// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * FRU (Field-Replaceable Unit) Memory Poison Manager
 *
 * Copyright (c) 2024, Advanced Micro Devices, Inc.
 * All Rights Reserved.
 *
 * Authors:
 *	Naveen Krishna Chatradhi <naveenkrishna.chatradhi@amd.com>
 *	Muralidhara M K <muralidhara.mk@amd.com>
 *	Yazen Ghannam <Yazen.Ghannam@amd.com>
 *
 * Implementation notes, assumptions, and limitations:
 *
 * - FRU memory poison section and memory poison descriptor definitions are not yet
 *   included in the UEFI specification. So they are defined here. Afterwards, they
 *   may be moved to linux/cper.h, if appropriate.
 *
 * - Platforms based on AMD MI300 systems will be the first to use these structures.
 *   There are a number of assumptions made here that will need to be generalized
 *   to support other platforms.
 *
 *   AMD MI300-based platform(s) assumptions:
 *   - Memory errors are reported through x86 MCA.
 *   - The entire DRAM row containing a memory error should be retired.
 *   - There will be (1) FRU memory poison section per CPER.
 *   - The FRU will be the CPU package (processor socket).
 *   - The default number of memory poison descriptor entries should be (8).
 *   - The platform will use ACPI ERST for persistent storage.
 *   - All FRU records should be saved to persistent storage. Module init will
 *     fail if any FRU record is not successfully written.
 *
 * - Boot time memory retirement may occur later than ideal due to dependencies
 *   on other libraries and drivers. This leaves a gap where bad memory may be
 *   accessed during early boot stages.
 *
 * - Enough memory should be pre-allocated for each FRU record to be able to hold
 *   the expected number of descriptor entries. This, mostly empty, record is
 *   written to storage during init time. Subsequent writes to the same record
 *   should allow the Platform to update the stored record in-place. Otherwise,
 *   if the record is extended, then the Platform may need to perform costly memory
 *   management operations on the storage. For example, the Platform may spend time
 *   in Firmware copying and invalidating memory on a relatively slow SPI ROM.
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/cper.h>
#include <linux/ras.h>
#include <linux/cpu.h>

#include <acpi/apei.h>

#include <asm/cpu_device_id.h>
#include <asm/mce.h>

#include "../debugfs.h"

#include "atl/internal.h"

#define INVALID_CPU			UINT_MAX

/* Validation Bits */
#define FMP_VALID_ARCH_TYPE		BIT_ULL(0)
#define FMP_VALID_ARCH			BIT_ULL(1)
#define FMP_VALID_ID_TYPE		BIT_ULL(2)
#define FMP_VALID_ID			BIT_ULL(3)
#define FMP_VALID_LIST_ENTRIES		BIT_ULL(4)
#define FMP_VALID_LIST			BIT_ULL(5)

/* FRU Architecture Types */
#define FMP_ARCH_TYPE_X86_CPUID_1_EAX	0

/* FRU ID Types */
#define FMP_ID_TYPE_X86_PPIN		0

/* FRU Memory Poison Section */
struct cper_sec_fru_mem_poison {
	u32 checksum;
	u64 validation_bits;
	u32 fru_arch_type;
	u64 fru_arch;
	u32 fru_id_type;
	u64 fru_id;
	u32 nr_entries;
} __packed;

/* FRU Descriptor ID Types */
#define FPD_HW_ID_TYPE_MCA_IPID		0

/* FRU Descriptor Address Types */
#define FPD_ADDR_TYPE_MCA_ADDR		0

/* Memory Poison Descriptor */
struct cper_fru_poison_desc {
	u64 timestamp;
	u32 hw_id_type;
	u64 hw_id;
	u32 addr_type;
	u64 addr;
} __packed;

/* Collection of headers and sections for easy pointer use. */
struct fru_rec {
	struct cper_record_header	hdr;
	struct cper_section_descriptor	sec_desc;
	struct cper_sec_fru_mem_poison	fmp;
	struct cper_fru_poison_desc	entries[];
} __packed;

