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Subject[PATCH 1/3] iio: amplifiers: hmc425a: Add support for HMC425A step attenuator with gpio interface
Date
From: Michael Hennerich <michael.hennerich@analog.com>

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 <michael.hennerich@analog.com>
Signed-off-by: Alexandru Ardelean <alexandru.ardelean@analog.com>
Signed-off-by: Beniamin Bia <beniamin.bia@analog.com>
---
drivers/iio/amplifiers/Kconfig | 10 ++
drivers/iio/amplifiers/Makefile | 1 +
drivers/iio/amplifiers/hmc425a.c | 247 +++++++++++++++++++++++++++++++
3 files changed, 258 insertions(+)
create mode 100644 drivers/iio/amplifiers/hmc425a.c

diff --git a/drivers/iio/amplifiers/Kconfig b/drivers/iio/amplifiers/Kconfig
index da7f126d197b..9b02c9a2bc8a 100644
--- a/drivers/iio/amplifiers/Kconfig
+++ b/drivers/iio/amplifiers/Kconfig
@@ -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
diff --git a/drivers/iio/amplifiers/Makefile b/drivers/iio/amplifiers/Makefile
index 9abef2ebe9bc..19a89db1d9b1 100644
--- a/drivers/iio/amplifiers/Makefile
+++ b/drivers/iio/amplifiers/Makefile
@@ -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
diff --git a/drivers/iio/amplifiers/hmc425a.c b/drivers/iio/amplifiers/hmc425a.c
new file mode 100644
index 000000000000..525ebadaf1e8
--- /dev/null
+++ b/drivers/iio/amplifiers/hmc425a.c
@@ -0,0 +1,247 @@
+// 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 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);
+ int i, *values;
+
+ values = kmalloc_array(st->chip_info->num_gpios, sizeof(int),
+ GFP_KERNEL);
+ if (!values)
+ return -ENOMEM;
+
+ for (i = 0; i < st->chip_info->num_gpios; i++)
+ values[i] = (value >> i) & 1;
+
+ gpiod_set_array_value_cansleep(st->gpios->ndescs, st->gpios->desc,
+ values);
+ kfree(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;
+ }
+
+ /* Values in dB */
+ *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;
+
+ /* Values in dB */
+ 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 const struct iio_info hmc425a_info = {
+ .read_raw = &hmc425a_read_raw,
+ .write_raw = &hmc425a_write_raw,
+};
+
+#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_remove(void *data)
+{
+ struct hmc425a_state *st = data;
+
+ regulator_disable(st->reg);
+}
+
+static struct hmc425a_chip_info hmc425a_chip_info_tbl[] = {
+ [ID_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 device_node *np = pdev->dev.of_node;
+ const struct of_device_id *id;
+ 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);
+ id = of_match_device(hmc425a_of_match, &pdev->dev);
+ if (!id)
+ ret = -ENODEV;
+
+ st->type = (enum hmc425a_type)id->data;
+
+ 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;
+ 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");
+ 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(&pdev->dev, "vcc");
+ if (!IS_ERR(st->reg)) {
+ ret = regulator_enable(st->reg);
+ if (ret)
+ return ret;
+ ret = devm_add_action_or_reset(&pdev->dev, hmc425a_remove, st);
+ if (ret)
+ return ret;
+ }
+
+ platform_set_drvdata(pdev, indio_dev);
+ mutex_init(&st->lock);
+
+ indio_dev->dev.parent = &pdev->dev;
+ indio_dev->name = np->name;
+ 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 <michael.hennerich@analog.com>");
+MODULE_DESCRIPTION(
+ "Analog Devices HMC425A and similar GPIO control Gain Amplifiers");
+MODULE_LICENSE("GPL v2");
--
2.17.1
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