linux/drivers/leds/leds-gpio.c
Dylan Van Assche d864645276 leds: gpio: Set max brightness to 1
GPIO LEDs only know 2 states: ON or OFF and do not have PWM capabilities.
However, the max brightness is reported as 255.

This patch sets the max brightness value of a GPIO controlled LED to 1.

Tested on my PinePhone 1.2.

Signed-off-by: Dylan Van Assche <me@dylanvanassche.be>
Signed-off-by: Pavel Machek <pavel@ucw.cz>
2021-02-03 15:34:37 +01:00

322 lines
8.1 KiB
C

// SPDX-License-Identifier: GPL-2.0-only
/*
* LEDs driver for GPIOs
*
* Copyright (C) 2007 8D Technologies inc.
* Raphael Assenat <raph@8d.com>
* Copyright (C) 2008 Freescale Semiconductor, Inc.
*/
#include <linux/err.h>
#include <linux/gpio.h>
#include <linux/gpio/consumer.h>
#include <linux/kernel.h>
#include <linux/leds.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/property.h>
#include <linux/slab.h>
struct gpio_led_data {
struct led_classdev cdev;
struct gpio_desc *gpiod;
u8 can_sleep;
u8 blinking;
gpio_blink_set_t platform_gpio_blink_set;
};
static inline struct gpio_led_data *
cdev_to_gpio_led_data(struct led_classdev *led_cdev)
{
return container_of(led_cdev, struct gpio_led_data, cdev);
}
static void gpio_led_set(struct led_classdev *led_cdev,
enum led_brightness value)
{
struct gpio_led_data *led_dat = cdev_to_gpio_led_data(led_cdev);
int level;
if (value == LED_OFF)
level = 0;
else
level = 1;
if (led_dat->blinking) {
led_dat->platform_gpio_blink_set(led_dat->gpiod, level,
NULL, NULL);
led_dat->blinking = 0;
} else {
if (led_dat->can_sleep)
gpiod_set_value_cansleep(led_dat->gpiod, level);
else
gpiod_set_value(led_dat->gpiod, level);
}
}
static int gpio_led_set_blocking(struct led_classdev *led_cdev,
enum led_brightness value)
{
gpio_led_set(led_cdev, value);
return 0;
}
static int gpio_blink_set(struct led_classdev *led_cdev,
unsigned long *delay_on, unsigned long *delay_off)
{
struct gpio_led_data *led_dat = cdev_to_gpio_led_data(led_cdev);
led_dat->blinking = 1;
return led_dat->platform_gpio_blink_set(led_dat->gpiod, GPIO_LED_BLINK,
delay_on, delay_off);
}
static int create_gpio_led(const struct gpio_led *template,
struct gpio_led_data *led_dat, struct device *parent,
struct fwnode_handle *fwnode, gpio_blink_set_t blink_set)
{
struct led_init_data init_data = {};
int ret, state;
led_dat->cdev.default_trigger = template->default_trigger;
led_dat->can_sleep = gpiod_cansleep(led_dat->gpiod);
if (!led_dat->can_sleep)
led_dat->cdev.brightness_set = gpio_led_set;
else
led_dat->cdev.brightness_set_blocking = gpio_led_set_blocking;
led_dat->blinking = 0;
if (blink_set) {
led_dat->platform_gpio_blink_set = blink_set;
led_dat->cdev.blink_set = gpio_blink_set;
}
if (template->default_state == LEDS_GPIO_DEFSTATE_KEEP) {
state = gpiod_get_value_cansleep(led_dat->gpiod);
if (state < 0)
return state;
} else {
state = (template->default_state == LEDS_GPIO_DEFSTATE_ON);
}
led_dat->cdev.brightness = state;
led_dat->cdev.max_brightness = 1;
if (!template->retain_state_suspended)
led_dat->cdev.flags |= LED_CORE_SUSPENDRESUME;
if (template->panic_indicator)
led_dat->cdev.flags |= LED_PANIC_INDICATOR;
if (template->retain_state_shutdown)
led_dat->cdev.flags |= LED_RETAIN_AT_SHUTDOWN;
ret = gpiod_direction_output(led_dat->gpiod, state);
if (ret < 0)
return ret;
if (template->name) {
led_dat->cdev.name = template->name;
ret = devm_led_classdev_register(parent, &led_dat->cdev);
} else {
init_data.fwnode = fwnode;
ret = devm_led_classdev_register_ext(parent, &led_dat->cdev,
&init_data);
}
return ret;
}
struct gpio_leds_priv {
int num_leds;
struct gpio_led_data leds[];
};
static struct gpio_leds_priv *gpio_leds_create(struct platform_device *pdev)
{
struct device *dev = &pdev->dev;
struct fwnode_handle *child;
struct gpio_leds_priv *priv;
int count, ret;
count = device_get_child_node_count(dev);
if (!count)
return ERR_PTR(-ENODEV);
priv = devm_kzalloc(dev, struct_size(priv, leds, count), GFP_KERNEL);
if (!priv)
return ERR_PTR(-ENOMEM);
device_for_each_child_node(dev, child) {
struct gpio_led_data *led_dat = &priv->leds[priv->num_leds];
struct gpio_led led = {};
