xref: /openbmc/linux/drivers/gpu/drm/i915/gvt/edid.c (revision 46d14e17)
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 "display/intel_dp_aux_regs.h"
36 #include "display/intel_gmbus_regs.h"
37 #include "gvt.h"
38 #include "i915_drv.h"
39 #include "i915_reg.h"
40 
41 #define GMBUS1_TOTAL_BYTES_SHIFT 16
42 #define GMBUS1_TOTAL_BYTES_MASK 0x1ff
43 #define gmbus1_total_byte_count(v) (((v) >> \
44 	GMBUS1_TOTAL_BYTES_SHIFT) & GMBUS1_TOTAL_BYTES_MASK)
45 #define gmbus1_slave_addr(v) (((v) & 0xff) >> 1)
46 #define gmbus1_slave_index(v) (((v) >> 8) & 0xff)
47 #define gmbus1_bus_cycle(v) (((v) >> 25) & 0x7)
48 
49 /* GMBUS0 bits definitions */
50 #define _GMBUS_PIN_SEL_MASK     (0x7)
51 
edid_get_byte(struct intel_vgpu * vgpu)52 static unsigned char edid_get_byte(struct intel_vgpu *vgpu)
53 {
54 	struct intel_vgpu_i2c_edid *edid = &vgpu->display.i2c_edid;
55 	unsigned char chr = 0;
56 
57 	if (edid->state == I2C_NOT_SPECIFIED || !edid->slave_selected) {
58 		gvt_vgpu_err("Driver tries to read EDID without proper sequence!\n");
59 		return 0;
60 	}
61 	if (edid->current_edid_read >= EDID_SIZE) {
62 		gvt_vgpu_err("edid_get_byte() exceeds the size of EDID!\n");
63 		return 0;
64 	}
65 
66 	if (!edid->edid_available) {
67 		gvt_vgpu_err("Reading EDID but EDID is not available!\n");
68 		return 0;
69 	}
70 
71 	if (intel_vgpu_has_monitor_on_port(vgpu, edid->port)) {
72 		struct intel_vgpu_edid_data *edid_data =
73 			intel_vgpu_port(vgpu, edid->port)->edid;
74 
75 		chr = edid_data->edid_block[edid->current_edid_read];
76 		edid->current_edid_read++;
77 	} else {
78 		gvt_vgpu_err("No EDID available during the reading?\n");
79 	}
80 	return chr;
81 }
82 
cnp_get_port_from_gmbus0(u32 gmbus0)83 static inline int cnp_get_port_from_gmbus0(u32 gmbus0)
84 {
85 	int port_select = gmbus0 & _GMBUS_PIN_SEL_MASK;
86 	int port = -EINVAL;
87 
88 	if (port_select == GMBUS_PIN_1_BXT)
89 		port = PORT_B;
90 	else if (port_select == GMBUS_PIN_2_BXT)
91 		port = PORT_C;
92 	else if (port_select == GMBUS_PIN_3_BXT)
93 		port = PORT_D;
94 	else if (port_select == GMBUS_PIN_4_CNP)
95 		port = PORT_E;
96 	return port;
97 }
98 
bxt_get_port_from_gmbus0(u32 gmbus0)99 static inline int bxt_get_port_from_gmbus0(u32 gmbus0)
100 {
101 	int port_select = gmbus0 & _GMBUS_PIN_SEL_MASK;
102 	int port = -EINVAL;
103 
104 	if (port_select == GMBUS_PIN_1_BXT)
105 		port = PORT_B;
106 	else if (port_select == GMBUS_PIN_2_BXT)
107 		port = PORT_C;
108 	else if (port_select == GMBUS_PIN_3_BXT)
109 		port = PORT_D;
110 	return port;
111 }
112 
get_port_from_gmbus0(u32 gmbus0)113 static inline int get_port_from_gmbus0(u32 gmbus0)
114 {
115 	int port_select = gmbus0 & _GMBUS_PIN_SEL_MASK;
116 	int port = -EINVAL;
117 
118 	if (port_select == GMBUS_PIN_VGADDC)
119 		port = PORT_E;
120 	else if (port_select == GMBUS_PIN_DPC)
121 		port = PORT_C;
122 	else if (port_select == GMBUS_PIN_DPB)
123 		port = PORT_B;
124 	else if (port_select == GMBUS_PIN_DPD)
125 		port = PORT_D;
126 	return port;
127 }
128 
reset_gmbus_controller(struct intel_vgpu * vgpu)129 static void reset_gmbus_controller(struct intel_vgpu *vgpu)
