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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.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 u8 default_state;
25 unsigned int max_brightness;
26};
27
28struct led_pwm_data {
29 struct led_classdev cdev;
30 struct pwm_device *pwm;
31 struct pwm_state pwmstate;
32 unsigned int active_low;
33};
34
35struct led_pwm_priv {
36 int num_leds;
37 struct led_pwm_data leds[];
38};
39
40static int led_pwm_set(struct led_classdev *led_cdev,
41 enum led_brightness brightness)
42{
43 struct led_pwm_data *led_dat =
44 container_of(led_cdev, struct led_pwm_data, cdev);
45 unsigned int max = led_dat->cdev.max_brightness;
46 unsigned long long duty = led_dat->pwmstate.period;
47
48 duty *= brightness;
49 do_div(duty, max);
50
51 if (led_dat->active_low)
52 duty = led_dat->pwmstate.period - duty;
53
54 led_dat->pwmstate.duty_cycle = duty;
55 /*
56 * Disabling a PWM doesn't guarantee that it emits the inactive level.
57 * So keep it on. Only for suspending the PWM should be disabled because
58 * otherwise it refuses to suspend. The possible downside is that the
59 * LED might stay (or even go) on.
60 */
61 led_dat->pwmstate.enabled = !(led_cdev->flags & LED_SUSPENDED);
62 return pwm_apply_might_sleep(led_dat->pwm, &led_dat->pwmstate);
63}
64
65static int led_pwm_default_brightness_get(struct fwnode_handle *fwnode,
66 int max_brightness)
67{
68 unsigned int default_brightness;
69 int ret;
70
71 ret = fwnode_property_read_u32(fwnode, "default-brightness",
72 &default_brightness);
73 if (ret < 0 || default_brightness > max_brightness)
74 default_brightness = max_brightness;
75
76 return default_brightness;
77}
78
79__attribute__((nonnull))
80static int led_pwm_add(struct device *dev, struct led_pwm_priv *priv,
81 struct led_pwm *led, struct fwnode_handle *fwnode)
82{
83 struct led_pwm_data *led_data = &priv->leds[priv->num_leds];
84 struct led_init_data init_data = { .fwnode = fwnode };
85 int ret;
86
87 led_data->active_low = led->active_low;
88 led_data->cdev.name = led->name;
89 led_data->cdev.brightness = LED_OFF;
90 led_data->cdev.max_brightness = led->max_brightness;
91 led_data->cdev.flags = LED_CORE_SUSPENDRESUME;
92
93 led_data->pwm = devm_fwnode_pwm_get(dev, fwnode, NULL);
94 if (IS_ERR(led_data->pwm))
95 return dev_err_probe(dev, PTR_ERR(led_data->pwm),
96 "unable to request PWM for %s\n",
97 led->name);
98
99 led_data->cdev.brightness_set_blocking = led_pwm_set;
100
101 /* init PWM state */
102 switch (led->default_state) {
103 case LEDS_DEFSTATE_KEEP:
104 pwm_get_state(led_data->pwm, &led_data->pwmstate);
105 if (led_data->pwmstate.period)
106 break;
107 led->default_state = LEDS_DEFSTATE_OFF;
108 dev_warn(dev,
109 "failed to read period for %s, default to off",
110 led->name);
111 fallthrough;
112 default:
113 pwm_init_state(led_data->pwm, &led_data->pwmstate);
114 break;
115 }
116
117 /* set brightness */
118 switch (led->default_state) {
119 case LEDS_DEFSTATE_ON:
120 led_data->cdev.brightness =
121 led_pwm_default_brightness_get(fwnode, led->max_brightness);
122 break;
123 case LEDS_DEFSTATE_KEEP:
124 {
125 uint64_t brightness;
126
127 brightness = led->max_brightness;
128 brightness *= led_data->pwmstate.duty_cycle;
129 do_div(brightness, led_data->pwmstate.period);
130 led_data->cdev.brightness = brightness;
131 }
132 break;
133 }
134
135 ret = devm_led_classdev_register_ext(dev, &led_data->cdev, &init_data);
136 if (ret) {
137 dev_err(dev, "failed to register PWM led for %s: %d\n",
138 led->name, ret);
139 return ret;
140 }
141
142 if (led->default_state != LEDS_DEFSTATE_KEEP) {
143 ret = led_pwm_set(&led_data->cdev, led_data->cdev.brightness);
144 if (ret) {
145 dev_err(dev, "failed to set led PWM value for %s: %d",
146 led->name, ret);
147 return ret;
148 }
149 }
150
151 priv->num_leds++;
152 return 0;
153}
154
155static int led_pwm_create_fwnode(struct device *dev, struct led_pwm_priv *priv)
156{
157 struct led_pwm led;
158 int ret;
159
160 device_for_each_child_node_scoped(dev, fwnode) {
161 memset(&led, 0, sizeof(led));
162
163 ret = fwnode_property_read_string(fwnode, "label", &led.name);
164 if (ret && is_of_node(fwnode))
165 led.name = to_of_node(fwnode)->name;
166
167 if (!led.name)
168 return -EINVAL;
169
170 led.active_low = fwnode_property_read_bool(fwnode,
171 "active-low");
172 fwnode_property_read_u32(fwnode, "max-brightness",
173 &led.max_brightness);
174
175 led.default_state = led_init_default_state_get(fwnode);
