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/*
* LEDs driver for LT3593 controllers
*
* See the datasheet at http://cds.linear.com/docs/Datasheet/3593f.pdf
*
* Copyright (c) 2009 Daniel Mack <daniel@caiaq.de>
*
* Based on leds-gpio.c,
*
* Copyright (C) 2007 8D Technologies inc.
* Raphael Assenat <raph@8d.com>
* 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/leds.h>
#include <linux/workqueue.h>
#include <linux/delay.h>
#include <linux/gpio.h>
#include <linux/slab.h>
#include <linux/module.h>
struct lt3593_led_data {
struct led_classdev cdev;
unsigned gpio;
struct work_struct work;
u8 new_level;
};
static void lt3593_led_work(struct work_struct *work)
{
int pulses;
struct lt3593_led_data *led_dat =
container_of(work, struct lt3593_led_data, work);
/*
* The LT3593 resets its internal current level register to the maximum
* level on the first falling edge on the control pin. Each following
* falling edge decreases the current level by 625uA. Up to 32 pulses
* can be sent, so the maximum power reduction is 20mA.
* After a timeout of 128us, the value is taken from the register and
* applied is to the output driver.
*/
if (led_dat->new_level == 0) {
gpio_set_value_cansleep(led_dat->gpio, 0);
return;
}
pulses = 32 - (led_dat->new_level * 32) / 255;
if (pulses == 0) {
gpio_set_value_cansleep(led_dat->gpio, 0);
mdelay(1);
gpio_set_value_cansleep(led_dat->gpio, 1);
return;
}
gpio_set_value_cansleep(led_dat->gpio, 1);
while (pulses--) {
gpio_set_value_cansleep(led_dat->gpio, 0);
udelay(1);
gpio_set_value_cansleep(led_dat->gpio, 1);
udelay(1);
}
}
static void lt3593_led_set(struct led_classdev *led_cdev,
enum led_brightness value)
{
struct lt3593_led_data *led_dat =
container_of(led_cdev, struct lt3593_led_data, cdev);
led_dat->new_level = value;
schedule_work(&led_dat->work);
}
static int create_lt3593_led(const struct gpio_led *template,
struct lt3593_led_data *led_dat, struct device *parent)
{
int ret, state;
/* skip leds on GPIOs that aren't available */
if (!gpio_is_valid(template->gpio)) {
dev_info(parent, "%s: skipping unavailable LT3593 LED at gpio %d (%s)\n",
KBUILD_MODNAME, template->gpio, template->name);
return 0;
}
led_dat->cdev.name = template->name;
led_dat->cdev.default_trigger = template->default_trigger;
led_dat->gpio = template->gpio;
led_dat->cdev.brightness_set = lt3593_led_set;
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 = devm_gpio_request_one(parent, template->gpio, state ?
GPIOF_OUT_INIT_HIGH : GPIOF_OUT_INIT_LOW,
template->name);
if (ret < 0)
return ret;
INIT_WORK(&led_dat->work, lt3593_led_work);
ret = led_classdev_register(parent, &led_dat->cdev);
if (ret < 0)
return ret;
dev_info(parent, "%s: registered LT3593 LED '%s' at GPIO %d\n",
KBUILD_MODNAME, template->name, template->gpio);
return 0;
}
static void delete_lt3593_led(struct lt3593_led_data *led)
{
if (!gpio_is_valid(led->gpio))
return;
led_classdev_unregister(&led->cdev);
cancel_work_sync(&led->work);
}
static int lt3593_led_probe(struct platform_device *pdev)
{
struct gpio_led_platform_data *pdata = pdev->dev.platform_data;
struct lt3593_led_data *leds_data;
int i, ret = 0;
if (!pdata)
return -EBUSY;
leds_data = devm_kzalloc(&pdev->dev,
sizeof(struct lt3593_led_data) * pdata->num_leds,
GFP_KERNEL);
if (!leds_data)
return -ENOMEM;
for (i = 0; i < pdata->num_leds; i++) {
ret = create_lt3593_led(&pdata->leds[i], &leds_data[i],
&pdev->dev);
if (ret < 0)
goto err;
}
platform_set_drvdata(pdev, leds_data);
return 0;
err:
for (i = i - 1; i >= 0; i--)
delete_lt3593_led(&leds_data[i]);
return ret;
}
static int lt3593_led_remove(struct platform_device *pdev)
{
int i;
struct gpio_led_platform_data *pdata = pdev->dev.platform_data;
struct lt3593_led_data *leds_data;
leds_data = platform_get_drvdata(pdev);
for (i = 0; i < pdata->num_leds; i++)
delete_lt3593_led(&leds_data[i]);
return 0;
}
static struct platform_driver lt3593_led_driver = {
.probe = lt3593_led_probe,
.remove = lt3593_led_remove,
.driver = {
.name = "leds-lt3593",
.owner = THIS_MODULE,
},
};
module_platform_driver(lt3593_led_driver);
MODULE_AUTHOR("Daniel Mack <daniel@caiaq.de>");
MODULE_DESCRIPTION("LED driver for LT3593 controllers");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:leds-lt3593");
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