diff options
Diffstat (limited to 'drivers/iio/dac/mcp4821.c')
| -rw-r--r-- | drivers/iio/dac/mcp4821.c | 236 |
1 files changed, 236 insertions, 0 deletions
diff --git a/drivers/iio/dac/mcp4821.c b/drivers/iio/dac/mcp4821.c new file mode 100644 index 0000000000..8a0480d338 --- /dev/null +++ b/drivers/iio/dac/mcp4821.c @@ -0,0 +1,236 @@ +// 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/of.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"); |