xref: /linux/drivers/gpu/drm/i915/gvt/edid.c (revision 3fd6c59042dbba50391e30862beac979491145fe)
1 /*
2  * Copyright(c) 2011-2016 Intel Corporation. All rights reserved.
3  *
4  * Permission is hereby granted, free of charge, to any person obtaining a
5  * copy of this software and associated documentation files (the "Software"),
6  * to deal in the Software without restriction, including without limitation
7  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
8  * and/or sell copies of the Software, and to permit persons to whom the
9  * Software is furnished to do so, subject to the following conditions:
10  *
11  * The above copyright notice and this permission notice (including the next
12  * paragraph) shall be included in all copies or substantial portions of the
13  * Software.
14  *
15  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
16  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
17  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
18  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
19  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
20  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
21  * SOFTWARE.
22  *
23  * Authors:
24  *    Ke Yu
25  *    Zhiyuan Lv <zhiyuan.lv@intel.com>
26  *
27  * Contributors:
28  *    Terrence Xu <terrence.xu@intel.com>
29  *    Changbin Du <changbin.du@intel.com>
30  *    Bing Niu <bing.niu@intel.com>
31  *    Zhi Wang <zhi.a.wang@intel.com>
32  *
33  */
34 
35 #include <drm/display/drm_dp.h>
36 
37 #include "display/intel_dp_aux_regs.h"
38 #include "display/intel_gmbus_regs.h"
39 #include "gvt.h"
40 #include "i915_drv.h"
41 #include "i915_reg.h"
42 
43 #define GMBUS1_TOTAL_BYTES_SHIFT 16
44 #define GMBUS1_TOTAL_BYTES_MASK 0x1ff
45 #define gmbus1_total_byte_count(v) (((v) >> \
46 	GMBUS1_TOTAL_BYTES_SHIFT) & GMBUS1_TOTAL_BYTES_MASK)
47 #define gmbus1_target_addr(v) (((v) & 0xff) >> 1)
48 #define gmbus1_target_index(v) (((v) >> 8) & 0xff)
49 #define gmbus1_bus_cycle(v) (((v) >> 25) & 0x7)
50 
51 /* GMBUS0 bits definitions */
52 #define _GMBUS_PIN_SEL_MASK     (0x7)
53 
edid_get_byte(struct intel_vgpu * vgpu)54 static unsigned char edid_get_byte(struct intel_vgpu *vgpu)
55 {
56 	struct intel_vgpu_i2c_edid *edid = &vgpu->display.i2c_edid;
57 	unsigned char chr = 0;
58 
59 	if (edid->state == I2C_NOT_SPECIFIED || !edid->target_selected) {
60 		gvt_vgpu_err("Driver tries to read EDID without proper sequence!\n");
61 		return 0;
62 	}
63 	if (edid->current_edid_read >= EDID_SIZE) {
64 		gvt_vgpu_err("edid_get_byte() exceeds the size of EDID!\n");
65 		return 0;
66 	}
67 
68 	if (!edid->edid_available) {
69 		gvt_vgpu_err("Reading EDID but EDID is not available!\n");
70 		return 0;
71 	}
72 
73 	if (intel_vgpu_has_monitor_on_port(vgpu, edid->port)) {
74 		struct intel_vgpu_edid_data *edid_data =
75 			intel_vgpu_port(vgpu, edid->port)->edid;
76 
77 		chr = edid_data->edid_block[edid->current_edid_read];
78 		edid->current_edid_read++;
79 	} else {
80 		gvt_vgpu_err("No EDID available during the reading?\n");
81 	}
82 	return chr;
83 }
84 
cnp_get_port_from_gmbus0(u32 gmbus0)85 static inline int cnp_get_port_from_gmbus0(u32 gmbus0)
86 {
