1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * Panel driver for the TPO TPG110 400CH LTPS TFT LCD Single Chip
4  * Digital Driver.
5  *
6  * This chip drives a TFT LCD, so it does not know what kind of
7  * display is actually connected to it, so the width and height of that
8  * display needs to be supplied from the machine configuration.
9  *
10  * Author:
11  * Linus Walleij <linus.walleij@linaro.org>
12  */
13 #include <drm/drm_modes.h>
14 #include <drm/drm_panel.h>
15 
16 #include <linux/bitops.h>
17 #include <linux/delay.h>
18 #include <linux/gpio/consumer.h>
19 #include <linux/init.h>
20 #include <linux/kernel.h>
21 #include <linux/module.h>
22 #include <linux/of.h>
23 #include <linux/platform_device.h>
24 #include <linux/spi/spi.h>
25 
26 #define TPG110_TEST			0x00
27 #define TPG110_CHIPID			0x01
28 #define TPG110_CTRL1			0x02
29 #define TPG110_RES_MASK			GENMASK(2, 0)
30 #define TPG110_RES_800X480		0x07
31 #define TPG110_RES_640X480		0x06
32 #define TPG110_RES_480X272		0x05
33 #define TPG110_RES_480X640		0x04
34 #define TPG110_RES_480X272_D		0x01 /* Dual scan: outputs 800x480 */
35 #define TPG110_RES_400X240_D		0x00 /* Dual scan: outputs 800x480 */
36 #define TPG110_CTRL2			0x03
37 #define TPG110_CTRL2_PM			BIT(0)
38 #define TPG110_CTRL2_RES_PM_CTRL	BIT(7)
39 
40 /**
41  * struct tpg110_panel_mode - lookup struct for the supported modes
42  */
43 struct tpg110_panel_mode {
44 	/**
45 	 * @name: the name of this panel
46 	 */
47 	const char *name;
48 	/**
49 	 * @magic: the magic value from the detection register
50 	 */
51 	u32 magic;
52 	/**
53 	 * @mode: the DRM display mode for this panel
54 	 */
55 	struct drm_display_mode mode;
56 	/**
57 	 * @bus_flags: the DRM bus flags for this panel e.g. inverted clock
58 	 */
59 	u32 bus_flags;
60 };
61 
62 /**
63  * struct tpg110 - state container for the TPG110 panel
64  */
65 struct tpg110 {
66 	/**
67 	 * @dev: the container device
68 	 */
69 	struct device *dev;
70 	/**
71 	 * @spi: the corresponding SPI device
72 	 */
73 	struct spi_device *spi;
74 	/**
75 	 * @panel: the DRM panel instance for this device
76 	 */
77 	struct drm_panel panel;
78 	/**
79 	 * @panel_mode: the panel mode as detected
80 	 */
81 	const struct tpg110_panel_mode *panel_mode;
82 	/**
83 	 * @width: the width of this panel in mm
84 	 */
85 	u32 width;
86 	/**
87 	 * @height: the height of this panel in mm
88 	 */
89 	u32 height;
90 	/**
91 	 * @grestb: reset GPIO line
92 	 */
93 	struct gpio_desc *grestb;
94 };
95 
96 /*
97  * TPG110 modes, these are the simple modes, the dualscan modes that
98  * take 400x240 or 480x272 in and display as 800x480 are not listed.
