1 // SPDX-License-Identifier: GPL-2.0
3 * Copyright (C) 2015-2019 Texas Instruments Incorporated - http://www.ti.com/
4 * Author: Tomi Valkeinen <tomi.valkeinen@ti.com>
9 #include <linux/backlight.h>
10 #include <linux/leds.h>
11 #include <linux/module.h>
12 #include <linux/platform_device.h>
16 struct backlight_device *bl_dev;
17 struct led_classdev **leds;
21 unsigned int default_brightness;
22 unsigned int max_brightness;
25 static void led_bl_set_brightness(struct led_bl_data *priv, int level)
31 bkl_brightness = priv->levels[level];
33 bkl_brightness = level;
35 for (i = 0; i < priv->nb_leds; i++)
36 led_set_brightness(priv->leds[i], bkl_brightness);
41 static void led_bl_power_off(struct led_bl_data *priv)
48 for (i = 0; i < priv->nb_leds; i++)
49 led_set_brightness(priv->leds[i], LED_OFF);
51 priv->enabled = false;
54 static int led_bl_update_status(struct backlight_device *bl)
56 struct led_bl_data *priv = bl_get_data(bl);
57 int brightness = bl->props.brightness;
59 if (bl->props.power != FB_BLANK_UNBLANK ||
60 bl->props.fb_blank != FB_BLANK_UNBLANK ||
61 bl->props.state & BL_CORE_FBBLANK)
65 led_bl_set_brightness(priv, brightness);
67 led_bl_power_off(priv);
72 static const struct backlight_ops led_bl_ops = {
73 .update_status = led_bl_update_status,
76 static int led_bl_get_leds(struct device *dev,
77 struct led_bl_data *priv)
80 struct device_node *node = dev->of_node;
81 struct led_classdev **leds;
82 unsigned int max_brightness;
83 unsigned int default_brightness;
85 ret = of_count_phandle_with_args(node, "leds", NULL);
87 dev_err(dev, "Unable to get led count\n");
93 dev_err(dev, "At least one LED must be specified!\n");
97 leds = devm_kzalloc(dev, sizeof(struct led_classdev *) * nb_leds,
102 for (i = 0; i < nb_leds; i++) {
103 leds[i] = devm_of_led_get(dev, i);
105 return PTR_ERR(leds[i]);
108 /* check that the LEDs all have the same brightness range */
109 max_brightness = leds[0]->max_brightness;
110 for (i = 1; i < nb_leds; i++) {
111 if (max_brightness != leds[i]->max_brightness) {
112 dev_err(dev, "LEDs must have identical ranges\n");
117 /* get the default brightness from the first LED from the list */
118 default_brightness = leds[0]->brightness;
120 priv->nb_leds = nb_leds;
122 priv->max_brightness = max_brightness;
123 priv->default_brightness = default_brightness;
128 static int led_bl_parse_levels(struct device *dev,
129 struct led_bl_data *priv)
131 struct device_node *node = dev->of_node;
139 num_levels = of_property_count_u32_elems(node, "brightness-levels");
140 if (num_levels > 1) {
145 levels = devm_kzalloc(dev, sizeof(u32) * num_levels,
150 ret = of_property_read_u32_array(node, "brightness-levels",
157 * Try to map actual LED brightness to backlight brightness
160 db = priv->default_brightness;
161 for (i = 0 ; i < num_levels; i++) {
162 if ((i && db > levels[i-1]) && db <= levels[i])
165 priv->default_brightness = i;
166 priv->max_brightness = num_levels - 1;
167 priv->levels = levels;
168 } else if (num_levels >= 0)
169 dev_warn(dev, "Not enough levels defined\n");
171 ret = of_property_read_u32(node, "default-brightness-level", &value);
172 if (!ret && value <= priv->max_brightness)
173 priv->default_brightness = value;
174 else if (!ret && value > priv->max_brightness)
175 dev_warn(dev, "Invalid default brightness. Ignoring it\n");
180 static int led_bl_probe(struct platform_device *pdev)
182 struct backlight_properties props;
183 struct led_bl_data *priv;
186 priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
190 platform_set_drvdata(pdev, priv);
192 priv->dev = &pdev->dev;
194 ret = led_bl_get_leds(&pdev->dev, priv);
198 ret = led_bl_parse_levels(&pdev->dev, priv);
200 dev_err(&pdev->dev, "Failed to parse DT data\n");
204 memset(&props, 0, sizeof(struct backlight_properties));
205 props.type = BACKLIGHT_RAW;
206 props.max_brightness = priv->max_brightness;
207 props.brightness = priv->default_brightness;
208 props.power = (priv->default_brightness > 0) ? FB_BLANK_POWERDOWN :
210 priv->bl_dev = backlight_device_register(dev_name(&pdev->dev),
211 &pdev->dev, priv, &led_bl_ops, &props);
212 if (IS_ERR(priv->bl_dev)) {
213 dev_err(&pdev->dev, "Failed to register backlight\n");
214 return PTR_ERR(priv->bl_dev);
217 for (i = 0; i < priv->nb_leds; i++)
218 led_sysfs_disable(priv->leds[i]);
220 backlight_update_status(priv->bl_dev);
225 static int led_bl_remove(struct platform_device *pdev)
227 struct led_bl_data *priv = platform_get_drvdata(pdev);
228 struct backlight_device *bl = priv->bl_dev;
231 backlight_device_unregister(bl);
233 led_bl_power_off(priv);
234 for (i = 0; i < priv->nb_leds; i++)
235 led_sysfs_enable(priv->leds[i]);
240 static const struct of_device_id led_bl_of_match[] = {
241 { .compatible = "led-backlight" },
245 MODULE_DEVICE_TABLE(of, led_bl_of_match);
247 static struct platform_driver led_bl_driver = {
249 .name = "led-backlight",
250 .of_match_table = of_match_ptr(led_bl_of_match),
252 .probe = led_bl_probe,
253 .remove = led_bl_remove,
256 module_platform_driver(led_bl_driver);
258 MODULE_DESCRIPTION("LED based Backlight Driver");
259 MODULE_LICENSE("GPL");
260 MODULE_ALIAS("platform:led-backlight");