+	.info_mask_separate = BIT(IIO_CHAN_INFO_HARDWAREGAIN),		

\

drivers/iio/amplifiers/hmc425a.c new file +44 -0

+}
+
+static const struct iio_chan_spec hmc425a_channels[] = {
+	HMC425A_CHAN(0),
+};
+
+/* Match table for of_platform binding */
+static const struct of_device_id hmc425a_of_match[] = {
+	{ .compatible = "adi,hmc425a", .data = (void *)ID_HMC425A },
+	{},
+};
+MODULE_DEVICE_TABLE(of, hmc425a_of_match);
+
+static void hmc425a_reg_disable(void *data)
+{
+	struct hmc425a_state *st = data;
+
+	regulator_disable(st->reg);
+}
+
+static struct hmc425a_chip_info hmc425a_chip_info_tbl[] = {
+	[ID_HMC425A] = {
+		.name = "hmc425a",
+		.channels = hmc425a_channels,
+		.num_channels = ARRAY_SIZE(hmc425a_channels),
+		.num_gpios = 6,
+		.gain_min = -31500,
+		.gain_max = 0,
+		.default_gain = -0x40, /* set default gain -31.5db*/
+	},
+};
+
+static int hmc425a_probe(struct platform_device *pdev)
+{
+	struct iio_dev *indio_dev;
+	struct hmc425a_state *st;
+	int ret;
+
+	indio_dev = devm_iio_device_alloc(&pdev->dev, sizeof(*st));
+	if (!indio_dev)
+		return -ENOMEM;
+
+	st = iio_priv(indio_dev);
+	st->type = (enum hmc425a_type)of_device_get_match_data(&pdev-

Quoted 1 line

dev);

drivers/iio/amplifiers/hmc425a.c new file +8 -0

+
+	st->chip_info = &hmc425a_chip_info_tbl[st->type];
+	indio_dev->num_channels = st->chip_info->num_channels;
+	indio_dev->channels = st->chip_info->channels;
+	indio_dev->name = st->chip_info->name;
+	st->gain = st->chip_info->default_gain;
+
+	st->gpios = devm_gpiod_get_array(&pdev->dev, "ctrl",

GPIOD_OUT_LOW);

drivers/iio/amplifiers/hmc425a.c new file +14 -0

+	if (IS_ERR(st->gpios)) {
+		ret = PTR_ERR(st->gpios);
+		if (ret != -EPROBE_DEFER)
+			dev_err(&pdev->dev, "failed to get gpios\n");
+		return ret;
+	}
+
+	if (st->gpios->ndescs != st->chip_info->num_gpios) {
+		dev_err(&pdev->dev, "%d GPIOs needed to operate\n",
+			st->chip_info->num_gpios);
+		return -ENODEV;
+	}
+
+	st->reg = devm_regulator_get_optional(&pdev->dev, "vcc-

Quoted 1 line

supply");

Sorry I'd missed this before. Why is this optional? I think what is needed here is to just let the regulator framework provide a stub if no regulator is supplied in DT.

We only play this optional game if we have regulators that are really optional such as reference voltages on parts that also have internal references that can be used.

Quoted 38 lines

drivers/iio/amplifiers/hmc425a.c new file +10 -0

+	if (IS_ERR(st->reg)) {
+		if (PTR_ERR(st->reg) == -EPROBE_DEFER)
+			return -EPROBE_DEFER;
+
+		st->reg = NULL;
+	} else {
+		ret = regulator_enable(st->reg);
+		if (ret)
+			return ret;
+		ret = devm_add_action_or_reset(&pdev->dev,

hmc425a_reg_disable,

drivers/iio/amplifiers/hmc425a.c new file +25 -0

+					       st);
+		if (ret)
+			return ret;
+	}
+
+	mutex_init(&st->lock);
+
+	indio_dev->dev.parent = &pdev->dev;
+	indio_dev->info = &hmc425a_info;
+	indio_dev->modes = INDIO_DIRECT_MODE;
+
+	return devm_iio_device_register(&pdev->dev, indio_dev);
+}
+
+static struct platform_driver hmc425a_driver = {
+	.driver = {
+		.name = KBUILD_MODNAME,
+		.of_match_table = hmc425a_of_match,
+	},
+	.probe = hmc425a_probe,
+};
+module_platform_driver(hmc425a_driver);
+
+MODULE_AUTHOR("Michael Hennerich <[email protected]>");
+MODULE_DESCRIPTION("Analog Devices HMC425A and similar GPIO

control Gain Amplifiers");
+MODULE_LICENSE("GPL v2");

Hi,

I checked the modifications and everything works as expected.

