1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * Copyright (c) 2016 MediaTek Inc.
4  */
5 
6 #include <linux/delay.h>
7 #include <linux/err.h>
8 #include <linux/gpio/consumer.h>
9 #include <linux/i2c.h>
10 #include <linux/module.h>
11 #include <linux/of_graph.h>
12 #include <linux/pm_runtime.h>
13 #include <linux/regmap.h>
14 #include <linux/regulator/consumer.h>
15 
16 #include <drm/display/drm_dp_aux_bus.h>
17 #include <drm/display/drm_dp_helper.h>
18 #include <drm/drm_atomic_state_helper.h>
19 #include <drm/drm_bridge.h>
20 #include <drm/drm_edid.h>
21 #include <drm/drm_mipi_dsi.h>
22 #include <drm/drm_of.h>
23 #include <drm/drm_panel.h>
24 #include <drm/drm_print.h>
25 
26 #define PAGE0_AUXCH_CFG3	0x76
27 #define  AUXCH_CFG3_RESET	0xff
28 #define PAGE0_SWAUX_ADDR_7_0	0x7d
29 #define PAGE0_SWAUX_ADDR_15_8	0x7e
30 #define PAGE0_SWAUX_ADDR_23_16	0x7f
31 #define  SWAUX_ADDR_MASK	GENMASK(19, 0)
32 #define PAGE0_SWAUX_LENGTH	0x80
33 #define  SWAUX_LENGTH_MASK	GENMASK(3, 0)
34 #define  SWAUX_NO_PAYLOAD	BIT(7)
35 #define PAGE0_SWAUX_WDATA	0x81
36 #define PAGE0_SWAUX_RDATA	0x82
37 #define PAGE0_SWAUX_CTRL	0x83
38 #define  SWAUX_SEND		BIT(0)
39 #define PAGE0_SWAUX_STATUS	0x84
40 #define  SWAUX_M_MASK		GENMASK(4, 0)
41 #define  SWAUX_STATUS_MASK	GENMASK(7, 5)
42 #define  SWAUX_STATUS_NACK	(0x1 << 5)
43 #define  SWAUX_STATUS_DEFER	(0x2 << 5)
44 #define  SWAUX_STATUS_ACKM	(0x3 << 5)
45 #define  SWAUX_STATUS_INVALID	(0x4 << 5)
46 #define  SWAUX_STATUS_I2C_NACK	(0x5 << 5)
47 #define  SWAUX_STATUS_I2C_DEFER	(0x6 << 5)
48 #define  SWAUX_STATUS_TIMEOUT	(0x7 << 5)
49 
50 #define PAGE2_GPIO_H		0xa7
51 #define  PS_GPIO9		BIT(1)
52 #define PAGE2_I2C_BYPASS	0xea
53 #define  I2C_BYPASS_EN		0xd0
54 #define PAGE2_MCS_EN		0xf3
55 #define  MCS_EN			BIT(0)
56 
57 #define PAGE3_SET_ADD		0xfe
58 #define  VDO_CTL_ADD		0x13
59 #define  VDO_DIS		0x18
60 #define  VDO_EN			0x1c
61 
62 #define NUM_MIPI_LANES		4
63 
64 #define COMMON_PS8640_REGMAP_CONFIG \
65 	.reg_bits = 8, \
66 	.val_bits = 8, \
67 	.cache_type = REGCACHE_NONE
68 
69 /*
70  * PS8640 uses multiple addresses:
71  * page[0]: for DP control
72  * page[1]: for VIDEO Bridge
73  * page[2]: for control top
74  * page[3]: for DSI Link Control1
75  * page[4]: for MIPI Phy
76  * page[5]: for VPLL
77  * page[6]: for DSI Link Control2
78  * page[7]: for SPI ROM mapping
79  */
80 enum page_addr_offset {
81 	PAGE0_DP_CNTL = 0,
82 	PAGE1_VDO_BDG,
83 	PAGE2_TOP_CNTL,
84 	PAGE3_DSI_CNTL1,
85 	PAGE4_MIPI_PHY,
86 	PAGE5_VPLL,
87 	PAGE6_DSI_CNTL2,
88 	PAGE7_SPI_CNTL,
89 	MAX_DEVS
90 };
91 
92 enum ps8640_vdo_control {
93 	DISABLE = VDO_DIS,
94 	ENABLE = VDO_EN,
95 };
96 
97 struct ps8640 {
98 	struct drm_bridge bridge;
99 	struct drm_bridge *panel_bridge;
100 	struct drm_dp_aux aux;
101 	struct mipi_dsi_device *dsi;
102 	struct i2c_client *page[MAX_DEVS];
103 	struct regmap	*regmap[MAX_DEVS];
