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 <linux/acpi.h>
  15 #include "pci.h"
  16
  17 #define mmcfg_virt_addr ((void __iomem *) fix_to_virt(FIX_PCIE_MCFG))
  18
  19 /* The base address of the last MMCONFIG device accessed */
  20 static u32 mmcfg_last_accessed_device;
  21
  22 /*
  23  * Functions for accessing PCI configuration space with MMCONFIG accesses
  24  */
  25 static u32 get_base_addr(unsigned int seg, int bus)
  26 {
  27         int cfg_num = -1;
  28         struct acpi_table_mcfg_config *cfg;
  29
  30         while (1) {
  31                 ++cfg_num;
  32                 if (cfg_num >= pci_mmcfg_config_num) {
  33                         /* something bad is going on, no cfg table is found. */
  34                         /* so we fall back to the old way we used to do this */
  35                         /* and just rely on the first entry to be correct. */
  36                         return pci_mmcfg_config[0].base_address;
  37                 }
  38                 cfg = &pci_mmcfg_config[cfg_num];
  39                 if (cfg->pci_segment_group_number != seg)
  40                         continue;
  41                 if ((cfg->start_bus_number <= bus) &&
  42                     (cfg->end_bus_number >= bus))
  43                         return cfg->base_address;
  44         }
  45 }
  46
  47 static inline void pci_exp_set_dev_base(unsigned int seg, int bus, int devfn)
  48 {
  49         u32 dev_base = get_base_addr(seg, bus) | (bus << 20) | (devfn << 12);
  50         if (dev_base != mmcfg_last_accessed_device) {
  51                 mmcfg_last_accessed_device = dev_base;
  52                 set_fixmap_nocache(FIX_PCIE_MCFG, dev_base);
  53         }
  54 }
  55
  56 static int pci_mmcfg_read(unsigned int seg, unsigned int bus,
  57                           unsigned int devfn, int reg, int len, u32 *value)
  58 {
  59         unsigned long flags;
  60
  61         if (!value || (bus > 255) || (devfn > 255) || (reg > 4095))
  62                 return -EINVAL;
  63
  64         spin_lock_irqsave(&pci_config_lock, flags);
  65
  66         pci_exp_set_dev_base(seg, bus, devfn);
  67
  68         switch (len) {
  69         case 1:
  70                 *value = readb(mmcfg_virt_addr + reg);
  71                 break;
  72         case 2:
  73                 *value = readw(mmcfg_virt_addr + reg);
  74                 break;
  75         case 4:
  76                 *value = readl(mmcfg_virt_addr + reg);
  77                 break;
  78         }
  79
  80         spin_unlock_irqrestore(&pci_config_lock, flags);
  81
  82         return 0;
  83 }
  84
  85 static int pci_mmcfg_write(unsigned int seg, unsigned int bus,
  86                            unsigned int devfn, int reg, int len, u32 value)
  87 {
  88         unsigned long flags;
  89
  90         if ((bus > 255) || (devfn > 255) || (reg > 4095))
  91                 return -EINVAL;
  92
  93         spin_lock_irqsave(&pci_config_lock, flags);
  94
  95         pci_exp_set_dev_base(seg, bus, devfn);
  96
  97         switch (len) {
  98         case 1:
  99                 writeb(value, mmcfg_virt_addr + reg);
 100                 break;
 101         case 2:
 102                 writew(value, mmcfg_virt_addr + reg);
 103                 break;
 104         case 4:
 105                 writel(value, mmcfg_virt_addr + reg);
 106                 break;
 107         }
 108
 109         spin_unlock_irqrestore(&pci_config_lock, flags);
 110
 111         return 0;
 112 }
 113
 114 static struct pci_raw_ops pci_mmcfg = {
 115         .read =         pci_mmcfg_read,
 116         .write =        pci_mmcfg_write,
 117 };
 118
 119 static int __init pci_mmcfg_init(void)
 120 {
 121         if ((pci_probe & PCI_PROBE_MMCONF) == 0)
 122                 goto out;
 123
 124         acpi_table_parse(ACPI_MCFG, acpi_parse_mcfg);
 125         if ((pci_mmcfg_config_num == 0) ||
 126             (pci_mmcfg_config == NULL) ||
 127             (pci_mmcfg_config[0].base_address == 0))
 128                 goto out;
 129
 130         printk(KERN_INFO "PCI: Using MMCONFIG\n");
 131         raw_pci_ops = &pci_mmcfg;
 132         pci_probe = (pci_probe & ~PCI_PROBE_MASK) | PCI_PROBE_MMCONF;
 133
 134  out:
 135         return 0;
 136 }
 137
 138 arch_initcall(pci_mmcfg_init);