1 // SPDX-License-Identifier: GPL-2.0+
3 * Copyright (c) 2016 Google, Inc
4 * Written by Simon Glass <sjg@chromium.org>
7 #define LOG_CATEGORY UCLASS_PANEL_BACKLIGHT
11 #include <backlight.h>
15 #include <power/regulator.h>
18 * Private information for the PWM backlight
20 * If @num_levels is 0 then the levels are simple values with the backlight
21 * value going between the minimum (default 0) and the maximum (default 255).
22 * Otherwise the levels are an index into @levels (0..n-1).
24 * @reg: Regulator to enable to turn the backlight on (NULL if none)
25 * @enable, GPIO to set to enable the backlight (can be missing)
26 * @pwm: PWM to use to change the backlight brightness
27 * @channel: PWM channel to use
28 * @period_ns: Period of the backlight in nanoseconds
29 * @levels: Levels for the backlight, or NULL if not using indexed levels
30 * @num_levels: Number of levels
31 * @cur_level: Current level for the backlight (index or value)
32 * @default_level: Default level for the backlight (index or value)
33 * @min_level: Minimum level of the backlight (full off)
34 * @min_level: Maximum level of the backlight (full on)
35 * @enabled: true if backlight is enabled
37 struct pwm_backlight_priv {
39 struct gpio_desc enable;
44 * the polarity of one PWM
46 * 1: inverted polarity
58 static int set_pwm(struct pwm_backlight_priv *priv)
63 duty_cycle = priv->period_ns * (priv->cur_level - priv->min_level) /
64 (priv->max_level - priv->min_level + 1);
65 ret = pwm_set_config(priv->pwm, priv->channel, priv->period_ns,
70 ret = pwm_set_invert(priv->pwm, priv->channel, priv->polarity);
71 if (ret == -ENOSYS && !priv->polarity)
77 static int enable_sequence(struct udevice *dev, int seq)
79 struct pwm_backlight_priv *priv = dev_get_priv(dev);
85 __maybe_unused struct dm_regulator_uclass_platdata
88 plat = dev_get_uclass_platdata(priv->reg);
89 log_debug("Enable '%s', regulator '%s'/'%s'\n",
90 dev->name, priv->reg->name, plat->name);
91 ret = regulator_set_enable(priv->reg, true);
93 log_debug("Cannot enable regulator for PWM '%s'\n",
102 dm_gpio_set_value(&priv->enable, 1);
109 static int pwm_backlight_enable(struct udevice *dev)
111 struct pwm_backlight_priv *priv = dev_get_priv(dev);
114 ret = enable_sequence(dev, 0);
120 ret = pwm_set_enable(priv->pwm, priv->channel, true);
123 ret = enable_sequence(dev, 1);
126 priv->enabled = true;
131 static int pwm_backlight_set_brightness(struct udevice *dev, int percent)
133 struct pwm_backlight_priv *priv = dev_get_priv(dev);
134 bool disable = false;
138 if (!priv->enabled) {
139 ret = enable_sequence(dev, 0);
143 if (percent == BACKLIGHT_OFF) {
147 if (percent == BACKLIGHT_DEFAULT) {
148 level = priv->default_level;
151 level = priv->levels[percent * (priv->num_levels - 1)
154 level = priv->min_level +
155 (priv->max_level - priv->min_level) *
159 priv->cur_level = level;
164 if (!priv->enabled) {
165 ret = enable_sequence(dev, 1);
168 priv->enabled = true;
171 dm_gpio_set_value(&priv->enable, 0);
173 ret = regulator_set_enable(priv->reg, false);
177 priv->enabled = false;
183 static int pwm_backlight_ofdata_to_platdata(struct udevice *dev)
185 struct pwm_backlight_priv *priv = dev_get_priv(dev);
186 struct ofnode_phandle_args args;
187 int index, ret, count, len;
190 log_debug("start\n");
191 ret = uclass_get_device_by_phandle(UCLASS_REGULATOR, dev,
192 "power-supply", &priv->reg);
194 log_debug("Cannot get power supply: ret=%d\n", ret);
195 ret = gpio_request_by_name(dev, "enable-gpios", 0, &priv->enable,
198 log_debug("Warning: cannot get enable GPIO: ret=%d\n", ret);
202 ret = dev_read_phandle_with_args(dev, "pwms", "#pwm-cells", 0, 0,
205 log_debug("Cannot get PWM phandle: ret=%d\n", ret);
209 ret = uclass_get_device_by_ofnode(UCLASS_PWM, args.node, &priv->pwm);
211 log_debug("Cannot get PWM: ret=%d\n", ret);
214 if (args.args_count < 2)
215 return log_msg_ret("Not enough arguments to pwm\n", -EINVAL);
216 priv->channel = args.args[0];
217 priv->period_ns = args.args[1];
218 if (args.args_count > 2)
219 priv->polarity = args.args[2];
221 index = dev_read_u32_default(dev, "default-brightness-level", 255);
222 cell = dev_read_prop(dev, "brightness-levels", &len);
223 count = len / sizeof(u32);
224 if (cell && count > index) {
225 priv->levels = malloc(len);
227 return log_ret(-ENOMEM);
228 dev_read_u32_array(dev, "brightness-levels", priv->levels,
230 priv->num_levels = count;
231 priv->default_level = priv->levels[index];
232 priv->max_level = priv->levels[count - 1];
234 priv->default_level = index;
235 priv->max_level = 255;
237 priv->cur_level = priv->default_level;
244 static int pwm_backlight_probe(struct udevice *dev)
249 static const struct backlight_ops pwm_backlight_ops = {
250 .enable = pwm_backlight_enable,
251 .set_brightness = pwm_backlight_set_brightness,
254 static const struct udevice_id pwm_backlight_ids[] = {
255 { .compatible = "pwm-backlight" },
259 U_BOOT_DRIVER(pwm_backlight) = {
260 .name = "pwm_backlight",
261 .id = UCLASS_PANEL_BACKLIGHT,
262 .of_match = pwm_backlight_ids,
263 .ops = &pwm_backlight_ops,
264 .ofdata_to_platdata = pwm_backlight_ofdata_to_platdata,
265 .probe = pwm_backlight_probe,
266 .priv_auto_alloc_size = sizeof(struct pwm_backlight_priv),