leds-lp5521.c

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/*
 * LP5521 LED chip driver.
 *
 * Copyright (C) 2010 Nokia Corporation
 *
 * Contact: Samu Onkalo <[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, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
 * 02110-1301 USA
 */

#include <linux/module.h>
#include <linux/init.h>
#include <linux/i2c.h>
#include <linux/mutex.h>
#include <linux/gpio.h>
#include <linux/interrupt.h>
#include <linux/delay.h>
#include <linux/ctype.h>
#include <linux/spinlock.h>
#include <linux/wait.h>
#include <linux/leds.h>
#include <linux/leds-lp5521.h>
#include <linux/workqueue.h>
#include <linux/slab.h>

#define LP5521_PROGRAM_LENGTH       32  /* in bytes */

#define LP5521_MAX_LEDS         3   /* Maximum number of LEDs */
#define LP5521_MAX_ENGINES      3   /* Maximum number of engines */

#define LP5521_ENG_MASK_BASE        0x30    /* 00110000 */
#define LP5521_ENG_STATUS_MASK      0x07    /* 00000111 */

#define LP5521_CMD_LOAD         0x15    /* 00010101 */
#define LP5521_CMD_RUN          0x2a    /* 00101010 */
#define LP5521_CMD_DIRECT       0x3f    /* 00111111 */
#define LP5521_CMD_DISABLED     0x00    /* 00000000 */

/* Registers */
#define LP5521_REG_ENABLE       0x00
#define LP5521_REG_OP_MODE      0x01
#define LP5521_REG_R_PWM        0x02
#define LP5521_REG_G_PWM        0x03
#define LP5521_REG_B_PWM        0x04
#define LP5521_REG_R_CURRENT        0x05
#define LP5521_REG_G_CURRENT        0x06
#define LP5521_REG_B_CURRENT        0x07
#define LP5521_REG_CONFIG       0x08
#define LP5521_REG_R_CHANNEL_PC     0x09
#define LP5521_REG_G_CHANNEL_PC     0x0A
#define LP5521_REG_B_CHANNEL_PC     0x0B
#define LP5521_REG_STATUS       0x0C
#define LP5521_REG_RESET        0x0D
#define LP5521_REG_GPO          0x0E
#define LP5521_REG_R_PROG_MEM       0x10
#define LP5521_REG_G_PROG_MEM       0x30
#define LP5521_REG_B_PROG_MEM       0x50

#define LP5521_PROG_MEM_BASE        LP5521_REG_R_PROG_MEM
#define LP5521_PROG_MEM_SIZE        0x20

/* Base register to set LED current */
#define LP5521_REG_LED_CURRENT_BASE LP5521_REG_R_CURRENT

/* Base register to set the brightness */
#define LP5521_REG_LED_PWM_BASE     LP5521_REG_R_PWM

/* Bits in ENABLE register */
#define LP5521_MASTER_ENABLE        0x40    /* Chip master enable */
#define LP5521_LOGARITHMIC_PWM      0x80    /* Logarithmic PWM adjustment */
#define LP5521_EXEC_RUN         0x2A
#define LP5521_ENABLE_DEFAULT   \
    (LP5521_MASTER_ENABLE | LP5521_LOGARITHMIC_PWM)
#define LP5521_ENABLE_RUN_PROGRAM   \
    (LP5521_ENABLE_DEFAULT | LP5521_EXEC_RUN)

/* Status */
#define LP5521_EXT_CLK_USED     0x08

/* default R channel current register value */
#define LP5521_REG_R_CURR_DEFAULT   0xAF

/* Pattern Mode */
#define PATTERN_OFF 0

struct lp5521_engine {
    int     id;
    u8      mode;
    u8      prog_page;
    u8      engine_mask;
};

struct lp5521_led {
    int         id;
    u8          chan_nr;
    u8          led_current;
    u8          max_current;
    struct led_classdev cdev;
    struct work_struct  brightness_work;
    u8          brightness;
};

struct lp5521_chip {
    struct lp5521_platform_data *pdata;
    struct mutex        lock; /* Serialize control */
    struct i2c_client   *client;
    struct lp5521_engine    engines[LP5521_MAX_ENGINES];
    struct lp5521_led   leds[LP5521_MAX_LEDS];
    u8          num_channels;
    u8          num_leds;
};

