diff --git a/drivers/acpi/tables.c b/drivers/acpi/tables.c
new file mode 100644
index 0000000..a3d012b
--- /dev/null
+++ b/drivers/acpi/tables.c
@@ -0,0 +1,796 @@
+/*
+ *  acpi_tables.c - ACPI Boot-Time Table Parsing
+ *
+ *  Copyright (C) 2001 Paul Diefenbaugh <paul.s.diefenbaugh@intel.com>
+ *
+ * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; either version 2 of the License, or
+ *  (at your option) any later version.
+ *
+ *  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.
+ *
+ * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ *
+ */
+
+/* Uncomment next line to get verbose printout */
+/* #define DEBUG */
+#define pr_fmt(fmt) "ACPI: " fmt
+
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/smp.h>
+#include <linux/string.h>
+#include <linux/types.h>
+#include <linux/irq.h>
+#include <linux/errno.h>
+#include <linux/acpi.h>
+#include <linux/bootmem.h>
+#include <linux/earlycpio.h>
+#include <linux/memblock.h>
+#include <linux/initrd.h>
+#include "internal.h"
+
+#ifdef CONFIG_ACPI_CUSTOM_DSDT
+#include CONFIG_ACPI_CUSTOM_DSDT_FILE
+#endif
+
+#define ACPI_MAX_TABLES		128
+
+static char *mps_inti_flags_polarity[] = { "dfl", "high", "res", "low" };
+static char *mps_inti_flags_trigger[] = { "dfl", "edge", "res", "level" };
+
+static struct acpi_table_desc initial_tables[ACPI_MAX_TABLES] __initdata;
+
+static int acpi_apic_instance __initdata;
+
+/*
+ * Disable table checksum verification for the early stage due to the size
+ * limitation of the current x86 early mapping implementation.
+ */
+static bool acpi_verify_table_checksum __initdata = false;
+
+void acpi_table_print_madt_entry(struct acpi_subtable_header *header)
+{
+	if (!header)
+		return;
+
+	switch (header->type) {
+
+	case ACPI_MADT_TYPE_LOCAL_APIC:
+		{
+			struct acpi_madt_local_apic *p =
+			    (struct acpi_madt_local_apic *)header;
+			pr_debug("LAPIC (acpi_id[0x%02x] lapic_id[0x%02x] %s)\n",
+				 p->processor_id, p->id,
+				 (p->lapic_flags & ACPI_MADT_ENABLED) ? "enabled" : "disabled");
+		}
+		break;
+
+	case ACPI_MADT_TYPE_LOCAL_X2APIC:
+		{
+			struct acpi_madt_local_x2apic *p =
+			    (struct acpi_madt_local_x2apic *)header;
+			pr_debug("X2APIC (apic_id[0x%02x] uid[0x%02x] %s)\n",
+				 p->local_apic_id, p->uid,
+				 (p->lapic_flags & ACPI_MADT_ENABLED) ? "enabled" : "disabled");
+		}
+		break;
+
+	case ACPI_MADT_TYPE_IO_APIC:
+		{
+			struct acpi_madt_io_apic *p =
+			    (struct acpi_madt_io_apic *)header;
+			pr_debug("IOAPIC (id[0x%02x] address[0x%08x] gsi_base[%d])\n",
+				 p->id, p->address, p->global_irq_base);
+		}
+		break;
+
+	case ACPI_MADT_TYPE_INTERRUPT_OVERRIDE:
+		{
+			struct acpi_madt_interrupt_override *p =
+			    (struct acpi_madt_interrupt_override *)header;
+			pr_info("INT_SRC_OVR (bus %d bus_irq %d global_irq %d %s %s)\n",
+				p->bus, p->source_irq, p->global_irq,
+				mps_inti_flags_polarity[p->inti_flags & ACPI_MADT_POLARITY_MASK],
+				mps_inti_flags_trigger[(p->inti_flags & ACPI_MADT_TRIGGER_MASK) >> 2]);
+			if (p->inti_flags  &
+			    ~(ACPI_MADT_POLARITY_MASK | ACPI_MADT_TRIGGER_MASK))
+				pr_info("INT_SRC_OVR unexpected reserved flags: 0x%x\n",
+					p->inti_flags  &
+					~(ACPI_MADT_POLARITY_MASK | ACPI_MADT_TRIGGER_MASK));
+		}
+		break;
+
+	case ACPI_MADT_TYPE_NMI_SOURCE:
+		{
+			struct acpi_madt_nmi_source *p =
+			    (struct acpi_madt_nmi_source *)header;
+			pr_info("NMI_SRC (%s %s global_irq %d)\n",
