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1// SPDX-License-Identifier: GPL-2.02/*3 * Multi-color LED built with monochromatic LED devices4 *5 * This driver groups several monochromatic LED devices in a single multicolor LED device.6 *7 * Compared to handling this grouping in user-space, the benefits are:8 * - The state of the monochromatic LED relative to each other is always consistent.9 * - The sysfs interface of the LEDs can be used for the group as a whole.10 *11 * Copyright 2023 Jean-Jacques Hiblot <jjhiblot@traphandler.com>12 */13 14#include <linux/err.h>15#include <linux/leds.h>16#include <linux/led-class-multicolor.h>17#include <linux/math.h>18#include <linux/module.h>19#include <linux/mod_devicetable.h>20#include <linux/platform_device.h>21#include <linux/property.h>22 23struct leds_multicolor {24 struct led_classdev_mc mc_cdev;25 struct led_classdev **monochromatics;26};27 28static int leds_gmc_set(struct led_classdev *cdev, enum led_brightness brightness)29{30 struct led_classdev_mc *mc_cdev = lcdev_to_mccdev(cdev);31 struct leds_multicolor *priv = container_of(mc_cdev, struct leds_multicolor, mc_cdev);32 const unsigned int group_max_brightness = mc_cdev->led_cdev.max_brightness;33 int i;34 35 for (i = 0; i < mc_cdev->num_colors; i++) {36 struct led_classdev *mono = priv->monochromatics[i];37 const unsigned int mono_max_brightness = mono->max_brightness;38 unsigned int intensity = mc_cdev->subled_info[i].intensity;39 int mono_brightness;40 41 /*42 * Scale the brightness according to relative intensity of the43 * color AND the max brightness of the monochromatic LED.44 */45 mono_brightness = DIV_ROUND_CLOSEST(brightness * intensity * mono_max_brightness,46 group_max_brightness * group_max_brightness);47 48 led_set_brightness(mono, mono_brightness);49 }50 51 return 0;52}53 54static void restore_sysfs_write_access(void *data)55{56 struct led_classdev *led_cdev = data;57 58 /* Restore the write acccess to the LED */59 mutex_lock(&led_cdev->led_access);60 led_sysfs_enable(led_cdev);61 mutex_unlock(&led_cdev->led_access);62}63 64static int leds_gmc_probe(struct platform_device *pdev)65{66 struct device *dev = &pdev->dev;67 struct led_init_data init_data = {};68 struct led_classdev *cdev;69 struct mc_subled *subled;70 struct leds_multicolor *priv;71 unsigned int max_brightness = 0;72 int i, ret, count = 0, common_flags = 0;73 74 priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);75 if (!priv)76 return -ENOMEM;77 78 for (;;) {79 struct led_classdev *led_cdev;80 81 led_cdev = devm_of_led_get_optional(dev, count);82 if (IS_ERR(led_cdev))83 return dev_err_probe(dev, PTR_ERR(led_cdev), "Unable to get LED #%d",84 count);85 if (!led_cdev)86 break;87 88 priv->monochromatics = devm_krealloc_array(dev, priv->monochromatics,89 count + 1, sizeof(*priv->monochromatics),90 GFP_KERNEL);91 if (!priv->monochromatics)92 return -ENOMEM;93 94 common_flags |= led_cdev->flags;95 priv->monochromatics[count] = led_cdev;96 97 max_brightness = max(max_brightness, led_cdev->max_brightness);98 99 count++;100 }101 102 subled = devm_kcalloc(dev, count, sizeof(*subled), GFP_KERNEL);103 if (!subled)104 return -ENOMEM;105 priv->mc_cdev.subled_info = subled;106 107 for (i = 0; i < count; i++) {108 struct led_classdev *led_cdev = priv->monochromatics[i];109 110 subled[i].color_index = led_cdev->color;111 112 /* Configure the LED intensity to its maximum */113 subled[i].intensity = max_brightness;114 }115 116 /* Initialise the multicolor's LED class device */117 cdev = &priv->mc_cdev.led_cdev;118 cdev->brightness_set_blocking = leds_gmc_set;119 cdev->max_brightness = max_brightness;120 cdev->color = LED_COLOR_ID_MULTI;121 priv->mc_cdev.num_colors = count;122 123 /* we only need suspend/resume if a sub-led requests it */124 if (common_flags & LED_CORE_SUSPENDRESUME)125 cdev->flags = LED_CORE_SUSPENDRESUME;126 127 init_data.fwnode = dev_fwnode(dev);128 ret = devm_led_classdev_multicolor_register_ext(dev, &priv->mc_cdev, &init_data);129 if (ret)130 return dev_err_probe(dev, ret, "failed to register multicolor LED for %s.\n",131 cdev->name);132 133 ret = leds_gmc_set(cdev, cdev->brightness);134 if (ret)135 return dev_err_probe(dev, ret, "failed to set LED value for %s.", cdev->name);136 137 for (i = 0; i < count; i++) {138 struct led_classdev *led_cdev = priv->monochromatics[i];139 140 /*141 * Make the individual LED sysfs interface read-only to prevent the user142 * to change the brightness of the individual LEDs of the group.143 */144 mutex_lock(&led_cdev->led_access);145 led_sysfs_disable(led_cdev);146 mutex_unlock(&led_cdev->led_access);147 148 /* Restore the write access to the LED sysfs when the group is destroyed */149 devm_add_action_or_reset(dev, restore_sysfs_write_access, led_cdev);150 }151 152 return 0;153}154 155static const struct of_device_id of_leds_group_multicolor_match[] = {156 { .compatible = "leds-group-multicolor" },157 {}158};159MODULE_DEVICE_TABLE(of, of_leds_group_multicolor_match);160 161static struct platform_driver leds_group_multicolor_driver = {162 .probe = leds_gmc_probe,163 .driver = {164 .name = "leds_group_multicolor",165 .of_match_table = of_leds_group_multicolor_match,166 }167};168module_platform_driver(leds_group_multicolor_driver);169 170MODULE_AUTHOR("Jean-Jacques Hiblot <jjhiblot@traphandler.com>");171MODULE_DESCRIPTION("LEDs group multicolor driver");172MODULE_LICENSE("GPL");173MODULE_ALIAS("platform:leds-group-multicolor");174