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>
14 #include <power/regulator.h>
17 * Private information for the PWM backlight
19 * If @num_levels is 0 then the levels are simple values with the backlight
20 * value going between the minimum (default 0) and the maximum (default 255).
21 * Otherwise the levels are an index into @levels (0..n-1).
23 * @reg: Regulator to enable to turn the backlight on (NULL if none)
24 * @enable, GPIO to set to enable the backlight (can be missing)
25 * @pwm: PWM to use to change the backlight brightness
26 * @channel: PWM channel to use
27 * @period_ns: Period of the backlight in nanoseconds
28 * @levels: Levels for the backlight, or NULL if not using indexed levels
29 * @num_levels: Number of levels
30 * @cur_level: Current level for the backlight (index or value)
31 * @default_level: Default level for the backlight (index or value)
32 * @min_level: Minimum level of the backlight (full off)
33 * @min_level: Maximum level of the backlight (full on)
34 * @enabled: true if backlight is enabled
36 struct pwm_backlight_priv
{
38 struct gpio_desc enable
;
43 * the polarity of one PWM
45 * 1: inverted polarity
57 static int set_pwm(struct pwm_backlight_priv
*priv
)
62 duty_cycle
= priv
->period_ns
* (priv
->cur_level
- priv
->min_level
) /
63 (priv
->max_level
- priv
->min_level
+ 1);
64 ret
= pwm_set_config(priv
->pwm
, priv
->channel
, priv
->period_ns
,
69 ret
= pwm_set_invert(priv
->pwm
, priv
->channel
, priv
->polarity
);
70 if (ret
== -ENOSYS
&& !priv
->polarity
)
76 static int enable_sequence(struct udevice
*dev
, int seq
)
78 struct pwm_backlight_priv
*priv
= dev_get_priv(dev
);
84 __maybe_unused
struct dm_regulator_uclass_platdata
87 plat
= dev_get_uclass_platdata(priv
->reg
);
88 log_debug("Enable '%s', regulator '%s'/'%s'\n",
89 dev
->name
, priv
->reg
->name
, plat
->name
);
90 ret
= regulator_set_enable(priv
->reg
, true);
92 log_debug("Cannot enable regulator for PWM '%s'\n",
101 dm_gpio_set_value(&priv
->enable
, 1);
108 static int pwm_backlight_enable(struct udevice
*dev
)
110 struct pwm_backlight_priv
*priv
= dev_get_priv(dev
);
113 ret
= enable_sequence(dev
, 0);
119 ret
= pwm_set_enable(priv
->pwm
, priv
->channel
, true);
122 ret
= enable_sequence(dev
, 1);
125 priv
->enabled
= true;
130 static int pwm_backlight_set_brightness(struct udevice
*dev
, int percent
)
132 struct pwm_backlight_priv
*priv
= dev_get_priv(dev
);
133 bool disable
= false;
137 if (!priv
->enabled
) {
138 ret
= enable_sequence(dev
, 0);
142 if (percent
== BACKLIGHT_OFF
) {
146 if (percent
== BACKLIGHT_DEFAULT
) {
147 level
= priv
->default_level
;
150 level
= priv
->levels
[percent
* (priv
->num_levels
- 1)
153 level
= priv
->min_level
+
154 (priv
->max_level
- priv
->min_level
) *
158 priv
->cur_level
= level
;
163 if (!priv
->enabled
) {
164 ret
= enable_sequence(dev
, 1);
167 priv
->enabled
= true;
170 dm_gpio_set_value(&priv
->enable
, 0);
172 ret
= regulator_set_enable(priv
->reg
, false);
176 priv
->enabled
= false;
182 static int pwm_backlight_ofdata_to_platdata(struct udevice
*dev
)
184 struct pwm_backlight_priv
*priv
= dev_get_priv(dev
);
185 struct ofnode_phandle_args args
;
186 int index
, ret
, count
, len
;
189 log_debug("start\n");
190 ret
= uclass_get_device_by_phandle(UCLASS_REGULATOR
, dev
,
191 "power-supply", &priv
->reg
);
193 log_debug("Cannot get power supply: ret=%d\n", ret
);
194 ret
= gpio_request_by_name(dev
, "enable-gpios", 0, &priv
->enable
,
197 log_debug("Warning: cannot get enable GPIO: ret=%d\n", ret
);
201 ret
= dev_read_phandle_with_args(dev
, "pwms", "#pwm-cells", 0, 0,
204 log_debug("Cannot get PWM phandle: ret=%d\n", ret
);
208 ret
= uclass_get_device_by_ofnode(UCLASS_PWM
, args
.node
, &priv
->pwm
);
210 log_debug("Cannot get PWM: ret=%d\n", ret
);
213 if (args
.args_count
< 2)
214 return log_msg_ret("Not enough arguments to pwm\n", -EINVAL
);
215 priv
->channel
= args
.args
[0];
216 priv
->period_ns
= args
.args
[1];
217 if (args
.args_count
> 2)
218 priv
->polarity
= args
.args
[2];
220 index
= dev_read_u32_default(dev
, "default-brightness-level", 255);
221 cell
= dev_read_prop(dev
, "brightness-levels", &len
);
222 count
= len
/ sizeof(u32
);
223 if (cell
&& count
> index
) {
224 priv
->levels
= malloc(len
);
226 return log_ret(-ENOMEM
);
227 dev_read_u32_array(dev
, "brightness-levels", priv
->levels
,
229 priv
->num_levels
= count
;
230 priv
->default_level
= priv
->levels
[index
];
231 priv
->max_level
= priv
->levels
[count
- 1];
233 priv
->default_level
= index
;
234 priv
->max_level
= 255;
236 priv
->cur_level
= priv
->default_level
;
243 static int pwm_backlight_probe(struct udevice
*dev
)
248 static const struct backlight_ops pwm_backlight_ops
= {
249 .enable
= pwm_backlight_enable
,
250 .set_brightness
= pwm_backlight_set_brightness
,
253 static const struct udevice_id pwm_backlight_ids
[] = {
254 { .compatible
= "pwm-backlight" },
258 U_BOOT_DRIVER(pwm_backlight
) = {
259 .name
= "pwm_backlight",
260 .id
= UCLASS_PANEL_BACKLIGHT
,
261 .of_match
= pwm_backlight_ids
,
262 .ops
= &pwm_backlight_ops
,
263 .ofdata_to_platdata
= pwm_backlight_ofdata_to_platdata
,
264 .probe
= pwm_backlight_probe
,
265 .priv_auto_alloc_size
= sizeof(struct pwm_backlight_priv
),