+				mps_inti_flags_polarity[p->inti_flags & ACPI_MADT_POLARITY_MASK],
+				mps_inti_flags_trigger[(p->inti_flags & ACPI_MADT_TRIGGER_MASK) >> 2],
+				p->global_irq);
+		}
+		break;
+
+	case ACPI_MADT_TYPE_LOCAL_APIC_NMI:
+		{
+			struct acpi_madt_local_apic_nmi *p =
+			    (struct acpi_madt_local_apic_nmi *)header;
+			pr_info("LAPIC_NMI (acpi_id[0x%02x] %s %s lint[0x%x])\n",
+				p->processor_id,
+				mps_inti_flags_polarity[p->inti_flags & ACPI_MADT_POLARITY_MASK	],
+				mps_inti_flags_trigger[(p->inti_flags & ACPI_MADT_TRIGGER_MASK) >> 2],
+				p->lint);
+		}
+		break;
+
+	case ACPI_MADT_TYPE_LOCAL_X2APIC_NMI:
+		{
+			u16 polarity, trigger;
+			struct acpi_madt_local_x2apic_nmi *p =
+			    (struct acpi_madt_local_x2apic_nmi *)header;
+
+			polarity = p->inti_flags & ACPI_MADT_POLARITY_MASK;
+			trigger = (p->inti_flags & ACPI_MADT_TRIGGER_MASK) >> 2;
+
+			pr_info("X2APIC_NMI (uid[0x%02x] %s %s lint[0x%x])\n",
+				p->uid,
+				mps_inti_flags_polarity[polarity],
+				mps_inti_flags_trigger[trigger],
+				p->lint);
+		}
+		break;
+
+	case ACPI_MADT_TYPE_LOCAL_APIC_OVERRIDE:
+		{
+			struct acpi_madt_local_apic_override *p =
+			    (struct acpi_madt_local_apic_override *)header;
+			pr_info("LAPIC_ADDR_OVR (address[%p])\n",
+				(void *)(unsigned long)p->address);
+		}
+		break;
+
+	case ACPI_MADT_TYPE_IO_SAPIC:
+		{
+			struct acpi_madt_io_sapic *p =
+			    (struct acpi_madt_io_sapic *)header;
+			pr_debug("IOSAPIC (id[0x%x] address[%p] gsi_base[%d])\n",
+				 p->id, (void *)(unsigned long)p->address,
+				 p->global_irq_base);
+		}
+		break;
+
+	case ACPI_MADT_TYPE_LOCAL_SAPIC:
+		{
+			struct acpi_madt_local_sapic *p =
+			    (struct acpi_madt_local_sapic *)header;
+			pr_debug("LSAPIC (acpi_id[0x%02x] lsapic_id[0x%02x] lsapic_eid[0x%02x] %s)\n",
+				 p->processor_id, p->id, p->eid,
+				 (p->lapic_flags & ACPI_MADT_ENABLED) ? "enabled" : "disabled");
+		}
+		break;
+
+	case ACPI_MADT_TYPE_INTERRUPT_SOURCE:
+		{
+			struct acpi_madt_interrupt_source *p =
+			    (struct acpi_madt_interrupt_source *)header;
+			pr_info("PLAT_INT_SRC (%s %s type[0x%x] id[0x%04x] eid[0x%x] iosapic_vector[0x%x] global_irq[0x%x]\n",
+				mps_inti_flags_polarity[p->inti_flags & ACPI_MADT_POLARITY_MASK],
+				mps_inti_flags_trigger[(p->inti_flags & ACPI_MADT_TRIGGER_MASK) >> 2],
+				p->type, p->id, p->eid, p->io_sapic_vector,
+				p->global_irq);
+		}
+		break;
+
+	case ACPI_MADT_TYPE_GENERIC_INTERRUPT:
+		{
+			struct acpi_madt_generic_interrupt *p =
+				(struct acpi_madt_generic_interrupt *)header;
+			pr_debug("GICC (acpi_id[0x%04x] address[%llx] MPIDR[0x%llx] %s)\n",
+				 p->uid, p->base_address,
+				 p->arm_mpidr,
+				 (p->flags & ACPI_MADT_ENABLED) ? "enabled" : "disabled");
+
+		}
+		break;
+
+	case ACPI_MADT_TYPE_GENERIC_DISTRIBUTOR:
+		{
+			struct acpi_madt_generic_distributor *p =
+				(struct acpi_madt_generic_distributor *)header;
+			pr_debug("GIC Distributor (gic_id[0x%04x] address[%llx] gsi_base[%d])\n",
+				 p->gic_id, p->base_address,
+				 p->global_irq_base);
+		}
+		break;
+
+	default:
+		pr_warn("Found unsupported MADT entry (type = 0x%x)\n",
+			header->type);
+		break;
+	}
+}
+
+/**
+ * acpi_parse_entries_array - for each proc_num find a suitable subtable
+ *
+ * @id: table id (for debugging purposes)
+ * @table_size: size of the root table
+ * @table_header: where does the table start?
