leds-lp3944.c

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/*
 * leds-lp3944.c - driver for National Semiconductor LP3944 Funlight Chip
 *
 * Copyright (C) 2009 Antonio Ospite <[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.
 *
 */

/*
 * I2C driver for National Semiconductor LP3944 Funlight Chip
 * http://www.national.com/pf/LP/LP3944.html
 *
 * This helper chip can drive up to 8 leds, with two programmable DIM modes;
 * it could even be used as a gpio expander but this driver assumes it is used
 * as a led controller.
 *
 * The DIM modes are used to set _blink_ patterns for leds, the pattern is
 * specified supplying two parameters:
 *   - period: from 0s to 1.6s
 *   - duty cycle: percentage of the period the led is on, from 0 to 100
 *
 * LP3944 can be found on Motorola A910 smartphone, where it drives the rgb
 * leds, the camera flash light and the displays backlights.
 */

#include <linux/module.h>
#include <linux/i2c.h>
#include <linux/slab.h>
#include <linux/leds.h>
#include <linux/mutex.h>
#include <linux/workqueue.h>
#include <linux/leds-lp3944.h>

/* Read Only Registers */
#define LP3944_REG_INPUT1     0x00 /* LEDs 0-7 InputRegister (Read Only) */
#define LP3944_REG_REGISTER1  0x01 /* None (Read Only) */

#define LP3944_REG_PSC0       0x02 /* Frequency Prescaler 0 (R/W) */
#define LP3944_REG_PWM0       0x03 /* PWM Register 0 (R/W) */
#define LP3944_REG_PSC1       0x04 /* Frequency Prescaler 1 (R/W) */
#define LP3944_REG_PWM1       0x05 /* PWM Register 1 (R/W) */
#define LP3944_REG_LS0        0x06 /* LEDs 0-3 Selector (R/W) */
#define LP3944_REG_LS1        0x07 /* LEDs 4-7 Selector (R/W) */

/* These registers are not used to control leds in LP3944, they can store
 * arbitrary values which the chip will ignore.
 */
#define LP3944_REG_REGISTER8  0x08
#define LP3944_REG_REGISTER9  0x09

#define LP3944_DIM0 0
#define LP3944_DIM1 1

/* period in ms */
#define LP3944_PERIOD_MIN 0
#define LP3944_PERIOD_MAX 1600

/* duty cycle is a percentage */
#define LP3944_DUTY_CYCLE_MIN 0
#define LP3944_DUTY_CYCLE_MAX 100

#define ldev_to_led(c)       container_of(c, struct lp3944_led_data, ldev)

/* Saved data */
struct lp3944_led_data {
    u8 id;
    enum lp3944_type type;
    enum lp3944_status status;
    struct led_classdev ldev;
    struct i2c_client *client;
    struct work_struct work;
};

struct lp3944_data {
    struct mutex lock;
    struct i2c_client *client;
    struct lp3944_led_data leds[LP3944_LEDS_MAX];
};

static int lp3944_reg_read(struct i2c_client *client, u8 reg, u8 *value)
{
    int tmp;

    tmp = i2c_smbus_read_byte_data(client, reg);
    if (tmp < 0)
        return -EINVAL;

    *value = tmp;

    return 0;
}

static int lp3944_reg_write(struct i2c_client *client, u8 reg, u8 value)
{
    return i2c_smbus_write_byte_data(client, reg, value);
}

static int lp3944_dim_set_period(struct i2c_client *client, u8 dim, u16 period)
{
    u8 psc_reg;
    u8 psc_value;
    int err;

    if (dim == LP3944_DIM0)
        psc_reg = LP3944_REG_PSC0;
    else if (dim == LP3944_DIM1)
        psc_reg = LP3944_REG_PSC1;
    else
        return -EINVAL;

    /* Convert period to Prescaler value */
    if (period > LP3944_PERIOD_MAX)
        return -EINVAL;

    psc_value = (period * 255) / LP3944_PERIOD_MAX;

    err = lp3944_reg_write(client, psc_reg, psc_value);

    return err;
}

static int lp3944_dim_set_dutycycle(struct i2c_client *client, u8 dim,
                    u8 duty_cycle)
{
    u8 pwm_reg;
    u8 pwm_value;
    int err;

    if (dim == LP3944_DIM0)
        pwm_reg = LP3944_REG_PWM0;
    else if (dim == LP3944_DIM1)
        pwm_reg = LP3944_REG_PWM1;
    else
        return -EINVAL;