/*
 * Pointers to the complete CPER record of each FRU.
 *
 * Memory allocation will include padded space for descriptor entries.
 */
static struct fru_rec **fru_records;

/* system physical addresses array */
static u64 *spa_entries;

static struct dentry *fmpm_dfs_dir;
static struct dentry *fmpm_dfs_entries;

#define CPER_CREATOR_FMP						\
	GUID_INIT(0xcd5c2993, 0xf4b2, 0x41b2, 0xb5, 0xd4, 0xf9, 0xc3,	\
		  0xa0, 0x33, 0x08, 0x75)

#define CPER_SECTION_TYPE_FMP						\
	GUID_INIT(0x5e4706c1, 0x5356, 0x48c6, 0x93, 0x0b, 0x52, 0xf2,	\
		  0x12, 0x0a, 0x44, 0x58)

/**
 * DOC: max_nr_entries (byte)
 * Maximum number of descriptor entries possible for each FRU.
 *
 * Values between '1' and '255' are valid.
 * No input or '0' will default to FMPM_DEFAULT_MAX_NR_ENTRIES.
 */
static u8 max_nr_entries;
module_param(max_nr_entries, byte, 0644);
MODULE_PARM_DESC(max_nr_entries,
		 "Maximum number of memory poison descriptor entries per FRU");

#define FMPM_DEFAULT_MAX_NR_ENTRIES	8

/* Maximum number of FRUs in the system. */
#define FMPM_MAX_NR_FRU			256
static unsigned int max_nr_fru;

/* Total length of record including headers and list of descriptor entries. */
static size_t max_rec_len;

#define FMPM_MAX_REC_LEN (sizeof(struct fru_rec) + (sizeof(struct cper_fru_poison_desc) * 255))

/* Total number of SPA entries across all FRUs. */
static unsigned int spa_nr_entries;

/*
 * Protect the local records cache in fru_records and prevent concurrent
 * writes to storage. This is only needed after init once notifier block
 * registration is done.
 *
 * The majority of a record is fixed at module init and will not change
 * during run time. The entries within a record will be updated as new
 * errors are reported. The mutex should be held whenever the entries are
 * accessed during run time.
 */
static DEFINE_MUTEX(fmpm_update_mutex);

#define for_each_fru(i, rec) \
	for (i = 0; rec = fru_records[i], i < max_nr_fru; i++)

static inline u32 get_fmp_len(struct fru_rec *rec)
{
	return rec->sec_desc.section_length - sizeof(struct cper_section_descriptor);
}

static struct fru_rec *get_fru_record(u64 fru_id)
{
	struct fru_rec *rec;
	unsigned int i;

	for_each_fru(i, rec) {
		if (rec->fmp.fru_id == fru_id)
			return rec;
	}

	pr_debug("Record not found for FRU 0x%016llx\n", fru_id);

	return NULL;
}

/*
 * Sum up all bytes within the FRU Memory Poison Section including the Memory
 * Poison Descriptor entries.
 *
 * Don't include the old checksum here. It's a u32 value, so summing each of its
 * bytes will give the wrong total.
 */
static u32 do_fmp_checksum(struct cper_sec_fru_mem_poison *fmp, u32 len)
{
	u32 checksum = 0;
	u8 *buf, *end;

	/* Skip old checksum. */
	buf = (u8 *)fmp + sizeof(u32);
	end = buf + len;

	while (buf < end)
		checksum += (u8)(*(buf++));

	return checksum;
}

static int update_record_on_storage(struct fru_rec *rec)
{
	u32 len, checksum;
	int ret;

	/* Calculate a new checksum. */
	len = get_fmp_len(rec);

	/* Get the current total. */
	checksum = do_fmp_checksum(&rec->fmp, len);