104 	struct regulator_bulk_data supplies[2];
105 	struct gpio_desc *gpio_reset;
106 	struct gpio_desc *gpio_powerdown;
107 	struct device_link *link;
108 	bool pre_enabled;
109 	bool need_post_hpd_delay;
110 	struct mutex aux_lock;
111 };
112 
113 static const struct regmap_config ps8640_regmap_config[] = {
114 	[PAGE0_DP_CNTL] = {
115 		COMMON_PS8640_REGMAP_CONFIG,
116 		.max_register = 0xbf,
117 	},
118 	[PAGE1_VDO_BDG] = {
119 		COMMON_PS8640_REGMAP_CONFIG,
120 		.max_register = 0xff,
121 	},
122 	[PAGE2_TOP_CNTL] = {
123 		COMMON_PS8640_REGMAP_CONFIG,
124 		.max_register = 0xff,
125 	},
126 	[PAGE3_DSI_CNTL1] = {
127 		COMMON_PS8640_REGMAP_CONFIG,
128 		.max_register = 0xff,
129 	},
130 	[PAGE4_MIPI_PHY] = {
131 		COMMON_PS8640_REGMAP_CONFIG,
132 		.max_register = 0xff,
133 	},
134 	[PAGE5_VPLL] = {
135 		COMMON_PS8640_REGMAP_CONFIG,
136 		.max_register = 0x7f,
137 	},
138 	[PAGE6_DSI_CNTL2] = {
139 		COMMON_PS8640_REGMAP_CONFIG,
140 		.max_register = 0xff,
141 	},
142 	[PAGE7_SPI_CNTL] = {
143 		COMMON_PS8640_REGMAP_CONFIG,
144 		.max_register = 0xff,
145 	},
146 };
147 
148 static inline struct ps8640 *bridge_to_ps8640(struct drm_bridge *e)
149 {
150 	return container_of(e, struct ps8640, bridge);
151 }
152 
153 static inline struct ps8640 *aux_to_ps8640(struct drm_dp_aux *aux)
154 {
155 	return container_of(aux, struct ps8640, aux);
156 }
157 
158 static int _ps8640_wait_hpd_asserted(struct ps8640 *ps_bridge, unsigned long wait_us)
159 {
160 	struct regmap *map = ps_bridge->regmap[PAGE2_TOP_CNTL];
161 	int status;
162 	int ret;
163 
164 	/*
165 	 * Apparently something about the firmware in the chip signals that
166 	 * HPD goes high by reporting GPIO9 as high (even though HPD isn't
167 	 * actually connected to GPIO9).
168 	 */
169 	ret = regmap_read_poll_timeout(map, PAGE2_GPIO_H, status,
170 				       status & PS_GPIO9, 20000, wait_us);
171 
172 	/*
173 	 * The first time we see HPD go high after a reset we delay an extra
174 	 * 50 ms. The best guess is that the MCU is doing "stuff" during this
175 	 * time (maybe talking to the panel) and we don't want to interrupt it.
176 	 *
177 	 * No locking is done around "need_post_hpd_delay". If we're here we
178 	 * know we're holding a PM Runtime reference and the only other place
179 	 * that touches this is PM Runtime resume.
180 	 */
181 	if (!ret && ps_bridge->need_post_hpd_delay) {
182 		ps_bridge->need_post_hpd_delay = false;
183 		msleep(50);
184 	}
185 
186 	return ret;
187 }
188 
189 static int ps8640_wait_hpd_asserted(struct drm_dp_aux *aux, unsigned long wait_us)
190 {
191 	struct ps8640 *ps_bridge = aux_to_ps8640(aux);
192 	struct device *dev = &ps_bridge->page[PAGE0_DP_CNTL]->dev;
193 	int ret;
194 
195 	/*
196 	 * Note that this function is called by code that has already powered
197 	 * the panel. We have to power ourselves up but we don't need to worry
198 	 * about powering the panel.