+ * @proc: array of acpi_subtable_proc struct containing entry id
+ *        and associated handler with it
+ * @proc_num: how big proc is?
+ * @max_entries: how many entries can we process?
+ *
+ * For each proc_num find a subtable with proc->id and run proc->handler
+ * on it. Assumption is that there's only single handler for particular
+ * entry id.
+ *
+ * The table_size is not the size of the complete ACPI table (the length
+ * field in the header struct), but only the size of the root table; i.e.,
+ * the offset from the very first byte of the complete ACPI table, to the
+ * first byte of the very first subtable.
+ *
+ * On success returns sum of all matching entries for all proc handlers.
+ * Otherwise, -ENODEV or -EINVAL is returned.
+ */
+static int __init
+acpi_parse_entries_array(char *id, unsigned long table_size,
+		struct acpi_table_header *table_header,
+		struct acpi_subtable_proc *proc, int proc_num,
+		unsigned int max_entries)
+{
+	struct acpi_subtable_header *entry;
+	unsigned long table_end;
+	int count = 0;
+	int errs = 0;
+	int i;
+
+	if (acpi_disabled)
+		return -ENODEV;
+
+	if (!id)
+		return -EINVAL;
+
+	if (!table_size)
+		return -EINVAL;
+
+	if (!table_header) {
+		pr_warn("%4.4s not present\n", id);
+		return -ENODEV;
+	}
+
+	table_end = (unsigned long)table_header + table_header->length;
+
+	/* Parse all entries looking for a match. */
+
+	entry = (struct acpi_subtable_header *)
+	    ((unsigned long)table_header + table_size);
+
+	while (((unsigned long)entry) + sizeof(struct acpi_subtable_header) <
+	       table_end) {
+		if (max_entries && count >= max_entries)
+			break;
+
+		for (i = 0; i < proc_num; i++) {
+			if (entry->type != proc[i].id)
+				continue;
+			if (!proc[i].handler ||
+			     (!errs && proc[i].handler(entry, table_end))) {
+				errs++;
+				continue;
+			}
+
+			proc[i].count++;
+			break;
+		}
+		if (i != proc_num)
+			count++;
+
+		/*
+		 * If entry->length is 0, break from this loop to avoid
+		 * infinite loop.