Thanks,
Ben

Quoted 10 lines · Jonathan Cameron

[External]

Quoted 5 lines · On Thu, 6 Feb 2020 17:11:47 +0200 Beniamin Bia <[email protected]> wrote:

This patch adds support for the HMC425A 0.5 dB LSB GaAs MMIC 6-BIT DIGITAL POSITIVE CONTROL ATTENUATOR, 2.2 - 8.0 GHz.

Datasheet:

https://www.analog.com/media/en/technical-documentation/data-sheets/hmc425A.pdf

Quoted 349 lines

Quoted 4 lines

Signed-off-by Michael Hennerich <[email protected]>

Signed-off-by Alexandru Ardelean <[email protected]>

Signed-off-by Beniamin Bia <[email protected]>

2 things left in here. I'll have a go at fixing them up to save us going
to v6 but please take a look at the result and check I haven't broken anything!

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

Thanks,

Jonathan

Quoted 40 lines

---
Changes in v5:

(quoted diff) +1 -2

-properties in HMC425A_CHAN on separate lines
-of_device_get_match instead of of_match_device
 
 drivers/iio/amplifiers/Kconfig   |  10 ++
 drivers/iio/amplifiers/Makefile  |   1 +
 drivers/iio/amplifiers/hmc425a.c | 253
+++++++++++++++++++++++++++++++
 3 files changed, 264 insertions(+)
 create mode 100644 drivers/iio/amplifiers/hmc425a.c

drivers/iio/amplifiers/Kconfig +2 -0

index da7f126d197b..9b02c9a2bc8a 100644
@@ -22,4 +22,14 @@ config AD8366
 	  To compile this driver as a module, choose M here: the
 	  module will be called ad8366.
 
+config HMC425
+	tristate "Analog Devices HMC425A and similar GPIO Gain

Amplifiers"

drivers/iio/amplifiers/Kconfig +3 -0

+	depends on GPIOLIB
+	help
+	  Say yes here to build support for Analog Devices HMC425A and

similar

drivers/iio/amplifiers/Kconfig +5 -0

+	  gain amplifiers or step attenuators.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called hmc425a.
+
 endmenu

drivers/iio/amplifiers/Makefile +0 -0

index 9abef2ebe9bc..19a89db1d9b1 100644

drivers/iio/amplifiers/Makefile line 8

Quoted 5 lines

drivers/iio/amplifiers/Makefile +1 -0

@@ -5,3 +5,4 @@
 
 # When adding new entries keep the list in alphabetical order
 obj-$(CONFIG_AD8366) += ad8366.o
+obj-$(CONFIG_HMC425) += hmc425a.o
\ No newline at end of file  

I'll fix the no newline..

Quoted 234 lines

drivers/iio/amplifiers/hmc425a.c new file +52 -0

new file mode 100644
index 000000000000..b0d624a7ad05
@@ -0,0 +1,253 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * HMC425A and similar Gain Amplifiers
+ *
+ * Copyright 2020 Analog Devices Inc.
+ */
+
+#include <linux/device.h>
+#include <linux/err.h>
+#include <linux/gpio/consumer.h>
+#include <linux/iio/iio.h>
+#include <linux/iio/sysfs.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of_device.h>
+#include <linux/of_platform.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+#include <linux/regulator/consumer.h>
+#include <linux/sysfs.h>
+
+enum hmc425a_type {
+	ID_HMC425A,
+};
+
+struct hmc425a_chip_info {
+	const char			*name;
+	const struct iio_chan_spec	*channels;
+	unsigned int			num_channels;
+	unsigned int			num_gpios;
+	int				gain_min;
+	int				gain_max;
+	int				default_gain;
+};
+
+struct hmc425a_state {
+	struct	regulator *reg;
+	struct	mutex lock; /* protect sensor state */
+	struct	hmc425a_chip_info *chip_info;
+	struct	gpio_descs *gpios;
+	enum	hmc425a_type type;
+	u32	gain;
+};
+
+static int hmc425a_write(struct iio_dev *indio_dev, u32 value)
+{
+	struct hmc425a_state *st = iio_priv(indio_dev);
+	DECLARE_BITMAP(values, BITS_PER_TYPE(value));
+
+	values[0] = value;
+
+	gpiod_set_array_value_cansleep(st->gpios->ndescs, st->gpios-  

