--- /dev/null
+/*
+ * APEI Error Record Serialization Table support
+ *
+ * ERST is a way provided by APEI to save and retrieve hardware error
+ * infomation to and from a persistent store.
+ *
+ * For more information about ERST, please refer to ACPI Specification
+ * version 4.0, section 17.4.
+ *
+ * Copyright 2010 Intel Corp.
+ *   Author: Huang Ying <ying.huang@intel.com>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License version
+ * 2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/delay.h>
+#include <linux/io.h>
+#include <linux/acpi.h>
+#include <linux/uaccess.h>
+#include <linux/cper.h>
+#include <linux/nmi.h>
+#include <acpi/apei.h>
+
+#include "apei-internal.h"
+
+#define ERST_PFX "ERST: "
+
+/* ERST command status */
+#define ERST_STATUS_SUCCESS                    0x0
+#define ERST_STATUS_NOT_ENOUGH_SPACE           0x1
+#define ERST_STATUS_HARDWARE_NOT_AVAILABLE     0x2
+#define ERST_STATUS_FAILED                     0x3
+#define ERST_STATUS_RECORD_STORE_EMPTY         0x4
+#define ERST_STATUS_RECORD_NOT_FOUND           0x5
+
+#define ERST_TAB_ENTRY(tab)                                            \
+       ((struct acpi_whea_header *)((char *)(tab) +                    \
+                                    sizeof(struct acpi_table_erst)))
+
+#define SPIN_UNIT              100                     /* 100ns */
+/* Firmware should respond within 1 miliseconds */
+#define FIRMWARE_TIMEOUT       (1 * NSEC_PER_MSEC)
+#define FIRMWARE_MAX_STALL     50                      /* 50us */
+
+int erst_disable;
+EXPORT_SYMBOL_GPL(erst_disable);
+
+static struct acpi_table_erst *erst_tab;
+
+/* ERST Error Log Address Range atrributes */
+#define ERST_RANGE_RESERVED    0x0001
+#define ERST_RANGE_NVRAM       0x0002
+#define ERST_RANGE_SLOW                0x0004
+
+/*
+ * ERST Error Log Address Range, used as buffer for reading/writing
+ * error records.
+ */
+static struct erst_erange {
+       u64 base;
+       u64 size;
+       void __iomem *vaddr;
+       u32 attr;
+} erst_erange;
+
+/*
+ * Prevent ERST interpreter to run simultaneously, because the
+ * corresponding firmware implementation may not work properly when
+ * invoked simultaneously.
+ *
+ * It is used to provide exclusive accessing for ERST Error Log
+ * Address Range too.
+ */
+static DEFINE_SPINLOCK(erst_lock);
+
+static inline int erst_errno(int command_status)
+{
+       switch (command_status) {
+       case ERST_STATUS_SUCCESS:
+               return 0;
+       case ERST_STATUS_HARDWARE_NOT_AVAILABLE:
+               return -ENODEV;
+       case ERST_STATUS_NOT_ENOUGH_SPACE:
+               return -ENOSPC;
+       case ERST_STATUS_RECORD_STORE_EMPTY:
+       case ERST_STATUS_RECORD_NOT_FOUND:
+               return -ENOENT;
+       default:
+               return -EINVAL;
+       }
+}
+
+static int erst_timedout(u64 *t, u64 spin_unit)
+{
+       if ((s64)*t < spin_unit) {
+               pr_warning(FW_WARN ERST_PFX
+                          "Firmware does not respond in time\n");
+               return 1;
+       }
+       *t -= spin_unit;
+       ndelay(spin_unit);
+       touch_nmi_watchdog();
+       return 0;
+}
+
+static int erst_exec_load_var1(struct apei_exec_context *ctx,
+                              struct acpi_whea_header *entry)
+{
+       return __apei_exec_read_register(entry, &ctx->var1);
+}
+
+static int erst_exec_load_var2(struct apei_exec_context *ctx,
+                              struct acpi_whea_header *entry)
+{
+       return __apei_exec_read_register(entry, &ctx->var2);
+}
+
+static int erst_exec_store_var1(struct apei_exec_context *ctx,
