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-only
2/*
3 * linux/drivers/leds-pwm.c
4 *
5 * simple PWM based LED control
6 *
7 * Copyright 2009 Luotao Fu @ Pengutronix (l.fu@pengutronix.de)
8 *
9 * based on leds-gpio.c by Raphael Assenat <raph@8d.com>
10 */
11
12#include <linux/module.h>
13#include <linux/kernel.h>
14#include <linux/platform_device.h>
15#include <linux/of_platform.h>
16#include <linux/leds.h>
17#include <linux/err.h>
18#include <linux/pwm.h>
19#include <linux/slab.h>
20
21struct led_pwm {
22 const char *name;
23 const char *default_trigger;
24 u8 active_low;
25 unsigned int max_brightness;
26};
27
28struct led_pwm_platform_data {
29 int num_leds;
30 struct led_pwm *leds;
31};
32
33struct led_pwm_data {
34 struct led_classdev cdev;
35 struct pwm_device *pwm;
36 struct pwm_state pwmstate;
37 unsigned int active_low;
38};
39
40struct led_pwm_priv {
41 int num_leds;
42 struct led_pwm_data leds[];
43};
44
45static int led_pwm_set(struct led_classdev *led_cdev,
46 enum led_brightness brightness)
47{
48 struct led_pwm_data *led_dat =
49 container_of(led_cdev, struct led_pwm_data, cdev);
50 unsigned int max = led_dat->cdev.max_brightness;
51 unsigned long long duty = led_dat->pwmstate.period;
52
53 duty *= brightness;
54 do_div(duty, max);
55
56 if (led_dat->active_low)
57 duty = led_dat->pwmstate.period - duty;
58
59 led_dat->pwmstate.duty_cycle = duty;
60 led_dat->pwmstate.enabled = duty > 0;
61 return pwm_apply_state(led_dat->pwm, &led_dat->pwmstate);
62}
63
64static int led_pwm_add(struct device *dev, struct led_pwm_priv *priv,
65 struct led_pwm *led, struct fwnode_handle *fwnode)
66{
67 struct led_pwm_data *led_data = &priv->leds[priv->num_leds];
68 int ret;
69
70 led_data->active_low = led->active_low;
71 led_data->cdev.name = led->name;
72 led_data->cdev.default_trigger = led->default_trigger;
73 led_data->cdev.brightness = LED_OFF;
74 led_data->cdev.max_brightness = led->max_brightness;
75 led_data->cdev.flags = LED_CORE_SUSPENDRESUME;
76
77 if (fwnode)
78 led_data->pwm = devm_fwnode_pwm_get(dev, fwnode, NULL);
79 else
80 led_data->pwm = devm_pwm_get(dev, led->name);
81 if (IS_ERR(led_data->pwm)) {
82 ret = PTR_ERR(led_data->pwm);
83 if (ret != -EPROBE_DEFER)
84 dev_err(dev, "unable to request PWM for %s: %d\n",
85 led->name, ret);
86 return ret;
87 }
88
89 led_data->cdev.brightness_set_blocking = led_pwm_set;
90
91 pwm_init_state(led_data->pwm, &led_data->pwmstate);
92
93 ret = devm_led_classdev_register(dev, &led_data->cdev);
94 if (ret) {
95 dev_err(dev, "failed to register PWM led for %s: %d\n",
96 led->name, ret);
97 return ret;
98 }
99
100 ret = led_pwm_set(&led_data->cdev, led_data->cdev.brightness);
101 if (ret) {
102 dev_err(dev, "failed to set led PWM value for %s: %d",
103 led->name, ret);
104 return ret;
105 }
106
107 priv->num_leds++;
108 return 0;
109}
110
111static int led_pwm_create_fwnode(struct device *dev, struct led_pwm_priv *priv)
112{
113 struct fwnode_handle *fwnode;
114 struct led_pwm led;
115 int ret = 0;
116
117 memset(&led, 0, sizeof(led));
118
119 device_for_each_child_node(dev, fwnode) {
120 ret = fwnode_property_read_string(fwnode, "label", &led.name);
121 if (ret && is_of_node(fwnode))
122 led.name = to_of_node(fwnode)->name;
123
124 if (!led.name) {
125 fwnode_handle_put(fwnode);
126 return -EINVAL;
127 }
128
129 fwnode_property_read_string(fwnode, "linux,default-trigger",
130 &led.default_trigger);
131
132 led.active_low = fwnode_property_read_bool(fwnode,
133 "active-low");
134 fwnode_property_read_u32(fwnode, "max-brightness",
135 &led.max_brightness);
136
137 ret = led_pwm_add(dev, priv, &led, fwnode);
138 if (ret) {
139 fwnode_handle_put(fwnode);
140 break;
141 }
142 }
143
144 return ret;
145}
146
147static int led_pwm_probe(struct platform_device *pdev)
148{
149 struct led_pwm_platform_data *pdata = dev_get_platdata(&pdev->dev);
150 struct led_pwm_priv *priv;
151 int count, i;
152 int ret = 0;
153
154 if (pdata)
155 count = pdata->num_leds;
156 else
157 count = device_get_child_node_count(&pdev->dev);
158
159 if (!count)
160 return -EINVAL;
161
162 priv = devm_kzalloc(&pdev->dev, struct_size(priv, leds, count),
163 GFP_KERNEL);
164 if (!priv)
165 return -ENOMEM;
166
167 if (pdata) {
168 for (i = 0; i < count; i++) {
169 ret = led_pwm_add(&pdev->dev, priv, &pdata->leds[i],
170 NULL);
171 if (ret)
172 break;
173 }
174 } else {
175 ret = led_pwm_create_fwnode(&pdev->dev, priv);
176 }
177
178 if (ret)
179 return ret;
180
181 platform_set_drvdata(pdev, priv);
182
183 return 0;
184}
185
186static const struct of_device_id of_pwm_leds_match[] = {
187 { .compatible = "pwm-leds", },
188 {},
189};
190MODULE_DEVICE_TABLE(of, of_pwm_leds_match);
191
192static struct platform_driver led_pwm_driver = {
193 .probe = led_pwm_probe,
194 .driver = {
195 .name = "leds_pwm",
196 .of_match_table = of_pwm_leds_match,
197 },
198};
199
200module_platform_driver(led_pwm_driver);
201
202MODULE_AUTHOR("Luotao Fu <l.fu@pengutronix.de>");
203MODULE_DESCRIPTION("generic PWM LED driver");
204MODULE_LICENSE("GPL v2");
205MODULE_ALIAS("platform:leds-pwm");