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 	struct edid *edid;
109 	bool pre_enabled;
110 	bool need_post_hpd_delay;
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 bool ps8640_of_panel_on_aux_bus(struct device *dev)
159 {
160 	struct device_node *bus, *panel;
161 
162 	bus = of_get_child_by_name(dev->of_node, "aux-bus");
163 	if (!bus)
164 		return false;
165 
166 	panel = of_get_child_by_name(bus, "panel");
167 	of_node_put(bus);
168 	if (!panel)
169 		return false;
170 	of_node_put(panel);
171 
172 	return true;
173 }
174 
175 static int _ps8640_wait_hpd_asserted(struct ps8640 *ps_bridge, unsigned long wait_us)
176 {
177 	struct regmap *map = ps_bridge->regmap[PAGE2_TOP_CNTL];
178 	int status;
179 	int ret;
180 
181 	/*
182 	 * Apparently something about the firmware in the chip signals that
183 	 * HPD goes high by reporting GPIO9 as high (even though HPD isn't
184 	 * actually connected to GPIO9).
185 	 */
186 	ret = regmap_read_poll_timeout(map, PAGE2_GPIO_H, status,
187 				       status & PS_GPIO9, 20000, wait_us);
188 
189 	/*
190 	 * The first time we see HPD go high after a reset we delay an extra
191 	 * 50 ms. The best guess is that the MCU is doing "stuff" during this
192 	 * time (maybe talking to the panel) and we don't want to interrupt it.
193 	 *
194 	 * No locking is done around "need_post_hpd_delay". If we're here we
195 	 * know we're holding a PM Runtime reference and the only other place
196 	 * that touches this is PM Runtime resume.
197 	 */
198 	if (!ret && ps_bridge->need_post_hpd_delay) {
199 		ps_bridge->need_post_hpd_delay = false;
200 		msleep(50);
201 	}
202 
203 	return ret;
204 }
205 
206 static int ps8640_wait_hpd_asserted(struct drm_dp_aux *aux, unsigned long wait_us)
207 {
208 	struct ps8640 *ps_bridge = aux_to_ps8640(aux);
209 	struct device *dev = &ps_bridge->page[PAGE0_DP_CNTL]->dev;
210 	int ret;
211 
212 	/*
213 	 * Note that this function is called by code that has already powered
214 	 * the panel. We have to power ourselves up but we don't need to worry
215 	 * about powering the panel.
216 	 */
217 	pm_runtime_get_sync(dev);
218 	ret = _ps8640_wait_hpd_asserted(ps_bridge, wait_us);
219 	pm_runtime_mark_last_busy(dev);
220 	pm_runtime_put_autosuspend(dev);
221 
222 	return ret;
223 }
224 
225 static ssize_t ps8640_aux_transfer_msg(struct drm_dp_aux *aux,
226 				       struct drm_dp_aux_msg *msg)
227 {
228 	struct ps8640 *ps_bridge = aux_to_ps8640(aux);
229 	struct regmap *map = ps_bridge->regmap[PAGE0_DP_CNTL];
230 	struct device *dev = &ps_bridge->page[PAGE0_DP_CNTL]->dev;
231 	unsigned int len = msg->size;
232 	unsigned int data;
233 	unsigned int base;
234 	int ret;
235 	u8 request = msg->request &
236 		     ~(DP_AUX_I2C_MOT | DP_AUX_I2C_WRITE_STATUS_UPDATE);
