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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#include <drm/drm_print.h>
16
17#include <linux/backlight.h>
18#include <linux/bitops.h>
19#include <linux/delay.h>
20#include <linux/gpio/consumer.h>
21#include <linux/init.h>
22#include <linux/kernel.h>
23#include <linux/module.h>
24#include <linux/platform_device.h>
25#include <linux/spi/spi.h>
26
27#define TPG110_TEST 0x00
28#define TPG110_CHIPID 0x01
29#define TPG110_CTRL1 0x02
30#define TPG110_RES_MASK GENMASK(2, 0)
31#define TPG110_RES_800X480 0x07
32#define TPG110_RES_640X480 0x06
33#define TPG110_RES_480X272 0x05
34#define TPG110_RES_480X640 0x04
35#define TPG110_RES_480X272_D 0x01 /* Dual scan: outputs 800x480 */
36#define TPG110_RES_400X240_D 0x00 /* Dual scan: outputs 800x480 */
37#define TPG110_CTRL2 0x03
38#define TPG110_CTRL2_PM BIT(0)
39#define TPG110_CTRL2_RES_PM_CTRL BIT(7)
40
41/**
42 * struct tpg110_panel_mode - lookup struct for the supported modes
43 */
44struct tpg110_panel_mode {
45 /**
46 * @name: the name of this panel
47 */
48 const char *name;
49 /**
50 * @magic: the magic value from the detection register
51 */
52 u32 magic;
53 /**
54 * @mode: the DRM display mode for this panel
55 */
56 struct drm_display_mode mode;
57 /**
58 * @bus_flags: the DRM bus flags for this panel e.g. inverted clock
59 */
60 u32 bus_flags;
61};
62
63/**
64 * struct tpg110 - state container for the TPG110 panel
65 */
66struct tpg110 {
67 /**
68 * @dev: the container device
69 */
70 struct device *dev;
71 /**
72 * @spi: the corresponding SPI device
73 */
74 struct spi_device *spi;
75 /**
76 * @panel: the DRM panel instance for this device
77 */
78 struct drm_panel panel;
79 /**
80 * @backlight: backlight for this panel
81 */
82 struct backlight_device *backlight;
83 /**
84 * @panel_type: the panel mode as detected
85 */
86 const struct tpg110_panel_mode *panel_mode;
87 /**
88 * @width: the width of this panel in mm
89 */
90 u32 width;
91 /**
92 * @height: the height of this panel in mm
93 */
94 u32 height;
95 /**
96 * @grestb: reset GPIO line
97 */
98 struct gpio_desc *grestb;
99};
100
101/*
102 * TPG110 modes, these are the simple modes, the dualscan modes that
103 * take 400x240 or 480x272 in and display as 800x480 are not listed.
104 */
105static const struct tpg110_panel_mode tpg110_modes[] = {
106 {
107 .name = "800x480 RGB",
108 .magic = TPG110_RES_800X480,
109 .mode = {
110 .clock = 33200,
111 .hdisplay = 800,
112 .hsync_start = 800 + 40,
113 .hsync_end = 800 + 40 + 1,
114 .htotal = 800 + 40 + 1 + 216,
115 .vdisplay = 480,
116 .vsync_start = 480 + 10,
117 .vsync_end = 480 + 10 + 1,
118 .vtotal = 480 + 10 + 1 + 35,
119 .vrefresh = 60,
120 },
121 .bus_flags = DRM_BUS_FLAG_PIXDATA_DRIVE_POSEDGE,
