1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3  * LCD-OLinuXino support for panel driver
4  *
5  * Copyright (C) 2018 Olimex Ltd.
6  *   Author: Stefan Mavrodiev <stefan@olimex.com>
7  */
8 
9 #include <linux/crc32.h>
10 #include <linux/gpio/consumer.h>
11 #include <linux/i2c.h>
12 #include <linux/module.h>
13 #include <linux/mutex.h>
14 #include <linux/of.h>
15 #include <linux/regulator/consumer.h>
16 
17 #include <video/videomode.h>
18 #include <video/display_timing.h>
19 
20 #include <drm/drm_device.h>
21 #include <drm/drm_modes.h>
22 #include <drm/drm_panel.h>
23 
24 #define LCD_OLINUXINO_HEADER_MAGIC	0x4F4CB727
25 #define LCD_OLINUXINO_DATA_LEN		256
26 
27 struct lcd_olinuxino_mode {
28 	u32 pixelclock;
29 	u32 hactive;
30 	u32 hfp;
31 	u32 hbp;
32 	u32 hpw;
33 	u32 vactive;
34 	u32 vfp;
35 	u32 vbp;
36 	u32 vpw;
37 	u32 refresh;
38 	u32 flags;
39 };
40 
41 struct lcd_olinuxino_info {
42 	char name[32];
43 	u32 width_mm;
44 	u32 height_mm;
45 	u32 bpc;
46 	u32 bus_format;
47 	u32 bus_flag;
48 } __attribute__((__packed__));
49 
50 struct lcd_olinuxino_eeprom {
51 	u32 header;
52 	u32 id;
53 	char revision[4];
54 	u32 serial;
55 	struct lcd_olinuxino_info info;
56 	u32 num_modes;
57 	u8 reserved[180];
58 	u32 checksum;
59 } __attribute__((__packed__));
60 
61 struct lcd_olinuxino {
62 	struct drm_panel panel;
63 	struct device *dev;
64 	struct i2c_client *client;
65 	struct mutex mutex;
66 
67 	bool prepared;
68 	bool enabled;
69 
70 	struct regulator *supply;
71 	struct gpio_desc *enable_gpio;
72 
73 	struct lcd_olinuxino_eeprom eeprom;
74 };
75 
76 static inline struct lcd_olinuxino *to_lcd_olinuxino(struct drm_panel *panel)
77 {
78 	return container_of(panel, struct lcd_olinuxino, panel);
79 }
80 
81 static int lcd_olinuxino_disable(struct drm_panel *panel)
82 {
83 	struct lcd_olinuxino *lcd = to_lcd_olinuxino(panel);
84 
85 	if (!lcd->enabled)
86 		return 0;
87 
88 	lcd->enabled = false;
89 
90 	return 0;
91 }
92 
93 static int lcd_olinuxino_unprepare(struct drm_panel *panel)
94 {
95 	struct lcd_olinuxino *lcd = to_lcd_olinuxino(panel);
96 
97 	if (!lcd->prepared)
98 		return 0;
99 
100 	gpiod_set_value_cansleep(lcd->enable_gpio, 0);
101 	regulator_disable(lcd->supply);
102 
103 	lcd->prepared = false;
104 
105 	return 0;
106 }
107 
108 static int lcd_olinuxino_prepare(struct drm_panel *panel)
109 {
110 	struct lcd_olinuxino *lcd = to_lcd_olinuxino(panel);
111 	int ret;
112 
113 	if (lcd->prepared)
114 		return 0;
115 
116 	ret = regulator_enable(lcd->supply);
117 	if (ret < 0)
118 		return ret;
119 
120 	gpiod_set_value_cansleep(lcd->enable_gpio, 1);
121 	lcd->prepared = true;
122 
123 	return 0;
124 }
125 
126 static int lcd_olinuxino_enable(struct drm_panel *panel)
127 {
128 	struct lcd_olinuxino *lcd = to_lcd_olinuxino(panel);
129 
130 	if (lcd->enabled)
131 		return 0;
132 