+		 */
+		if (entry->length == 0) {
+			pr_err("[%4.4s:0x%02x] Invalid zero length\n", id, proc->id);
+			return -EINVAL;
+		}
+
+		entry = (struct acpi_subtable_header *)
+		    ((unsigned long)entry + entry->length);
+	}
+
+	if (max_entries && count > max_entries) {
+		pr_warn("[%4.4s:0x%02x] found the maximum %i entries\n",
+			id, proc->id, count);
+	}
+
+	return errs ? -EINVAL : count;
+}
+
+int __init
+acpi_table_parse_entries_array(char *id,
+			 unsigned long table_size,
+			 struct acpi_subtable_proc *proc, int proc_num,
+			 unsigned int max_entries)
+{
+	struct acpi_table_header *table_header = NULL;
+	int count;
+	u32 instance = 0;
+
+	if (acpi_disabled)
+		return -ENODEV;
+
+	if (!id)
+		return -EINVAL;
+
+	if (!strncmp(id, ACPI_SIG_MADT, 4))
+		instance = acpi_apic_instance;
+
+	acpi_get_table(id, instance, &table_header);
+	if (!table_header) {
+		pr_warn("%4.4s not present\n", id);
+		return -ENODEV;
+	}
+
+	count = acpi_parse_entries_array(id, table_size, table_header,
+			proc, proc_num, max_entries);
+
+	acpi_put_table(table_header);
+	return count;
+}
+
+int __init
+acpi_table_parse_entries(char *id,
+			unsigned long table_size,
+			int entry_id,
+			acpi_tbl_entry_handler handler,
+			unsigned int max_entries)
+{
+	struct acpi_subtable_proc proc = {
+		.id		= entry_id,
+		.handler	= handler,
+	};
+
+	return acpi_table_parse_entries_array(id, table_size, &proc, 1,
+						max_entries);
+}
+
+int __init
+acpi_table_parse_madt(enum acpi_madt_type id,
+		      acpi_tbl_entry_handler handler, unsigned int max_entries)
+{
+	return acpi_table_parse_entries(ACPI_SIG_MADT,
+					    sizeof(struct acpi_table_madt), id,
+					    handler, max_entries);
+}
+
+/**
+ * acpi_table_parse - find table with @id, run @handler on it
+ * @id: table id to find
+ * @handler: handler to run
+ *
+ * Scan the ACPI System Descriptor Table (STD) for a table matching @id,
+ * run @handler on it.
+ *
+ * Return 0 if table found, -errno if not.
+ */
+int __init acpi_table_parse(char *id, acpi_tbl_table_handler handler)
+{
+	struct acpi_table_header *table = NULL;
+
+	if (acpi_disabled)
+		return -ENODEV;
+
+	if (!id || !handler)
+		return -EINVAL;
+
+	if (strncmp(id, ACPI_SIG_MADT, 4) == 0)
+		acpi_get_table(id, acpi_apic_instance, &table);
+	else
+		acpi_get_table(id, 0, &table);
+
+	if (table) {
+		handler(table);
+		acpi_put_table(table);
+		return 0;
+	} else
+		return -ENODEV;
+}
+
+/*
+ * The BIOS is supposed to supply a single APIC/MADT,
+ * but some report two.  Provide a knob to use either.
+ * (don't you wish instance 0 and 1 were not the same?)
+ */
+static void __init check_multiple_madt(void)
+{
+	struct acpi_table_header *table = NULL;
+
+	acpi_get_table(ACPI_SIG_MADT, 2, &table);
+	if (table) {
+		pr_warn("BIOS bug: multiple APIC/MADT found, using %d\n",
+			acpi_apic_instance);
+		pr_warn("If \"acpi_apic_instance=%d\" works better, "
+			"notify linux-acpi@vger.kernel.org\n",
+			acpi_apic_instance ? 0 : 2);
+		acpi_put_table(table);
+
+	} else
+		acpi_apic_instance = 0;
+
+	return;
+}
+
+static void acpi_table_taint(struct acpi_table_header *table)
+{
+	pr_warn("Override [%4.4s-%8.8s], this is unsafe: tainting kernel\n",
+		table->signature, table->oem_table_id);
+	add_taint(TAINT_OVERRIDDEN_ACPI_TABLE, LOCKDEP_NOW_UNRELIABLE);
+}
+
+#ifdef CONFIG_ACPI_TABLE_UPGRADE
+static u64 acpi_tables_addr;
+static int all_tables_size;