const char *state = NULL;
/*
* Acquire gpiod from DT with uninitialized label, which
* will be updated after LED class device is registered,
* Only then the final LED name is known.
*/
led.gpiod = devm_fwnode_get_gpiod_from_child(dev, NULL, child,
GPIOD_ASIS,
NULL);
if (IS_ERR(led.gpiod)) {
fwnode_handle_put(child);
return ERR_CAST(led.gpiod);
}
led_dat->gpiod = led.gpiod;
if (!fwnode_property_read_string(child, "default-state",
&state)) {
if (!strcmp(state, "keep"))
led.default_state = LEDS_GPIO_DEFSTATE_KEEP;
else if (!strcmp(state, "on"))
led.default_state = LEDS_GPIO_DEFSTATE_ON;
else
led.default_state = LEDS_GPIO_DEFSTATE_OFF;
}
if (fwnode_property_present(child, "retain-state-suspended"))
led.retain_state_suspended = 1;
if (fwnode_property_present(child, "retain-state-shutdown"))
led.retain_state_shutdown = 1;
if (fwnode_property_present(child, "panic-indicator"))
led.panic_indicator = 1;
ret = create_gpio_led(&led, led_dat, dev, child, NULL);
if (ret < 0) {
fwnode_handle_put(child);
return ERR_PTR(ret);
}
/* Set gpiod label to match the corresponding LED name. */
gpiod_set_consumer_name(led_dat->gpiod,
led_dat->cdev.dev->kobj.name);
priv->num_leds++;
}
return priv;
}
static const struct of_device_id of_gpio_leds_match[] = {
{ .compatible = "gpio-leds", },
{},
};
MODULE_DEVICE_TABLE(of, of_gpio_leds_match);
static struct gpio_desc *gpio_led_get_gpiod(struct device *dev, int idx,
const struct gpio_led *template)
{
struct gpio_desc *gpiod;
unsigned long flags = GPIOF_OUT_INIT_LOW;
int ret;
/*
* This means the LED does not come from the device tree
* or ACPI, so let's try just getting it by index from the
* device, this will hit the board file, if any and get
* the GPIO from there.
*/
gpiod = devm_gpiod_get_index(dev, NULL, idx, GPIOD_OUT_LOW);
if (!IS_ERR(gpiod)) {
gpiod_set_consumer_name(gpiod, template->name);
return gpiod;
}
if (PTR_ERR(gpiod) != -ENOENT)
return gpiod;
/*
* This is the legacy code path for platform code that
* still uses GPIO numbers. Ultimately we would like to get
* rid of this block completely.
*/
/* skip leds that aren't available */
if (!gpio_is_valid(template->gpio))
return ERR_PTR(-ENOENT);
if (template->active_low)
flags |= GPIOF_ACTIVE_LOW;
ret = devm_gpio_request_one(dev, template->gpio, flags,
template->name);
if (ret < 0)
return ERR_PTR(ret);
gpiod = gpio_to_desc(template->gpio);
if (!gpiod)
return ERR_PTR(-EINVAL);
return gpiod;
}
static int gpio_led_probe(struct platform_device *pdev)
{
struct gpio_led_platform_data *pdata = dev_get_platdata(&pdev->dev);
struct gpio_leds_priv *priv;
int i, ret = 0;
if (pdata && pdata->num_leds) {
priv = devm_kzalloc(&pdev->dev, struct_size(priv, leds, pdata->num_leds),
GFP_KERNEL);
if (!priv)
return -ENOMEM;
priv->num_leds = pdata->num_leds;
for (i = 0; i < priv->num_leds; i++) {
const struct gpio_led *template = &pdata->leds[i];
struct gpio_led_data *led_dat = &priv->leds[i];
if (template->gpiod)
led_dat->gpiod = template->gpiod;
else
led_dat->gpiod =
gpio_led_get_gpiod(&pdev->dev,
i, template);
if (IS_ERR(led_dat->gpiod)) {
dev_info(&pdev->dev, "Skipping unavailable LED gpio %d (%s)\n",
template->gpio, template->name);
continue;
}
ret = create_gpio_led(template, led_dat,
&pdev->dev, NULL,
pdata->gpio_blink_set);
if (ret < 0)
return ret;
}
} else {
priv = gpio_leds_create(pdev);
if (IS_ERR(priv))
return PTR_ERR(priv);
}
platform_set_drvdata(pdev, priv);
return 0;
}
static void gpio_led_shutdown(struct platform_device *pdev)
{
struct gpio_leds_priv *priv = platform_get_drvdata(pdev);
int i;
for (i = 0; i < priv->num_leds; i++) {
struct gpio_led_data *led = &priv->leds[i];
if (!(led->cdev.flags & LED_RETAIN_AT_SHUTDOWN))
gpio_led_set(&led->cdev, LED_OFF);
}
}
static struct platform_driver gpio_led_driver = {
.probe = gpio_led_probe,
.shutdown = gpio_led_shutdown,
.driver = {
.name = "leds-gpio",
.of_match_table = of_gpio_leds_match,
},
};
module_platform_driver(gpio_led_driver);
MODULE_AUTHOR("Raphael Assenat <raph@8d.com>, Trent Piepho <tpiepho@freescale.com>");
MODULE_DESCRIPTION("GPIO LED driver");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:leds-gpio");