199 	 */
200 	pm_runtime_get_sync(dev);
201 	ret = _ps8640_wait_hpd_asserted(ps_bridge, wait_us);
202 	pm_runtime_mark_last_busy(dev);
203 	pm_runtime_put_autosuspend(dev);
204 
205 	return ret;
206 }
207 
208 static ssize_t ps8640_aux_transfer_msg(struct drm_dp_aux *aux,
209 				       struct drm_dp_aux_msg *msg)
210 {
211 	struct ps8640 *ps_bridge = aux_to_ps8640(aux);
212 	struct regmap *map = ps_bridge->regmap[PAGE0_DP_CNTL];
213 	struct device *dev = &ps_bridge->page[PAGE0_DP_CNTL]->dev;
214 	size_t len = msg->size;
215 	unsigned int data;
216 	unsigned int base;
217 	int ret;
218 	u8 request = msg->request &
219 		     ~(DP_AUX_I2C_MOT | DP_AUX_I2C_WRITE_STATUS_UPDATE);
220 	u8 *buf = msg->buffer;
221 	u8 addr_len[PAGE0_SWAUX_LENGTH + 1 - PAGE0_SWAUX_ADDR_7_0];
222 	u8 i;
223 	bool is_native_aux = false;
224 
225 	if (len > DP_AUX_MAX_PAYLOAD_BYTES)
226 		return -EINVAL;
227 
228 	if (msg->address & ~SWAUX_ADDR_MASK)
229 		return -EINVAL;
230 
231 	switch (request) {
232 	case DP_AUX_NATIVE_WRITE:
233 	case DP_AUX_NATIVE_READ:
234 		is_native_aux = true;
235 		fallthrough;
236 	case DP_AUX_I2C_WRITE:
237 	case DP_AUX_I2C_READ:
238 		break;
239 	default:
240 		return -EINVAL;
241 	}
242 
243 	ret = regmap_write(map, PAGE0_AUXCH_CFG3, AUXCH_CFG3_RESET);
244 	if (ret) {
245 		DRM_DEV_ERROR(dev, "failed to write PAGE0_AUXCH_CFG3: %d\n",
246 			      ret);
247 		return ret;
248 	}
249 
250 	/* Assume it's good */
251 	msg->reply = 0;
252 
253 	base = PAGE0_SWAUX_ADDR_7_0;
254 	addr_len[PAGE0_SWAUX_ADDR_7_0 - base] = msg->address;
255 	addr_len[PAGE0_SWAUX_ADDR_15_8 - base] = msg->address >> 8;
256 	addr_len[PAGE0_SWAUX_ADDR_23_16 - base] = (msg->address >> 16) |
257 						  (msg->request << 4);
258 	addr_len[PAGE0_SWAUX_LENGTH - base] = (len == 0) ? SWAUX_NO_PAYLOAD :
259 					      ((len - 1) & SWAUX_LENGTH_MASK);
260 
261 	regmap_bulk_write(map, PAGE0_SWAUX_ADDR_7_0, addr_len,
262 			  ARRAY_SIZE(addr_len));
263 
264 	if (len && (request == DP_AUX_NATIVE_WRITE ||
265 		    request == DP_AUX_I2C_WRITE)) {
266 		/* Write to the internal FIFO buffer */
267 		for (i = 0; i < len; i++) {
268 			ret = regmap_write(map, PAGE0_SWAUX_WDATA, buf[i]);
269 			if (ret) {
270 				DRM_DEV_ERROR(dev,
271 					      "failed to write WDATA: %d\n",
272 					      ret);
273 				return ret;
274 			}
275 		}
276 	}
277 
278 	regmap_write(map, PAGE0_SWAUX_CTRL, SWAUX_SEND);
279 
280 	/* Zero delay loop because i2c transactions are slow already */
281 	regmap_read_poll_timeout(map, PAGE0_SWAUX_CTRL, data,
282 				 !(data & SWAUX_SEND), 0, 50 * 1000);
283 
284 	regmap_read(map, PAGE0_SWAUX_STATUS, &data);
285 	if (ret) {
286 		DRM_DEV_ERROR(dev, "failed to read PAGE0_SWAUX_STATUS: %d\n",
287 			      ret);
288 		return ret;
289 	}
290 
291 	switch (data & SWAUX_STATUS_MASK) {
292 	case SWAUX_STATUS_NACK:
293 	case SWAUX_STATUS_I2C_NACK:
294 		/*
295 		 * The programming guide is not clear about whether a I2C NACK
296 		 * would trigger SWAUX_STATUS_NACK or SWAUX_STATUS_I2C_NACK. So
297 		 * we handle both cases together.
