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Linux/drivers/leds/leds-pwm.c

  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/init.h>
 18 #include <linux/platform_device.h>
 19 #include <linux/of_platform.h>
 20 #include <linux/fb.h>
 21 #include <linux/leds.h>
 22 #include <linux/err.h>
 23 #include <linux/pwm.h>
 24 #include <linux/leds_pwm.h>
 25 #include <linux/slab.h>
 26 #include <linux/workqueue.h>
 27 
 28 struct led_pwm_data {
 29         struct led_classdev     cdev;
 30         struct pwm_device       *pwm;
 31         struct work_struct      work;
 32         unsigned int            active_low;
 33         unsigned int            period;
 34         int                     duty;
 35         bool                    can_sleep;
 36 };
 37 
 38 struct led_pwm_priv {
 39         int num_leds;
 40         struct led_pwm_data leds[0];
 41 };
 42 
 43 static void __led_pwm_set(struct led_pwm_data *led_dat)
 44 {
 45         int new_duty = led_dat->duty;
 46 
 47         pwm_config(led_dat->pwm, new_duty, led_dat->period);
 48 
 49         if (new_duty == 0)
 50                 pwm_disable(led_dat->pwm);
 51         else
 52                 pwm_enable(led_dat->pwm);
 53 }
 54 
 55 static void led_pwm_work(struct work_struct *work)
 56 {
 57         struct led_pwm_data *led_dat =
 58                 container_of(work, struct led_pwm_data, work);
 59 
 60         __led_pwm_set(led_dat);
 61 }
 62 
 63 static void led_pwm_set(struct led_classdev *led_cdev,
 64         enum led_brightness brightness)
 65 {
 66         struct led_pwm_data *led_dat =
 67                 container_of(led_cdev, struct led_pwm_data, cdev);
 68         unsigned int max = led_dat->cdev.max_brightness;
 69         unsigned long long duty =  led_dat->period;
 70 
 71         duty *= brightness;
 72         do_div(duty, max);
 73         led_dat->duty = duty;
 74 
 75         if (led_dat->can_sleep)
 76                 schedule_work(&led_dat->work);
 77         else
 78                 __led_pwm_set(led_dat);
 79 }
 80 
 81 static inline size_t sizeof_pwm_leds_priv(int num_leds)
 82 {
 83         return sizeof(struct led_pwm_priv) +
 84                       (sizeof(struct led_pwm_data) * num_leds);
 85 }
 86 
 87 static int led_pwm_create_of(struct platform_device *pdev,
 88                              struct led_pwm_priv *priv)
 89 {
 90         struct device_node *child;
 91         int ret;
 92 
 93         for_each_child_of_node(pdev->dev.of_node, child) {
 94                 struct led_pwm_data *led_dat = &priv->leds[priv->num_leds];
 95 
 96                 led_dat->cdev.name = of_get_property(child, "label",
 97                                                      NULL) ? : child->name;
 98 
 99                 led_dat->pwm = devm_of_pwm_get(&pdev->dev, child, NULL);
100                 if (IS_ERR(led_dat->pwm)) {
101                         dev_err(&pdev->dev, "unable to request PWM for %s\n",
102                                 led_dat->cdev.name);
103                         ret = PTR_ERR(led_dat->pwm);
104                         goto err;
105                 }
106                 /* Get the period from PWM core when n*/
107                 led_dat->period = pwm_get_period(led_dat->pwm);
108 
109                 led_dat->cdev.default_trigger = of_get_property(child,
110                                                 "linux,default-trigger", NULL);
111                 of_property_read_u32(child, "max-brightness",
112                                      &led_dat->cdev.max_brightness);
113 
114                 led_dat->cdev.brightness_set = led_pwm_set;
115                 led_dat->cdev.brightness = LED_OFF;
116                 led_dat->cdev.flags |= LED_CORE_SUSPENDRESUME;
117 
118                 led_dat->can_sleep = pwm_can_sleep(led_dat->pwm);
119                 if (led_dat->can_sleep)
120                         INIT_WORK(&led_dat->work, led_pwm_work);
121 
122                 ret = led_classdev_register(&pdev->dev, &led_dat->cdev);
123                 if (ret < 0) {
124                         dev_err(&pdev->dev, "failed to register for %s\n",
125                                 led_dat->cdev.name);
126                         of_node_put(child);
127                         goto err;
