1 // SPDX-License-Identifier: GPL-2.0
2 // Copyright (c) 2009,2018 Daniel Mack <daniel@zonque.org>
4 #include <linux/kernel.h>
5 #include <linux/platform_device.h>
6 #include <linux/leds.h>
7 #include <linux/delay.h>
8 #include <linux/gpio/consumer.h>
9 #include <linux/slab.h>
10 #include <linux/module.h>
13 #define LED_LT3593_NAME "lt3593"
15 struct lt3593_led_data {
16 struct led_classdev cdev;
17 struct gpio_desc *gpiod;
20 static int lt3593_led_set(struct led_classdev *led_cdev,
21 enum led_brightness value)
23 struct lt3593_led_data *led_dat =
24 container_of(led_cdev, struct lt3593_led_data, cdev);
28 * The LT3593 resets its internal current level register to the maximum
29 * level on the first falling edge on the control pin. Each following
30 * falling edge decreases the current level by 625uA. Up to 32 pulses
31 * can be sent, so the maximum power reduction is 20mA.
32 * After a timeout of 128us, the value is taken from the register and
33 * applied is to the output driver.
37 gpiod_set_value_cansleep(led_dat->gpiod, 0);
41 pulses = 32 - (value * 32) / 255;
44 gpiod_set_value_cansleep(led_dat->gpiod, 0);
46 gpiod_set_value_cansleep(led_dat->gpiod, 1);
50 gpiod_set_value_cansleep(led_dat->gpiod, 1);
53 gpiod_set_value_cansleep(led_dat->gpiod, 0);
55 gpiod_set_value_cansleep(led_dat->gpiod, 1);
62 static int lt3593_led_probe(struct platform_device *pdev)
64 struct device *dev = &pdev->dev;
65 struct lt3593_led_data *led_data;
66 struct fwnode_handle *child;
67 int ret, state = LEDS_GPIO_DEFSTATE_OFF;
68 struct led_init_data init_data = {};
71 if (!dev_of_node(dev))
74 led_data = devm_kzalloc(dev, sizeof(*led_data), GFP_KERNEL);
78 if (device_get_child_node_count(dev) != 1) {
79 dev_err(dev, "Device must have exactly one LED sub-node.");
83 led_data->gpiod = devm_gpiod_get(dev, "lltc,ctrl", 0);
84 if (IS_ERR(led_data->gpiod))
85 return PTR_ERR(led_data->gpiod);
87 child = device_get_next_child_node(dev, NULL);
89 if (!fwnode_property_read_string(child, "default-state", &tmp)) {
90 if (!strcmp(tmp, "on"))
91 state = LEDS_GPIO_DEFSTATE_ON;
94 led_data->cdev.brightness_set_blocking = lt3593_led_set;
95 led_data->cdev.brightness = state ? LED_FULL : LED_OFF;
97 init_data.fwnode = child;
98 init_data.devicename = LED_LT3593_NAME;
99 init_data.default_label = ":";
101 ret = devm_led_classdev_register_ext(dev, &led_data->cdev, &init_data);
103 fwnode_handle_put(child);
107 platform_set_drvdata(pdev, led_data);
112 static const struct of_device_id of_lt3593_leds_match[] = {
113 { .compatible = "lltc,lt3593", },
116 MODULE_DEVICE_TABLE(of, of_lt3593_leds_match);
118 static struct platform_driver lt3593_led_driver = {
119 .probe = lt3593_led_probe,
121 .name = "leds-lt3593",
122 .of_match_table = of_match_ptr(of_lt3593_leds_match),
126 module_platform_driver(lt3593_led_driver);
128 MODULE_AUTHOR("Daniel Mack <daniel@zonque.org>");
129 MODULE_DESCRIPTION("LED driver for LT3593 controllers");
130 MODULE_LICENSE("GPL v2");
131 MODULE_ALIAS("platform:leds-lt3593");