130 {
131 	vgpu_vreg_t(vgpu, PCH_GMBUS2) = GMBUS_HW_RDY;
132 	if (!vgpu->display.i2c_edid.edid_available)
133 		vgpu_vreg_t(vgpu, PCH_GMBUS2) |= GMBUS_SATOER;
134 	vgpu->display.i2c_edid.gmbus.phase = GMBUS_IDLE_PHASE;
135 }
136 
137 /* GMBUS0 */
gmbus0_mmio_write(struct intel_vgpu * vgpu,unsigned int offset,void * p_data,unsigned int bytes)138 static int gmbus0_mmio_write(struct intel_vgpu *vgpu,
139 			unsigned int offset, void *p_data, unsigned int bytes)
140 {
141 	struct drm_i915_private *i915 = vgpu->gvt->gt->i915;
142 	int port, pin_select;
143 
144 	memcpy(&vgpu_vreg(vgpu, offset), p_data, bytes);
145 
146 	pin_select = vgpu_vreg(vgpu, offset) & _GMBUS_PIN_SEL_MASK;
147 
148 	intel_vgpu_init_i2c_edid(vgpu);
149 
150 	if (pin_select == 0)
151 		return 0;
152 
153 	if (IS_BROXTON(i915))
154 		port = bxt_get_port_from_gmbus0(pin_select);
155 	else if (IS_COFFEELAKE(i915) || IS_COMETLAKE(i915))
156 		port = cnp_get_port_from_gmbus0(pin_select);
157 	else
158 		port = get_port_from_gmbus0(pin_select);
159 	if (drm_WARN_ON(&i915->drm, port < 0))
160 		return 0;
161 
162 	vgpu->display.i2c_edid.state = I2C_GMBUS;
163 	vgpu->display.i2c_edid.gmbus.phase = GMBUS_IDLE_PHASE;
164 
165 	vgpu_vreg_t(vgpu, PCH_GMBUS2) &= ~GMBUS_ACTIVE;
166 	vgpu_vreg_t(vgpu, PCH_GMBUS2) |= GMBUS_HW_RDY | GMBUS_HW_WAIT_PHASE;
167 
168 	if (intel_vgpu_has_monitor_on_port(vgpu, port) &&
169 			!intel_vgpu_port_is_dp(vgpu, port)) {
170 		vgpu->display.i2c_edid.port = port;
171 		vgpu->display.i2c_edid.edid_available = true;
172 		vgpu_vreg_t(vgpu, PCH_GMBUS2) &= ~GMBUS_SATOER;
173 	} else
174 		vgpu_vreg_t(vgpu, PCH_GMBUS2) |= GMBUS_SATOER;
175 	return 0;
176 }
177 
gmbus1_mmio_write(struct intel_vgpu * vgpu,unsigned int offset,void * p_data,unsigned int bytes)178 static int gmbus1_mmio_write(struct intel_vgpu *vgpu, unsigned int offset,
179 		void *p_data, unsigned int bytes)
180 {
181 	struct intel_vgpu_i2c_edid *i2c_edid = &vgpu->display.i2c_edid;
182 	u32 slave_addr;
183 	u32 wvalue = *(u32 *)p_data;
184 
185 	if (vgpu_vreg(vgpu, offset) & GMBUS_SW_CLR_INT) {
186 		if (!(wvalue & GMBUS_SW_CLR_INT)) {
187 			vgpu_vreg(vgpu, offset) &= ~GMBUS_SW_CLR_INT;
188 			reset_gmbus_controller(vgpu);
189 		}
190 		/*
191 		 * TODO: "This bit is cleared to zero when an event
192 		 * causes the HW_RDY bit transition to occur "
193 		 */
194 	} else {
195 		/*
196 		 * per bspec setting this bit can cause:
197 		 * 1) INT status bit cleared
198 		 * 2) HW_RDY bit asserted
199 		 */
200 		if (wvalue & GMBUS_SW_CLR_INT) {
201 			vgpu_vreg_t(vgpu, PCH_GMBUS2) &= ~GMBUS_INT;
202 			vgpu_vreg_t(vgpu, PCH_GMBUS2) |= GMBUS_HW_RDY;
203 		}
204 
205 		/* For virtualization, we suppose that HW is always ready,
206 		 * so GMBUS_SW_RDY should always be cleared
207 		 */
208 		if (wvalue & GMBUS_SW_RDY)
209 			wvalue &= ~GMBUS_SW_RDY;
210 
211 		i2c_edid->gmbus.total_byte_count =
212 			gmbus1_total_byte_count(wvalue);
213 		slave_addr = gmbus1_slave_addr(wvalue);
214 
215 		/* vgpu gmbus only support EDID */
216 		if (slave_addr == EDID_ADDR) {
