Re: [PATCH v2] iio: dac: mcp4902/mcp4912/mcp4922 dac driver

[Peter Meerwald]

> This patch provides an iio device driver for the Microchip
> MCP49x2 series DACs.

comments inline
 
> Signed-off-by: Michael Welling <mwelling@xxxxxxxx>
> ---
>  drivers/iio/dac/Kconfig   |   10 +++
>  drivers/iio/dac/Makefile  |    1 +
>  drivers/iio/dac/mcp49x2.c |  213 +++++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 224 insertions(+)
>  create mode 100644 drivers/iio/dac/mcp49x2.c
> 
> diff --git a/drivers/iio/dac/Kconfig b/drivers/iio/dac/Kconfig
> index f378ca8..032d678 100644
> --- a/drivers/iio/dac/Kconfig
> +++ b/drivers/iio/dac/Kconfig
> @@ -163,4 +163,14 @@ config MCP4725
>  	  To compile this driver as a module, choose M here: the module
>  	  will be called mcp4725.
>  
> +config MCP49X2
> +	tristate "MCP4902, MCP4912, MCP4922 DAC driver"
> +	depends on SPI
> +	---help---
> +	  Say yes here to build the driver for the Microchip MCP49x2
> +	  series DAC devices.
> +
> +	  To compile this driver as a module, choose M here: the module
> +	  will be called mcp49x2.
> +
>  endmenu
> diff --git a/drivers/iio/dac/Makefile b/drivers/iio/dac/Makefile
> index bb84ad6..2fdfc2e 100644
> --- a/drivers/iio/dac/Makefile
> +++ b/drivers/iio/dac/Makefile
> @@ -18,3 +18,4 @@ obj-$(CONFIG_AD5686) += ad5686.o
>  obj-$(CONFIG_AD7303) += ad7303.o
>  obj-$(CONFIG_MAX517) += max517.o
>  obj-$(CONFIG_MCP4725) += mcp4725.o
> +obj-$(CONFIG_MCP49X2) += mcp49x2.o
> diff --git a/drivers/iio/dac/mcp49x2.c b/drivers/iio/dac/mcp49x2.c
> new file mode 100644
> index 0000000..f90a83a
> --- /dev/null
> +++ b/drivers/iio/dac/mcp49x2.c
> @@ -0,0 +1,213 @@
> +/*
> + * mcp49x2.c
> + *
> + * Driver for Microchip Digital to Analog Converters.
> + * Supports MCP4902, MCP4912, and MCP4922.
> + *
> + * Copyright (c) 2014 EMAC Inc.
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License as published by
> + * the Free Software Foundation; either version 2 of the License, or
> + * (at your option) any later version.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> + * GNU General Public License for more details.
> + *
> + */
> +
> +#include <linux/module.h>
> +#include <linux/init.h>
> +#include <linux/spi/spi.h>
> +#include <linux/iio/iio.h>
> +#include <linux/iio/sysfs.h>
> +#include <linux/regulator/consumer.h>
> +#include <linux/bitops.h>
> +
> +#define	MCP49X2_RES_MASK(x)	GENMASK(x, 0)

MCP49X2_RES_MASK() could go away
it should be GENMASK(x-1, 0)

> +#define MCP49X2_NUM_CHANNELS	2
> +
> +enum mcp49x2_supported_device_ids {
> +	ID_MCP4902,
> +	ID_MCP4912,
> +	ID_MCP4922,
> +};
> +
> +struct mcp49x2_state {
> +	struct spi_device *spi;
> +	unsigned int value[MCP49X2_NUM_CHANNELS];
> +	unsigned int power_mode[MCP49X2_NUM_CHANNELS];
> +	unsigned int vref_mv;
> +	struct regulator *vref_reg;
> +};
> +
> +#define MCP49X2_CHAN(chan, bits) {			\
> +	.type = IIO_VOLTAGE,				\
> +	.output = 1,					\
> +	.indexed = 1,					\
> +	.channel = chan,				\
> +	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),	\
> +	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),	\
> +	.scan_type = IIO_ST('u', bits, 16, 12-bits),	\
> +}
> +
> +static int mcp49x2_spi_write(struct spi_device *spi, u8 addr, u32 val)
> +{
> +	u8 mosi[2] ____cacheline_aligned;
> +
> +	mosi[1] = val & 0xff;
> +	mosi[0] = (addr == 0) ? 0x00: 0x80;
> +	mosi[0] |= 0x30 | ((val >> 8) & 0x0f);
> +
> +	return spi_write(spi, mosi, 2);
> +}
> +
> +static int mcp49x2_read_raw(struct iio_dev *indio_dev,
> +		struct iio_chan_spec const *chan,
> +		int *val,
> +		int *val2,
> +		long mask)
> +{
> +	struct mcp49x2_state *state = iio_priv(indio_dev);
> +
> +	switch (mask) {
> +	case IIO_CHAN_INFO_RAW:
> +		*val = state->value[chan->address];