298 		 */
299 		if (is_native_aux)
300 			msg->reply |= DP_AUX_NATIVE_REPLY_NACK;
301 		else
302 			msg->reply |= DP_AUX_I2C_REPLY_NACK;
303 
304 		fallthrough;
305 	case SWAUX_STATUS_ACKM:
306 		len = data & SWAUX_M_MASK;
307 		break;
308 	case SWAUX_STATUS_DEFER:
309 	case SWAUX_STATUS_I2C_DEFER:
310 		if (is_native_aux)
311 			msg->reply |= DP_AUX_NATIVE_REPLY_DEFER;
312 		else
313 			msg->reply |= DP_AUX_I2C_REPLY_DEFER;
314 		len = data & SWAUX_M_MASK;
315 		break;
316 	case SWAUX_STATUS_INVALID:
317 		return -EOPNOTSUPP;
318 	case SWAUX_STATUS_TIMEOUT:
319 		return -ETIMEDOUT;
320 	}
321 
322 	if (len && (request == DP_AUX_NATIVE_READ ||
323 		    request == DP_AUX_I2C_READ)) {
324 		/* Read from the internal FIFO buffer */
325 		for (i = 0; i < len; i++) {
326 			ret = regmap_read(map, PAGE0_SWAUX_RDATA, &data);
327 			if (ret) {
328 				DRM_DEV_ERROR(dev,
329 					      "failed to read RDATA: %d\n",
330 					      ret);
331 				return ret;
332 			}
333 
334 			if (i < msg->size)
335 				buf[i] = data;
336 		}
337 	}
338 
339 	return min(len, msg->size);
340 }
341 
342 static ssize_t ps8640_aux_transfer(struct drm_dp_aux *aux,
343 				   struct drm_dp_aux_msg *msg)
344 {
345 	struct ps8640 *ps_bridge = aux_to_ps8640(aux);
346 	struct device *dev = &ps_bridge->page[PAGE0_DP_CNTL]->dev;
347 	int ret;
348 
349 	mutex_lock(&ps_bridge->aux_lock);
350 	pm_runtime_get_sync(dev);
351 	ret = _ps8640_wait_hpd_asserted(ps_bridge, 200 * 1000);
352 	if (ret) {
353 		pm_runtime_put_sync_suspend(dev);
354 		goto exit;
355 	}
356 	ret = ps8640_aux_transfer_msg(aux, msg);
357 	pm_runtime_mark_last_busy(dev);
358 	pm_runtime_put_autosuspend(dev);
359 
360 exit:
361 	mutex_unlock(&ps_bridge->aux_lock);
362 
363 	return ret;
364 }
365 
366 static void ps8640_bridge_vdo_control(struct ps8640 *ps_bridge,
367 				      const enum ps8640_vdo_control ctrl)
368 {
369 	struct regmap *map = ps_bridge->regmap[PAGE3_DSI_CNTL1];
370 	struct device *dev = &ps_bridge->page[PAGE3_DSI_CNTL1]->dev;
371 	u8 vdo_ctrl_buf[] = { VDO_CTL_ADD, ctrl };
372 	int ret;
373 
374 	ret = regmap_bulk_write(map, PAGE3_SET_ADD,
375 				vdo_ctrl_buf, sizeof(vdo_ctrl_buf));
376 
377 	if (ret < 0)
378 		dev_err(dev, "failed to %sable VDO: %d\n",
379 			ctrl == ENABLE ? "en" : "dis", ret);
380 }
381 
382 static int __maybe_unused ps8640_resume(struct device *dev)
383 {
384 	struct ps8640 *ps_bridge = dev_get_drvdata(dev);
385 	int ret;
386 
387 	ret = regulator_bulk_enable(ARRAY_SIZE(ps_bridge->supplies),
388 				    ps_bridge->supplies);
389 	if (ret < 0) {
390 		dev_err(dev, "cannot enable regulators %d\n", ret);
391 		return ret;
392 	}
393 
394 	gpiod_set_value(ps_bridge->gpio_powerdown, 0);
395 	gpiod_set_value(ps_bridge->gpio_reset, 1);
396 	usleep_range(2000, 2500);
397 	gpiod_set_value(ps_bridge->gpio_reset, 0);
398 	/* Double reset for T4 and T5 */
399 	msleep(50);
400 	gpiod_set_value(ps_bridge->gpio_reset, 1);
401 	msleep(50);
402 	gpiod_set_value(ps_bridge->gpio_reset, 0);
403 
