1 /*
2  * Copyright 2019 Advanced Micro Devices, Inc.
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 shall be included in
12  * all copies or substantial portions of the Software.
13  *
14  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
15  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
16  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
17  * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR
18  * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
19  * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
20  * OTHER DEALINGS IN THE SOFTWARE.
21  *
22  */
23 
24 #include "amdgpu_ras_eeprom.h"
25 #include "amdgpu.h"
26 #include "amdgpu_ras.h"
27 #include <linux/bits.h>
28 #include "atom.h"
29 
30 #define EEPROM_I2C_TARGET_ADDR_VEGA20		0xA0
31 #define EEPROM_I2C_TARGET_ADDR_ARCTURUS		0xA8
32 #define EEPROM_I2C_TARGET_ADDR_ARCTURUS_D342	0xA0
33 #define EEPROM_I2C_TARGET_ADDR_SIENNA_CICHLID   0xA0
34 
35 /*
36  * The 2 macros bellow represent the actual size in bytes that
37  * those entities occupy in the EEPROM memory.
38  * EEPROM_TABLE_RECORD_SIZE is different than sizeof(eeprom_table_record) which
39  * uses uint64 to store 6b fields such as retired_page.
40  */
41 #define EEPROM_TABLE_HEADER_SIZE 20
42 #define EEPROM_TABLE_RECORD_SIZE 24
43 
44 #define EEPROM_ADDRESS_SIZE 0x2
45 
46 /* Table hdr is 'AMDR' */
47 #define EEPROM_TABLE_HDR_VAL 0x414d4452
48 #define EEPROM_TABLE_VER 0x00010000
49 
50 /* Bad GPU tag ‘BADG’ */
51 #define EEPROM_TABLE_HDR_BAD 0x42414447
52 
53 /* Assume 2 Mbit size */
54 #define EEPROM_SIZE_BYTES 256000
55 #define EEPROM_PAGE__SIZE_BYTES 256
56 #define EEPROM_HDR_START 0
57 #define EEPROM_RECORD_START (EEPROM_HDR_START + EEPROM_TABLE_HEADER_SIZE)
58 #define EEPROM_MAX_RECORD_NUM ((EEPROM_SIZE_BYTES - EEPROM_TABLE_HEADER_SIZE) / EEPROM_TABLE_RECORD_SIZE)
59 #define EEPROM_ADDR_MSB_MASK GENMASK(17, 8)
60 
61 #define to_amdgpu_device(x) (container_of(x, struct amdgpu_ras, eeprom_control))->adev
62 
63 static bool __is_ras_eeprom_supported(struct amdgpu_device *adev)
64 {
65 	if ((adev->asic_type == CHIP_VEGA20) ||
66 	    (adev->asic_type == CHIP_ARCTURUS) ||
67 	    (adev->asic_type == CHIP_SIENNA_CICHLID))
68 		return true;
69 
70 	return false;
71 }
72 
73 static bool __get_eeprom_i2c_addr_arct(struct amdgpu_device *adev,
74 				       uint16_t *i2c_addr)
75 {
76 	struct atom_context *atom_ctx = adev->mode_info.atom_context;
77 
78 	if (!i2c_addr || !atom_ctx)
79 		return false;
80 
81 	if (strnstr(atom_ctx->vbios_version,
82 	            "D342",
83 		    sizeof(atom_ctx->vbios_version)))
84 		*i2c_addr = EEPROM_I2C_TARGET_ADDR_ARCTURUS_D342;
85 	else
86 		*i2c_addr = EEPROM_I2C_TARGET_ADDR_ARCTURUS;
87 
88 	return true;
89 }
90 
91 static bool __get_eeprom_i2c_addr(struct amdgpu_device *adev,
92 				  uint16_t *i2c_addr)
93 {
94 	if (!i2c_addr)
95 		return false;
96 
97 	switch (adev->asic_type) {
98 	case CHIP_VEGA20:
99 		*i2c_addr = EEPROM_I2C_TARGET_ADDR_VEGA20;
100 		break;
101 
102 	case CHIP_ARCTURUS:
103 		return __get_eeprom_i2c_addr_arct(adev, i2c_addr);
104 
105 	case CHIP_SIENNA_CICHLID:
106 		*i2c_addr = EEPROM_I2C_TARGET_ADDR_SIENNA_CICHLID;
107 		break;
108 
109 	default:
110 		return false;
111 	}
112 
113 	return true;
114 }
115 
116 static void __encode_table_header_to_buff(struct amdgpu_ras_eeprom_table_header *hdr,
117 					  unsigned char *buff)
118 {
119 	uint32_t *pp = (uint32_t *) buff;
120 
121 	pp[0] = cpu_to_le32(hdr->header);
122 	pp[1] = cpu_to_le32(hdr->version);
123 	pp[2] = cpu_to_le32(hdr->first_rec_offset);
124 	pp[3] = cpu_to_le32(hdr->tbl_size);
125 	pp[4] = cpu_to_le32(hdr->checksum);
126 }
127 
128 static void __decode_table_header_from_buff(struct amdgpu_ras_eeprom_table_header *hdr,
129 					  unsigned char *buff)
130 {
131 	uint32_t *pp = (uint32_t *)buff;
132 
133 	hdr->header	      = le32_to_cpu(pp[0]);
134 	hdr->version	      = le32_to_cpu(pp[1]);
135 	hdr->first_rec_offset = le32_to_cpu(pp[2]);
136 	hdr->tbl_size	      = le32_to_cpu(pp[3]);
137 	hdr->checksum	      = le32_to_cpu(pp[4]);
138 }
139 
140 static int __update_table_header(struct amdgpu_ras_eeprom_control *control,
141 				 unsigned char *buff)
142 {
143 	int ret = 0;
144 	struct amdgpu_device *adev = to_amdgpu_device(control);
145 	struct i2c_msg msg = {
146 			.addr	= 0,
147 			.flags	= 0,
148 			.len	= EEPROM_ADDRESS_SIZE + EEPROM_TABLE_HEADER_SIZE,
149 			.buf	= buff,
150 	};
151 
152 
153 	*(uint16_t *)buff = EEPROM_HDR_START;
154 	__encode_table_header_to_buff(&control->tbl_hdr, buff + EEPROM_ADDRESS_SIZE);
155 
156 	msg.addr = control->i2c_address;
157 
158 	/* i2c may be unstable in gpu reset */
159 	down_read(&adev->reset_sem);
160 	ret = i2c_transfer(&adev->pm.smu_i2c, &msg, 1);
161 	up_read(&adev->reset_sem);
162 
163 	if (ret < 1)
164 		DRM_ERROR("Failed to write EEPROM table header, ret:%d", ret);
165 
166 	return ret;
167 }
168 
169 static uint32_t  __calc_hdr_byte_sum(struct amdgpu_ras_eeprom_control *control)
170 {
171 	int i;
172 	uint32_t tbl_sum = 0;
173 
174 	/* Header checksum, skip checksum field in the calculation */
175 	for (i = 0; i < sizeof(control->tbl_hdr) - sizeof(control->tbl_hdr.checksum); i++)
176 		tbl_sum += *(((unsigned char *)&control->tbl_hdr) + i);
177 
178 	return tbl_sum;
179 }
180 
181 static uint32_t  __calc_recs_byte_sum(struct eeprom_table_record *records,
182 				      int num)
183 {
184 	int i, j;
185 	uint32_t tbl_sum = 0;
186 
187 	/* Records checksum */
188 	for (i = 0; i < num; i++) {
189 		struct eeprom_table_record *record = &records[i];
190 
191 		for (j = 0; j < sizeof(*record); j++) {
192 			tbl_sum += *(((unsigned char *)record) + j);
193 		}
194 	}
195 
196 	return tbl_sum;
197 }
198 
199 static inline uint32_t  __calc_tbl_byte_sum(struct amdgpu_ras_eeprom_control *control,
200 				  struct eeprom_table_record *records, int num)
201 {
202 	return __calc_hdr_byte_sum(control) + __calc_recs_byte_sum(records, num);
203 }
204 
205 /* Checksum = 256 -((sum of all table entries) mod 256) */
206 static void __update_tbl_checksum(struct amdgpu_ras_eeprom_control *control,
207 				  struct eeprom_table_record *records, int num,
208 				  uint32_t old_hdr_byte_sum)
209 {
210 	/*
211 	 * This will update the table sum with new records.