static inline struct lp5521_led *cdev_to_led(struct led_classdev *cdev)
{
    return container_of(cdev, struct lp5521_led, cdev);
}

static inline struct lp5521_chip *engine_to_lp5521(struct lp5521_engine *engine)
{
    return container_of(engine, struct lp5521_chip,
                engines[engine->id - 1]);
}

static inline struct lp5521_chip *led_to_lp5521(struct lp5521_led *led)
{
    return container_of(led, struct lp5521_chip,
                leds[led->id]);
}

static void lp5521_led_brightness_work(struct work_struct *work);

static inline int lp5521_write(struct i2c_client *client, u8 reg, u8 value)
{
    return i2c_smbus_write_byte_data(client, reg, value);
}

static int lp5521_read(struct i2c_client *client, u8 reg, u8 *buf)
{
    s32 ret;

    ret = i2c_smbus_read_byte_data(client, reg);
    if (ret < 0)
        return -EIO;

    *buf = ret;
    return 0;
}

static int lp5521_set_engine_mode(struct lp5521_engine *engine, u8 mode)
{
    struct lp5521_chip *chip = engine_to_lp5521(engine);
    struct i2c_client *client = chip->client;
    int ret;
    u8 engine_state;

    /* Only transition between RUN and DIRECT mode are handled here */
    if (mode == LP5521_CMD_LOAD)
        return 0;

    if (mode == LP5521_CMD_DISABLED)
        mode = LP5521_CMD_DIRECT;

    ret = lp5521_read(client, LP5521_REG_OP_MODE, &engine_state);
    if (ret < 0)
        return ret;

    /* set mode only for this engine */
    engine_state &= ~(engine->engine_mask);
    mode &= engine->engine_mask;
    engine_state |= mode;
    return lp5521_write(client, LP5521_REG_OP_MODE, engine_state);
}

static int lp5521_load_program(struct lp5521_engine *eng, const u8 *pattern)
{
    struct lp5521_chip *chip = engine_to_lp5521(eng);
    struct i2c_client *client = chip->client;
    int ret;
    int addr;
    u8 mode;

    /* move current engine to direct mode and remember the state */
    ret = lp5521_set_engine_mode(eng, LP5521_CMD_DIRECT);
    if (ret)
        return ret;

    /* Mode change requires min 500 us delay. 1 - 2 ms  with margin */
    usleep_range(1000, 2000);
    ret = lp5521_read(client, LP5521_REG_OP_MODE, &mode);
    if (ret)
        return ret;

    /* For loading, all the engines to load mode */
    lp5521_write(client, LP5521_REG_OP_MODE, LP5521_CMD_DIRECT);
    /* Mode change requires min 500 us delay. 1 - 2 ms  with margin */
    usleep_range(1000, 2000);
    lp5521_write(client, LP5521_REG_OP_MODE, LP5521_CMD_LOAD);
    /* Mode change requires min 500 us delay. 1 - 2 ms  with margin */
    usleep_range(1000, 2000);

    addr = LP5521_PROG_MEM_BASE + eng->prog_page * LP5521_PROG_MEM_SIZE;
    i2c_smbus_write_i2c_block_data(client,
                addr,
                LP5521_PROG_MEM_SIZE,
                pattern);

    return lp5521_write(client, LP5521_REG_OP_MODE, mode);
}

static int lp5521_set_led_current(struct lp5521_chip *chip, int led, u8 curr)
{
    return lp5521_write(chip->client,
            LP5521_REG_LED_CURRENT_BASE + chip->leds[led].chan_nr,
            curr);
}

static void lp5521_init_engine(struct lp5521_chip *chip)
{
    int i;
    for (i = 0; i < ARRAY_SIZE(chip->engines); i++) {
        chip->engines[i].id = i + 1;
        chip->engines[i].engine_mask = LP5521_ENG_MASK_BASE >> (i * 2);
        chip->engines[i].prog_page = i;
    }
}

static int lp5521_configure(struct i2c_client *client)
{
    struct lp5521_chip *chip = i2c_get_clientdata(client);
    int ret;
    u8 cfg;

    lp5521_init_engine(chip);

