diff options
Diffstat (limited to 'drivers/iio/dac/mcp4922.c')
| -rw-r--r-- | drivers/iio/dac/mcp4922.c | 219 |
1 files changed, 219 insertions, 0 deletions
diff --git a/drivers/iio/dac/mcp4922.c b/drivers/iio/dac/mcp4922.c new file mode 100644 index 000000000..b5190d1da --- /dev/null +++ b/drivers/iio/dac/mcp4922.c @@ -0,0 +1,219 @@ +/* + * 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); + int ret; + + if (val2 != 0) + return -EINVAL; + + switch (mask) { + case IIO_CHAN_INFO_RAW: + if (val < 0 || val > GENMASK(chan->scan_type.realbits - 1, 0)) + return -EINVAL; + val <<= chan->scan_type.shift; + + ret = mcp4922_spi_write(state, chan->channel, val); + if (!ret) + state->value[chan->channel] = val; + return ret; + + 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, +}; + +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", + }, + .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"); |