212 	 *
213 	 * TODO: What happens when the EEPROM table is to be wrapped around
214 	 * and old records from start will get overridden.
215 	 */
216 
217 	/* need to recalculate updated header byte sum */
218 	control->tbl_byte_sum -= old_hdr_byte_sum;
219 	control->tbl_byte_sum += __calc_tbl_byte_sum(control, records, num);
220 
221 	control->tbl_hdr.checksum = 256 - (control->tbl_byte_sum % 256);
222 }
223 
224 /* table sum mod 256 + checksum must equals 256 */
225 static bool __validate_tbl_checksum(struct amdgpu_ras_eeprom_control *control,
226 			    struct eeprom_table_record *records, int num)
227 {
228 	control->tbl_byte_sum = __calc_tbl_byte_sum(control, records, num);
229 
230 	if (control->tbl_hdr.checksum + (control->tbl_byte_sum % 256) != 256) {
231 		DRM_WARN("Checksum mismatch, checksum: %u ", control->tbl_hdr.checksum);
232 		return false;
233 	}
234 
235 	return true;
236 }
237 
238 static int amdgpu_ras_eeprom_correct_header_tag(
239 				struct amdgpu_ras_eeprom_control *control,
240 				uint32_t header)
241 {
242 	unsigned char buff[EEPROM_ADDRESS_SIZE + EEPROM_TABLE_HEADER_SIZE];
243 	struct amdgpu_ras_eeprom_table_header *hdr = &control->tbl_hdr;
244 	int ret = 0;
245 
246 	memset(buff, 0, EEPROM_ADDRESS_SIZE + EEPROM_TABLE_HEADER_SIZE);
247 
248 	mutex_lock(&control->tbl_mutex);
249 	hdr->header = header;
250 	ret = __update_table_header(control, buff);
251 	mutex_unlock(&control->tbl_mutex);
252 
253 	return ret;
254 }
255 
256 int amdgpu_ras_eeprom_reset_table(struct amdgpu_ras_eeprom_control *control)
257 {
258 	unsigned char buff[EEPROM_ADDRESS_SIZE + EEPROM_TABLE_HEADER_SIZE] = { 0 };
259 	struct amdgpu_ras_eeprom_table_header *hdr = &control->tbl_hdr;
260 	int ret = 0;
261 
262 	mutex_lock(&control->tbl_mutex);
263 
264 	hdr->header = EEPROM_TABLE_HDR_VAL;
265 	hdr->version = EEPROM_TABLE_VER;
266 	hdr->first_rec_offset = EEPROM_RECORD_START;
267 	hdr->tbl_size = EEPROM_TABLE_HEADER_SIZE;
268 
269 	control->tbl_byte_sum = 0;
270 	__update_tbl_checksum(control, NULL, 0, 0);
271 	control->next_addr = EEPROM_RECORD_START;
272 
273 	ret = __update_table_header(control, buff);
274 
275 	mutex_unlock(&control->tbl_mutex);
276 
277 	return ret;
278 
279 }
280 
281 int amdgpu_ras_eeprom_init(struct amdgpu_ras_eeprom_control *control,
282 			bool *exceed_err_limit)
283 {
284 	int ret = 0;
285 	struct amdgpu_device *adev = to_amdgpu_device(control);
286 	unsigned char buff[EEPROM_ADDRESS_SIZE + EEPROM_TABLE_HEADER_SIZE] = { 0 };
287 	struct amdgpu_ras_eeprom_table_header *hdr = &control->tbl_hdr;
288 	struct amdgpu_ras *ras = amdgpu_ras_get_context(adev);
289 	struct i2c_msg msg = {
290 			.addr	= 0,
291 			.flags	= I2C_M_RD,
292 			.len	= EEPROM_ADDRESS_SIZE + EEPROM_TABLE_HEADER_SIZE,
293 			.buf	= buff,
294 	};
295 
296 	*exceed_err_limit = false;
297 
298 	if (!__is_ras_eeprom_supported(adev))
299 		return 0;
300 
301 	/* Verify i2c adapter is initialized */
