/*
 * apds9802als.c - apds9802  ALS Driver
 *
 * Copyright (C) 2009 Intel Corp
 *
 *  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 *
 * 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; version 2 of the License.
 *
 * 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.,
 * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
 * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 *
 */

#include <linux/module.h>
#include <linux/slab.h>
#include <linux/i2c.h>
#include <linux/err.h>
#include <linux/delay.h>
#include <linux/mutex.h>
#include <linux/sysfs.h>
#include <linux/pm_runtime.h>

#define ALS_MIN_RANGE_VAL 1
#define ALS_MAX_RANGE_VAL 2
#define POWER_STA_ENABLE 1
#define POWER_STA_DISABLE 0

#define DRIVER_NAME "apds9802als"

struct als_data {
        struct mutex mutex;
};

static ssize_t als_sensing_range_show(struct device *dev,
                        struct device_attribute *attr,  char *buf)
{
        struct i2c_client *client = to_i2c_client(dev);
        int  val;

        val = i2c_smbus_read_byte_data(client, 0x81);
        if (val < 0)
                return val;
        if (val & 1)
                return sprintf(buf, "4095\n");
        else
                return sprintf(buf, "65535\n");
}

static int als_wait_for_data_ready(struct device *dev)
{
        struct i2c_client *client = to_i2c_client(dev);
        int ret;
        int retry = 10;

        do {
                msleep(30);
                ret = i2c_smbus_read_byte_data(client, 0x86);
        } while (!(ret & 0x80) && retry--);

        if (retry < 0) {
                dev_warn(dev, "timeout waiting for data ready\n");
                return -ETIMEDOUT;
        }

        return 0;
}

static ssize_t als_lux0_input_data_show(struct device *dev,
                        struct device_attribute *attr, char *buf)
{
        struct i2c_client *client = to_i2c_client(dev);
        struct als_data *data = i2c_get_clientdata(client);
        int ret_val;
        int temp;

        /* Protect against parallel reads */
        pm_runtime_get_sync(dev);
        mutex_lock(&data->mutex);

        /* clear EOC interrupt status */
        i2c_smbus_write_byte(client, 0x40);
        /* start measurement */
        temp = i2c_smbus_read_byte_data(client, 0x81);
        i2c_smbus_write_byte_data(client, 0x81, temp | 0x08);

        ret_val = als_wait_for_data_ready(dev);
        if (ret_val < 0)
                goto failed;

        temp = i2c_smbus_read_byte_data(client, 0x8C); /* LSB data */
        if (temp < 0) {
                ret_val = temp;
                goto failed;
        }
        ret_val = i2c_smbus_read_byte_data(client, 0x8D); /* MSB data */
        if (ret_val < 0)
                goto failed;

        mutex_unlock(&data->mutex);
        pm_runtime_put_sync(dev);

        temp = (ret_val << 8) | temp;
        return sprintf(buf, "%d\n", temp);
failed:
        mutex_unlock(&data->mutex);
        pm_runtime_put_sync(dev);
        return ret_val;
}

static ssize_t als_sensing_range_store(struct device *dev,
                struct device_attribute *attr, const  char *buf, size_t count)
{
        struct i2c_client *client = to_i2c_client(dev);
        struct als_data *data = i2c_get_clientdata(client);
        int ret_val;
        unsigned long val;

        ret_val = kstrtoul(buf, 10, &val);
        if (ret_val)
                return ret_val;

        if (val < 4096)
                val = 1;
        else if (val < 65536)
                val = 2;
        else
                return -ERANGE;

        pm_runtime_get_sync(dev);

        /* Make sure nobody else reads/modifies/writes 0x81 while we
           are active */
        mutex_lock(&data->mutex);

        ret_val = i2c_smbus_read_byte_data(client, 0x81);
        if (ret_val < 0)
                goto fail;

        /* Reset the bits before setting them */
        ret_val = ret_val & 0xFA;

        if (val == 1) /* Setting detection range up to 4k LUX */
                ret_val = (ret_val | 0x01);
        else /* Setting detection range up to 64k LUX*/
                ret_val = (ret_val | 0x00);

        ret_val = i2c_smbus_write_byte_data(client, 0x81, ret_val);

        if (ret_val >= 0) {
                /* All OK */
                mutex_unlock(&data->mutex);
                pm_runtime_put_sync(dev);
                return count;
        }
fail:
        mutex_unlock(&data->mutex);
        pm_runtime_put_sync(dev);
        return ret_val;
}

static int als_set_power_state(struct i2c_client *client, bool on_off)
{
        int ret_val;
        struct als_data *data = i2c_get_clientdata(client);

