Commit 1b791fad authored by Michael Welling's avatar Michael Welling Committed by Jonathan Cameron
Browse files

iio: dac: mcp4902/mcp4912/mcp4922 dac driver 



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

Signed-off-by: default avatarMichael Welling <mwelling@ieee.org>
Signed-off-by: default avatarJonathan Cameron <jic23@kernel.org>
parent 88f6da77

drivers/iio/dac/Kconfig

+10 −0
Original line number Diff line number Diff line
@@ -163,4 +163,14 @@ config MCP4725 
	  To compile this driver as a module, choose M here: the module

	  will be called mcp4725.



config MCP4922

	tristate "MCP4902, MCP4912, MCP4922 DAC driver"

	depends on SPI

	help

	  Say yes here to build the driver for the Microchip MCP4902

	  MCP4912, and MCP4922 DAC devices.



	  To compile this driver as a module, choose M here: the module

	  will be called mcp4922.



endmenu

drivers/iio/dac/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -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_MCP4922) += mcp4922.o

drivers/iio/dac/mcp4922.c

0 → 100644
+216 −0
Original line number Diff line number Diff line 
/*

 * mcp4922.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 MCP4922_NUM_CHANNELS	2



enum mcp4922_supported_device_ids {

	ID_MCP4902,

	ID_MCP4912,

	ID_MCP4922,

};



struct mcp4922_state {

	struct spi_device *spi;

	unsigned int value[MCP4922_NUM_CHANNELS];

	unsigned int vref_mv;

	struct regulator *vref_reg;

	u8 mosi[2] ____cacheline_aligned;

};



#define MCP4922_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 = {					\

		.sign = 'u',				\

		.realbits = (bits),			\

		.storagebits = 16,			\

		.shift = 12 - (bits),			\

	},						\

}



static int mcp4922_spi_write(struct mcp4922_state *state, u8 addr, u32 val)

{

	state->mosi[1] = val & 0xff;

	state->mosi[0] = (addr == 0) ? 0x00 : 0x80;

	state->mosi[0] |= 0x30 | ((val >> 8) & 0x0f);



	return spi_write(state->spi, state->mosi, 2);

}



static int mcp4922_read_raw(struct iio_dev *indio_dev,

		struct iio_chan_spec const *chan,

		int *val,

		int *val2,

		long mask)

{

	struct mcp4922_state *state = iio_priv(indio_dev);



	switch (mask) {

	case IIO_CHAN_INFO_RAW:

		*val = state->value[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 mcp4922_write_raw(struct iio_dev *indio_dev,

		struct iio_chan_spec const *chan,

		int val,

		int val2,

		long mask)

{

	struct mcp4922_state *state = iio_priv(indio_dev);



	if (val2 != 0)

		return -EINVAL;



	switch (mask) {

	case IIO_CHAN_INFO_RAW:

		if (val > GENMASK(chan->scan_type.realbits-1, 0))

			return -EINVAL;

		val <<= chan->scan_type.shift;

		state->value[chan->channel] = val;

		return mcp4922_spi_write(state, chan->channel, val);

	default:

		return -EINVAL;

	}

}



static const struct iio_chan_spec mcp4922_channels[3][MCP4922_NUM_CHANNELS] = {

	[ID_MCP4902] = { MCP4922_CHAN(0, 8),	MCP4922_CHAN(1, 8) },

	[ID_MCP4912] = { MCP4922_CHAN(0, 10),	MCP4922_CHAN(1, 10) },

	[ID_MCP4922] = { MCP4922_CHAN(0, 12),	MCP4922_CHAN(1, 12) },

};



static const struct iio_info mcp4922_info = {

	.read_raw = &mcp4922_read_raw,

	.write_raw = &mcp4922_write_raw,

	.driver_module = THIS_MODULE,

};



static int mcp4922_probe(struct spi_device *spi)

{

	struct iio_dev *indio_dev;

	struct mcp4922_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)) {

		dev_err(&spi->dev, "Vref regulator not specified\n");

		return PTR_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;



	spi_set_drvdata(spi, indio_dev);

	id = spi_get_device_id(spi);

	indio_dev->dev.parent = &spi->dev;

	indio_dev->info = &mcp4922_info;

	indio_dev->modes = INDIO_DIRECT_MODE;

	indio_dev->channels = mcp4922_channels[id->driver_data];

	indio_dev->num_channels = MCP4922_NUM_CHANNELS;

	indio_dev->name = id->name;



	ret = iio_device_register(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:

	regulator_disable(state->vref_reg);



	return ret;

}



static int mcp4922_remove(struct spi_device *spi)

{

	struct iio_dev *indio_dev = spi_get_drvdata(spi);

	struct mcp4922_state *state;



	iio_device_unregister(indio_dev);

	state = iio_priv(indio_dev);

	regulator_disable(state->vref_reg);



	return 0;

}



static const struct spi_device_id mcp4922_id[] = {

	{"mcp4902", ID_MCP4902},

	{"mcp4912", ID_MCP4912},

	{"mcp4922", ID_MCP4922},

	{}

};

MODULE_DEVICE_TABLE(spi, mcp4922_id);



static struct spi_driver mcp4922_driver = {

	.driver = {

		   .name = "mcp4922",

		   .owner = THIS_MODULE,

		   },

	.probe = mcp4922_probe,

	.remove = mcp4922_remove,

	.id_table = mcp4922_id,

};

module_spi_driver(mcp4922_driver);



MODULE_AUTHOR("Michael Welling <mwelling@ieee.org>");

MODULE_DESCRIPTION("Microchip MCP4902, MCP4912, MCP4922 DAC");

MODULE_LICENSE("GPL v2");