xref: /linux/drivers/gpu/drm/amd/ras/rascore/ras_eeprom.c (revision 6dfafbd0299a60bfb5d5e277fdf100037c7ded07)

// SPDX-License-Identifier: MIT
/*
 * Copyright 2025 Advanced Micro Devices, Inc.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
 * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR
 * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
 * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
 * OTHER DEALINGS IN THE SOFTWARE.
 *
 */

#include "ras_eeprom.h"
#include "ras.h"

/* These are memory addresses as would be seen by one or more EEPROM
 * chips strung on the I2C bus, usually by manipulating pins 1-3 of a
 * set of EEPROM devices. They form a continuous memory space.
 *
 * The I2C device address includes the device type identifier, 1010b,
 * which is a reserved value and indicates that this is an I2C EEPROM
 * device. It also includes the top 3 bits of the 19 bit EEPROM memory
 * address, namely bits 18, 17, and 16. This makes up the 7 bit
 * address sent on the I2C bus with bit 0 being the direction bit,
 * which is not represented here, and sent by the hardware directly.
 *
 * For instance,
 *   50h = 1010000b => device type identifier 1010b, bits 18:16 = 000b, address 0.
 *   54h = 1010100b => --"--, bits 18:16 = 100b, address 40000h.
 *   56h = 1010110b => --"--, bits 18:16 = 110b, address 60000h.
 * Depending on the size of the I2C EEPROM device(s), bits 18:16 may
 * address memory in a device or a device on the I2C bus, depending on
 * the status of pins 1-3.
 *
 * The RAS table lives either at address 0 or address 40000h of EEPROM.
 */
#define EEPROM_I2C_MADDR_0      0x0
#define EEPROM_I2C_MADDR_4      0x40000

#define EEPROM_PAGE_BITS   8
#define EEPROM_PAGE_SIZE   (1U << EEPROM_PAGE_BITS)
#define EEPROM_PAGE_MASK   (EEPROM_PAGE_SIZE - 1)

#define EEPROM_OFFSET_SIZE 2
#define MAKE_I2C_ADDR(_aa) ((0xA << 3) | (((_aa) >> 16) & 0xF))

/*
 * The 2 macros bellow represent the actual size in bytes that
 * those entities occupy in the EEPROM memory.
 * RAS_TABLE_RECORD_SIZE is different than sizeof(eeprom_umc_record) which
 * uses uint64 to store 6b fields such as retired_page.
 */
#define RAS_TABLE_HEADER_SIZE   20
#define RAS_TABLE_RECORD_SIZE   24

/* Table hdr is 'AMDR' */
#define RAS_TABLE_HDR_VAL       0x414d4452

/* Bad GPU tag ‘BADG’ */
#define RAS_TABLE_HDR_BAD       0x42414447

/*
 * EEPROM Table structure v1
 * ---------------------------------
 * |                               |
 * |     EEPROM TABLE HEADER       |
 * |      ( size 20 Bytes )        |
 * |                               |
 * ---------------------------------
 * |                               |
 * |    BAD PAGE RECORD AREA       |
 * |                               |
 * ---------------------------------
 */

/* Assume 2-Mbit size EEPROM and take up the whole space. */
#define RAS_TBL_SIZE_BYTES      (256 * 1024)
#define RAS_TABLE_START         0
#define RAS_HDR_START           RAS_TABLE_START
#define RAS_RECORD_START        (RAS_HDR_START + RAS_TABLE_HEADER_SIZE)
#define RAS_MAX_RECORD_COUNT    ((RAS_TBL_SIZE_BYTES - RAS_TABLE_HEADER_SIZE) \
				 / RAS_TABLE_RECORD_SIZE)

/*
 * EEPROM Table structrue v2.1
 * ---------------------------------
 * |                               |
 * |     EEPROM TABLE HEADER       |
 * |      ( size 20 Bytes )        |
 * |                               |
 * ---------------------------------
 * |                               |
 * |     EEPROM TABLE RAS INFO     |
 * | (available info size 4 Bytes) |
 * |  ( reserved size 252 Bytes )  |
 * |                               |
 * ---------------------------------
 * |                               |
 * |     BAD PAGE RECORD AREA      |
 * |                               |
 * ---------------------------------
 */

/* EEPROM Table V2_1 */
#define RAS_TABLE_V2_1_INFO_SIZE       256
#define RAS_TABLE_V2_1_INFO_START      RAS_TABLE_HEADER_SIZE
#define RAS_RECORD_START_V2_1          (RAS_HDR_START + RAS_TABLE_HEADER_SIZE + \
					RAS_TABLE_V2_1_INFO_SIZE)
#define RAS_MAX_RECORD_COUNT_V2_1      ((RAS_TBL_SIZE_BYTES - RAS_TABLE_HEADER_SIZE - \
					RAS_TABLE_V2_1_INFO_SIZE) \
					/ RAS_TABLE_RECORD_SIZE)

/* Given a zero-based index of an EEPROM RAS record, yields the EEPROM
 * offset off of RAS_TABLE_START.  That is, this is something you can
 * add to control->i2c_address, and then tell I2C layer to read
 * from/write to there. _N is the so called absolute index,
 * because it starts right after the table header.
 */
#define RAS_INDEX_TO_OFFSET(_C, _N) ((_C)->ras_record_offset + \
				     (_N) * RAS_TABLE_RECORD_SIZE)

#define RAS_OFFSET_TO_INDEX(_C, _O) (((_O) - \
				      (_C)->ras_record_offset) / RAS_TABLE_RECORD_SIZE)

/* Given a 0-based relative record index, 0, 1, 2, ..., etc., off
 * of "fri", return the absolute record index off of the end of
 * the table header.
 */
#define RAS_RI_TO_AI(_C, _I) (((_I) + (_C)->ras_fri) % \
			      (_C)->ras_max_record_count)

#define RAS_NUM_RECS(_tbl_hdr)  (((_tbl_hdr)->tbl_size - \
				  RAS_TABLE_HEADER_SIZE) / RAS_TABLE_RECORD_SIZE)