87 	int port_select = gmbus0 & _GMBUS_PIN_SEL_MASK;
88 	int port = -EINVAL;
89 
90 	if (port_select == GMBUS_PIN_1_BXT)
91 		port = PORT_B;
92 	else if (port_select == GMBUS_PIN_2_BXT)
93 		port = PORT_C;
94 	else if (port_select == GMBUS_PIN_3_BXT)
95 		port = PORT_D;
96 	else if (port_select == GMBUS_PIN_4_CNP)
97 		port = PORT_E;
98 	return port;
99 }
100 
bxt_get_port_from_gmbus0(u32 gmbus0)101 static inline int bxt_get_port_from_gmbus0(u32 gmbus0)
102 {
103 	int port_select = gmbus0 & _GMBUS_PIN_SEL_MASK;
104 	int port = -EINVAL;
105 
106 	if (port_select == GMBUS_PIN_1_BXT)
107 		port = PORT_B;
108 	else if (port_select == GMBUS_PIN_2_BXT)
109 		port = PORT_C;
110 	else if (port_select == GMBUS_PIN_3_BXT)
111 		port = PORT_D;
112 	return port;
113 }
114 
get_port_from_gmbus0(u32 gmbus0)115 static inline int get_port_from_gmbus0(u32 gmbus0)
116 {
117 	int port_select = gmbus0 & _GMBUS_PIN_SEL_MASK;
118 	int port = -EINVAL;
119 
120 	if (port_select == GMBUS_PIN_VGADDC)
121 		port = PORT_E;
122 	else if (port_select == GMBUS_PIN_DPC)
123 		port = PORT_C;
124 	else if (port_select == GMBUS_PIN_DPB)
125 		port = PORT_B;
126 	else if (port_select == GMBUS_PIN_DPD)
127 		port = PORT_D;
128 	return port;
129 }
130 
reset_gmbus_controller(struct intel_vgpu * vgpu)131 static void reset_gmbus_controller(struct intel_vgpu *vgpu)
132 {
133 	vgpu_vreg_t(vgpu, PCH_GMBUS2) = GMBUS_HW_RDY;
134 	if (!vgpu->display.i2c_edid.edid_available)
135 		vgpu_vreg_t(vgpu, PCH_GMBUS2) |= GMBUS_SATOER;
136 	vgpu->display.i2c_edid.gmbus.phase = GMBUS_IDLE_PHASE;
137 }
138 
139 /* GMBUS0 */
gmbus0_mmio_write(struct intel_vgpu * vgpu,unsigned int offset,void * p_data,unsigned int bytes)140 static int gmbus0_mmio_write(struct intel_vgpu *vgpu,
141 			unsigned int offset, void *p_data, unsigned int bytes)
142 {
143 	struct drm_i915_private *i915 = vgpu->gvt->gt->i915;
144 	int port, pin_select;
145 
146 	memcpy(&vgpu_vreg(vgpu, offset), p_data, bytes);
147 
148 	pin_select = vgpu_vreg(vgpu, offset) & _GMBUS_PIN_SEL_MASK;
149 
150 	intel_vgpu_init_i2c_edid(vgpu);
151 
152 	if (pin_select == 0)
153 		return 0;
154 
155 	if (IS_BROXTON(i915))
156 		port = bxt_get_port_from_gmbus0(pin_select);
157 	else if (IS_COFFEELAKE(i915) || IS_COMETLAKE(i915))
158 		port = cnp_get_port_from_gmbus0(pin_select);
159 	else
160 		port = get_port_from_gmbus0(pin_select);
161 	if (drm_WARN_ON(&i915->drm, port < 0))
162 		return 0;
163 
164 	vgpu->display.i2c_edid.state = I2C_GMBUS;
165 	vgpu->display.i2c_edid.gmbus.phase = GMBUS_IDLE_PHASE;
166 
167 	vgpu_vreg_t(vgpu, PCH_GMBUS2) &= ~GMBUS_ACTIVE;
168 	vgpu_vreg_t(vgpu, PCH_GMBUS2) |= GMBUS_HW_RDY | GMBUS_HW_WAIT_PHASE;
169 
170 	if (intel_vgpu_has_monitor_on_port(vgpu, port) &&
171 			!intel_vgpu_port_is_dp(vgpu, port)) {
172 		vgpu->display.i2c_edid.port = port;
173 		vgpu->display.i2c_edid.edid_available = true;
174 		vgpu_vreg_t(vgpu, PCH_GMBUS2) &= ~GMBUS_SATOER;
175 	} else
176 		vgpu_vreg_t(vgpu, PCH_GMBUS2) |= GMBUS_SATOER;
177 	return 0;
178 }
179 
gmbus1_mmio_write(struct intel_vgpu * vgpu,unsigned int offset,void * p_data,unsigned int bytes)180 static int gmbus1_mmio_write(struct intel_vgpu *vgpu, unsigned int offset,
