/*
 *  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;
        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, ARRAY_SIZE(outbuf));
        if (res >= 0 && res != ARRAY_SIZE(outbuf))
                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 mask)
{
        struct m62332_data *data = iio_priv(indio_dev);
        int ret;

        switch (mask) {
        case IIO_CHAN_INFO_SCALE:
                /* Corresponds to Vref / 2^(bits) */
                ret = regulator_get_voltage(data->vcc);
                if (ret < 0)
                        return ret;

                *val = ret / 1000; /* 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)
{
        switch (mask) {
        case IIO_CHAN_INFO_RAW:
                if (val < 0 || val > 255)
                        return -EINVAL;

                return m62332_set_value(indio_dev, val, chan->channel);
        default:
                break;
        }

        return -EINVAL;
}

#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),           \
        .info_mask_shared_by_type = 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 = ARRAY_SIZE(m62332_channels);
        indio_dev->channels = m62332_channels;
        indio_dev->modes = INDIO_DIRECT_MODE;
        indio_dev->info = &m62332_info;

        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);
        m62332_set_value(indio_dev, 0, 0);
        m62332_set_value(indio_dev, 0, 1);

        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");