    /* Set all PWMs to direct control mode */
    ret = lp5521_write(client, LP5521_REG_OP_MODE, LP5521_CMD_DIRECT);

    cfg = chip->pdata->update_config ?
        : (LP5521_PWRSAVE_EN | LP5521_CP_MODE_AUTO | LP5521_R_TO_BATT);
    ret |= lp5521_write(client, LP5521_REG_CONFIG, cfg);

    /* Initialize all channels PWM to zero -> leds off */
    ret |= lp5521_write(client, LP5521_REG_R_PWM, 0);
    ret |= lp5521_write(client, LP5521_REG_G_PWM, 0);
    ret |= lp5521_write(client, LP5521_REG_B_PWM, 0);

    /* Set engines are set to run state when OP_MODE enables engines */
    ret |= lp5521_write(client, LP5521_REG_ENABLE,
            LP5521_ENABLE_RUN_PROGRAM);
    /* enable takes 500us. 1 - 2 ms leaves some margin */
    usleep_range(1000, 2000);

    return ret;
}

static int lp5521_run_selftest(struct lp5521_chip *chip, char *buf)
{
    int ret;
    u8 status;

    ret = lp5521_read(chip->client, LP5521_REG_STATUS, &status);
    if (ret < 0)
        return ret;

    /* Check that ext clock is really in use if requested */
    if (chip->pdata && chip->pdata->clock_mode == LP5521_CLOCK_EXT)
        if  ((status & LP5521_EXT_CLK_USED) == 0)
            return -EIO;
    return 0;
}

static void lp5521_set_brightness(struct led_classdev *cdev,
                 enum led_brightness brightness)
{
    struct lp5521_led *led = cdev_to_led(cdev);
    led->brightness = (u8)brightness;
    schedule_work(&led->brightness_work);
}

static void lp5521_led_brightness_work(struct work_struct *work)
{
    struct lp5521_led *led = container_of(work,
                          struct lp5521_led,
                          brightness_work);
    struct lp5521_chip *chip = led_to_lp5521(led);
    struct i2c_client *client = chip->client;

    mutex_lock(&chip->lock);
    lp5521_write(client, LP5521_REG_LED_PWM_BASE + led->chan_nr,
        led->brightness);
    mutex_unlock(&chip->lock);
}

/* Detect the chip by setting its ENABLE register and reading it back. */
static int lp5521_detect(struct i2c_client *client)
{
    int ret;
    u8 buf;

    ret = lp5521_write(client, LP5521_REG_ENABLE, LP5521_ENABLE_DEFAULT);
    if (ret)
        return ret;
    /* enable takes 500us. 1 - 2 ms leaves some margin */
    usleep_range(1000, 2000);
    ret = lp5521_read(client, LP5521_REG_ENABLE, &buf);
    if (ret)
        return ret;
    if (buf != LP5521_ENABLE_DEFAULT)
        return -ENODEV;

    return 0;
}

/* Set engine mode and create appropriate sysfs attributes, if required. */
static int lp5521_set_mode(struct lp5521_engine *engine, u8 mode)
{
    int ret = 0;

    /* if in that mode already do nothing, except for run */
    if (mode == engine->mode && mode != LP5521_CMD_RUN)
        return 0;

    if (mode == LP5521_CMD_RUN) {
        ret = lp5521_set_engine_mode(engine, LP5521_CMD_RUN);
    } else if (mode == LP5521_CMD_LOAD) {
        lp5521_set_engine_mode(engine, LP5521_CMD_DISABLED);
        lp5521_set_engine_mode(engine, LP5521_CMD_LOAD);
    } else if (mode == LP5521_CMD_DISABLED) {
        lp5521_set_engine_mode(engine, LP5521_CMD_DISABLED);
    }

    engine->mode = mode;

    return ret;
}

static int lp5521_do_store_load(struct lp5521_engine *engine,
                const char *buf, size_t len)
{
    struct lp5521_chip *chip = engine_to_lp5521(engine);
    struct i2c_client *client = chip->client;
    int  ret, nrchars, offset = 0, i = 0;
    char c[3];
    unsigned cmd;
    u8 pattern[LP5521_PROGRAM_LENGTH] = {0};

    while ((offset < len - 1) && (i < LP5521_PROGRAM_LENGTH)) {
        /* separate sscanfs because length is working only for %s */
        ret = sscanf(buf + offset, "%2s%n ", c, &nrchars);
        if (ret != 2)
            goto fail;
        ret = sscanf(c, "%2x", &cmd);
        if (ret != 1)
            goto fail;
        pattern[i] = (u8)cmd;