237 	u8 *buf = msg->buffer;
238 	u8 addr_len[PAGE0_SWAUX_LENGTH + 1 - PAGE0_SWAUX_ADDR_7_0];
239 	u8 i;
240 	bool is_native_aux = false;
241 
242 	if (len > DP_AUX_MAX_PAYLOAD_BYTES)
243 		return -EINVAL;
244 
245 	if (msg->address & ~SWAUX_ADDR_MASK)
246 		return -EINVAL;
247 
248 	switch (request) {
249 	case DP_AUX_NATIVE_WRITE:
250 	case DP_AUX_NATIVE_READ:
251 		is_native_aux = true;
252 		fallthrough;
253 	case DP_AUX_I2C_WRITE:
254 	case DP_AUX_I2C_READ:
255 		break;
256 	default:
257 		return -EINVAL;
258 	}
259 
260 	ret = regmap_write(map, PAGE0_AUXCH_CFG3, AUXCH_CFG3_RESET);
261 	if (ret) {
262 		DRM_DEV_ERROR(dev, "failed to write PAGE0_AUXCH_CFG3: %d\n",
263 			      ret);
264 		return ret;
265 	}
266 
267 	/* Assume it's good */
268 	msg->reply = 0;
269 
270 	base = PAGE0_SWAUX_ADDR_7_0;
271 	addr_len[PAGE0_SWAUX_ADDR_7_0 - base] = msg->address;
272 	addr_len[PAGE0_SWAUX_ADDR_15_8 - base] = msg->address >> 8;
273 	addr_len[PAGE0_SWAUX_ADDR_23_16 - base] = (msg->address >> 16) |
274 						  (msg->request << 4);
275 	addr_len[PAGE0_SWAUX_LENGTH - base] = (len == 0) ? SWAUX_NO_PAYLOAD :
276 					      ((len - 1) & SWAUX_LENGTH_MASK);
277 
278 	regmap_bulk_write(map, PAGE0_SWAUX_ADDR_7_0, addr_len,
279 			  ARRAY_SIZE(addr_len));
280 
281 	if (len && (request == DP_AUX_NATIVE_WRITE ||
282 		    request == DP_AUX_I2C_WRITE)) {
283 		/* Write to the internal FIFO buffer */
284 		for (i = 0; i < len; i++) {
285 			ret = regmap_write(map, PAGE0_SWAUX_WDATA, buf[i]);
286 			if (ret) {
287 				DRM_DEV_ERROR(dev,
288 					      "failed to write WDATA: %d\n",
289 					      ret);
290 				return ret;
291 			}
292 		}
293 	}
294 
295 	regmap_write(map, PAGE0_SWAUX_CTRL, SWAUX_SEND);
296 
297 	/* Zero delay loop because i2c transactions are slow already */
298 	regmap_read_poll_timeout(map, PAGE0_SWAUX_CTRL, data,
299 				 !(data & SWAUX_SEND), 0, 50 * 1000);
300 
301 	regmap_read(map, PAGE0_SWAUX_STATUS, &data);
302 	if (ret) {
303 		DRM_DEV_ERROR(dev, "failed to read PAGE0_SWAUX_STATUS: %d\n",
304 			      ret);
305 		return ret;
306 	}
307 
308 	switch (data & SWAUX_STATUS_MASK) {
309 	case SWAUX_STATUS_NACK:
310 	case SWAUX_STATUS_I2C_NACK:
311 		/*
312 		 * The programming guide is not clear about whether a I2C NACK
313 		 * would trigger SWAUX_STATUS_NACK or SWAUX_STATUS_I2C_NACK. So
314 		 * we handle both cases together.
315 		 */
316 		if (is_native_aux)
317 			msg->reply |= DP_AUX_NATIVE_REPLY_NACK;
318 		else
319 			msg->reply |= DP_AUX_I2C_REPLY_NACK;
320 
321 		fallthrough;
322 	case SWAUX_STATUS_ACKM:
323 		len = data & SWAUX_M_MASK;
324 		break;
325 	case SWAUX_STATUS_DEFER:
326 	case SWAUX_STATUS_I2C_DEFER:
327 		if (is_native_aux)
328 			msg->reply |= DP_AUX_NATIVE_REPLY_DEFER;
329 		else