+                               struct acpi_whea_header *entry)
+{
+       return __apei_exec_write_register(entry, ctx->var1);
+}
+
+static int erst_exec_add(struct apei_exec_context *ctx,
+                        struct acpi_whea_header *entry)
+{
+       ctx->var1 += ctx->var2;
+       return 0;
+}
+
+static int erst_exec_subtract(struct apei_exec_context *ctx,
+                             struct acpi_whea_header *entry)
+{
+       ctx->var1 -= ctx->var2;
+       return 0;
+}
+
+static int erst_exec_add_value(struct apei_exec_context *ctx,
+                              struct acpi_whea_header *entry)
+{
+       int rc;
+       u64 val;
+
+       rc = __apei_exec_read_register(entry, &val);
+       if (rc)
+               return rc;
+       val += ctx->value;
+       rc = __apei_exec_write_register(entry, val);
+       return rc;
+}
+
+static int erst_exec_subtract_value(struct apei_exec_context *ctx,
+                                   struct acpi_whea_header *entry)
+{
+       int rc;
+       u64 val;
+
+       rc = __apei_exec_read_register(entry, &val);
+       if (rc)
+               return rc;
+       val -= ctx->value;
+       rc = __apei_exec_write_register(entry, val);
+       return rc;
+}
+
+static int erst_exec_stall(struct apei_exec_context *ctx,
+                          struct acpi_whea_header *entry)
+{
+       u64 stall_time;
+
+       if (ctx->value > FIRMWARE_MAX_STALL) {
+               if (!in_nmi())
+                       pr_warning(FW_WARN ERST_PFX
+                       "Too long stall time for stall instruction: %llx.\n",
+                                  ctx->value);
+               stall_time = FIRMWARE_MAX_STALL;
+       } else
+               stall_time = ctx->value;
+       udelay(stall_time);
+       return 0;
+}
+
+static int erst_exec_stall_while_true(struct apei_exec_context *ctx,
+                                     struct acpi_whea_header *entry)
+{
+       int rc;
+       u64 val;
+       u64 timeout = FIRMWARE_TIMEOUT;
+       u64 stall_time;
+
+       if (ctx->var1 > FIRMWARE_MAX_STALL) {
+               if (!in_nmi())
+                       pr_warning(FW_WARN ERST_PFX
+               "Too long stall time for stall while true instruction: %llx.\n",
+                                  ctx->var1);
+               stall_time = FIRMWARE_MAX_STALL;
+       } else
+               stall_time = ctx->var1;
+
+       for (;;) {
+               rc = __apei_exec_read_register(entry, &val);
+               if (rc)
+                       return rc;
+               if (val != ctx->value)
+                       break;
+               if (erst_timedout(&timeout, stall_time * NSEC_PER_USEC))
+                       return -EIO;
+       }
+       return 0;
+}
+
+static int erst_exec_skip_next_instruction_if_true(
+       struct apei_exec_context *ctx,
+       struct acpi_whea_header *entry)
+{
+       int rc;
+       u64 val;
+
+       rc = __apei_exec_read_register(entry, &val);
+       if (rc)
+               return rc;
+       if (val == ctx->value) {
+               ctx->ip += 2;
+               return APEI_EXEC_SET_IP;
+       }
+
+       return 0;
+}
+
+static int erst_exec_goto(struct apei_exec_context *ctx,
+                         struct acpi_whea_header *entry)
+{
+       ctx->ip = ctx->value;
+       return APEI_EXEC_SET_IP;
+}
+
+static int erst_exec_set_src_address_base(struct apei_exec_context *ctx,
+                                         struct acpi_whea_header *entry)
+{
+       return __apei_exec_read_register(entry, &ctx->src_base);
+}
+
+static int erst_exec_set_dst_address_base(struct apei_exec_context *ctx,