217 			i2c_edid->slave_selected = true;
218 		} else if (slave_addr != 0) {
219 			gvt_dbg_dpy(
220 				"vgpu%d: unsupported gmbus slave addr(0x%x)\n"
221 				"	gmbus operations will be ignored.\n",
222 					vgpu->id, slave_addr);
223 		}
224 
225 		if (wvalue & GMBUS_CYCLE_INDEX)
226 			i2c_edid->current_edid_read =
227 				gmbus1_slave_index(wvalue);
228 
229 		i2c_edid->gmbus.cycle_type = gmbus1_bus_cycle(wvalue);
230 		switch (gmbus1_bus_cycle(wvalue)) {
231 		case GMBUS_NOCYCLE:
232 			break;
233 		case GMBUS_STOP:
234 			/* From spec:
235 			 * This can only cause a STOP to be generated
236 			 * if a GMBUS cycle is generated, the GMBUS is
237 			 * currently in a data/wait/idle phase, or it is in a
238 			 * WAIT phase
239 			 */
240 			if (gmbus1_bus_cycle(vgpu_vreg(vgpu, offset))
241 				!= GMBUS_NOCYCLE) {
242 				intel_vgpu_init_i2c_edid(vgpu);
243 				/* After the 'stop' cycle, hw state would become
244 				 * 'stop phase' and then 'idle phase' after a
245 				 * few milliseconds. In emulation, we just set
246 				 * it as 'idle phase' ('stop phase' is not
247 				 * visible in gmbus interface)
248 				 */
249 				i2c_edid->gmbus.phase = GMBUS_IDLE_PHASE;
250 				vgpu_vreg_t(vgpu, PCH_GMBUS2) &= ~GMBUS_ACTIVE;
251 			}
252 			break;
253 		case NIDX_NS_W:
254 		case IDX_NS_W:
255 		case NIDX_STOP:
256 		case IDX_STOP:
257 			/* From hw spec the GMBUS phase
258 			 * transition like this:
259 			 * START (-->INDEX) -->DATA
260 			 */
261 			i2c_edid->gmbus.phase = GMBUS_DATA_PHASE;
262 			vgpu_vreg_t(vgpu, PCH_GMBUS2) |= GMBUS_ACTIVE;
263 			break;
264 		default:
265 			gvt_vgpu_err("Unknown/reserved GMBUS cycle detected!\n");
266 			break;
267 		}
268 		/*
269 		 * From hw spec the WAIT state will be
270 		 * cleared:
271 		 * (1) in a new GMBUS cycle
272 		 * (2) by generating a stop
273 		 */
274 		vgpu_vreg(vgpu, offset) = wvalue;
275 	}
276 	return 0;
277 }
278 
gmbus3_mmio_write(struct intel_vgpu * vgpu,unsigned int offset,void * p_data,unsigned int bytes)279 static int gmbus3_mmio_write(struct intel_vgpu *vgpu, unsigned int offset,
280 	void *p_data, unsigned int bytes)
281 {
282 	struct drm_i915_private *i915 = vgpu->gvt->gt->i915;
283 
284 	drm_WARN_ON(&i915->drm, 1);
285 	return 0;
286 }
287 
gmbus3_mmio_read(struct intel_vgpu * vgpu,unsigned int offset,void * p_data,unsigned int bytes)288 static int gmbus3_mmio_read(struct intel_vgpu *vgpu, unsigned int offset,
289 		void *p_data, unsigned int bytes)
290 {
291 	int i;
292 	unsigned char byte_data;
293 	struct intel_vgpu_i2c_edid *i2c_edid = &vgpu->display.i2c_edid;
294 	int byte_left = i2c_edid->gmbus.total_byte_count -
295 				i2c_edid->current_edid_read;
296 	int byte_count = byte_left;
297 	u32 reg_data = 0;
298 
299 	/* Data can only be recevied if previous settings correct */
300 	if (vgpu_vreg_t(vgpu, PCH_GMBUS1) & GMBUS_SLAVE_READ) {
301 		if (byte_left <= 0) {
302 			memcpy(p_data, &vgpu_vreg(vgpu, offset), bytes);
303 			return 0;
304 		}
305 
306 		if (byte_count > 4)
307 			byte_count = 4;
308 		for (i = 0; i < byte_count; i++) {
309 			byte_data = edid_get_byte(vgpu);