330 			msg->reply |= DP_AUX_I2C_REPLY_DEFER;
331 		len = data & SWAUX_M_MASK;
332 		break;
333 	case SWAUX_STATUS_INVALID:
334 		return -EOPNOTSUPP;
335 	case SWAUX_STATUS_TIMEOUT:
336 		return -ETIMEDOUT;
337 	}
338 
339 	if (len && (request == DP_AUX_NATIVE_READ ||
340 		    request == DP_AUX_I2C_READ)) {
341 		/* Read from the internal FIFO buffer */
342 		for (i = 0; i < len; i++) {
343 			ret = regmap_read(map, PAGE0_SWAUX_RDATA, &data);
344 			if (ret) {
345 				DRM_DEV_ERROR(dev,
346 					      "failed to read RDATA: %d\n",
347 					      ret);
348 				return ret;
349 			}
350 
351 			buf[i] = data;
352 		}
353 	}
354 
355 	return len;
356 }
357 
358 static ssize_t ps8640_aux_transfer(struct drm_dp_aux *aux,
359 				   struct drm_dp_aux_msg *msg)
360 {
361 	struct ps8640 *ps_bridge = aux_to_ps8640(aux);
362 	struct device *dev = &ps_bridge->page[PAGE0_DP_CNTL]->dev;
363 	int ret;
364 
365 	pm_runtime_get_sync(dev);
366 	ret = ps8640_aux_transfer_msg(aux, msg);
367 	pm_runtime_mark_last_busy(dev);
368 	pm_runtime_put_autosuspend(dev);
369 
370 	return ret;
371 }
372 
373 static void ps8640_bridge_vdo_control(struct ps8640 *ps_bridge,
374 				      const enum ps8640_vdo_control ctrl)
375 {
376 	struct regmap *map = ps_bridge->regmap[PAGE3_DSI_CNTL1];
377 	struct device *dev = &ps_bridge->page[PAGE3_DSI_CNTL1]->dev;
378 	u8 vdo_ctrl_buf[] = { VDO_CTL_ADD, ctrl };
379 	int ret;
380 
381 	ret = regmap_bulk_write(map, PAGE3_SET_ADD,
382 				vdo_ctrl_buf, sizeof(vdo_ctrl_buf));
383 
384 	if (ret < 0)
385 		dev_err(dev, "failed to %sable VDO: %d\n",
386 			ctrl == ENABLE ? "en" : "dis", ret);
387 }
388 
389 static int __maybe_unused ps8640_resume(struct device *dev)
390 {
391 	struct ps8640 *ps_bridge = dev_get_drvdata(dev);
392 	int ret;
393 
394 	ret = regulator_bulk_enable(ARRAY_SIZE(ps_bridge->supplies),
395 				    ps_bridge->supplies);
396 	if (ret < 0) {
397 		dev_err(dev, "cannot enable regulators %d\n", ret);
398 		return ret;
399 	}
400 
401 	gpiod_set_value(ps_bridge->gpio_powerdown, 0);
402 	gpiod_set_value(ps_bridge->gpio_reset, 1);
403 	usleep_range(2000, 2500);
404 	gpiod_set_value(ps_bridge->gpio_reset, 0);
405 	/* Double reset for T4 and T5 */
406 	msleep(50);
407 	gpiod_set_value(ps_bridge->gpio_reset, 1);
408 	msleep(50);
409 	gpiod_set_value(ps_bridge->gpio_reset, 0);
410 
411 	/* We just reset things, so we need a delay after the first HPD */
412 	ps_bridge->need_post_hpd_delay = true;
413 
414 	/*
415 	 * Mystery 200 ms delay for the "MCU to be ready". It's unclear if
416 	 * this is truly necessary since the MCU will already signal that
417 	 * things are "good to go" by signaling HPD on "gpio 9". See
418 	 * _ps8640_wait_hpd_asserted(). For now we'll keep this mystery delay
419 	 * just in case.
