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