302 	if (!adev->pm.smu_i2c.algo)
303 		return -ENOENT;
304 
305 	if (!__get_eeprom_i2c_addr(adev, &control->i2c_address))
306 		return -EINVAL;
307 
308 	mutex_init(&control->tbl_mutex);
309 
310 	msg.addr = control->i2c_address;
311 	/* Read/Create table header from EEPROM address 0 */
312 	ret = i2c_transfer(&adev->pm.smu_i2c, &msg, 1);
313 	if (ret < 1) {
314 		DRM_ERROR("Failed to read EEPROM table header, ret:%d", ret);
315 		return ret;
316 	}
317 
318 	__decode_table_header_from_buff(hdr, &buff[2]);
319 
320 	if (hdr->header == EEPROM_TABLE_HDR_VAL) {
321 		control->num_recs = (hdr->tbl_size - EEPROM_TABLE_HEADER_SIZE) /
322 				    EEPROM_TABLE_RECORD_SIZE;
323 		control->tbl_byte_sum = __calc_hdr_byte_sum(control);
324 		control->next_addr = EEPROM_RECORD_START;
325 
326 		DRM_DEBUG_DRIVER("Found existing EEPROM table with %d records",
327 				 control->num_recs);
328 
329 	} else if ((hdr->header == EEPROM_TABLE_HDR_BAD) &&
330 			(amdgpu_bad_page_threshold != 0)) {
331 		if (ras->bad_page_cnt_threshold > control->num_recs) {
332 			dev_info(adev->dev, "Using one valid bigger bad page "
333 				"threshold and correcting eeprom header tag.\n");
334 			ret = amdgpu_ras_eeprom_correct_header_tag(control,
335 							EEPROM_TABLE_HDR_VAL);
336 		} else {
337 			*exceed_err_limit = true;
338 			dev_err(adev->dev, "Exceeding the bad_page_threshold parameter, "
339 				"disabling the GPU.\n");
340 		}
341 	} else {
342 		DRM_INFO("Creating new EEPROM table");
343 
344 		ret = amdgpu_ras_eeprom_reset_table(control);
345 	}
346 
347 	return ret == 1 ? 0 : -EIO;
348 }
349 
350 static void __encode_table_record_to_buff(struct amdgpu_ras_eeprom_control *control,
351 					  struct eeprom_table_record *record,
352 					  unsigned char *buff)
353 {
354 	__le64 tmp = 0;
355 	int i = 0;
356 
357 	/* Next are all record fields according to EEPROM page spec in LE foramt */
358 	buff[i++] = record->err_type;
359 
360 	buff[i++] = record->bank;
361 
362 	tmp = cpu_to_le64(record->ts);
363 	memcpy(buff + i, &tmp, 8);
364 	i += 8;
365 
366 	tmp = cpu_to_le64((record->offset & 0xffffffffffff));
367 	memcpy(buff + i, &tmp, 6);
368 	i += 6;
369 
370 	buff[i++] = record->mem_channel;
371 	buff[i++] = record->mcumc_id;
372 
373 	tmp = cpu_to_le64((record->retired_page & 0xffffffffffff));
374 	memcpy(buff + i, &tmp, 6);
375 }
376 
377 static void __decode_table_record_from_buff(struct amdgpu_ras_eeprom_control *control,
378 					    struct eeprom_table_record *record,
379 					    unsigned char *buff)
380 {
381 	__le64 tmp = 0;
382 	int i =  0;
383 
384 	/* Next are all record fields according to EEPROM page spec in LE foramt */
385 	record->err_type = buff[i++];
386 
387 	record->bank = buff[i++];
388 
389 	memcpy(&tmp, buff + i, 8);
390 	record->ts = le64_to_cpu(tmp);
391 	i += 8;
392 
393 	memcpy(&tmp, buff + i, 6);
394 	record->offset = (le64_to_cpu(tmp) & 0xffffffffffff);