#define RAS_NUM_RECS_V2_1(_tbl_hdr)  (((_tbl_hdr)->tbl_size - \
				       RAS_TABLE_HEADER_SIZE - \
				       RAS_TABLE_V2_1_INFO_SIZE) / RAS_TABLE_RECORD_SIZE)

#define to_ras_core_context(x) (container_of(x, struct ras_core_context, ras_eeprom))

static bool __is_ras_eeprom_supported(struct ras_core_context *ras_core)
{
	return ras_core->ras_eeprom_supported;
}

static bool __get_eeprom_i2c_addr(struct ras_core_context *ras_core,
				  struct ras_eeprom_control *control)
{
	int ret = -EINVAL;

	if (control->sys_func &&
		control->sys_func->update_eeprom_i2c_config)
		ret = control->sys_func->update_eeprom_i2c_config(ras_core);
	else
		RAS_DEV_WARN(ras_core->dev,
			"No eeprom i2c system config!\n");

	return !ret ? true : false;
}

static int __ras_eeprom_xfer(struct ras_core_context *ras_core, u32 eeprom_addr,
				u8 *eeprom_buf, u32 buf_size, bool read)
{
	struct ras_eeprom_control *control = &ras_core->ras_eeprom;
	int ret;

	if (control->sys_func && control->sys_func->eeprom_i2c_xfer) {
		ret = control->sys_func->eeprom_i2c_xfer(ras_core,
				eeprom_addr, eeprom_buf, buf_size, read);

		if ((ret > 0) && !read) {
			/* According to EEPROM specs the length of the
			 * self-writing cycle, tWR (tW), is 10 ms.
			 *
			 * TODO: Use polling on ACK, aka Acknowledge
			 * Polling, to minimize waiting for the
			 * internal write cycle to complete, as it is
			 * usually smaller than tWR (tW).
			 */
			msleep(10);
		}

		return ret;
	}

	RAS_DEV_ERR(ras_core->dev, "Error: No eeprom i2c system xfer function!\n");
	return -EINVAL;
}

static int __eeprom_xfer(struct ras_core_context *ras_core, u32 eeprom_addr,
			      u8 *eeprom_buf, u32 buf_size, bool read)
{
	u16 limit;
	u16 ps; /* Partial size */
	int res = 0, r;

	if (read)
		limit = ras_core->ras_eeprom.max_read_len;
	else
		limit = ras_core->ras_eeprom.max_write_len;

	if (limit && (limit <= EEPROM_OFFSET_SIZE)) {
		RAS_DEV_ERR(ras_core->dev,
				"maddr:0x%04X size:0x%02X:quirk max_%s_len must be > %d",
				eeprom_addr, buf_size,
				read ? "read" : "write", EEPROM_OFFSET_SIZE);
		return -EINVAL;
	}

	ras_core_down_gpu_reset_lock(ras_core);

	if (limit == 0) {
		res = __ras_eeprom_xfer(ras_core, eeprom_addr,
					eeprom_buf, buf_size, read);
	} else {
		/* The "limit" includes all data bytes sent/received,
		 * which would include the EEPROM_OFFSET_SIZE bytes.
		 * Account for them here.
		 */
		limit -= EEPROM_OFFSET_SIZE;
		for ( ; buf_size > 0;
			buf_size -= ps, eeprom_addr += ps, eeprom_buf += ps) {
			ps = (buf_size < limit) ? buf_size : limit;

			r = __ras_eeprom_xfer(ras_core, eeprom_addr,
						eeprom_buf, ps, read);
			if (r < 0)
				break;

			res += r;
		}
	}

	ras_core_up_gpu_reset_lock(ras_core);

	return res;
}

static int __eeprom_read(struct ras_core_context *ras_core,
			      u32 eeprom_addr, u8 *eeprom_buf, u32 bytes)
{
	return __eeprom_xfer(ras_core, eeprom_addr,
			   eeprom_buf, bytes, true);
}

static int __eeprom_write(struct ras_core_context *ras_core,
			       u32 eeprom_addr, u8 *eeprom_buf, u32 bytes)
{
	return __eeprom_xfer(ras_core, eeprom_addr,
			   eeprom_buf, bytes, false);
}

static void
__encode_table_header_to_buf(struct ras_eeprom_table_header *hdr,
			     unsigned char *buf)
{
	u32 *pp = (uint32_t *)buf;

	pp[0] = cpu_to_le32(hdr->header);
	pp[1] = cpu_to_le32(hdr->version);
	pp[2] = cpu_to_le32(hdr->first_rec_offset);
	pp[3] = cpu_to_le32(hdr->tbl_size);
	pp[4] = cpu_to_le32(hdr->checksum);
}

static void
__decode_table_header_from_buf(struct ras_eeprom_table_header *hdr,
			       unsigned char *buf)
{
	u32 *pp = (uint32_t *)buf;

	hdr->header	      = le32_to_cpu(pp[0]);
	hdr->version	      = le32_to_cpu(pp[1]);
	hdr->first_rec_offset = le32_to_cpu(pp[2]);
	hdr->tbl_size	      = le32_to_cpu(pp[3]);
	hdr->checksum	      = le32_to_cpu(pp[4]);
}

static int __write_table_header(struct ras_eeprom_control *control)
{
	u8 buf[RAS_TABLE_HEADER_SIZE];
	struct ras_core_context *ras_core = to_ras_core_context(control);
	int res;

	memset(buf, 0, sizeof(buf));
	__encode_table_header_to_buf(&control->tbl_hdr, buf);

