#include <linux/kernel.h>
#include <linux/types.h>
#include <linux/init.h>
#include <linux/bootmem.h>
#include <linux/ioport.h>
#include <linux/string.h>
#include <linux/kexec.h>
#include <linux/module.h>
#include <linux/mm.h>
#include <linux/pfn.h>
#include <linux/uaccess.h>

#include <asm/pgtable.h>
#include <asm/page.h>
#include <asm/e820.h>
#include <asm/setup.h>

static struct resource system_rom_resource = {
	.name	= "System ROM",
	.start	= 0xf0000,
	.end	= 0xfffff,
	.flags	= IORESOURCE_BUSY | IORESOURCE_READONLY | IORESOURCE_MEM
};

static struct resource extension_rom_resource = {
	.name	= "Extension ROM",
	.start	= 0xe0000,
	.end	= 0xeffff,
	.flags	= IORESOURCE_BUSY | IORESOURCE_READONLY | IORESOURCE_MEM
};

static struct resource adapter_rom_resources[] = { {
	.name 	= "Adapter ROM",
	.start	= 0xc8000,
	.end	= 0,
	.flags	= IORESOURCE_BUSY | IORESOURCE_READONLY | IORESOURCE_MEM
}, {
	.name 	= "Adapter ROM",
	.start	= 0,
	.end	= 0,
	.flags	= IORESOURCE_BUSY | IORESOURCE_READONLY | IORESOURCE_MEM
}, {
	.name 	= "Adapter ROM",
	.start	= 0,
	.end	= 0,
	.flags	= IORESOURCE_BUSY | IORESOURCE_READONLY | IORESOURCE_MEM
}, {
	.name 	= "Adapter ROM",
	.start	= 0,
	.end	= 0,
	.flags	= IORESOURCE_BUSY | IORESOURCE_READONLY | IORESOURCE_MEM
}, {
	.name 	= "Adapter ROM",
	.start	= 0,
	.end	= 0,
	.flags	= IORESOURCE_BUSY | IORESOURCE_READONLY | IORESOURCE_MEM
}, {
	.name 	= "Adapter ROM",
	.start	= 0,
	.end	= 0,
	.flags	= IORESOURCE_BUSY | IORESOURCE_READONLY | IORESOURCE_MEM
} };

static struct resource video_rom_resource = {
	.name 	= "Video ROM",
	.start	= 0xc0000,
	.end	= 0xc7fff,
	.flags	= IORESOURCE_BUSY | IORESOURCE_READONLY | IORESOURCE_MEM
};

#define ROMSIGNATURE 0xaa55

static int __init romsignature(const unsigned char *rom)
{
	const unsigned short * const ptr = (const unsigned short *)rom;
	unsigned short sig;

	return probe_kernel_address(ptr, sig) == 0 && sig == ROMSIGNATURE;
}

static int __init romchecksum(const unsigned char *rom, unsigned long length)
{
	unsigned char sum, c;

	for (sum = 0; length && probe_kernel_address(rom++, c) == 0; length--)
		sum += c;
	return !length && !sum;
}

static void __init probe_roms(void)
{
	const unsigned char *rom;
	unsigned long start, length, upper;
	unsigned char c;
	int i;

	/* video rom */
	upper = adapter_rom_resources[0].start;
	for (start = video_rom_resource.start; start < upper; start += 2048) {
		rom = isa_bus_to_virt(start);
		if (!romsignature(rom))
			continue;

		video_rom_resource.start = start;

		if (probe_kernel_address(rom + 2, c) != 0)
			continue;

		/* 0 < length <= 0x7f * 512, historically */
		length = c * 512;

		/* if checksum okay, trust length byte */
		if (length && romchecksum(rom, length))
			video_rom_resource.end = start + length - 1;

		request_resource(&iomem_resource, &video_rom_resource);
		break;
	}

	start = (video_rom_resource.end + 1 + 2047) & ~2047UL;
	if (start < upper)
		start = upper;

	/* system rom */
	request_resource(&iomem_resource, &system_rom_resource);
	upper = system_rom_resource.start;