420 	 */
421 	msleep(200);
422 
423 	return 0;
424 }
425 
426 static int __maybe_unused ps8640_suspend(struct device *dev)
427 {
428 	struct ps8640 *ps_bridge = dev_get_drvdata(dev);
429 	int ret;
430 
431 	gpiod_set_value(ps_bridge->gpio_reset, 1);
432 	gpiod_set_value(ps_bridge->gpio_powerdown, 1);
433 	ret = regulator_bulk_disable(ARRAY_SIZE(ps_bridge->supplies),
434 				     ps_bridge->supplies);
435 	if (ret < 0)
436 		dev_err(dev, "cannot disable regulators %d\n", ret);
437 
438 	return ret;
439 }
440 
441 static const struct dev_pm_ops ps8640_pm_ops = {
442 	SET_RUNTIME_PM_OPS(ps8640_suspend, ps8640_resume, NULL)
443 	SET_SYSTEM_SLEEP_PM_OPS(pm_runtime_force_suspend,
444 				pm_runtime_force_resume)
445 };
446 
447 static void ps8640_atomic_pre_enable(struct drm_bridge *bridge,
448 				     struct drm_bridge_state *old_bridge_state)
449 {
450 	struct ps8640 *ps_bridge = bridge_to_ps8640(bridge);
451 	struct regmap *map = ps_bridge->regmap[PAGE2_TOP_CNTL];
452 	struct device *dev = &ps_bridge->page[PAGE0_DP_CNTL]->dev;
453 	int ret;
454 
455 	pm_runtime_get_sync(dev);
456 	ret = _ps8640_wait_hpd_asserted(ps_bridge, 200 * 1000);
457 	if (ret < 0)
458 		dev_warn(dev, "HPD didn't go high: %d\n", ret);
459 
460 	/*
461 	 * The Manufacturer Command Set (MCS) is a device dependent interface
462 	 * intended for factory programming of the display module default
463 	 * parameters. Once the display module is configured, the MCS shall be
464 	 * disabled by the manufacturer. Once disabled, all MCS commands are
465 	 * ignored by the display interface.
466 	 */
467 
468 	ret = regmap_update_bits(map, PAGE2_MCS_EN, MCS_EN, 0);
469 	if (ret < 0)
470 		dev_warn(dev, "failed write PAGE2_MCS_EN: %d\n", ret);
471 
472 	/* Switch access edp panel's edid through i2c */
473 	ret = regmap_write(map, PAGE2_I2C_BYPASS, I2C_BYPASS_EN);
474 	if (ret < 0)
475 		dev_warn(dev, "failed write PAGE2_MCS_EN: %d\n", ret);
476 
477 	ps8640_bridge_vdo_control(ps_bridge, ENABLE);
478 
479 	ps_bridge->pre_enabled = true;
480 }
481 
482 static void ps8640_atomic_post_disable(struct drm_bridge *bridge,
483 				       struct drm_bridge_state *old_bridge_state)
484 {
485 	struct ps8640 *ps_bridge = bridge_to_ps8640(bridge);
486 
487 	ps_bridge->pre_enabled = false;
488 
489 	ps8640_bridge_vdo_control(ps_bridge, DISABLE);
490 	pm_runtime_put_sync_suspend(&ps_bridge->page[PAGE0_DP_CNTL]->dev);
491 }
492 
493 static int ps8640_bridge_attach(struct drm_bridge *bridge,
494 				enum drm_bridge_attach_flags flags)
495 {
496 	struct ps8640 *ps_bridge = bridge_to_ps8640(bridge);
497 	struct device *dev = &ps_bridge->page[0]->dev;
498 	int ret;
499 
500 	if (!(flags & DRM_BRIDGE_ATTACH_NO_CONNECTOR))
501 		return -EINVAL;
502 
503 	ps_bridge->aux.drm_dev = bridge->dev;
504 	ret = drm_dp_aux_register(&ps_bridge->aux);
505 	if (ret) {
506 		dev_err(dev, "failed to register DP AUX channel: %d\n", ret);
507 		return ret;
508 	}
509 
510 	ps_bridge->link = device_link_add(bridge->dev->dev, dev, DL_FLAG_STATELESS);
511 	if (!ps_bridge->link) {
512 		dev_err(dev, "failed to create device link");
513 		ret = -EINVAL;
514 		goto err_devlink;
515 	}
516 
517 	/* Attach the panel-bridge to the dsi bridge */
518 	ret = drm_bridge_attach(bridge->encoder, ps_bridge->panel_bridge,
519 				&ps_bridge->bridge, flags);
520 	if (ret)
521 		goto err_bridge_attach;
522 
523 	return 0;
524 
525 err_bridge_attach:
526 	device_link_del(ps_bridge->link);
527 err_devlink:
528 	drm_dp_aux_unregister(&ps_bridge->aux);
529 
530 	return ret;
531 }
532 
533 static void ps8640_bridge_detach(struct drm_bridge *bridge)
534 {
535 	struct ps8640 *ps_bridge = bridge_to_ps8640(bridge);
536 
537 	drm_dp_aux_unregister(&ps_bridge->aux);
538 	if (ps_bridge->link)
539 		device_link_del(ps_bridge->link);
540 }
541 
542 static struct edid *ps8640_bridge_get_edid(struct drm_bridge *bridge,
543 					   struct drm_connector *connector)
544 {
545 	struct ps8640 *ps_bridge = bridge_to_ps8640(bridge);
546 	struct device *dev = &ps_bridge->page[PAGE0_DP_CNTL]->dev;
547 	bool poweroff = !ps_bridge->pre_enabled;
548 
549 	if (!ps_bridge->edid) {
550 		/*
551 		 * When we end calling get_edid() triggered by an ioctl, i.e
552 		 *
553 		 *   drm_mode_getconnector (ioctl)
554 		 *     -> drm_helper_probe_single_connector_modes
555 		 *        -> drm_bridge_connector_get_modes
556 		 *           -> ps8640_bridge_get_edid
557 		 *
558 		 * We need to make sure that what we need is enabled before
559 		 * reading EDID, for this chip, we need to do a full poweron,
560 		 * otherwise it will fail.
