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/leds_pwm.h>
20#include <linux/slab.h>
21
22struct led_pwm_data {
23 struct led_classdev cdev;
24 struct pwm_device *pwm;
25 unsigned int active_low;
26 unsigned int period;
27 int duty;
28};
29
30struct led_pwm_priv {
31 int num_leds;
32 struct led_pwm_data leds[0];
33};
34
35static void __led_pwm_set(struct led_pwm_data *led_dat)
36{
37 int new_duty = led_dat->duty;
38
39 pwm_config(led_dat->pwm, new_duty, led_dat->period);
40
41 if (new_duty == 0)
42 pwm_disable(led_dat->pwm);
43 else
44 pwm_enable(led_dat->pwm);
45}
46
47static int led_pwm_set(struct led_classdev *led_cdev,
48 enum led_brightness brightness)
49{
50 struct led_pwm_data *led_dat =
51 container_of(led_cdev, struct led_pwm_data, cdev);
52 unsigned int max = led_dat->cdev.max_brightness;
53 unsigned long long duty = led_dat->period;
54
55 duty *= brightness;
56 do_div(duty, max);
57
58 if (led_dat->active_low)
59 duty = led_dat->period - duty;
60
61 led_dat->duty = duty;
62
63 __led_pwm_set(led_dat);
64
65 return 0;
66}
67
68static inline size_t sizeof_pwm_leds_priv(int num_leds)
69{
70 return sizeof(struct led_pwm_priv) +
71 (sizeof(struct led_pwm_data) * num_leds);
72}
73
74static int led_pwm_add(struct device *dev, struct led_pwm_priv *priv,
75 struct led_pwm *led, struct fwnode_handle *fwnode)
76{
77 struct led_pwm_data *led_data = &priv->leds[priv->num_leds];
78 struct pwm_args pargs;
79 int ret;
80
81 led_data->active_low = led->active_low;
82 led_data->cdev.name = led->name;
83 led_data->cdev.default_trigger = led->default_trigger;
84 led_data->cdev.brightness = LED_OFF;
85 led_data->cdev.max_brightness = led->max_brightness;
86 led_data->cdev.flags = LED_CORE_SUSPENDRESUME;
87
88 if (fwnode)
89 led_data->pwm = devm_fwnode_pwm_get(dev, fwnode, NULL);
90 else
91 led_data->pwm = devm_pwm_get(dev, led->name);
92 if (IS_ERR(led_data->pwm)) {
93 ret = PTR_ERR(led_data->pwm);
94 if (ret != -EPROBE_DEFER)
95 dev_err(dev, "unable to request PWM for %s: %d\n",
96 led->name, ret);
97 return ret;
98 }
99
100 led_data->cdev.brightness_set_blocking = led_pwm_set;
101
102 /*
103 * FIXME: pwm_apply_args() should be removed when switching to the
104 * atomic PWM API.
105 */
106 pwm_apply_args(led_data->pwm);
107
108 pwm_get_args(led_data->pwm, &pargs);
109
110 led_data->period = pargs.period;
111 if (!led_data->period && (led->pwm_period_ns > 0))
112 led_data->period = led->pwm_period_ns;
113
114 ret = devm_of_led_classdev_register(dev, to_of_node(fwnode),
115 &led_data->cdev);
116 if (ret == 0) {
117 priv->num_leds++;
118 led_pwm_set(&led_data->cdev, led_data->cdev.brightness);
119 } else {
120 dev_err(dev, "failed to register PWM led for %s: %d\n",
121 led->name, ret);
122 }
123
124 return ret;
125}
126
127static int led_pwm_create_fwnode(struct device *dev, struct led_pwm_priv *priv)
128{
129 struct fwnode_handle *fwnode;
130 struct led_pwm led;
131 int ret = 0;
132
133 memset(&led, 0, sizeof(led));
134
135 device_for_each_child_node(dev, fwnode) {
136 ret = fwnode_property_read_string(fwnode, "label", &led.name);
137 if (ret && is_of_node(fwnode))
138 led.name = to_of_node(fwnode)->name;
139
140 if (!led.name) {
141 fwnode_handle_put(fwnode);
142 return -EINVAL;
143 }
144
145 fwnode_property_read_string(fwnode, "linux,default-trigger",
146 &led.default_trigger);
147
148 led.active_low = fwnode_property_read_bool(fwnode,
149 "active-low");
150 fwnode_property_read_u32(fwnode, "max-brightness",
151 &led.max_brightness);
152
153 ret = led_pwm_add(dev, priv, &led, fwnode);
154 if (ret) {
155 fwnode_handle_put(fwnode);
156 break;
157 }
158 }
159
160 return ret;
161}
162
163static int led_pwm_probe(struct platform_device *pdev)
164{
165 struct led_pwm_platform_data *pdata = dev_get_platdata(&pdev->dev);
166 struct led_pwm_priv *priv;
167 int count, i;
168 int ret = 0;
169
170 if (pdata)
171 count = pdata->num_leds;
172 else
173 count = device_get_child_node_count(&pdev->dev);
174
175 if (!count)
176 return -EINVAL;
177
178 priv = devm_kzalloc(&pdev->dev, sizeof_pwm_leds_priv(count),
179 GFP_KERNEL);
180 if (!priv)
181 return -ENOMEM;
182
183 if (pdata) {
184 for (i = 0; i < count; i++) {
185 ret = led_pwm_add(&pdev->dev, priv, &pdata->leds[i],
186 NULL);
187 if (ret)
188 break;
189 }
190 } else {
191 ret = led_pwm_create_fwnode(&pdev->dev, priv);
192 }
193
194 if (ret)
195 return ret;
196
197 platform_set_drvdata(pdev, priv);
198
199 return 0;
200}
201
202static const struct of_device_id of_pwm_leds_match[] = {
203 { .compatible = "pwm-leds", },
204 {},
205};
206MODULE_DEVICE_TABLE(of, of_pwm_leds_match);
207
208static struct platform_driver led_pwm_driver = {
209 .probe = led_pwm_probe,
210 .driver = {
211 .name = "leds_pwm",
212 .of_match_table = of_pwm_leds_match,
213 },
214};
215
216module_platform_driver(led_pwm_driver);
217
218MODULE_AUTHOR("Luotao Fu <l.fu@pengutronix.de>");
219MODULE_DESCRIPTION("generic PWM LED driver");
220MODULE_LICENSE("GPL v2");
221MODULE_ALIAS("platform:leds-pwm");