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>

3 files changed, 227 insertions, 0 deletions

diff --git a/drivers/iio/dac/Kconfig b/drivers/iio/dac/Kconfig
index f378ca8033db..f278eff42a4c 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 MCP4922
+        tristate "MCP4902, MCP4912, MCP4922 DAC driver"
+        depends on SPI
+        help
+          Say yes here to build the driver for the Microchip MCP4902
+          MCP4912, and MCP4922 DAC devices.
+
+          To compile this driver as a module, choose M here: the module
+          will be called mcp4922.
+
 endmenu
diff --git a/drivers/iio/dac/Makefile b/drivers/iio/dac/Makefile
index bb84ad64463f..10107640bb46 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_MCP4922) += mcp4922.o
diff --git a/drivers/iio/dac/mcp4922.c b/drivers/iio/dac/mcp4922.c
new file mode 100644
index 000000000000..92cf4ca6981d
--- /dev/null
+++ b/drivers/iio/dac/mcp4922.c
@@ -0,0 +1,216 @@
+/*
+ * 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);
+
+        if (val2 != 0)
+                return -EINVAL;
+
+        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;
+        }
+}
+
+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,
+        .driver_module = THIS_MODULE,
+};
+
+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",
+                   .owner = THIS_MODULE,
+                   },
+        .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");