Quoted 1 line

desc,

drivers/iio/amplifiers/hmc425a.c new file +93 -0

+				       NULL, values);
+	return 0;
+}
+
+static int hmc425a_read_raw(struct iio_dev *indio_dev,
+			    struct iio_chan_spec const *chan, int *val,
+			    int *val2, long m)
+{
+	struct hmc425a_state *st = iio_priv(indio_dev);
+	int code, gain = 0;
+	int ret;
+
+	mutex_lock(&st->lock);
+	switch (m) {
+	case IIO_CHAN_INFO_HARDWAREGAIN:
+		code = st->gain;
+
+		switch (st->type) {
+		case ID_HMC425A:
+			gain = ~code * -500;
+			break;
+		}
+
+		*val = gain / 1000;
+		*val2 = (gain % 1000) * 1000;
+
+		ret = IIO_VAL_INT_PLUS_MICRO_DB;
+		break;
+	default:
+		ret = -EINVAL;
+	}
+	mutex_unlock(&st->lock);
+
+	return ret;
+};
+
+static int hmc425a_write_raw(struct iio_dev *indio_dev,
+			     struct iio_chan_spec const *chan, int val,
+			     int val2, long mask)
+{
+	struct hmc425a_state *st = iio_priv(indio_dev);
+	struct hmc425a_chip_info *inf = st->chip_info;
+	int code = 0, gain;
+	int ret;
+
+	if (val < 0)
+		gain = (val * 1000) - (val2 / 1000);
+	else
+		gain = (val * 1000) + (val2 / 1000);
+
+	if (gain > inf->gain_max || gain < inf->gain_min)
+		return -EINVAL;
+
+	switch (st->type) {
+	case ID_HMC425A:
+		code = ~((abs(gain) / 500) & 0x3F);
+		break;
+	}
+
+	mutex_lock(&st->lock);
+	switch (mask) {
+	case IIO_CHAN_INFO_HARDWAREGAIN:
+		st->gain = code;
+
+		ret = hmc425a_write(indio_dev, st->gain);
+		break;
+	default:
+		ret = -EINVAL;
+	}
+	mutex_unlock(&st->lock);
+
+	return ret;
+}
+
+static int hmc425a_write_raw_get_fmt(struct iio_dev *indio_dev,
+				     struct iio_chan_spec const *chan,
+				     long mask)
+{
+	switch (mask) {
+	case IIO_CHAN_INFO_HARDWAREGAIN:
+		return IIO_VAL_INT_PLUS_MICRO_DB;
+	default:
+		return -EINVAL;
+	}
+}
+
+static const struct iio_info hmc425a_info = {
+	.read_raw = &hmc425a_read_raw,
+	.write_raw = &hmc425a_write_raw,
+	.write_raw_get_fmt = &hmc425a_write_raw_get_fmt,
+};
+
+#define HMC425A_CHAN(_channel)					

	\

+{
\

drivers/iio/amplifiers/hmc425a.c new file +1 -0

+	.type = IIO_VOLTAGE,						

\

drivers/iio/amplifiers/hmc425a.c new file +1 -0

+	.output = 1,							

\

drivers/iio/amplifiers/hmc425a.c new file +1 -0

+	.indexed = 1,							

\

drivers/iio/amplifiers/hmc425a.c new file +1 -0

+	.channel = _channel,						

\

drivers/iio/amplifiers/hmc425a.c new file +1 -0

+	.info_mask_separate = BIT(IIO_CHAN_INFO_HARDWAREGAIN),		

\

drivers/iio/amplifiers/hmc425a.c new file +44 -0

+}
+
+static const struct iio_chan_spec hmc425a_channels[] = {
+	HMC425A_CHAN(0),
+};
+
+/* Match table for of_platform binding */
+static const struct of_device_id hmc425a_of_match[] = {
+	{ .compatible = "adi,hmc425a", .data = (void *)ID_HMC425A },
+	{},
+};
+MODULE_DEVICE_TABLE(of, hmc425a_of_match);
+
+static void hmc425a_reg_disable(void *data)
+{
+	struct hmc425a_state *st = data;
+
+	regulator_disable(st->reg);
+}
+
+static struct hmc425a_chip_info hmc425a_chip_info_tbl[] = {
+	[ID_HMC425A] = {
+		.name = "hmc425a",
+		.channels = hmc425a_channels,
+		.num_channels = ARRAY_SIZE(hmc425a_channels),
+		.num_gpios = 6,
+		.gain_min = -31500,
+		.gain_max = 0,
+		.default_gain = -0x40, /* set default gain -31.5db*/
+	},
+};
+
+static int hmc425a_probe(struct platform_device *pdev)
+{
+	struct iio_dev *indio_dev;
+	struct hmc425a_state *st;
+	int ret;
+
+	indio_dev = devm_iio_device_alloc(&pdev->dev, sizeof(*st));
+	if (!indio_dev)
+		return -ENOMEM;
+
+	st = iio_priv(indio_dev);
+	st->type = (enum hmc425a_type)of_device_get_match_data(&pdev-  

