> This patch provides an iio device driver for the Microchip
> MCP49x2 series DACs.
comments inline
> Signed-off-by: Michael Welling <mwelling@xxxxxxxx>
> ---
> drivers/iio/dac/Kconfig | 10 +++
> drivers/iio/dac/Makefile | 1 +
> drivers/iio/dac/mcp49x2.c | 215 +++++++++++++++++++++++++++++++++++++++++++++
> 3 files changed, 226 insertions(+)
> create mode 100644 drivers/iio/dac/mcp49x2.c
>
> diff --git a/drivers/iio/dac/Kconfig b/drivers/iio/dac/Kconfig
> index f378ca8..032d678 100644
> --- a/drivers/iio/dac/Kconfig
> +++ b/drivers/iio/dac/Kconfig
> @@ -163,4 +163,14 @@ config MCP4725
> To compile this driver as a module, choose M here: the module
> will be called mcp4725.
>
> +config MCP49X2
> + tristate "MCP4902, MCP4912, MCP4922 DAC driver"
> + depends on SPI
> + ---help---
> + Say yes here to build the driver for the Microchip MCP49x2
> + series DAC devices.
> +
> + To compile this driver as a module, choose M here: the module
> + will be called mcp49x2.
> +
> endmenu
> diff --git a/drivers/iio/dac/Makefile b/drivers/iio/dac/Makefile
> index bb84ad6..2fdfc2e 100644
> --- a/drivers/iio/dac/Makefile
> +++ b/drivers/iio/dac/Makefile
> @@ -18,3 +18,4 @@ obj-$(CONFIG_AD5686) += ad5686.o
> obj-$(CONFIG_AD7303) += ad7303.o
> obj-$(CONFIG_MAX517) += max517.o
> obj-$(CONFIG_MCP4725) += mcp4725.o
> +obj-$(CONFIG_MCP49X2) += mcp49x2.o
> diff --git a/drivers/iio/dac/mcp49x2.c b/drivers/iio/dac/mcp49x2.c
> new file mode 100644
> index 0000000..0375046
> --- /dev/null
> +++ b/drivers/iio/dac/mcp49x2.c
> @@ -0,0 +1,215 @@
> +/*
> + * mcp49x2.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>
> +
> +#define MCP49X2_RES_MASK(x) ((1 << (x)) - 1)
use GENMASK() in linux/bitops.h
> +
> +enum mcp49x2_supported_device_ids {
> + ID_MCP4902,
> + ID_MCP4912,
> + ID_MCP4922,
> +};
> +
> +struct mcp49x2_state {
> + struct spi_device *spi;
> + unsigned int value[2];
> + unsigned int power_mode[2];
> + unsigned int vref_mv;
> + struct regulator *vref_reg;
> +};
> +
> +#define MCP49X2_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), \
> + .address = chan, \
could use .channel instead of .address
> + .scan_type = IIO_ST('u', bits, 16, 12-(bits)), \
consistently put macro arguments in () or don't
> + .ext_info = NULL, \
no need to set ext_info
> +}
> +
> +static int mcp49x2_spi_write(struct spi_device *spi, u8 addr, u32 val)
> +{
> + u8 mosi[2];
> +
> + mosi[1] = val & 0xff;
> + mosi[0] = (addr == 0) ? 0x00 : 0x80;
> + mosi[0] |= 0x30 | ((val >> 8) & 0x0f);
> +
> + return spi_write(spi, mosi, 2);
SPI buffers need to be cacheline aligned?
> +}
> +
> +static int mcp49x2_read_raw(struct iio_dev *indio_dev,
> + struct iio_chan_spec const *chan,
> + int *val,
> + int *val2,
> + long mask)
> +{
> + struct mcp49x2_state *state = iio_priv(indio_dev);
> +
> + if (chan->address >= 2)
> + return -EINVAL;
no need to check the address; you are relying on chan being valid anyway
> +
> + switch (mask) {
> + case IIO_CHAN_INFO_RAW:
> + *val = state->value[chan->address];
> + 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 mcp49x2_write_raw(struct iio_dev *indio_dev,
> + struct iio_chan_spec const *chan,
> + int val,
> + int val2,
> + long mask)
> +{
> + struct mcp49x2_state *state = iio_priv(indio_dev);
> +
> + if (chan->address >= 2)
> + return -EINVAL;
> +
> + switch (mask) {
> + case IIO_CHAN_INFO_RAW:
maybe check the range of val and report EINVAL if out of range?
