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ae232e45ac
This patch adds a led-backlight driver (led_bl), which is similar to pwm_bl except the driver uses a LED class driver to adjust the brightness in the HW. Multiple LEDs can be used for a single backlight. Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com> Signed-off-by: Jean-Jacques Hiblot <jjhiblot@ti.com> Acked-by: Pavel Machek <pavel@ucw.cz> Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org> Acked-by: Lee Jones <lee.jones@linaro.org> Acked-by: Tony Lindgren <tony@atomide.com> Tested-by: Tony Lindgren <tony@atomide.com> Tested-by: Guido Günther <agx@sigxcpu.org> Signed-off-by: Pavel Machek <pavel@ucw.cz> Signed-off-by: Tony Lindgren <tony@atomide.com>
261 lines
5.9 KiB
C
261 lines
5.9 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Copyright (C) 2015-2019 Texas Instruments Incorporated - http://www.ti.com/
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* Author: Tomi Valkeinen <tomi.valkeinen@ti.com>
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*
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* Based on pwm_bl.c
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*/
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#include <linux/backlight.h>
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#include <linux/leds.h>
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#include <linux/module.h>
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#include <linux/platform_device.h>
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struct led_bl_data {
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struct device *dev;
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struct backlight_device *bl_dev;
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struct led_classdev **leds;
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bool enabled;
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int nb_leds;
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unsigned int *levels;
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unsigned int default_brightness;
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unsigned int max_brightness;
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};
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static void led_bl_set_brightness(struct led_bl_data *priv, int level)
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{
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int i;
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int bkl_brightness;
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if (priv->levels)
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bkl_brightness = priv->levels[level];
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else
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bkl_brightness = level;
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for (i = 0; i < priv->nb_leds; i++)
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led_set_brightness(priv->leds[i], bkl_brightness);
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priv->enabled = true;
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}
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static void led_bl_power_off(struct led_bl_data *priv)
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{
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int i;
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if (!priv->enabled)
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return;
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for (i = 0; i < priv->nb_leds; i++)
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led_set_brightness(priv->leds[i], LED_OFF);
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priv->enabled = false;
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}
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static int led_bl_update_status(struct backlight_device *bl)
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{
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struct led_bl_data *priv = bl_get_data(bl);
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int brightness = bl->props.brightness;
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if (bl->props.power != FB_BLANK_UNBLANK ||
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bl->props.fb_blank != FB_BLANK_UNBLANK ||
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bl->props.state & BL_CORE_FBBLANK)
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brightness = 0;
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if (brightness > 0)
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led_bl_set_brightness(priv, brightness);
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else
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led_bl_power_off(priv);
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return 0;
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}
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static const struct backlight_ops led_bl_ops = {
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.update_status = led_bl_update_status,
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};
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static int led_bl_get_leds(struct device *dev,
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struct led_bl_data *priv)
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{
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int i, nb_leds, ret;
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struct device_node *node = dev->of_node;
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struct led_classdev **leds;
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unsigned int max_brightness;
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unsigned int default_brightness;
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ret = of_count_phandle_with_args(node, "leds", NULL);
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if (ret < 0) {
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dev_err(dev, "Unable to get led count\n");
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return -EINVAL;
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}
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nb_leds = ret;
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if (nb_leds < 1) {
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dev_err(dev, "At least one LED must be specified!\n");
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return -EINVAL;
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}
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leds = devm_kzalloc(dev, sizeof(struct led_classdev *) * nb_leds,
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GFP_KERNEL);
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if (!leds)
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return -ENOMEM;
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for (i = 0; i < nb_leds; i++) {
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leds[i] = devm_of_led_get(dev, i);
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if (IS_ERR(leds[i]))
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return PTR_ERR(leds[i]);
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}
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/* check that the LEDs all have the same brightness range */
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max_brightness = leds[0]->max_brightness;
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for (i = 1; i < nb_leds; i++) {
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if (max_brightness != leds[i]->max_brightness) {
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dev_err(dev, "LEDs must have identical ranges\n");
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return -EINVAL;
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}
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}
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/* get the default brightness from the first LED from the list */
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default_brightness = leds[0]->brightness;
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priv->nb_leds = nb_leds;
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priv->leds = leds;
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priv->max_brightness = max_brightness;
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priv->default_brightness = default_brightness;
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return 0;
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}