Quoted 1 line

dev);

drivers/iio/amplifiers/hmc425a.c new file +8 -0

+
+	st->chip_info = &hmc425a_chip_info_tbl[st->type];
+	indio_dev->num_channels = st->chip_info->num_channels;
+	indio_dev->channels = st->chip_info->channels;
+	indio_dev->name = st->chip_info->name;
+	st->gain = st->chip_info->default_gain;
+
+	st->gpios = devm_gpiod_get_array(&pdev->dev, "ctrl",

GPIOD_OUT_LOW);

drivers/iio/amplifiers/hmc425a.c new file +14 -0

+	if (IS_ERR(st->gpios)) {
+		ret = PTR_ERR(st->gpios);
+		if (ret != -EPROBE_DEFER)
+			dev_err(&pdev->dev, "failed to get gpios\n");
+		return ret;
+	}
+
+	if (st->gpios->ndescs != st->chip_info->num_gpios) {
+		dev_err(&pdev->dev, "%d GPIOs needed to operate\n",
+			st->chip_info->num_gpios);
+		return -ENODEV;
+	}
+
+	st->reg = devm_regulator_get_optional(&pdev->dev, "vcc-

Quoted 1 line

supply");

Sorry I'd missed this before. Why is this optional? I think what is needed here is to just let the regulator framework provide a stub if no regulator is supplied in DT.

We only play this optional game if we have regulators that are really optional such as reference voltages on parts that also have internal references that can be used.

Quoted 38 lines

drivers/iio/amplifiers/hmc425a.c new file +10 -0

+	if (IS_ERR(st->reg)) {
+		if (PTR_ERR(st->reg) == -EPROBE_DEFER)
+			return -EPROBE_DEFER;
+
+		st->reg = NULL;
+	} else {
+		ret = regulator_enable(st->reg);
+		if (ret)
+			return ret;
+		ret = devm_add_action_or_reset(&pdev->dev,

hmc425a_reg_disable,

drivers/iio/amplifiers/hmc425a.c new file +25 -0

+					       st);
+		if (ret)
+			return ret;
+	}
+
+	mutex_init(&st->lock);
+
+	indio_dev->dev.parent = &pdev->dev;
+	indio_dev->info = &hmc425a_info;
+	indio_dev->modes = INDIO_DIRECT_MODE;
+
+	return devm_iio_device_register(&pdev->dev, indio_dev);
+}
+
+static struct platform_driver hmc425a_driver = {
+	.driver = {
+		.name = KBUILD_MODNAME,
+		.of_match_table = hmc425a_of_match,
+	},
+	.probe = hmc425a_probe,
+};
+module_platform_driver(hmc425a_driver);
+
+MODULE_AUTHOR("Michael Hennerich <[email protected]>");
+MODULE_DESCRIPTION("Analog Devices HMC425A and similar GPIO

control Gain Amplifiers");
+MODULE_LICENSE("GPL v2");

From: Michael Hennerich <[email protected]>

Document support for Analog Devices MC425A Step Attenuator.

Signed-off-by Michael Hennerich <[email protected]>

Signed-off-by Beniamin Bia <[email protected]>

---
Changes in v5:
-minItems added for ctrl_gpios

 .../bindings/iio/amplifiers/adi,hmc425a.yaml  | 49 +++++++++++++++++++
 1 file changed, 49 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/iio/amplifiers/adi,hmc425a.yaml

Quoted 10 lines · Beniamin Bia

From: Michael Hennerich <[email protected]>

Document support for Analog Devices MC425A Step Attenuator.

Signed-off-by Michael Hennerich <[email protected]>

Signed-off-by Beniamin Bia <[email protected]>

---
Changes in v5:
-minItems added for ctrl_gpios

Quoted 3 lines

 .../bindings/iio/amplifiers/adi,hmc425a.yaml  | 49 +++++++++++++++++++
 1 file changed, 49 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/iio/amplifiers/adi,hmc425a.yaml  

Reviewed-by Rob Herring <[email protected]>

Add Beniamin Bia and Michael Hennerich as maintainers for HMC425A attenuator.