+
+/* Copied from acpica/tbutils.c:acpi_tb_checksum() */
+static u8 __init acpi_table_checksum(u8 *buffer, u32 length)
+{
+	u8 sum = 0;
+	u8 *end = buffer + length;
+
+	while (buffer < end)
+		sum = (u8) (sum + *(buffer++));
+	return sum;
+}
+
+/* All but ACPI_SIG_RSDP and ACPI_SIG_FACS: */
+static const char * const table_sigs[] = {
+	ACPI_SIG_BERT, ACPI_SIG_CPEP, ACPI_SIG_ECDT, ACPI_SIG_EINJ,
+	ACPI_SIG_ERST, ACPI_SIG_HEST, ACPI_SIG_MADT, ACPI_SIG_MSCT,
+	ACPI_SIG_SBST, ACPI_SIG_SLIT, ACPI_SIG_SRAT, ACPI_SIG_ASF,
+	ACPI_SIG_BOOT, ACPI_SIG_DBGP, ACPI_SIG_DMAR, ACPI_SIG_HPET,
+	ACPI_SIG_IBFT, ACPI_SIG_IVRS, ACPI_SIG_MCFG, ACPI_SIG_MCHI,
+	ACPI_SIG_SLIC, ACPI_SIG_SPCR, ACPI_SIG_SPMI, ACPI_SIG_TCPA,
+	ACPI_SIG_UEFI, ACPI_SIG_WAET, ACPI_SIG_WDAT, ACPI_SIG_WDDT,
+	ACPI_SIG_WDRT, ACPI_SIG_DSDT, ACPI_SIG_FADT, ACPI_SIG_PSDT,
+	ACPI_SIG_RSDT, ACPI_SIG_XSDT, ACPI_SIG_SSDT, ACPI_SIG_IORT,
+	ACPI_SIG_NFIT, ACPI_SIG_HMAT, ACPI_SIG_PPTT, NULL };
+
+#define ACPI_HEADER_SIZE sizeof(struct acpi_table_header)
+
+#define NR_ACPI_INITRD_TABLES 64
+static struct cpio_data __initdata acpi_initrd_files[NR_ACPI_INITRD_TABLES];
+static DECLARE_BITMAP(acpi_initrd_installed, NR_ACPI_INITRD_TABLES);
+
+#define MAP_CHUNK_SIZE   (NR_FIX_BTMAPS << PAGE_SHIFT)
+
+void __init acpi_table_upgrade(void)
+{
+	void *data = (void *)initrd_start;
+	size_t size = initrd_end - initrd_start;
+	int sig, no, table_nr = 0, total_offset = 0;
+	long offset = 0;
+	struct acpi_table_header *table;
+	char cpio_path[32] = "kernel/firmware/acpi/";
+	struct cpio_data file;
+
+	if (data == NULL || size == 0)
+		return;
+
+	for (no = 0; no < NR_ACPI_INITRD_TABLES; no++) {
+		file = find_cpio_data(cpio_path, data, size, &offset);
+		if (!file.data)
+			break;
+
+		data += offset;
+		size -= offset;
+
+		if (file.size < sizeof(struct acpi_table_header)) {
+			pr_err("ACPI OVERRIDE: Table smaller than ACPI header [%s%s]\n",
+				cpio_path, file.name);
+			continue;
+		}
+
+		table = file.data;
+
+		for (sig = 0; table_sigs[sig]; sig++)
+			if (!memcmp(table->signature, table_sigs[sig], 4))
+				break;
+
+		if (!table_sigs[sig]) {
+			pr_err("ACPI OVERRIDE: Unknown signature [%s%s]\n",
+				cpio_path, file.name);
+			continue;
+		}
+		if (file.size != table->length) {
+			pr_err("ACPI OVERRIDE: File length does not match table length [%s%s]\n",
+				cpio_path, file.name);
+			continue;
+		}
+		if (acpi_table_checksum(file.data, table->length)) {
+			pr_err("ACPI OVERRIDE: Bad table checksum [%s%s]\n",
+				cpio_path, file.name);
+			continue;
+		}
+
+		pr_info("%4.4s ACPI table found in initrd [%s%s][0x%x]\n",
+			table->signature, cpio_path, file.name, table->length);
+
+		all_tables_size += table->length;
+		acpi_initrd_files[table_nr].data = file.data;
+		acpi_initrd_files[table_nr].size = file.size;
+		table_nr++;
+	}
+	if (table_nr == 0)
+		return;
+
+	acpi_tables_addr =
+		memblock_find_in_range(0, ACPI_TABLE_UPGRADE_MAX_PHYS,
+				       all_tables_size, PAGE_SIZE);
+	if (!acpi_tables_addr) {
+		WARN_ON(1);
+		return;
+	}
+	/*
+	 * Only calling e820_add_reserve does not work and the
+	 * tables are invalid (memory got used) later.
+	 * memblock_reserve works as expected and the tables won't get modified.
+	 * But it's not enough on X86 because ioremap will
+	 * complain later (used by acpi_os_map_memory) that the pages
+	 * that should get mapped are not marked "reserved".