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static int led_bl_parse_levels(struct device *dev,
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struct led_bl_data *priv)
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{
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struct device_node *node = dev->of_node;
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int num_levels;
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u32 value;
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int ret;
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if (!node)
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return -ENODEV;
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num_levels = of_property_count_u32_elems(node, "brightness-levels");
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if (num_levels > 1) {
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int i;
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unsigned int db;
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u32 *levels = NULL;
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levels = devm_kzalloc(dev, sizeof(u32) * num_levels,
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GFP_KERNEL);
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if (!levels)
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return -ENOMEM;
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ret = of_property_read_u32_array(node, "brightness-levels",
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levels,
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num_levels);
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if (ret < 0)
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return ret;
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/*
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* Try to map actual LED brightness to backlight brightness
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* level
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*/
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db = priv->default_brightness;
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for (i = 0 ; i < num_levels; i++) {
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if ((i && db > levels[i-1]) && db <= levels[i])
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break;
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}
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priv->default_brightness = i;
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priv->max_brightness = num_levels - 1;
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priv->levels = levels;
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} else if (num_levels >= 0)
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dev_warn(dev, "Not enough levels defined\n");
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ret = of_property_read_u32(node, "default-brightness-level", &value);
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if (!ret && value <= priv->max_brightness)
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priv->default_brightness = value;
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else if (!ret && value > priv->max_brightness)
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dev_warn(dev, "Invalid default brightness. Ignoring it\n");
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return 0;
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}
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static int led_bl_probe(struct platform_device *pdev)
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{
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struct backlight_properties props;
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struct led_bl_data *priv;
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int ret, i;
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priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
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if (!priv)
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return -ENOMEM;
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platform_set_drvdata(pdev, priv);
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priv->dev = &pdev->dev;
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ret = led_bl_get_leds(&pdev->dev, priv);
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if (ret)
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return ret;
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ret = led_bl_parse_levels(&pdev->dev, priv);
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if (ret < 0) {
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dev_err(&pdev->dev, "Failed to parse DT data\n");
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return ret;
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}
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memset(&props, 0, sizeof(struct backlight_properties));
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props.type = BACKLIGHT_RAW;
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props.max_brightness = priv->max_brightness;
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props.brightness = priv->default_brightness;
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props.power = (priv->default_brightness > 0) ? FB_BLANK_POWERDOWN :
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FB_BLANK_UNBLANK;
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priv->bl_dev = backlight_device_register(dev_name(&pdev->dev),
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&pdev->dev, priv, &led_bl_ops, &props);
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if (IS_ERR(priv->bl_dev)) {
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dev_err(&pdev->dev, "Failed to register backlight\n");
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return PTR_ERR(priv->bl_dev);
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}
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for (i = 0; i < priv->nb_leds; i++)
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led_sysfs_disable(priv->leds[i]);
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backlight_update_status(priv->bl_dev);
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return 0;
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}
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static int led_bl_remove(struct platform_device *pdev)
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{
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struct led_bl_data *priv = platform_get_drvdata(pdev);
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struct backlight_device *bl = priv->bl_dev;
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int i;
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backlight_device_unregister(bl);
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led_bl_power_off(priv);
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for (i = 0; i < priv->nb_leds; i++)
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led_sysfs_enable(priv->leds[i]);
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return 0;
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}
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static const struct of_device_id led_bl_of_match[] = {
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{ .compatible = "led-backlight" },
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{ }
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};
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MODULE_DEVICE_TABLE(of, led_bl_of_match);
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static struct platform_driver led_bl_driver = {
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.driver = {
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.name = "led-backlight",
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.of_match_table = of_match_ptr(led_bl_of_match),
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},
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.probe = led_bl_probe,
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.remove = led_bl_remove,
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};
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module_platform_driver(led_bl_driver);
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MODULE_DESCRIPTION("LED based Backlight Driver");
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MODULE_LICENSE("GPL");
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MODULE_ALIAS("platform:led-backlight");
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