+                                         struct acpi_whea_header *entry)
+{
+       return __apei_exec_read_register(entry, &ctx->dst_base);
+}
+
+static int erst_exec_move_data(struct apei_exec_context *ctx,
+                              struct acpi_whea_header *entry)
+{
+       int rc;
+       u64 offset;
+
+       rc = __apei_exec_read_register(entry, &offset);
+       if (rc)
+               return rc;
+       memmove((void *)ctx->dst_base + offset,
+               (void *)ctx->src_base + offset,
+               ctx->var2);
+
+       return 0;
+}
+
+static struct apei_exec_ins_type erst_ins_type[] = {
+       [ACPI_ERST_READ_REGISTER] = {
+               .flags = APEI_EXEC_INS_ACCESS_REGISTER,
+               .run = apei_exec_read_register,
+       },
+       [ACPI_ERST_READ_REGISTER_VALUE] = {
+               .flags = APEI_EXEC_INS_ACCESS_REGISTER,
+               .run = apei_exec_read_register_value,
+       },
+       [ACPI_ERST_WRITE_REGISTER] = {
+               .flags = APEI_EXEC_INS_ACCESS_REGISTER,
+               .run = apei_exec_write_register,
+       },
+       [ACPI_ERST_WRITE_REGISTER_VALUE] = {
+               .flags = APEI_EXEC_INS_ACCESS_REGISTER,
+               .run = apei_exec_write_register_value,
+       },
+       [ACPI_ERST_NOOP] = {
+               .flags = 0,
+               .run = apei_exec_noop,
+       },
+       [ACPI_ERST_LOAD_VAR1] = {
+               .flags = APEI_EXEC_INS_ACCESS_REGISTER,
+               .run = erst_exec_load_var1,
+       },
+       [ACPI_ERST_LOAD_VAR2] = {
+               .flags = APEI_EXEC_INS_ACCESS_REGISTER,
+               .run = erst_exec_load_var2,
+       },
+       [ACPI_ERST_STORE_VAR1] = {
+               .flags = APEI_EXEC_INS_ACCESS_REGISTER,
+               .run = erst_exec_store_var1,
+       },
+       [ACPI_ERST_ADD] = {
+               .flags = 0,
+               .run = erst_exec_add,
+       },
+       [ACPI_ERST_SUBTRACT] = {
+               .flags = 0,
+               .run = erst_exec_subtract,
+       },
+       [ACPI_ERST_ADD_VALUE] = {
+               .flags = APEI_EXEC_INS_ACCESS_REGISTER,
+               .run = erst_exec_add_value,
+       },
+       [ACPI_ERST_SUBTRACT_VALUE] = {
+               .flags = APEI_EXEC_INS_ACCESS_REGISTER,
+               .run = erst_exec_subtract_value,
+       },
+       [ACPI_ERST_STALL] = {
+               .flags = 0,
+               .run = erst_exec_stall,
+       },
+       [ACPI_ERST_STALL_WHILE_TRUE] = {
+               .flags = APEI_EXEC_INS_ACCESS_REGISTER,
+               .run = erst_exec_stall_while_true,
+       },
+       [ACPI_ERST_SKIP_NEXT_IF_TRUE] = {
+               .flags = APEI_EXEC_INS_ACCESS_REGISTER,
+               .run = erst_exec_skip_next_instruction_if_true,
+       },
+       [ACPI_ERST_GOTO] = {
+               .flags = 0,
+               .run = erst_exec_goto,
+       },
+       [ACPI_ERST_SET_SRC_ADDRESS_BASE] = {
+               .flags = APEI_EXEC_INS_ACCESS_REGISTER,
+               .run = erst_exec_set_src_address_base,
+       },
+       [ACPI_ERST_SET_DST_ADDRESS_BASE] = {
+               .flags = APEI_EXEC_INS_ACCESS_REGISTER,
+               .run = erst_exec_set_dst_address_base,
+       },
+       [ACPI_ERST_MOVE_DATA] = {
+               .flags = APEI_EXEC_INS_ACCESS_REGISTER,
+               .run = erst_exec_move_data,
+       },
+};
+
+static inline void erst_exec_ctx_init(struct apei_exec_context *ctx)
+{
+       apei_exec_ctx_init(ctx, erst_ins_type, ARRAY_SIZE(erst_ins_type),
+                          ERST_TAB_ENTRY(erst_tab), erst_tab->entries);
+}
+
