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 	u32 *levels;
43 	int num_levels;
44 	uint default_level;
45 	int cur_level;
46 	uint min_level;
47 	uint max_level;
48 	bool enabled;
49 };
50 
51 static int set_pwm(struct pwm_backlight_priv *priv)
52 {
53 	uint duty_cycle;
54 	int ret;
55 
56 	duty_cycle = priv->period_ns * (priv->cur_level - priv->min_level) /
57 		(priv->max_level - priv->min_level + 1);
58 	ret = pwm_set_config(priv->pwm, priv->channel, priv->period_ns,
59 			     duty_cycle);
60 
61 	return log_ret(ret);
62 }
63 
64 static int enable_sequence(struct udevice *dev, int seq)
65 {
66 	struct pwm_backlight_priv *priv = dev_get_priv(dev);
67 	int ret;
68 
69 	switch (seq) {
70 	case 0:
71 		if (priv->reg) {
72 			__maybe_unused struct dm_regulator_uclass_platdata
73 				*plat;
74 
75 			plat = dev_get_uclass_platdata(priv->reg);
76 			log_debug("Enable '%s', regulator '%s'/'%s'\n",
77 				  dev->name, priv->reg->name, plat->name);
78 			ret = regulator_set_enable(priv->reg, true);
79 			if (ret) {
80 				log_debug("Cannot enable regulator for PWM '%s'\n",
81 					  __func__, dev->name);
82 				return log_ret(ret);
83 			}
84 			mdelay(120);
85 		}
86 		break;
87 	case 1:
88 		mdelay(10);
89 		dm_gpio_set_value(&priv->enable, 1);
90 		break;
91 	}
92 
93 	return 0;
94 }
95 
96 static int pwm_backlight_enable(struct udevice *dev)
97 {
98 	struct pwm_backlight_priv *priv = dev_get_priv(dev);
99 	int ret;
100 
101 	ret = enable_sequence(dev, 0);
102 	if (ret)
103 		return log_ret(ret);
104 	ret = set_pwm(priv);
105 	if (ret)
106 		return log_ret(ret);
107 	ret = pwm_set_enable(priv->pwm, priv->channel, true);
108 	if (ret)
109 		return log_ret(ret);
110 	ret = enable_sequence(dev, 1);
111 	if (ret)
112 		return log_ret(ret);
113 	priv->enabled = true;
114 
115 	return 0;
116 }
117 
118 static int pwm_backlight_set_brightness(struct udevice *dev, int percent)
119 {
120 	struct pwm_backlight_priv *priv = dev_get_priv(dev);
121 	bool disable = false;
122 	int level;
123 	int ret;
124 
125 	if (!priv->enabled) {
126 		ret = enable_sequence(dev, 0);
127 		if (ret)
128 			return log_ret(ret);
129 	}
130 	if (percent == BACKLIGHT_OFF) {
131 		disable = true;
132 		percent = 0;
133 	}
134 	if (percent == BACKLIGHT_DEFAULT) {
135 		level = priv->default_level;
136 	} else {
137 		if (priv->levels) {
138 			level = priv->levels[percent * (priv->num_levels - 1)
139 				/ 100];
140 		} else {
141 			level = priv->min_level +
142 				(priv->max_level - priv->min_level) *
143 				percent / 100;
144 		}
145 	}
146 	priv->cur_level = level;
147 
148 	ret = set_pwm(priv);
149 	if (ret)
150 		return log_ret(ret);
151 	if (!priv->enabled) {
152 		ret = enable_sequence(dev, 1);
153 		if (ret)
154 			return log_ret(ret);
155 		priv->enabled = true;
156 	}
157 	if (disable) {
158 		dm_gpio_set_value(&priv->enable, 0);
159 		if (priv->reg) {
160 			ret = regulator_set_enable(priv->reg, false);
161 			if (ret)
162 				return log_ret(ret);
163 		}
164 		priv->enabled = false;
165 	}
166 
167 	return 0;
168 }
169 
170 static int pwm_backlight_ofdata_to_platdata(struct udevice *dev)
171 {
172 	struct pwm_backlight_priv *priv = dev_get_priv(dev);
173 	struct ofnode_phandle_args args;
174 	int index, ret, count, len;
175 	const u32 *cell;
176 
177 	log_debug("start\n");
178 	ret = uclass_get_device_by_phandle(UCLASS_REGULATOR, dev,
179 					   "power-supply", &priv->reg);
180 	if (ret)
181 		log_debug("Cannot get power supply: ret=%d\n", ret);
182 	ret = gpio_request_by_name(dev, "enable-gpios", 0, &priv->enable,
183 				   GPIOD_IS_OUT);
184 	if (ret) {
185 		log_debug("Warning: cannot get enable GPIO: ret=%d\n", ret);
186 		if (ret != -ENOENT)
187 			return log_ret(ret);
188 	}
189 	ret = dev_read_phandle_with_args(dev, "pwms", "#pwm-cells", 0, 0,
190 					 &args);
191 	if (ret) {
192 		log_debug("Cannot get PWM phandle: ret=%d\n", ret);
193 		return log_ret(ret);
194 	}
195 
196 	ret = uclass_get_device_by_ofnode(UCLASS_PWM, args.node, &priv->pwm);
197 	if (ret) {
198 		log_debug("Cannot get PWM: ret=%d\n", ret);
199 		return log_ret(ret);
200 	}
201 	if (args.args_count < 2)
202 		return log_msg_ret("Not enough arguments to pwm\n", -EINVAL);
203 	priv->channel = args.args[0];
204 	priv->period_ns = args.args[1];
205 
206 	index = dev_read_u32_default(dev, "default-brightness-level", 255);
207 	cell = dev_read_prop(dev, "brightness-levels", &len);
208 	count = len / sizeof(u32);
209 	if (cell && count > index) {
210 		priv->levels = malloc(len);
211 		if (!priv->levels)
212 			return log_ret(-ENOMEM);
213 		dev_read_u32_array(dev, "brightness-levels", priv->levels,
214 				   count);
215 		priv->num_levels = count;
216 		priv->default_level = priv->levels[index];
217 		priv->max_level = priv->levels[count - 1];
218 	} else {
219 		priv->default_level = index;
220 		priv->max_level = 255;
221 	}
222 	priv->cur_level = priv->default_level;
223 	log_debug("done\n");
224 
225 
226 	return 0;
227 }
228 
229 static int pwm_backlight_probe(struct udevice *dev)
230 {
231 	return 0;
232 }
233 
234 static const struct backlight_ops pwm_backlight_ops = {
235 	.enable		= pwm_backlight_enable,
236 	.set_brightness	= pwm_backlight_set_brightness,
237 };
238 
239 static const struct udevice_id pwm_backlight_ids[] = {
240 	{ .compatible = "pwm-backlight" },
241 	{ }
242 };
243 
244 U_BOOT_DRIVER(pwm_backlight) = {
245 	.name	= "pwm_backlight",
246 	.id	= UCLASS_PANEL_BACKLIGHT,
247 	.of_match = pwm_backlight_ids,
248 	.ops	= &pwm_backlight_ops,
249 	.ofdata_to_platdata	= pwm_backlight_ofdata_to_platdata,
250 	.probe		= pwm_backlight_probe,
251 	.priv_auto_alloc_size	= sizeof(struct pwm_backlight_priv),
252 };
253