	/* check for extension rom (ignore length byte!) */
	rom = isa_bus_to_virt(extension_rom_resource.start);
	if (romsignature(rom)) {
		length = extension_rom_resource.end - extension_rom_resource.start + 1;
		if (romchecksum(rom, length)) {
			request_resource(&iomem_resource, &extension_rom_resource);
			upper = extension_rom_resource.start;
		}
	}

	/* check for adapter roms on 2k boundaries */
	for (i = 0; i < ARRAY_SIZE(adapter_rom_resources) && start < upper; start += 2048) {
		rom = isa_bus_to_virt(start);
		if (!romsignature(rom))
			continue;

		if (probe_kernel_address(rom + 2, c) != 0)
			continue;

		/* 0 < length <= 0x7f * 512, historically */
		length = c * 512;

		/* but accept any length that fits if checksum okay */
		if (!length || start + length > upper || !romchecksum(rom, length))
			continue;

		adapter_rom_resources[i].start = start;
		adapter_rom_resources[i].end = start + length - 1;
		request_resource(&iomem_resource, &adapter_rom_resources[i]);

		start = adapter_rom_resources[i++].end & ~2047UL;
	}
}

/*
 * Request address space for all standard RAM and ROM resources
 * and also for regions reported as reserved by the e820.
 */
void __init init_iomem_resources(struct resource *code_resource,
		struct resource *data_resource,
		struct resource *bss_resource)
{
	int i;

	probe_roms();
	for (i = 0; i < e820.nr_map; i++) {
		struct resource *res;
#ifndef CONFIG_RESOURCES_64BIT
		if (e820.map[i].addr + e820.map[i].size > 0x100000000ULL)
			continue;
#endif
		res = kzalloc(sizeof(struct resource), GFP_ATOMIC);
		switch (e820.map[i].type) {
		case E820_RAM:	res->name = "System RAM"; break;
		case E820_ACPI:	res->name = "ACPI Tables"; break;
		case E820_NVS:	res->name = "ACPI Non-volatile Storage"; break;
		default:	res->name = "reserved";
		}
		res->start = e820.map[i].addr;
		res->end = res->start + e820.map[i].size - 1;
		res->flags = IORESOURCE_MEM | IORESOURCE_BUSY;
		if (request_resource(&iomem_resource, res)) {
			kfree(res);
			continue;
		}
		if (e820.map[i].type == E820_RAM) {
			/*
			 *  We don't know which RAM region contains kernel data,
			 *  so we try it repeatedly and let the resource manager
			 *  test it.
			 */
			request_resource(res, code_resource);
			request_resource(res, data_resource);
			request_resource(res, bss_resource);
#ifdef CONFIG_KEXEC
			if (crashk_res.start != crashk_res.end)
				request_resource(res, &crashk_res);
#endif
		}
	}
}

/*
 * Find the highest page frame number we have available
 */
void __init find_max_pfn(void)
{
	int i;

	max_pfn = 0;

	for (i = 0; i < e820.nr_map; i++) {
		unsigned long start, end;
		/* RAM? */
		if (e820.map[i].type != E820_RAM)
			continue;
		start = PFN_UP(e820.map[i].addr);
		end = PFN_DOWN(e820.map[i].addr + e820.map[i].size);
		if (start >= end)
			continue;
		if (end > max_pfn)
			max_pfn = end;
	}
}

/*
 * Register fully available low RAM pages with the bootmem allocator.
 */
void __init register_bootmem_low_pages(unsigned long max_low_pfn)
{
	int i;

	for (i = 0; i < e820.nr_map; i++) {
		unsigned long curr_pfn, last_pfn, size;
		/*
		 * Reserve usable low memory
		 */
		if (e820.map[i].type != E820_RAM)
			continue;
		/*
		 * We are rounding up the start address of usable memory:
		 */
		curr_pfn = PFN_UP(e820.map[i].addr);
		if (curr_pfn >= max_low_pfn)
			continue;
		/*
		 * ... and at the end of the usable range downwards:
		 */
		last_pfn = PFN_DOWN(e820.map[i].addr + e820.map[i].size);

		if (last_pfn > max_low_pfn)
			last_pfn = max_low_pfn;