+static int erst_get_erange(struct erst_erange *range)
+{
+       struct apei_exec_context ctx;
+       int rc;
+
+       erst_exec_ctx_init(&ctx);
+       rc = apei_exec_run(&ctx, ACPI_ERST_GET_ERROR_RANGE);
+       if (rc)
+               return rc;
+       range->base = apei_exec_ctx_get_output(&ctx);
+       rc = apei_exec_run(&ctx, ACPI_ERST_GET_ERROR_LENGTH);
+       if (rc)
+               return rc;
+       range->size = apei_exec_ctx_get_output(&ctx);
+       rc = apei_exec_run(&ctx, ACPI_ERST_GET_ERROR_ATTRIBUTES);
+       if (rc)
+               return rc;
+       range->attr = apei_exec_ctx_get_output(&ctx);
+
+       return 0;
+}
+
+static ssize_t __erst_get_record_count(void)
+{
+       struct apei_exec_context ctx;
+       int rc;
+
+       erst_exec_ctx_init(&ctx);
+       rc = apei_exec_run(&ctx, ACPI_ERST_GET_RECORD_COUNT);
+       if (rc)
+               return rc;
+       return apei_exec_ctx_get_output(&ctx);
+}
+
+ssize_t erst_get_record_count(void)
+{
+       ssize_t count;
+       unsigned long flags;
+
+       if (erst_disable)
+               return -ENODEV;
+
+       spin_lock_irqsave(&erst_lock, flags);
+       count = __erst_get_record_count();
+       spin_unlock_irqrestore(&erst_lock, flags);
+
+       return count;
+}
+EXPORT_SYMBOL_GPL(erst_get_record_count);
+
+static int __erst_get_next_record_id(u64 *record_id)
+{
+       struct apei_exec_context ctx;
+       int rc;
+
+       erst_exec_ctx_init(&ctx);
+       rc = apei_exec_run(&ctx, ACPI_ERST_GET_RECORD_ID);
+       if (rc)
+               return rc;
+       *record_id = apei_exec_ctx_get_output(&ctx);
+
+       return 0;
+}
+
+/*
+ * Get the record ID of an existing error record on the persistent
+ * storage. If there is no error record on the persistent storage, the
+ * returned record_id is APEI_ERST_INVALID_RECORD_ID.
+ */
+int erst_get_next_record_id(u64 *record_id)
+{
+       int rc;
+       unsigned long flags;
+
+       if (erst_disable)
+               return -ENODEV;
+
+       spin_lock_irqsave(&erst_lock, flags);
+       rc = __erst_get_next_record_id(record_id);
+       spin_unlock_irqrestore(&erst_lock, flags);
+
+       return rc;
+}
+EXPORT_SYMBOL_GPL(erst_get_next_record_id);
+
+static int __erst_write_to_storage(u64 offset)
+{
+       struct apei_exec_context ctx;
+       u64 timeout = FIRMWARE_TIMEOUT;
+       u64 val;
+       int rc;
+
+       erst_exec_ctx_init(&ctx);
+       rc = apei_exec_run(&ctx, ACPI_ERST_BEGIN_WRITE);
+       if (rc)
+               return rc;
+       apei_exec_ctx_set_input(&ctx, offset);
+       rc = apei_exec_run(&ctx, ACPI_ERST_SET_RECORD_OFFSET);
+       if (rc)
+               return rc;
+       rc = apei_exec_run(&ctx, ACPI_ERST_EXECUTE_OPERATION);
+       if (rc)
+               return rc;
+       for (;;) {
+               rc = apei_exec_run(&ctx, ACPI_ERST_CHECK_BUSY_STATUS);
+               if (rc)
+                       return rc;
+               val = apei_exec_ctx_get_output(&ctx);
+               if (!val)
+                       break;
+               if (erst_timedout(&timeout, SPIN_UNIT))
+                       return -EIO;
+       }
+       rc = apei_exec_run(&ctx, ACPI_ERST_GET_COMMAND_STATUS);
+       if (rc)
+               return rc;
+       val = apei_exec_ctx_get_output(&ctx);
+       rc = apei_exec_run(&ctx, ACPI_ERST_END);
+       if (rc)
+               return rc;
+
+       return erst_errno(val);
+}
+
+static int __erst_read_from_storage(u64 record_id, u64 offset)
+{
+       struct apei_exec_context ctx;
+       u64 timeout = FIRMWARE_TIMEOUT;
+       u64 val;
+       int rc;
+
+       erst_exec_ctx_init(&ctx);