561 		 */
562 		if (poweroff)
563 			drm_atomic_bridge_chain_pre_enable(bridge,
564 							   connector->state->state);
565 
566 		ps_bridge->edid = drm_get_edid(connector,
567 					       ps_bridge->page[PAGE0_DP_CNTL]->adapter);
568 
569 		/*
570 		 * If we call the get_edid() function without having enabled the
571 		 * chip before, return the chip to its original power state.
572 		 */
573 		if (poweroff)
574 			drm_atomic_bridge_chain_post_disable(bridge,
575 							     connector->state->state);
576 	}
577 
578 	if (!ps_bridge->edid) {
579 		dev_err(dev, "Failed to get EDID\n");
580 		return NULL;
581 	}
582 
583 	return drm_edid_duplicate(ps_bridge->edid);
584 }
585 
586 static void ps8640_runtime_disable(void *data)
587 {
588 	pm_runtime_dont_use_autosuspend(data);
589 	pm_runtime_disable(data);
590 }
591 
592 static const struct drm_bridge_funcs ps8640_bridge_funcs = {
593 	.attach = ps8640_bridge_attach,
594 	.detach = ps8640_bridge_detach,
595 	.get_edid = ps8640_bridge_get_edid,
596 	.atomic_post_disable = ps8640_atomic_post_disable,
597 	.atomic_pre_enable = ps8640_atomic_pre_enable,
598 	.atomic_duplicate_state = drm_atomic_helper_bridge_duplicate_state,
599 	.atomic_destroy_state = drm_atomic_helper_bridge_destroy_state,
600 	.atomic_reset = drm_atomic_helper_bridge_reset,
601 };
602 
603 static int ps8640_bridge_get_dsi_resources(struct device *dev, struct ps8640 *ps_bridge)
604 {
605 	struct device_node *in_ep, *dsi_node;
606 	struct mipi_dsi_device *dsi;
607 	struct mipi_dsi_host *host;
608 	const struct mipi_dsi_device_info info = { .type = "ps8640",
609 						   .channel = 0,
610 						   .node = NULL,
611 						 };
612 
613 	/* port@0 is ps8640 dsi input port */
614 	in_ep = of_graph_get_endpoint_by_regs(dev->of_node, 0, -1);
615 	if (!in_ep)
616 		return -ENODEV;
617 
618 	dsi_node = of_graph_get_remote_port_parent(in_ep);
619 	of_node_put(in_ep);
620 	if (!dsi_node)
621 		return -ENODEV;
622 
623 	host = of_find_mipi_dsi_host_by_node(dsi_node);
624 	of_node_put(dsi_node);
625 	if (!host)
626 		return -EPROBE_DEFER;
627 
628 	dsi = devm_mipi_dsi_device_register_full(dev, host, &info);
629 	if (IS_ERR(dsi)) {
630 		dev_err(dev, "failed to create dsi device\n");
631 		return PTR_ERR(dsi);
632 	}
633 
634 	ps_bridge->dsi = dsi;
635 
636 	dsi->host = host;
637 	dsi->mode_flags = MIPI_DSI_MODE_VIDEO |
638 			  MIPI_DSI_MODE_VIDEO_SYNC_PULSE;
639 	dsi->format = MIPI_DSI_FMT_RGB888;
640 	dsi->lanes = NUM_MIPI_LANES;
641 
642 	return 0;
643 }
644 
645 static int ps8640_bridge_link_panel(struct drm_dp_aux *aux)
646 {
647 	struct ps8640 *ps_bridge = aux_to_ps8640(aux);
648 	struct device *dev = aux->dev;
649 	struct device_node *np = dev->of_node;
650 	int ret;
651 
652 	/*
653 	 * NOTE about returning -EPROBE_DEFER from this function: if we
654 	 * return an error (most relevant to -EPROBE_DEFER) it will only
655 	 * be passed out to ps8640_probe() if it called this directly (AKA the
656 	 * panel isn't under the "aux-bus" node). That should be fine because
657 	 * if the panel is under "aux-bus" it's guaranteed to have probed by
658 	 * the time this function has been called.
