// SPDX-License-Identifier: GPL-2.0-only /* * linux/drivers/leds-pwm.c * * simple PWM based LED control * * Copyright 2009 Luotao Fu @ Pengutronix (l.fu@pengutronix.de) * * based on leds-gpio.c by Raphael Assenat <raph@8d.com> */ #include <linux/module.h> #include <linux/kernel.h> #include <linux/platform_device.h> #include <linux/of_platform.h> #include <linux/leds.h> #include <linux/err.h> #include <linux/pwm.h> #include <linux/slab.h> struct led_pwm { const char *name; u8 active_low; unsigned int max_brightness; }; struct led_pwm_data { struct led_classdev cdev; struct pwm_device *pwm; struct pwm_state pwmstate; unsigned int active_low; }; struct led_pwm_priv { int num_leds; struct led_pwm_data leds[]; }; static int led_pwm_set(struct led_classdev *led_cdev, enum led_brightness brightness) { struct led_pwm_data *led_dat = container_of(led_cdev, struct led_pwm_data, cdev); unsigned int max = led_dat->cdev.max_brightness; unsigned long long duty = led_dat->pwmstate.period; duty *= brightness; do_div(duty, max); if (led_dat->active_low) duty = led_dat->pwmstate.period - duty; led_dat->pwmstate.duty_cycle = duty; led_dat->pwmstate.enabled = duty > 0; return pwm_apply_state(led_dat->pwm, &led_dat->pwmstate); } __attribute__((nonnull)) static int led_pwm_add(struct device *dev, struct led_pwm_priv *priv, struct led_pwm *led, struct fwnode_handle *fwnode) { struct led_pwm_data *led_data = &priv->leds[priv->num_leds]; struct led_init_data init_data = { .fwnode = fwnode }; int ret; led_data->active_low = led->active_low; led_data->cdev.name = led->name; led_data->cdev.brightness = LED_OFF; led_data->cdev.max_brightness = led->max_brightness; led_data->cdev.flags = LED_CORE_SUSPENDRESUME; led_data->pwm = devm_fwnode_pwm_get(dev, fwnode, NULL); if (IS_ERR(led_data->pwm)) return dev_err_probe(dev, PTR_ERR(led_data->pwm), "unable to request PWM for %s\n", led->name); led_data->cdev.brightness_set_blocking = led_pwm_set; pwm_init_state(led_data->pwm, &led_data->pwmstate); ret = devm_led_classdev_register_ext(dev, &led_data->cdev, &init_data); if (ret) { dev_err(dev, "failed to register PWM led for %s: %d\n", led->name, ret); return ret; } ret = led_pwm_set(&led_data->cdev, led_data->cdev.brightness); if (ret) { dev_err(dev, "failed to set led PWM value for %s: %d", led->name, ret); return ret; } priv->num_leds++; return 0; } static int led_pwm_create_fwnode(struct device *dev, struct led_pwm_priv *priv) { struct fwnode_handle *fwnode; struct led_pwm led; int ret = 0; memset(&led, 0, sizeof(led)); device_for_each_child_node(dev, fwnode) { ret = fwnode_property_read_string(fwnode, "label", &led.name); if (ret && is_of_node(fwnode)) led.name = to_of_node(fwnode)->name; if (!led.name) { fwnode_handle_put(fwnode); return -EINVAL; } led.active_low = fwnode_property_read_bool(fwnode, "active-low"); fwnode_property_read_u32(fwnode, "max-brightness", &led.max_brightness); ret = led_pwm_add(dev, priv, &led, fwnode); if (ret) { fwnode_handle_put(fwnode); break; } } return ret; } static int led_pwm_probe(struct platform_device *pdev) { struct led_pwm_priv *priv; int ret = 0; int count; count = device_get_child_node_count(&pdev->dev); if (!count) return -EINVAL; priv = devm_kzalloc(&pdev->dev, struct_size(priv, leds, count), GFP_KERNEL); if (!priv) return -ENOMEM; ret = led_pwm_create_fwnode(&pdev->dev, priv); if (ret) return ret; platform_set_drvdata(pdev, priv); return 0; } static const struct of_device_id of_pwm_leds_match[] = { { .compatible = "pwm-leds", }, {}, }; MODULE_DEVICE_TABLE(of, of_pwm_leds_match); static struct platform_driver led_pwm_driver = { .probe = led_pwm_probe, .driver = { .name = "leds_pwm", .of_match_table = of_pwm_leds_match, }, }; module_platform_driver(led_pwm_driver); MODULE_AUTHOR("Luotao Fu <l.fu@pengutronix.de>"); MODULE_DESCRIPTION("generic PWM LED driver"); MODULE_LICENSE("GPL v2"); MODULE_ALIAS("platform:leds-pwm");