root/arch/x86/kernel/probe_roms_32.c

DEFINITIONS

1. romsignature
2. romchecksum
3. probe_roms

#include <linux/sched.h>
#include <linux/mm.h>
#include <linux/uaccess.h>
#include <linux/mmzone.h>
#include <linux/ioport.h>
#include <linux/seq_file.h>
#include <linux/console.h>
#include <linux/init.h>
#include <linux/edd.h>
#include <linux/dmi.h>
#include <linux/pfn.h>
#include <linux/pci.h>
#include <asm/pci-direct.h>


#include <asm/e820.h>
#include <asm/mmzone.h>
#include <asm/setup.h>
#include <asm/sections.h>
#include <asm/io.h>
#include <setup_arch.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;
}

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;
        }
}