	/* i2c may be unstable in gpu reset */
	res = __eeprom_write(ras_core,
				  control->i2c_address +
				  control->ras_header_offset,
				  buf, RAS_TABLE_HEADER_SIZE);

	if (res < 0) {
		RAS_DEV_ERR(ras_core->dev,
			"Failed to write EEPROM table header:%d\n", res);
	} else if (res < RAS_TABLE_HEADER_SIZE) {
		RAS_DEV_ERR(ras_core->dev,
			"Short write:%d out of %d\n", res, RAS_TABLE_HEADER_SIZE);
		res = -EIO;
	} else {
		res = 0;
	}

	return res;
}

static void
__encode_table_ras_info_to_buf(struct ras_eeprom_table_ras_info *rai,
			       unsigned char *buf)
{
	u32 *pp = (uint32_t *)buf;
	u32 tmp;

	tmp = ((uint32_t)(rai->rma_status) & 0xFF) |
	      (((uint32_t)(rai->health_percent) << 8) & 0xFF00) |
	      (((uint32_t)(rai->ecc_page_threshold) << 16) & 0xFFFF0000);
	pp[0] = cpu_to_le32(tmp);
}

static void
__decode_table_ras_info_from_buf(struct ras_eeprom_table_ras_info *rai,
				 unsigned char *buf)
{
	u32 *pp = (uint32_t *)buf;
	u32 tmp;

	tmp = le32_to_cpu(pp[0]);
	rai->rma_status = tmp & 0xFF;
	rai->health_percent = (tmp >> 8) & 0xFF;
	rai->ecc_page_threshold = (tmp >> 16) & 0xFFFF;
}

static int __write_table_ras_info(struct ras_eeprom_control *control)
{
	struct ras_core_context *ras_core = to_ras_core_context(control);
	u8 *buf;
	int res;

	buf = kzalloc(RAS_TABLE_V2_1_INFO_SIZE, GFP_KERNEL);
	if (!buf) {
		RAS_DEV_ERR(ras_core->dev,
			"Failed to alloc buf to write table ras info\n");
		return -ENOMEM;
	}

	__encode_table_ras_info_to_buf(&control->tbl_rai, buf);

	/* i2c may be unstable in gpu reset */
	res = __eeprom_write(ras_core,
				  control->i2c_address +
				  control->ras_info_offset,
				  buf, RAS_TABLE_V2_1_INFO_SIZE);

	if (res < 0) {
		RAS_DEV_ERR(ras_core->dev,
			"Failed to write EEPROM table ras info:%d\n", res);
	} else if (res < RAS_TABLE_V2_1_INFO_SIZE) {
		RAS_DEV_ERR(ras_core->dev,
			"Short write:%d out of %d\n", res, RAS_TABLE_V2_1_INFO_SIZE);
		res = -EIO;
	} else {
		res = 0;
	}

	kfree(buf);

	return res;
}

static u8 __calc_hdr_byte_sum(const struct ras_eeprom_control *control)
{
	int ii;
	u8  *pp, csum;
	u32 sz;

	/* Header checksum, skip checksum field in the calculation */
	sz = sizeof(control->tbl_hdr) - sizeof(control->tbl_hdr.checksum);
	pp = (u8 *) &control->tbl_hdr;
	csum = 0;
	for (ii = 0; ii < sz; ii++, pp++)
		csum += *pp;

	return csum;
}

static u8 __calc_ras_info_byte_sum(const struct ras_eeprom_control *control)
{
	int ii;
	u8  *pp, csum;
	u32 sz;

	sz = sizeof(control->tbl_rai);
	pp = (u8 *) &control->tbl_rai;
	csum = 0;
	for (ii = 0; ii < sz; ii++, pp++)
		csum += *pp;

	return csum;
}

static int ras_eeprom_correct_header_tag(
	struct ras_eeprom_control *control,
	uint32_t header)
{
	struct ras_eeprom_table_header *hdr = &control->tbl_hdr;
	u8 *hh;
	int res;
	u8 csum;

	csum = -hdr->checksum;

	hh = (void *) &hdr->header;
	csum -= (hh[0] + hh[1] + hh[2] + hh[3]);
	hh = (void *) &header;
	csum += hh[0] + hh[1] + hh[2] + hh[3];
	csum = -csum;
	mutex_lock(&control->ras_tbl_mutex);
	hdr->header = header;
	hdr->checksum = csum;
	res = __write_table_header(control);
	mutex_unlock(&control->ras_tbl_mutex);

	return res;
}

static void ras_set_eeprom_table_version(struct ras_eeprom_control *control)
{
	struct ras_eeprom_table_header *hdr = &control->tbl_hdr;

	hdr->version = RAS_TABLE_VER_V3;
}

int ras_eeprom_reset_table(struct ras_core_context *ras_core)
{
	struct ras_eeprom_control *control = &ras_core->ras_eeprom;
	struct ras_eeprom_table_header *hdr = &control->tbl_hdr;
	struct ras_eeprom_table_ras_info *rai = &control->tbl_rai;
	u8 csum;
	int res;

	mutex_lock(&control->ras_tbl_mutex);

	hdr->header = RAS_TABLE_HDR_VAL;
	ras_set_eeprom_table_version(control);

	if (hdr->version >= RAS_TABLE_VER_V2_1) {
		hdr->first_rec_offset = RAS_RECORD_START_V2_1;
		hdr->tbl_size = RAS_TABLE_HEADER_SIZE +
				RAS_TABLE_V2_1_INFO_SIZE;
		rai->rma_status = RAS_GPU_HEALTH_USABLE;
		/**
		 * GPU health represented as a percentage.
		 * 0 means worst health, 100 means fully health.
		 */
		rai->health_percent = 100;
		/* ecc_page_threshold = 0 means disable bad page retirement */
		rai->ecc_page_threshold = control->record_threshold_count;
	} else {
		hdr->first_rec_offset = RAS_RECORD_START;
		hdr->tbl_size = RAS_TABLE_HEADER_SIZE;
	}

	csum = __calc_hdr_byte_sum(control);
	if (hdr->version >= RAS_TABLE_VER_V2_1)
		csum += __calc_ras_info_byte_sum(control);
	csum = -csum;
	hdr->checksum = csum;
	res = __write_table_header(control);
	if (!res && hdr->version > RAS_TABLE_VER_V1)
		res = __write_table_ras_info(control);

	control->ras_num_recs = 0;
	control->ras_fri = 0;

	control->bad_channel_bitmap = 0;
	ras_core_event_notify(ras_core, RAS_EVENT_ID__UPDATE_BAD_PAGE_NUM,
		&control->ras_num_recs);
	ras_core_event_notify(ras_core, RAS_EVENT_ID__UPDATE_BAD_CHANNEL_BITMAP,
		&control->bad_channel_bitmap);
	control->update_channel_flag = false;

	mutex_unlock(&control->ras_tbl_mutex);

	return res;
}

static void
__encode_table_record_to_buf(struct ras_eeprom_control *control,
			     struct eeprom_umc_record *record,
			     unsigned char *buf)
{
	__le64 tmp = 0;
	int i = 0;

