bh1780gli.c

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/*
 * bh1780gli.c
 * ROHM Ambient Light Sensor Driver
 *
 * Copyright (C) 2010 Texas Instruments
 * Author: Hemanth V <[email protected]>
 *
 * 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>
#include <linux/module.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 device *dev)
{
    struct bh1780_data *ddata;
    int state, ret;
    struct i2c_client *client = to_i2c_client(dev);

    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 device *dev)
{
    struct bh1780_data *ddata;
    int state, ret;
    struct i2c_client *client = to_i2c_client(dev);

    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;
}
static SIMPLE_DEV_PM_OPS(bh1780_pm, bh1780_suspend, bh1780_resume);
#define BH1780_PMOPS (&bh1780_pm)
#else
#define BH1780_PMOPS NULL
#endif /* CONFIG_PM */

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

static struct i2c_driver bh1780_driver = {
    .probe      = bh1780_probe,
    .remove     = __devexit_p(bh1780_remove),
    .id_table   = bh1780_id,
    .driver = {
        .name = "bh1780",
        .pm = BH1780_PMOPS,
    },
};

module_i2c_driver(bh1780_driver);

MODULE_DESCRIPTION("BH1780GLI Ambient Light Sensor Driver");
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Hemanth V <[email protected]>");