+       rc = apei_exec_run(&ctx, ACPI_ERST_BEGIN_READ);
+       if (rc)
+               return rc;
+       apei_exec_ctx_set_input(&ctx, offset);
+       rc = apei_exec_run(&ctx, ACPI_ERST_SET_RECORD_OFFSET);
+       if (rc)
+               return rc;
+       apei_exec_ctx_set_input(&ctx, record_id);
+       rc = apei_exec_run(&ctx, ACPI_ERST_SET_RECORD_ID);
+       if (rc)
+               return rc;
+       rc = apei_exec_run(&ctx, ACPI_ERST_EXECUTE_OPERATION);
+       if (rc)
+               return rc;
+       for (;;) {
+               rc = apei_exec_run(&ctx, ACPI_ERST_CHECK_BUSY_STATUS);
+               if (rc)
+                       return rc;
+               val = apei_exec_ctx_get_output(&ctx);
+               if (!val)
+                       break;
+               if (erst_timedout(&timeout, SPIN_UNIT))
+                       return -EIO;
+       };
+       rc = apei_exec_run(&ctx, ACPI_ERST_GET_COMMAND_STATUS);
+       if (rc)
+               return rc;
+       val = apei_exec_ctx_get_output(&ctx);
+       rc = apei_exec_run(&ctx, ACPI_ERST_END);
+       if (rc)
+               return rc;
+
+       return erst_errno(val);
+}
+
+static int __erst_clear_from_storage(u64 record_id)
+{
+       struct apei_exec_context ctx;
+       u64 timeout = FIRMWARE_TIMEOUT;
+       u64 val;
+       int rc;
+
+       erst_exec_ctx_init(&ctx);
+       rc = apei_exec_run(&ctx, ACPI_ERST_BEGIN_CLEAR);
+       if (rc)
+               return rc;
+       apei_exec_ctx_set_input(&ctx, record_id);
+       rc = apei_exec_run(&ctx, ACPI_ERST_SET_RECORD_ID);
+       if (rc)
+               return rc;
+       rc = apei_exec_run(&ctx, ACPI_ERST_EXECUTE_OPERATION);
+       if (rc)
+               return rc;
+       for (;;) {
+               rc = apei_exec_run(&ctx, ACPI_ERST_CHECK_BUSY_STATUS);
+               if (rc)
+                       return rc;
+               val = apei_exec_ctx_get_output(&ctx);
+               if (!val)
+                       break;
+               if (erst_timedout(&timeout, SPIN_UNIT))
+                       return -EIO;
+       }
+       rc = apei_exec_run(&ctx, ACPI_ERST_GET_COMMAND_STATUS);
+       if (rc)
+               return rc;
+       val = apei_exec_ctx_get_output(&ctx);
+       rc = apei_exec_run(&ctx, ACPI_ERST_END);
+       if (rc)
+               return rc;
+
+       return erst_errno(val);
+}
+
+/* NVRAM ERST Error Log Address Range is not supported yet */
+static void pr_unimpl_nvram(void)
+{
+       if (printk_ratelimit())
+               pr_warning(ERST_PFX
+               "NVRAM ERST Log Address Range is not implemented yet\n");
+}
+
+static int __erst_write_to_nvram(const struct cper_record_header *record)
+{
+       /* do not print message, because printk is not safe for NMI */
+       return -ENOSYS;
+}
+
+static int __erst_read_to_erange_from_nvram(u64 record_id, u64 *offset)
+{
+       pr_unimpl_nvram();
+       return -ENOSYS;
+}
+
+static int __erst_clear_from_nvram(u64 record_id)
+{
+       pr_unimpl_nvram();
+       return -ENOSYS;
+}
+
+int erst_write(const struct cper_record_header *record)
+{
+       int rc;
+       unsigned long flags;
+       struct cper_record_header *rcd_erange;
+
+       if (erst_disable)
+               return -ENODEV;
+
+       if (memcmp(record->signature, CPER_SIG_RECORD, CPER_SIG_SIZE))
+               return -EINVAL;
+
+       if (erst_erange.attr & ERST_RANGE_NVRAM) {
+               if (!spin_trylock_irqsave(&erst_lock, flags))
+                       return -EBUSY;
+               rc = __erst_write_to_nvram(record);
+               spin_unlock_irqrestore(&erst_lock, flags);
