/*
 * mmconfig.c - Low-level direct PCI config space access via MMCONFIG
 * 
 * This is an 64bit optimized version that always keeps the full mmconfig
 * space mapped. This allows lockless config space operation.
 */

#include <linux/pci.h>
#include <linux/init.h>
#include "pci.h"

#define MMCONFIG_APER_SIZE (256*1024*1024)

/* The physical address of the MMCONFIG aperture.  Set from ACPI tables. */
u32 pci_mmcfg_base_addr;

/* Static virtual mapping of the MMCONFIG aperture */
char *pci_mmcfg_virt;

static inline char *pci_dev_base(int bus, int devfn)
{
	return pci_mmcfg_virt + ((bus << 20) | (devfn << 12));
}

static int pci_mmcfg_read(int seg, int bus, int devfn, int reg, int len, u32 *value)
{
	char *addr = pci_dev_base(bus, devfn); 

	if (unlikely(!value || (bus > 255) || (devfn > 255) || (reg > 4095)))
		return -EINVAL;

	switch (len) {
	case 1:
		*value = readb(addr + reg);
		break;
	case 2:
		*value = readw(addr + reg);
		break;
	case 4:
		*value = readl(addr + reg);
		break;
	}

	return 0;
}

static int pci_mmcfg_write(int seg, int bus, int devfn, int reg, int len, u32 value)
{
	char *addr = pci_dev_base(bus,devfn);

	if (unlikely((bus > 255) || (devfn > 255) || (reg > 4095)))
		return -EINVAL;

	switch (len) {
	case 1:
		writeb(value, addr + reg);
		break;
	case 2:
		writew(value, addr + reg);
		break;
	case 4:
		writel(value, addr + reg);
		break;
	}

	/* Dummy read to flush PCI write */
	readl(addr);

	return 0;
}

static struct pci_raw_ops pci_mmcfg = {
	.read =		pci_mmcfg_read,
	.write =	pci_mmcfg_write,
};

static int __init pci_mmcfg_init(void)
{
	if ((pci_probe & PCI_PROBE_MMCONF) == 0)
		return 0;
	if (!pci_mmcfg_base_addr)
		return 0;

	/* RED-PEN i386 doesn't do _nocache right now */
	pci_mmcfg_virt = ioremap_nocache(pci_mmcfg_base_addr, MMCONFIG_APER_SIZE);
	if (!pci_mmcfg_virt) { 
		printk("PCI: Cannot map mmconfig aperture\n");
		return 0;
	}	

	printk(KERN_INFO "PCI: Using MMCONFIG at %x\n", pci_mmcfg_base_addr);
	raw_pci_ops = &pci_mmcfg;
	pci_probe = (pci_probe & ~PCI_PROBE_MASK) | PCI_PROBE_MMCONF;

	return 0;
}

arch_initcall(pci_mmcfg_init);