659 	 */
660 
661 	/* port@1 is ps8640 output port */
662 	ps_bridge->panel_bridge = devm_drm_of_get_bridge(dev, np, 1, 0);
663 	if (IS_ERR(ps_bridge->panel_bridge))
664 		return PTR_ERR(ps_bridge->panel_bridge);
665 
666 	ret = devm_drm_bridge_add(dev, &ps_bridge->bridge);
667 	if (ret)
668 		return ret;
669 
670 	return devm_mipi_dsi_attach(dev, ps_bridge->dsi);
671 }
672 
673 static int ps8640_probe(struct i2c_client *client)
674 {
675 	struct device *dev = &client->dev;
676 	struct ps8640 *ps_bridge;
677 	int ret;
678 	u32 i;
679 
680 	ps_bridge = devm_kzalloc(dev, sizeof(*ps_bridge), GFP_KERNEL);
681 	if (!ps_bridge)
682 		return -ENOMEM;
683 
684 	ps_bridge->supplies[0].supply = "vdd12";
685 	ps_bridge->supplies[1].supply = "vdd33";
686 	ret = devm_regulator_bulk_get(dev, ARRAY_SIZE(ps_bridge->supplies),
687 				      ps_bridge->supplies);
688 	if (ret)
689 		return ret;
690 
691 	ps_bridge->gpio_powerdown = devm_gpiod_get(&client->dev, "powerdown",
692 						   GPIOD_OUT_HIGH);
693 	if (IS_ERR(ps_bridge->gpio_powerdown))
694 		return PTR_ERR(ps_bridge->gpio_powerdown);
695 
696 	/*
697 	 * Assert the reset to avoid the bridge being initialized prematurely
698 	 */
699 	ps_bridge->gpio_reset = devm_gpiod_get(&client->dev, "reset",
700 					       GPIOD_OUT_HIGH);
701 	if (IS_ERR(ps_bridge->gpio_reset))
702 		return PTR_ERR(ps_bridge->gpio_reset);
703 
704 	ps_bridge->bridge.funcs = &ps8640_bridge_funcs;
705 	ps_bridge->bridge.of_node = dev->of_node;
706 	ps_bridge->bridge.type = DRM_MODE_CONNECTOR_eDP;
707 
708 	/*
709 	 * In the device tree, if panel is listed under aux-bus of the bridge
710 	 * node, panel driver should be able to retrieve EDID by itself using
711 	 * aux-bus. So let's not set DRM_BRIDGE_OP_EDID here.
712 	 */
713 	if (!ps8640_of_panel_on_aux_bus(&client->dev))
714 		ps_bridge->bridge.ops = DRM_BRIDGE_OP_EDID;
715 
716 	/*
717 	 * Get MIPI DSI resources early. These can return -EPROBE_DEFER so
718 	 * we want to get them out of the way sooner.