+               return rc;
+       }
+
+       if (record->record_length > erst_erange.size)
+               return -EINVAL;
+
+       if (!spin_trylock_irqsave(&erst_lock, flags))
+               return -EBUSY;
+       memcpy(erst_erange.vaddr, record, record->record_length);
+       rcd_erange = erst_erange.vaddr;
+       /* signature for serialization system */
+       memcpy(&rcd_erange->persistence_information, "ER", 2);
+
+       rc = __erst_write_to_storage(0);
+       spin_unlock_irqrestore(&erst_lock, flags);
+
+       return rc;
+}
+EXPORT_SYMBOL_GPL(erst_write);
+
+static int __erst_read_to_erange(u64 record_id, u64 *offset)
+{
+       int rc;
+
+       if (erst_erange.attr & ERST_RANGE_NVRAM)
+               return __erst_read_to_erange_from_nvram(
+                       record_id, offset);
+
+       rc = __erst_read_from_storage(record_id, 0);
+       if (rc)
+               return rc;
+       *offset = 0;
+
+       return 0;
+}
+
+static ssize_t __erst_read(u64 record_id, struct cper_record_header *record,
+                          size_t buflen)
+{
+       int rc;
+       u64 offset, len = 0;
+       struct cper_record_header *rcd_tmp;
+
+       rc = __erst_read_to_erange(record_id, &offset);
+       if (rc)
+               return rc;
+       rcd_tmp = erst_erange.vaddr + offset;
+       len = rcd_tmp->record_length;
+       if (len <= buflen)
+               memcpy(record, rcd_tmp, len);
+
+       return len;
+}
+
+/*
+ * If return value > buflen, the buffer size is not big enough,
+ * else if return value < 0, something goes wrong,
+ * else everything is OK, and return value is record length
+ */
+ssize_t erst_read(u64 record_id, struct cper_record_header *record,
+                 size_t buflen)
+{
+       ssize_t len;
+       unsigned long flags;
+
+       if (erst_disable)
+               return -ENODEV;
+
+       spin_lock_irqsave(&erst_lock, flags);
+       len = __erst_read(record_id, record, buflen);
+       spin_unlock_irqrestore(&erst_lock, flags);
+       return len;
+}
+EXPORT_SYMBOL_GPL(erst_read);
+
+/*
+ * If return value > buflen, the buffer size is not big enough,
+ * else if return value = 0, there is no more record to read,
+ * else if return value < 0, something goes wrong,
+ * else everything is OK, and return value is record length
+ */
+ssize_t erst_read_next(struct cper_record_header *record, size_t buflen)
+{
+       int rc;
+       ssize_t len;
+       unsigned long flags;
+       u64 record_id;
+
+       if (erst_disable)
+               return -ENODEV;
+
+       spin_lock_irqsave(&erst_lock, flags);
+       rc = __erst_get_next_record_id(&record_id);
+       if (rc) {
+               spin_unlock_irqrestore(&erst_lock, flags);
+               return rc;
+       }
+       /* no more record */
+       if (record_id == APEI_ERST_INVALID_RECORD_ID) {
+               spin_unlock_irqrestore(&erst_lock, flags);
+               return 0;
+       }
+
+       len = __erst_read(record_id, record, buflen);
+       spin_unlock_irqrestore(&erst_lock, flags);
+
+       return len;
+}
+EXPORT_SYMBOL_GPL(erst_read_next);
+
+int erst_clear(u64 record_id)
+{
+       int rc;
+       unsigned long flags;
+
+       if (erst_disable)
+               return -ENODEV;
+
+       spin_lock_irqsave(&erst_lock, flags);
+       if (erst_erange.attr & ERST_RANGE_NVRAM)
+               rc = __erst_clear_from_nvram(record_id);
+       else
+               rc = __erst_clear_from_storage(record_id);
+       spin_unlock_irqrestore(&erst_lock, flags);
+
+       return rc;
+}
+EXPORT_SYMBOL_GPL(erst_clear);
+
