drivers/leds/leds-pwm.c

   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/leds_pwm.h>
  20 #include <linux/slab.h>
  21
  22 struct led_pwm_data {
  23         struct led_classdev     cdev;
  24         struct pwm_device       *pwm;
  25         unsigned int            active_low;
  26         unsigned int            period;
  27         int                     duty;
  28 };
  29
  30 struct led_pwm_priv {
  31         int num_leds;
  32         struct led_pwm_data leds[0];
  33 };
  34
  35 static void __led_pwm_set(struct led_pwm_data *led_dat)
  36 {
  37         int new_duty = led_dat->duty;
  38
  39         pwm_config(led_dat->pwm, new_duty, led_dat->period);
  40
  41         if (new_duty == 0)
  42                 pwm_disable(led_dat->pwm);
  43         else
  44                 pwm_enable(led_dat->pwm);
  45 }
  46
  47 static int led_pwm_set(struct led_classdev *led_cdev,
  48                        enum led_brightness brightness)
  49 {
  50         struct led_pwm_data *led_dat =
  51                 container_of(led_cdev, struct led_pwm_data, cdev);
  52         unsigned int max = led_dat->cdev.max_brightness;
  53         unsigned long long duty =  led_dat->period;
  54
  55         duty *= brightness;
  56         do_div(duty, max);
  57
  58         if (led_dat->active_low)
  59                 duty = led_dat->period - duty;
  60
  61         led_dat->duty = duty;
  62
  63         __led_pwm_set(led_dat);
  64
  65         return 0;
  66 }
  67
  68 static inline size_t sizeof_pwm_leds_priv(int num_leds)
  69 {
  70         return sizeof(struct led_pwm_priv) +
  71                       (sizeof(struct led_pwm_data) * num_leds);
  72 }
  73
  74 static int led_pwm_add(struct device *dev, struct led_pwm_priv *priv,
  75                        struct led_pwm *led, struct device_node *child)
  76 {
  77         struct led_pwm_data *led_data = &priv->leds[priv->num_leds];
  78         struct pwm_args pargs;
  79         int ret;
  80
  81         led_data->active_low = led->active_low;
  82         led_data->cdev.name = led->name;
  83         led_data->cdev.default_trigger = led->default_trigger;
  84         led_data->cdev.brightness = LED_OFF;
  85         led_data->cdev.max_brightness = led->max_brightness;
  86         led_data->cdev.flags = LED_CORE_SUSPENDRESUME;
  87
  88         if (child)
  89                 led_data->pwm = devm_of_pwm_get(dev, child, NULL);
  90         else
  91                 led_data->pwm = devm_pwm_get(dev, led->name);
  92         if (IS_ERR(led_data->pwm)) {
  93                 ret = PTR_ERR(led_data->pwm);
  94                 if (ret != -EPROBE_DEFER)
  95                         dev_err(dev, "unable to request PWM for %s: %d\n",
  96                                 led->name, ret);
  97                 return ret;
  98         }
  99
 100         led_data->cdev.brightness_set_blocking = led_pwm_set;
 101
 102         /*
 103          * FIXME: pwm_apply_args() should be removed when switching to the
 104          * atomic PWM API.
 105          */
 106         pwm_apply_args(led_data->pwm);
 107
 108         pwm_get_args(led_data->pwm, &pargs);
 109
 110         led_data->period = pargs.period;
 111         if (!led_data->period && (led->pwm_period_ns > 0))
 112                 led_data->period = led->pwm_period_ns;
 113
 114         ret = devm_of_led_classdev_register(dev, child, &led_data->cdev);
 115         if (ret == 0) {
 116                 priv->num_leds++;
 117                 led_pwm_set(&led_data->cdev, led_data->cdev.brightness);
 118         } else {
 119                 dev_err(dev, "failed to register PWM led for %s: %d\n",
 120                         led->name, ret);
 121         }
 122
 123         return ret;
 124 }
 125
 126 static int led_pwm_create_of(struct device *dev, struct led_pwm_priv *priv)
 127 {
 128         struct device_node *child;
 129         struct led_pwm led;
 130         int ret = 0;
 131
 132         memset(&led, 0, sizeof(led));
 133
 134         for_each_child_of_node(dev->of_node, child) {
 135                 led.name = of_get_property(child, "label", NULL) ? :
 136                            child->name;
 137
 138                 led.default_trigger = of_get_property(child,
 139                                                 "linux,default-trigger", NULL);
 140                 led.active_low = of_property_read_bool(child, "active-low");
 141                 of_property_read_u32(child, "max-brightness",
 142                                      &led.max_brightness);
 143
 144                 ret = led_pwm_add(dev, priv, &led, child);
 145                 if (ret) {
 146                         of_node_put(child);
 147                         break;
 148                 }
 149         }
 150
 151         return ret;
 152 }
 153
 154 static int led_pwm_probe(struct platform_device *pdev)
 155 {
 156         struct led_pwm_platform_data *pdata = dev_get_platdata(&pdev->dev);
 157         struct led_pwm_priv *priv;
 158         int count, i;
 159         int ret = 0;
 160
 161         if (pdata)
 162                 count = pdata->num_leds;
 163         else
 164                 count = of_get_child_count(pdev->dev.of_node);
 165
 166         if (!count)
 167                 return -EINVAL;
 168
 169         priv = devm_kzalloc(&pdev->dev, sizeof_pwm_leds_priv(count),
 170                             GFP_KERNEL);
 171         if (!priv)
 172                 return -ENOMEM;
 173
 174         if (pdata) {
 175                 for (i = 0; i < count; i++) {
 176                         ret = led_pwm_add(&pdev->dev, priv, &pdata->leds[i],
 177                                           NULL);
 178                         if (ret)
 179                                 break;
 180                 }
 181         } else {
 182                 ret = led_pwm_create_of(&pdev->dev, priv);
 183         }
 184
 185         if (ret)
 186                 return ret;
 187
 188         platform_set_drvdata(pdev, priv);
 189
 190         return 0;
 191 }
 192
 193 static const struct of_device_id of_pwm_leds_match[] = {
 194         { .compatible = "pwm-leds", },
 195         {},
 196 };
 197 MODULE_DEVICE_TABLE(of, of_pwm_leds_match);
 198
 199 static struct platform_driver led_pwm_driver = {
 200         .probe          = led_pwm_probe,
 201         .driver         = {
 202                 .name   = "leds_pwm",
 203                 .of_match_table = of_pwm_leds_match,
 204         },
 205 };
 206
 207 module_platform_driver(led_pwm_driver);
 208
 209 MODULE_AUTHOR("Luotao Fu <l.fu@pengutronix.de>");
 210 MODULE_DESCRIPTION("generic PWM LED driver");
 211 MODULE_LICENSE("GPL v2");
 212 MODULE_ALIAS("platform:leds-pwm");