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// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Copyright (C) 2023 Anshul Dalal <anshulusr@gmail.com>
*
* Driver for Microchip MCP4801, MCP4802, MCP4811, MCP4812, MCP4821 and MCP4822
*
* Based on the work of:
* Michael Welling (MCP4922 Driver)
*
* Datasheet:
* MCP48x1: https://ww1.microchip.com/downloads/en/DeviceDoc/22244B.pdf
* MCP48x2: https://ww1.microchip.com/downloads/en/DeviceDoc/20002249B.pdf
*
* TODO:
* - Configurable gain
* - Regulator control
*/
#include <linux/module.h>
#include <linux/mod_devicetable.h>
#include <linux/spi/spi.h>
#include <linux/iio/iio.h>
#include <linux/iio/types.h>
#include <asm/unaligned.h>
#define MCP4821_ACTIVE_MODE BIT(12)
#define MCP4802_SECOND_CHAN BIT(15)
/* DAC uses an internal Voltage reference of 4.096V at a gain of 2x */
#define MCP4821_2X_GAIN_VREF_MV 4096
enum mcp4821_supported_drvice_ids {
ID_MCP4801,
ID_MCP4802,
ID_MCP4811,
ID_MCP4812,
ID_MCP4821,
ID_MCP4822,
};
struct mcp4821_state {
struct spi_device *spi;
u16 dac_value[2];
};
struct mcp4821_chip_info {
const char *name;
int num_channels;
const struct iio_chan_spec channels[2];
};
#define MCP4821_CHAN(channel_id, resolution) \
{ \
.type = IIO_VOLTAGE, .output = 1, .indexed = 1, \
.channel = (channel_id), \
.info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \
.scan_type = { \
.realbits = (resolution), \
.shift = 12 - (resolution), \
}, \
}
static const struct mcp4821_chip_info mcp4821_chip_info_table[6] = {
[ID_MCP4801] = {
.name = "mcp4801",
.num_channels = 1,
.channels = {
MCP4821_CHAN(0, 8),
},
},
[ID_MCP4802] = {
.name = "mcp4802",
.num_channels = 2,
.channels = {
MCP4821_CHAN(0, 8),
MCP4821_CHAN(1, 8),
},
},
[ID_MCP4811] = {
.name = "mcp4811",
.num_channels = 1,
.channels = {
MCP4821_CHAN(0, 10),
},
},
[ID_MCP4812] = {
.name = "mcp4812",
.num_channels = 2,
.channels = {
MCP4821_CHAN(0, 10),
MCP4821_CHAN(1, 10),
},
},
[ID_MCP4821] = {
.name = "mcp4821",
.num_channels = 1,
.channels = {
MCP4821_CHAN(0, 12),
},
},
[ID_MCP4822] = {
.name = "mcp4822",
.num_channels = 2,
.channels = {
MCP4821_CHAN(0, 12),
MCP4821_CHAN(1, 12),
},
},
};
static int mcp4821_read_raw(struct iio_dev *indio_dev,
struct iio_chan_spec const *chan, int *val,
int *val2, long mask)
{
struct mcp4821_state *state;
switch (mask) {
case IIO_CHAN_INFO_RAW:
state = iio_priv(indio_dev);
*val = state->dac_value[chan->channel];
return IIO_VAL_INT;
case IIO_CHAN_INFO_SCALE:
*val = MCP4821_2X_GAIN_VREF_MV;
*val2 = chan->scan_type.realbits;
return IIO_VAL_FRACTIONAL_LOG2;
default:
return -EINVAL;
}
}
static int mcp4821_write_raw(struct iio_dev *indio_dev,
struct iio_chan_spec const *chan, int val,
int val2, long mask)
{
struct mcp4821_state *state = iio_priv(indio_dev);
u16 write_val;
__be16 write_buffer;
int ret;
if (val2 != 0)
return -EINVAL;
if (val < 0 || val >= BIT(chan->scan_type.realbits))
return -EINVAL;
if (mask != IIO_CHAN_INFO_RAW)
return -EINVAL;
write_val = MCP4821_ACTIVE_MODE | val << chan->scan_type.shift;
if (chan->channel)
write_val |= MCP4802_SECOND_CHAN;
write_buffer = cpu_to_be16(write_val);
ret = spi_write(state->spi, &write_buffer, sizeof(write_buffer));
if (ret) {
dev_err(&state->spi->dev, "Failed to write to device: %d", ret);
return ret;
}
state->dac_value[chan->channel] = val;
return 0;
}
static const struct iio_info mcp4821_info = {
.read_raw = &mcp4821_read_raw,
.write_raw = &mcp4821_write_raw,
};
static int mcp4821_probe(struct spi_device *spi)
{
struct iio_dev *indio_dev;
struct mcp4821_state *state;
const struct mcp4821_chip_info *info;
indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*state));
if (indio_dev == NULL)
return -ENOMEM;
state = iio_priv(indio_dev);
state->spi = spi;
info = spi_get_device_match_data(spi);
indio_dev->name = info->name;
indio_dev->info = &mcp4821_info;
indio_dev->modes = INDIO_DIRECT_MODE;
indio_dev->channels = info->channels;
indio_dev->num_channels = info->num_channels;
return devm_iio_device_register(&spi->dev, indio_dev);
}
#define MCP4821_COMPATIBLE(of_compatible, id) \
{ \
.compatible = of_compatible, \
.data = &mcp4821_chip_info_table[id] \
}
static const struct of_device_id mcp4821_of_table[] = {
MCP4821_COMPATIBLE("microchip,mcp4801", ID_MCP4801),
MCP4821_COMPATIBLE("microchip,mcp4802", ID_MCP4802),
MCP4821_COMPATIBLE("microchip,mcp4811", ID_MCP4811),
MCP4821_COMPATIBLE("microchip,mcp4812", ID_MCP4812),
MCP4821_COMPATIBLE("microchip,mcp4821", ID_MCP4821),
MCP4821_COMPATIBLE("microchip,mcp4822", ID_MCP4822),
{ /* Sentinel */ }
};
MODULE_DEVICE_TABLE(of, mcp4821_of_table);
static const struct spi_device_id mcp4821_id_table[] = {
{ "mcp4801", (kernel_ulong_t)&mcp4821_chip_info_table[ID_MCP4801]},
{ "mcp4802", (kernel_ulong_t)&mcp4821_chip_info_table[ID_MCP4802]},
{ "mcp4811", (kernel_ulong_t)&mcp4821_chip_info_table[ID_MCP4811]},
{ "mcp4812", (kernel_ulong_t)&mcp4821_chip_info_table[ID_MCP4812]},
{ "mcp4821", (kernel_ulong_t)&mcp4821_chip_info_table[ID_MCP4821]},
{ "mcp4822", (kernel_ulong_t)&mcp4821_chip_info_table[ID_MCP4822]},
{ /* Sentinel */ }
};
MODULE_DEVICE_TABLE(spi, mcp4821_id_table);
static struct spi_driver mcp4821_driver = {
.driver = {
.name = "mcp4821",
.of_match_table = mcp4821_of_table,
},
.probe = mcp4821_probe,
.id_table = mcp4821_id_table,
};
module_spi_driver(mcp4821_driver);
MODULE_AUTHOR("Anshul Dalal <anshulusr@gmail.com>");
MODULE_DESCRIPTION("Microchip MCP4821 DAC Driver");
MODULE_LICENSE("GPL");
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