    /* Convert duty cycle to PWM value */
    if (duty_cycle > LP3944_DUTY_CYCLE_MAX)
        return -EINVAL;

    pwm_value = (duty_cycle * 255) / LP3944_DUTY_CYCLE_MAX;

    err = lp3944_reg_write(client, pwm_reg, pwm_value);

    return err;
}

static int lp3944_led_set(struct lp3944_led_data *led, u8 status)
{
    struct lp3944_data *data = i2c_get_clientdata(led->client);
    u8 id = led->id;
    u8 reg;
    u8 val = 0;
    int err;

    dev_dbg(&led->client->dev, "%s: %s, status before normalization:%d\n",
        __func__, led->ldev.name, status);

    switch (id) {
    case LP3944_LED0:
    case LP3944_LED1:
    case LP3944_LED2:
    case LP3944_LED3:
        reg = LP3944_REG_LS0;
        break;
    case LP3944_LED4:
    case LP3944_LED5:
    case LP3944_LED6:
    case LP3944_LED7:
        id -= LP3944_LED4;
        reg = LP3944_REG_LS1;
        break;
    default:
        return -EINVAL;
    }

    if (status > LP3944_LED_STATUS_DIM1)
        return -EINVAL;

    /* invert only 0 and 1, leave unchanged the other values,
     * remember we are abusing status to set blink patterns
     */
    if (led->type == LP3944_LED_TYPE_LED_INVERTED && status < 2)
        status = 1 - status;

    mutex_lock(&data->lock);
    lp3944_reg_read(led->client, reg, &val);

    val &= ~(LP3944_LED_STATUS_MASK << (id << 1));
    val |= (status << (id << 1));

    dev_dbg(&led->client->dev, "%s: %s, reg:%d id:%d status:%d val:%#x\n",
        __func__, led->ldev.name, reg, id, status, val);

    /* set led status */
    err = lp3944_reg_write(led->client, reg, val);
    mutex_unlock(&data->lock);

    return err;
}

static int lp3944_led_set_blink(struct led_classdev *led_cdev,
                unsigned long *delay_on,
                unsigned long *delay_off)
{
    struct lp3944_led_data *led = ldev_to_led(led_cdev);
    u16 period;
    u8 duty_cycle;
    int err;

    /* units are in ms */
    if (*delay_on + *delay_off > LP3944_PERIOD_MAX)
        return -EINVAL;

    if (*delay_on == 0 && *delay_off == 0) {
        /* Special case: the leds subsystem requires a default user
         * friendly blink pattern for the LED.  Let's blink the led
         * slowly (1Hz).
         */
        *delay_on = 500;
        *delay_off = 500;
    }

    period = (*delay_on) + (*delay_off);

    /* duty_cycle is the percentage of period during which the led is ON */
    duty_cycle = 100 * (*delay_on) / period;

    /* invert duty cycle for inverted leds, this has the same effect of
     * swapping delay_on and delay_off
     */
    if (led->type == LP3944_LED_TYPE_LED_INVERTED)
        duty_cycle = 100 - duty_cycle;

    /* NOTE: using always the first DIM mode, this means that all leds
     * will have the same blinking pattern.
     *
     * We could find a way later to have two leds blinking in hardware
     * with different patterns at the same time, falling back to software
     * control for the other ones.
     */
    err = lp3944_dim_set_period(led->client, LP3944_DIM0, period);
    if (err)
        return err;

    err = lp3944_dim_set_dutycycle(led->client, LP3944_DIM0, duty_cycle);
    if (err)
        return err;

    dev_dbg(&led->client->dev, "%s: OK hardware accelerated blink!\n",
        __func__);

    led->status = LP3944_LED_STATUS_DIM0;
    schedule_work(&led->work);

    return 0;
}

static void lp3944_led_set_brightness(struct led_classdev *led_cdev,
                      enum led_brightness brightness)
{
    struct lp3944_led_data *led = ldev_to_led(led_cdev);

    dev_dbg(&led->client->dev, "%s: %s, %d\n",
        __func__, led_cdev->name, brightness);

    led->status = brightness;
    schedule_work(&led->work);
}

static void lp3944_led_work(struct work_struct *work)
{
    struct lp3944_led_data *led;

    led = container_of(work, struct lp3944_led_data, work);
    lp3944_led_set(led, led->status);
}