404 	/* We just reset things, so we need a delay after the first HPD */
405 	ps_bridge->need_post_hpd_delay = true;
406 
407 	/*
408 	 * Mystery 200 ms delay for the "MCU to be ready". It's unclear if
409 	 * this is truly necessary since the MCU will already signal that
410 	 * things are "good to go" by signaling HPD on "gpio 9". See
411 	 * _ps8640_wait_hpd_asserted(). For now we'll keep this mystery delay
412 	 * just in case.
413 	 */
414 	msleep(200);
415 
416 	return 0;
417 }
418 
419 static int __maybe_unused ps8640_suspend(struct device *dev)
420 {
421 	struct ps8640 *ps_bridge = dev_get_drvdata(dev);
422 	int ret;
423 
424 	gpiod_set_value(ps_bridge->gpio_reset, 1);
425 	gpiod_set_value(ps_bridge->gpio_powerdown, 1);
426 	ret = regulator_bulk_disable(ARRAY_SIZE(ps_bridge->supplies),
427 				     ps_bridge->supplies);
428 	if (ret < 0)
429 		dev_err(dev, "cannot disable regulators %d\n", ret);
430 
431 	return ret;
432 }
433 
434 static const struct dev_pm_ops ps8640_pm_ops = {
435 	SET_RUNTIME_PM_OPS(ps8640_suspend, ps8640_resume, NULL)
436 	SET_SYSTEM_SLEEP_PM_OPS(pm_runtime_force_suspend,
437 				pm_runtime_force_resume)
438 };
439 
440 static void ps8640_atomic_pre_enable(struct drm_bridge *bridge,
441 				     struct drm_bridge_state *old_bridge_state)
442 {
443 	struct ps8640 *ps_bridge = bridge_to_ps8640(bridge);
444 	struct regmap *map = ps_bridge->regmap[PAGE2_TOP_CNTL];
445 	struct device *dev = &ps_bridge->page[PAGE0_DP_CNTL]->dev;
446 	int ret;
447 
448 	pm_runtime_get_sync(dev);
449 	ret = _ps8640_wait_hpd_asserted(ps_bridge, 200 * 1000);
450 	if (ret < 0)
451 		dev_warn(dev, "HPD didn't go high: %d\n", ret);
452 
453 	/*
454 	 * The Manufacturer Command Set (MCS) is a device dependent interface
455 	 * intended for factory programming of the display module default
456 	 * parameters. Once the display module is configured, the MCS shall be
457 	 * disabled by the manufacturer. Once disabled, all MCS commands are
458 	 * ignored by the display interface.
459 	 */
460 
461 	ret = regmap_update_bits(map, PAGE2_MCS_EN, MCS_EN, 0);
462 	if (ret < 0)
463 		dev_warn(dev, "failed write PAGE2_MCS_EN: %d\n", ret);
464 
465 	/* Switch access edp panel's edid through i2c */
466 	ret = regmap_write(map, PAGE2_I2C_BYPASS, I2C_BYPASS_EN);
467 	if (ret < 0)
468 		dev_warn(dev, "failed write PAGE2_MCS_EN: %d\n", ret);
469 
470 	ps8640_bridge_vdo_control(ps_bridge, ENABLE);
471 
472 	ps_bridge->pre_enabled = true;
473 }
474 
475 static void ps8640_atomic_post_disable(struct drm_bridge *bridge,
476 				       struct drm_bridge_state *old_bridge_state)
477 {
478 	struct ps8640 *ps_bridge = bridge_to_ps8640(bridge);
479 
480 	ps_bridge->pre_enabled = false;
481 
482 	ps8640_bridge_vdo_control(ps_bridge, DISABLE);
483 
484 	/*
485 	 * The bridge seems to expect everything to be power cycled at the
486 	 * disable process, so grab a lock here to make sure
487 	 * ps8640_aux_transfer() is not holding a runtime PM reference and
488 	 * preventing the bridge from suspend.
