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	u8		active_low;
24	unsigned int	max_brightness;
25};
26
27struct led_pwm_data {
28	struct led_classdev	cdev;
29	struct pwm_device	*pwm;
30	struct pwm_state	pwmstate;
31	unsigned int		active_low;
32};
33
34struct led_pwm_priv {
35	int num_leds;
36	struct led_pwm_data leds[];
37};
38
39static int led_pwm_set(struct led_classdev *led_cdev,
40		       enum led_brightness brightness)
41{
42	struct led_pwm_data *led_dat =
43		container_of(led_cdev, struct led_pwm_data, cdev);
44	unsigned int max = led_dat->cdev.max_brightness;
45	unsigned long long duty = led_dat->pwmstate.period;
46
47	duty *= brightness;
48	do_div(duty, max);
49
50	if (led_dat->active_low)
51		duty = led_dat->pwmstate.period - duty;
52
53	led_dat->pwmstate.duty_cycle = duty;
54	led_dat->pwmstate.enabled = true;
55	return pwm_apply_state(led_dat->pwm, &led_dat->pwmstate);
56}
57
58__attribute__((nonnull))
59static int led_pwm_add(struct device *dev, struct led_pwm_priv *priv,
60		       struct led_pwm *led, struct fwnode_handle *fwnode)
61{
62	struct led_pwm_data *led_data = &priv->leds[priv->num_leds];
63	struct led_init_data init_data = { .fwnode = fwnode };
64	int ret;
65
66	led_data->active_low = led->active_low;
67	led_data->cdev.name = led->name;
68	led_data->cdev.brightness = LED_OFF;
69	led_data->cdev.max_brightness = led->max_brightness;
70	led_data->cdev.flags = LED_CORE_SUSPENDRESUME;
71
72	led_data->pwm = devm_fwnode_pwm_get(dev, fwnode, NULL);
73	if (IS_ERR(led_data->pwm))
74		return dev_err_probe(dev, PTR_ERR(led_data->pwm),
75				     "unable to request PWM for %s\n",
76				     led->name);
77
78	led_data->cdev.brightness_set_blocking = led_pwm_set;
79
80	pwm_init_state(led_data->pwm, &led_data->pwmstate);
81
82	ret = devm_led_classdev_register_ext(dev, &led_data->cdev, &init_data);
83	if (ret) {
84		dev_err(dev, "failed to register PWM led for %s: %d\n",
85			led->name, ret);
86		return ret;
87	}
88
89	ret = led_pwm_set(&led_data->cdev, led_data->cdev.brightness);
90	if (ret) {
91		dev_err(dev, "failed to set led PWM value for %s: %d",
92			led->name, ret);
93		return ret;
94	}
95
96	priv->num_leds++;
97	return 0;
98}
99
100static int led_pwm_create_fwnode(struct device *dev, struct led_pwm_priv *priv)
101{
102	struct fwnode_handle *fwnode;
103	struct led_pwm led;
104	int ret = 0;
105
106	memset(&led, 0, sizeof(led));
107
108	device_for_each_child_node(dev, fwnode) {
109		ret = fwnode_property_read_string(fwnode, "label", &led.name);
110		if (ret && is_of_node(fwnode))
111			led.name = to_of_node(fwnode)->name;
112
113		if (!led.name) {
114			fwnode_handle_put(fwnode);
115			return -EINVAL;
116		}
117
118		led.active_low = fwnode_property_read_bool(fwnode,
119							   "active-low");
120		fwnode_property_read_u32(fwnode, "max-brightness",
121					 &led.max_brightness);
122
123		ret = led_pwm_add(dev, priv, &led, fwnode);
124		if (ret) {
125			fwnode_handle_put(fwnode);
126			break;
127		}
128	}
129
130	return ret;
131}
132
133static int led_pwm_probe(struct platform_device *pdev)
134{
135	struct led_pwm_priv *priv;
136	int ret = 0;
137	int count;
138
139	count = device_get_child_node_count(&pdev->dev);
140
141	if (!count)
142		return -EINVAL;
143
144	priv = devm_kzalloc(&pdev->dev, struct_size(priv, leds, count),
145			    GFP_KERNEL);
146	if (!priv)
147		return -ENOMEM;
148
149	ret = led_pwm_create_fwnode(&pdev->dev, priv);
150
151	if (ret)
152		return ret;
153
154	platform_set_drvdata(pdev, priv);
155
156	return 0;
157}
158
159static const struct of_device_id of_pwm_leds_match[] = {
160	{ .compatible = "pwm-leds", },
161	{},
162};
163MODULE_DEVICE_TABLE(of, of_pwm_leds_match);
164
165static struct platform_driver led_pwm_driver = {
166	.probe		= led_pwm_probe,
167	.driver		= {
168		.name	= "leds_pwm",
169		.of_match_table = of_pwm_leds_match,
170	},
171};
172
173module_platform_driver(led_pwm_driver);
174
175MODULE_AUTHOR("Luotao Fu <l.fu@pengutronix.de>");
176MODULE_DESCRIPTION("generic PWM LED driver");
177MODULE_LICENSE("GPL v2");
178MODULE_ALIAS("platform:leds-pwm");
179