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1// SPDX-License-Identifier: GPL-2.0-only2/*3 * linux/drivers/leds-pwm.c4 *5 * simple PWM based LED control6 *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.h>16#include <linux/leds.h>17#include <linux/err.h>18#include <linux/pwm.h>19#include <linux/slab.h>20#include "leds.h"21 22struct led_pwm {23 const char *name;24 u8 active_low;25 u8 default_state;26 unsigned int max_brightness;27};28 29struct led_pwm_data {30 struct led_classdev cdev;31 struct pwm_device *pwm;32 struct pwm_state pwmstate;33 unsigned int active_low;34};35 36struct led_pwm_priv {37 int num_leds;38 struct led_pwm_data leds[];39};40 41static int led_pwm_set(struct led_classdev *led_cdev,42 enum led_brightness brightness)43{44 struct led_pwm_data *led_dat =45 container_of(led_cdev, struct led_pwm_data, cdev);46 unsigned int max = led_dat->cdev.max_brightness;47 unsigned long long duty = led_dat->pwmstate.period;48 49 duty *= brightness;50 do_div(duty, max);51 52 if (led_dat->active_low)53 duty = led_dat->pwmstate.period - duty;54 55 led_dat->pwmstate.duty_cycle = duty;56 /*57 * Disabling a PWM doesn't guarantee that it emits the inactive level.58 * So keep it on. Only for suspending the PWM should be disabled because59 * otherwise it refuses to suspend. The possible downside is that the60 * LED might stay (or even go) on.61 */62 led_dat->pwmstate.enabled = !(led_cdev->flags & LED_SUSPENDED);63 return pwm_apply_might_sleep(led_dat->pwm, &led_dat->pwmstate);64}65 66__attribute__((nonnull))67static int led_pwm_add(struct device *dev, struct led_pwm_priv *priv,68 struct led_pwm *led, struct fwnode_handle *fwnode)69{70 struct led_pwm_data *led_data = &priv->leds[priv->num_leds];71 struct led_init_data init_data = { .fwnode = fwnode };72 int ret;73 74 led_data->active_low = led->active_low;75 led_data->cdev.name = led->name;76 led_data->cdev.brightness = LED_OFF;77 led_data->cdev.max_brightness = led->max_brightness;78 led_data->cdev.flags = LED_CORE_SUSPENDRESUME;79 80 led_data->pwm = devm_fwnode_pwm_get(dev, fwnode, NULL);81 if (IS_ERR(led_data->pwm))82 return dev_err_probe(dev, PTR_ERR(led_data->pwm),83 "unable to request PWM for %s\n",84 led->name);85 86 led_data->cdev.brightness_set_blocking = led_pwm_set;87 88 /* init PWM state */89 switch (led->default_state) {90 case LEDS_DEFSTATE_KEEP:91 pwm_get_state(led_data->pwm, &led_data->pwmstate);92 if (led_data->pwmstate.period)93 break;94 led->default_state = LEDS_DEFSTATE_OFF;95 dev_warn(dev,96 "failed to read period for %s, default to off",97 led->name);98 fallthrough;99 default:100 pwm_init_state(led_data->pwm, &led_data->pwmstate);101 break;102 }103 104 /* set brightness */105 switch (led->default_state) {106 case LEDS_DEFSTATE_ON:107 led_data->cdev.brightness = led->max_brightness;108 break;109 case LEDS_DEFSTATE_KEEP:110 {111 uint64_t brightness;112 113 brightness = led->max_brightness;114 brightness *= led_data->pwmstate.duty_cycle;115 do_div(brightness, led_data->pwmstate.period);116 led_data->cdev.brightness = brightness;117 }118 break;119 }120 121 ret = devm_led_classdev_register_ext(dev, &led_data->cdev, &init_data);122 if (ret) {123 dev_err(dev, "failed to register PWM led for %s: %d\n",124 led->name, ret);125 return ret;126 }127 128 if (led->default_state != LEDS_DEFSTATE_KEEP) {129 ret = led_pwm_set(&led_data->cdev, led_data->cdev.brightness);130 if (ret) {131 dev_err(dev, "failed to set led PWM value for %s: %d",132 led->name, ret);133 return ret;134 }135 }136 137 priv->num_leds++;138 return 0;139}140 141static int led_pwm_create_fwnode(struct device *dev, struct led_pwm_priv *priv)142{143 struct fwnode_handle *fwnode;144 struct led_pwm led;145 int ret;146 147 device_for_each_child_node(dev, fwnode) {148 memset(&led, 0, sizeof(led));149 150 ret = fwnode_property_read_string(fwnode, "label", &led.name);151 if (ret && is_of_node(fwnode))152 led.name = to_of_node(fwnode)->name;153 154 if (!led.name) {155 ret = -EINVAL;156 goto err_child_out;157 }158 159 led.active_low = fwnode_property_read_bool(fwnode,160 "active-low");161 fwnode_property_read_u32(fwnode, "max-brightness",162 &led.max_brightness);163 164 led.default_state = led_init_default_state_get(fwnode);165 166 ret = led_pwm_add(dev, priv, &led, fwnode);167 if (ret)168 goto err_child_out;169 }170 171 return 0;172 173err_child_out:174 fwnode_handle_put(fwnode);175 return ret;176}177 178static int led_pwm_probe(struct platform_device *pdev)179{180 struct led_pwm_priv *priv;181 int ret = 0;182 int count;183 184 count = device_get_child_node_count(&pdev->dev);185 186 if (!count)187 return -EINVAL;188 189 priv = devm_kzalloc(&pdev->dev, struct_size(priv, leds, count),190 GFP_KERNEL);191 if (!priv)192 return -ENOMEM;193 194 ret = led_pwm_create_fwnode(&pdev->dev, priv);195 196 if (ret)197 return ret;198 199 platform_set_drvdata(pdev, priv);200 201 return 0;202}203 204static const struct of_device_id of_pwm_leds_match[] = {205 { .compatible = "pwm-leds", },206 {},207};208MODULE_DEVICE_TABLE(of, of_pwm_leds_match);209 210static struct platform_driver led_pwm_driver = {211 .probe = led_pwm_probe,212 .driver = {213 .name = "leds_pwm",214 .of_match_table = of_pwm_leds_match,215 },216};217 218module_platform_driver(led_pwm_driver);219 220MODULE_AUTHOR("Luotao Fu <l.fu@pengutronix.de>");221MODULE_DESCRIPTION("generic PWM LED driver");222MODULE_LICENSE("GPL v2");223MODULE_ALIAS("platform:leds-pwm");224