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/slab.h>
  20
  21 struct led_pwm {
  22         const char      *name;
  23         const char      *default_trigger;
  24         u8              active_low;
  25         unsigned int    max_brightness;
  26 };
  27
  28 struct led_pwm_platform_data {
  29         int             num_leds;
  30         struct led_pwm  *leds;
  31 };
  32
  33 struct led_pwm_data {
  34         struct led_classdev     cdev;
  35         struct pwm_device       *pwm;
  36         struct pwm_state        pwmstate;
  37         unsigned int            active_low;
  38 };
  39
  40 struct led_pwm_priv {
  41         int num_leds;
  42         struct led_pwm_data leds[];
  43 };
  44
  45 static int led_pwm_set(struct led_classdev *led_cdev,
  46                        enum led_brightness brightness)
  47 {
  48         struct led_pwm_data *led_dat =
  49                 container_of(led_cdev, struct led_pwm_data, cdev);
  50         unsigned int max = led_dat->cdev.max_brightness;
  51         unsigned long long duty = led_dat->pwmstate.period;
  52
  53         duty *= brightness;
  54         do_div(duty, max);
  55
  56         if (led_dat->active_low)
  57                 duty = led_dat->pwmstate.period - duty;
  58
  59         led_dat->pwmstate.duty_cycle = duty;
  60         led_dat->pwmstate.enabled = duty > 0;
  61         return pwm_apply_state(led_dat->pwm, &led_dat->pwmstate);
  62 }
  63
  64 static int led_pwm_add(struct device *dev, struct led_pwm_priv *priv,
  65                        struct led_pwm *led, struct fwnode_handle *fwnode)
  66 {
  67         struct led_pwm_data *led_data = &priv->leds[priv->num_leds];
  68         int ret;
  69
  70         led_data->active_low = led->active_low;
  71         led_data->cdev.name = led->name;
  72         led_data->cdev.default_trigger = led->default_trigger;
  73         led_data->cdev.brightness = LED_OFF;
  74         led_data->cdev.max_brightness = led->max_brightness;
  75         led_data->cdev.flags = LED_CORE_SUSPENDRESUME;
  76
  77         if (fwnode)
  78                 led_data->pwm = devm_fwnode_pwm_get(dev, fwnode, NULL);
  79         else
  80                 led_data->pwm = devm_pwm_get(dev, led->name);
  81         if (IS_ERR(led_data->pwm)) {
  82                 ret = PTR_ERR(led_data->pwm);
  83                 if (ret != -EPROBE_DEFER)
  84                         dev_err(dev, "unable to request PWM for %s: %d\n",
  85                                 led->name, ret);
  86                 return ret;
  87         }
  88
  89         led_data->cdev.brightness_set_blocking = led_pwm_set;
  90
  91         pwm_init_state(led_data->pwm, &led_data->pwmstate);
  92
  93         ret = devm_led_classdev_register(dev, &led_data->cdev);
  94         if (ret == 0) {
  95                 priv->num_leds++;
  96                 led_pwm_set(&led_data->cdev, led_data->cdev.brightness);
  97         } else {
  98                 dev_err(dev, "failed to register PWM led for %s: %d\n",
  99                         led->name, ret);
 100         }
 101
 102         return ret;
 103 }
 104
 105 static int led_pwm_create_fwnode(struct device *dev, struct led_pwm_priv *priv)
 106 {
 107         struct fwnode_handle *fwnode;
 108         struct led_pwm led;
 109         int ret = 0;
 110
 111         memset(&led, 0, sizeof(led));
 112
 113         device_for_each_child_node(dev, fwnode) {
 114                 ret = fwnode_property_read_string(fwnode, "label", &led.name);
 115                 if (ret && is_of_node(fwnode))
 116                         led.name = to_of_node(fwnode)->name;
 117
 118                 if (!led.name) {
 119                         fwnode_handle_put(fwnode);
 120                         return -EINVAL;
 121                 }
 122
 123                 fwnode_property_read_string(fwnode, "linux,default-trigger",
 124                                             &led.default_trigger);
 125
 126                 led.active_low = fwnode_property_read_bool(fwnode,
 127                                                            "active-low");
 128                 fwnode_property_read_u32(fwnode, "max-brightness",
 129                                          &led.max_brightness);
 130
 131                 ret = led_pwm_add(dev, priv, &led, fwnode);
 132                 if (ret) {
 133                         fwnode_handle_put(fwnode);
 134                         break;
 135                 }
 136         }
 137
 138         return ret;
 139 }
 140
 141 static int led_pwm_probe(struct platform_device *pdev)
 142 {
 143         struct led_pwm_platform_data *pdata = dev_get_platdata(&pdev->dev);
 144         struct led_pwm_priv *priv;
 145         int count, i;
 146         int ret = 0;
 147
 148         if (pdata)
 149                 count = pdata->num_leds;
 150         else
 151                 count = device_get_child_node_count(&pdev->dev);
 152
 153         if (!count)
 154                 return -EINVAL;
 155
 156         priv = devm_kzalloc(&pdev->dev, struct_size(priv, leds, count),
 157                             GFP_KERNEL);
 158         if (!priv)
 159                 return -ENOMEM;
 160
 161         if (pdata) {
 162                 for (i = 0; i < count; i++) {
 163                         ret = led_pwm_add(&pdev->dev, priv, &pdata->leds[i],
 164                                           NULL);
 165                         if (ret)
 166                                 break;
 167                 }
 168         } else {
 169                 ret = led_pwm_create_fwnode(&pdev->dev, priv);
 170         }
 171
 172         if (ret)
 173                 return ret;
 174
 175         platform_set_drvdata(pdev, priv);
 176
 177         return 0;
 178 }
 179
 180 static const struct of_device_id of_pwm_leds_match[] = {
 181         { .compatible = "pwm-leds", },
 182         {},
 183 };
 184 MODULE_DEVICE_TABLE(of, of_pwm_leds_match);
 185
 186 static struct platform_driver led_pwm_driver = {
 187         .probe          = led_pwm_probe,
 188         .driver         = {
 189                 .name   = "leds_pwm",
 190                 .of_match_table = of_pwm_leds_match,
 191         },
 192 };
 193
 194 module_platform_driver(led_pwm_driver);
 195
 196 MODULE_AUTHOR("Luotao Fu <l.fu@pengutronix.de>");
 197 MODULE_DESCRIPTION("generic PWM LED driver");
 198 MODULE_LICENSE("GPL v2");
 199 MODULE_ALIAS("platform:leds-pwm");