        offset += nrchars;
        i++;
    }

    /* Each instruction is 16bit long. Check that length is even */
    if (i % 2)
        goto fail;

    mutex_lock(&chip->lock);
    if (engine->mode == LP5521_CMD_LOAD)
        ret = lp5521_load_program(engine, pattern);
    else
        ret = -EINVAL;
    mutex_unlock(&chip->lock);

    if (ret) {
        dev_err(&client->dev, "failed loading pattern\n");
        return ret;
    }

    return len;
fail:
    dev_err(&client->dev, "wrong pattern format\n");
    return -EINVAL;
}

static ssize_t store_engine_load(struct device *dev,
                     struct device_attribute *attr,
                     const char *buf, size_t len, int nr)
{
    struct i2c_client *client = to_i2c_client(dev);
    struct lp5521_chip *chip = i2c_get_clientdata(client);
    return lp5521_do_store_load(&chip->engines[nr - 1], buf, len);
}

#define store_load(nr)                          \
static ssize_t store_engine##nr##_load(struct device *dev,      \
                     struct device_attribute *attr, \
                     const char *buf, size_t len)   \
{                                   \
    return store_engine_load(dev, attr, buf, len, nr);      \
}
store_load(1)
store_load(2)
store_load(3)

static ssize_t show_engine_mode(struct device *dev,
                struct device_attribute *attr,
                char *buf, int nr)
{
    struct i2c_client *client = to_i2c_client(dev);
    struct lp5521_chip *chip = i2c_get_clientdata(client);
    switch (chip->engines[nr - 1].mode) {
    case LP5521_CMD_RUN:
        return sprintf(buf, "run\n");
    case LP5521_CMD_LOAD:
        return sprintf(buf, "load\n");
    case LP5521_CMD_DISABLED:
        return sprintf(buf, "disabled\n");
    default:
        return sprintf(buf, "disabled\n");
    }
}

#define show_mode(nr)                           \
static ssize_t show_engine##nr##_mode(struct device *dev,       \
                    struct device_attribute *attr,  \
                    char *buf)              \
{                                   \
    return show_engine_mode(dev, attr, buf, nr);            \
}
show_mode(1)
show_mode(2)
show_mode(3)

static ssize_t store_engine_mode(struct device *dev,
                 struct device_attribute *attr,
                 const char *buf, size_t len, int nr)
{
    struct i2c_client *client = to_i2c_client(dev);
    struct lp5521_chip *chip = i2c_get_clientdata(client);
    struct lp5521_engine *engine = &chip->engines[nr - 1];
    mutex_lock(&chip->lock);

    if (!strncmp(buf, "run", 3))
        lp5521_set_mode(engine, LP5521_CMD_RUN);
    else if (!strncmp(buf, "load", 4))
        lp5521_set_mode(engine, LP5521_CMD_LOAD);
    else if (!strncmp(buf, "disabled", 8))
        lp5521_set_mode(engine, LP5521_CMD_DISABLED);

    mutex_unlock(&chip->lock);
    return len;
}

#define store_mode(nr)                          \
static ssize_t store_engine##nr##_mode(struct device *dev,      \
                     struct device_attribute *attr, \
                     const char *buf, size_t len)   \
{                                   \
    return store_engine_mode(dev, attr, buf, len, nr);      \
}
store_mode(1)
store_mode(2)
store_mode(3)

static ssize_t show_max_current(struct device *dev,
                struct device_attribute *attr,
                char *buf)
{
    struct led_classdev *led_cdev = dev_get_drvdata(dev);
    struct lp5521_led *led = cdev_to_led(led_cdev);

    return sprintf(buf, "%d\n", led->max_current);
}

static ssize_t show_current(struct device *dev,
                struct device_attribute *attr,
                char *buf)
{
    struct led_classdev *led_cdev = dev_get_drvdata(dev);
    struct lp5521_led *led = cdev_to_led(led_cdev);

    return sprintf(buf, "%d\n", led->led_current);
}

static ssize_t store_current(struct device *dev,
                 struct device_attribute *attr,
                 const char *buf, size_t len)
{
    struct led_classdev *led_cdev = dev_get_drvdata(dev);
    struct lp5521_led *led = cdev_to_led(led_cdev);
    struct lp5521_chip *chip = led_to_lp5521(led);
    ssize_t ret;
    unsigned long curr;

