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/mod_devicetable.h> |
11 | #include <linux/module.h> |
12 | #include <linux/property.h> |
13 | |
14 | #define LED_LT3593_NAME "lt3593" |
15 | |
16 | struct lt3593_led_data { |
17 | struct led_classdev cdev; |
18 | struct gpio_desc *gpiod; |
19 | }; |
20 | |
21 | static 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(desc: led_dat->gpiod, value: 0); |
39 | return 0; |
40 | } |
41 | |
42 | pulses = 32 - (value * 32) / 255; |
43 | |
44 | if (pulses == 0) { |
45 | gpiod_set_value_cansleep(desc: led_dat->gpiod, value: 0); |
46 | mdelay(1); |
47 | gpiod_set_value_cansleep(desc: led_dat->gpiod, value: 1); |
48 | return 0; |
49 | } |
50 | |
51 | gpiod_set_value_cansleep(desc: led_dat->gpiod, value: 1); |
52 | |
53 | while (pulses--) { |
54 | gpiod_set_value_cansleep(desc: led_dat->gpiod, value: 0); |
55 | udelay(1); |
56 | gpiod_set_value_cansleep(desc: led_dat->gpiod, value: 1); |
57 | udelay(1); |
58 | } |
59 | |
60 | return 0; |
61 | } |
62 | |
63 | static 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 | struct led_init_data init_data = {}; |
70 | const char *tmp; |
71 | |
72 | led_data = devm_kzalloc(dev, size: sizeof(*led_data), GFP_KERNEL); |
73 | if (!led_data) |
74 | return -ENOMEM; |
75 | |
76 | if (device_get_child_node_count(dev) != 1) { |
77 | dev_err(dev, "Device must have exactly one LED sub-node." ); |
78 | return -EINVAL; |
79 | } |
80 | |
81 | led_data->gpiod = devm_gpiod_get(dev, con_id: "lltc,ctrl" , flags: 0); |
82 | if (IS_ERR(ptr: led_data->gpiod)) |
83 | return PTR_ERR(ptr: led_data->gpiod); |
84 | |
85 | child = device_get_next_child_node(dev, NULL); |
86 | |
87 | if (!fwnode_property_read_string(fwnode: child, propname: "default-state" , val: &tmp)) { |
88 | if (!strcmp(tmp, "on" )) |
89 | state = LEDS_GPIO_DEFSTATE_ON; |
90 | } |
91 | |
92 | led_data->cdev.brightness_set_blocking = lt3593_led_set; |
93 | led_data->cdev.brightness = state ? LED_FULL : LED_OFF; |
94 | |
95 | init_data.fwnode = child; |
96 | init_data.devicename = LED_LT3593_NAME; |
97 | init_data.default_label = ":" ; |
98 | |
99 | ret = devm_led_classdev_register_ext(parent: dev, led_cdev: &led_data->cdev, init_data: &init_data); |
100 | fwnode_handle_put(fwnode: child); |
101 | if (ret < 0) |
102 | return ret; |
103 | |
104 | platform_set_drvdata(pdev, data: led_data); |
105 | |
106 | return 0; |
107 | } |
108 | |
109 | static const struct of_device_id of_lt3593_leds_match[] = { |
110 | { .compatible = "lltc,lt3593" , }, |
111 | {}, |
112 | }; |
113 | MODULE_DEVICE_TABLE(of, of_lt3593_leds_match); |
114 | |
115 | static struct platform_driver lt3593_led_driver = { |
116 | .probe = lt3593_led_probe, |
117 | .driver = { |
118 | .name = "leds-lt3593" , |
119 | .of_match_table = of_lt3593_leds_match, |
120 | }, |
121 | }; |
122 | |
123 | module_platform_driver(lt3593_led_driver); |
124 | |
125 | MODULE_AUTHOR("Daniel Mack <daniel@zonque.org>" ); |
126 | MODULE_DESCRIPTION("LED driver for LT3593 controllers" ); |
127 | MODULE_LICENSE("GPL v2" ); |
128 | MODULE_ALIAS("platform:leds-lt3593" ); |
129 | |