133 	lcd->enabled = true;
134 
135 	return 0;
136 }
137 
138 static int lcd_olinuxino_get_modes(struct drm_panel *panel,
139 				   struct drm_connector *connector)
140 {
141 	struct lcd_olinuxino *lcd = to_lcd_olinuxino(panel);
142 	struct lcd_olinuxino_info *lcd_info = &lcd->eeprom.info;
143 	struct lcd_olinuxino_mode *lcd_mode;
144 	struct drm_display_mode *mode;
145 	u32 i, num = 0;
146 
147 	for (i = 0; i < lcd->eeprom.num_modes; i++) {
148 		lcd_mode = (struct lcd_olinuxino_mode *)
149 			   &lcd->eeprom.reserved[i * sizeof(*lcd_mode)];
150 
151 		mode = drm_mode_create(connector->dev);
152 		if (!mode) {
153 			dev_err(panel->dev, "failed to add mode %ux%u@%u\n",
154 				lcd_mode->hactive,
155 				lcd_mode->vactive,
156 				lcd_mode->refresh);
157 			continue;
158 		}
159 
160 		mode->clock = lcd_mode->pixelclock;
161 		mode->hdisplay = lcd_mode->hactive;
162 		mode->hsync_start = lcd_mode->hactive + lcd_mode->hfp;
163 		mode->hsync_end = lcd_mode->hactive + lcd_mode->hfp +
164 				  lcd_mode->hpw;
165 		mode->htotal = lcd_mode->hactive + lcd_mode->hfp +
166 			       lcd_mode->hpw + lcd_mode->hbp;
167 		mode->vdisplay = lcd_mode->vactive;
168 		mode->vsync_start = lcd_mode->vactive + lcd_mode->vfp;
169 		mode->vsync_end = lcd_mode->vactive + lcd_mode->vfp +
170 				  lcd_mode->vpw;
171 		mode->vtotal = lcd_mode->vactive + lcd_mode->vfp +
172 			       lcd_mode->vpw + lcd_mode->vbp;
173 
174 		/* Always make the first mode preferred */
175 		if (i == 0)
176 			mode->type |= DRM_MODE_TYPE_PREFERRED;
177 		mode->type |= DRM_MODE_TYPE_DRIVER;
178 
179 		drm_mode_set_name(mode);
180 		drm_mode_probed_add(connector, mode);
181 
182 		num++;
183 	}
184 
185 	connector->display_info.width_mm = lcd_info->width_mm;
186 	connector->display_info.height_mm = lcd_info->height_mm;
187 	connector->display_info.bpc = lcd_info->bpc;
188 
189 	if (lcd_info->bus_format)
190 		drm_display_info_set_bus_formats(&connector->display_info,
191 						 &lcd_info->bus_format, 1);
192 	connector->display_info.bus_flags = lcd_info->bus_flag;
193 
194 	return num;
195 }
196 
197 static const struct drm_panel_funcs lcd_olinuxino_funcs = {
198 	.disable = lcd_olinuxino_disable,
199 	.unprepare = lcd_olinuxino_unprepare,
200 	.prepare = lcd_olinuxino_prepare,
201 	.enable = lcd_olinuxino_enable,
202 	.get_modes = lcd_olinuxino_get_modes,
203 };
204 
205 static int lcd_olinuxino_probe(struct i2c_client *client,
206 			       const struct i2c_device_id *id)
207 {
208 	struct device *dev = &client->dev;
209 	struct lcd_olinuxino *lcd;
210 	u32 checksum, i;
211 	int ret = 0;
212 
213 	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C |
214 				     I2C_FUNC_SMBUS_READ_I2C_BLOCK))
215 		return -ENODEV;
216 
217 	lcd = devm_kzalloc(dev, sizeof(*lcd), GFP_KERNEL);
218 	if (!lcd)
219 		return -ENOMEM;
220 
221 	i2c_set_clientdata(client, lcd);