    if (kstrtoul(buf, 0, &curr))
        return -EINVAL;

    if (curr > led->max_current)
        return -EINVAL;

    mutex_lock(&chip->lock);
    ret = lp5521_set_led_current(chip, led->id, curr);
    mutex_unlock(&chip->lock);

    if (ret < 0)
        return ret;

    led->led_current = (u8)curr;

    return len;
}

static ssize_t lp5521_selftest(struct device *dev,
                   struct device_attribute *attr,
                   char *buf)
{
    struct i2c_client *client = to_i2c_client(dev);
    struct lp5521_chip *chip = i2c_get_clientdata(client);
    int ret;

    mutex_lock(&chip->lock);
    ret = lp5521_run_selftest(chip, buf);
    mutex_unlock(&chip->lock);
    return sprintf(buf, "%s\n", ret ? "FAIL" : "OK");
}

static void lp5521_clear_program_memory(struct i2c_client *cl)
{
    int i;
    u8 rgb_mem[] = {
        LP5521_REG_R_PROG_MEM,
        LP5521_REG_G_PROG_MEM,
        LP5521_REG_B_PROG_MEM,
    };

    for (i = 0; i < ARRAY_SIZE(rgb_mem); i++) {
        lp5521_write(cl, rgb_mem[i], 0);
        lp5521_write(cl, rgb_mem[i] + 1, 0);
    }
}

static void lp5521_write_program_memory(struct i2c_client *cl,
                u8 base, u8 *rgb, int size)
{
    int i;

    if (!rgb || size <= 0)
        return;

    for (i = 0; i < size; i++)
        lp5521_write(cl, base + i, *(rgb + i));

    lp5521_write(cl, base + i, 0);
    lp5521_write(cl, base + i + 1, 0);
}

static inline struct lp5521_led_pattern *lp5521_get_pattern
                    (struct lp5521_chip *chip, u8 offset)
{
    struct lp5521_led_pattern *ptn;
    ptn = chip->pdata->patterns + (offset - 1);
    return ptn;
}

static void lp5521_run_led_pattern(int mode, struct lp5521_chip *chip)
{
    struct lp5521_led_pattern *ptn;
    struct i2c_client *cl = chip->client;
    int num_patterns = chip->pdata->num_patterns;

    if (mode > num_patterns || !(chip->pdata->patterns))
        return;

    if (mode == PATTERN_OFF) {
        lp5521_write(cl, LP5521_REG_ENABLE, LP5521_ENABLE_DEFAULT);
        usleep_range(1000, 2000);
        lp5521_write(cl, LP5521_REG_OP_MODE, LP5521_CMD_DIRECT);
    } else {
        ptn = lp5521_get_pattern(chip, mode);
        if (!ptn)
            return;

        lp5521_write(cl, LP5521_REG_OP_MODE, LP5521_CMD_LOAD);
        usleep_range(1000, 2000);

        lp5521_clear_program_memory(cl);

        lp5521_write_program_memory(cl, LP5521_REG_R_PROG_MEM,
                    ptn->r, ptn->size_r);
        lp5521_write_program_memory(cl, LP5521_REG_G_PROG_MEM,
                    ptn->g, ptn->size_g);
        lp5521_write_program_memory(cl, LP5521_REG_B_PROG_MEM,
                    ptn->b, ptn->size_b);

        lp5521_write(cl, LP5521_REG_OP_MODE, LP5521_CMD_RUN);
        usleep_range(1000, 2000);
        lp5521_write(cl, LP5521_REG_ENABLE, LP5521_ENABLE_RUN_PROGRAM);
    }
}

static ssize_t store_led_pattern(struct device *dev,
                struct device_attribute *attr,
                const char *buf, size_t len)
{
    struct lp5521_chip *chip = i2c_get_clientdata(to_i2c_client(dev));
    unsigned long val;
    int ret;

    ret = strict_strtoul(buf, 16, &val);
    if (ret)
        return ret;

    lp5521_run_led_pattern(val, chip);

    return len;
}

/* led class device attributes */
static DEVICE_ATTR(led_current, S_IRUGO | S_IWUSR, show_current, store_current);
static DEVICE_ATTR(max_current, S_IRUGO , show_max_current, NULL);

static struct attribute *lp5521_led_attributes[] = {
    &dev_attr_led_current.attr,
    &dev_attr_max_current.attr,
    NULL,
};

static struct attribute_group lp5521_led_attribute_group = {
    .attrs = lp5521_led_attributes
};