489 	 */
490 	mutex_lock(&ps_bridge->aux_lock);
491 
492 	pm_runtime_put_sync_suspend(&ps_bridge->page[PAGE0_DP_CNTL]->dev);
493 
494 	mutex_unlock(&ps_bridge->aux_lock);
495 }
496 
497 static int ps8640_bridge_attach(struct drm_bridge *bridge,
498 				enum drm_bridge_attach_flags flags)
499 {
500 	struct ps8640 *ps_bridge = bridge_to_ps8640(bridge);
501 	struct device *dev = &ps_bridge->page[0]->dev;
502 	int ret;
503 
504 	if (!(flags & DRM_BRIDGE_ATTACH_NO_CONNECTOR))
505 		return -EINVAL;
506 
507 	ps_bridge->aux.drm_dev = bridge->dev;
508 	ret = drm_dp_aux_register(&ps_bridge->aux);
509 	if (ret) {
510 		dev_err(dev, "failed to register DP AUX channel: %d\n", ret);
511 		return ret;
512 	}
513 
514 	ps_bridge->link = device_link_add(bridge->dev->dev, dev, DL_FLAG_STATELESS);
515 	if (!ps_bridge->link) {
516 		dev_err(dev, "failed to create device link");
517 		ret = -EINVAL;
518 		goto err_devlink;
519 	}
520 
521 	/* Attach the panel-bridge to the dsi bridge */
522 	ret = drm_bridge_attach(bridge->encoder, ps_bridge->panel_bridge,
523 				&ps_bridge->bridge, flags);
524 	if (ret)
525 		goto err_bridge_attach;
526 
527 	return 0;
528 
529 err_bridge_attach:
530 	device_link_del(ps_bridge->link);
531 err_devlink:
532 	drm_dp_aux_unregister(&ps_bridge->aux);
533 
534 	return ret;
535 }
536 
537 static void ps8640_bridge_detach(struct drm_bridge *bridge)
538 {
539 	struct ps8640 *ps_bridge = bridge_to_ps8640(bridge);
540 
541 	drm_dp_aux_unregister(&ps_bridge->aux);
542 	if (ps_bridge->link)
543 		device_link_del(ps_bridge->link);
544 }
545 
546 static void ps8640_runtime_disable(void *data)
547 {
548 	pm_runtime_dont_use_autosuspend(data);
549 	pm_runtime_disable(data);
550 }
551 
552 static const struct drm_bridge_funcs ps8640_bridge_funcs = {
553 	.attach = ps8640_bridge_attach,
554 	.detach = ps8640_bridge_detach,
555 	.atomic_post_disable = ps8640_atomic_post_disable,
556 	.atomic_pre_enable = ps8640_atomic_pre_enable,
557 	.atomic_duplicate_state = drm_atomic_helper_bridge_duplicate_state,
558 	.atomic_destroy_state = drm_atomic_helper_bridge_destroy_state,
559 	.atomic_reset = drm_atomic_helper_bridge_reset,
560 };
561 
562 static int ps8640_bridge_get_dsi_resources(struct device *dev, struct ps8640 *ps_bridge)
563 {
564 	struct device_node *in_ep, *dsi_node;
565 	struct mipi_dsi_device *dsi;
566 	struct mipi_dsi_host *host;
567 	const struct mipi_dsi_device_info info = { .type = "ps8640",
568 						   .channel = 0,
569 						   .node = NULL,
570 						 };
571 
572 	/* port@0 is ps8640 dsi input port */
573 	in_ep = of_graph_get_endpoint_by_regs(dev->of_node, 0, -1);
574 	if (!in_ep)
575 		return -ENODEV;
576 
577 	dsi_node = of_graph_get_remote_port_parent(in_ep);
578 	of_node_put(in_ep);
579 	if (!dsi_node)
580 		return -ENODEV;
581 
582 	host = of_find_mipi_dsi_host_by_node(dsi_node);