122 },
123 {
124 .name = "640x480 RGB",
125 .magic = TPG110_RES_640X480,
126 .mode = {
127 .clock = 25200,
128 .hdisplay = 640,
129 .hsync_start = 640 + 24,
130 .hsync_end = 640 + 24 + 1,
131 .htotal = 640 + 24 + 1 + 136,
132 .vdisplay = 480,
133 .vsync_start = 480 + 18,
134 .vsync_end = 480 + 18 + 1,
135 .vtotal = 480 + 18 + 1 + 27,
136 .vrefresh = 60,
137 },
138 .bus_flags = DRM_BUS_FLAG_PIXDATA_DRIVE_POSEDGE,
139 },
140 {
141 .name = "480x272 RGB",
142 .magic = TPG110_RES_480X272,
143 .mode = {
144 .clock = 9000,
145 .hdisplay = 480,
146 .hsync_start = 480 + 2,
147 .hsync_end = 480 + 2 + 1,
148 .htotal = 480 + 2 + 1 + 43,
149 .vdisplay = 272,
150 .vsync_start = 272 + 2,
151 .vsync_end = 272 + 2 + 1,
152 .vtotal = 272 + 2 + 1 + 12,
153 .vrefresh = 60,
154 },
155 .bus_flags = DRM_BUS_FLAG_PIXDATA_DRIVE_POSEDGE,
156 },
157 {
158 .name = "480x640 RGB",
159 .magic = TPG110_RES_480X640,
160 .mode = {
161 .clock = 20500,
162 .hdisplay = 480,
163 .hsync_start = 480 + 2,
164 .hsync_end = 480 + 2 + 1,
165 .htotal = 480 + 2 + 1 + 43,
166 .vdisplay = 640,
167 .vsync_start = 640 + 4,
168 .vsync_end = 640 + 4 + 1,
169 .vtotal = 640 + 4 + 1 + 8,
170 .vrefresh = 60,
171 },
172 .bus_flags = DRM_BUS_FLAG_PIXDATA_DRIVE_POSEDGE,
173 },
174 {
175 .name = "400x240 RGB",
176 .magic = TPG110_RES_400X240_D,
177 .mode = {
178 .clock = 8300,
179 .hdisplay = 400,
180 .hsync_start = 400 + 20,
181 .hsync_end = 400 + 20 + 1,
182 .htotal = 400 + 20 + 1 + 108,
183 .vdisplay = 240,
184 .vsync_start = 240 + 2,
185 .vsync_end = 240 + 2 + 1,
186 .vtotal = 240 + 2 + 1 + 20,
187 .vrefresh = 60,
188 },
189 .bus_flags = DRM_BUS_FLAG_PIXDATA_DRIVE_POSEDGE,
190 },
191};
192
193static inline struct tpg110 *
194to_tpg110(struct drm_panel *panel)
195{
196 return container_of(panel, struct tpg110, panel);
197}
198
199static u8 tpg110_readwrite_reg(struct tpg110 *tpg, bool write,
200 u8 address, u8 outval)
201{
202 struct spi_message m;
203 struct spi_transfer t[2];
204 u8 buf[2];
205 int ret;
206
207 spi_message_init(&m);
208 memset(t, 0, sizeof(t));
209
210 if (write) {
211 /*
212 * Clear address bit 0, 1 when writing, just to be sure
213 * The actual bit indicating a write here is bit 1, bit
214 * 0 is just surplus to pad it up to 8 bits.
215 */
216 buf[0] = address << 2;
217 buf[0] &= ~0x03;
218 buf[1] = outval;
219
220 t[0].bits_per_word = 8;
221 t[0].tx_buf = &buf[0];
222 t[0].len = 1;
223
224 t[1].tx_buf = &buf[1];
225 t[1].len = 1;
226 t[1].bits_per_word = 8;
227 } else {
228 /* Set address bit 0 to 1 to read */
229 buf[0] = address << 1;
230 buf[0] |= 0x01;
231
232 /*
233 * The last bit/clock is Hi-Z turnaround cycle, so we need
234 * to send only 7 bits here. The 8th bit is the high impedance
235 * turn-around cycle.