address is gone, use chan->channel

> +		return IIO_VAL_INT;
> +	case IIO_CHAN_INFO_SCALE:
> +		*val = state->vref_mv;
> +		*val2 = chan->scan_type.realbits;
> +		return IIO_VAL_FRACTIONAL_LOG2;
> +	default:
> +		return -EINVAL;
> +	}
> +}
> +
> +static int mcp49x2_write_raw(struct iio_dev *indio_dev,
> +		struct iio_chan_spec const *chan,
> +		int val,
> +		int val2,
> +		long mask)
> +{
> +	struct mcp49x2_state *state = iio_priv(indio_dev);
> +
> +	switch (mask) {
> +	case IIO_CHAN_INFO_RAW:
> +		if (val > MCP49X2_RES_MASK(chan->scan_type.realbits))
> +			return -EINVAL;
> +		val <<= chan->scan_type.shift;
> +		state->value[chan->address] = val;

use chan->channel

> +		return mcp49x2_spi_write(state->spi, chan->address, val);
> +	default:
> +		return -EINVAL;
> +	}
> +}
> +
> +static const struct iio_chan_spec mcp49x2_channels[3][MCP49X2_NUM_CHANNELS] = {
> +	[ID_MCP4902] = { MCP49X2_CHAN(0, 8),	MCP49X2_CHAN(1, 8) },
> +	[ID_MCP4912] = { MCP49X2_CHAN(0, 10),	MCP49X2_CHAN(1, 10) },
> +	[ID_MCP4922] = { MCP49X2_CHAN(0, 12),	MCP49X2_CHAN(1, 12) },
> +};
> +
> +static const struct iio_info mcp49x2_info = {
> +	.read_raw = &mcp49x2_read_raw,
> +	.write_raw = &mcp49x2_write_raw,
> +	.driver_module = THIS_MODULE,
> +};
> +
> +static int mcp49x2_probe(struct spi_device *spi)
> +{
> +	struct iio_dev *indio_dev;
> +	struct mcp49x2_state *state;
> +	const struct spi_device_id *id;
> +	int ret;
> +
> +	indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*state));
> +	if (indio_dev == NULL)
> +		return -ENOMEM;
> +
> +	state = iio_priv(indio_dev);
> +	state->spi = spi;
> +	state->vref_reg = devm_regulator_get(&spi->dev, "vref");
> +	if (!IS_ERR(state->vref_reg)) {
> +		ret = regulator_enable(state->vref_reg);
> +		if (ret) {
> +			dev_err(&spi->dev, "Failed to enable vref regulator: %d\n",
> +				ret);
> +			return ret;
> +		}
> +
> +		ret = regulator_get_voltage(state->vref_reg);
> +		if (ret < 0) {
> +			dev_err(&spi->dev, "Failed to read vref regulator: %d\n",
> +				ret);
> +			goto error_disable_reg;
> +		}
> +		state->vref_mv = ret / 1000;
> +	} else {
> +		dev_info(&spi->dev, "Vref regulator not specified assuming 2.5V\n");
> +		state->vref_mv = 2500;
> +	}
> +
> +	spi_set_drvdata(spi, indio_dev);
> +	id = spi_get_device_id(spi);
> +	indio_dev->dev.parent = &spi->dev;
> +	indio_dev->info = &mcp49x2_info;
> +	indio_dev->modes = INDIO_DIRECT_MODE;
> +	indio_dev->channels = mcp49x2_channels[id->driver_data];
> +	indio_dev->num_channels = MCP49X2_NUM_CHANNELS;
> +	indio_dev->name = id->name;
> +
> +	ret = devm_iio_device_register(&spi->dev, indio_dev);
> +	if (ret) {
> +		dev_err(&spi->dev, "Failed to register iio device: %d\n",
> +				ret);
> +		goto error_disable_reg;
> +	}
> +
> +	return 0;
> +
> +error_disable_reg:
> +	if (!IS_ERR(state->vref_reg))
> +		regulator_disable(state->vref_reg);
> +
> +	return ret;
> +}
> +
> +static int mcp49x2_remove(struct spi_device *spi)
> +{
> +	struct iio_dev *indio_dev = spi_get_drvdata(spi);
> +	struct mcp49x2_state *state;
> +
> +	state = iio_priv(indio_dev);
> +
> +	if (!IS_ERR(state->vref_reg))
> +		regulator_disable(state->vref_reg);
> +
> +	return 0;
> +}
> +
> +static const struct spi_device_id mcp49x2_id[] = {
> +	{"mcp4902", ID_MCP4902},
> +	{"mcp4912", ID_MCP4912},
> +	{"mcp4922", ID_MCP4922},
> +	{}
> +};
> +MODULE_DEVICE_TABLE(spi, mcp49x2_id);
> +
> +static struct spi_driver mcp49x2_driver = {
> +	.driver = {
> +		   .name = "mcp49x2",
> +		   .owner = THIS_MODULE,
> +		   },
> +	.probe = mcp49x2_probe,
> +	.remove = mcp49x2_remove,
> +	.id_table = mcp49x2_id,
> +};
> +module_spi_driver(mcp49x2_driver);
> +
> +MODULE_AUTHOR("Michael Welling <mwelling@xxxxxxxx>");
> +MODULE_DESCRIPTION("Microchip MCP4902, MCP4912, MCP4922 DAC");
> +MODULE_LICENSE("GPL v2");
> 

-- 

Peter Meerwald
+43-664-2444418 (mobile)
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