/*
   * 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 <linux/bitmap.h>

  #include <asm/e820.h>

  #include <asm/pci_x86.h>

  #define PREFIX "PCI: "

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

  {

  	struct pci_mmcfg_region *cfg = pci_mmconfig_lookup(seg, bus);

  	if (cfg && cfg->virt)
  		return cfg->virt + (PCI_MMCFG_BUS_OFFSET(bus) | (devfn << 12));
  	return NULL;

  }
  
  static int pci_mmcfg_read(unsigned int seg, unsigned int bus,
  			  unsigned int devfn, int reg, int len, u32 *value)
  {

  	char __iomem *addr;

  	/* Why do we have this when nobody checks it. How about a BUG()!? -AK */

  	if (unlikely((bus > 255) || (devfn > 255) || (reg > 4095))) {

  err:		*value = -1;

  		return -EINVAL;

  	}

  	addr = pci_dev_base(seg, bus, devfn);
  	if (!addr)

  		goto err;

  	switch (len) {
  	case 1:

  		*value = mmio_config_readb(addr + reg);

  		break;
  	case 2:

  		*value = mmio_config_readw(addr + reg);

  		break;
  	case 4:

  		*value = mmio_config_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 __iomem *addr;

  	/* Why do we have this when nobody checks it. How about a BUG()!? -AK */

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

  	addr = pci_dev_base(seg, bus, devfn);
  	if (!addr)

  		return -EINVAL;

  	switch (len) {
  	case 1:

  		mmio_config_writeb(addr + reg, value);

  		break;
  	case 2:

  		mmio_config_writew(addr + reg, value);

  		break;
  	case 4:

  		mmio_config_writel(addr + reg, value);

  		break;
  	}
  
  	return 0;
  }

  static const struct pci_raw_ops pci_mmcfg = {

  	.read =		pci_mmcfg_read,
  	.write =	pci_mmcfg_write,
  };

  static void __iomem * __init mcfg_ioremap(struct pci_mmcfg_region *cfg)

  {
  	void __iomem *addr;

  	u64 start, size;

  	int num_buses;

  	start = cfg->address + PCI_MMCFG_BUS_OFFSET(cfg->start_bus);
  	num_buses = cfg->end_bus - cfg->start_bus + 1;

  	size = PCI_MMCFG_BUS_OFFSET(num_buses);

  	addr = ioremap_nocache(start, size);

  	if (addr)

  		addr -= PCI_MMCFG_BUS_OFFSET(cfg->start_bus);

  	return addr;
  }

  int __init pci_mmcfg_arch_init(void)

  {

  	struct pci_mmcfg_region *cfg;

  	list_for_each_entry(cfg, &pci_mmcfg_list, list) {

  		cfg->virt = mcfg_ioremap(cfg);
  		if (!cfg->virt) {

  			printk(KERN_ERR PREFIX "can't map MMCONFIG at %pR
  ",
  			       &cfg->res);

  			pci_mmcfg_arch_free();

  			return 0;

  		}

  	}

  	raw_pci_ext_ops = &pci_mmcfg;

  	return 1;

  }

  
  void __init pci_mmcfg_arch_free(void)
  {

  	struct pci_mmcfg_region *cfg;

  	list_for_each_entry(cfg, &pci_mmcfg_list, list) {

  		if (cfg->virt) {
  			iounmap(cfg->virt + PCI_MMCFG_BUS_OFFSET(cfg->start_bus));
  			cfg->virt = NULL;

  		}
  	}

  }