	/* Use the complement value. */
	rec->fmp.checksum = -checksum;

	pr_debug("Writing to storage\n");

	ret = erst_write(&rec->hdr);
	if (ret) {
		pr_warn("Storage update failed for FRU 0x%016llx\n", rec->fmp.fru_id);

		if (ret == -ENOSPC)
			pr_warn("Not enough space on storage\n");
	}

	return ret;
}

static bool rec_has_valid_entries(struct fru_rec *rec)
{
	if (!(rec->fmp.validation_bits & FMP_VALID_LIST_ENTRIES))
		return false;

	if (!(rec->fmp.validation_bits & FMP_VALID_LIST))
		return false;

	return true;
}

/*
 * Row retirement is done on MI300 systems, and some bits are 'don't
 * care' for comparing addresses with unique physical rows.  This
 * includes all column bits and the row[13] bit.
 */
#define MASK_ADDR(addr)	((addr) & ~(MI300_UMC_MCA_ROW13 | MI300_UMC_MCA_COL))

static bool fpds_equal(struct cper_fru_poison_desc *old, struct cper_fru_poison_desc *new)
{
	/*
	 * Ignore timestamp field.
	 * The same physical error may be reported multiple times due to stuck bits, etc.
	 *
	 * Also, order the checks from most->least likely to fail to shortcut the code.
	 */
	if (MASK_ADDR(old->addr) != MASK_ADDR(new->addr))
		return false;

	if (old->hw_id != new->hw_id)
		return false;

	if (old->addr_type != new->addr_type)
		return false;

	if (old->hw_id_type != new->hw_id_type)
		return false;

	return true;
}

static bool rec_has_fpd(struct fru_rec *rec, struct cper_fru_poison_desc *fpd)
{
	unsigned int i;

	for (i = 0; i < rec->fmp.nr_entries; i++) {
		struct cper_fru_poison_desc *fpd_i = &rec->entries[i];

		if (fpds_equal(fpd_i, fpd)) {
			pr_debug("Found duplicate record\n");
			return true;
		}
	}

	return false;
}

static void save_spa(struct fru_rec *rec, unsigned int entry,
		     u64 addr, u64 id, unsigned int cpu)
{
	unsigned int i, fru_idx, spa_entry;
	struct atl_err a_err;
	unsigned long spa;

	if (entry >= max_nr_entries) {
		pr_warn_once("FRU descriptor entry %d out-of-bounds (max: %d)\n",
			     entry, max_nr_entries);
		return;
	}

	/* spa_nr_entries is always multiple of max_nr_entries */
	for (i = 0; i < spa_nr_entries; i += max_nr_entries) {
		fru_idx = i / max_nr_entries;
		if (fru_records[fru_idx] == rec)
			break;
	}

	if (i >= spa_nr_entries) {
		pr_warn_once("FRU record %d not found\n", i);
		return;
	}

	spa_entry = i + entry;
	if (spa_entry >= spa_nr_entries) {
		pr_warn_once("spa_entries[] index out-of-bounds\n");
		return;
	}

	memset(&a_err, 0, sizeof(struct atl_err));

	a_err.addr = addr;
	a_err.ipid = id;
	a_err.cpu  = cpu;

	spa = amd_convert_umc_mca_addr_to_sys_addr(&a_err);
	if (IS_ERR_VALUE(spa)) {
		pr_debug("Failed to get system address\n");
		return;
	}

	spa_entries[spa_entry] = spa;
	pr_debug("fru_idx: %u, entry: %u, spa_entry: %u, spa: 0x%016llx\n",
		 fru_idx, entry, spa_entry, spa_entries[spa_entry]);
}

static void update_fru_record(struct fru_rec *rec, struct mce *m)
{
	struct cper_sec_fru_mem_poison *fmp = &rec->fmp;
	struct cper_fru_poison_desc fpd, *fpd_dest;
	u32 entry = 0;

	mutex_lock(&fmpm_update_mutex);

	memset(&fpd, 0, sizeof(struct cper_fru_poison_desc));

	fpd.timestamp	= m->time;
	fpd.hw_id_type = FPD_HW_ID_TYPE_MCA_IPID;
	fpd.hw_id	= m->ipid;
	fpd.addr_type	= FPD_ADDR_TYPE_MCA_ADDR;
	fpd.addr	= m->addr;

	/* This is the first entry, so just save it. */
	if (!rec_has_valid_entries(rec))
		goto save_fpd;