719 	 */
720 	ret = ps8640_bridge_get_dsi_resources(&client->dev, ps_bridge);
721 	if (ret)
722 		return ret;
723 
724 	ps_bridge->page[PAGE0_DP_CNTL] = client;
725 
726 	ps_bridge->regmap[PAGE0_DP_CNTL] = devm_regmap_init_i2c(client, ps8640_regmap_config);
727 	if (IS_ERR(ps_bridge->regmap[PAGE0_DP_CNTL]))
728 		return PTR_ERR(ps_bridge->regmap[PAGE0_DP_CNTL]);
729 
730 	for (i = 1; i < ARRAY_SIZE(ps_bridge->page); i++) {
731 		ps_bridge->page[i] = devm_i2c_new_dummy_device(&client->dev,
732 							     client->adapter,
733 							     client->addr + i);
734 		if (IS_ERR(ps_bridge->page[i]))
735 			return PTR_ERR(ps_bridge->page[i]);
736 
737 		ps_bridge->regmap[i] = devm_regmap_init_i2c(ps_bridge->page[i],
738 							    ps8640_regmap_config + i);
739 		if (IS_ERR(ps_bridge->regmap[i]))
740 			return PTR_ERR(ps_bridge->regmap[i]);
741 	}
742 
743 	i2c_set_clientdata(client, ps_bridge);
744 
745 	ps_bridge->aux.name = "parade-ps8640-aux";
746 	ps_bridge->aux.dev = dev;
747 	ps_bridge->aux.transfer = ps8640_aux_transfer;
748 	ps_bridge->aux.wait_hpd_asserted = ps8640_wait_hpd_asserted;
749 	drm_dp_aux_init(&ps_bridge->aux);
750 
751 	pm_runtime_enable(dev);
752 	/*
753 	 * Powering on ps8640 takes ~300ms. To avoid wasting time on power
754 	 * cycling ps8640 too often, set autosuspend_delay to 2000ms to ensure
755 	 * the bridge wouldn't suspend in between each _aux_transfer_msg() call
756 	 * during EDID read (~20ms in my experiment) and in between the last
757 	 * _aux_transfer_msg() call during EDID read and the _pre_enable() call
758 	 * (~100ms in my experiment).
759 	 */
760 	pm_runtime_set_autosuspend_delay(dev, 2000);
761 	pm_runtime_use_autosuspend(dev);
762 	pm_suspend_ignore_children(dev, true);
763 	ret = devm_add_action_or_reset(dev, ps8640_runtime_disable, dev);
764 	if (ret)
765 		return ret;
766 
767 	ret = devm_of_dp_aux_populate_bus(&ps_bridge->aux, ps8640_bridge_link_panel);
768 
769 	/*
770 	 * If devm_of_dp_aux_populate_bus() returns -ENODEV then it's up to
771 	 * usa to call ps8640_bridge_link_panel() directly. NOTE: in this case
772 	 * the function is allowed to -EPROBE_DEFER.
773 	 */
774 	if (ret == -ENODEV)
775 		return ps8640_bridge_link_panel(&ps_bridge->aux);
776 
777 	return ret;
778 }
779 
780 static void ps8640_remove(struct i2c_client *client)
781 {
782 	struct ps8640 *ps_bridge = i2c_get_clientdata(client);
783 
784 	kfree(ps_bridge->edid);
785 }
786 
787 static const struct of_device_id ps8640_match[] = {
788 	{ .compatible = "parade,ps8640" },
789 	{ }
790 };
791 MODULE_DEVICE_TABLE(of, ps8640_match);
792 
793 static struct i2c_driver ps8640_driver = {
794 	.probe = ps8640_probe,
795 	.remove = ps8640_remove,
796 	.driver = {
797 		.name = "ps8640",
798 		.of_match_table = ps8640_match,
799 		.pm = &ps8640_pm_ops,
800 	},
801 };
802 module_i2c_driver(ps8640_driver);
803 
804 MODULE_AUTHOR("Jitao Shi <jitao.shi@mediatek.com>");
805 MODULE_AUTHOR("CK Hu <ck.hu@mediatek.com>");
806 MODULE_AUTHOR("Enric Balletbo i Serra <enric.balletbo@collabora.com>");
807 MODULE_DESCRIPTION("PARADE ps8640 DSI-eDP converter driver");
808 MODULE_LICENSE("GPL v2");
809