181 		void *p_data, unsigned int bytes)
182 {
183 	struct intel_vgpu_i2c_edid *i2c_edid = &vgpu->display.i2c_edid;
184 	u32 target_addr;
185 	u32 wvalue = *(u32 *)p_data;
186 
187 	if (vgpu_vreg(vgpu, offset) & GMBUS_SW_CLR_INT) {
188 		if (!(wvalue & GMBUS_SW_CLR_INT)) {
189 			vgpu_vreg(vgpu, offset) &= ~GMBUS_SW_CLR_INT;
190 			reset_gmbus_controller(vgpu);
191 		}
192 		/*
193 		 * TODO: "This bit is cleared to zero when an event
194 		 * causes the HW_RDY bit transition to occur "
195 		 */
196 	} else {
197 		/*
198 		 * per bspec setting this bit can cause:
199 		 * 1) INT status bit cleared
200 		 * 2) HW_RDY bit asserted
201 		 */
202 		if (wvalue & GMBUS_SW_CLR_INT) {
203 			vgpu_vreg_t(vgpu, PCH_GMBUS2) &= ~GMBUS_INT;
204 			vgpu_vreg_t(vgpu, PCH_GMBUS2) |= GMBUS_HW_RDY;
205 		}
206 
207 		/* For virtualization, we suppose that HW is always ready,
208 		 * so GMBUS_SW_RDY should always be cleared
209 		 */
210 		if (wvalue & GMBUS_SW_RDY)
211 			wvalue &= ~GMBUS_SW_RDY;
212 
213 		i2c_edid->gmbus.total_byte_count =
214 			gmbus1_total_byte_count(wvalue);
215 		target_addr = gmbus1_target_addr(wvalue);
216 
217 		/* vgpu gmbus only support EDID */
218 		if (target_addr == EDID_ADDR) {
219 			i2c_edid->target_selected = true;
220 		} else if (target_addr != 0) {
221 			gvt_dbg_dpy(
222 				"vgpu%d: unsupported gmbus target addr(0x%x)\n"
223 				"	gmbus operations will be ignored.\n",
224 					vgpu->id, target_addr);
225 		}
226 
227 		if (wvalue & GMBUS_CYCLE_INDEX)
228 			i2c_edid->current_edid_read =
229 				gmbus1_target_index(wvalue);
230 
231 		i2c_edid->gmbus.cycle_type = gmbus1_bus_cycle(wvalue);
232 		switch (gmbus1_bus_cycle(wvalue)) {
233 		case GMBUS_NOCYCLE:
234 			break;
235 		case GMBUS_STOP:
236 			/* From spec:
237 			 * This can only cause a STOP to be generated
238 			 * if a GMBUS cycle is generated, the GMBUS is
239 			 * currently in a data/wait/idle phase, or it is in a
240 			 * WAIT phase
241 			 */
242 			if (gmbus1_bus_cycle(vgpu_vreg(vgpu, offset))
243 				!= GMBUS_NOCYCLE) {
244 				intel_vgpu_init_i2c_edid(vgpu);
245 				/* After the 'stop' cycle, hw state would become
246 				 * 'stop phase' and then 'idle phase' after a
247 				 * few milliseconds. In emulation, we just set
248 				 * it as 'idle phase' ('stop phase' is not
249 				 * visible in gmbus interface)
250 				 */
251 				i2c_edid->gmbus.phase = GMBUS_IDLE_PHASE;
252 				vgpu_vreg_t(vgpu, PCH_GMBUS2) &= ~GMBUS_ACTIVE;
253 			}
254 			break;
255 		case NIDX_NS_W:
256 		case IDX_NS_W:
257 		case NIDX_STOP:
258 		case IDX_STOP:
259 			/* From hw spec the GMBUS phase
260 			 * transition like this:
261 			 * START (-->INDEX) -->DATA
262 			 */
263 			i2c_edid->gmbus.phase = GMBUS_DATA_PHASE;
264 			vgpu_vreg_t(vgpu, PCH_GMBUS2) |= GMBUS_ACTIVE;
265 			break;
266 		default:
267 			gvt_vgpu_err("Unknown/reserved GMBUS cycle detected!\n");
268 			break;
269 		}
270 		/*
271 		 * From hw spec the WAIT state will be
272 		 * cleared:
273 		 * (1) in a new GMBUS cycle
274 		 * (2) by generating a stop
275 		 */
276 		vgpu_vreg(vgpu, offset) = wvalue;
277 	}
278 	return 0;
279 }
280 