+	 * Both memblock_reserve and e820__range_add (via arch_reserve_mem_area)
+	 * works fine.
+	 */
+	memblock_reserve(acpi_tables_addr, all_tables_size);
+	arch_reserve_mem_area(acpi_tables_addr, all_tables_size);
+
+	/*
+	 * early_ioremap only can remap 256k one time. If we map all
+	 * tables one time, we will hit the limit. Need to map chunks
+	 * one by one during copying the same as that in relocate_initrd().
+	 */
+	for (no = 0; no < table_nr; no++) {
+		unsigned char *src_p = acpi_initrd_files[no].data;
+		phys_addr_t size = acpi_initrd_files[no].size;
+		phys_addr_t dest_addr = acpi_tables_addr + total_offset;
+		phys_addr_t slop, clen;
+		char *dest_p;
+
+		total_offset += size;
+
+		while (size) {
+			slop = dest_addr & ~PAGE_MASK;
+			clen = size;
+			if (clen > MAP_CHUNK_SIZE - slop)
+				clen = MAP_CHUNK_SIZE - slop;
+			dest_p = early_memremap(dest_addr & PAGE_MASK,
+						clen + slop);
+			memcpy(dest_p + slop, src_p, clen);
+			early_memunmap(dest_p, clen + slop);
+			src_p += clen;
+			dest_addr += clen;
+			size -= clen;
+		}
+	}
+}
+
+static acpi_status
+acpi_table_initrd_override(struct acpi_table_header *existing_table,
+			   acpi_physical_address *address, u32 *length)
+{
+	int table_offset = 0;
+	int table_index = 0;
+	struct acpi_table_header *table;
+	u32 table_length;
+
+	*length = 0;
+	*address = 0;
+	if (!acpi_tables_addr)
+		return AE_OK;
+
+	while (table_offset + ACPI_HEADER_SIZE <= all_tables_size) {
+		table = acpi_os_map_memory(acpi_tables_addr + table_offset,
+					   ACPI_HEADER_SIZE);
+		if (table_offset + table->length > all_tables_size) {
+			acpi_os_unmap_memory(table, ACPI_HEADER_SIZE);
+			WARN_ON(1);
+			return AE_OK;
+		}
+
+		table_length = table->length;
+
+		/* Only override tables matched */
+		if (memcmp(existing_table->signature, table->signature, 4) ||
+		    memcmp(table->oem_id, existing_table->oem_id,
+			   ACPI_OEM_ID_SIZE) ||
+		    memcmp(table->oem_table_id, existing_table->oem_table_id,
+			   ACPI_OEM_TABLE_ID_SIZE)) {
+			acpi_os_unmap_memory(table, ACPI_HEADER_SIZE);
+			goto next_table;
+		}
+		/*
+		 * Mark the table to avoid being used in
+		 * acpi_table_initrd_scan() and check the revision.
+		 */
+		if (test_and_set_bit(table_index, acpi_initrd_installed) ||
+		    existing_table->oem_revision >= table->oem_revision) {
+			acpi_os_unmap_memory(table, ACPI_HEADER_SIZE);
+			goto next_table;
+		}
+
+		*length = table_length;
+		*address = acpi_tables_addr + table_offset;
+		pr_info("Table Upgrade: override [%4.4s-%6.6s-%8.8s]\n",
+			table->signature, table->oem_id,
+			table->oem_table_id);
+		acpi_os_unmap_memory(table, ACPI_HEADER_SIZE);
+		break;
+
+next_table:
+		table_offset += table_length;
+		table_index++;
+	}
+	return AE_OK;
+}
+
+static void __init acpi_table_initrd_scan(void)
+{
+	int table_offset = 0;
+	int table_index = 0;
+	u32 table_length;
+	struct acpi_table_header *table;
+
+	if (!acpi_tables_addr)
+		return;
+
+	while (table_offset + ACPI_HEADER_SIZE <= all_tables_size) {
+		table = acpi_os_map_memory(acpi_tables_addr + table_offset,
+					   ACPI_HEADER_SIZE);
+		if (table_offset + table->length > all_tables_size) {
+			acpi_os_unmap_memory(table, ACPI_HEADER_SIZE);
+			WARN_ON(1);
+			return;
+		}
+
+		table_length = table->length;
+
+		/* Skip RSDT/XSDT which should only be used for override */
+		if (ACPI_COMPARE_NAME(table->signature, ACPI_SIG_RSDT) ||
+		    ACPI_COMPARE_NAME(table->signature, ACPI_SIG_XSDT)) {
+			acpi_os_unmap_memory(table, ACPI_HEADER_SIZE);
+			goto next_table;
+		}
+		/*
+		 * Mark the table to avoid being used in
+		 * acpi_table_initrd_override(). Though this is not possible
+		 * because override is disabled in acpi_install_table().