236 */
237 t[0].bits_per_word = 7;
238 t[0].tx_buf = &buf[0];
239 t[0].len = 1;
240
241 t[1].rx_buf = &buf[1];
242 t[1].len = 1;
243 t[1].bits_per_word = 8;
244 }
245
246 spi_message_add_tail(&t[0], &m);
247 spi_message_add_tail(&t[1], &m);
248 ret = spi_sync(tpg->spi, &m);
249 if (ret) {
250 DRM_DEV_ERROR(tpg->dev, "SPI message error %d\n", ret);
251 return ret;
252 }
253 if (write)
254 return 0;
255 /* Read */
256 return buf[1];
257}
258
259static u8 tpg110_read_reg(struct tpg110 *tpg, u8 address)
260{
261 return tpg110_readwrite_reg(tpg, false, address, 0);
262}
263
264static void tpg110_write_reg(struct tpg110 *tpg, u8 address, u8 outval)
265{
266 tpg110_readwrite_reg(tpg, true, address, outval);
267}
268
269static int tpg110_startup(struct tpg110 *tpg)
270{
271 u8 val;
272 int i;
273
274 /* De-assert the reset signal */
275 gpiod_set_value_cansleep(tpg->grestb, 0);
276 usleep_range(1000, 2000);
277 DRM_DEV_DEBUG(tpg->dev, "de-asserted GRESTB\n");
278
279 /* Test display communication */
280 tpg110_write_reg(tpg, TPG110_TEST, 0x55);
281 val = tpg110_read_reg(tpg, TPG110_TEST);
282 if (val != 0x55) {
283 DRM_DEV_ERROR(tpg->dev, "failed communication test\n");
284 return -ENODEV;
285 }
286
287 val = tpg110_read_reg(tpg, TPG110_CHIPID);
288 DRM_DEV_INFO(tpg->dev, "TPG110 chip ID: %d version: %d\n",
289 val >> 4, val & 0x0f);
290
291 /* Show display resolution */
292 val = tpg110_read_reg(tpg, TPG110_CTRL1);
293 val &= TPG110_RES_MASK;
294 switch (val) {
295 case TPG110_RES_400X240_D:
296 DRM_DEV_INFO(tpg->dev,
297 "IN 400x240 RGB -> OUT 800x480 RGB (dual scan)\n");
298 break;
299 case TPG110_RES_480X272_D:
300 DRM_DEV_INFO(tpg->dev,
301 "IN 480x272 RGB -> OUT 800x480 RGB (dual scan)\n");
302 break;
303 case TPG110_RES_480X640:
304 DRM_DEV_INFO(tpg->dev, "480x640 RGB\n");
305 break;
306 case TPG110_RES_480X272:
307 DRM_DEV_INFO(tpg->dev, "480x272 RGB\n");
308 break;
309 case TPG110_RES_640X480:
310 DRM_DEV_INFO(tpg->dev, "640x480 RGB\n");
311 break;
312 case TPG110_RES_800X480:
313 DRM_DEV_INFO(tpg->dev, "800x480 RGB\n");
314 break;
315 default:
316 DRM_DEV_ERROR(tpg->dev, "ILLEGAL RESOLUTION 0x%02x\n", val);
317 break;
318 }
319
320 /* From the producer side, this is the same resolution */
321 if (val == TPG110_RES_480X272_D)
322 val = TPG110_RES_480X272;
323
324 for (i = 0; i < ARRAY_SIZE(tpg110_modes); i++) {
325 const struct tpg110_panel_mode *pm;
326
327 pm = &tpg110_modes[i];
328 if (pm->magic == val) {
329 tpg->panel_mode = pm;
330 break;
331 }
332 }
333 if (i == ARRAY_SIZE(tpg110_modes)) {
334 DRM_DEV_ERROR(tpg->dev, "unsupported mode (%02x) detected\n",
335 val);
336 return -ENODEV;
337 }
338
339 val = tpg110_read_reg(tpg, TPG110_CTRL2);
340 DRM_DEV_INFO(tpg->dev, "resolution and standby is controlled by %s\n",
341 (val & TPG110_CTRL2_RES_PM_CTRL) ? "software" : "hardware");
342 /* Take control over resolution and standby */
343 val |= TPG110_CTRL2_RES_PM_CTRL;
344 tpg110_write_reg(tpg, TPG110_CTRL2, val);
345
346 return 0;
347}
348
349static int tpg110_disable(struct drm_panel *panel)
350{
351 struct tpg110 *tpg = to_tpg110(panel);
352 u8 val;
353
354 /* Put chip into 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 backlight_disable(tpg->backlight);
360
361 return 0;
362}
363
364static int tpg110_enable(struct drm_panel *panel)
365{
366 struct tpg110 *tpg = to_tpg110(panel);
367 u8 val;
368
369 backlight_enable(tpg->backlight);
370
371 /* Take chip out of standby */
372 val = tpg110_read_reg(tpg, TPG110_CTRL2_PM);
373 val |= TPG110_CTRL2_PM;
374 tpg110_write_reg(tpg, TPG110_CTRL2_PM, val);
375
376 return 0;
377}
378
379/**
380 * tpg110_get_modes() - return the appropriate mode
381 * @panel: the panel to get the mode for
382 *
383 * This currently does not present a forest of modes, instead it
384 * presents the mode that is configured for the system under use,
385 * and which is detected by reading the registers of the display.