583 	of_node_put(dsi_node);
584 	if (!host)
585 		return -EPROBE_DEFER;
586 
587 	dsi = devm_mipi_dsi_device_register_full(dev, host, &info);
588 	if (IS_ERR(dsi)) {
589 		dev_err(dev, "failed to create dsi device\n");
590 		return PTR_ERR(dsi);
591 	}
592 
593 	ps_bridge->dsi = dsi;
594 
595 	dsi->host = host;
596 	dsi->mode_flags = MIPI_DSI_MODE_VIDEO |
597 			  MIPI_DSI_MODE_VIDEO_SYNC_PULSE;
598 	dsi->format = MIPI_DSI_FMT_RGB888;
599 	dsi->lanes = NUM_MIPI_LANES;
600 
601 	return 0;
602 }
603 
604 static int ps8640_bridge_link_panel(struct drm_dp_aux *aux)
605 {
606 	struct ps8640 *ps_bridge = aux_to_ps8640(aux);
607 	struct device *dev = aux->dev;
608 	struct device_node *np = dev->of_node;
609 	int ret;
610 
611 	/*
612 	 * NOTE about returning -EPROBE_DEFER from this function: if we
613 	 * return an error (most relevant to -EPROBE_DEFER) it will only
614 	 * be passed out to ps8640_probe() if it called this directly (AKA the
615 	 * panel isn't under the "aux-bus" node). That should be fine because
616 	 * if the panel is under "aux-bus" it's guaranteed to have probed by
617 	 * the time this function has been called.
618 	 */
619 
620 	/* port@1 is ps8640 output port */
621 	ps_bridge->panel_bridge = devm_drm_of_get_bridge(dev, np, 1, 0);
622 	if (IS_ERR(ps_bridge->panel_bridge))
623 		return PTR_ERR(ps_bridge->panel_bridge);
624 
625 	ret = devm_drm_bridge_add(dev, &ps_bridge->bridge);
626 	if (ret)
627 		return ret;
628 
629 	return devm_mipi_dsi_attach(dev, ps_bridge->dsi);
630 }
631 
632 static int ps8640_probe(struct i2c_client *client)
633 {
634 	struct device *dev = &client->dev;
635 	struct ps8640 *ps_bridge;
636 	int ret;
637 	u32 i;
638 
639 	ps_bridge = devm_kzalloc(dev, sizeof(*ps_bridge), GFP_KERNEL);
640 	if (!ps_bridge)
641 		return -ENOMEM;
642 
643 	mutex_init(&ps_bridge->aux_lock);
644 
645 	ps_bridge->supplies[0].supply = "vdd12";
646 	ps_bridge->supplies[1].supply = "vdd33";
647 	ret = devm_regulator_bulk_get(dev, ARRAY_SIZE(ps_bridge->supplies),
648 				      ps_bridge->supplies);
649 	if (ret)
650 		return ret;
651 
652 	ps_bridge->gpio_powerdown = devm_gpiod_get(&client->dev, "powerdown",
653 						   GPIOD_OUT_HIGH);
654 	if (IS_ERR(ps_bridge->gpio_powerdown))
655 		return PTR_ERR(ps_bridge->gpio_powerdown);
656 
657 	/*
658 	 * Assert the reset to avoid the bridge being initialized prematurely
659 	 */
660 	ps_bridge->gpio_reset = devm_gpiod_get(&client->dev, "reset",
661 					       GPIOD_OUT_HIGH);
662 	if (IS_ERR(ps_bridge->gpio_reset))
663 		return PTR_ERR(ps_bridge->gpio_reset);
664 
665 	ps_bridge->bridge.funcs = &ps8640_bridge_funcs;
666 	ps_bridge->bridge.of_node = dev->of_node;
667 	ps_bridge->bridge.type = DRM_MODE_CONNECTOR_eDP;
668 
669 	/*
670 	 * Get MIPI DSI resources early. These can return -EPROBE_DEFER so
671 	 * we want to get them out of the way sooner.