99  */
100 static const struct tpg110_panel_mode tpg110_modes[] = {
101 	{
102 		.name = "800x480 RGB",
103 		.magic = TPG110_RES_800X480,
104 		.mode = {
105 			.clock = 33200,
106 			.hdisplay = 800,
107 			.hsync_start = 800 + 40,
108 			.hsync_end = 800 + 40 + 1,
109 			.htotal = 800 + 40 + 1 + 216,
110 			.vdisplay = 480,
111 			.vsync_start = 480 + 10,
112 			.vsync_end = 480 + 10 + 1,
113 			.vtotal = 480 + 10 + 1 + 35,
114 		},
115 		.bus_flags = DRM_BUS_FLAG_PIXDATA_DRIVE_POSEDGE,
116 	},
117 	{
118 		.name = "640x480 RGB",
119 		.magic = TPG110_RES_640X480,
120 		.mode = {
121 			.clock = 25200,
122 			.hdisplay = 640,
123 			.hsync_start = 640 + 24,
124 			.hsync_end = 640 + 24 + 1,
125 			.htotal = 640 + 24 + 1 + 136,
126 			.vdisplay = 480,
127 			.vsync_start = 480 + 18,
128 			.vsync_end = 480 + 18 + 1,
129 			.vtotal = 480 + 18 + 1 + 27,
130 		},
131 		.bus_flags = DRM_BUS_FLAG_PIXDATA_DRIVE_POSEDGE,
132 	},
133 	{
134 		.name = "480x272 RGB",
135 		.magic = TPG110_RES_480X272,
136 		.mode = {
137 			.clock = 9000,
138 			.hdisplay = 480,
139 			.hsync_start = 480 + 2,
140 			.hsync_end = 480 + 2 + 1,
141 			.htotal = 480 + 2 + 1 + 43,
142 			.vdisplay = 272,
143 			.vsync_start = 272 + 2,
144 			.vsync_end = 272 + 2 + 1,
145 			.vtotal = 272 + 2 + 1 + 12,
146 		},
147 		.bus_flags = DRM_BUS_FLAG_PIXDATA_DRIVE_POSEDGE,
148 	},
149 	{
150 		.name = "480x640 RGB",
151 		.magic = TPG110_RES_480X640,
152 		.mode = {
153 			.clock = 20500,
154 			.hdisplay = 480,
155 			.hsync_start = 480 + 2,
156 			.hsync_end = 480 + 2 + 1,
157 			.htotal = 480 + 2 + 1 + 43,
158 			.vdisplay = 640,
159 			.vsync_start = 640 + 4,
160 			.vsync_end = 640 + 4 + 1,
161 			.vtotal = 640 + 4 + 1 + 8,
162 		},
163 		.bus_flags = DRM_BUS_FLAG_PIXDATA_DRIVE_POSEDGE,
164 	},
165 	{
166 		.name = "400x240 RGB",
167 		.magic = TPG110_RES_400X240_D,
168 		.mode = {
169 			.clock = 8300,
170 			.hdisplay = 400,
171 			.hsync_start = 400 + 20,
172 			.hsync_end = 400 + 20 + 1,
173 			.htotal = 400 + 20 + 1 + 108,
174 			.vdisplay = 240,
175 			.vsync_start = 240 + 2,
176 			.vsync_end = 240 + 2 + 1,
177 			.vtotal = 240 + 2 + 1 + 20,
178 		},
179 		.bus_flags = DRM_BUS_FLAG_PIXDATA_DRIVE_POSEDGE,
180 	},
181 };
182 
183 static inline struct tpg110 *
184 to_tpg110(struct drm_panel *panel)
185 {
186 	return container_of(panel, struct tpg110, panel);
187 }
188 
189 static u8 tpg110_readwrite_reg(struct tpg110 *tpg, bool write,
190 			       u8 address, u8 outval)
191 {
192 	struct spi_message m;
193 	struct spi_transfer t[2];
194 	u8 buf[2];
195 	int ret;
196 
197 	spi_message_init(&m);
198 	memset(t, 0, sizeof(t));
199 
200 	if (write) {
201 		/*
202 		 * Clear address bit 0, 1 when writing, just to be sure
203 		 * The actual bit indicating a write here is bit 1, bit
204 		 * 0 is just surplus to pad it up to 8 bits.
205 		 */
206 		buf[0] = address << 2;
207 		buf[0] &= ~0x03;
208 		buf[1] = outval;
209 
210 		t[0].bits_per_word = 8;
211 		t[0].tx_buf = &buf[0];
212 		t[0].len = 1;
213 
214 		t[1].tx_buf = &buf[1];
215 		t[1].len = 1;
216 		t[1].bits_per_word = 8;
217 	} else {
218 		/* Set address bit 0 to 1 to read */
219 		buf[0] = address << 1;
220 		buf[0] |= 0x01;
221 
222 		/*
223 		 * The last bit/clock is Hi-Z turnaround cycle, so we need
224 		 * to send only 7 bits here. The 8th bit is the high impedance
225 		 * turn-around cycle.
