/*
 * bh1780gli.c
 * ROHM Ambient Light Sensor Driver
 *
 * Copyright (C) 2010 Texas Instruments
 * Author: Hemanth V <hemanthv@ti.com>
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 as published by
 * the Free Software Foundation.
 *
 * 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, see <http://www.gnu.org/licenses/>.
 */
#include <linux/i2c.h>
#include <linux/slab.h>
#include <linux/mutex.h>
#include <linux/platform_device.h>
#include <linux/delay.h>

#define BH1780_REG_CONTROL      0x80
#define BH1780_REG_PARTID       0x8A
#define BH1780_REG_MANFID       0x8B
#define BH1780_REG_DLOW 0x8C
#define BH1780_REG_DHIGH        0x8D

#define BH1780_REVMASK          (0xf)
#define BH1780_POWMASK          (0x3)
#define BH1780_POFF             (0x0)
#define BH1780_PON              (0x3)

/* power on settling time in ms */
#define BH1780_PON_DELAY        2

struct bh1780_data {
        struct i2c_client *client;
        int power_state;
        /* lock for sysfs operations */
        struct mutex lock;
};

static int bh1780_write(struct bh1780_data *ddata, u8 reg, u8 val, char *msg)
{
        int ret = i2c_smbus_write_byte_data(ddata->client, reg, val);
        if (ret < 0)
                dev_err(&ddata->client->dev,
                        "i2c_smbus_write_byte_data failed error %d\
                        Register (%s)\n", ret, msg);
        return ret;
}

static int bh1780_read(struct bh1780_data *ddata, u8 reg, char *msg)
{
        int ret = i2c_smbus_read_byte_data(ddata->client, reg);
        if (ret < 0)
                dev_err(&ddata->client->dev,
                        "i2c_smbus_read_byte_data failed error %d\
                         Register (%s)\n", ret, msg);
        return ret;
}

static ssize_t bh1780_show_lux(struct device *dev,
                                struct device_attribute *attr, char *buf)
{
        struct platform_device *pdev = to_platform_device(dev);
        struct bh1780_data *ddata = platform_get_drvdata(pdev);
        int lsb, msb;

        lsb = bh1780_read(ddata, BH1780_REG_DLOW, "DLOW");
        if (lsb < 0)
                return lsb;

        msb = bh1780_read(ddata, BH1780_REG_DHIGH, "DHIGH");
        if (msb < 0)
                return msb;

        return sprintf(buf, "%d\n", (msb << 8) | lsb);
}

static ssize_t bh1780_show_power_state(struct device *dev,
                                        struct device_attribute *attr,
                                        char *buf)
{
        struct platform_device *pdev = to_platform_device(dev);
        struct bh1780_data *ddata = platform_get_drvdata(pdev);
        int state;

        state = bh1780_read(ddata, BH1780_REG_CONTROL, "CONTROL");
        if (state < 0)
                return state;

        return sprintf(buf, "%d\n", state & BH1780_POWMASK);
}

static ssize_t bh1780_store_power_state(struct device *dev,
                                        struct device_attribute *attr,
                                        const char *buf, size_t count)
{
        struct platform_device *pdev = to_platform_device(dev);
        struct bh1780_data *ddata = platform_get_drvdata(pdev);
        unsigned long val;
        int error;

        error = strict_strtoul(buf, 0, &val);
        if (error)
                return error;

        if (val < BH1780_POFF || val > BH1780_PON)
                return -EINVAL;

        mutex_lock(&ddata->lock);

        error = bh1780_write(ddata, BH1780_REG_CONTROL, val, "CONTROL");
        if (error < 0) {
                mutex_unlock(&ddata->lock);
                return error;
        }

        msleep(BH1780_PON_DELAY);
        ddata->power_state = val;
        mutex_unlock(&ddata->lock);

        return count;
}

static DEVICE_ATTR(lux, S_IRUGO, bh1780_show_lux, NULL);

static DEVICE_ATTR(power_state, S_IWUSR | S_IRUGO,
                bh1780_show_power_state, bh1780_store_power_state);

static struct attribute *bh1780_attributes[] = {
        &dev_attr_power_state.attr,
        &dev_attr_lux.attr,
        NULL
};

static const struct attribute_group bh1780_attr_group = {
        .attrs = bh1780_attributes,
};

static int __devinit bh1780_probe(struct i2c_client *client,
                                                const struct i2c_device_id *id)
{
        int ret;
        struct bh1780_data *ddata = NULL;
        struct i2c_adapter *adapter = to_i2c_adapter(client->dev.parent);

        if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE)) {
                ret = -EIO;
                goto err_op_failed;
        }

        ddata = kzalloc(sizeof(struct bh1780_data), GFP_KERNEL);
        if (ddata == NULL) {
                ret = -ENOMEM;
                goto err_op_failed;
        }

        ddata->client = client;
        i2c_set_clientdata(client, ddata);

        ret = bh1780_read(ddata, BH1780_REG_PARTID, "PART ID");
        if (ret < 0)
                goto err_op_failed;

        dev_info(&client->dev, "Ambient Light Sensor, Rev : %d\n",
                        (ret & BH1780_REVMASK));

        mutex_init(&ddata->lock);

        ret = sysfs_create_group(&client->dev.kobj, &bh1780_attr_group);
        if (ret)
                goto err_op_failed;

        return 0;

err_op_failed:
        kfree(ddata);
        return ret;
}

static int __devexit bh1780_remove(struct i2c_client *client)
{
        struct bh1780_data *ddata;

        ddata = i2c_get_clientdata(client);
        sysfs_remove_group(&client->dev.kobj, &bh1780_attr_group);
        kfree(ddata);

        return 0;
}

#ifdef CONFIG_PM
static int bh1780_suspend(struct i2c_client *client, pm_message_t mesg)
{
        struct bh1780_data *ddata;
        int state, ret;

        ddata = i2c_get_clientdata(client);
        state = bh1780_read(ddata, BH1780_REG_CONTROL, "CONTROL");
        if (state < 0)
                return state;

        ddata->power_state = state & BH1780_POWMASK;

        ret = bh1780_write(ddata, BH1780_REG_CONTROL, BH1780_POFF,
                                "CONTROL");

        if (ret < 0)
                return ret;

        return 0;
}

static int bh1780_resume(struct i2c_client *client)
{
        struct bh1780_data *ddata;
        int state, ret;

        ddata = i2c_get_clientdata(client);
        state = ddata->power_state;

        ret = bh1780_write(ddata, BH1780_REG_CONTROL, state,
                                "CONTROL");

        if (ret < 0)
                return ret;

        return 0;
}
#else
#define bh1780_suspend NULL
#define bh1780_resume NULL
#endif /* CONFIG_PM */

static const struct i2c_device_id bh1780_id[] = {
        { "bh1780", 0 },
        { },
};

static struct i2c_driver bh1780_driver = {
        .probe          = bh1780_probe,
        .remove         = bh1780_remove,
        .id_table       = bh1780_id,
        .suspend        = bh1780_suspend,
        .resume         = bh1780_resume,
        .driver = {
                .name = "bh1780"
        },
};

static int __init bh1780_init(void)
{
        return i2c_add_driver(&bh1780_driver);
}

static void __exit bh1780_exit(void)
{
        i2c_del_driver(&bh1780_driver);
}

module_init(bh1780_init)
module_exit(bh1780_exit)

MODULE_DESCRIPTION("BH1780GLI Ambient Light Sensor Driver");
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Hemanth V <hemanthv@ti.com>");