1// SPDX-License-Identifier: GPL-2.0
2// Copyright (c) 2009,2018 Daniel Mack <daniel@zonque.org>
3
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>
11#include <linux/of.h>
12
13#define LED_LT3593_NAME "lt3593"
14
15struct lt3593_led_data {
16	struct led_classdev cdev;
17	struct gpio_desc *gpiod;
18};
19
20static int lt3593_led_set(struct led_classdev *led_cdev,
21			   enum led_brightness value)
22{
23	struct lt3593_led_data *led_dat =
24		container_of(led_cdev, struct lt3593_led_data, cdev);
25	int pulses;
26
27	/*
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.
34	 */
35
36	if (value == 0) {
37		gpiod_set_value_cansleep(led_dat->gpiod, 0);
38		return 0;
39	}
40
41	pulses = 32 - (value * 32) / 255;
42
43	if (pulses == 0) {
44		gpiod_set_value_cansleep(led_dat->gpiod, 0);
45		mdelay(1);
46		gpiod_set_value_cansleep(led_dat->gpiod, 1);
47		return 0;
48	}
49
50	gpiod_set_value_cansleep(led_dat->gpiod, 1);
51
52	while (pulses--) {
53		gpiod_set_value_cansleep(led_dat->gpiod, 0);
54		udelay(1);
55		gpiod_set_value_cansleep(led_dat->gpiod, 1);
56		udelay(1);
57	}
58
59	return 0;
60}
61
62static int lt3593_led_probe(struct platform_device *pdev)
63{
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 = {};
69	const char *tmp;
70
71	if (!dev_of_node(dev))
72		return -ENODEV;
73
74	led_data = devm_kzalloc(dev, sizeof(*led_data), GFP_KERNEL);
75	if (!led_data)
76		return -ENOMEM;
77
78	if (device_get_child_node_count(dev) != 1) {
79		dev_err(dev, "Device must have exactly one LED sub-node.");
80		return -EINVAL;
81	}
82
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);
86
87	child = device_get_next_child_node(dev, NULL);
88
89	if (!fwnode_property_read_string(child, "default-state", &tmp)) {
90		if (!strcmp(tmp, "on"))
91			state = LEDS_GPIO_DEFSTATE_ON;
92	}
93
94	led_data->cdev.brightness_set_blocking = lt3593_led_set;
95	led_data->cdev.brightness = state ? LED_FULL : LED_OFF;
96
97	init_data.fwnode = child;
98	init_data.devicename = LED_LT3593_NAME;
99	init_data.default_label = ":";
100
101	ret = devm_led_classdev_register_ext(dev, &led_data->cdev, &init_data);
102	fwnode_handle_put(child);
103	if (ret < 0)
104		return ret;
105
106	platform_set_drvdata(pdev, led_data);
107
108	return 0;
109}
110
111static const struct of_device_id of_lt3593_leds_match[] = {
112	{ .compatible = "lltc,lt3593", },
113	{},
114};
115MODULE_DEVICE_TABLE(of, of_lt3593_leds_match);
116
117static struct platform_driver lt3593_led_driver = {
118	.probe		= lt3593_led_probe,
119	.driver		= {
120		.name	= "leds-lt3593",
121		.of_match_table = of_match_ptr(of_lt3593_leds_match),
122	},
123};
124
125module_platform_driver(lt3593_led_driver);
126
127MODULE_AUTHOR("Daniel Mack <daniel@zonque.org>");
128MODULE_DESCRIPTION("LED driver for LT3593 controllers");
129MODULE_LICENSE("GPL v2");
130MODULE_ALIAS("platform:leds-lt3593");
131