226 		 */
227 		t[0].bits_per_word = 7;
228 		t[0].tx_buf = &buf[0];
229 		t[0].len = 1;
230 
231 		t[1].rx_buf = &buf[1];
232 		t[1].len = 1;
233 		t[1].bits_per_word = 8;
234 	}
235 
236 	spi_message_add_tail(&t[0], &m);
237 	spi_message_add_tail(&t[1], &m);
238 	ret = spi_sync(tpg->spi, &m);
239 	if (ret) {
240 		dev_err(tpg->dev, "SPI message error %d\n", ret);
241 		return ret;
242 	}
243 	if (write)
244 		return 0;
245 	/* Read */
246 	return buf[1];
247 }
248 
249 static u8 tpg110_read_reg(struct tpg110 *tpg, u8 address)
250 {
251 	return tpg110_readwrite_reg(tpg, false, address, 0);
252 }
253 
254 static void tpg110_write_reg(struct tpg110 *tpg, u8 address, u8 outval)
255 {
256 	tpg110_readwrite_reg(tpg, true, address, outval);
257 }
258 
259 static int tpg110_startup(struct tpg110 *tpg)
260 {
261 	u8 val;
262 	int i;
263 
264 	/* De-assert the reset signal */
265 	gpiod_set_value_cansleep(tpg->grestb, 0);
266 	usleep_range(1000, 2000);
267 	dev_dbg(tpg->dev, "de-asserted GRESTB\n");
268 
269 	/* Test display communication */
270 	tpg110_write_reg(tpg, TPG110_TEST, 0x55);
271 	val = tpg110_read_reg(tpg, TPG110_TEST);
272 	if (val != 0x55) {
273 		dev_err(tpg->dev, "failed communication test\n");
274 		return -ENODEV;
275 	}
276 
277 	val = tpg110_read_reg(tpg, TPG110_CHIPID);
278 	dev_info(tpg->dev, "TPG110 chip ID: %d version: %d\n",
279 		 val >> 4, val & 0x0f);
280 
281 	/* Show display resolution */
282 	val = tpg110_read_reg(tpg, TPG110_CTRL1);
283 	val &= TPG110_RES_MASK;
284 	switch (val) {
285 	case TPG110_RES_400X240_D:
286 		dev_info(tpg->dev, "IN 400x240 RGB -> OUT 800x480 RGB (dual scan)\n");
287 		break;
288 	case TPG110_RES_480X272_D:
289 		dev_info(tpg->dev, "IN 480x272 RGB -> OUT 800x480 RGB (dual scan)\n");
290 		break;
291 	case TPG110_RES_480X640:
292 		dev_info(tpg->dev, "480x640 RGB\n");
293 		break;
294 	case TPG110_RES_480X272:
295 		dev_info(tpg->dev, "480x272 RGB\n");
296 		break;
297 	case TPG110_RES_640X480:
298 		dev_info(tpg->dev, "640x480 RGB\n");
299 		break;
300 	case TPG110_RES_800X480:
301 		dev_info(tpg->dev, "800x480 RGB\n");
302 		break;
303 	default:
304 		dev_err(tpg->dev, "ILLEGAL RESOLUTION 0x%02x\n", val);
305 		break;
306 	}
307 
308 	/* From the producer side, this is the same resolution */
309 	if (val == TPG110_RES_480X272_D)
310 		val = TPG110_RES_480X272;
311 
312 	for (i = 0; i < ARRAY_SIZE(tpg110_modes); i++) {
313 		const struct tpg110_panel_mode *pm;
314 
315 		pm = &tpg110_modes[i];
316 		if (pm->magic == val) {
317 			tpg->panel_mode = pm;
318 			break;
319 		}
320 	}
321 	if (i == ARRAY_SIZE(tpg110_modes)) {
322 		dev_err(tpg->dev, "unsupported mode (%02x) detected\n", val);
323 		return -ENODEV;
324 	}
325 
326 	val = tpg110_read_reg(tpg, TPG110_CTRL2);
327 	dev_info(tpg->dev, "resolution and standby is controlled by %s\n",
328 		 (val & TPG110_CTRL2_RES_PM_CTRL) ? "software" : "hardware");
329 	/* Take control over resolution and standby */
330 	val |= TPG110_CTRL2_RES_PM_CTRL;
331 	tpg110_write_reg(tpg, TPG110_CTRL2, val);
332 
333 	return 0;
334 }
335 
336 static int tpg110_disable(struct drm_panel *panel)
337 {
338 	struct tpg110 *tpg = to_tpg110(panel);
339 	u8 val;
340 
341 	/* Put chip into standby */
342 	val = tpg110_read_reg(tpg, TPG110_CTRL2_PM);
343 	val &= ~TPG110_CTRL2_PM;
344 	tpg110_write_reg(tpg, TPG110_CTRL2_PM, val);
345 
346 	return 0;
347 }
348 
349 static int tpg110_enable(struct drm_panel *panel)
350 {
351 	struct tpg110 *tpg = to_tpg110(panel);
352 	u8 val;
353 
354 	/* Take chip out of standby */
355 	val = tpg110_read_reg(tpg, TPG110_CTRL2_PM);
356 	val |= TPG110_CTRL2_PM;
357 	tpg110_write_reg(tpg, TPG110_CTRL2_PM, val);
358 
359 	return 0;
360 }
361 
362 /**
363  * tpg110_get_modes() - return the appropriate mode
364  * @panel: the panel to get the mode for
365  * @connector: reference to the central DRM connector control structure
366  *
367  * This currently does not present a forest of modes, instead it
368  * presents the mode that is configured for the system under use,
369  * and which is detected by reading the registers of the display.
