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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/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 #include <linux/workqueue.h>
 26 
 27 struct led_pwm_data {
 28         struct led_classdev     cdev;
 29         struct pwm_device       *pwm;
 30         struct work_struct      work;
 31         unsigned int            active_low;
 32         unsigned int            period;
 33         int                     duty;
 34         bool                    can_sleep;
 35 };
 36 
 37 struct led_pwm_priv {
 38         int num_leds;
 39         struct led_pwm_data leds[0];
 40 };
 41 
 42 static void __led_pwm_set(struct led_pwm_data *led_dat)
 43 {
 44         int new_duty = led_dat->duty;
 45 
 46         pwm_config(led_dat->pwm, new_duty, led_dat->period);
 47 
 48         if (new_duty == 0)
 49                 pwm_disable(led_dat->pwm);
 50         else
 51                 pwm_enable(led_dat->pwm);
 52 }
 53 
 54 static void led_pwm_work(struct work_struct *work)
 55 {
 56         struct led_pwm_data *led_dat =
 57                 container_of(work, struct led_pwm_data, work);
 58 
 59         __led_pwm_set(led_dat);
 60 }
 61 
 62 static void led_pwm_set(struct led_classdev *led_cdev,
 63         enum led_brightness brightness)
 64 {
 65         struct led_pwm_data *led_dat =
 66                 container_of(led_cdev, struct led_pwm_data, cdev);
 67         unsigned int max = led_dat->cdev.max_brightness;
 68         unsigned long long duty =  led_dat->period;
 69 
 70         duty *= brightness;
 71         do_div(duty, max);
 72         led_dat->duty = duty;
 73 
 74         if (led_dat->can_sleep)
 75                 schedule_work(&led_dat->work);
 76         else
 77                 __led_pwm_set(led_dat);
 78 }
 79 
 80 static inline size_t sizeof_pwm_leds_priv(int num_leds)
 81 {
 82         return sizeof(struct led_pwm_priv) +
 83                       (sizeof(struct led_pwm_data) * num_leds);
 84 }
 85 
 86 static void led_pwm_cleanup(struct led_pwm_priv *priv)
 87 {
 88         while (priv->num_leds--) {
 89                 led_classdev_unregister(&priv->leds[priv->num_leds].cdev);
 90                 if (priv->leds[priv->num_leds].can_sleep)
 91                         cancel_work_sync(&priv->leds[priv->num_leds].work);
 92         }
 93 }
 94 
 95 static int led_pwm_create_of(struct platform_device *pdev,
 96                              struct led_pwm_priv *priv)
 97 {
 98         struct device_node *child;
 99         int ret;
100 
101         for_each_child_of_node(pdev->dev.of_node, child) {
102                 struct led_pwm_data *led_dat = &priv->leds[priv->num_leds];
103 
104                 led_dat->cdev.name = of_get_property(child, "label",
105                                                      NULL) ? : child->name;
106 
107                 led_dat->pwm = devm_of_pwm_get(&pdev->dev, child, NULL);
108                 if (IS_ERR(led_dat->pwm)) {
109                         dev_err(&pdev->dev, "unable to request PWM for %s\n",
110                                 led_dat->cdev.name);
111                         ret = PTR_ERR(led_dat->pwm);
112                         goto err;
113                 }
114                 /* Get the period from PWM core when n*/
115                 led_dat->period = pwm_get_period(led_dat->pwm);
116 
117                 led_dat->cdev.default_trigger = of_get_property(child,
118                                                 "linux,default-trigger", NULL);
119                 of_property_read_u32(child, "max-brightness",
120                                      &led_dat->cdev.max_brightness);
121 
122                 led_dat->cdev.brightness_set = led_pwm_set;
123                 led_dat->cdev.brightness = LED_OFF;
124                 led_dat->cdev.flags |= LED_CORE_SUSPENDRESUME;
125 
126                 led_dat->can_sleep = pwm_can_sleep(led_dat->pwm);
127                 if (led_dat->can_sleep)
128                         INIT_WORK(&led_dat->work, led_pwm_work);
129 
130                 ret = led_classdev_register(&pdev->dev, &led_dat->cdev);
131                 if (ret < 0) {