/* device attributes */
static DEVICE_ATTR(engine1_mode, S_IRUGO | S_IWUSR,
           show_engine1_mode, store_engine1_mode);
static DEVICE_ATTR(engine2_mode, S_IRUGO | S_IWUSR,
           show_engine2_mode, store_engine2_mode);
static DEVICE_ATTR(engine3_mode, S_IRUGO | S_IWUSR,
           show_engine3_mode, store_engine3_mode);
static DEVICE_ATTR(engine1_load, S_IWUSR, NULL, store_engine1_load);
static DEVICE_ATTR(engine2_load, S_IWUSR, NULL, store_engine2_load);
static DEVICE_ATTR(engine3_load, S_IWUSR, NULL, store_engine3_load);
static DEVICE_ATTR(selftest, S_IRUGO, lp5521_selftest, NULL);
static DEVICE_ATTR(led_pattern, S_IWUSR, NULL, store_led_pattern);

static struct attribute *lp5521_attributes[] = {
    &dev_attr_engine1_mode.attr,
    &dev_attr_engine2_mode.attr,
    &dev_attr_engine3_mode.attr,
    &dev_attr_selftest.attr,
    &dev_attr_engine1_load.attr,
    &dev_attr_engine2_load.attr,
    &dev_attr_engine3_load.attr,
    &dev_attr_led_pattern.attr,
    NULL
};

static const struct attribute_group lp5521_group = {
    .attrs = lp5521_attributes,
};

static int lp5521_register_sysfs(struct i2c_client *client)
{
    struct device *dev = &client->dev;
    return sysfs_create_group(&dev->kobj, &lp5521_group);
}

static void lp5521_unregister_sysfs(struct i2c_client *client)
{
    struct lp5521_chip *chip = i2c_get_clientdata(client);
    struct device *dev = &client->dev;
    int i;

    sysfs_remove_group(&dev->kobj, &lp5521_group);

    for (i = 0; i < chip->num_leds; i++)
        sysfs_remove_group(&chip->leds[i].cdev.dev->kobj,
                &lp5521_led_attribute_group);
}

static int __devinit lp5521_init_led(struct lp5521_led *led,
                struct i2c_client *client,
                int chan, struct lp5521_platform_data *pdata)
{
    struct device *dev = &client->dev;
    char name[32];
    int res;

    if (chan >= LP5521_MAX_LEDS)
        return -EINVAL;

    if (pdata->led_config[chan].led_current == 0)
        return 0;

    led->led_current = pdata->led_config[chan].led_current;
    led->max_current = pdata->led_config[chan].max_current;
    led->chan_nr = pdata->led_config[chan].chan_nr;

    if (led->chan_nr >= LP5521_MAX_LEDS) {
        dev_err(dev, "Use channel numbers between 0 and %d\n",
            LP5521_MAX_LEDS - 1);
        return -EINVAL;
    }

    led->cdev.brightness_set = lp5521_set_brightness;
    if (pdata->led_config[chan].name) {
        led->cdev.name = pdata->led_config[chan].name;
    } else {
        snprintf(name, sizeof(name), "%s:channel%d",
            pdata->label ?: client->name, chan);
        led->cdev.name = name;
    }

    res = led_classdev_register(dev, &led->cdev);
    if (res < 0) {
        dev_err(dev, "couldn't register led on channel %d\n", chan);
        return res;
    }

    res = sysfs_create_group(&led->cdev.dev->kobj,
            &lp5521_led_attribute_group);
    if (res < 0) {
        dev_err(dev, "couldn't register current attribute\n");
        led_classdev_unregister(&led->cdev);
        return res;
    }
    return 0;
}

static int __devinit lp5521_probe(struct i2c_client *client,
            const struct i2c_device_id *id)
{
    struct lp5521_chip      *chip;
    struct lp5521_platform_data *pdata;
    int ret, i, led;
    u8 buf;

    chip = devm_kzalloc(&client->dev, sizeof(*chip), GFP_KERNEL);
    if (!chip)
        return -ENOMEM;

