early.c

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#include <linux/kernel.h>
#include <linux/pci.h>
#include <asm/pci-direct.h>
#include <asm/io.h>
#include <asm/pci_x86.h>

/* Direct PCI access. This is used for PCI accesses in early boot before
   the PCI subsystem works. */

u32 read_pci_config(u8 bus, u8 slot, u8 func, u8 offset)
{
    u32 v;
    outl(0x80000000 | (bus<<16) | (slot<<11) | (func<<8) | offset, 0xcf8);
    v = inl(0xcfc);
    return v;
}

u8 read_pci_config_byte(u8 bus, u8 slot, u8 func, u8 offset)
{
    u8 v;
    outl(0x80000000 | (bus<<16) | (slot<<11) | (func<<8) | offset, 0xcf8);
    v = inb(0xcfc + (offset&3));
    return v;
}

u16 read_pci_config_16(u8 bus, u8 slot, u8 func, u8 offset)
{
    u16 v;
    outl(0x80000000 | (bus<<16) | (slot<<11) | (func<<8) | offset, 0xcf8);
    v = inw(0xcfc + (offset&2));
    return v;
}

void write_pci_config(u8 bus, u8 slot, u8 func, u8 offset,
                    u32 val)
{
    outl(0x80000000 | (bus<<16) | (slot<<11) | (func<<8) | offset, 0xcf8);
    outl(val, 0xcfc);
}

void write_pci_config_byte(u8 bus, u8 slot, u8 func, u8 offset, u8 val)
{
    outl(0x80000000 | (bus<<16) | (slot<<11) | (func<<8) | offset, 0xcf8);
    outb(val, 0xcfc + (offset&3));
}

void write_pci_config_16(u8 bus, u8 slot, u8 func, u8 offset, u16 val)
{
    outl(0x80000000 | (bus<<16) | (slot<<11) | (func<<8) | offset, 0xcf8);
    outw(val, 0xcfc + (offset&2));
}

int early_pci_allowed(void)
{
    return (pci_probe & (PCI_PROBE_CONF1|PCI_PROBE_NOEARLY)) ==
            PCI_PROBE_CONF1;
}

void early_dump_pci_device(u8 bus, u8 slot, u8 func)
{
    int i;
    int j;
    u32 val;

    printk(KERN_INFO "pci 0000:%02x:%02x.%d config space:",
           bus, slot, func);

    for (i = 0; i < 256; i += 4) {
        if (!(i & 0x0f))
            printk("\n  %02x:",i);

        val = read_pci_config(bus, slot, func, i);
        for (j = 0; j < 4; j++) {
            printk(" %02x", val & 0xff);
            val >>= 8;
        }
    }
    printk("\n");
}

void early_dump_pci_devices(void)
{
    unsigned bus, slot, func;

    if (!early_pci_allowed())
        return;

    for (bus = 0; bus < 256; bus++) {
        for (slot = 0; slot < 32; slot++) {
            for (func = 0; func < 8; func++) {
                u32 class;
                u8 type;

                class = read_pci_config(bus, slot, func,
                            PCI_CLASS_REVISION);
                if (class == 0xffffffff)
                    continue;

                early_dump_pci_device(bus, slot, func);

                if (func == 0) {
                    type = read_pci_config_byte(bus, slot,
                                    func,
                                   PCI_HEADER_TYPE);
                    if (!(type & 0x80))
                        break;
                }
            }
        }
    }
}