310 			reg_data |= (byte_data << (i << 3));
311 		}
312 
313 		memcpy(&vgpu_vreg(vgpu, offset), &reg_data, byte_count);
314 		memcpy(p_data, &vgpu_vreg(vgpu, offset), bytes);
315 
316 		if (byte_left <= 4) {
317 			switch (i2c_edid->gmbus.cycle_type) {
318 			case NIDX_STOP:
319 			case IDX_STOP:
320 				i2c_edid->gmbus.phase = GMBUS_IDLE_PHASE;
321 				break;
322 			case NIDX_NS_W:
323 			case IDX_NS_W:
324 			default:
325 				i2c_edid->gmbus.phase = GMBUS_WAIT_PHASE;
326 				break;
327 			}
328 			intel_vgpu_init_i2c_edid(vgpu);
329 		}
330 		/*
331 		 * Read GMBUS3 during send operation,
332 		 * return the latest written value
333 		 */
334 	} else {
335 		memcpy(p_data, &vgpu_vreg(vgpu, offset), bytes);
336 		gvt_vgpu_err("warning: gmbus3 read with nothing returned\n");
337 	}
338 	return 0;
339 }
340 
gmbus2_mmio_read(struct intel_vgpu * vgpu,unsigned int offset,void * p_data,unsigned int bytes)341 static int gmbus2_mmio_read(struct intel_vgpu *vgpu, unsigned int offset,
342 		void *p_data, unsigned int bytes)
343 {
344 	u32 value = vgpu_vreg(vgpu, offset);
345 
346 	if (!(vgpu_vreg(vgpu, offset) & GMBUS_INUSE))
347 		vgpu_vreg(vgpu, offset) |= GMBUS_INUSE;
348 	memcpy(p_data, (void *)&value, bytes);
349 	return 0;
350 }
351 
gmbus2_mmio_write(struct intel_vgpu * vgpu,unsigned int offset,void * p_data,unsigned int bytes)352 static int gmbus2_mmio_write(struct intel_vgpu *vgpu, unsigned int offset,
353 		void *p_data, unsigned int bytes)
354 {
355 	u32 wvalue = *(u32 *)p_data;
356 
357 	if (wvalue & GMBUS_INUSE)
358 		vgpu_vreg(vgpu, offset) &= ~GMBUS_INUSE;
359 	/* All other bits are read-only */
360 	return 0;
361 }
362 
363 /**
364  * intel_gvt_i2c_handle_gmbus_read - emulate gmbus register mmio read
365  * @vgpu: a vGPU
366  * @offset: reg offset
367  * @p_data: data return buffer
368  * @bytes: access data length
369  *
370  * This function is used to emulate gmbus register mmio read
371  *
372  * Returns:
373  * Zero on success, negative error code if failed.
374  *
375  */
intel_gvt_i2c_handle_gmbus_read(struct intel_vgpu * vgpu,unsigned int offset,void * p_data,unsigned int bytes)376 int intel_gvt_i2c_handle_gmbus_read(struct intel_vgpu *vgpu,
377 	unsigned int offset, void *p_data, unsigned int bytes)
378 {
379 	struct drm_i915_private *i915 = vgpu->gvt->gt->i915;
380 
381 	if (drm_WARN_ON(&i915->drm, bytes > 8 && (offset & (bytes - 1))))
382 		return -EINVAL;
383 
384 	if (offset == i915_mmio_reg_offset(PCH_GMBUS2))
385 		return gmbus2_mmio_read(vgpu, offset, p_data, bytes);
386 	else if (offset == i915_mmio_reg_offset(PCH_GMBUS3))
387 		return gmbus3_mmio_read(vgpu, offset, p_data, bytes);
388 
389 	memcpy(p_data, &vgpu_vreg(vgpu, offset), bytes);
390 	return 0;
391 }
392 
393 /**
394  * intel_gvt_i2c_handle_gmbus_write - emulate gmbus register mmio write
395  * @vgpu: a vGPU
396  * @offset: reg offset
397  * @p_data: data return buffer
398  * @bytes: access data length
399  *
400  * This function is used to emulate gmbus register mmio write
401  *
402  * Returns:
403  * Zero on success, negative error code if failed.
