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 int led_pwm_add(struct device *dev, struct led_pwm_priv *priv,
  69                        struct led_pwm *led, struct fwnode_handle *fwnode)
  70 {
  71         struct led_pwm_data *led_data = &priv->leds[priv->num_leds];
  72         struct pwm_args pargs;
  73         int ret;
  74
  75         led_data->active_low = led->active_low;
  76         led_data->cdev.name = led->name;
  77         led_data->cdev.default_trigger = led->default_trigger;
  78         led_data->cdev.brightness = LED_OFF;
  79         led_data->cdev.max_brightness = led->max_brightness;
  80         led_data->cdev.flags = LED_CORE_SUSPENDRESUME;
  81
  82         if (fwnode)
  83                 led_data->pwm = devm_fwnode_pwm_get(dev, fwnode, NULL);
  84         else
  85                 led_data->pwm = devm_pwm_get(dev, led->name);
  86         if (IS_ERR(led_data->pwm)) {
  87                 ret = PTR_ERR(led_data->pwm);
  88                 if (ret != -EPROBE_DEFER)
  89                         dev_err(dev, "unable to request PWM for %s: %d\n",
  90                                 led->name, ret);
  91                 return ret;
  92         }
  93
  94         led_data->cdev.brightness_set_blocking = led_pwm_set;
  95
  96         /*
  97          * FIXME: pwm_apply_args() should be removed when switching to the
  98          * atomic PWM API.
  99          */
 100         pwm_apply_args(led_data->pwm);
 101
 102         pwm_get_args(led_data->pwm, &pargs);
 103
 104         led_data->period = pargs.period;
 105         if (!led_data->period && (led->pwm_period_ns > 0))
 106                 led_data->period = led->pwm_period_ns;
 107
 108         ret = devm_led_classdev_register(dev, &led_data->cdev);
 109         if (ret == 0) {
 110                 priv->num_leds++;
 111                 led_pwm_set(&led_data->cdev, led_data->cdev.brightness);
 112         } else {
 113                 dev_err(dev, "failed to register PWM led for %s: %d\n",
 114                         led->name, ret);
 115         }
 116
 117         return ret;
 118 }
 119
 120 static int led_pwm_create_fwnode(struct device *dev, struct led_pwm_priv *priv)
 121 {
 122         struct fwnode_handle *fwnode;
 123         struct led_pwm led;
 124         int ret = 0;
 125
 126         memset(&led, 0, sizeof(led));
 127
 128         device_for_each_child_node(dev, fwnode) {
 129                 ret = fwnode_property_read_string(fwnode, "label", &led.name);
 130                 if (ret && is_of_node(fwnode))
 131                         led.name = to_of_node(fwnode)->name;
 132
 133                 if (!led.name) {
 134                         fwnode_handle_put(fwnode);
 135                         return -EINVAL;
 136                 }
 137
 138                 fwnode_property_read_string(fwnode, "linux,default-trigger",
 139                                             &led.default_trigger);
 140
 141                 led.active_low = fwnode_property_read_bool(fwnode,
 142                                                            "active-low");
 143                 fwnode_property_read_u32(fwnode, "max-brightness",
 144                                          &led.max_brightness);
 145
 146                 ret = led_pwm_add(dev, priv, &led, fwnode);
 147                 if (ret) {
 148                         fwnode_handle_put(fwnode);
 149                         break;
 150                 }
 151         }
 152
 153         return ret;
 154 }
 155
 156 static int led_pwm_probe(struct platform_device *pdev)
 157 {
 158         struct led_pwm_platform_data *pdata = dev_get_platdata(&pdev->dev);
 159         struct led_pwm_priv *priv;
 160         int count, i;
 161         int ret = 0;
 162
 163         if (pdata)
 164                 count = pdata->num_leds;
 165         else
 166                 count = device_get_child_node_count(&pdev->dev);
 167
 168         if (!count)
 169                 return -EINVAL;
 170
 171         priv = devm_kzalloc(&pdev->dev, struct_size(priv, leds, count),
 172                             GFP_KERNEL);
 173         if (!priv)
 174                 return -ENOMEM;
 175
 176         if (pdata) {
 177                 for (i = 0; i < count; i++) {
 178                         ret = led_pwm_add(&pdev->dev, priv, &pdata->leds[i],
 179                                           NULL);
 180                         if (ret)
 181                                 break;
 182                 }
 183         } else {
 184                 ret = led_pwm_create_fwnode(&pdev->dev, priv);
 185         }
 186
 187         if (ret)
 188                 return ret;
 189
 190         platform_set_drvdata(pdev, priv);
 191
 192         return 0;
 193 }
 194
 195 static const struct of_device_id of_pwm_leds_match[] = {
 196         { .compatible = "pwm-leds", },
 197         {},
 198 };
 199 MODULE_DEVICE_TABLE(of, of_pwm_leds_match);
 200
 201 static struct platform_driver led_pwm_driver = {
 202         .probe          = led_pwm_probe,
 203         .driver         = {
 204                 .name   = "leds_pwm",
 205                 .of_match_table = of_pwm_leds_match,
 206         },
 207 };
 208
 209 module_platform_driver(led_pwm_driver);
 210
 211 MODULE_AUTHOR("Luotao Fu <l.fu@pengutronix.de>");
 212 MODULE_DESCRIPTION("generic PWM LED driver");
 213 MODULE_LICENSE("GPL v2");
 214 MODULE_ALIAS("platform:leds-pwm");