	/* Next are all record fields according to EEPROM page spec in LE foramt */
	buf[i++] = record->err_type;

	buf[i++] = record->bank;

	tmp = cpu_to_le64(record->ts);
	memcpy(buf + i, &tmp, 8);
	i += 8;

	tmp = cpu_to_le64((record->offset & 0xffffffffffff));
	memcpy(buf + i, &tmp, 6);
	i += 6;

	buf[i++] = record->mem_channel;
	buf[i++] = record->mcumc_id;

	tmp = cpu_to_le64((record->retired_row_pfn & 0xffffffffffff));
	memcpy(buf + i, &tmp, 6);
}

static void
__decode_table_record_from_buf(struct ras_eeprom_control *control,
			       struct eeprom_umc_record *record,
			       unsigned char *buf)
{
	__le64 tmp = 0;
	int i =  0;

	/* Next are all record fields according to EEPROM page spec in LE foramt */
	record->err_type = buf[i++];

	record->bank = buf[i++];

	memcpy(&tmp, buf + i, 8);
	record->ts = le64_to_cpu(tmp);
	i += 8;

	memcpy(&tmp, buf + i, 6);
	record->offset = (le64_to_cpu(tmp) & 0xffffffffffff);
	i += 6;

	record->mem_channel = buf[i++];
	record->mcumc_id = buf[i++];

	memcpy(&tmp, buf + i,  6);
	record->retired_row_pfn = (le64_to_cpu(tmp) & 0xffffffffffff);
}

bool ras_eeprom_check_safety_watermark(struct ras_core_context *ras_core)
{
	struct ras_eeprom_control *control = &ras_core->ras_eeprom;
	bool ret = false;
	int bad_page_count;

	if (!__is_ras_eeprom_supported(ras_core) ||
	    !control->record_threshold_config)
		return false;

	bad_page_count = ras_umc_get_badpage_count(ras_core);
	if (control->tbl_hdr.header == RAS_TABLE_HDR_BAD) {
		if (bad_page_count > control->record_threshold_count)
			RAS_DEV_WARN(ras_core->dev, "RAS records:%d exceed threshold:%d",
				bad_page_count, control->record_threshold_count);

		if ((control->record_threshold_config == WARN_NONSTOP_OVER_THRESHOLD) ||
			(control->record_threshold_config == NONSTOP_OVER_THRESHOLD)) {
			RAS_DEV_WARN(ras_core->dev,
				"Please consult AMD Service Action Guide (SAG) for appropriate service procedures.\n");
			ret = false;
		} else {
			ras_core->is_rma = true;
			RAS_DEV_WARN(ras_core->dev,
				"Please consider adjusting the customized threshold.\n");
			ret = true;
		}
	}

	return ret;
}

/**
 * __ras_eeprom_write -- write indexed from buffer to EEPROM
 * @control: pointer to control structure
 * @buf: pointer to buffer containing data to write
 * @fri: start writing at this index
 * @num: number of records to write
 *
 * The caller must hold the table mutex in @control.
 * Return 0 on success, -errno otherwise.
 */
static int __ras_eeprom_write(struct ras_eeprom_control *control,
			      u8 *buf, const u32 fri, const u32 num)
{
	struct ras_core_context *ras_core = to_ras_core_context(control);
	u32 buf_size;
	int res;

	/* i2c may be unstable in gpu reset */
	buf_size = num * RAS_TABLE_RECORD_SIZE;
	res = __eeprom_write(ras_core,
			       control->i2c_address + RAS_INDEX_TO_OFFSET(control, fri),
			       buf, buf_size);
	if (res < 0) {
		RAS_DEV_ERR(ras_core->dev,
			"Writing %d EEPROM table records error:%d\n", num, res);
	} else if (res < buf_size) {
		/* Short write, return error.*/
		RAS_DEV_ERR(ras_core->dev,
			"Wrote %d records out of %d\n",
			(res/RAS_TABLE_RECORD_SIZE), num);
		res = -EIO;
	} else {
		res = 0;
	}

	return res;
}

static int ras_eeprom_append_table(struct ras_eeprom_control *control,
				   struct eeprom_umc_record *record,
				   const u32 num)
{
	u32 a, b, i;
	u8 *buf, *pp;
	int res;

	buf = kcalloc(num, RAS_TABLE_RECORD_SIZE, GFP_KERNEL);
	if (!buf)
		return -ENOMEM;

	/* Encode all of them in one go.
	 */
	pp = buf;
	for (i = 0; i < num; i++, pp += RAS_TABLE_RECORD_SIZE) {
		__encode_table_record_to_buf(control, &record[i], pp);

		/* update bad channel bitmap */
		if ((record[i].mem_channel < BITS_PER_TYPE(control->bad_channel_bitmap)) &&
		    !(control->bad_channel_bitmap & (1 << record[i].mem_channel))) {
			control->bad_channel_bitmap |= 1 << record[i].mem_channel;
			control->update_channel_flag = true;
		}
	}