		/*
		 * .. finally, did all the rounding and playing
		 * around just make the area go away?
		 */
		if (last_pfn <= curr_pfn)
			continue;

		size = last_pfn - curr_pfn;
		free_bootmem(PFN_PHYS(curr_pfn), PFN_PHYS(size));
	}
}

void __init limit_regions(unsigned long long size)
{
	unsigned long long current_addr;
	int i;

	e820_print_map("limit_regions start");
	for (i = 0; i < e820.nr_map; i++) {
		current_addr = e820.map[i].addr + e820.map[i].size;
		if (current_addr < size)
			continue;

		if (e820.map[i].type != E820_RAM)
			continue;

		if (e820.map[i].addr >= size) {
			/*
			 * This region starts past the end of the
			 * requested size, skip it completely.
			 */
			e820.nr_map = i;
		} else {
			e820.nr_map = i + 1;
			e820.map[i].size -= current_addr - size;
		}
		e820_print_map("limit_regions endfor");
		return;
	}
	e820_print_map("limit_regions endfunc");
}

/* Overridden in paravirt.c if CONFIG_PARAVIRT */
char * __init __attribute__((weak)) memory_setup(void)
{
	return machine_specific_memory_setup();
}

void __init setup_memory_map(void)
{
	printk(KERN_INFO "BIOS-provided physical RAM map:\n");
	e820_print_map(memory_setup());
}

static int __initdata user_defined_memmap;

/*
 * "mem=nopentium" disables the 4MB page tables.
 * "mem=XXX[kKmM]" defines a memory region from HIGH_MEM
 * to <mem>, overriding the bios size.
 * "memmap=XXX[KkmM]@XXX[KkmM]" defines a memory region from
 * <start> to <start>+<mem>, overriding the bios size.
 *
 * HPA tells me bootloaders need to parse mem=, so no new
 * option should be mem=  [also see Documentation/i386/boot.txt]
 */
static int __init parse_mem(char *arg)
{
	if (!arg)
		return -EINVAL;

	if (strcmp(arg, "nopentium") == 0) {
		setup_clear_cpu_cap(X86_FEATURE_PSE);
	} else {
		/* If the user specifies memory size, we
		 * limit the BIOS-provided memory map to
		 * that size. exactmap can be used to specify
		 * the exact map. mem=number can be used to
		 * trim the existing memory map.
		 */
		unsigned long long mem_size;

		mem_size = memparse(arg, &arg);
		limit_regions(mem_size);
		user_defined_memmap = 1;
	}
	return 0;
}
early_param("mem", parse_mem);

static int __init parse_memmap(char *arg)
{
	if (!arg)
		return -EINVAL;

	if (strcmp(arg, "exactmap") == 0) {
#ifdef CONFIG_CRASH_DUMP
		/* If we are doing a crash dump, we
		 * still need to know the real mem
		 * size before original memory map is
		 * reset.
		 */
		find_max_pfn();
		saved_max_pfn = max_pfn;
#endif
		e820.nr_map = 0;
		user_defined_memmap = 1;
	} else {
		/* If the user specifies memory size, we
		 * limit the BIOS-provided memory map to
		 * that size. exactmap can be used to specify
		 * the exact map. mem=number can be used to
		 * trim the existing memory map.
		 */
		unsigned long long start_at, mem_size;

		mem_size = memparse(arg, &arg);
		if (*arg == '@') {
			start_at = memparse(arg+1, &arg);
			add_memory_region(start_at, mem_size, E820_RAM);
		} else if (*arg == '#') {
			start_at = memparse(arg+1, &arg);
			add_memory_region(start_at, mem_size, E820_ACPI);
		} else if (*arg == '$') {
			start_at = memparse(arg+1, &arg);
			add_memory_region(start_at, mem_size, E820_RESERVED);
		} else {
			limit_regions(mem_size);
			user_defined_memmap = 1;
		}
	}
	return 0;
}
early_param("memmap", parse_memmap);

void __init finish_e820_parsing(void)
{
	if (user_defined_memmap) {
		printk(KERN_INFO "user-defined physical RAM map:\n");
		e820_print_map("user");
	}
}