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// 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.h>
#include <linux/leds.h>
#include <linux/err.h>
#include <linux/pwm.h>
#include <linux/slab.h>
#include "leds.h"
struct led_pwm {
const char *name;
u8 active_low;
u8 default_state;
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;
/*
* Disabling a PWM doesn't guarantee that it emits the inactive level.
* So keep it on. Only for suspending the PWM should be disabled because
* otherwise it refuses to suspend. The possible downside is that the
* LED might stay (or even go) on.
*/
led_dat->pwmstate.enabled = !(led_cdev->flags & LED_SUSPENDED);
return pwm_apply_might_sleep(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;
/* init PWM state */
switch (led->default_state) {
case LEDS_DEFSTATE_KEEP:
pwm_get_state(led_data->pwm, &led_data->pwmstate);
if (led_data->pwmstate.period)
break;
led->default_state = LEDS_DEFSTATE_OFF;
dev_warn(dev,
"failed to read period for %s, default to off",
led->name);
fallthrough;
default:
pwm_init_state(led_data->pwm, &led_data->pwmstate);
break;
}
/* set brightness */
switch (led->default_state) {
case LEDS_DEFSTATE_ON:
led_data->cdev.brightness = led->max_brightness;
break;
case LEDS_DEFSTATE_KEEP:
{
uint64_t brightness;
brightness = led->max_brightness;
brightness *= led_data->pwmstate.duty_cycle;
do_div(brightness, led_data->pwmstate.period);
led_data->cdev.brightness = brightness;
}
break;
}
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;
}
if (led->default_state != LEDS_DEFSTATE_KEEP) {
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;
device_for_each_child_node(dev, fwnode) {
memset(&led, 0, sizeof(led));
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) {
ret = -EINVAL;
goto err_child_out;
}
led.active_low = fwnode_property_read_bool(fwnode,
"active-low");
fwnode_property_read_u32(fwnode, "max-brightness",
&led.max_brightness);
led.default_state = led_init_default_state_get(fwnode);
ret = led_pwm_add(dev, priv, &led, fwnode);
if (ret)
goto err_child_out;
}
return 0;
err_child_out:
fwnode_handle_put(fwnode);
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");
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