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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#include "leds.h"
21
22struct led_pwm {
23 const char *name;
24 u8 active_low;
25 u8 default_state;
26 unsigned int max_brightness;
27};
28
29struct led_pwm_data {
30 struct led_classdev cdev;
31 struct pwm_device *pwm;
32 struct pwm_state pwmstate;
33 unsigned int active_low;
34};
35
36struct led_pwm_priv {
37 int num_leds;
38 struct led_pwm_data leds[];
39};
40
41static int led_pwm_set(struct led_classdev *led_cdev,
42 enum led_brightness brightness)
43{
44 struct led_pwm_data *led_dat =
45 container_of(led_cdev, struct led_pwm_data, cdev);
46 unsigned int max = led_dat->cdev.max_brightness;
47 unsigned long long duty = led_dat->pwmstate.period;
48
49 duty *= brightness;
50 do_div(duty, max);
51
52 if (led_dat->active_low)
53 duty = led_dat->pwmstate.period - duty;
54
55 led_dat->pwmstate.duty_cycle = duty;
56 led_dat->pwmstate.enabled = duty > 0;
57 return pwm_apply_state(led_dat->pwm, &led_dat->pwmstate);
58}
59
60__attribute__((nonnull))
61static int led_pwm_add(struct device *dev, struct led_pwm_priv *priv,
62 struct led_pwm *led, struct fwnode_handle *fwnode)
63{
64 struct led_pwm_data *led_data = &priv->leds[priv->num_leds];
65 struct led_init_data init_data = { .fwnode = fwnode };
66 int ret;
67
68 led_data->active_low = led->active_low;
69 led_data->cdev.name = led->name;
70 led_data->cdev.brightness = LED_OFF;
71 led_data->cdev.max_brightness = led->max_brightness;
72 led_data->cdev.flags = LED_CORE_SUSPENDRESUME;
73
74 led_data->pwm = devm_fwnode_pwm_get(dev, fwnode, NULL);
75 if (IS_ERR(led_data->pwm))
76 return dev_err_probe(dev, PTR_ERR(led_data->pwm),
77 "unable to request PWM for %s\n",
78 led->name);
79
80 led_data->cdev.brightness_set_blocking = led_pwm_set;
81
82
83 switch (led->default_state) {
84 case LEDS_DEFSTATE_KEEP:
85 pwm_get_state(led_data->pwm, &led_data->pwmstate);
86 if (led_data->pwmstate.period)
87 break;
88 led->default_state = LEDS_DEFSTATE_OFF;
89 dev_warn(dev,
90 "failed to read period for %s, default to off",
91 led->name);
92 fallthrough;
93 default:
94 pwm_init_state(led_data->pwm, &led_data->pwmstate);
95 break;
96 }
97
98
99 switch (led->default_state) {
100 case LEDS_DEFSTATE_ON:
101 led_data->cdev.brightness = led->max_brightness;
102 break;
103 case LEDS_DEFSTATE_KEEP:
104 {
105 uint64_t brightness;
106
107 brightness = led->max_brightness;
108 brightness *= led_data->pwmstate.duty_cycle;
109 do_div(brightness, led_data->pwmstate.period);
110 led_data->cdev.brightness = brightness;
111 }
112 break;
113 }
114
115 ret = devm_led_classdev_register_ext(dev, &led_data->cdev, &init_data);
116 if (ret) {
117 dev_err(dev, "failed to register PWM led for %s: %d\n",
118 led->name, ret);
119 return ret;
120 }
121
122 if (led->default_state != LEDS_DEFSTATE_KEEP) {
123 ret = led_pwm_set(&led_data->cdev, led_data->cdev.brightness);
124 if (ret) {
125 dev_err(dev, "failed to set led PWM value for %s: %d",
126 led->name, ret);
127 return ret;
128 }
129 }
130
131 priv->num_leds++;
132 return 0;
133}
134
135static int led_pwm_create_fwnode(struct device *dev, struct led_pwm_priv *priv)
136{
137 struct fwnode_handle *fwnode;
138 struct led_pwm led;
139 int ret;
140
141 memset(&led, 0, sizeof(led));
142
143 device_for_each_child_node(dev, fwnode) {
144 ret = fwnode_property_read_string(fwnode, "label", &led.name);
145 if (ret && is_of_node(fwnode))
146 led.name = to_of_node(fwnode)->name;
147
148 if (!led.name) {
149 ret = EINVAL;
150 goto err_child_out;
151 }
152
153 led.active_low = fwnode_property_read_bool(fwnode,
154 "active-low");
155 fwnode_property_read_u32(fwnode, "max-brightness",
156 &led.max_brightness);
157
158 led.default_state = led_init_default_state_get(fwnode);
159
160 ret = led_pwm_add(dev, priv, &led, fwnode);
161 if (ret)
162 goto err_child_out;
163 }
164
165 return 0;
166
167err_child_out:
168 fwnode_handle_put(fwnode);
169 return ret;
170}
171
172static int led_pwm_probe(struct platform_device *pdev)
173{
174 struct led_pwm_priv *priv;
175 int ret = 0;
176 int count;
177
178 count = device_get_child_node_count(&pdev->dev);
179
180 if (!count)
181 return -EINVAL;
182
183 priv = devm_kzalloc(&pdev->dev, struct_size(priv, leds, count),
184 GFP_KERNEL);
185 if (!priv)
186 return -ENOMEM;
187
188 ret = led_pwm_create_fwnode(&pdev->dev, priv);
189
190 if (ret)
191 return ret;
192
193 platform_set_drvdata(pdev, priv);
194
195 return 0;
196}
197
198static const struct of_device_id of_pwm_leds_match[] = {
199 { .compatible = "pwm-leds", },
200 {},
201};
202MODULE_DEVICE_TABLE(of, of_pwm_leds_match);
203
204static struct platform_driver led_pwm_driver = {
205 .probe = led_pwm_probe,
206 .driver = {
207 .name = "leds_pwm",
208 .of_match_table = of_pwm_leds_match,
209 },
210};
211
212module_platform_driver(led_pwm_driver);
213
214MODULE_AUTHOR("Luotao Fu <l.fu@pengutronix.de>");
215MODULE_DESCRIPTION("generic PWM LED driver");
216MODULE_LICENSE("GPL v2");
217MODULE_ALIAS("platform:leds-pwm");
218