	/* Ignore already recorded errors. */
	if (rec_has_fpd(rec, &fpd))
		goto out_unlock;

	if (rec->fmp.nr_entries >= max_nr_entries) {
		pr_warn("Exceeded number of entries for FRU 0x%016llx\n", rec->fmp.fru_id);
		goto out_unlock;
	}

	entry  = fmp->nr_entries;

save_fpd:
	save_spa(rec, entry, m->addr, m->ipid, m->extcpu);
	fpd_dest  = &rec->entries[entry];
	memcpy(fpd_dest, &fpd, sizeof(struct cper_fru_poison_desc));

	fmp->nr_entries		 = entry + 1;
	fmp->validation_bits	|= FMP_VALID_LIST_ENTRIES;
	fmp->validation_bits	|= FMP_VALID_LIST;

	pr_debug("Updated FRU 0x%016llx entry #%u\n", fmp->fru_id, entry);

	update_record_on_storage(rec);

out_unlock:
	mutex_unlock(&fmpm_update_mutex);
}

static void retire_dram_row(u64 addr, u64 id, u32 cpu)
{
	struct atl_err a_err;

	memset(&a_err, 0, sizeof(struct atl_err));

	a_err.addr = addr;
	a_err.ipid = id;
	a_err.cpu  = cpu;

	amd_retire_dram_row(&a_err);
}

static int fru_handle_mem_poison(struct notifier_block *nb, unsigned long val, void *data)
{
	struct mce *m = (struct mce *)data;
	struct fru_rec *rec;

	if (!mce_is_memory_error(m))
		return NOTIFY_DONE;

	retire_dram_row(m->addr, m->ipid, m->extcpu);

	/*
	 * An invalid FRU ID should not happen on real errors. But it
	 * could happen from software error injection, etc.
	 */
	rec = get_fru_record(m->ppin);
	if (!rec)
		return NOTIFY_DONE;

	update_fru_record(rec, m);

	return NOTIFY_OK;
}

static struct notifier_block fru_mem_poison_nb = {
	.notifier_call  = fru_handle_mem_poison,
	.priority	= MCE_PRIO_LOWEST,
};

static void retire_mem_fmp(struct fru_rec *rec)
{
	struct cper_sec_fru_mem_poison *fmp = &rec->fmp;
	unsigned int i, cpu;

	for (i = 0; i < fmp->nr_entries; i++) {
		struct cper_fru_poison_desc *fpd = &rec->entries[i];
		unsigned int err_cpu = INVALID_CPU;

		if (fpd->hw_id_type != FPD_HW_ID_TYPE_MCA_IPID)
			continue;

		if (fpd->addr_type != FPD_ADDR_TYPE_MCA_ADDR)
			continue;

		cpus_read_lock();
		for_each_online_cpu(cpu) {
			if (topology_ppin(cpu) == fmp->fru_id) {
				err_cpu = cpu;
				break;
			}
		}
		cpus_read_unlock();

		if (err_cpu == INVALID_CPU)
			continue;

		retire_dram_row(fpd->addr, fpd->hw_id, err_cpu);
		save_spa(rec, i, fpd->addr, fpd->hw_id, err_cpu);
	}
}

static void retire_mem_records(void)
{
	struct fru_rec *rec;
	unsigned int i;

	for_each_fru(i, rec) {
		if (!rec_has_valid_entries(rec))
			continue;

		retire_mem_fmp(rec);
	}
}

/* Set the CPER Record Header and CPER Section Descriptor fields. */
static void set_rec_fields(struct fru_rec *rec)
{
	struct cper_section_descriptor	*sec_desc = &rec->sec_desc;
	struct cper_record_header	*hdr	  = &rec->hdr;

	/*
	 * This is a saved record created with fewer max_nr_entries.
	 * Update the record lengths and keep everything else as-is.
	 */
	if (hdr->record_length && hdr->record_length < max_rec_len) {
		pr_debug("Growing record 0x%016llx from %u to %zu bytes\n",
			 hdr->record_id, hdr->record_length, max_rec_len);
		goto update_lengths;
	}

	memcpy(hdr->signature, CPER_SIG_RECORD, CPER_SIG_SIZE);
	hdr->revision			= CPER_RECORD_REV;
	hdr->signature_end		= CPER_SIG_END;

