1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3 * Copyright (c) 2016 Google, Inc
4 * Written by Simon Glass <sjg@chromium.org>
5 */
6
7 #define LOG_CATEGORY UCLASS_PANEL_BACKLIGHT
8
9 #include <common.h>
10 #include <dm.h>
11 #include <backlight.h>
12 #include <pwm.h>
13 #include <asm/gpio.h>
14 #include <power/regulator.h>
15
16 /**
17 * Private information for the PWM backlight
18 *
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).
22 *
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
35 */
36 struct pwm_backlight_priv {
37 struct udevice *reg;
38 struct gpio_desc enable;
39 struct udevice *pwm;
40 uint channel;
41 uint period_ns;
42 /*
43 * the polarity of one PWM
44 * 0: normal polarity
45 * 1: inverted polarity
46 */
47 bool polarity;
48 u32 *levels;
49 int num_levels;
50 uint default_level;
51 int cur_level;
52 uint min_level;
53 uint max_level;
54 bool enabled;
55 };
56
set_pwm(struct pwm_backlight_priv * priv)57 static int set_pwm(struct pwm_backlight_priv *priv)
58 {
59 uint duty_cycle;
60 int ret;
61
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,
65 duty_cycle);
66 if (ret)
67 return log_ret(ret);
68
69 ret = pwm_set_invert(priv->pwm, priv->channel, priv->polarity);
70 if (ret == -ENOSYS && !priv->polarity)
71 ret = 0;
72
73 return log_ret(ret);
74 }
75
enable_sequence(struct udevice * dev,int seq)76 static int enable_sequence(struct udevice *dev, int seq)
77 {
78 struct pwm_backlight_priv *priv = dev_get_priv(dev);
79 int ret;
80
81 switch (seq) {
82 case 0:
83 if (priv->reg) {
84 __maybe_unused struct dm_regulator_uclass_platdata
85 *plat;
86
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);
91 if (ret) {
92 log_debug("Cannot enable regulator for PWM '%s'\n",
93 dev->name);
94 return log_ret(ret);
95 }
96 mdelay(120);
97 }
98 break;
99 case 1:
100 mdelay(10);
101 dm_gpio_set_value(&priv->enable, 1);
102 break;
103 }
104
105 return 0;
106 }
107
pwm_backlight_enable(struct udevice * dev)108 static int pwm_backlight_enable(struct udevice *dev)
109 {
110 struct pwm_backlight_priv *priv = dev_get_priv(dev);
111 int ret;
112
113 ret = enable_sequence(dev, 0);
114 if (ret)
115 return log_ret(ret);
116 ret = set_pwm(priv);
117 if (ret)
118 return log_ret(ret);
119 ret = pwm_set_enable(priv->pwm, priv->channel, true);
120 if (ret)
121 return log_ret(ret);
122 ret = enable_sequence(dev, 1);
123 if (ret)
124 return log_ret(ret);
125 priv->enabled = true;
126
127 return 0;
128 }
129
pwm_backlight_set_brightness(struct udevice * dev,int percent)130 static int pwm_backlight_set_brightness(struct udevice *dev, int percent)
131 {
132 struct pwm_backlight_priv *priv = dev_get_priv(dev);
133 bool disable = false;
134 int level;
135 int ret;
136
137 if (!priv->enabled) {
138 ret = enable_sequence(dev, 0);
139 if (ret)
140 return log_ret(ret);
141 }
142 if (percent == BACKLIGHT_OFF) {
143 disable = true;
144 percent = 0;
145 }
146 if (percent == BACKLIGHT_DEFAULT) {
147 level = priv->default_level;
148 } else {
149 if (priv->levels) {
150 level = priv->levels[percent * (priv->num_levels - 1)
151 / 100];
152 } else {
153 level = priv->min_level +
154 (priv->max_level - priv->min_level) *
155 percent / 100;
156 }
157 }
158 priv->cur_level = level;
159
160 ret = set_pwm(priv);
161 if (ret)
162 return log_ret(ret);
163 if (!priv->enabled) {
164 ret = enable_sequence(dev, 1);
165 if (ret)
166 return log_ret(ret);
167 priv->enabled = true;
168 }
169 if (disable) {
170 dm_gpio_set_value(&priv->enable, 0);
171 if (priv->reg) {
172 ret = regulator_set_enable(priv->reg, false);
173 if (ret)
174 return log_ret(ret);
175 }
176 priv->enabled = false;
177 }
178
179 return 0;
180 }
181
pwm_backlight_ofdata_to_platdata(struct udevice * dev)182 static int pwm_backlight_ofdata_to_platdata(struct udevice *dev)
183 {
184 struct pwm_backlight_priv *priv = dev_get_priv(dev);
185 struct ofnode_phandle_args args;
186 int index, ret, count, len;
187 const u32 *cell;
188
189 log_debug("start\n");
190 ret = uclass_get_device_by_phandle(UCLASS_REGULATOR, dev,
191 "power-supply", &priv->reg);
192 if (ret)
193 log_debug("Cannot get power supply: ret=%d\n", ret);
194 ret = gpio_request_by_name(dev, "enable-gpios", 0, &priv->enable,
195 GPIOD_IS_OUT);
196 if (ret) {
197 log_debug("Warning: cannot get enable GPIO: ret=%d\n", ret);
198 if (ret != -ENOENT)
199 return log_ret(ret);
200 }
201 ret = dev_read_phandle_with_args(dev, "pwms", "#pwm-cells", 0, 0,
202 &args);
203 if (ret) {
204 log_debug("Cannot get PWM phandle: ret=%d\n", ret);
205 return log_ret(ret);
206 }
207
208 ret = uclass_get_device_by_ofnode(UCLASS_PWM, args.node, &priv->pwm);
209 if (ret) {
210 log_debug("Cannot get PWM: ret=%d\n", ret);
211 return log_ret(ret);
212 }
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];
219
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);
225 if (!priv->levels)
226 return log_ret(-ENOMEM);
227 dev_read_u32_array(dev, "brightness-levels", priv->levels,
228 count);
229 priv->num_levels = count;
230 priv->default_level = priv->levels[index];
231 priv->max_level = priv->levels[count - 1];
232 } else {
233 priv->default_level = index;
234 priv->max_level = 255;
235 }
236 priv->cur_level = priv->default_level;
237 log_debug("done\n");
238
239
240 return 0;
241 }
242
pwm_backlight_probe(struct udevice * dev)243 static int pwm_backlight_probe(struct udevice *dev)
244 {
245 return 0;
246 }
247
248 static const struct backlight_ops pwm_backlight_ops = {
249 .enable = pwm_backlight_enable,
250 .set_brightness = pwm_backlight_set_brightness,
251 };
252
253 static const struct udevice_id pwm_backlight_ids[] = {
254 { .compatible = "pwm-backlight" },
255 { }
256 };
257
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),
266 };
267