370  */
371 static int tpg110_get_modes(struct drm_panel *panel,
372 			    struct drm_connector *connector)
373 {
374 	struct tpg110 *tpg = to_tpg110(panel);
375 	struct drm_display_mode *mode;
376 
377 	connector->display_info.width_mm = tpg->width;
378 	connector->display_info.height_mm = tpg->height;
379 	connector->display_info.bus_flags = tpg->panel_mode->bus_flags;
380 
381 	mode = drm_mode_duplicate(connector->dev, &tpg->panel_mode->mode);
382 	drm_mode_set_name(mode);
383 	mode->type = DRM_MODE_TYPE_DRIVER | DRM_MODE_TYPE_PREFERRED;
384 
385 	mode->width_mm = tpg->width;
386 	mode->height_mm = tpg->height;
387 
388 	drm_mode_probed_add(connector, mode);
389 
390 	return 1;
391 }
392 
393 static const struct drm_panel_funcs tpg110_drm_funcs = {
394 	.disable = tpg110_disable,
395 	.enable = tpg110_enable,
396 	.get_modes = tpg110_get_modes,
397 };
398 
399 static int tpg110_probe(struct spi_device *spi)
400 {
401 	struct device *dev = &spi->dev;
402 	struct device_node *np = dev->of_node;
403 	struct tpg110 *tpg;
404 	int ret;
405 
406 	tpg = devm_kzalloc(dev, sizeof(*tpg), GFP_KERNEL);
407 	if (!tpg)
408 		return -ENOMEM;
409 	tpg->dev = dev;
410 
411 	/* We get the physical display dimensions from the DT */
412 	ret = of_property_read_u32(np, "width-mm", &tpg->width);
413 	if (ret)
414 		dev_err(dev, "no panel width specified\n");
415 	ret = of_property_read_u32(np, "height-mm", &tpg->height);
416 	if (ret)
417 		dev_err(dev, "no panel height specified\n");
418 
419 	/* This asserts the GRESTB signal, putting the display into reset */
420 	tpg->grestb = devm_gpiod_get(dev, "grestb", GPIOD_OUT_HIGH);
421 	if (IS_ERR(tpg->grestb)) {
422 		dev_err(dev, "no GRESTB GPIO\n");
423 		return -ENODEV;
424 	}
425 
426 	spi->bits_per_word = 8;
427 	spi->mode |= SPI_3WIRE_HIZ;
428 	ret = spi_setup(spi);
429 	if (ret < 0) {
430 		dev_err(dev, "spi setup failed.\n");
431 		return ret;
432 	}
433 	tpg->spi = spi;
434 
435 	ret = tpg110_startup(tpg);
436 	if (ret)
437 		return ret;
438 
439 	drm_panel_init(&tpg->panel, dev, &tpg110_drm_funcs,
440 		       DRM_MODE_CONNECTOR_DPI);
441 
442 	ret = drm_panel_of_backlight(&tpg->panel);
443 	if (ret)
444 		return ret;
445 
446 	spi_set_drvdata(spi, tpg);
447 
448 	drm_panel_add(&tpg->panel);
449 
450 	return 0;
451 }
452 
453 static void tpg110_remove(struct spi_device *spi)
454 {
455 	struct tpg110 *tpg = spi_get_drvdata(spi);
456 
457 	drm_panel_remove(&tpg->panel);
458 }
459 
460 static const struct of_device_id tpg110_match[] = {
461 	{ .compatible = "tpo,tpg110", },
462 	{},
463 };
464 MODULE_DEVICE_TABLE(of, tpg110_match);
465 
466 static struct spi_driver tpg110_driver = {
467 	.probe		= tpg110_probe,
468 	.remove		= tpg110_remove,
469 	.driver		= {
470 		.name	= "tpo-tpg110-panel",
471 		.of_match_table = tpg110_match,
472 	},
473 };
474 module_spi_driver(tpg110_driver);
475 
476 MODULE_AUTHOR("Linus Walleij <linus.walleij@linaro.org>");
477 MODULE_DESCRIPTION("TPO TPG110 panel driver");
478 MODULE_LICENSE("GPL v2");
479