	/*
	 * Currently, it is assumed that there is one FRU Memory Poison
	 * section per CPER. But this may change for other implementations.
	 */
	hdr->section_count		= 1;

	/* The logged errors are recoverable. Otherwise, they'd never make it here. */
	hdr->error_severity		= CPER_SEV_RECOVERABLE;

	hdr->validation_bits		= 0;
	hdr->creator_id			= CPER_CREATOR_FMP;
	hdr->notification_type		= CPER_NOTIFY_MCE;
	hdr->record_id			= cper_next_record_id();
	hdr->flags			= CPER_HW_ERROR_FLAGS_PREVERR;

	sec_desc->section_offset	= sizeof(struct cper_record_header);
	sec_desc->revision		= CPER_SEC_REV;
	sec_desc->validation_bits	= 0;
	sec_desc->flags			= CPER_SEC_PRIMARY;
	sec_desc->section_type		= CPER_SECTION_TYPE_FMP;
	sec_desc->section_severity	= CPER_SEV_RECOVERABLE;

update_lengths:
	hdr->record_length		= max_rec_len;
	sec_desc->section_length	= max_rec_len - sizeof(struct cper_record_header);
}

static int save_new_records(void)
{
	DECLARE_BITMAP(new_records, FMPM_MAX_NR_FRU);
	struct fru_rec *rec;
	unsigned int i;
	int ret = 0;

	for_each_fru(i, rec) {
		/* No need to update saved records that match the current record size. */
		if (rec->hdr.record_length == max_rec_len)
			continue;

		if (!rec->hdr.record_length)
			set_bit(i, new_records);

		set_rec_fields(rec);

		ret = update_record_on_storage(rec);
		if (ret)
			goto out_clear;
	}

	return ret;

out_clear:
	for_each_fru(i, rec) {
		if (!test_bit(i, new_records))
			continue;

		erst_clear(rec->hdr.record_id);
	}

	return ret;
}

/* Check that the record matches expected types for the current system.*/
static bool fmp_is_usable(struct fru_rec *rec)
{
	struct cper_sec_fru_mem_poison *fmp = &rec->fmp;
	u64 cpuid;

	pr_debug("Validation bits: 0x%016llx\n", fmp->validation_bits);

	if (!(fmp->validation_bits & FMP_VALID_ARCH_TYPE)) {
		pr_debug("Arch type unknown\n");
		return false;
	}

	if (fmp->fru_arch_type != FMP_ARCH_TYPE_X86_CPUID_1_EAX) {
		pr_debug("Arch type not 'x86 Family/Model/Stepping'\n");
		return false;
	}

	if (!(fmp->validation_bits & FMP_VALID_ARCH)) {
		pr_debug("Arch value unknown\n");
		return false;
	}

	cpuid = cpuid_eax(1);
	if (fmp->fru_arch != cpuid) {
		pr_debug("Arch value mismatch: record = 0x%016llx, system = 0x%016llx\n",
			 fmp->fru_arch, cpuid);
		return false;
	}

	if (!(fmp->validation_bits & FMP_VALID_ID_TYPE)) {
		pr_debug("FRU ID type unknown\n");
		return false;
	}

	if (fmp->fru_id_type != FMP_ID_TYPE_X86_PPIN) {
		pr_debug("FRU ID type is not 'x86 PPIN'\n");
		return false;
	}

	if (!(fmp->validation_bits & FMP_VALID_ID)) {
		pr_debug("FRU ID value unknown\n");
		return false;
	}

	return true;
}

static bool fmp_is_valid(struct fru_rec *rec)
{
	struct cper_sec_fru_mem_poison *fmp = &rec->fmp;
	u32 checksum, len;

	len = get_fmp_len(rec);
	if (len < sizeof(struct cper_sec_fru_mem_poison)) {
		pr_debug("fmp length is too small\n");
		return false;
	}

