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Date:   Thu, 20 Feb 2020 12:32:35 +0000
From:   "Bia, Beniamin" <Beniamin.Bia@...log.com>
To:     "jic23@...nel.org" <jic23@...nel.org>
CC:     "biabeniamin@...look.com" <biabeniamin@...look.com>,
        "lars@...afoo.de" <lars@...afoo.de>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "knaack.h@....de" <knaack.h@....de>,
        "Ardelean, Alexandru" <alexandru.Ardelean@...log.com>,
        "robh+dt@...nel.org" <robh+dt@...nel.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "Hennerich, Michael" <Michael.Hennerich@...log.com>,
        "linux-iio@...r.kernel.org" <linux-iio@...r.kernel.org>,
        "mark.rutland@....com" <mark.rutland@....com>,
        "pmeerw@...erw.net" <pmeerw@...erw.net>
Subject: Re: [PATCH v5 3/5] iio: amplifiers: hmc425a: Add support for HMC425A
 attenuator

Hi,

I checked the modifications and everything works as expected.

Thanks,
Ben
On Fri, 2020-02-14 at 14:09 +0000, Jonathan Cameron wrote:
> [External]
> 
> On Thu, 6 Feb 2020 17:11:47 +0200
> Beniamin Bia <beniamin.bia@...log.com> 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
> > 
> > Signed-off-by: Michael Hennerich <michael.hennerich@...log.com>
> > Signed-off-by: Alexandru Ardelean <alexandru.ardelean@...log.com>
> > Signed-off-by: Beniamin Bia <beniamin.bia@...log.com>
> 
> 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
> 
> > ---
> > Changes in v5:
> > -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
> > 
> > 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
> 
> I'll fix the no newline..
> 
> > diff --git a/drivers/iio/amplifiers/hmc425a.c
> > b/drivers/iio/amplifiers/hmc425a.c
> > new file mode 100644
> > index 000000000000..b0d624a7ad05
> > --- /dev/null
> > +++ b/drivers/iio/amplifiers/hmc425a.c
> > @@ -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");
> > +		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-
> > 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.
> 
> > +	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 <michael.hennerich@...log.com>");
> > +MODULE_DESCRIPTION("Analog Devices HMC425A and similar GPIO
> > control Gain Amplifiers");
> > +MODULE_LICENSE("GPL v2");
> 
> 

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