gmbus3_mmio_write(struct intel_vgpu * vgpu,unsigned int offset,void * p_data,unsigned int bytes)281 static int gmbus3_mmio_write(struct intel_vgpu *vgpu, unsigned int offset,
282 	void *p_data, unsigned int bytes)
283 {
284 	struct drm_i915_private *i915 = vgpu->gvt->gt->i915;
285 
286 	drm_WARN_ON(&i915->drm, 1);
287 	return 0;
288 }
289 
gmbus3_mmio_read(struct intel_vgpu * vgpu,unsigned int offset,void * p_data,unsigned int bytes)290 static int gmbus3_mmio_read(struct intel_vgpu *vgpu, unsigned int offset,
291 		void *p_data, unsigned int bytes)
292 {
293 	int i;
294 	unsigned char byte_data;
295 	struct intel_vgpu_i2c_edid *i2c_edid = &vgpu->display.i2c_edid;
296 	int byte_left = i2c_edid->gmbus.total_byte_count -
297 				i2c_edid->current_edid_read;
298 	int byte_count = byte_left;
299 	u32 reg_data = 0;
300 
301 	/* Data can only be recevied if previous settings correct */
302 	if (vgpu_vreg_t(vgpu, PCH_GMBUS1) & GMBUS_SLAVE_READ) {
303 		if (byte_left <= 0) {
304 			memcpy(p_data, &vgpu_vreg(vgpu, offset), bytes);
305 			return 0;
306 		}
307 
308 		if (byte_count > 4)
309 			byte_count = 4;
310 		for (i = 0; i < byte_count; i++) {
311 			byte_data = edid_get_byte(vgpu);
312 			reg_data |= (byte_data << (i << 3));
313 		}
314 
315 		memcpy(&vgpu_vreg(vgpu, offset), &reg_data, byte_count);
316 		memcpy(p_data, &vgpu_vreg(vgpu, offset), bytes);
317 
318 		if (byte_left <= 4) {
319 			switch (i2c_edid->gmbus.cycle_type) {
320 			case NIDX_STOP:
321 			case IDX_STOP:
322 				i2c_edid->gmbus.phase = GMBUS_IDLE_PHASE;
323 				break;
324 			case NIDX_NS_W:
325 			case IDX_NS_W:
326 			default:
327 				i2c_edid->gmbus.phase = GMBUS_WAIT_PHASE;
328 				break;
329 			}
330 			intel_vgpu_init_i2c_edid(vgpu);
331 		}
332 		/*
333 		 * Read GMBUS3 during send operation,
334 		 * return the latest written value
335 		 */
336 	} else {
337 		memcpy(p_data, &vgpu_vreg(vgpu, offset), bytes);
338 		gvt_vgpu_err("warning: gmbus3 read with nothing returned\n");
339 	}
340 	return 0;
341 }
342 
gmbus2_mmio_read(struct intel_vgpu * vgpu,unsigned int offset,void * p_data,unsigned int bytes)343 static int gmbus2_mmio_read(struct intel_vgpu *vgpu, unsigned int offset,
344 		void *p_data, unsigned int bytes)
345 {
346 	u32 value = vgpu_vreg(vgpu, offset);
347 
348 	if (!(vgpu_vreg(vgpu, offset) & GMBUS_INUSE))
349 		vgpu_vreg(vgpu, offset) |= GMBUS_INUSE;
350 	memcpy(p_data, (void *)&value, bytes);
351 	return 0;
352 }
353 
gmbus2_mmio_write(struct intel_vgpu * vgpu,unsigned int offset,void * p_data,unsigned int bytes)354 static int gmbus2_mmio_write(struct intel_vgpu *vgpu, unsigned int offset,
355 		void *p_data, unsigned int bytes)
356 {
357 	u32 wvalue = *(u32 *)p_data;
358 
359 	if (wvalue & GMBUS_INUSE)
360 		vgpu_vreg(vgpu, offset) &= ~GMBUS_INUSE;
361 	/* All other bits are read-only */
362 	return 0;
363 }
364 
365 /**
366  * intel_gvt_i2c_handle_gmbus_read - emulate gmbus register mmio read
367  * @vgpu: a vGPU
368  * @offset: reg offset
369  * @p_data: data return buffer
370  * @bytes: access data length
371  *
372  * This function is used to emulate gmbus register mmio read
373  *
374  * Returns:
375  * Zero on success, negative error code if failed.
