leds-gpio.c

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/*
 * LEDs driver for GPIOs
 *
 * Copyright (C) 2007 8D Technologies inc.
 * Raphael Assenat <[email protected]>
 * Copyright (C) 2008 Freescale Semiconductor, Inc.
 *
 * 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.
 *
 */
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/platform_device.h>
#include <linux/gpio.h>
#include <linux/leds.h>
#include <linux/of_platform.h>
#include <linux/of_gpio.h>
#include <linux/slab.h>
#include <linux/workqueue.h>
#include <linux/module.h>
#include <linux/pinctrl/consumer.h>

struct gpio_led_data {
    struct led_classdev cdev;
    unsigned gpio;
    struct work_struct work;
    u8 new_level;
    u8 can_sleep;
    u8 active_low;
    u8 blinking;
    int (*platform_gpio_blink_set)(unsigned gpio, int state,
            unsigned long *delay_on, unsigned long *delay_off);
};

static void gpio_led_work(struct work_struct *work)
{
    struct gpio_led_data    *led_dat =
        container_of(work, struct gpio_led_data, work);

    if (led_dat->blinking) {
        led_dat->platform_gpio_blink_set(led_dat->gpio,
                         led_dat->new_level,
                         NULL, NULL);
        led_dat->blinking = 0;
    } else
        gpio_set_value_cansleep(led_dat->gpio, led_dat->new_level);
}

static void gpio_led_set(struct led_classdev *led_cdev,
    enum led_brightness value)
{
    struct gpio_led_data *led_dat =
        container_of(led_cdev, struct gpio_led_data, cdev);
    int level;

    if (value == LED_OFF)
        level = 0;
    else
        level = 1;

    if (led_dat->active_low)
        level = !level;

    /* Setting GPIOs with I2C/etc requires a task context, and we don't
     * seem to have a reliable way to know if we're already in one; so
     * let's just assume the worst.
     */
    if (led_dat->can_sleep) {
        led_dat->new_level = level;
        schedule_work(&led_dat->work);
    } else {
        if (led_dat->blinking) {
            led_dat->platform_gpio_blink_set(led_dat->gpio, level,
                             NULL, NULL);
            led_dat->blinking = 0;
        } else
            gpio_set_value(led_dat->gpio, level);
    }
}

static int gpio_blink_set(struct led_classdev *led_cdev,
    unsigned long *delay_on, unsigned long *delay_off)
{
    struct gpio_led_data *led_dat =
        container_of(led_cdev, struct gpio_led_data, cdev);

    led_dat->blinking = 1;
    return led_dat->platform_gpio_blink_set(led_dat->gpio, GPIO_LED_BLINK,
                        delay_on, delay_off);
}

static int __devinit create_gpio_led(const struct gpio_led *template,
    struct gpio_led_data *led_dat, struct device *parent,
    int (*blink_set)(unsigned, int, unsigned long *, unsigned long *))
{
    int ret, state;

    led_dat->gpio = -1;

    /* skip leds that aren't available */
    if (!gpio_is_valid(template->gpio)) {
        printk(KERN_INFO "Skipping unavailable LED gpio %d (%s)\n",
                template->gpio, template->name);
        return 0;
    }

    ret = gpio_request(template->gpio, template->name);
    if (ret < 0)
        return ret;

    led_dat->cdev.name = template->name;
    led_dat->cdev.default_trigger = template->default_trigger;
    led_dat->gpio = template->gpio;
    led_dat->can_sleep = gpio_cansleep(template->gpio);
    led_dat->active_low = template->active_low;
    led_dat->blinking = 0;
    if (blink_set) {
        led_dat->platform_gpio_blink_set = blink_set;
        led_dat->cdev.blink_set = gpio_blink_set;
    }
    led_dat->cdev.brightness_set = gpio_led_set;
    if (template->default_state == LEDS_GPIO_DEFSTATE_KEEP)
        state = !!gpio_get_value_cansleep(led_dat->gpio) ^ led_dat->active_low;
    else
        state = (template->default_state == LEDS_GPIO_DEFSTATE_ON);
    led_dat->cdev.brightness = state ? LED_FULL : LED_OFF;
    if (!template->retain_state_suspended)
        led_dat->cdev.flags |= LED_CORE_SUSPENDRESUME;

    ret = gpio_direction_output(led_dat->gpio, led_dat->active_low ^ state);
    if (ret < 0)
        goto err;
        
    INIT_WORK(&led_dat->work, gpio_led_work);

    ret = led_classdev_register(parent, &led_dat->cdev);
    if (ret < 0)
        goto err;

    return 0;
err:
    gpio_free(led_dat->gpio);
    return ret;
}

static void delete_gpio_led(struct gpio_led_data *led)
{
    if (!gpio_is_valid(led->gpio))
        return;
    led_classdev_unregister(&led->cdev);
    cancel_work_sync(&led->work);
    gpio_free(led->gpio);
}

struct gpio_leds_priv {
    int num_leds;
    struct gpio_led_data leds[];
};

static inline int sizeof_gpio_leds_priv(int num_leds)
{
    return sizeof(struct gpio_leds_priv) +
        (sizeof(struct gpio_led_data) * num_leds);
}

