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- // SPDX-License-Identifier: GPL-2.0
- /*
- * Copyright (C) 2015-2019 Texas Instruments Incorporated - http://www.ti.com/
- * Author: Tomi Valkeinen <tomi.valkeinen@ti.com>
- *
- * Based on pwm_bl.c
- */
- #include <linux/backlight.h>
- #include <linux/leds.h>
- #include <linux/module.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_kzalloc(dev, sizeof(struct led_classdev *) * nb_leds,
- 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]);
- }
- /* check that the LEDs all have the same brightness range */
- 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;
- }
- }
- /* get the default brightness from the first LED from the list */
- 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_kzalloc(dev, sizeof(u32) * num_levels,
- GFP_KERNEL);
- if (!levels)
- return -ENOMEM;
- ret = of_property_read_u32_array(node, "brightness-levels",
- levels,
- num_levels);
- if (ret < 0)
- return ret;
- /*
- * Try to map actual LED brightness to backlight brightness
- * level
- */
- 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) ? FB_BLANK_POWERDOWN :
- FB_BLANK_UNBLANK;
- 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++)
- led_sysfs_disable(priv->leds[i]);
- backlight_update_status(priv->bl_dev);
- return 0;
- }
- static int 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++)
- led_sysfs_enable(priv->leds[i]);
- return 0;
- }
- 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 = of_match_ptr(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");
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