iio: add m62332 DAC driver

m62332 is a simple 2-channel DAC used on several Sharp Zaurus boards to
control LCD voltage, backlight and sound. The driver use regulators to
control the reference voltage and enabling/disabling the DAC.

Signed-off-by: Dmitry Eremin-Solenikov <dbaryshkov@gmail.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

3 files changed, 280 insertions, 0 deletions

diff --git a/drivers/iio/dac/Kconfig b/drivers/iio/dac/Kconfig
index 13471a76e5bf..e701e28fb1cd 100644
--- a/drivers/iio/dac/Kconfig
+++ b/drivers/iio/dac/Kconfig
@@ -142,6 +142,16 @@ config AD7303
           To compile this driver as module choose M here: the module will be called
           ad7303.
 
+config M62332
+        tristate "Mitsubishi M62332 DAC driver"
+        depends on I2C
+        help
+          If you say yes here you get support for the Mitsubishi M62332
+          (I2C 8-Bit DACs with rail-to-rail outputs).
+
+          This driver can also be built as a module.  If so, the module
+          will be called m62332.
+
 config MAX517
         tristate "Maxim MAX517/518/519/520/521 DAC driver"
         depends on I2C
diff --git a/drivers/iio/dac/Makefile b/drivers/iio/dac/Makefile
index 52be7e1acf16..63ae05633e0c 100644
--- a/drivers/iio/dac/Makefile
+++ b/drivers/iio/dac/Makefile
@@ -16,6 +16,7 @@ obj-$(CONFIG_AD5764) += ad5764.o
 obj-$(CONFIG_AD5791) += ad5791.o
 obj-$(CONFIG_AD5686) += ad5686.o
 obj-$(CONFIG_AD7303) += ad7303.o
+obj-$(CONFIG_M62332) += m62332.o
 obj-$(CONFIG_MAX517) += max517.o
 obj-$(CONFIG_MAX5821) += max5821.o
 obj-$(CONFIG_MCP4725) += mcp4725.o
diff --git a/drivers/iio/dac/m62332.c b/drivers/iio/dac/m62332.c
new file mode 100644
index 000000000000..c23d7fa889ee
--- /dev/null
+++ b/drivers/iio/dac/m62332.c
@@ -0,0 +1,269 @@
+/*
+ *  m62332.c - Support for Mitsubishi m62332 DAC
+ *
+ *  Copyright (c) 2014 Dmitry Eremin-Solenikov
+ *
+ *  Based on max517 driver:
+ *  Copyright (C) 2010, 2011 Roland Stigge <stigge@antcom.de>
+ *
+ *  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/slab.h>
+#include <linux/i2c.h>
+#include <linux/err.h>
+
+#include <linux/iio/iio.h>
+#include <linux/iio/driver.h>
+
+#include <linux/regulator/consumer.h>
+
+#define M62332_CHANNELS 2
+
+struct m62332_data {
+        struct i2c_client       *client;
+        u16                     vref_mv;
+        struct regulator        *vcc;
+        struct mutex            mutex;
+        u8                      raw[M62332_CHANNELS];
+#ifdef CONFIG_PM_SLEEP
+        u8                      save[M62332_CHANNELS];
+#endif
+};
+
+static int m62332_set_value(struct iio_dev *indio_dev,
+        u8 val, int channel)
+{
+        struct m62332_data *data = iio_priv(indio_dev);
+        struct i2c_client *client = data->client;
+        u8 outbuf[2];
+        int res;
+
+        if (val == data->raw[channel])
+                return 0;
+
+        outbuf[0] = channel;
+        outbuf[1] = val;
+
+        mutex_lock(&data->mutex);
+
+        if (val) {
+                res = regulator_enable(data->vcc);
+                if (res)
+                        goto out;
+        }
+
+        res = i2c_master_send(client, outbuf, 2);
+        if (res >= 0 && res != 2)
+                res = -EIO;
+        if (res < 0)
+                goto out;
+
+        data->raw[channel] = val;
+
+        if (!val)
+                regulator_disable(data->vcc);
+
+        mutex_unlock(&data->mutex);
+
+        return 0;
+
+out:
+        mutex_unlock(&data->mutex);
+
+        return res;
+}
+
+static int m62332_read_raw(struct iio_dev *indio_dev,
+                           struct iio_chan_spec const *chan,
+                           int *val,
+                           int *val2,
+                           long m)
+{
+        struct m62332_data *data = iio_priv(indio_dev);
+
+        switch (m) {
+        case IIO_CHAN_INFO_SCALE:
+                /* Corresponds to Vref / 2^(bits) */
+                *val = data->vref_mv;
+                *val2 = 8;
+                return IIO_VAL_FRACTIONAL_LOG2;
+        case IIO_CHAN_INFO_RAW:
+                *val = data->raw[chan->channel];
+                return IIO_VAL_INT;
+        case IIO_CHAN_INFO_OFFSET:
+                *val = 1;
+                return IIO_VAL_INT;
+        default:
+                break;
+        }
+        return -EINVAL;
+}
+
+static int m62332_write_raw(struct iio_dev *indio_dev,
+        struct iio_chan_spec const *chan, int val, int val2, long mask)
+{
+        int ret;
+