222 	lcd->dev = dev;
223 	lcd->client = client;
224 
225 	mutex_init(&lcd->mutex);
226 
227 	/* Copy data into buffer */
228 	for (i = 0; i < LCD_OLINUXINO_DATA_LEN; i += I2C_SMBUS_BLOCK_MAX) {
229 		mutex_lock(&lcd->mutex);
230 		ret = i2c_smbus_read_i2c_block_data(client,
231 						    i,
232 						    I2C_SMBUS_BLOCK_MAX,
233 						    (u8 *)&lcd->eeprom + i);
234 		mutex_unlock(&lcd->mutex);
235 		if (ret < 0) {
236 			dev_err(dev, "error reading from device at %02x\n", i);
237 			return ret;
238 		}
239 	}
240 
241 	/* Check configuration checksum */
242 	checksum = ~crc32(~0, (u8 *)&lcd->eeprom, 252);
243 	if (checksum != lcd->eeprom.checksum) {
244 		dev_err(dev, "configuration checksum does not match!\n");
245 		return -EINVAL;
246 	}
247 
248 	/* Check magic header */
249 	if (lcd->eeprom.header != LCD_OLINUXINO_HEADER_MAGIC) {
250 		dev_err(dev, "magic header does not match\n");
251 		return -EINVAL;
252 	}
253 
254 	dev_info(dev, "Detected %s, Rev. %s, Serial: %08x\n",
255 		 lcd->eeprom.info.name,
256 		 lcd->eeprom.revision,
257 		 lcd->eeprom.serial);
258 
259 	/*
260 	 * The eeprom can hold up to 4 modes.
261 	 * If the stored value is bigger, overwrite it.
262 	 */
263 	if (lcd->eeprom.num_modes > 4) {
264 		dev_warn(dev, "invalid number of modes, falling back to 4\n");
265 		lcd->eeprom.num_modes = 4;
266 	}
267 
268 	lcd->enabled = false;
269 	lcd->prepared = false;
270 
271 	lcd->supply = devm_regulator_get(dev, "power");
272 	if (IS_ERR(lcd->supply))
273 		return PTR_ERR(lcd->supply);
274 
275 	lcd->enable_gpio = devm_gpiod_get(dev, "enable", GPIOD_OUT_LOW);
276 	if (IS_ERR(lcd->enable_gpio))
277 		return PTR_ERR(lcd->enable_gpio);
278 
279 	drm_panel_init(&lcd->panel, dev, &lcd_olinuxino_funcs,
280 		       DRM_MODE_CONNECTOR_DPI);
281 
282 	ret = drm_panel_of_backlight(&lcd->panel);
283 	if (ret)
284 		return ret;
285 
286 	drm_panel_add(&lcd->panel);
287 
288 	return 0;
289 }
290 
291 static int lcd_olinuxino_remove(struct i2c_client *client)
292 {
293 	struct lcd_olinuxino *panel = i2c_get_clientdata(client);
294 
295 	drm_panel_remove(&panel->panel);
296 
297 	drm_panel_disable(&panel->panel);
298 	drm_panel_unprepare(&panel->panel);
299 
300 	return 0;
301 }
302 
303 static const struct of_device_id lcd_olinuxino_of_ids[] = {
304 	{ .compatible = "olimex,lcd-olinuxino" },
305 	{ }
306 };
307 MODULE_DEVICE_TABLE(of, lcd_olinuxino_of_ids);
308 
309 static struct i2c_driver lcd_olinuxino_driver = {
310 	.driver = {
311 		.name = "lcd_olinuxino",
312 		.of_match_table = lcd_olinuxino_of_ids,
313 	},
314 	.probe = lcd_olinuxino_probe,
315 	.remove = lcd_olinuxino_remove,
316 };
317 
318 module_i2c_driver(lcd_olinuxino_driver);
319 
320 MODULE_AUTHOR("Stefan Mavrodiev <stefan@olimex.com>");
321 MODULE_DESCRIPTION("LCD-OLinuXino driver");
322 MODULE_LICENSE("GPL");
323