404  *
405  */
intel_gvt_i2c_handle_gmbus_write(struct intel_vgpu * vgpu,unsigned int offset,void * p_data,unsigned int bytes)406 int intel_gvt_i2c_handle_gmbus_write(struct intel_vgpu *vgpu,
407 		unsigned int offset, void *p_data, unsigned int bytes)
408 {
409 	struct drm_i915_private *i915 = vgpu->gvt->gt->i915;
410 
411 	if (drm_WARN_ON(&i915->drm, bytes > 8 && (offset & (bytes - 1))))
412 		return -EINVAL;
413 
414 	if (offset == i915_mmio_reg_offset(PCH_GMBUS0))
415 		return gmbus0_mmio_write(vgpu, offset, p_data, bytes);
416 	else if (offset == i915_mmio_reg_offset(PCH_GMBUS1))
417 		return gmbus1_mmio_write(vgpu, offset, p_data, bytes);
418 	else if (offset == i915_mmio_reg_offset(PCH_GMBUS2))
419 		return gmbus2_mmio_write(vgpu, offset, p_data, bytes);
420 	else if (offset == i915_mmio_reg_offset(PCH_GMBUS3))
421 		return gmbus3_mmio_write(vgpu, offset, p_data, bytes);
422 
423 	memcpy(&vgpu_vreg(vgpu, offset), p_data, bytes);
424 	return 0;
425 }
426 
427 enum {
428 	AUX_CH_CTL = 0,
429 	AUX_CH_DATA1,
430 	AUX_CH_DATA2,
431 	AUX_CH_DATA3,
432 	AUX_CH_DATA4,
433 	AUX_CH_DATA5
434 };
435 
get_aux_ch_reg(unsigned int offset)436 static inline int get_aux_ch_reg(unsigned int offset)
437 {
438 	int reg;
439 
440 	switch (offset & 0xff) {
441 	case 0x10:
442 		reg = AUX_CH_CTL;
443 		break;
444 	case 0x14:
445 		reg = AUX_CH_DATA1;
446 		break;
447 	case 0x18:
448 		reg = AUX_CH_DATA2;
449 		break;
450 	case 0x1c:
451 		reg = AUX_CH_DATA3;
452 		break;
453 	case 0x20:
454 		reg = AUX_CH_DATA4;
455 		break;
456 	case 0x24:
457 		reg = AUX_CH_DATA5;
458 		break;
459 	default:
460 		reg = -1;
461 		break;
462 	}
463 	return reg;
464 }
465 
466 /**
467  * intel_gvt_i2c_handle_aux_ch_write - emulate AUX channel register write
468  * @vgpu: a vGPU
469  * @port_idx: port index
470  * @offset: reg offset
471  * @p_data: write ptr
472  *
473  * This function is used to emulate AUX channel register write
474  *
475  */
intel_gvt_i2c_handle_aux_ch_write(struct intel_vgpu * vgpu,int port_idx,unsigned int offset,void * p_data)476 void intel_gvt_i2c_handle_aux_ch_write(struct intel_vgpu *vgpu,
477 				int port_idx,
478 				unsigned int offset,
479 				void *p_data)
480 {
481 	struct drm_i915_private *i915 = vgpu->gvt->gt->i915;
482 	struct intel_vgpu_i2c_edid *i2c_edid = &vgpu->display.i2c_edid;
483 	int msg_length, ret_msg_size;
484 	int msg, addr, ctrl, op;
485 	u32 value = *(u32 *)p_data;
486 	int aux_data_for_write = 0;
487 	int reg = get_aux_ch_reg(offset);
488 
489 	if (reg != AUX_CH_CTL) {
490 		vgpu_vreg(vgpu, offset) = value;
491 		return;
492 	}
493 
494 	msg_length = REG_FIELD_GET(DP_AUX_CH_CTL_MESSAGE_SIZE_MASK, value);
495 
496 	// check the msg in DATA register.