376  *
377  */
intel_gvt_i2c_handle_gmbus_read(struct intel_vgpu * vgpu,unsigned int offset,void * p_data,unsigned int bytes)378 int intel_gvt_i2c_handle_gmbus_read(struct intel_vgpu *vgpu,
379 	unsigned int offset, void *p_data, unsigned int bytes)
380 {
381 	struct drm_i915_private *i915 = vgpu->gvt->gt->i915;
382 
383 	if (drm_WARN_ON(&i915->drm, bytes > 8 && (offset & (bytes - 1))))
384 		return -EINVAL;
385 
386 	if (offset == i915_mmio_reg_offset(PCH_GMBUS2))
387 		return gmbus2_mmio_read(vgpu, offset, p_data, bytes);
388 	else if (offset == i915_mmio_reg_offset(PCH_GMBUS3))
389 		return gmbus3_mmio_read(vgpu, offset, p_data, bytes);
390 
391 	memcpy(p_data, &vgpu_vreg(vgpu, offset), bytes);
392 	return 0;
393 }
394 
395 /**
396  * intel_gvt_i2c_handle_gmbus_write - emulate gmbus register mmio write
397  * @vgpu: a vGPU
398  * @offset: reg offset
399  * @p_data: data return buffer
400  * @bytes: access data length
401  *
402  * This function is used to emulate gmbus register mmio write
403  *
404  * Returns:
405  * Zero on success, negative error code if failed.
406  *
407  */
intel_gvt_i2c_handle_gmbus_write(struct intel_vgpu * vgpu,unsigned int offset,void * p_data,unsigned int bytes)408 int intel_gvt_i2c_handle_gmbus_write(struct intel_vgpu *vgpu,
409 		unsigned int offset, void *p_data, unsigned int bytes)
410 {
411 	struct drm_i915_private *i915 = vgpu->gvt->gt->i915;
412 
413 	if (drm_WARN_ON(&i915->drm, bytes > 8 && (offset & (bytes - 1))))
414 		return -EINVAL;
415 
416 	if (offset == i915_mmio_reg_offset(PCH_GMBUS0))
417 		return gmbus0_mmio_write(vgpu, offset, p_data, bytes);
418 	else if (offset == i915_mmio_reg_offset(PCH_GMBUS1))
419 		return gmbus1_mmio_write(vgpu, offset, p_data, bytes);
420 	else if (offset == i915_mmio_reg_offset(PCH_GMBUS2))
421 		return gmbus2_mmio_write(vgpu, offset, p_data, bytes);
422 	else if (offset == i915_mmio_reg_offset(PCH_GMBUS3))
423 		return gmbus3_mmio_write(vgpu, offset, p_data, bytes);
424 
425 	memcpy(&vgpu_vreg(vgpu, offset), p_data, bytes);
426 	return 0;
427 }
428 
429 enum {
430 	AUX_CH_CTL = 0,
431 	AUX_CH_DATA1,
432 	AUX_CH_DATA2,
433 	AUX_CH_DATA3,
434 	AUX_CH_DATA4,
435 	AUX_CH_DATA5
436 };
437 
get_aux_ch_reg(unsigned int offset)438 static inline int get_aux_ch_reg(unsigned int offset)
439 {
440 	int reg;
441 
442 	switch (offset & 0xff) {
443 	case 0x10:
444 		reg = AUX_CH_CTL;
445 		break;
446 	case 0x14:
447 		reg = AUX_CH_DATA1;
448 		break;
449 	case 0x18:
450 		reg = AUX_CH_DATA2;
451 		break;
452 	case 0x1c:
453 		reg = AUX_CH_DATA3;
454 		break;
455 	case 0x20:
456 		reg = AUX_CH_DATA4;
457 		break;
458 	case 0x24:
459 		reg = AUX_CH_DATA5;
460 		break;
461 	default:
462 		reg = -1;
463 		break;
464 	}
465 	return reg;
466 }
467 
468 /**
469  * intel_gvt_i2c_handle_aux_ch_write - emulate AUX channel register write
470  * @vgpu: a vGPU
471  * @port_idx: port index
472  * @offset: reg offset
473  * @p_data: write ptr
474  *
475  * This function is used to emulate AUX channel register write
476  *
477  */
intel_gvt_i2c_handle_aux_ch_write(struct intel_vgpu * vgpu,int port_idx,unsigned int offset,void * p_data)478 void intel_gvt_i2c_handle_aux_ch_write(struct intel_vgpu *vgpu,
479 				int port_idx,
480 				unsigned int offset,
481 				void *p_data)
482 {
483 	struct drm_i915_private *i915 = vgpu->gvt->gt->i915;
484 	struct intel_vgpu_i2c_edid *i2c_edid = &vgpu->display.i2c_edid;
485 	int msg_length, ret_msg_size;
486 	int msg, addr, ctrl, op;
487 	u32 value = *(u32 *)p_data;
488 	int aux_data_for_write = 0;
489 	int reg = get_aux_ch_reg(offset);
490 
491 	if (reg != AUX_CH_CTL) {
492 		vgpu_vreg(vgpu, offset) = value;
493 		return;
494 	}
495 
496 	msg_length = REG_FIELD_GET(DP_AUX_CH_CTL_MESSAGE_SIZE_MASK, value);
497 
498 	// check the msg in DATA register.