	/* a, first record index to write into.
	 * b, last record index to write into.
	 * a = first index to read (fri) + number of records in the table,
	 * b = a + @num - 1.
	 * Let N = control->ras_max_num_record_count, then we have,
	 * case 0: 0 <= a <= b < N,
	 *   just append @num records starting at a;
	 * case 1: 0 <= a < N <= b,
	 *   append (N - a) records starting at a, and
	 *   append the remainder,  b % N + 1, starting at 0.
	 * case 2: 0 <= fri < N <= a <= b, then modulo N we get two subcases,
	 * case 2a: 0 <= a <= b < N
	 *   append num records starting at a; and fix fri if b overwrote it,
	 *   and since a <= b, if b overwrote it then a must've also,
	 *   and if b didn't overwrite it, then a didn't also.
	 * case 2b: 0 <= b < a < N
	 *   write num records starting at a, which wraps around 0=N
	 *   and overwrite fri unconditionally. Now from case 2a,
	 *   this means that b eclipsed fri to overwrite it and wrap
	 *   around 0 again, i.e. b = 2N+r pre modulo N, so we unconditionally
	 *   set fri = b + 1 (mod N).
	 * Now, since fri is updated in every case, except the trivial case 0,
	 * the number of records present in the table after writing, is,
	 * num_recs - 1 = b - fri (mod N), and we take the positive value,
	 * by adding an arbitrary multiple of N before taking the modulo N
	 * as shown below.
	 */
	a = control->ras_fri + control->ras_num_recs;
	b = a + num  - 1;
	if (b < control->ras_max_record_count) {
		res = __ras_eeprom_write(control, buf, a, num);
	} else if (a < control->ras_max_record_count) {
		u32 g0, g1;

		g0 = control->ras_max_record_count - a;
		g1 = b % control->ras_max_record_count + 1;
		res = __ras_eeprom_write(control, buf, a, g0);
		if (res)
			goto Out;
		res = __ras_eeprom_write(control,
						buf + g0 * RAS_TABLE_RECORD_SIZE,
						0, g1);
		if (res)
			goto Out;
		if (g1 > control->ras_fri)
			control->ras_fri = g1 % control->ras_max_record_count;
	} else {
		a %= control->ras_max_record_count;
		b %= control->ras_max_record_count;

		if (a <= b) {
			/* Note that, b - a + 1 = num. */
			res = __ras_eeprom_write(control, buf, a, num);
			if (res)
				goto Out;
			if (b >= control->ras_fri)
				control->ras_fri = (b + 1) % control->ras_max_record_count;
		} else {
			u32 g0, g1;

			/* b < a, which means, we write from
			 * a to the end of the table, and from
			 * the start of the table to b.
			 */
			g0 = control->ras_max_record_count - a;
			g1 = b + 1;
			res = __ras_eeprom_write(control, buf, a, g0);
			if (res)
				goto Out;
			res = __ras_eeprom_write(control,
						 buf + g0 * RAS_TABLE_RECORD_SIZE, 0, g1);
			if (res)
				goto Out;
			control->ras_fri = g1 % control->ras_max_record_count;
		}
	}
	control->ras_num_recs = 1 +
		(control->ras_max_record_count + b - control->ras_fri)
		% control->ras_max_record_count;
Out:
	kfree(buf);
	return res;
}

static int ras_eeprom_update_header(struct ras_eeprom_control *control)
{
	struct ras_core_context *ras_core = to_ras_core_context(control);
	int threshold_config = control->record_threshold_config;
	u8 *buf, *pp, csum;
	u32 buf_size;
	int bad_page_count;
	int res;

	bad_page_count = ras_umc_get_badpage_count(ras_core);
	/* Modify the header if it exceeds.
	 */
	if (threshold_config != 0 &&
		bad_page_count > control->record_threshold_count) {
		RAS_DEV_WARN(ras_core->dev,
			"Saved bad pages %d reaches threshold value %d\n",
			bad_page_count, control->record_threshold_count);
		control->tbl_hdr.header = RAS_TABLE_HDR_BAD;
		if (control->tbl_hdr.version >= RAS_TABLE_VER_V2_1) {
			control->tbl_rai.rma_status = RAS_GPU_RETIRED__ECC_REACH_THRESHOLD;
			control->tbl_rai.health_percent = 0;
		}

		if ((threshold_config != WARN_NONSTOP_OVER_THRESHOLD) &&
			(threshold_config != NONSTOP_OVER_THRESHOLD))
			ras_core->is_rma = true;

		/* ignore the -ENOTSUPP return value */
		ras_core_event_notify(ras_core, RAS_EVENT_ID__DEVICE_RMA, NULL);
	}

	if (control->tbl_hdr.version >= RAS_TABLE_VER_V2_1)
		control->tbl_hdr.tbl_size = RAS_TABLE_HEADER_SIZE +
					    RAS_TABLE_V2_1_INFO_SIZE +
					    control->ras_num_recs * RAS_TABLE_RECORD_SIZE;
	else
		control->tbl_hdr.tbl_size = RAS_TABLE_HEADER_SIZE +
					    control->ras_num_recs * RAS_TABLE_RECORD_SIZE;
	control->tbl_hdr.checksum = 0;

	buf_size = control->ras_num_recs * RAS_TABLE_RECORD_SIZE;
	buf = kcalloc(control->ras_num_recs, RAS_TABLE_RECORD_SIZE, GFP_KERNEL);
	if (!buf) {
		RAS_DEV_ERR(ras_core->dev,
			"allocating memory for table of size %d bytes failed\n",
			control->tbl_hdr.tbl_size);
		res = -ENOMEM;
		goto Out;
	}

	res = __eeprom_read(ras_core,
			      control->i2c_address +
			      control->ras_record_offset,
			      buf, buf_size);
	if (res < 0) {
		RAS_DEV_ERR(ras_core->dev,
			"EEPROM failed reading records:%d\n", res);
		goto Out;
	} else if (res < buf_size) {
		RAS_DEV_ERR(ras_core->dev,
			"EEPROM read %d out of %d bytes\n", res, buf_size);
		res = -EIO;
		goto Out;
	}

	/**
	 * bad page records have been stored in eeprom,
	 * now calculate gpu health percent
	 */
	if (threshold_config != 0 &&
	    control->tbl_hdr.version >= RAS_TABLE_VER_V2_1 &&
	    bad_page_count <= control->record_threshold_count)
		control->tbl_rai.health_percent = ((control->record_threshold_count -
			bad_page_count) * 100) / control->record_threshold_count;

	/* Recalc the checksum.
	 */
	csum = 0;
	for (pp = buf; pp < buf + buf_size; pp++)
		csum += *pp;

	csum += __calc_hdr_byte_sum(control);
	if (control->tbl_hdr.version >= RAS_TABLE_VER_V2_1)
		csum += __calc_ras_info_byte_sum(control);
	/* avoid sign extension when assigning to "checksum" */
	csum = -csum;
	control->tbl_hdr.checksum = csum;
	res = __write_table_header(control);
	if (!res && control->tbl_hdr.version > RAS_TABLE_VER_V1)
		res = __write_table_ras_info(control);
Out:
	kfree(buf);
	return res;
}

