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/*
* 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");
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