499 	msg = vgpu_vreg(vgpu, offset + 4);
500 	addr = (msg >> 8) & 0xffff;
501 	ctrl = (msg >> 24) & 0xff;
502 	op = ctrl >> 4;
503 	if (!(value & DP_AUX_CH_CTL_SEND_BUSY)) {
504 		/* The ctl write to clear some states */
505 		return;
506 	}
507 
508 	/* Always set the wanted value for vms. */
509 	ret_msg_size = (((op & 0x1) == DP_AUX_I2C_READ) ? 2 : 1);
510 	vgpu_vreg(vgpu, offset) =
511 		DP_AUX_CH_CTL_DONE |
512 		DP_AUX_CH_CTL_MESSAGE_SIZE(ret_msg_size);
513 
514 	if (msg_length == 3) {
515 		if (!(op & DP_AUX_I2C_MOT)) {
516 			/* stop */
517 			intel_vgpu_init_i2c_edid(vgpu);
518 		} else {
519 			/* start or restart */
520 			i2c_edid->aux_ch.i2c_over_aux_ch = true;
521 			i2c_edid->aux_ch.aux_ch_mot = true;
522 			if (addr == 0) {
523 				/* reset the address */
524 				intel_vgpu_init_i2c_edid(vgpu);
525 			} else if (addr == EDID_ADDR) {
526 				i2c_edid->state = I2C_AUX_CH;
527 				i2c_edid->port = port_idx;
528 				i2c_edid->target_selected = true;
529 				if (intel_vgpu_has_monitor_on_port(vgpu,
530 					port_idx) &&
531 					intel_vgpu_port_is_dp(vgpu, port_idx))
532 					i2c_edid->edid_available = true;
533 			}
534 		}
535 	} else if ((op & 0x1) == DP_AUX_I2C_WRITE) {
536 		/* TODO
537 		 * We only support EDID reading from I2C_over_AUX. And
538 		 * we do not expect the index mode to be used. Right now
539 		 * the WRITE operation is ignored. It is good enough to
540 		 * support the gfx driver to do EDID access.
541 		 */
542 	} else {
543 		if (drm_WARN_ON(&i915->drm, (op & 0x1) != DP_AUX_I2C_READ))
544 			return;
545 		if (drm_WARN_ON(&i915->drm, msg_length != 4))
546 			return;
547 		if (i2c_edid->edid_available && i2c_edid->target_selected) {
548 			unsigned char val = edid_get_byte(vgpu);
549 
550 			aux_data_for_write = (val << 16);
551 		} else
552 			aux_data_for_write = (0xff << 16);
553 	}
554 	/* write the return value in AUX_CH_DATA reg which includes:
555 	 * ACK of I2C_WRITE
556 	 * returned byte if it is READ
557 	 */
558 	aux_data_for_write |= DP_AUX_I2C_REPLY_ACK << 24;
559 	vgpu_vreg(vgpu, offset + 4) = aux_data_for_write;
560 }
561 
562 /**
563  * intel_vgpu_init_i2c_edid - initialize vGPU i2c edid emulation
564  * @vgpu: a vGPU
565  *
566  * This function is used to initialize vGPU i2c edid emulation stuffs
567  *
568  */
intel_vgpu_init_i2c_edid(struct intel_vgpu * vgpu)569 void intel_vgpu_init_i2c_edid(struct intel_vgpu *vgpu)
570 {
571 	struct intel_vgpu_i2c_edid *edid = &vgpu->display.i2c_edid;
572 
573 	edid->state = I2C_NOT_SPECIFIED;
574 
575 	edid->port = -1;
576 	edid->target_selected = false;
577 	edid->edid_available = false;
578 	edid->current_edid_read = 0;
579 
580 	memset(&edid->gmbus, 0, sizeof(struct intel_vgpu_i2c_gmbus));
581 
582 	edid->aux_ch.i2c_over_aux_ch = false;
583 	edid->aux_ch.aux_ch_mot = false;
584 }
585