/**
 * ras_core_eeprom_append -- append records to the EEPROM RAS table
 * @control: pointer to control structure
 * @record: array of records to append
 * @num: number of records in @record array
 *
 * Append @num records to the table, calculate the checksum and write
 * the table back to EEPROM. The maximum number of records that
 * can be appended is between 1 and control->ras_max_record_count,
 * regardless of how many records are already stored in the table.
 *
 * Return 0 on success or if EEPROM is not supported, -errno on error.
 */
int ras_eeprom_append(struct ras_core_context *ras_core,
			   struct eeprom_umc_record *record, const u32 num)
{
	struct ras_eeprom_control *control = &ras_core->ras_eeprom;
	int res;

	if (!__is_ras_eeprom_supported(ras_core))
		return 0;

	if (num == 0) {
		RAS_DEV_ERR(ras_core->dev, "will not append 0 records\n");
		return -EINVAL;
	} else if ((num + control->ras_num_recs) > control->ras_max_record_count) {
		RAS_DEV_ERR(ras_core->dev,
			"cannot append %d records than the size of table %d\n",
			num, control->ras_max_record_count);
		return -EINVAL;
	}

	mutex_lock(&control->ras_tbl_mutex);
	res = ras_eeprom_append_table(control, record, num);
	if (!res)
		res = ras_eeprom_update_header(control);

	mutex_unlock(&control->ras_tbl_mutex);

	return res;
}

/**
 * __ras_eeprom_read -- read indexed from EEPROM into buffer
 * @control: pointer to control structure
 * @buf: pointer to buffer to read into
 * @fri: first record index, start reading at this index, absolute index
 * @num: number of records to read
 *
 * The caller must hold the table mutex in @control.
 * Return 0 on success, -errno otherwise.
 */
static int __ras_eeprom_read(struct ras_eeprom_control *control,
			     u8 *buf, const u32 fri, const u32 num)
{
	struct ras_core_context *ras_core = to_ras_core_context(control);
	u32 buf_size;
	int res;

	/* i2c may be unstable in gpu reset */
	buf_size = num * RAS_TABLE_RECORD_SIZE;
	res = __eeprom_read(ras_core,
			      control->i2c_address +
			      RAS_INDEX_TO_OFFSET(control, fri),
			      buf, buf_size);
	if (res < 0) {
		RAS_DEV_ERR(ras_core->dev,
			"Reading %d EEPROM table records error:%d\n", num, res);
	} else if (res < buf_size) {
		/* Short read, return error.
		 */
		RAS_DEV_ERR(ras_core->dev,
			"Read %d records out of %d\n",
			(res/RAS_TABLE_RECORD_SIZE), num);
		res = -EIO;
	} else {
		res = 0;
	}

	return res;
}

int ras_eeprom_read(struct ras_core_context *ras_core,
			 struct eeprom_umc_record *record, const u32 num)
{
	struct ras_eeprom_control *control = &ras_core->ras_eeprom;
	int i, res;
	u8 *buf, *pp;
	u32 g0, g1;

	if (!__is_ras_eeprom_supported(ras_core))
		return 0;

	if (num == 0) {
		RAS_DEV_ERR(ras_core->dev, "will not read 0 records\n");
		return -EINVAL;
	} else if (num > control->ras_num_recs) {
		RAS_DEV_ERR(ras_core->dev,
			"too many records to read:%d available:%d\n",
			num, control->ras_num_recs);
		return -EINVAL;
	}

	buf = kcalloc(num, RAS_TABLE_RECORD_SIZE, GFP_KERNEL);
	if (!buf)
		return -ENOMEM;

	/* Determine how many records to read, from the first record
	 * index, fri, to the end of the table, and from the beginning
	 * of the table, such that the total number of records is
	 * @num, and we handle wrap around when fri > 0 and
	 * fri + num > RAS_MAX_RECORD_COUNT.
	 *
	 * First we compute the index of the last element
	 * which would be fetched from each region,
	 * g0 is in [fri, fri + num - 1], and
	 * g1 is in [0, RAS_MAX_RECORD_COUNT - 1].
	 * Then, if g0 < RAS_MAX_RECORD_COUNT, the index of
	 * the last element to fetch, we set g0 to _the number_
	 * of elements to fetch, @num, since we know that the last
	 * indexed to be fetched does not exceed the table.
	 *
	 * If, however, g0 >= RAS_MAX_RECORD_COUNT, then
	 * we set g0 to the number of elements to read
	 * until the end of the table, and g1 to the number of
	 * elements to read from the beginning of the table.
	 */
	g0 = control->ras_fri + num - 1;
	g1 = g0 % control->ras_max_record_count;
	if (g0 < control->ras_max_record_count) {
		g0 = num;
		g1 = 0;
	} else {
		g0 = control->ras_max_record_count - control->ras_fri;
		g1 += 1;
	}

	mutex_lock(&control->ras_tbl_mutex);
	res = __ras_eeprom_read(control, buf, control->ras_fri, g0);
	if (res)
		goto Out;
	if (g1) {
		res = __ras_eeprom_read(control,
					buf + g0 * RAS_TABLE_RECORD_SIZE, 0, g1);
		if (res)
			goto Out;
	}

	res = 0;

	/* Read up everything? Then transform.
	 */
	pp = buf;
	for (i = 0; i < num; i++, pp += RAS_TABLE_RECORD_SIZE) {
		__decode_table_record_from_buf(control, &record[i], pp);

		/* update bad channel bitmap */
		if ((record[i].mem_channel < BITS_PER_TYPE(control->bad_channel_bitmap)) &&
		    !(control->bad_channel_bitmap & (1 << record[i].mem_channel))) {
			control->bad_channel_bitmap |= 1 << record[i].mem_channel;
			control->update_channel_flag = true;
		}
	}
Out:
	kfree(buf);
	mutex_unlock(&control->ras_tbl_mutex);

	return res;
}

uint32_t ras_eeprom_max_record_count(struct ras_core_context *ras_core)
{
	struct ras_eeprom_control *control = &ras_core->ras_eeprom;