395 	i += 6;
396 
397 	record->mem_channel = buff[i++];
398 	record->mcumc_id = buff[i++];
399 
400 	memcpy(&tmp, buff + i,  6);
401 	record->retired_page = (le64_to_cpu(tmp) & 0xffffffffffff);
402 }
403 
404 /*
405  * When reaching end of EEPROM memory jump back to 0 record address
406  * When next record access will go beyond EEPROM page boundary modify bits A17/A8
407  * in I2C selector to go to next page
408  */
409 static uint32_t __correct_eeprom_dest_address(uint32_t curr_address)
410 {
411 	uint32_t next_address = curr_address + EEPROM_TABLE_RECORD_SIZE;
412 
413 	/* When all EEPROM memory used jump back to 0 address */
414 	if (next_address > EEPROM_SIZE_BYTES) {
415 		DRM_INFO("Reached end of EEPROM memory, jumping to 0 "
416 			 "and overriding old record");
417 		return EEPROM_RECORD_START;
418 	}
419 
420 	/*
421 	 * To check if we overflow page boundary  compare next address with
422 	 * current and see if bits 17/8 of the EEPROM address will change
423 	 * If they do start from the next 256b page
424 	 *
425 	 * https://www.st.com/resource/en/datasheet/m24m02-dr.pdf sec. 5.1.2
426 	 */
427 	if ((curr_address & EEPROM_ADDR_MSB_MASK) != (next_address & EEPROM_ADDR_MSB_MASK)) {
428 		DRM_DEBUG_DRIVER("Reached end of EEPROM memory page, jumping to next: %lx",
429 				(next_address & EEPROM_ADDR_MSB_MASK));
430 
431 		return  (next_address & EEPROM_ADDR_MSB_MASK);
432 	}
433 
434 	return curr_address;
435 }
436 
437 int amdgpu_ras_eeprom_check_err_threshold(
438 				struct amdgpu_ras_eeprom_control *control,
439 				bool *exceed_err_limit)
440 {
441 	struct amdgpu_device *adev = to_amdgpu_device(control);
442 	unsigned char buff[EEPROM_ADDRESS_SIZE +
443 			EEPROM_TABLE_HEADER_SIZE] = { 0 };
444 	struct amdgpu_ras_eeprom_table_header *hdr = &control->tbl_hdr;
445 	struct i2c_msg msg = {
446 			.addr = control->i2c_address,
447 			.flags = I2C_M_RD,
448 			.len = EEPROM_ADDRESS_SIZE + EEPROM_TABLE_HEADER_SIZE,
449 			.buf = buff,
450 	};
451 	int ret;
452 
453 	*exceed_err_limit = false;
454 
455 	if (!__is_ras_eeprom_supported(adev))
456 		return 0;
457 
458 	/* read EEPROM table header */
459 	mutex_lock(&control->tbl_mutex);
460 	ret = i2c_transfer(&adev->pm.smu_i2c, &msg, 1);
461 	if (ret < 1) {
462 		dev_err(adev->dev, "Failed to read EEPROM table header.\n");
463 		goto err;
464 	}
465 
466 	__decode_table_header_from_buff(hdr, &buff[2]);
467 
468 	if (hdr->header == EEPROM_TABLE_HDR_BAD) {
469 		dev_warn(adev->dev, "This GPU is in BAD status.");
470 		dev_warn(adev->dev, "Please retire it or setting one bigger "
471 				"threshold value when reloading driver.\n");
472 		*exceed_err_limit = true;
473 	}
474 
475 err:
476 	mutex_unlock(&control->tbl_mutex);
477 	return 0;
478 }
479 
480 int amdgpu_ras_eeprom_process_recods(struct amdgpu_ras_eeprom_control *control,
481 					    struct eeprom_table_record *records,
482 					    bool write,
483 					    int num)
