drivers/leds/rgb/leds-pwm-multicolor.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * PWM-based multi-color LED control
   4  *
   5  * Copyright 2022 Sven Schwermer <[email protected]>
   6  */
   7
   8 #include <linux/err.h>
   9 #include <linux/kernel.h>
  10 #include <linux/led-class-multicolor.h>
  11 #include <linux/leds.h>
  12 #include <linux/mod_devicetable.h>
  13 #include <linux/module.h>
  14 #include <linux/mutex.h>
  15 #include <linux/platform_device.h>
  16 #include <linux/property.h>
  17 #include <linux/pwm.h>
  18
  19 struct pwm_led {
  20         struct pwm_device *pwm;
  21         struct pwm_state state;
  22         bool active_low;
  23 };
  24
  25 struct pwm_mc_led {
  26         struct led_classdev_mc mc_cdev;
  27         struct mutex lock;
  28         struct pwm_led leds[];
  29 };
  30
  31 static int led_pwm_mc_set(struct led_classdev *cdev,
  32                           enum led_brightness brightness)
  33 {
  34         struct led_classdev_mc *mc_cdev = lcdev_to_mccdev(cdev);
  35         struct pwm_mc_led *priv = container_of(mc_cdev, struct pwm_mc_led, mc_cdev);
  36         unsigned long long duty;
  37         int ret = 0;
  38         int i;
  39
  40         led_mc_calc_color_components(mc_cdev, brightness);
  41
  42         mutex_lock(&priv->lock);
  43
  44         for (i = 0; i < mc_cdev->num_colors; i++) {
  45                 duty = priv->leds[i].state.period;
  46                 duty *= mc_cdev->subled_info[i].brightness;
  47                 do_div(duty, cdev->max_brightness);
  48
  49                 if (priv->leds[i].active_low)
  50                         duty = priv->leds[i].state.period - duty;
  51
  52                 priv->leds[i].state.duty_cycle = duty;
  53                 priv->leds[i].state.enabled = duty > 0;
  54                 ret = pwm_apply_state(priv->leds[i].pwm,
  55                                       &priv->leds[i].state);
  56                 if (ret)
  57                         break;
  58         }
  59
  60         mutex_unlock(&priv->lock);
  61
  62         return ret;
  63 }
  64
  65 static int iterate_subleds(struct device *dev, struct pwm_mc_led *priv,
  66                            struct fwnode_handle *mcnode)
  67 {
  68         struct mc_subled *subled = priv->mc_cdev.subled_info;
  69         struct fwnode_handle *fwnode;
  70         struct pwm_led *pwmled;
  71         u32 color;
  72         int ret;
  73
  74         /* iterate over the nodes inside the multi-led node */
  75         fwnode_for_each_child_node(mcnode, fwnode) {
  76                 pwmled = &priv->leds[priv->mc_cdev.num_colors];
  77                 pwmled->pwm = devm_fwnode_pwm_get(dev, fwnode, NULL);
  78                 if (IS_ERR(pwmled->pwm)) {
  79                         ret = dev_err_probe(dev, PTR_ERR(pwmled->pwm), "unable to request PWM\n");
  80                         goto release_fwnode;
  81                 }
  82                 pwm_init_state(pwmled->pwm, &pwmled->state);
  83                 pwmled->active_low = fwnode_property_read_bool(fwnode, "active-low");
  84
  85                 ret = fwnode_property_read_u32(fwnode, "color", &color);
  86                 if (ret) {
  87                         dev_err(dev, "cannot read color: %d\n", ret);
  88                         goto release_fwnode;
  89                 }
  90
  91                 subled[priv->mc_cdev.num_colors].color_index = color;
  92                 priv->mc_cdev.num_colors++;
  93         }
  94
  95         return 0;
  96
  97 release_fwnode:
  98         fwnode_handle_put(fwnode);
  99         return ret;
 100 }
 101
 102 static int led_pwm_mc_probe(struct platform_device *pdev)
 103 {
 104         struct fwnode_handle *mcnode, *fwnode;
 105         struct led_init_data init_data = {};
 106         struct led_classdev *cdev;
 107         struct mc_subled *subled;
 108         struct pwm_mc_led *priv;
 109         int count = 0;
 110         int ret = 0;
 111
 112         mcnode = device_get_named_child_node(&pdev->dev, "multi-led");
 113         if (!mcnode)
 114                 return dev_err_probe(&pdev->dev, -ENODEV,
 115                                      "expected multi-led node\n");
 116
 117         /* count the nodes inside the multi-led node */
 118         fwnode_for_each_child_node(mcnode, fwnode)
 119                 count++;
 120
 121         priv = devm_kzalloc(&pdev->dev, struct_size(priv, leds, count),
 122                             GFP_KERNEL);
 123         if (!priv) {
 124                 ret = -ENOMEM;
 125                 goto release_mcnode;
 126         }
 127         mutex_init(&priv->lock);
 128
 129         subled = devm_kcalloc(&pdev->dev, count, sizeof(*subled), GFP_KERNEL);
 130         if (!subled) {
 131                 ret = -ENOMEM;
 132                 goto release_mcnode;
 133         }
 134         priv->mc_cdev.subled_info = subled;
 135
 136         /* init the multicolor's LED class device */
 137         cdev = &priv->mc_cdev.led_cdev;
 138         fwnode_property_read_u32(mcnode, "max-brightness",
 139                                  &cdev->max_brightness);
 140         cdev->flags = LED_CORE_SUSPENDRESUME;
 141         cdev->brightness_set_blocking = led_pwm_mc_set;
 142
 143         ret = iterate_subleds(&pdev->dev, priv, mcnode);
 144         if (ret)
 145                 goto release_mcnode;
 146
 147         init_data.fwnode = mcnode;
 148         ret = devm_led_classdev_multicolor_register_ext(&pdev->dev,
 149                                                         &priv->mc_cdev,
 150                                                         &init_data);
 151         if (ret) {
 152                 dev_err(&pdev->dev,
 153                         "failed to register multicolor PWM led for %s: %d\n",
 154                         cdev->name, ret);
 155                 goto release_mcnode;
 156         }
 157
 158         ret = led_pwm_mc_set(cdev, cdev->brightness);
 159         if (ret)
 160                 return dev_err_probe(&pdev->dev, ret,
 161                                      "failed to set led PWM value for %s: %d",
 162                                      cdev->name, ret);
 163
 164         platform_set_drvdata(pdev, priv);
 165         return 0;
 166
 167 release_mcnode:
 168         fwnode_handle_put(mcnode);
 169         return ret;
 170 }
 171
 172 static const struct of_device_id of_pwm_leds_mc_match[] = {
 173         { .compatible = "pwm-leds-multicolor", },
 174         {}
 175 };
 176 MODULE_DEVICE_TABLE(of, of_pwm_leds_mc_match);
 177
 178 static struct platform_driver led_pwm_mc_driver = {
 179         .probe          = led_pwm_mc_probe,
 180         .driver         = {
 181                 .name   = "leds_pwm_multicolor",
 182                 .of_match_table = of_pwm_leds_mc_match,
 183         },
 184 };
 185 module_platform_driver(led_pwm_mc_driver);
 186
 187 MODULE_AUTHOR("Sven Schwermer <[email protected]>");
 188 MODULE_DESCRIPTION("multi-color PWM LED driver");
 189 MODULE_LICENSE("GPL v2");
 190 MODULE_ALIAS("platform:leds-pwm-multicolor");