tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
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.h>
9#include <linux/gpio/consumer.h>
10#include <linux/slab.h>
11#include <linux/module.h>
12#include <linux/of.h>
13#include <uapi/linux/uleds.h>
14
15struct lt3593_led_data {
16 char name[LED_MAX_NAME_SIZE];
17 struct led_classdev cdev;
18 struct gpio_desc *gpiod;
19};
20
21static int lt3593_led_set(struct led_classdev *led_cdev,
22 enum led_brightness value)
23{
24 struct lt3593_led_data *led_dat =
25 container_of(led_cdev, struct lt3593_led_data, cdev);
26 int pulses;
27
28 /*
29 * The LT3593 resets its internal current level register to the maximum
30 * level on the first falling edge on the control pin. Each following
31 * falling edge decreases the current level by 625uA. Up to 32 pulses
32 * can be sent, so the maximum power reduction is 20mA.
33 * After a timeout of 128us, the value is taken from the register and
34 * applied is to the output driver.
35 */
36
37 if (value == 0) {
38 gpiod_set_value_cansleep(led_dat->gpiod, 0);
39 return 0;
40 }
41
42 pulses = 32 - (value * 32) / 255;
43
44 if (pulses == 0) {
45 gpiod_set_value_cansleep(led_dat->gpiod, 0);
46 mdelay(1);
47 gpiod_set_value_cansleep(led_dat->gpiod, 1);
48 return 0;
49 }
50
51 gpiod_set_value_cansleep(led_dat->gpiod, 1);
52
53 while (pulses--) {
54 gpiod_set_value_cansleep(led_dat->gpiod, 0);
55 udelay(1);
56 gpiod_set_value_cansleep(led_dat->gpiod, 1);
57 udelay(1);
58 }
59
60 return 0;
61}
62
63static int lt3593_led_probe(struct platform_device *pdev)
64{
65 struct device *dev = &pdev->dev;
66 struct lt3593_led_data *led_data;
67 struct fwnode_handle *child;
68 int ret, state = LEDS_GPIO_DEFSTATE_OFF;
69 const char *tmp;
70
71 if (!dev->of_node)
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 ret = fwnode_property_read_string(child, "label", &tmp);
90 if (ret < 0)
91 snprintf(led_data->name, sizeof(led_data->name),
92 "lt3593::");
93 else
94 snprintf(led_data->name, sizeof(led_data->name),
95 "lt3593:%s", tmp);
96
97 fwnode_property_read_string(child, "linux,default-trigger",
98 &led_data->cdev.default_trigger);
99
100 if (!fwnode_property_read_string(child, "default-state", &tmp)) {
101 if (!strcmp(tmp, "on"))
102 state = LEDS_GPIO_DEFSTATE_ON;
103 }
104
105 led_data->cdev.name = led_data->name;
106 led_data->cdev.brightness_set_blocking = lt3593_led_set;
107 led_data->cdev.brightness = state ? LED_FULL : LED_OFF;
108
109 ret = devm_led_classdev_register(dev, &led_data->cdev);
110 if (ret < 0) {
111 fwnode_handle_put(child);
112 return ret;
113 }
114
115 led_data->cdev.dev->of_node = dev->of_node;
116 platform_set_drvdata(pdev, led_data);
117
118 return 0;
119}
120
121static const struct of_device_id of_lt3593_leds_match[] = {
122 { .compatible = "lltc,lt3593", },
123 {},
124};
125MODULE_DEVICE_TABLE(of, of_lt3593_leds_match);
126
127static struct platform_driver lt3593_led_driver = {
128 .probe = lt3593_led_probe,
129 .driver = {
130 .name = "leds-lt3593",
131 .of_match_table = of_match_ptr(of_lt3593_leds_match),
132 },
133};
134
135module_platform_driver(lt3593_led_driver);
136
137MODULE_AUTHOR("Daniel Mack <daniel@zonque.org>");
138MODULE_DESCRIPTION("LED driver for LT3593 controllers");
139MODULE_LICENSE("GPL v2");
140MODULE_ALIAS("platform:leds-lt3593");