484 {
485 	int i, ret = 0;
486 	struct i2c_msg *msgs, *msg;
487 	unsigned char *buffs, *buff;
488 	struct eeprom_table_record *record;
489 	struct amdgpu_device *adev = to_amdgpu_device(control);
490 	struct amdgpu_ras *ras = amdgpu_ras_get_context(adev);
491 
492 	if (!__is_ras_eeprom_supported(adev))
493 		return 0;
494 
495 	buffs = kcalloc(num, EEPROM_ADDRESS_SIZE + EEPROM_TABLE_RECORD_SIZE,
496 			 GFP_KERNEL);
497 	if (!buffs)
498 		return -ENOMEM;
499 
500 	mutex_lock(&control->tbl_mutex);
501 
502 	msgs = kcalloc(num, sizeof(*msgs), GFP_KERNEL);
503 	if (!msgs) {
504 		ret = -ENOMEM;
505 		goto free_buff;
506 	}
507 
508 	/*
509 	 * If saved bad pages number exceeds the bad page threshold for
510 	 * the whole VRAM, update table header to mark the BAD GPU tag
511 	 * and schedule one ras recovery after eeprom write is done,
512 	 * this can avoid the missing for latest records.
513 	 *
514 	 * This new header will be picked up and checked in the bootup
515 	 * by ras recovery, which may break bootup process to notify
516 	 * user this GPU is in bad state and to retire such GPU for
517 	 * further check.
518 	 */
519 	if (write && (amdgpu_bad_page_threshold != 0) &&
520 		((control->num_recs + num) >= ras->bad_page_cnt_threshold)) {
521 		dev_warn(adev->dev,
522 			"Saved bad pages(%d) reaches threshold value(%d).\n",
523 			control->num_recs + num, ras->bad_page_cnt_threshold);
524 		control->tbl_hdr.header = EEPROM_TABLE_HDR_BAD;
525 	}
526 
527 	/* In case of overflow just start from beginning to not lose newest records */
528 	if (write && (control->next_addr + EEPROM_TABLE_RECORD_SIZE * num > EEPROM_SIZE_BYTES))
529 		control->next_addr = EEPROM_RECORD_START;
530 
531 	/*
532 	 * TODO Currently makes EEPROM writes for each record, this creates
533 	 * internal fragmentation. Optimized the code to do full page write of
534 	 * 256b
535 	 */
536 	for (i = 0; i < num; i++) {
537 		buff = &buffs[i * (EEPROM_ADDRESS_SIZE + EEPROM_TABLE_RECORD_SIZE)];
538 		record = &records[i];
539 		msg = &msgs[i];
540 
541 		control->next_addr = __correct_eeprom_dest_address(control->next_addr);
542 
543 		/*
544 		 * Update bits 16,17 of EEPROM address in I2C address by setting them
545 		 * to bits 1,2 of Device address byte
546 		 */
547 		msg->addr = control->i2c_address |
548 			        ((control->next_addr & EEPROM_ADDR_MSB_MASK) >> 15);
549 		msg->flags	= write ? 0 : I2C_M_RD;
550 		msg->len	= EEPROM_ADDRESS_SIZE + EEPROM_TABLE_RECORD_SIZE;
551 		msg->buf	= buff;
552 
553 		/* Insert the EEPROM dest addess, bits 0-15 */
554 		buff[0] = ((control->next_addr >> 8) & 0xff);
555 		buff[1] = (control->next_addr & 0xff);
556 
557 		/* EEPROM table content is stored in LE format */
558 		if (write)
559 			__encode_table_record_to_buff(control, record, buff + EEPROM_ADDRESS_SIZE);
560 
561 		/*
562 		 * The destination EEPROM address might need to be corrected to account