128                 }
129                 priv->num_leds++;
130         }
131 
132         return 0;
133 err:
134         while (priv->num_leds--)
135                 led_classdev_unregister(&priv->leds[priv->num_leds].cdev);
136 
137         return ret;
138 }
139 
140 static int led_pwm_probe(struct platform_device *pdev)
141 {
142         struct led_pwm_platform_data *pdata = dev_get_platdata(&pdev->dev);
143         struct led_pwm_priv *priv;
144         int count, i;
145         int ret = 0;
146 
147         if (pdata)
148                 count = pdata->num_leds;
149         else
150                 count = of_get_child_count(pdev->dev.of_node);
151 
152         if (!count)
153                 return -EINVAL;
154 
155         priv = devm_kzalloc(&pdev->dev, sizeof_pwm_leds_priv(count),
156                             GFP_KERNEL);
157         if (!priv)
158                 return -ENOMEM;
159 
160         if (pdata) {
161                 for (i = 0; i < count; i++) {
162                         struct led_pwm *cur_led = &pdata->leds[i];
163                         struct led_pwm_data *led_dat = &priv->leds[i];
164 
165                         led_dat->pwm = devm_pwm_get(&pdev->dev, cur_led->name);
166                         if (IS_ERR(led_dat->pwm)) {
167                                 ret = PTR_ERR(led_dat->pwm);
168                                 dev_err(&pdev->dev,
169                                         "unable to request PWM for %s\n",
170                                         cur_led->name);
171                                 goto err;
172                         }
173 
174                         led_dat->cdev.name = cur_led->name;
175                         led_dat->cdev.default_trigger = cur_led->default_trigger;
176                         led_dat->active_low = cur_led->active_low;
177                         led_dat->period = cur_led->pwm_period_ns;
178                         led_dat->cdev.brightness_set = led_pwm_set;
179                         led_dat->cdev.brightness = LED_OFF;
180                         led_dat->cdev.max_brightness = cur_led->max_brightness;
181                         led_dat->cdev.flags |= LED_CORE_SUSPENDRESUME;
182 
183                         led_dat->can_sleep = pwm_can_sleep(led_dat->pwm);
184                         if (led_dat->can_sleep)
185                                 INIT_WORK(&led_dat->work, led_pwm_work);
186 
187                         ret = led_classdev_register(&pdev->dev, &led_dat->cdev);
188                         if (ret < 0)
189                                 goto err;
190                 }
191                 priv->num_leds = count;
192         } else {
193                 ret = led_pwm_create_of(pdev, priv);
194                 if (ret)
195                         return ret;
196         }
197 
198         platform_set_drvdata(pdev, priv);
199 
200         return 0;
201 
202 err:
203         while (i--)
204                 led_classdev_unregister(&priv->leds[i].cdev);
205 
206         return ret;
207 }
208 
209 static int led_pwm_remove(struct platform_device *pdev)
210 {
211         struct led_pwm_priv *priv = platform_get_drvdata(pdev);
212         int i;
213 
214         for (i = 0; i < priv->num_leds; i++) {
215                 led_classdev_unregister(&priv->leds[i].cdev);
216                 if (priv->leds[i].can_sleep)
217                         cancel_work_sync(&priv->leds[i].work);
218         }
219 
220         return 0;
221 }
222 
223 static const struct of_device_id of_pwm_leds_match[] = {
224         { .compatible = "pwm-leds", },
225         {},
226 };
227 MODULE_DEVICE_TABLE(of, of_pwm_leds_match);
228 
229 static struct platform_driver led_pwm_driver = {
230         .probe          = led_pwm_probe,
231         .remove         = led_pwm_remove,
232         .driver         = {
233                 .name   = "leds_pwm",
234                 .owner  = THIS_MODULE,
235                 .of_match_table = of_pwm_leds_match,
236         },
237 };
238 
239 module_platform_driver(led_pwm_driver);
240 
241 MODULE_AUTHOR("Luotao Fu <l.fu@pengutronix.de>");
242 MODULE_DESCRIPTION("PWM LED driver for PXA");
243 MODULE_LICENSE("GPL");
244 MODULE_ALIAS("platform:leds-pwm");
245 

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