Re: [PATCH 1/3] iio: amplifiers: hmc425a: Add support for HMC425A step attenuator with gpio interface

Ardelean, Alexandru
2020-01-14T07:17:20Z

On Mon, 2020-01-13 at 16:15 +0200, Beniamin Bia wrote:
> 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);

I think this may be an older variant of the driver.
The 'values' array could be static with a max value.

And the return value of gpiod_set_array_value_cansleep() could be returned
from this function.

> + 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");