386 */
387static int tpg110_get_modes(struct drm_panel *panel)
388{
389 struct drm_connector *connector = panel->connector;
390 struct tpg110 *tpg = to_tpg110(panel);
391 struct drm_display_mode *mode;
392
393 connector->display_info.width_mm = tpg->width;
394 connector->display_info.height_mm = tpg->height;
395 connector->display_info.bus_flags = tpg->panel_mode->bus_flags;
396
397 mode = drm_mode_duplicate(panel->drm, &tpg->panel_mode->mode);
398 drm_mode_set_name(mode);
399 mode->type = DRM_MODE_TYPE_DRIVER | DRM_MODE_TYPE_PREFERRED;
400
401 mode->width_mm = tpg->width;
402 mode->height_mm = tpg->height;
403
404 drm_mode_probed_add(connector, mode);
405
406 return 1;
407}
408
409static const struct drm_panel_funcs tpg110_drm_funcs = {
410 .disable = tpg110_disable,
411 .enable = tpg110_enable,
412 .get_modes = tpg110_get_modes,
413};
414
415static int tpg110_probe(struct spi_device *spi)
416{
417 struct device *dev = &spi->dev;
418 struct device_node *np = dev->of_node;
419 struct tpg110 *tpg;
420 int ret;
421
422 tpg = devm_kzalloc(dev, sizeof(*tpg), GFP_KERNEL);
423 if (!tpg)
424 return -ENOMEM;
425 tpg->dev = dev;
426
427 /* We get the physical display dimensions from the DT */
428 ret = of_property_read_u32(np, "width-mm", &tpg->width);
429 if (ret)
430 DRM_DEV_ERROR(dev, "no panel width specified\n");
431 ret = of_property_read_u32(np, "height-mm", &tpg->height);
432 if (ret)
433 DRM_DEV_ERROR(dev, "no panel height specified\n");
434
435 /* Look for some optional backlight */
436 tpg->backlight = devm_of_find_backlight(dev);
437 if (IS_ERR(tpg->backlight))
438 return PTR_ERR(tpg->backlight);
439
440 /* This asserts the GRESTB signal, putting the display into reset */
441 tpg->grestb = devm_gpiod_get(dev, "grestb", GPIOD_OUT_HIGH);
442 if (IS_ERR(tpg->grestb)) {
443 DRM_DEV_ERROR(dev, "no GRESTB GPIO\n");
444 return -ENODEV;
445 }
446
447 spi->bits_per_word = 8;
448 spi->mode |= SPI_3WIRE_HIZ;
449 ret = spi_setup(spi);
450 if (ret < 0) {
451 DRM_DEV_ERROR(dev, "spi setup failed.\n");
452 return ret;
453 }
454 tpg->spi = spi;
455
456 ret = tpg110_startup(tpg);
457 if (ret)
458 return ret;
459
460 drm_panel_init(&tpg->panel);
461 tpg->panel.dev = dev;
462 tpg->panel.funcs = &tpg110_drm_funcs;
463 spi_set_drvdata(spi, tpg);
464
465 return drm_panel_add(&tpg->panel);
466}
467
468static int tpg110_remove(struct spi_device *spi)
469{
470 struct tpg110 *tpg = spi_get_drvdata(spi);
471
472 drm_panel_remove(&tpg->panel);
473 return 0;
474}
475
476static const struct of_device_id tpg110_match[] = {
477 { .compatible = "tpo,tpg110", },
478 {},
479};
480MODULE_DEVICE_TABLE(of, tpg110_match);
481
482static struct spi_driver tpg110_driver = {
483 .probe = tpg110_probe,
484 .remove = tpg110_remove,
485 .driver = {
486 .name = "tpo-tpg110-panel",
487 .of_match_table = tpg110_match,
488 },
489};
490module_spi_driver(tpg110_driver);
491
492MODULE_AUTHOR("Linus Walleij <linus.walleij@linaro.org>");
493MODULE_DESCRIPTION("TPO TPG110 panel driver");
494MODULE_LICENSE("GPL v2");