/* Code to create from OpenFirmware platform devices */
#ifdef CONFIG_OF_GPIO
static struct gpio_leds_priv * __devinit gpio_leds_create_of(struct platform_device *pdev)
{
    struct device_node *np = pdev->dev.of_node, *child;
    struct gpio_leds_priv *priv;
    int count, ret;

    /* count LEDs in this device, so we know how much to allocate */
    count = of_get_child_count(np);
    if (!count)
        return NULL;

    priv = devm_kzalloc(&pdev->dev, sizeof_gpio_leds_priv(count),
            GFP_KERNEL);
    if (!priv)
        return NULL;

    for_each_child_of_node(np, child) {
        struct gpio_led led = {};
        enum of_gpio_flags flags;
        const char *state;

        led.gpio = of_get_gpio_flags(child, 0, &flags);
        led.active_low = flags & OF_GPIO_ACTIVE_LOW;
        led.name = of_get_property(child, "label", NULL) ? : child->name;
        led.default_trigger =
            of_get_property(child, "linux,default-trigger", NULL);
        state = of_get_property(child, "default-state", NULL);
        if (state) {
            if (!strcmp(state, "keep"))
                led.default_state = LEDS_GPIO_DEFSTATE_KEEP;
            else if (!strcmp(state, "on"))
                led.default_state = LEDS_GPIO_DEFSTATE_ON;
            else
                led.default_state = LEDS_GPIO_DEFSTATE_OFF;
        }

        ret = create_gpio_led(&led, &priv->leds[priv->num_leds++],
                      &pdev->dev, NULL);
        if (ret < 0) {
            of_node_put(child);
            goto err;
        }
    }

    return priv;

err:
    for (count = priv->num_leds - 2; count >= 0; count--)
        delete_gpio_led(&priv->leds[count]);
    return NULL;
}

static const struct of_device_id of_gpio_leds_match[] = {
    { .compatible = "gpio-leds", },
    {},
};
#else /* CONFIG_OF_GPIO */
static struct gpio_leds_priv * __devinit gpio_leds_create_of(struct platform_device *pdev)
{
    return NULL;
}
#endif /* CONFIG_OF_GPIO */


static int __devinit gpio_led_probe(struct platform_device *pdev)
{
    struct gpio_led_platform_data *pdata = pdev->dev.platform_data;
    struct gpio_leds_priv *priv;
    struct pinctrl *pinctrl;
    int i, ret = 0;

    pinctrl = devm_pinctrl_get_select_default(&pdev->dev);
    if (IS_ERR(pinctrl))
        dev_warn(&pdev->dev,
            "pins are not configured from the driver\n");

    if (pdata && pdata->num_leds) {
        priv = devm_kzalloc(&pdev->dev,
                sizeof_gpio_leds_priv(pdata->num_leds),
                    GFP_KERNEL);
        if (!priv)
            return -ENOMEM;

        priv->num_leds = pdata->num_leds;
        for (i = 0; i < priv->num_leds; i++) {
            ret = create_gpio_led(&pdata->leds[i],
                          &priv->leds[i],
                          &pdev->dev, pdata->gpio_blink_set);
            if (ret < 0) {
                /* On failure: unwind the led creations */
                for (i = i - 1; i >= 0; i--)
                    delete_gpio_led(&priv->leds[i]);
                return ret;
            }
        }
    } else {
        priv = gpio_leds_create_of(pdev);
        if (!priv)
            return -ENODEV;
    }

    platform_set_drvdata(pdev, priv);

    return 0;
}

static int __devexit gpio_led_remove(struct platform_device *pdev)
{
    struct gpio_leds_priv *priv = platform_get_drvdata(pdev);
    int i;

    for (i = 0; i < priv->num_leds; i++)
        delete_gpio_led(&priv->leds[i]);

    platform_set_drvdata(pdev, NULL);

    return 0;
}

static struct platform_driver gpio_led_driver = {
    .probe      = gpio_led_probe,
    .remove     = __devexit_p(gpio_led_remove),
    .driver     = {
        .name   = "leds-gpio",
        .owner  = THIS_MODULE,
        .of_match_table = of_match_ptr(of_gpio_leds_match),
    },
};

module_platform_driver(gpio_led_driver);

MODULE_AUTHOR("Raphael Assenat <[email protected]>, Trent Piepho <[email protected]>");
MODULE_DESCRIPTION("GPIO LED driver");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:leds-gpio");