aboutsummaryrefslogtreecommitdiff
path: root/drivers/leds/leds-lt3593.c
blob: 83e8e58d81cb8b20df2273889771d75ed8b24d12 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
// 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.h>
#include <linux/gpio/consumer.h>
#include <linux/slab.h>
#include <linux/module.h>
#include <linux/of.h>
#include <uapi/linux/uleds.h>

struct lt3593_led_data {
	char name[LED_MAX_NAME_SIZE];
	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;
	const char *tmp;

	if (!dev->of_node)
		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);

	ret = fwnode_property_read_string(child, "label", &tmp);
	if (ret < 0)
		snprintf(led_data->name, sizeof(led_data->name),
			 "lt3593::");
	else
		snprintf(led_data->name, sizeof(led_data->name),
			 "lt3593:%s", tmp);

	fwnode_property_read_string(child, "linux,default-trigger",
				    &led_data->cdev.default_trigger);

	if (!fwnode_property_read_string(child, "default-state", &tmp)) {
		if (!strcmp(tmp, "on"))
			state = LEDS_GPIO_DEFSTATE_ON;
	}

	led_data->cdev.name = led_data->name;
	led_data->cdev.brightness_set_blocking = lt3593_led_set;
	led_data->cdev.brightness = state ? LED_FULL : LED_OFF;

	ret = devm_led_classdev_register(dev, &led_data->cdev);
	if (ret < 0) {
		fwnode_handle_put(child);
		return ret;
	}

	led_data->cdev.dev->of_node = dev->of_node;
	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");