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![Denis Osterland-Heim](/assets/img/avatar_default.png)
This patch adds support for "default-state" devicetree property, which allows to defer pwm init to first use of led. This allows to configure the PWM early in bootloader to let the LED blink until an application in Linux userspace sets something different. Signed-off-by: Denis Osterland-Heim <Denis.Osterland@diehl.com> Signed-off-by: Pavel Machek <pavel@ucw.cz>
217 lines
4.9 KiB
C
217 lines
4.9 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* linux/drivers/leds-pwm.c
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*
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* simple PWM based LED control
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*
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* Copyright 2009 Luotao Fu @ Pengutronix (l.fu@pengutronix.de)
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*
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* based on leds-gpio.c by Raphael Assenat <raph@8d.com>
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*/
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#include <linux/module.h>
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#include <linux/kernel.h>
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#include <linux/platform_device.h>
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#include <linux/of_platform.h>
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#include <linux/leds.h>
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#include <linux/err.h>
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#include <linux/pwm.h>
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#include <linux/slab.h>
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#include "leds.h"
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struct led_pwm {
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const char *name;
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u8 active_low;
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u8 default_state;
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unsigned int max_brightness;
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};
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struct led_pwm_data {
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struct led_classdev cdev;
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struct pwm_device *pwm;
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struct pwm_state pwmstate;
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unsigned int active_low;
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};
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struct led_pwm_priv {
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int num_leds;
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struct led_pwm_data leds[];
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};
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static int led_pwm_set(struct led_classdev *led_cdev,
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enum led_brightness brightness)
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{
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struct led_pwm_data *led_dat =
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container_of(led_cdev, struct led_pwm_data, cdev);
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unsigned int max = led_dat->cdev.max_brightness;
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unsigned long long duty = led_dat->pwmstate.period;
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duty *= brightness;
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do_div(duty, max);
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if (led_dat->active_low)
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duty = led_dat->pwmstate.period - duty;
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led_dat->pwmstate.duty_cycle = duty;
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led_dat->pwmstate.enabled = duty > 0;
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return pwm_apply_state(led_dat->pwm, &led_dat->pwmstate);
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}
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__attribute__((nonnull))
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static int led_pwm_add(struct device *dev, struct led_pwm_priv *priv,
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struct led_pwm *led, struct fwnode_handle *fwnode)
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{
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struct led_pwm_data *led_data = &priv->leds[priv->num_leds];
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struct led_init_data init_data = { .fwnode = fwnode };
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int ret;
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led_data->active_low = led->active_low;
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led_data->cdev.name = led->name;
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led_data->cdev.brightness = LED_OFF;
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led_data->cdev.max_brightness = led->max_brightness;
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led_data->cdev.flags = LED_CORE_SUSPENDRESUME;
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led_data->pwm = devm_fwnode_pwm_get(dev, fwnode, NULL);
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if (IS_ERR(led_data->pwm))
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return dev_err_probe(dev, PTR_ERR(led_data->pwm),
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"unable to request PWM for %s\n",
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led->name);
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led_data->cdev.brightness_set_blocking = led_pwm_set;
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/* init PWM state */
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switch (led->default_state) {
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case LEDS_DEFSTATE_KEEP:
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pwm_get_state(led_data->pwm, &led_data->pwmstate);
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if (led_data->pwmstate.period)
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break;
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led->default_state = LEDS_DEFSTATE_OFF;
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dev_warn(dev,
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"failed to read period for %s, default to off",
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led->name);
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fallthrough;
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default:
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pwm_init_state(led_data->pwm, &led_data->pwmstate);
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break;
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}
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/* set brightness */
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switch (led->default_state) {
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case LEDS_DEFSTATE_ON:
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led_data->cdev.brightness = led->max_brightness;
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break;
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case LEDS_DEFSTATE_KEEP:
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{
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uint64_t brightness;
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brightness = led->max_brightness;
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brightness *= led_data->pwmstate.duty_cycle;
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do_div(brightness, led_data->pwmstate.period);
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led_data->cdev.brightness = brightness;
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}
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break;
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}
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ret = devm_led_classdev_register_ext(dev, &led_data->cdev, &init_data);
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if (ret) {
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dev_err(dev, "failed to register PWM led for %s: %d\n",
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led->name, ret);
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return ret;
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}
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if (led->default_state != LEDS_DEFSTATE_KEEP) {
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ret = led_pwm_set(&led_data->cdev, led_data->cdev.brightness);
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if (ret) {
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dev_err(dev, "failed to set led PWM value for %s: %d",
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led->name, ret);
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return ret;
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}
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}
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priv->num_leds++;
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return 0;
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}
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static int led_pwm_create_fwnode(struct device *dev, struct led_pwm_priv *priv)
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{
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struct fwnode_handle *fwnode;
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struct led_pwm led;
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int ret;
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memset(&led, 0, sizeof(led));
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device_for_each_child_node(dev, fwnode) {
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ret = fwnode_property_read_string(fwnode, "label", &led.name);
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if (ret && is_of_node(fwnode))
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led.name = to_of_node(fwnode)->name;
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if (!led.name) {
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ret = EINVAL;
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goto err_child_out;
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}
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led.active_low = fwnode_property_read_bool(fwnode,
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"active-low");
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fwnode_property_read_u32(fwnode, "max-brightness",
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&led.max_brightness);
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led.default_state = led_init_default_state_get(fwnode);
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ret = led_pwm_add(dev, priv, &led, fwnode);
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if (ret)
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goto err_child_out;
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}
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return 0;
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err_child_out:
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fwnode_handle_put(fwnode);
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return ret;
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}
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static int led_pwm_probe(struct platform_device *pdev)
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{
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struct led_pwm_priv *priv;
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int ret = 0;
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int count;
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count = device_get_child_node_count(&pdev->dev);
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if (!count)
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return -EINVAL;
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priv = devm_kzalloc(&pdev->dev, struct_size(priv, leds, count),
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GFP_KERNEL);
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if (!priv)
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return -ENOMEM;
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ret = led_pwm_create_fwnode(&pdev->dev, priv);
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if (ret)
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return ret;
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platform_set_drvdata(pdev, priv);
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return 0;
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}
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static const struct of_device_id of_pwm_leds_match[] = {
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{ .compatible = "pwm-leds", },
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{},
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};
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MODULE_DEVICE_TABLE(of, of_pwm_leds_match);
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static struct platform_driver led_pwm_driver = {
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.probe = led_pwm_probe,
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.driver = {
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.name = "leds_pwm",
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.of_match_table = of_pwm_leds_match,
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},
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};
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module_platform_driver(led_pwm_driver);
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MODULE_AUTHOR("Luotao Fu <l.fu@pengutronix.de>");
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MODULE_DESCRIPTION("generic PWM LED driver");
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MODULE_LICENSE("GPL v2");
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MODULE_ALIAS("platform:leds-pwm");
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