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

    pdata = client->dev.platform_data;

    if (!pdata) {
        dev_err(&client->dev, "no platform data\n");
        return -EINVAL;
    }

    mutex_init(&chip->lock);

    chip->pdata   = pdata;

    if (pdata->setup_resources) {
        ret = pdata->setup_resources();
        if (ret < 0)
            return ret;
    }

    if (pdata->enable) {
        pdata->enable(0);
        usleep_range(1000, 2000); /* Keep enable down at least 1ms */
        pdata->enable(1);
        usleep_range(1000, 2000); /* 500us abs min. */
    }

    lp5521_write(client, LP5521_REG_RESET, 0xff);
    usleep_range(10000, 20000); /*
                     * Exact value is not available. 10 - 20ms
                     * appears to be enough for reset.
                     */

    /*
     * Make sure that the chip is reset by reading back the r channel
     * current reg. This is dummy read is required on some platforms -
     * otherwise further access to the R G B channels in the
     * LP5521_REG_ENABLE register will not have any effect - strange!
     */
    ret = lp5521_read(client, LP5521_REG_R_CURRENT, &buf);
    if (ret || buf != LP5521_REG_R_CURR_DEFAULT) {
        dev_err(&client->dev, "error in resetting chip\n");
        goto fail2;
    }
    usleep_range(10000, 20000);

    ret = lp5521_detect(client);

    if (ret) {
        dev_err(&client->dev, "Chip not found\n");
        goto fail2;
    }

    dev_info(&client->dev, "%s programmable led chip found\n", id->name);

    ret = lp5521_configure(client);
    if (ret < 0) {
        dev_err(&client->dev, "error configuring chip\n");
        goto fail1;
    }

    /* Initialize leds */
    chip->num_channels = pdata->num_channels;
    chip->num_leds = 0;
    led = 0;
    for (i = 0; i < pdata->num_channels; i++) {
        /* Do not initialize channels that are not connected */
        if (pdata->led_config[i].led_current == 0)
            continue;

        ret = lp5521_init_led(&chip->leds[led], client, i, pdata);
        if (ret) {
            dev_err(&client->dev, "error initializing leds\n");
            goto fail2;
        }
        chip->num_leds++;

        chip->leds[led].id = led;
        /* Set initial LED current */
        lp5521_set_led_current(chip, led,
                chip->leds[led].led_current);

        INIT_WORK(&(chip->leds[led].brightness_work),
            lp5521_led_brightness_work);

        led++;
    }

    ret = lp5521_register_sysfs(client);
    if (ret) {
        dev_err(&client->dev, "registering sysfs failed\n");
        goto fail2;
    }
    return ret;
fail2:
    for (i = 0; i < chip->num_leds; i++) {
        led_classdev_unregister(&chip->leds[i].cdev);
        cancel_work_sync(&chip->leds[i].brightness_work);
    }
fail1:
    if (pdata->enable)
        pdata->enable(0);
    if (pdata->release_resources)
        pdata->release_resources();
    return ret;
}

static int __devexit lp5521_remove(struct i2c_client *client)
{
    struct lp5521_chip *chip = i2c_get_clientdata(client);
    int i;

    lp5521_run_led_pattern(PATTERN_OFF, chip);
    lp5521_unregister_sysfs(client);

    for (i = 0; i < chip->num_leds; i++) {
        led_classdev_unregister(&chip->leds[i].cdev);
        cancel_work_sync(&chip->leds[i].brightness_work);
    }

    if (chip->pdata->enable)
        chip->pdata->enable(0);
    if (chip->pdata->release_resources)
        chip->pdata->release_resources();
    return 0;
}

static const struct i2c_device_id lp5521_id[] = {
    { "lp5521", 0 }, /* Three channel chip */
    { }
};
MODULE_DEVICE_TABLE(i2c, lp5521_id);

static struct i2c_driver lp5521_driver = {
    .driver = {
        .name   = "lp5521",
    },
    .probe      = lp5521_probe,
    .remove     = __devexit_p(lp5521_remove),
    .id_table   = lp5521_id,
};

module_i2c_driver(lp5521_driver);

MODULE_AUTHOR("Mathias Nyman, Yuri Zaporozhets, Samu Onkalo");
MODULE_DESCRIPTION("LP5521 LED engine");
MODULE_LICENSE("GPL v2");