176
177 ret = led_pwm_add(dev, priv, &led, fwnode);
178 if (ret)
179 return ret;
180 }
181
182 return 0;
183}
184
185static int led_pwm_probe(struct platform_device *pdev)
186{
187 struct led_pwm_priv *priv;
188 int ret = 0;
189 int count;
190
191 count = device_get_child_node_count(&pdev->dev);
192
193 if (!count)
194 return -EINVAL;
195
196 priv = devm_kzalloc(&pdev->dev, struct_size(priv, leds, count),
197 GFP_KERNEL);
198 if (!priv)
199 return -ENOMEM;
200
201 ret = led_pwm_create_fwnode(&pdev->dev, priv);
202
203 if (ret)
204 return ret;
205
206 platform_set_drvdata(pdev, priv);
207
208 return 0;
209}
210
211static const struct of_device_id of_pwm_leds_match[] = {
212 { .compatible = "pwm-leds", },
213 {},
214};
215MODULE_DEVICE_TABLE(of, of_pwm_leds_match);
216
217static struct platform_driver led_pwm_driver = {
218 .probe = led_pwm_probe,
219 .driver = {
220 .name = "leds_pwm",
221 .of_match_table = of_pwm_leds_match,
222 },
223};
224
225module_platform_driver(led_pwm_driver);
226
227MODULE_AUTHOR("Luotao Fu <l.fu@pengutronix.de>");
228MODULE_DESCRIPTION("generic PWM LED driver");
229MODULE_LICENSE("GPL v2");
230MODULE_ALIAS("platform:leds-pwm");
1/*
2 * linux/drivers/leds-pwm.c
3 *
4 * simple PWM based LED control
5 *
6 * Copyright 2009 Luotao Fu @ Pengutronix (l.fu@pengutronix.de)
7 *
8 * based on leds-gpio.c by Raphael Assenat <raph@8d.com>
9 *
10 * This program is free software; you can redistribute it and/or modify
11 * it under the terms of the GNU General Public License version 2 as
12 * published by the Free Software Foundation.
13 */
14
15#include <linux/module.h>
16#include <linux/kernel.h>
17#include <linux/platform_device.h>
18#include <linux/of_platform.h>
19#include <linux/fb.h>
20#include <linux/leds.h>
21#include <linux/err.h>
22#include <linux/pwm.h>
23#include <linux/leds_pwm.h>
24#include <linux/slab.h>
25
26struct led_pwm_data {
27 struct led_classdev cdev;
28 struct pwm_device *pwm;
29 unsigned int active_low;
30 unsigned int period;
31 int duty;
32 bool can_sleep;
33};
34
35struct led_pwm_priv {
36 int num_leds;
37 struct led_pwm_data leds[0];
38};
39
40static void __led_pwm_set(struct led_pwm_data *led_dat)
41{
42 int new_duty = led_dat->duty;
43
44 pwm_config(led_dat->pwm, new_duty, led_dat->period);
45
46 if (new_duty == 0)
47 pwm_disable(led_dat->pwm);
48 else
49 pwm_enable(led_dat->pwm);
50}
51
52static void led_pwm_set(struct led_classdev *led_cdev,
53 enum led_brightness brightness)
54{
55 struct led_pwm_data *led_dat =
56 container_of(led_cdev, struct led_pwm_data, cdev);
57 unsigned int max = led_dat->cdev.max_brightness;
58 unsigned long long duty = led_dat->period;
59
60 duty *= brightness;
61 do_div(duty, max);
62
63 if (led_dat->active_low)
64 duty = led_dat->period - duty;
65
66 led_dat->duty = duty;
67
68 __led_pwm_set(led_dat);
69}
70
71static int led_pwm_set_blocking(struct led_classdev *led_cdev,
72 enum led_brightness brightness)
73{
74 led_pwm_set(led_cdev, brightness);
75 return 0;
76}
77
78static inline size_t sizeof_pwm_leds_priv(int num_leds)
79{
80 return sizeof(struct led_pwm_priv) +
81 (sizeof(struct led_pwm_data) * num_leds);
82}
83
84static void led_pwm_cleanup(struct led_pwm_priv *priv)
85{
86 while (priv->num_leds--)
87 led_classdev_unregister(&priv->leds[priv->num_leds].cdev);
88}
89
90static int led_pwm_add(struct device *dev, struct led_pwm_priv *priv,
91 struct led_pwm *led, struct device_node *child)
92{
93 struct led_pwm_data *led_data = &priv->leds[priv->num_leds];
94 struct pwm_args pargs;
95 int ret;
96
97 led_data->active_low = led->active_low;
98 led_data->cdev.name = led->name;
99 led_data->cdev.default_trigger = led->default_trigger;
100 led_data->cdev.brightness = LED_OFF;
101 led_data->cdev.max_brightness = led->max_brightness;
102 led_data->cdev.flags = LED_CORE_SUSPENDRESUME;
103
104 if (child)
105 led_data->pwm = devm_of_pwm_get(dev, child, NULL);
106 else
107 led_data->pwm = devm_pwm_get(dev, led->name);
108 if (IS_ERR(led_data->pwm)) {
109 ret = PTR_ERR(led_data->pwm);
110 dev_err(dev, "unable to request PWM for %s: %d\n",
111 led->name, ret);
112 return ret;
113 }
114
115 led_data->can_sleep = pwm_can_sleep(led_data->pwm);
116 if (!led_data->can_sleep)
117 led_data->cdev.brightness_set = led_pwm_set;
118 else
119 led_data->cdev.brightness_set_blocking = led_pwm_set_blocking;
120
121 /*
122 * FIXME: pwm_apply_args() should be removed when switching to the
123 * atomic PWM API.