	/* get available eeprom table version first before eeprom table init */
	ras_set_eeprom_table_version(control);

	if (control->tbl_hdr.version >= RAS_TABLE_VER_V2_1)
		return RAS_MAX_RECORD_COUNT_V2_1;
	else
		return RAS_MAX_RECORD_COUNT;
}

/**
 * __verify_ras_table_checksum -- verify the RAS EEPROM table checksum
 * @control: pointer to control structure
 *
 * Check the checksum of the stored in EEPROM RAS table.
 *
 * Return 0 if the checksum is correct,
 * positive if it is not correct, and
 * -errno on I/O error.
 */
static int __verify_ras_table_checksum(struct ras_eeprom_control *control)
{
	struct ras_core_context *ras_core = to_ras_core_context(control);
	int buf_size, res;
	u8  csum, *buf, *pp;

	if (control->tbl_hdr.version >= RAS_TABLE_VER_V2_1)
		buf_size = RAS_TABLE_HEADER_SIZE +
			   RAS_TABLE_V2_1_INFO_SIZE +
			   control->ras_num_recs * RAS_TABLE_RECORD_SIZE;
	else
		buf_size = RAS_TABLE_HEADER_SIZE +
			   control->ras_num_recs * RAS_TABLE_RECORD_SIZE;

	buf = kzalloc(buf_size, GFP_KERNEL);
	if (!buf) {
		RAS_DEV_ERR(ras_core->dev,
			"Out of memory checking RAS table checksum.\n");
		return -ENOMEM;
	}

	res = __eeprom_read(ras_core,
				 control->i2c_address +
				 control->ras_header_offset,
				 buf, buf_size);
	if (res < buf_size) {
		RAS_DEV_ERR(ras_core->dev,
			"Partial read for checksum, res:%d\n", res);
		/* On partial reads, return -EIO.
		 */
		if (res >= 0)
			res = -EIO;
		goto Out;
	}

	csum = 0;
	for (pp = buf; pp < buf + buf_size; pp++)
		csum += *pp;
Out:
	kfree(buf);
	return res < 0 ? res : csum;
}

static int __read_table_ras_info(struct ras_eeprom_control *control)
{
	struct ras_eeprom_table_ras_info *rai = &control->tbl_rai;
	struct ras_core_context *ras_core = to_ras_core_context(control);
	unsigned char *buf;
	int res;

	buf = kzalloc(RAS_TABLE_V2_1_INFO_SIZE, GFP_KERNEL);
	if (!buf) {
		RAS_DEV_ERR(ras_core->dev,
			"Failed to alloc buf to read EEPROM table ras info\n");
		return -ENOMEM;
	}

	/**
	 * EEPROM table V2_1 supports ras info,
	 * read EEPROM table ras info
	 */
	res = __eeprom_read(ras_core,
			      control->i2c_address + control->ras_info_offset,
			      buf, RAS_TABLE_V2_1_INFO_SIZE);
	if (res < RAS_TABLE_V2_1_INFO_SIZE) {
		RAS_DEV_ERR(ras_core->dev,
			"Failed to read EEPROM table ras info, res:%d\n", res);
		res = res >= 0 ? -EIO : res;
		goto Out;
	}

	__decode_table_ras_info_from_buf(rai, buf);

Out:
	kfree(buf);
	return res == RAS_TABLE_V2_1_INFO_SIZE ? 0 : res;
}

static int __check_ras_table_status(struct ras_core_context *ras_core)
{
	struct ras_eeprom_control *control = &ras_core->ras_eeprom;
	unsigned char buf[RAS_TABLE_HEADER_SIZE] = { 0 };
	struct ras_eeprom_table_header *hdr;
	int res;

	hdr = &control->tbl_hdr;

	if (!__is_ras_eeprom_supported(ras_core))
		return 0;

	if (!__get_eeprom_i2c_addr(ras_core, control))
		return -EINVAL;

	control->ras_header_offset = RAS_HDR_START;
	control->ras_info_offset = RAS_TABLE_V2_1_INFO_START;
	mutex_init(&control->ras_tbl_mutex);

	/* Read the table header from EEPROM address */
	res = __eeprom_read(ras_core,
			      control->i2c_address + control->ras_header_offset,
			      buf, RAS_TABLE_HEADER_SIZE);
	if (res < RAS_TABLE_HEADER_SIZE) {
		RAS_DEV_ERR(ras_core->dev,
			"Failed to read EEPROM table header, res:%d\n", res);
		return res >= 0 ? -EIO : res;
	}

	__decode_table_header_from_buf(hdr, buf);

	if (hdr->header != RAS_TABLE_HDR_VAL &&
	    hdr->header != RAS_TABLE_HDR_BAD) {
		RAS_DEV_INFO(ras_core->dev, "Creating a new EEPROM table");
		return ras_eeprom_reset_table(ras_core);
	}

	switch (hdr->version) {
	case RAS_TABLE_VER_V2_1:
	case RAS_TABLE_VER_V3:
		control->ras_num_recs = RAS_NUM_RECS_V2_1(hdr);
		control->ras_record_offset = RAS_RECORD_START_V2_1;
		control->ras_max_record_count = RAS_MAX_RECORD_COUNT_V2_1;
		break;
	case RAS_TABLE_VER_V1:
		control->ras_num_recs = RAS_NUM_RECS(hdr);
		control->ras_record_offset = RAS_RECORD_START;
		control->ras_max_record_count = RAS_MAX_RECORD_COUNT;
		break;
	default:
		RAS_DEV_ERR(ras_core->dev,
			"RAS header invalid, unsupported version: %u",
			hdr->version);
		return -EINVAL;
	}

	if (control->ras_num_recs > control->ras_max_record_count) {
		RAS_DEV_ERR(ras_core->dev,
			"RAS header invalid, records in header: %u max allowed :%u",
			control->ras_num_recs, control->ras_max_record_count);
		return -EINVAL;
	}

