/*
 * Copyright 2008, Dustin Howett, dustin.howett@gmail.com. All rights reserved.
 * Copyright 2007, Michael Lotz, mmlr@mlotz.ch
 * Copyright 2004-2005, Axel Dörfler, axeld@pinc-software.de.
 * Distributed under the terms of the MIT License.
 *
 * Copyright 2001, Travis Geiselbrecht. All rights reserved.
 * Distributed under the terms of the NewOS License.
*/


#include "acpi.h"
#include "mmu.h"

#include <string.h>

#include <KernelExport.h>

#include <arch/x86/arch_acpi.h>


//#define TRACE_ACPI
#ifdef TRACE_ACPI
#	define TRACE(x) dprintf x
#else
#	define TRACE(x) ;
#endif

static struct scan_spots_struct acpi_scan_spots[] = {
	{ 0x0, 0x400, 0x400 - 0x0 },
	{ 0xe0000, 0x100000, 0x100000 - 0xe0000 },
	{ 0, 0, 0 }
};

static acpi_descriptor_header *sAcpiRsdt; // System Description Table


static status_t
acpi_check_rsdt(acpi_rsdp *rsdp)
{
	TRACE(("acpi: found rsdp at %p oem id: %.6s\n", rsdp, rsdp->oem_id));
	TRACE(("acpi: rsdp points to rsdt at 0x%lx\n", rsdp->rsdt_address));

	// map and validate the root system description table
	acpi_descriptor_header *rsdt
		= (acpi_descriptor_header *)mmu_map_physical_memory(
		rsdp->rsdt_address, B_PAGE_SIZE, kDefaultPageFlags);
	if (rsdt == NULL || strncmp(rsdt->signature, ACPI_RSDT_SIGNATURE, 4) != 0) {
		TRACE(("acpi: invalid root system description table\n"));
		return B_ERROR;
	}

	sAcpiRsdt = rsdt;
	return B_OK;
}


acpi_descriptor_header *
acpi_find_table(char *signature)
{
	if (sAcpiRsdt == NULL)
		return NULL;

	// Tried to keep numEntries a static variable; kept turning up 0 on table
	// scan
	// TODO: This calculates numEntries for every acpi probe.
	int32 numEntries = (sAcpiRsdt->length - sizeof(acpi_descriptor_header)) / 4;
	if (numEntries <= 0) {
		TRACE(("acpi: root system description table is empty\n"));
		return NULL;
	}

	TRACE(("acpi: searching %ld entries for table '%.4s'\n", numEntries,
		signature));

	uint32 *pointer = (uint32 *)((uint8 *)sAcpiRsdt
		+ sizeof(acpi_descriptor_header));

	for (int32 j = 0; j < numEntries; j++, pointer++) {
		acpi_descriptor_header *header = (acpi_descriptor_header *)
			mmu_map_physical_memory(*pointer, B_PAGE_SIZE, kDefaultPageFlags);
		if (header == NULL || strncmp(header->signature, signature, 4) != 0) {
			// not interesting for us
			TRACE(("acpi: Looking for '%.4s'. Skipping '%.4s'\n", signature,
				header->signature));
			continue;
		}
		TRACE(("acpi: Found '%.4s' @ %p\n", signature, pointer));
		return header;
	}

	// If we didn't find the table, return NULL.
	return NULL;
}


void
acpi_init(void)
{
	// Try to find the ACPI RSDP.
	for (int32 i = 0; acpi_scan_spots[i].length > 0; i++) {
		acpi_rsdp *rsdp = NULL;

		TRACE(("acpi_init: entry base 0x%lx, limit 0x%lx\n",
			acpi_scan_spots[i].start, acpi_scan_spots[i].stop));

		for (char *pointer = (char *)acpi_scan_spots[i].start;
		     (uint32)pointer < acpi_scan_spots[i].stop; pointer += 16) {
			if (strncmp(pointer, ACPI_RSDP_SIGNATURE, 8) == 0) {
				TRACE(("acpi_init: found ACPI RSDP signature at %p\n", pointer));
				rsdp = (acpi_rsdp *)pointer;
			}
		}

		if (rsdp != NULL && acpi_check_rsdt(rsdp) == B_OK)
			break;
	}
}