/*
 *  max517.c - Support for Maxim MAX517, MAX518 and MAX519
 *
 *  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.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

#include <linux/module.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/jiffies.h>
#include <linux/i2c.h>
#include <linux/err.h>

#include <linux/iio/iio.h>
#include <linux/iio/sysfs.h>
#include <linux/iio/dac/max517.h>

#define MAX517_DRV_NAME "max517"

/* Commands */
#define COMMAND_CHANNEL0        0x00
#define COMMAND_CHANNEL1        0x01 /* for MAX518 and MAX519 */
#define COMMAND_PD              0x08 /* Power Down */

enum max517_device_ids {
        ID_MAX517,
        ID_MAX518,
        ID_MAX519,
};

struct max517_data {
        struct i2c_client       *client;
        unsigned short          vref_mv[2];
};

/*
 * channel: bit 0: channel 1
 *          bit 1: channel 2
 * (this way, it's possible to set both channels at once)
 */
static int max517_set_value(struct iio_dev *indio_dev,
        long val, int channel)
{
        struct max517_data *data = iio_priv(indio_dev);
        struct i2c_client *client = data->client;
        u8 outbuf[2];
        int res;

        if (val < 0 || val > 255)
                return -EINVAL;

        outbuf[0] = channel;
        outbuf[1] = val;

        res = i2c_master_send(client, outbuf, 2);
        if (res < 0)
                return res;
        else if (res != 2)
                return -EIO;
        else
                return 0;
}

static int max517_read_raw(struct iio_dev *indio_dev,
                           struct iio_chan_spec const *chan,
                           int *val,
                           int *val2,
                           long m)
{
        struct max517_data *data = iio_priv(indio_dev);

        switch (m) {
        case IIO_CHAN_INFO_SCALE:
                /* Corresponds to Vref / 2^(bits) */
                *val = data->vref_mv[chan->channel];
                *val2 = 8;
                return IIO_VAL_FRACTIONAL_LOG2;
        default:
                break;
        }
        return -EINVAL;
}

static int max517_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:
                ret = max517_set_value(indio_dev, val, chan->channel);
                break;
        default:
                ret = -EINVAL;
                break;
        }

        return ret;
}

#ifdef CONFIG_PM_SLEEP
static int max517_suspend(struct device *dev)
{
        u8 outbuf = COMMAND_PD;

        return i2c_master_send(to_i2c_client(dev), &outbuf, 1);
}

static int max517_resume(struct device *dev)
{
        u8 outbuf = 0;

        return i2c_master_send(to_i2c_client(dev), &outbuf, 1);
}

static SIMPLE_DEV_PM_OPS(max517_pm_ops, max517_suspend, max517_resume);
#define MAX517_PM_OPS (&max517_pm_ops)
#else
#define MAX517_PM_OPS NULL
#endif

static const struct iio_info max517_info = {
        .read_raw = max517_read_raw,
        .write_raw = max517_write_raw,
        .driver_module = THIS_MODULE,
};

#define MAX517_CHANNEL(chan) {                          \
        .type = IIO_VOLTAGE,                            \
        .indexed = 1,                                   \
        .output = 1,                                    \
        .channel = (chan),                              \
        .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |  \
        BIT(IIO_CHAN_INFO_SCALE),                       \
        .scan_type = IIO_ST('u', 8, 8, 0),              \
}

static const struct iio_chan_spec max517_channels[] = {
        MAX517_CHANNEL(0),
        MAX517_CHANNEL(1)
};

static int max517_probe(struct i2c_client *client,
                        const struct i2c_device_id *id)
{
        struct max517_data *data;
        struct iio_dev *indio_dev;
        struct max517_platform_data *platform_data = client->dev.platform_data;

        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;

        /* establish that the iio_dev is a child of the i2c device */
        indio_dev->dev.parent = &client->dev;

        /* reduced channel set for MAX517 */
        if (id->driver_data == ID_MAX517)
                indio_dev->num_channels = 1;
        else
                indio_dev->num_channels = 2;
        indio_dev->channels = max517_channels;
        indio_dev->modes = INDIO_DIRECT_MODE;
        indio_dev->info = &max517_info;

        /*
         * Reference voltage on MAX518 and default is 5V, else take vref_mv
         * from platform_data
         */
        if (id->driver_data == ID_MAX518 || !platform_data) {
                data->vref_mv[0] = data->vref_mv[1] = 5000; /* mV */
        } else {
                data->vref_mv[0] = platform_data->vref_mv[0];
                data->vref_mv[1] = platform_data->vref_mv[1];
        }

        return iio_device_register(indio_dev);
}

static int max517_remove(struct i2c_client *client)
{
        iio_device_unregister(i2c_get_clientdata(client));
        return 0;
}

static const struct i2c_device_id max517_id[] = {
        { "max517", ID_MAX517 },
        { "max518", ID_MAX518 },
        { "max519", ID_MAX519 },
        { }
};
MODULE_DEVICE_TABLE(i2c, max517_id);

static struct i2c_driver max517_driver = {
        .driver = {
                .name   = MAX517_DRV_NAME,
                .pm             = MAX517_PM_OPS,
        },
        .probe          = max517_probe,
        .remove         = max517_remove,
        .id_table       = max517_id,
};
module_i2c_driver(max517_driver);

MODULE_AUTHOR("Roland Stigge <stigge@antcom.de>");
MODULE_DESCRIPTION("MAX517/MAX518/MAX519 8-bit DAC");
MODULE_LICENSE("GPL");