	control->ras_fri = RAS_OFFSET_TO_INDEX(control, hdr->first_rec_offset);

	return 0;
}

int ras_eeprom_check_storage_status(struct ras_core_context *ras_core)
{
	struct ras_eeprom_control *control = &ras_core->ras_eeprom;
	struct ras_eeprom_table_header *hdr;
	int bad_page_count;
	int res = 0;

	if (!__is_ras_eeprom_supported(ras_core))
		return 0;

	if (!__get_eeprom_i2c_addr(ras_core, control))
		return -EINVAL;

	hdr = &control->tbl_hdr;

	bad_page_count = ras_umc_get_badpage_count(ras_core);
	if (hdr->header == RAS_TABLE_HDR_VAL) {
		RAS_DEV_INFO(ras_core->dev,
			"Found existing EEPROM table with %d records\n",
			bad_page_count);

		if (hdr->version >= RAS_TABLE_VER_V2_1) {
			res = __read_table_ras_info(control);
			if (res)
				return res;
		}

		res = __verify_ras_table_checksum(control);
		if (res)
			RAS_DEV_ERR(ras_core->dev,
				"RAS table incorrect checksum or error:%d\n", res);

		/* Warn if we are at 90% of the threshold or above
		 */
		if (10 * bad_page_count >= 9 * control->record_threshold_count)
			RAS_DEV_WARN(ras_core->dev,
				"RAS records:%u exceeds 90%% of threshold:%d\n",
				bad_page_count,
				control->record_threshold_count);

	} else if (hdr->header == RAS_TABLE_HDR_BAD &&
		   control->record_threshold_config != 0) {
		if (hdr->version >= RAS_TABLE_VER_V2_1) {
			res = __read_table_ras_info(control);
			if (res)
				return res;
		}

		res = __verify_ras_table_checksum(control);
		if (res)
			RAS_DEV_ERR(ras_core->dev,
				"RAS Table incorrect checksum or error:%d\n", res);

		if (control->record_threshold_count >= bad_page_count) {
			/* This means that, the threshold was increased since
			 * the last time the system was booted, and now,
			 * ras->record_threshold_count - control->num_recs > 0,
			 * so that at least one more record can be saved,
			 * before the page count threshold is reached.
			 */
			RAS_DEV_INFO(ras_core->dev,
				"records:%d threshold:%d, resetting RAS table header signature",
				bad_page_count,
				control->record_threshold_count);
			res = ras_eeprom_correct_header_tag(control, RAS_TABLE_HDR_VAL);
		} else {
			RAS_DEV_ERR(ras_core->dev, "RAS records:%d exceed threshold:%d",
				bad_page_count, control->record_threshold_count);
			if ((control->record_threshold_config == WARN_NONSTOP_OVER_THRESHOLD) ||
				(control->record_threshold_config == NONSTOP_OVER_THRESHOLD)) {
				RAS_DEV_WARN(ras_core->dev,
				"Please consult AMD Service Action Guide (SAG) for appropriate service procedures\n");
				res = 0;
			} else {
				ras_core->is_rma = true;
				RAS_DEV_ERR(ras_core->dev,
				"User defined threshold is set, runtime service will be halt when threshold is reached\n");
			}
		}
	}

	return res < 0 ? res : 0;
}

int ras_eeprom_hw_init(struct ras_core_context *ras_core)
{
	struct ras_eeprom_control *control;
	struct ras_eeprom_config *eeprom_cfg;

	if (!ras_core)
		return -EINVAL;

	ras_core->is_rma = false;

	control = &ras_core->ras_eeprom;

	memset(control, 0, sizeof(*control));

	eeprom_cfg = &ras_core->config->eeprom_cfg;
	control->record_threshold_config =
		eeprom_cfg->eeprom_record_threshold_config;

	control->record_threshold_count = ras_eeprom_max_record_count(ras_core);
	if (eeprom_cfg->eeprom_record_threshold_count <
		control->record_threshold_count)
		control->record_threshold_count =
			eeprom_cfg->eeprom_record_threshold_count;

	control->sys_func = eeprom_cfg->eeprom_sys_fn;
	control->max_read_len = eeprom_cfg->max_i2c_read_len;
	control->max_write_len = eeprom_cfg->max_i2c_write_len;
	control->i2c_adapter = eeprom_cfg->eeprom_i2c_adapter;
	control->i2c_port = eeprom_cfg->eeprom_i2c_port;
	control->i2c_address = eeprom_cfg->eeprom_i2c_addr;

	control->update_channel_flag = false;

	return __check_ras_table_status(ras_core);
}

int ras_eeprom_hw_fini(struct ras_core_context *ras_core)
{
	struct ras_eeprom_control *control;

	if (!ras_core)
		return -EINVAL;

	control = &ras_core->ras_eeprom;
	mutex_destroy(&control->ras_tbl_mutex);

	return 0;
}

uint32_t ras_eeprom_get_record_count(struct ras_core_context *ras_core)
{
	if (!ras_core)
		return 0;

	return ras_core->ras_eeprom.ras_num_recs;
}

void ras_eeprom_sync_info(struct ras_core_context *ras_core)
{
	struct ras_eeprom_control *control;

	if (!ras_core)
		return;

	control = &ras_core->ras_eeprom;
	ras_core_event_notify(ras_core, RAS_EVENT_ID__UPDATE_BAD_PAGE_NUM,
		&control->ras_num_recs);
	ras_core_event_notify(ras_core, RAS_EVENT_ID__UPDATE_BAD_CHANNEL_BITMAP,
		&control->bad_channel_bitmap);
}

enum ras_gpu_health_status
	ras_eeprom_check_gpu_status(struct ras_core_context *ras_core)
{
	struct ras_eeprom_control *control = &ras_core->ras_eeprom;
	struct ras_eeprom_table_ras_info *rai = &control->tbl_rai;

	if (!__is_ras_eeprom_supported(ras_core) ||
	    !control->record_threshold_config)
		return RAS_GPU_HEALTH_NONE;

	if (control->tbl_hdr.header == RAS_TABLE_HDR_BAD)
		return RAS_GPU_IN_BAD_STATUS;

	return rai->rma_status;
}