124 */
125 pwm_apply_args(led_data->pwm);
126
127 pwm_get_args(led_data->pwm, &pargs);
128
129 led_data->period = pargs.period;
130 if (!led_data->period && (led->pwm_period_ns > 0))
131 led_data->period = led->pwm_period_ns;
132
133 ret = led_classdev_register(dev, &led_data->cdev);
134 if (ret == 0) {
135 priv->num_leds++;
136 led_pwm_set(&led_data->cdev, led_data->cdev.brightness);
137 } else {
138 dev_err(dev, "failed to register PWM led for %s: %d\n",
139 led->name, ret);
140 }
141
142 return ret;
143}
144
145static int led_pwm_create_of(struct device *dev, struct led_pwm_priv *priv)
146{
147 struct device_node *child;
148 struct led_pwm led;
149 int ret = 0;
150
151 memset(&led, 0, sizeof(led));
152
153 for_each_child_of_node(dev->of_node, child) {
154 led.name = of_get_property(child, "label", NULL) ? :
155 child->name;
156
157 led.default_trigger = of_get_property(child,
158 "linux,default-trigger", NULL);
159 led.active_low = of_property_read_bool(child, "active-low");
160 of_property_read_u32(child, "max-brightness",
161 &led.max_brightness);
162
163 ret = led_pwm_add(dev, priv, &led, child);
164 if (ret) {
165 of_node_put(child);
166 break;
167 }
168 }
169
170 return ret;
171}
172
173static int led_pwm_probe(struct platform_device *pdev)
174{
175 struct led_pwm_platform_data *pdata = dev_get_platdata(&pdev->dev);
176 struct led_pwm_priv *priv;
177 int count, i;
178 int ret = 0;
179
180 if (pdata)
181 count = pdata->num_leds;
182 else
183 count = of_get_child_count(pdev->dev.of_node);
184
185 if (!count)
186 return -EINVAL;
187
188 priv = devm_kzalloc(&pdev->dev, sizeof_pwm_leds_priv(count),
189 GFP_KERNEL);
190 if (!priv)
191 return -ENOMEM;
192
193 if (pdata) {
194 for (i = 0; i < count; i++) {
195 ret = led_pwm_add(&pdev->dev, priv, &pdata->leds[i],
196 NULL);
197 if (ret)
198 break;
199 }
200 } else {
201 ret = led_pwm_create_of(&pdev->dev, priv);
202 }
203
204 if (ret) {
205 led_pwm_cleanup(priv);
206 return ret;
207 }
208
209 platform_set_drvdata(pdev, priv);
210
211 return 0;
212}
213
214static int led_pwm_remove(struct platform_device *pdev)
215{
216 struct led_pwm_priv *priv = platform_get_drvdata(pdev);
217
218 led_pwm_cleanup(priv);
219
220 return 0;
221}
222
223static const struct of_device_id of_pwm_leds_match[] = {
224 { .compatible = "pwm-leds", },
225 {},
226};
227MODULE_DEVICE_TABLE(of, of_pwm_leds_match);
228
229static struct platform_driver led_pwm_driver = {
230 .probe = led_pwm_probe,
231 .remove = led_pwm_remove,
232 .driver = {
233 .name = "leds_pwm",
234 .of_match_table = of_pwm_leds_match,
235 },
236};
237
238module_platform_driver(led_pwm_driver);
239
240MODULE_AUTHOR("Luotao Fu <l.fu@pengutronix.de>");
241MODULE_DESCRIPTION("generic PWM LED driver");
242MODULE_LICENSE("GPL v2");
243MODULE_ALIAS("platform:leds-pwm");