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iio: dac: mcp4902/mcp4912/mcp4922 dac driver
This patch provides an iio device driver for the Microchip MCP49x2 series DACs. Signed-off-by: Michael Welling <mwelling@ieee.org> Signed-off-by: Jonathan Cameron <jic23@kernel.org>
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Michael Welling
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Jonathan Cameron
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Jun 21, 2014
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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. | ||
* | ||
*/ | ||
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#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> | ||
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#define MCP4922_NUM_CHANNELS 2 | ||
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enum mcp4922_supported_device_ids { | ||
ID_MCP4902, | ||
ID_MCP4912, | ||
ID_MCP4922, | ||
}; | ||
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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; | ||
}; | ||
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#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), \ | ||
}, \ | ||
} | ||
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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); | ||
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return spi_write(state->spi, state->mosi, 2); | ||
} | ||
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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); | ||
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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; | ||
} | ||
} | ||
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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); | ||
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if (val2 != 0) | ||
return -EINVAL; | ||
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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; | ||
} | ||
} | ||
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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) }, | ||
}; | ||
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static const struct iio_info mcp4922_info = { | ||
.read_raw = &mcp4922_read_raw, | ||
.write_raw = &mcp4922_write_raw, | ||
.driver_module = THIS_MODULE, | ||
}; | ||
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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; | ||
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indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*state)); | ||
if (indio_dev == NULL) | ||
return -ENOMEM; | ||
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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); | ||
} | ||
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ret = regulator_enable(state->vref_reg); | ||
if (ret) { | ||
dev_err(&spi->dev, "Failed to enable vref regulator: %d\n", | ||
ret); | ||
return ret; | ||
} | ||
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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; | ||
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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; | ||
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ret = iio_device_register(indio_dev); | ||
if (ret) { | ||
dev_err(&spi->dev, "Failed to register iio device: %d\n", | ||
ret); | ||
goto error_disable_reg; | ||
} | ||
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return 0; | ||
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error_disable_reg: | ||
regulator_disable(state->vref_reg); | ||
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return ret; | ||
} | ||
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static int mcp4922_remove(struct spi_device *spi) | ||
{ | ||
struct iio_dev *indio_dev = spi_get_drvdata(spi); | ||
struct mcp4922_state *state; | ||
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iio_device_unregister(indio_dev); | ||
state = iio_priv(indio_dev); | ||
regulator_disable(state->vref_reg); | ||
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return 0; | ||
} | ||
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static const struct spi_device_id mcp4922_id[] = { | ||
{"mcp4902", ID_MCP4902}, | ||
{"mcp4912", ID_MCP4912}, | ||
{"mcp4922", ID_MCP4922}, | ||
{} | ||
}; | ||
MODULE_DEVICE_TABLE(spi, mcp4922_id); | ||
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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); | ||
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MODULE_AUTHOR("Michael Welling <mwelling@ieee.org>"); | ||
MODULE_DESCRIPTION("Microchip MCP4902, MCP4912, MCP4922 DAC"); | ||
MODULE_LICENSE("GPL v2"); |