563 		 * for page or entire memory wrapping
564 		 */
565 		control->next_addr += EEPROM_TABLE_RECORD_SIZE;
566 	}
567 
568 	/* i2c may be unstable in gpu reset */
569 	down_read(&adev->reset_sem);
570 	ret = i2c_transfer(&adev->pm.smu_i2c, msgs, num);
571 	up_read(&adev->reset_sem);
572 
573 	if (ret < 1) {
574 		DRM_ERROR("Failed to process EEPROM table records, ret:%d", ret);
575 
576 		/* TODO Restore prev next EEPROM address ? */
577 		goto free_msgs;
578 	}
579 
580 
581 	if (!write) {
582 		for (i = 0; i < num; i++) {
583 			buff = &buffs[i*(EEPROM_ADDRESS_SIZE + EEPROM_TABLE_RECORD_SIZE)];
584 			record = &records[i];
585 
586 			__decode_table_record_from_buff(control, record, buff + EEPROM_ADDRESS_SIZE);
587 		}
588 	}
589 
590 	if (write) {
591 		uint32_t old_hdr_byte_sum = __calc_hdr_byte_sum(control);
592 
593 		/*
594 		 * Update table header with size and CRC and account for table
595 		 * wrap around where the assumption is that we treat it as empty
596 		 * table
597 		 *
598 		 * TODO - Check the assumption is correct
599 		 */
600 		control->num_recs += num;
601 		control->num_recs %= EEPROM_MAX_RECORD_NUM;
602 		control->tbl_hdr.tbl_size += EEPROM_TABLE_RECORD_SIZE * num;
603 		if (control->tbl_hdr.tbl_size > EEPROM_SIZE_BYTES)
604 			control->tbl_hdr.tbl_size = EEPROM_TABLE_HEADER_SIZE +
605 			control->num_recs * EEPROM_TABLE_RECORD_SIZE;
606 
607 		__update_tbl_checksum(control, records, num, old_hdr_byte_sum);
608 
609 		__update_table_header(control, buffs);
610 	} else if (!__validate_tbl_checksum(control, records, num)) {
611 		DRM_WARN("EEPROM Table checksum mismatch!");
612 		/* TODO Uncomment when EEPROM read/write is relliable */
613 		/* ret = -EIO; */
614 	}
615 
616 free_msgs:
617 	kfree(msgs);
618 
619 free_buff:
620 	kfree(buffs);
621 
622 	mutex_unlock(&control->tbl_mutex);
623 
624 	return ret == num ? 0 : -EIO;
625 }
626 
627 inline uint32_t amdgpu_ras_eeprom_get_record_max_length(void)
628 {
629 	return EEPROM_MAX_RECORD_NUM;
630 }
631 
632 /* Used for testing if bugs encountered */
633 #if 0
634 void amdgpu_ras_eeprom_test(struct amdgpu_ras_eeprom_control *control)
635 {
636 	int i;
637 	struct eeprom_table_record *recs = kcalloc(1, sizeof(*recs), GFP_KERNEL);
638 
639 	if (!recs)
640 		return;
641 
642 	for (i = 0; i < 1 ; i++) {
643 		recs[i].address = 0xdeadbeef;
644 		recs[i].retired_page = i;
645 	}
646 
647 	if (!amdgpu_ras_eeprom_process_recods(control, recs, true, 1)) {
648 
649 		memset(recs, 0, sizeof(*recs) * 1);
650 
651 		control->next_addr = EEPROM_RECORD_START;
652 
653 		if (!amdgpu_ras_eeprom_process_recods(control, recs, false, 1)) {
654 			for (i = 0; i < 1; i++)
655 				DRM_INFO("rec.address :0x%llx, rec.retired_page :%llu",
656 					 recs[i].address, recs[i].retired_page);
657 		} else
658 			DRM_ERROR("Failed in reading from table");
659 
660 	} else
661 		DRM_ERROR("Failed in writing to table");
662 }
663 #endif
664