Signed-off-by Beniamin Bia <[email protected]>

---
Changes in v5:

(quoted diff) +0 -1

-parse_maintainers runned
 
 MAINTAINERS | 9 +++++++++
 1 file changed, 9 insertions(+)

MAINTAINERS +9 -0

index e699fe378e71..12e39dc0dc93 100644
@@ -1063,6 +1063,15 @@ F:	drivers/iio/adc/ltc249*
 X:	drivers/iio/*/adjd*
 F:	drivers/staging/iio/*/ad*
 
+ANALOG DEVICES INC HMC425A DRIVER
+M:	Beniamin Bia <[email protected]>
+M:	Michael Hennerich <[email protected]>
+L:	[email protected]
+S:	Supported
+W:	http://ez.analog.com/community/linux-device-drivers
+F:	Documentation/devicetree/bindings/iio/amplifiers/adi,hmc425a.yaml
+F:	drivers/iio/amplifiers/hmc425a.c
+
 ANALOGBITS PLL LIBRARIES
 M:	Paul Walmsley <[email protected]>
 S:	Supported

This patch handles the db suffix used for writing micro db values.

Signed-off-by Beniamin Bia <[email protected]>

---
Changes in v5:

(quoted diff) +0 -1

-handle both 'db' and ' db' cases
 
 drivers/iio/industrialio-core.c | 39 ++++++++++++++++++++++++++++++---
 1 file changed, 36 insertions(+), 3 deletions(-)

drivers/iio/industrialio-core.c +1 -1

index 65ff0d067018..684c3b151b29 100644
@@ -769,17 +769,18 @@ static ssize_t iio_read_channel_info_avail(struct device *dev,
 }
 
 /**
- * iio_str_to_fixpoint() - Parse a fixed-point number from a string
+ * __iio_str_to_fixpoint() - Parse a fixed-point number from a string
  * @str: The string to parse
  * @fract_mult: Multiplier for the first decimal place, should be a power of 10
  * @integer: The integer part of the number

drivers/iio/industrialio-core.c +13 -0

 {
 	int i = 0, f = 0;
 	bool integer_part = true, negative = false;

@@ -810,6 +811,14 @@ int iio_str_to_fixpoint(const char *str, int fract_mult,
 				break;
 			else
 				return -EINVAL;
+		} else if (!strncmp(str, " dB", sizeof(" dB") - 1) && scale_db) {
+			/* Ignore the dB suffix */
+			str += sizeof(" dB") - 1;
+			continue;
+		} else if (!strncmp(str, "dB", sizeof("dB") - 1) && scale_db) {
+			/* Ignore the dB suffix */
+			str += sizeof("dB") - 1;
+			continue;
 		} else if (*str == '.' && integer_part) {
 			integer_part = false;
 		} else {

@@ -832,6 +841,22 @@ int iio_str_to_fixpoint(const char *str, int fract_mult,
 }
 EXPORT_SYMBOL_GPL(iio_str_to_fixpoint);
 
+/**
+ * iio_str_to_fixpoint() - Parse a fixed-point number from a string
+ * @str: The string to parse
+ * @fract_mult: Multiplier for the first decimal place, should be a power of 10
+ * @integer: The integer part of the number

drivers/iio/industrialio-core.c +9 -0

+
 static ssize_t iio_write_channel_info(struct device *dev,
 				      struct device_attribute *attr,
 				      const char *buf,

@@ -842,6 +867,7 @@ static ssize_t iio_write_channel_info(struct device *dev,
 	int ret, fract_mult = 100000;
 	int integer, fract = 0;
 	bool is_char = false;
+	bool scale_db = false;
 
 	/* Assumes decimal - precision based on number of digits */
 	if (!indio_dev->info->write_raw)

@@ -853,6 +879,9 @@ static ssize_t iio_write_channel_info(struct device *dev,
 		case IIO_VAL_INT:
 			fract_mult = 0;
 			break;
+		case IIO_VAL_INT_PLUS_MICRO_DB:
+			scale_db = true;
+			/* fall through */
 		case IIO_VAL_INT_PLUS_MICRO:
 			fract_mult = 100000;
 			break;

@@ -877,6 +906,10 @@ static ssize_t iio_write_channel_info(struct device *dev,
 		if (ret)
 			return ret;
 	}
+	ret = __iio_str_to_fixpoint(buf, fract_mult, &integer, &fract,
+				    scale_db);
+	if (ret)
+		return ret;
 
 	ret = indio_dev->info->write_raw(indio_dev, this_attr->c,
 					 integer, fract, this_attr->address);