	/* Checksum must sum to zero for the entire section. */
	checksum = do_fmp_checksum(fmp, len) + fmp->checksum;
	if (checksum) {
		pr_debug("fmp checksum failed: sum = 0x%x\n", checksum);
		print_hex_dump_debug("fmp record: ", DUMP_PREFIX_NONE, 16, 1, fmp, len, false);
		return false;
	}

	if (!fmp_is_usable(rec))
		return false;

	return true;
}

static struct fru_rec *get_valid_record(struct fru_rec *old)
{
	struct fru_rec *new;

	if (!fmp_is_valid(old)) {
		pr_debug("Ignoring invalid record\n");
		return NULL;
	}

	new = get_fru_record(old->fmp.fru_id);
	if (!new)
		pr_debug("Ignoring record for absent FRU\n");

	return new;
}

/*
 * Fetch saved records from persistent storage.
 *
 * For each found record:
 * - If it was not created by this module, then ignore it.
 * - If it is valid, then copy its data to the local cache.
 * - If it is not valid, then erase it.
 */
static int get_saved_records(void)
{
	struct fru_rec *old, *new;
	u64 record_id;
	int ret, pos;
	ssize_t len;

	old = kmalloc(FMPM_MAX_REC_LEN, GFP_KERNEL);
	if (!old) {
		ret = -ENOMEM;
		goto out;
	}

	ret = erst_get_record_id_begin(&pos);
	if (ret < 0)
		goto out_end;

	while (!erst_get_record_id_next(&pos, &record_id)) {
		if (record_id == APEI_ERST_INVALID_RECORD_ID)
			goto out_end;
		/*
		 * Make sure to clear temporary buffer between reads to avoid
		 * leftover data from records of various sizes.
		 */
		memset(old, 0, FMPM_MAX_REC_LEN);

		len = erst_read_record(record_id, &old->hdr, FMPM_MAX_REC_LEN,
				       sizeof(struct fru_rec), &CPER_CREATOR_FMP);
		if (len < 0)
			continue;

		new = get_valid_record(old);
		if (!new) {
			erst_clear(record_id);
			continue;
		}

		if (len > max_rec_len) {
			unsigned int saved_nr_entries;

			saved_nr_entries  = len - sizeof(struct fru_rec);
			saved_nr_entries /= sizeof(struct cper_fru_poison_desc);

			pr_warn("Saved record found with %u entries.\n", saved_nr_entries);
			pr_warn("Please increase max_nr_entries to %u.\n", saved_nr_entries);

			ret = -EINVAL;
			goto out_end;
		}

		/* Restore the record */
		memcpy(new, old, len);
	}

out_end:
	erst_get_record_id_end();
	kfree(old);
out:
	return ret;
}

static void set_fmp_fields(struct fru_rec *rec, unsigned int cpu)
{
	struct cper_sec_fru_mem_poison *fmp = &rec->fmp;

	fmp->fru_arch_type    = FMP_ARCH_TYPE_X86_CPUID_1_EAX;
	fmp->validation_bits |= FMP_VALID_ARCH_TYPE;

	/* Assume all CPUs in the system have the same value for now. */
	fmp->fru_arch	      = cpuid_eax(1);
	fmp->validation_bits |= FMP_VALID_ARCH;

	fmp->fru_id_type      = FMP_ID_TYPE_X86_PPIN;
	fmp->validation_bits |= FMP_VALID_ID_TYPE;

	fmp->fru_id	      = topology_ppin(cpu);
	fmp->validation_bits |= FMP_VALID_ID;
}

static int init_fmps(void)
{
	struct fru_rec *rec;
	unsigned int i, cpu;
	int ret = 0;

	for_each_fru(i, rec) {
		unsigned int fru_cpu = INVALID_CPU;

		cpus_read_lock();
		for_each_online_cpu(cpu) {
			if (topology_physical_package_id(cpu) == i) {
				fru_cpu = cpu;
				break;
			}
		}
		cpus_read_unlock();

		if (fru_cpu == INVALID_CPU) {
			pr_debug("Failed to find matching CPU for FRU #%u\n", i);
			ret = -ENODEV;
			break;
		}

		set_fmp_fields(rec, fru_cpu);
	}

	return ret;
}

static int get_system_info(void)
{
	/* Only load on MI300A systems for now. */
	if (!(boot_cpu_data.x86_model >= 0x90 &&
	      boot_cpu_data.x86_model <= 0x9f))
		return -ENODEV;

	if (!cpu_feature_enabled(X86_FEATURE_AMD_PPIN)) {
		pr_debug("PPIN feature not available\n");
		return -ENODEV;
	}

