#include <linux/backlight.h>
#include <linux/leds.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/platform_device.h>
struct led_bl_data {
struct device *dev;
struct backlight_device *bl_dev;
struct led_classdev **leds;
bool enabled;
int nb_leds;
unsigned int *levels;
unsigned int default_brightness;
unsigned int max_brightness;
};
static void led_bl_set_brightness(struct led_bl_data *priv, int level)
{
int i;
int bkl_brightness;
if (priv->levels)
bkl_brightness = priv->levels[level];
else
bkl_brightness = level;
for (i = 0; i < priv->nb_leds; i++)
led_set_brightness(priv->leds[i], bkl_brightness);
priv->enabled = true;
}
static void led_bl_power_off(struct led_bl_data *priv)
{
int i;
if (!priv->enabled)
return;
for (i = 0; i < priv->nb_leds; i++)
led_set_brightness(priv->leds[i], LED_OFF);
priv->enabled = false;
}
static int led_bl_update_status(struct backlight_device *bl)
{
struct led_bl_data *priv = bl_get_data(bl);
int brightness = backlight_get_brightness(bl);
if (brightness > 0)
led_bl_set_brightness(priv, brightness);
else
led_bl_power_off(priv);
return 0;
}
static const struct backlight_ops led_bl_ops = {
.update_status = led_bl_update_status,
};
static int led_bl_get_leds(struct device *dev,
struct led_bl_data *priv)
{
int i, nb_leds, ret;
struct device_node *node = dev->of_node;
struct led_classdev **leds;
unsigned int max_brightness;
unsigned int default_brightness;
ret = of_count_phandle_with_args(node, "leds", NULL);
if (ret < 0) {
dev_err(dev, "Unable to get led count\n");
return -EINVAL;
}
nb_leds = ret;
if (nb_leds < 1) {
dev_err(dev, "At least one LED must be specified!\n");
return -EINVAL;
}
leds = devm_kcalloc(dev, nb_leds, sizeof(struct led_classdev *),
GFP_KERNEL);
if (!leds)
return -ENOMEM;
for (i = 0; i < nb_leds; i++) {
leds[i] = devm_of_led_get(dev, i);
if (IS_ERR(leds[i]))
return PTR_ERR(leds[i]);
}
max_brightness = leds[0]->max_brightness;
for (i = 1; i < nb_leds; i++) {
if (max_brightness != leds[i]->max_brightness) {
dev_err(dev, "LEDs must have identical ranges\n");
return -EINVAL;
}
}
default_brightness = leds[0]->brightness;
priv->nb_leds = nb_leds;
priv->leds = leds;
priv->max_brightness = max_brightness;
priv->default_brightness = default_brightness;
return 0;
}
static int led_bl_parse_levels(struct device *dev,
struct led_bl_data *priv)
{
struct device_node *node = dev->of_node;
int num_levels;
u32 value;
int ret;
if (!node)
return -ENODEV;
num_levels = of_property_count_u32_elems(node, "brightness-levels");
if (num_levels > 1) {
int i;
unsigned int db;
u32 *levels = NULL;
levels = devm_kcalloc(dev, num_levels, sizeof(u32),
GFP_KERNEL);
if (!levels)
return -ENOMEM;
ret = of_property_read_u32_array(node, "brightness-levels",
levels,
num_levels);
if (ret < 0)
return ret;
db = priv->default_brightness;
for (i = 0 ; i < num_levels; i++) {
if ((i && db > levels[i-1]) && db <= levels[i])
break;
}
priv->default_brightness = i;
priv->max_brightness = num_levels - 1;
priv->levels = levels;
} else if (num_levels >= 0)
dev_warn(dev, "Not enough levels defined\n");
ret = of_property_read_u32(node, "default-brightness-level", &value);
if (!ret && value <= priv->max_brightness)
priv->default_brightness = value;
else if (!ret && value > priv->max_brightness)
dev_warn(dev, "Invalid default brightness. Ignoring it\n");
return 0;
}
static int led_bl_probe(struct platform_device *pdev)
{
struct backlight_properties props;
struct led_bl_data *priv;
int ret, i;
priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
if (!priv)
return -ENOMEM;
platform_set_drvdata(pdev, priv);
priv->dev = &pdev->dev;
ret = led_bl_get_leds(&pdev->dev, priv);
if (ret)
return ret;
ret = led_bl_parse_levels(&pdev->dev, priv);
if (ret < 0) {
dev_err(&pdev->dev, "Failed to parse DT data\n");
return ret;
}
memset(&props, 0, sizeof(struct backlight_properties));
props.type = BACKLIGHT_RAW;
props.max_brightness = priv->max_brightness;
props.brightness = priv->default_brightness;
props.power = (priv->default_brightness > 0) ? BACKLIGHT_POWER_OFF :
BACKLIGHT_POWER_ON;
priv->bl_dev = backlight_device_register(dev_name(&pdev->dev),
&pdev->dev, priv, &led_bl_ops, &props);
if (IS_ERR(priv->bl_dev)) {
dev_err(&pdev->dev, "Failed to register backlight\n");
return PTR_ERR(priv->bl_dev);
}
for (i = 0; i < priv->nb_leds; i++) {
struct device_link *link;
link = device_link_add(&pdev->dev, priv->leds[i]->dev->parent,
DL_FLAG_AUTOREMOVE_CONSUMER);
if (!link) {
dev_err(&pdev->dev, "Failed to add devlink (consumer %s, supplier %s)\n",
dev_name(&pdev->dev), dev_name(priv->leds[i]->dev->parent));
backlight_device_unregister(priv->bl_dev);
return -EINVAL;
}
}
for (i = 0; i < priv->nb_leds; i++) {
mutex_lock(&priv->leds[i]->led_access);
led_sysfs_disable(priv->leds[i]);
mutex_unlock(&priv->leds[i]->led_access);
}
backlight_update_status(priv->bl_dev);
return 0;
}
static void led_bl_remove(struct platform_device *pdev)
{
struct led_bl_data *priv = platform_get_drvdata(pdev);
struct backlight_device *bl = priv->bl_dev;
int i;
backlight_device_unregister(bl);
led_bl_power_off(priv);
for (i = 0; i < priv->nb_leds; i++) {
mutex_lock(&priv->leds[i]->led_access);
led_sysfs_enable(priv->leds[i]);
mutex_unlock(&priv->leds[i]->led_access);
}
}
static const struct of_device_id led_bl_of_match[] = {
{ .compatible = "led-backlight" },
{ }
};
MODULE_DEVICE_TABLE(of, led_bl_of_match);
static struct platform_driver led_bl_driver = {
.driver = {
.name = "led-backlight",
.of_match_table = led_bl_of_match,
},
.probe = led_bl_probe,
.remove = led_bl_remove,
};
module_platform_driver(led_bl_driver);
MODULE_DESCRIPTION("LED based Backlight Driver");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:led-backlight");