+        switch (mask) {
+        case IIO_CHAN_INFO_RAW:
+                if (val < 0 || val > 255)
+                        return -EINVAL;
+
+                ret = m62332_set_value(indio_dev, val, chan->channel);
+                break;
+        default:
+                ret = -EINVAL;
+                break;
+        }
+
+        return ret;
+}
+
+#ifdef CONFIG_PM_SLEEP
+static int m62332_suspend(struct device *dev)
+{
+        struct i2c_client *client = to_i2c_client(dev);
+        struct iio_dev *indio_dev = i2c_get_clientdata(client);
+        struct m62332_data *data = iio_priv(indio_dev);
+        int ret;
+
+        data->save[0] = data->raw[0];
+        data->save[1] = data->raw[1];
+
+        ret = m62332_set_value(indio_dev, 0, 0);
+        if (ret < 0)
+                return ret;
+
+        return m62332_set_value(indio_dev, 0, 1);
+}
+
+static int m62332_resume(struct device *dev)
+{
+        struct i2c_client *client = to_i2c_client(dev);
+        struct iio_dev *indio_dev = i2c_get_clientdata(client);
+        struct m62332_data *data = iio_priv(indio_dev);
+        int ret;
+
+        ret = m62332_set_value(indio_dev, data->save[0], 0);
+        if (ret < 0)
+                return ret;
+
+        return m62332_set_value(indio_dev, data->save[1], 1);
+}
+
+static SIMPLE_DEV_PM_OPS(m62332_pm_ops, m62332_suspend, m62332_resume);
+#define M62332_PM_OPS (&m62332_pm_ops)
+#else
+#define M62332_PM_OPS NULL
+#endif
+
+static const struct iio_info m62332_info = {
+        .read_raw = m62332_read_raw,
+        .write_raw = m62332_write_raw,
+        .driver_module = THIS_MODULE,
+};
+
+#define M62332_CHANNEL(chan) {                          \
+        .type = IIO_VOLTAGE,                            \
+        .indexed = 1,                                   \
+        .output = 1,                                    \
+        .channel = (chan),                              \
+        .datasheet_name = "CH" #chan,                   \
+        .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |  \
+                BIT(IIO_CHAN_INFO_SCALE) |              \
+                BIT(IIO_CHAN_INFO_OFFSET),              \
+}
+
+static const struct iio_chan_spec m62332_channels[M62332_CHANNELS] = {
+        M62332_CHANNEL(0),
+        M62332_CHANNEL(1)
+};
+
+static int m62332_probe(struct i2c_client *client,
+                        const struct i2c_device_id *id)
+{
+        struct m62332_data *data;
+        struct iio_dev *indio_dev;
+        int ret;
+
+        indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
+        if (!indio_dev)
+                return -ENOMEM;
+        data = iio_priv(indio_dev);
+        i2c_set_clientdata(client, indio_dev);
+        data->client = client;
+
+        mutex_init(&data->mutex);
+
+        data->vcc = devm_regulator_get(&client->dev, "VCC");
+        if (IS_ERR(data->vcc))
+                return PTR_ERR(data->vcc);
+
+        /* establish that the iio_dev is a child of the i2c device */
+        indio_dev->dev.parent = &client->dev;
+
+        indio_dev->num_channels = M62332_CHANNELS;
+        indio_dev->channels = m62332_channels;
+        indio_dev->modes = INDIO_DIRECT_MODE;
+        indio_dev->info = &m62332_info;
+
+        ret = regulator_get_voltage(data->vcc);
+        if (ret < 0)
+                return ret;
+        data->vref_mv = ret / 1000; /* mV */
+
+        ret = iio_map_array_register(indio_dev, client->dev.platform_data);
+        if (ret < 0)
+                return ret;
+
+        ret = iio_device_register(indio_dev);
+        if (ret < 0)
+                goto err;
+
+        return 0;
+
+err:
+        iio_map_array_unregister(indio_dev);
+        return ret;
+}
+
+static int m62332_remove(struct i2c_client *client)
+{
+        struct iio_dev *indio_dev = i2c_get_clientdata(client);
+
+        iio_device_unregister(indio_dev);
+        iio_map_array_unregister(indio_dev);
+
+        return 0;
+}
+
+static const struct i2c_device_id m62332_id[] = {
+        { "m62332", },
+        { }
+};
+MODULE_DEVICE_TABLE(i2c, m62332_id);
+
+static struct i2c_driver m62332_driver = {
+        .driver = {
+                .name   = "m62332",
+                .pm     = M62332_PM_OPS,
+        },
+        .probe          = m62332_probe,
+        .remove         = m62332_remove,
+        .id_table       = m62332_id,
+};
+module_i2c_driver(m62332_driver);
+
+MODULE_AUTHOR("Dmitry Eremin-Solenikov");
+MODULE_DESCRIPTION("M62332 8-bit DAC");
+MODULE_LICENSE("GPL v2");