	/* Use CPU socket as FRU for MI300 systems. */
	max_nr_fru = topology_max_packages();
	if (!max_nr_fru)
		return -ENODEV;

	if (max_nr_fru > FMPM_MAX_NR_FRU) {
		pr_warn("Too many FRUs to manage: found: %u, max: %u\n",
			max_nr_fru, FMPM_MAX_NR_FRU);
		return -ENODEV;
	}

	if (!max_nr_entries)
		max_nr_entries = FMPM_DEFAULT_MAX_NR_ENTRIES;

	spa_nr_entries = max_nr_fru * max_nr_entries;

	max_rec_len  = sizeof(struct fru_rec);
	max_rec_len += sizeof(struct cper_fru_poison_desc) * max_nr_entries;

	pr_info("max FRUs: %u, max entries: %u, max record length: %lu\n",
		 max_nr_fru, max_nr_entries, max_rec_len);

	return 0;
}

static void free_records(void)
{
	struct fru_rec *rec;
	int i;

	for_each_fru(i, rec)
		kfree(rec);

	kfree(fru_records);
	kfree(spa_entries);
}

static int allocate_records(void)
{
	int i, ret = 0;

	fru_records = kcalloc(max_nr_fru, sizeof(struct fru_rec *), GFP_KERNEL);
	if (!fru_records) {
		ret = -ENOMEM;
		goto out;
	}

	for (i = 0; i < max_nr_fru; i++) {
		fru_records[i] = kzalloc(max_rec_len, GFP_KERNEL);
		if (!fru_records[i]) {
			ret = -ENOMEM;
			goto out_free;
		}
	}

	spa_entries = kcalloc(spa_nr_entries, sizeof(u64), GFP_KERNEL);
	if (!spa_entries) {
		ret = -ENOMEM;
		goto out_free;
	}

	for (i = 0; i < spa_nr_entries; i++)
		spa_entries[i] = INVALID_SPA;

	return ret;

out_free:
	while (--i >= 0)
		kfree(fru_records[i]);

	kfree(fru_records);
out:
	return ret;
}

static void *fmpm_start(struct seq_file *f, loff_t *pos)
{
	if (*pos >= (spa_nr_entries + 1))
		return NULL;
	return pos;
}

static void *fmpm_next(struct seq_file *f, void *data, loff_t *pos)
{
	if (++(*pos) >= (spa_nr_entries + 1))
		return NULL;
	return pos;
}

static void fmpm_stop(struct seq_file *f, void *data)
{
}

#define SHORT_WIDTH	8
#define U64_WIDTH	18
#define TIMESTAMP_WIDTH	19
#define LONG_WIDTH	24
#define U64_PAD		(LONG_WIDTH - U64_WIDTH)
#define TS_PAD		(LONG_WIDTH - TIMESTAMP_WIDTH)
static int fmpm_show(struct seq_file *f, void *data)
{
	unsigned int fru_idx, entry, spa_entry, line;
	struct cper_fru_poison_desc *fpd;
	struct fru_rec *rec;

	line = *(loff_t *)data;
	if (line == 0) {
		seq_printf(f, "%-*s", SHORT_WIDTH, "fru_idx");
		seq_printf(f, "%-*s", LONG_WIDTH,  "fru_id");
		seq_printf(f, "%-*s", SHORT_WIDTH, "entry");
		seq_printf(f, "%-*s", LONG_WIDTH,  "timestamp");
		seq_printf(f, "%-*s", LONG_WIDTH,  "hw_id");
		seq_printf(f, "%-*s", LONG_WIDTH,  "addr");
		seq_printf(f, "%-*s", LONG_WIDTH,  "spa");
		goto out_newline;
	}