132                         dev_err(&pdev->dev, "failed to register for %s\n",
133                                 led_dat->cdev.name);
134                         of_node_put(child);
135                         goto err;
136                 }
137                 priv->num_leds++;
138         }
139 
140         return 0;
141 err:
142         led_pwm_cleanup(priv);
143 
144         return ret;
145 }
146 
147 static int led_pwm_probe(struct platform_device *pdev)
148 {
149         struct led_pwm_platform_data *pdata = dev_get_platdata(&pdev->dev);
150         struct led_pwm_priv *priv;
151         int count, i;
152         int ret = 0;
153 
154         if (pdata)
155                 count = pdata->num_leds;
156         else
157                 count = of_get_child_count(pdev->dev.of_node);
158 
159         if (!count)
160                 return -EINVAL;
161 
162         priv = devm_kzalloc(&pdev->dev, sizeof_pwm_leds_priv(count),
163                             GFP_KERNEL);
164         if (!priv)
165                 return -ENOMEM;
166 
167         if (pdata) {
168                 for (i = 0; i < count; i++) {
169                         struct led_pwm *cur_led = &pdata->leds[i];
170                         struct led_pwm_data *led_dat = &priv->leds[i];
171 
172                         led_dat->pwm = devm_pwm_get(&pdev->dev, cur_led->name);
173                         if (IS_ERR(led_dat->pwm)) {
174                                 ret = PTR_ERR(led_dat->pwm);
175                                 dev_err(&pdev->dev,
176                                         "unable to request PWM for %s\n",
177                                         cur_led->name);
178                                 goto err;
179                         }
180 
181                         led_dat->cdev.name = cur_led->name;
182                         led_dat->cdev.default_trigger = cur_led->default_trigger;
183                         led_dat->active_low = cur_led->active_low;
184                         led_dat->period = cur_led->pwm_period_ns;
185                         led_dat->cdev.brightness_set = led_pwm_set;
186                         led_dat->cdev.brightness = LED_OFF;
187                         led_dat->cdev.max_brightness = cur_led->max_brightness;
188                         led_dat->cdev.flags |= LED_CORE_SUSPENDRESUME;
189 
190                         led_dat->can_sleep = pwm_can_sleep(led_dat->pwm);
191                         if (led_dat->can_sleep)
192                                 INIT_WORK(&led_dat->work, led_pwm_work);
193 
194                         ret = led_classdev_register(&pdev->dev, &led_dat->cdev);
195                         if (ret < 0)
196                                 goto err;
197                 }
198                 priv->num_leds = count;
199         } else {
200                 ret = led_pwm_create_of(pdev, priv);
201                 if (ret)
202                         return ret;
203         }
204 
205         platform_set_drvdata(pdev, priv);
206 
207         return 0;
208 
209 err:
210         priv->num_leds = i;
211         led_pwm_cleanup(priv);
212 
213         return ret;
214 }
215 
216 static int led_pwm_remove(struct platform_device *pdev)
217 {
218         struct led_pwm_priv *priv = platform_get_drvdata(pdev);
219 
220         led_pwm_cleanup(priv);
221 
222         return 0;
223 }
224 
225 static const struct of_device_id of_pwm_leds_match[] = {
226         { .compatible = "pwm-leds", },
227         {},
228 };
229 MODULE_DEVICE_TABLE(of, of_pwm_leds_match);
230 
231 static struct platform_driver led_pwm_driver = {
232         .probe          = led_pwm_probe,
233         .remove         = led_pwm_remove,
234         .driver         = {
235                 .name   = "leds_pwm",
236                 .owner  = THIS_MODULE,
237                 .of_match_table = of_pwm_leds_match,
238         },
239 };
240 
241 module_platform_driver(led_pwm_driver);
242 
243 MODULE_AUTHOR("Luotao Fu <l.fu@pengutronix.de>");
244 MODULE_DESCRIPTION("PWM LED driver for PXA");
245 MODULE_LICENSE("GPL");
246 MODULE_ALIAS("platform:leds-pwm");
247 

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