this silently makes val fit, no matter what
> + val &= MCP49X2_RES_MASK(chan->scan_type.realbits);
> + val <<= chan->scan_type.shift;
> + state->value[chan->address] = val;
> + return mcp49x2_spi_write(state->spi, chan->address, val);
> + default:
> + return -EINVAL;
> + }
> +}
> +
> +static const struct iio_chan_spec mcp49x2_channels[3][2] = {
> + [ID_MCP4902] = { MCP49X2_CHAN(0, 8), MCP49X2_CHAN(1, 8) },
> + [ID_MCP4912] = { MCP49X2_CHAN(0, 10), MCP49X2_CHAN(1, 10) },
> + [ID_MCP4922] = { MCP49X2_CHAN(0, 12), MCP49X2_CHAN(1, 12) },
> +};
> +
> +static const struct iio_info mcp49x2_info = {
> + .read_raw = &mcp49x2_read_raw,
> + .write_raw = &mcp49x2_write_raw,
> + .driver_module = THIS_MODULE,
> +};
> +
> +static int mcp49x2_probe(struct spi_device *spi)
> +{
> + struct iio_dev *indio_dev;
> + struct mcp49x2_state *state;
> + const struct spi_device_id *id;
> + int ret;
> +
> + indio_dev = iio_device_alloc(sizeof(*state));
devm_iio_device_alloc()
> + 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)) {
> + ret = regulator_enable(state->vref_reg);
> + if (ret) {
> + dev_err(dev, "Failed to enable vref regulator: %d\n",
> + ret);
> + goto error_free;
> + }
> +
> + ret = regulator_get_voltage(state->vref_reg);
> + if (ret < 0)
> + goto error_disable_reg;
> +
> + state->vref_mv = ret / 1000;
> + } else {
> + dev_info(dev, "Vref regulator not specified assuming 2.5V\n");
> + state->vref_mv = 2500;
> + }
> +
> + spi_set_drvdata(spi, indio_dev);
> + id = spi_get_device_id(spi);
> + indio_dev->dev.parent = &spi->dev;
> + indio_dev->info = &mcp49x2_info;
> + indio_dev->modes = INDIO_DIRECT_MODE;
> + indio_dev->channels = mcp49x2_channels[id->driver_data];
> + indio_dev->num_channels = 2;
maybe use a constant for the number of channels here and also
when declaring mcp49x2_channels[3][2]
> + indio_dev->name = id->name;
> +
> + ret = iio_device_register(indio_dev);
use devm_iio_device_register()
drop newline
> +
> + if (ret) {
> + dev_err(dev, "Failed to register iio device: %d\n",
> + ret);
> + goto error_disable_reg;
> + }
> +
> + return 0;
> +
> +error_disable_reg:
> + if (!IS_ERR(state->vref_reg))
> + regulator_disable(state->vref_reg);
> +error_free:
> + iio_device_free(indio_dev);
> +
> + return ret;
> +}
> +
> +static int mcp49x2_remove(struct spi_device *spi)
> +{
> + struct iio_dev *indio_dev = spi_get_drvdata(spi);
> +
iio_device_unregister()?
but should go away with devm_ stuff
> + iio_device_free(indio_dev);
> + return 0;
> +}
> +
> +static const struct spi_device_id mcp49x2_id[] = {
> + {"mcp4902", ID_MCP4902},
> + {"mcp4912", ID_MCP4912},
> + {"mcp4922", ID_MCP4922},
> + {}
> +};
> +MODULE_DEVICE_TABLE(spi, mcp49x2_id);
> +
> +static struct spi_driver mcp49x2_driver = {
> + .driver = {
> + .name = "mcp49x2",
> + .owner = THIS_MODULE,
> + },
> + .probe = mcp49x2_probe,
> + .remove = mcp49x2_remove,
> + .id_table = mcp49x2_id,
> +};
> +module_spi_driver(mcp49x2_driver);
> +
> +MODULE_AUTHOR("Michael Welling <mwelling@xxxxxxxx>");
> +MODULE_DESCRIPTION("Microchip MCP4902, MCP4912, MCP4922 DAC");
> +MODULE_LICENSE("GPL v2");
>
--
Peter Meerwald
+43-664-2444418 (mobile)
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