	spa_entry = line - 1;
	fru_idx	  = spa_entry / max_nr_entries;
	entry	  = spa_entry % max_nr_entries;

	rec = fru_records[fru_idx];
	if (!rec)
		goto out;

	seq_printf(f, "%-*u",		SHORT_WIDTH, fru_idx);
	seq_printf(f, "0x%016llx%-*s",	rec->fmp.fru_id, U64_PAD, "");
	seq_printf(f, "%-*u",		SHORT_WIDTH, entry);

	mutex_lock(&fmpm_update_mutex);

	if (entry >= rec->fmp.nr_entries) {
		seq_printf(f, "%-*s", LONG_WIDTH, "*");
		seq_printf(f, "%-*s", LONG_WIDTH, "*");
		seq_printf(f, "%-*s", LONG_WIDTH, "*");
		seq_printf(f, "%-*s", LONG_WIDTH, "*");
		goto out_unlock;
	}

	fpd = &rec->entries[entry];

	seq_printf(f, "%ptT%-*s",	&fpd->timestamp, TS_PAD,  "");
	seq_printf(f, "0x%016llx%-*s",	fpd->hw_id,	 U64_PAD, "");
	seq_printf(f, "0x%016llx%-*s",	fpd->addr,	 U64_PAD, "");

	if (spa_entries[spa_entry] == INVALID_SPA)
		seq_printf(f, "%-*s", LONG_WIDTH, "*");
	else
		seq_printf(f, "0x%016llx%-*s", spa_entries[spa_entry], U64_PAD, "");

out_unlock:
	mutex_unlock(&fmpm_update_mutex);
out_newline:
	seq_putc(f, '\n');
out:
	return 0;
}

static const struct seq_operations fmpm_seq_ops = {
	.start	= fmpm_start,
	.next	= fmpm_next,
	.stop	= fmpm_stop,
	.show	= fmpm_show,
};

static int fmpm_open(struct inode *inode, struct file *file)
{
	return seq_open(file, &fmpm_seq_ops);
}

static const struct file_operations fmpm_fops = {
	.open		= fmpm_open,
	.release	= seq_release,
	.read		= seq_read,
	.llseek		= seq_lseek,
};

static void setup_debugfs(void)
{
	struct dentry *dfs = ras_get_debugfs_root();

	if (!dfs)
		return;

	fmpm_dfs_dir = debugfs_create_dir("fmpm", dfs);
	if (!fmpm_dfs_dir)
		return;

	fmpm_dfs_entries = debugfs_create_file("entries", 0400, fmpm_dfs_dir, NULL, &fmpm_fops);
	if (!fmpm_dfs_entries)
		debugfs_remove(fmpm_dfs_dir);
}

static const struct x86_cpu_id fmpm_cpuids[] = {
	X86_MATCH_VENDOR_FAM(AMD, 0x19, NULL),
	{ }
};
MODULE_DEVICE_TABLE(x86cpu, fmpm_cpuids);

static int __init fru_mem_poison_init(void)
{
	int ret;

	if (!x86_match_cpu(fmpm_cpuids)) {
		ret = -ENODEV;
		goto out;
	}

	if (erst_disable) {
		pr_debug("ERST not available\n");
		ret = -ENODEV;
		goto out;
	}

	ret = get_system_info();
	if (ret)
		goto out;

	ret = allocate_records();
	if (ret)
		goto out;

	ret = init_fmps();
	if (ret)
		goto out_free;

	ret = get_saved_records();
	if (ret)
		goto out_free;

	ret = save_new_records();
	if (ret)
		goto out_free;

	setup_debugfs();

	retire_mem_records();

	mce_register_decode_chain(&fru_mem_poison_nb);

	pr_info("FRU Memory Poison Manager initialized\n");
	return 0;

out_free:
	free_records();
out:
	return ret;
}

static void __exit fru_mem_poison_exit(void)
{
	mce_unregister_decode_chain(&fru_mem_poison_nb);
	debugfs_remove(fmpm_dfs_dir);
	free_records();
}

module_init(fru_mem_poison_init);
module_exit(fru_mem_poison_exit);

MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("FRU Memory Poison Manager");