static int lp3944_configure(struct i2c_client *client,
                struct lp3944_data *data,
                struct lp3944_platform_data *pdata)
{
    int i, err = 0;

    for (i = 0; i < pdata->leds_size; i++) {
        struct lp3944_led *pled = &pdata->leds[i];
        struct lp3944_led_data *led = &data->leds[i];
        led->client = client;
        led->id = i;

        switch (pled->type) {

        case LP3944_LED_TYPE_LED:
        case LP3944_LED_TYPE_LED_INVERTED:
            led->type = pled->type;
            led->status = pled->status;
            led->ldev.name = pled->name;
            led->ldev.max_brightness = 1;
            led->ldev.brightness_set = lp3944_led_set_brightness;
            led->ldev.blink_set = lp3944_led_set_blink;
            led->ldev.flags = LED_CORE_SUSPENDRESUME;

            INIT_WORK(&led->work, lp3944_led_work);
            err = led_classdev_register(&client->dev, &led->ldev);
            if (err < 0) {
                dev_err(&client->dev,
                    "couldn't register LED %s\n",
                    led->ldev.name);
                goto exit;
            }

            /* to expose the default value to userspace */
            led->ldev.brightness = led->status;

            /* Set the default led status */
            err = lp3944_led_set(led, led->status);
            if (err < 0) {
                dev_err(&client->dev,
                    "%s couldn't set STATUS %d\n",
                    led->ldev.name, led->status);
                goto exit;
            }
            break;

        case LP3944_LED_TYPE_NONE:
        default:
            break;

        }
    }
    return 0;

exit:
    if (i > 0)
        for (i = i - 1; i >= 0; i--)
            switch (pdata->leds[i].type) {

            case LP3944_LED_TYPE_LED:
            case LP3944_LED_TYPE_LED_INVERTED:
                led_classdev_unregister(&data->leds[i].ldev);
                cancel_work_sync(&data->leds[i].work);
                break;

            case LP3944_LED_TYPE_NONE:
            default:
                break;
            }

    return err;
}

static int __devinit lp3944_probe(struct i2c_client *client,
                  const struct i2c_device_id *id)
{
    struct lp3944_platform_data *lp3944_pdata = client->dev.platform_data;
    struct lp3944_data *data;
    int err;

    if (lp3944_pdata == NULL) {
        dev_err(&client->dev, "no platform data\n");
        return -EINVAL;
    }

    /* Let's see whether this adapter can support what we need. */
    if (!i2c_check_functionality(client->adapter,
                I2C_FUNC_SMBUS_BYTE_DATA)) {
        dev_err(&client->dev, "insufficient functionality!\n");
        return -ENODEV;
    }

    data = devm_kzalloc(&client->dev, sizeof(struct lp3944_data),
            GFP_KERNEL);
    if (!data)
        return -ENOMEM;

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

    mutex_init(&data->lock);

    err = lp3944_configure(client, data, lp3944_pdata);
    if (err < 0)
        return err;

    dev_info(&client->dev, "lp3944 enabled\n");
    return 0;
}

static int __devexit lp3944_remove(struct i2c_client *client)
{
    struct lp3944_platform_data *pdata = client->dev.platform_data;
    struct lp3944_data *data = i2c_get_clientdata(client);
    int i;

    for (i = 0; i < pdata->leds_size; i++)
        switch (data->leds[i].type) {
        case LP3944_LED_TYPE_LED:
        case LP3944_LED_TYPE_LED_INVERTED:
            led_classdev_unregister(&data->leds[i].ldev);
            cancel_work_sync(&data->leds[i].work);
            break;

        case LP3944_LED_TYPE_NONE:
        default:
            break;
        }

    return 0;
}

/* lp3944 i2c driver struct */
static const struct i2c_device_id lp3944_id[] = {
    {"lp3944", 0},
    {}
};

MODULE_DEVICE_TABLE(i2c, lp3944_id);

static struct i2c_driver lp3944_driver = {
    .driver   = {
           .name = "lp3944",
    },
    .probe    = lp3944_probe,
    .remove   = __devexit_p(lp3944_remove),
    .id_table = lp3944_id,
};

module_i2c_driver(lp3944_driver);

MODULE_AUTHOR("Antonio Ospite <[email protected]>");
MODULE_DESCRIPTION("LP3944 Fun Light Chip");
MODULE_LICENSE("GPL");