+		 */
+		if (test_and_set_bit(table_index, acpi_initrd_installed)) {
+			acpi_os_unmap_memory(table, ACPI_HEADER_SIZE);
+			goto next_table;
+		}
+
+		pr_info("Table Upgrade: install [%4.4s-%6.6s-%8.8s]\n",
+			table->signature, table->oem_id,
+			table->oem_table_id);
+		acpi_os_unmap_memory(table, ACPI_HEADER_SIZE);
+		acpi_install_table(acpi_tables_addr + table_offset, TRUE);
+next_table:
+		table_offset += table_length;
+		table_index++;
+	}
+}
+#else
+static acpi_status
+acpi_table_initrd_override(struct acpi_table_header *existing_table,
+			   acpi_physical_address *address,
+			   u32 *table_length)
+{
+	*table_length = 0;
+	*address = 0;
+	return AE_OK;
+}
+
+static void __init acpi_table_initrd_scan(void)
+{
+}
+#endif /* CONFIG_ACPI_TABLE_UPGRADE */
+
+acpi_status
+acpi_os_physical_table_override(struct acpi_table_header *existing_table,
+				acpi_physical_address *address,
+				u32 *table_length)
+{
+	return acpi_table_initrd_override(existing_table, address,
+					  table_length);
+}
+
+acpi_status
+acpi_os_table_override(struct acpi_table_header *existing_table,
+		       struct acpi_table_header **new_table)
+{
+	if (!existing_table || !new_table)
+		return AE_BAD_PARAMETER;
+
+	*new_table = NULL;
+
+#ifdef CONFIG_ACPI_CUSTOM_DSDT
+	if (strncmp(existing_table->signature, "DSDT", 4) == 0)
+		*new_table = (struct acpi_table_header *)AmlCode;
+#endif
+	if (*new_table != NULL)
+		acpi_table_taint(existing_table);
+	return AE_OK;
+}
+
+/*
+ * acpi_table_init()
+ *
+ * find RSDP, find and checksum SDT/XSDT.
+ * checksum all tables, print SDT/XSDT
+ *
+ * result: sdt_entry[] is initialized
+ */
+
+int __init acpi_table_init(void)
+{
+	acpi_status status;
+
+	if (acpi_verify_table_checksum) {
+		pr_info("Early table checksum verification enabled\n");
+		acpi_gbl_enable_table_validation = TRUE;
+	} else {
+		pr_info("Early table checksum verification disabled\n");
+		acpi_gbl_enable_table_validation = FALSE;
+	}
+
+	status = acpi_initialize_tables(initial_tables, ACPI_MAX_TABLES, 0);
+	if (ACPI_FAILURE(status))
+		return -EINVAL;
+	acpi_table_initrd_scan();
+
+	check_multiple_madt();
+	return 0;
+}
+
+static int __init acpi_parse_apic_instance(char *str)
+{
+	if (!str)
+		return -EINVAL;
+
+	if (kstrtoint(str, 0, &acpi_apic_instance))
+		return -EINVAL;
+
+	pr_notice("Shall use APIC/MADT table %d\n", acpi_apic_instance);
+
+	return 0;
+}
+
+early_param("acpi_apic_instance", acpi_parse_apic_instance);
+
+static int __init acpi_force_table_verification_setup(char *s)
+{
+	acpi_verify_table_checksum = true;
+
+	return 0;
+}
+
+early_param("acpi_force_table_verification", acpi_force_table_verification_setup);
+
+static int __init acpi_force_32bit_fadt_addr(char *s)
+{
+	pr_info("Forcing 32 Bit FADT addresses\n");
+	acpi_gbl_use32_bit_fadt_addresses = TRUE;
+
+	return 0;
+}
+
+early_param("acpi_force_32bit_fadt_addr", acpi_force_32bit_fadt_addr);