+static int __init setup_erst_disable(char *str)
+{
+       erst_disable = 1;
+       return 0;
+}
+
+__setup("erst_disable", setup_erst_disable);
+
+static int erst_check_table(struct acpi_table_erst *erst_tab)
+{
+       if (erst_tab->header_length != sizeof(struct acpi_table_erst))
+               return -EINVAL;
+       if (erst_tab->header.length < sizeof(struct acpi_table_erst))
+               return -EINVAL;
+       if (erst_tab->entries !=
+           (erst_tab->header.length - sizeof(struct acpi_table_erst)) /
+           sizeof(struct acpi_erst_entry))
+               return -EINVAL;
+
+       return 0;
+}
+
+static int __init erst_init(void)
+{
+       int rc = 0;
+       acpi_status status;
+       struct apei_exec_context ctx;
+       struct apei_resources erst_resources;
+       struct resource *r;
+
+       if (acpi_disabled)
+               goto err;
+
+       if (erst_disable) {
+               pr_info(ERST_PFX
+       "Error Record Serialization Table (ERST) support is disabled.\n");
+               goto err;
+       }
+
+       status = acpi_get_table(ACPI_SIG_ERST, 0,
+                               (struct acpi_table_header **)&erst_tab);
+       if (status == AE_NOT_FOUND) {
+               pr_err(ERST_PFX "Table is not found!\n");
+               goto err;
+       } else if (ACPI_FAILURE(status)) {
+               const char *msg = acpi_format_exception(status);
+               pr_err(ERST_PFX "Failed to get table, %s\n", msg);
+               rc = -EINVAL;
+               goto err;
+       }
+
+       rc = erst_check_table(erst_tab);
+       if (rc) {
+               pr_err(FW_BUG ERST_PFX "ERST table is invalid\n");
+               goto err;
+       }
+
+       apei_resources_init(&erst_resources);
+       erst_exec_ctx_init(&ctx);
+       rc = apei_exec_collect_resources(&ctx, &erst_resources);
+       if (rc)
+               goto err_fini;
+       rc = apei_resources_request(&erst_resources, "APEI ERST");
+       if (rc)
+               goto err_fini;
+       rc = apei_exec_pre_map_gars(&ctx);
+       if (rc)
+               goto err_release;
+       rc = erst_get_erange(&erst_erange);
+       if (rc) {
+               if (rc == -ENODEV)
+                       pr_info(ERST_PFX
+       "The corresponding hardware device or firmware implementation "
+       "is not available.\n");
+               else
+                       pr_err(ERST_PFX
+                              "Failed to get Error Log Address Range.\n");
+               goto err_unmap_reg;
+       }
+
+       r = request_mem_region(erst_erange.base, erst_erange.size, "APEI ERST");
+       if (!r) {
+               pr_err(ERST_PFX
+               "Can not request iomem region <0x%16llx-0x%16llx> for ERST.\n",
+               (unsigned long long)erst_erange.base,
+               (unsigned long long)erst_erange.base + erst_erange.size);
+               rc = -EIO;
+               goto err_unmap_reg;
+       }
+       rc = -ENOMEM;
+       erst_erange.vaddr = ioremap_cache(erst_erange.base,
+                                         erst_erange.size);
+       if (!erst_erange.vaddr)
+               goto err_release_erange;
+
+       pr_info(ERST_PFX
+       "Error Record Serialization Table (ERST) support is initialized.\n");
+
+       return 0;
+
+err_release_erange:
+       release_mem_region(erst_erange.base, erst_erange.size);
+err_unmap_reg:
+       apei_exec_post_unmap_gars(&ctx);
+err_release:
+       apei_resources_release(&erst_resources);
+err_fini:
+       apei_resources_fini(&erst_resources);
+err:
+       erst_disable = 1;
+       return rc;
+}
+
+device_initcall(erst_init);