        mutex_lock(&data->mutex);
        ret_val = i2c_smbus_read_byte_data(client, 0x80);
        if (ret_val < 0)
                goto fail;
        if (on_off)
                ret_val = ret_val | 0x01;
        else
                ret_val = ret_val & 0xFE;
        ret_val = i2c_smbus_write_byte_data(client, 0x80, ret_val);
fail:
        mutex_unlock(&data->mutex);
        return ret_val;
}

static DEVICE_ATTR(lux0_sensor_range, S_IRUGO | S_IWUSR,
        als_sensing_range_show, als_sensing_range_store);
static DEVICE_ATTR(lux0_input, S_IRUGO, als_lux0_input_data_show, NULL);

static struct attribute *mid_att_als[] = {
        &dev_attr_lux0_sensor_range.attr,
        &dev_attr_lux0_input.attr,
        NULL
};

static struct attribute_group m_als_gr = {
        .name = "apds9802als",
        .attrs = mid_att_als
};

static int als_set_default_config(struct i2c_client *client)
{
        int ret_val;
        /* Write the command and then switch on */
        ret_val = i2c_smbus_write_byte_data(client, 0x80, 0x01);
        if (ret_val < 0) {
                dev_err(&client->dev, "failed default switch on write\n");
                return ret_val;
        }
        /* detection range: 1~64K Lux, maunal measurement */
        ret_val = i2c_smbus_write_byte_data(client, 0x81, 0x08);
        if (ret_val < 0)
                dev_err(&client->dev, "failed default LUX on write\n");

        /*  We always get 0 for the 1st measurement after system power on,
         *  so make sure it is finished before user asks for data.
         */
        als_wait_for_data_ready(&client->dev);

        return ret_val;
}

static int apds9802als_probe(struct i2c_client *client,
                             const struct i2c_device_id *id)
{
        int res;
        struct als_data *data;

        data = kzalloc(sizeof(struct als_data), GFP_KERNEL);
        if (data == NULL) {
                dev_err(&client->dev, "Memory allocation failed\n");
                return -ENOMEM;
        }
        i2c_set_clientdata(client, data);
        res = sysfs_create_group(&client->dev.kobj, &m_als_gr);
        if (res) {
                dev_err(&client->dev, "device create file failed\n");
                goto als_error1;
        }
        dev_info(&client->dev, "ALS chip found\n");
        als_set_default_config(client);
        mutex_init(&data->mutex);

        pm_runtime_set_active(&client->dev);
        pm_runtime_enable(&client->dev);

        return res;
als_error1:
        kfree(data);
        return res;
}

static int apds9802als_remove(struct i2c_client *client)
{
        struct als_data *data = i2c_get_clientdata(client);

        pm_runtime_get_sync(&client->dev);

        als_set_power_state(client, false);
        sysfs_remove_group(&client->dev.kobj, &m_als_gr);

        pm_runtime_disable(&client->dev);
        pm_runtime_set_suspended(&client->dev);
        pm_runtime_put_noidle(&client->dev);

        kfree(data);
        return 0;
}

#ifdef CONFIG_PM

static int apds9802als_suspend(struct device *dev)
{
        struct i2c_client *client = to_i2c_client(dev);

        als_set_power_state(client, false);
        return 0;
}

static int apds9802als_resume(struct device *dev)
{
        struct i2c_client *client = to_i2c_client(dev);

        als_set_power_state(client, true);
        return 0;
}

static UNIVERSAL_DEV_PM_OPS(apds9802als_pm_ops, apds9802als_suspend,
        apds9802als_resume, NULL);

#define APDS9802ALS_PM_OPS (&apds9802als_pm_ops)

#else   /* CONFIG_PM */
#define APDS9802ALS_PM_OPS NULL
#endif  /* CONFIG_PM */

static struct i2c_device_id apds9802als_id[] = {
        { DRIVER_NAME, 0 },
        { }
};

MODULE_DEVICE_TABLE(i2c, apds9802als_id);

static struct i2c_driver apds9802als_driver = {
        .driver = {
                .name = DRIVER_NAME,
                .pm = APDS9802ALS_PM_OPS,
        },
        .probe = apds9802als_probe,
        .remove = apds9802als_remove,
        .id_table = apds9802als_id,
};

module_i2c_driver(apds9802als_driver);

MODULE_AUTHOR("Anantha Narayanan <Anantha.Narayanan@intel.com");
MODULE_DESCRIPTION("Avago apds9802als ALS Driver");
MODULE_LICENSE("GPL v2");