/arch/i386/pci/mmconfig.c

  1/*
  2 * Copyright (C) 2004 Matthew Wilcox <matthew@wil.cx>
  3 * Copyright (C) 2004 Intel Corp.
  4 *
  5 * This code is released under the GNU General Public License version 2.
  6 */
  7
  8/*
  9 * mmconfig.c - Low-level direct PCI config space access via MMCONFIG
 10 */
 11
 12#include <linux/pci.h>
 13#include <linux/init.h>
 14#include "pci.h"
 15
 16/* The physical address of the MMCONFIG aperture.  Set from ACPI tables. */
 17u32 pci_mmcfg_base_addr;
 18
 19#define mmcfg_virt_addr ((void __iomem *) fix_to_virt(FIX_PCIE_MCFG))
 20
 21/* The base address of the last MMCONFIG device accessed */
 22static u32 mmcfg_last_accessed_device;
 23
 24/*
 25 * Functions for accessing PCI configuration space with MMCONFIG accesses
 26 */
 27
 28static inline void pci_exp_set_dev_base(int bus, int devfn)
 29{
 30	u32 dev_base = pci_mmcfg_base_addr | (bus << 20) | (devfn << 12);
 31	if (dev_base != mmcfg_last_accessed_device) {
 32		mmcfg_last_accessed_device = dev_base;
 33		set_fixmap_nocache(FIX_PCIE_MCFG, dev_base);
 34	}
 35}
 36
 37static int pci_mmcfg_read(unsigned int seg, unsigned int bus,
 38			  unsigned int devfn, int reg, int len, u32 *value)
 39{
 40	unsigned long flags;
 41
 42	if (!value || (bus > 255) || (devfn > 255) || (reg > 4095))
 43		return -EINVAL;
 44
 45	spin_lock_irqsave(&pci_config_lock, flags);
 46
 47	pci_exp_set_dev_base(bus, devfn);
 48
 49	switch (len) {
 50	case 1:
 51		*value = readb(mmcfg_virt_addr + reg);
 52		break;
 53	case 2:
 54		*value = readw(mmcfg_virt_addr + reg);
 55		break;
 56	case 4:
 57		*value = readl(mmcfg_virt_addr + reg);
 58		break;
 59	}
 60
 61	spin_unlock_irqrestore(&pci_config_lock, flags);
 62
 63	return 0;
 64}
 65
 66static int pci_mmcfg_write(unsigned int seg, unsigned int bus,
 67			   unsigned int devfn, int reg, int len, u32 value)
 68{
 69	unsigned long flags;
 70
 71	if ((bus > 255) || (devfn > 255) || (reg > 4095)) 
 72		return -EINVAL;
 73
 74	spin_lock_irqsave(&pci_config_lock, flags);
 75
 76	pci_exp_set_dev_base(bus, devfn);
 77
 78	switch (len) {
 79	case 1:
 80		writeb(value, mmcfg_virt_addr + reg);
 81		break;
 82	case 2:
 83		writew(value, mmcfg_virt_addr + reg);
 84		break;
 85	case 4:
 86		writel(value, mmcfg_virt_addr + reg);
 87		break;
 88	}
 89
 90	spin_unlock_irqrestore(&pci_config_lock, flags);
 91
 92	return 0;
 93}
 94
 95static struct pci_raw_ops pci_mmcfg = {
 96	.read =		pci_mmcfg_read,
 97	.write =	pci_mmcfg_write,
 98};
 99
100static int __init pci_mmcfg_init(void)
101{
102	if ((pci_probe & PCI_PROBE_MMCONF) == 0)
103		goto out;
104	if (!pci_mmcfg_base_addr)
105		goto out;
106
107	/* Kludge for now. Don't use mmconfig on AMD systems because
108	   those have some busses where mmconfig doesn't work,
109	   and we don't parse ACPI MCFG well enough to handle that. 
110	   Remove when proper handling is added. */
111	if (boot_cpu_data.x86_vendor == X86_VENDOR_AMD)
112		goto out; 
113
114	printk(KERN_INFO "PCI: Using MMCONFIG\n");
115	raw_pci_ops = &pci_mmcfg;
116	pci_probe = (pci_probe & ~PCI_PROBE_MASK) | PCI_PROBE_MMCONF;
117
118 out:
119	return 0;
120}
121
122arch_initcall(pci_mmcfg_init);