/*
 * 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 <linux/acpi.h>
#include "pci.h"

#define MMCONFIG_APER_SIZE (256*1024*1024)

/* Static virtual mapping of the MMCONFIG aperture */
struct mmcfg_virt {
	struct acpi_table_mcfg_config *cfg;
	char *virt;
};
static struct mmcfg_virt *pci_mmcfg_virt;

static char *get_virt(unsigned int seg, int bus)
{
	int cfg_num = -1;
	struct acpi_table_mcfg_config *cfg;

	while (1) {
		++cfg_num;
		if (cfg_num >= pci_mmcfg_config_num) {
			/* something bad is going on, no cfg table is found. */
			/* so we fall back to the old way we used to do this */
			/* and just rely on the first entry to be correct. */
			return pci_mmcfg_virt[0].virt;
		}
		cfg = pci_mmcfg_virt[cfg_num].cfg;
		if (cfg->pci_segment_group_number != seg)
			continue;
		if ((cfg->start_bus_number <= bus) &&
		    (cfg->end_bus_number >= bus))
			return pci_mmcfg_virt[cfg_num].virt;
	}
}

static inline char *pci_dev_base(unsigned int seg, unsigned int bus, unsigned int devfn)
{

	return get_virt(seg, bus) + ((bus << 20) | (devfn << 12));
}

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

	return 0;
}

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

static int __init pci_mmcfg_init(void)
{
	int i;

	if ((pci_probe & PCI_PROBE_MMCONF) == 0)
		return 0;

	acpi_table_parse(ACPI_MCFG, acpi_parse_mcfg);
	if ((pci_mmcfg_config_num == 0) ||
	    (pci_mmcfg_config == NULL) ||
	    (pci_mmcfg_config[0].base_address == 0))
		return 0;

	/* Kludge for now. Don't use mmconfig on AMD systems because
	   those have some busses where mmconfig doesn't work,
	   and we don't parse ACPI MCFG well enough to handle that. 
	   Remove when proper handling is added. */
	if (boot_cpu_data.x86_vendor == X86_VENDOR_AMD)
		return 0; 

	/* RED-PEN i386 doesn't do _nocache right now */
	pci_mmcfg_virt = kmalloc(sizeof(*pci_mmcfg_virt) * pci_mmcfg_config_num, GFP_KERNEL);
	if (pci_mmcfg_virt == NULL) {
		printk("PCI: Can not allocate memory for mmconfig structures\n");
		return 0;
	}
	for (i = 0; i < pci_mmcfg_config_num; ++i) {
		pci_mmcfg_virt[i].cfg = &pci_mmcfg_config[i];
		pci_mmcfg_virt[i].virt = ioremap_nocache(pci_mmcfg_config[i].base_address, MMCONFIG_APER_SIZE);
		if (!pci_mmcfg_virt[i].virt) {
			printk("PCI: Cannot map mmconfig aperture for segment %d\n",
			       pci_mmcfg_config[i].pci_segment_group_number);
			return 0;
		}
		printk(KERN_INFO "PCI: Using MMCONFIG at %x\n", pci_mmcfg_config[i].base_address);
	}

	raw_pci_ops = &pci_mmcfg;
	pci_probe = (pci_probe & ~PCI_PROBE_MASK) | PCI_PROBE_MMCONF;

	return 0;
}

arch_initcall(pci_mmcfg_init);