497 	msg = vgpu_vreg(vgpu, offset + 4);
498 	addr = (msg >> 8) & 0xffff;
499 	ctrl = (msg >> 24) & 0xff;
500 	op = ctrl >> 4;
501 	if (!(value & DP_AUX_CH_CTL_SEND_BUSY)) {
502 		/* The ctl write to clear some states */
503 		return;
504 	}
505 
506 	/* Always set the wanted value for vms. */
507 	ret_msg_size = (((op & 0x1) == GVT_AUX_I2C_READ) ? 2 : 1);
508 	vgpu_vreg(vgpu, offset) =
509 		DP_AUX_CH_CTL_DONE |
510 		DP_AUX_CH_CTL_MESSAGE_SIZE(ret_msg_size);
511 
512 	if (msg_length == 3) {
513 		if (!(op & GVT_AUX_I2C_MOT)) {
514 			/* stop */
515 			intel_vgpu_init_i2c_edid(vgpu);
516 		} else {
517 			/* start or restart */
518 			i2c_edid->aux_ch.i2c_over_aux_ch = true;
519 			i2c_edid->aux_ch.aux_ch_mot = true;
520 			if (addr == 0) {
521 				/* reset the address */
522 				intel_vgpu_init_i2c_edid(vgpu);
523 			} else if (addr == EDID_ADDR) {
524 				i2c_edid->state = I2C_AUX_CH;
525 				i2c_edid->port = port_idx;
526 				i2c_edid->slave_selected = true;
527 				if (intel_vgpu_has_monitor_on_port(vgpu,
528 					port_idx) &&
529 					intel_vgpu_port_is_dp(vgpu, port_idx))
530 					i2c_edid->edid_available = true;
531 			}
532 		}
533 	} else if ((op & 0x1) == GVT_AUX_I2C_WRITE) {
534 		/* TODO
535 		 * We only support EDID reading from I2C_over_AUX. And
536 		 * we do not expect the index mode to be used. Right now
537 		 * the WRITE operation is ignored. It is good enough to
538 		 * support the gfx driver to do EDID access.
539 		 */
540 	} else {
541 		if (drm_WARN_ON(&i915->drm, (op & 0x1) != GVT_AUX_I2C_READ))
542 			return;
543 		if (drm_WARN_ON(&i915->drm, msg_length != 4))
544 			return;
545 		if (i2c_edid->edid_available && i2c_edid->slave_selected) {
546 			unsigned char val = edid_get_byte(vgpu);
547 
548 			aux_data_for_write = (val << 16);
549 		} else
550 			aux_data_for_write = (0xff << 16);
551 	}
552 	/* write the return value in AUX_CH_DATA reg which includes:
553 	 * ACK of I2C_WRITE
554 	 * returned byte if it is READ
555 	 */
556 	aux_data_for_write |= GVT_AUX_I2C_REPLY_ACK << 24;
557 	vgpu_vreg(vgpu, offset + 4) = aux_data_for_write;
558 }
559 
560 /**
561  * intel_vgpu_init_i2c_edid - initialize vGPU i2c edid emulation
562  * @vgpu: a vGPU
563  *
564  * This function is used to initialize vGPU i2c edid emulation stuffs
565  *
566  */
intel_vgpu_init_i2c_edid(struct intel_vgpu * vgpu)567 void intel_vgpu_init_i2c_edid(struct intel_vgpu *vgpu)
568 {
569 	struct intel_vgpu_i2c_edid *edid = &vgpu->display.i2c_edid;
570 
571 	edid->state = I2C_NOT_SPECIFIED;
572 
573 	edid->port = -1;
574 	edid->slave_selected = false;
575 	edid->edid_available = false;
576 	edid->current_edid_read = 0;
577 
578 	memset(&edid->gmbus, 0, sizeof(struct intel_vgpu_i2c_gmbus));
579 
580 	edid->aux_ch.i2c_over_aux_ch = false;
581 	edid->aux_ch.aux_ch_mot = false;
582 }
583