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// SPDX-License-Identifier: GPL-2.0
// Copyright (c) 2009,2018 Daniel Mack <daniel@zonque.org>
#include <linux/kernel.h>
#include <linux/platform_device.h>
#include <linux/leds.h>
#include <linux/delay.h>
#include <linux/gpio/consumer.h>
#include <linux/slab.h>
#include <linux/module.h>
#include <linux/of.h>
#define LED_LT3593_NAME "lt3593"
struct lt3593_led_data {
struct led_classdev cdev;
struct gpio_desc *gpiod;
};
static int 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);
int pulses;
/*
* 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 (value == 0) {
gpiod_set_value_cansleep(led_dat->gpiod, 0);
return 0;
}
pulses = 32 - (value * 32) / 255;
if (pulses == 0) {
gpiod_set_value_cansleep(led_dat->gpiod, 0);
mdelay(1);
gpiod_set_value_cansleep(led_dat->gpiod, 1);
return 0;
}
gpiod_set_value_cansleep(led_dat->gpiod, 1);
while (pulses--) {
gpiod_set_value_cansleep(led_dat->gpiod, 0);
udelay(1);
gpiod_set_value_cansleep(led_dat->gpiod, 1);
udelay(1);
}
return 0;
}
static int lt3593_led_probe(struct platform_device *pdev)
{
struct device *dev = &pdev->dev;
struct lt3593_led_data *led_data;
struct fwnode_handle *child;
int ret, state = LEDS_GPIO_DEFSTATE_OFF;
struct led_init_data init_data = {};
const char *tmp;
if (!dev_of_node(dev))
return -ENODEV;
led_data = devm_kzalloc(dev, sizeof(*led_data), GFP_KERNEL);
if (!led_data)
return -ENOMEM;
if (device_get_child_node_count(dev) != 1) {
dev_err(dev, "Device must have exactly one LED sub-node.");
return -EINVAL;
}
led_data->gpiod = devm_gpiod_get(dev, "lltc,ctrl", 0);
if (IS_ERR(led_data->gpiod))
return PTR_ERR(led_data->gpiod);
child = device_get_next_child_node(dev, NULL);
if (!fwnode_property_read_string(child, "default-state", &tmp)) {
if (!strcmp(tmp, "on"))
state = LEDS_GPIO_DEFSTATE_ON;
}
led_data->cdev.brightness_set_blocking = lt3593_led_set;
led_data->cdev.brightness = state ? LED_FULL : LED_OFF;
init_data.fwnode = child;
init_data.devicename = LED_LT3593_NAME;
init_data.default_label = ":";
ret = devm_led_classdev_register_ext(dev, &led_data->cdev, &init_data);
fwnode_handle_put(child);
if (ret < 0)
return ret;
platform_set_drvdata(pdev, led_data);
return 0;
}
static const struct of_device_id of_lt3593_leds_match[] = {
{ .compatible = "lltc,lt3593", },
{},
};
MODULE_DEVICE_TABLE(of, of_lt3593_leds_match);
static struct platform_driver lt3593_led_driver = {
.probe = lt3593_led_probe,
.driver = {
.name = "leds-lt3593",
.of_match_table = of_match_ptr(of_lt3593_leds_match),
},
};
module_platform_driver(lt3593_led_driver);
MODULE_AUTHOR("Daniel Mack <daniel@zonque.org>");
MODULE_DESCRIPTION("LED driver for LT3593 controllers");
MODULE_LICENSE("GPL v2");
MODULE_ALIAS("platform:leds-lt3593");
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