672 	 */
673 	ret = ps8640_bridge_get_dsi_resources(&client->dev, ps_bridge);
674 	if (ret)
675 		return ret;
676 
677 	ps_bridge->page[PAGE0_DP_CNTL] = client;
678 
679 	ps_bridge->regmap[PAGE0_DP_CNTL] = devm_regmap_init_i2c(client, ps8640_regmap_config);
680 	if (IS_ERR(ps_bridge->regmap[PAGE0_DP_CNTL]))
681 		return PTR_ERR(ps_bridge->regmap[PAGE0_DP_CNTL]);
682 
683 	for (i = 1; i < ARRAY_SIZE(ps_bridge->page); i++) {
684 		ps_bridge->page[i] = devm_i2c_new_dummy_device(&client->dev,
685 							     client->adapter,
686 							     client->addr + i);
687 		if (IS_ERR(ps_bridge->page[i]))
688 			return PTR_ERR(ps_bridge->page[i]);
689 
690 		ps_bridge->regmap[i] = devm_regmap_init_i2c(ps_bridge->page[i],
691 							    ps8640_regmap_config + i);
692 		if (IS_ERR(ps_bridge->regmap[i]))
693 			return PTR_ERR(ps_bridge->regmap[i]);
694 	}
695 
696 	i2c_set_clientdata(client, ps_bridge);
697 
698 	ps_bridge->aux.name = "parade-ps8640-aux";
699 	ps_bridge->aux.dev = dev;
700 	ps_bridge->aux.transfer = ps8640_aux_transfer;
701 	ps_bridge->aux.wait_hpd_asserted = ps8640_wait_hpd_asserted;
702 	drm_dp_aux_init(&ps_bridge->aux);
703 
704 	pm_runtime_enable(dev);
705 	/*
706 	 * Powering on ps8640 takes ~300ms. To avoid wasting time on power
707 	 * cycling ps8640 too often, set autosuspend_delay to 2000ms to ensure
708 	 * the bridge wouldn't suspend in between each _aux_transfer_msg() call
709 	 * during EDID read (~20ms in my experiment) and in between the last
710 	 * _aux_transfer_msg() call during EDID read and the _pre_enable() call
711 	 * (~100ms in my experiment).
712 	 */
713 	pm_runtime_set_autosuspend_delay(dev, 2000);
714 	pm_runtime_use_autosuspend(dev);
715 	pm_suspend_ignore_children(dev, true);
716 	ret = devm_add_action_or_reset(dev, ps8640_runtime_disable, dev);
717 	if (ret)
718 		return ret;
719 
720 	ret = devm_of_dp_aux_populate_bus(&ps_bridge->aux, ps8640_bridge_link_panel);
721 
722 	/*
723 	 * If devm_of_dp_aux_populate_bus() returns -ENODEV then it's up to
724 	 * usa to call ps8640_bridge_link_panel() directly. NOTE: in this case
725 	 * the function is allowed to -EPROBE_DEFER.
726 	 */
727 	if (ret == -ENODEV)
728 		return ps8640_bridge_link_panel(&ps_bridge->aux);
729 
730 	return ret;
731 }
732 
733 static const struct of_device_id ps8640_match[] = {
734 	{ .compatible = "parade,ps8640" },
735 	{ }
736 };
737 MODULE_DEVICE_TABLE(of, ps8640_match);
738 
739 static struct i2c_driver ps8640_driver = {
740 	.probe = ps8640_probe,
741 	.driver = {
742 		.name = "ps8640",
743 		.of_match_table = ps8640_match,
744 		.pm = &ps8640_pm_ops,
745 	},
746 };
747 module_i2c_driver(ps8640_driver);
748 
749 MODULE_AUTHOR("Jitao Shi <jitao.shi@mediatek.com>");
750 MODULE_AUTHOR("CK Hu <ck.hu@mediatek.com>");
751 MODULE_AUTHOR("Enric Balletbo i Serra <enric.balletbo@collabora.com>");
752 MODULE_DESCRIPTION("PARADE ps8640 DSI-eDP converter driver");
753 MODULE_LICENSE("GPL v2");
754