arch/x86_64/pci/mmconfig.c

   1 /*
   2  * mmconfig.c - Low-level direct PCI config space access via MMCONFIG
   3  *
   4  * This is an 64bit optimized version that always keeps the full mmconfig
   5  * space mapped. This allows lockless config space operation.
   6  */
   7
   8 #include <linux/pci.h>
   9 #include <linux/init.h>
  10 #include <linux/acpi.h>
  11 #include <linux/bitmap.h>
  12 #include "pci.h"
  13
  14 #define MMCONFIG_APER_SIZE (256*1024*1024)
  15
  16 static DECLARE_BITMAP(fallback_slots, 32);
  17
  18 /* Static virtual mapping of the MMCONFIG aperture */
  19 struct mmcfg_virt {
  20         struct acpi_table_mcfg_config *cfg;
  21         char __iomem *virt;
  22 };
  23 static struct mmcfg_virt *pci_mmcfg_virt;
  24
  25 static char __iomem *get_virt(unsigned int seg, unsigned 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                         /* Not found - fall back to type 1. This happens
  34                            e.g. on the internal devices of a K8 northbridge. */
  35                         return NULL;
  36                 }
  37                 cfg = pci_mmcfg_virt[cfg_num].cfg;
  38                 if (cfg->pci_segment_group_number != seg)
  39                         continue;
  40                 if ((cfg->start_bus_number <= bus) &&
  41                     (cfg->end_bus_number >= bus))
  42                         return pci_mmcfg_virt[cfg_num].virt;
  43         }
  44 }
  45
  46 static char __iomem *pci_dev_base(unsigned int seg, unsigned int bus, unsigned int devfn)
  47 {
  48         char __iomem *addr;
  49         if (seg == 0 && bus == 0 && test_bit(PCI_SLOT(devfn), &fallback_slots))
  50                 return NULL;
  51         addr = get_virt(seg, bus);
  52         if (!addr)
  53                 return NULL;
  54         return addr + ((bus << 20) | (devfn << 12));
  55 }
  56
  57 static int pci_mmcfg_read(unsigned int seg, unsigned int bus,
  58                           unsigned int devfn, int reg, int len, u32 *value)
  59 {
  60         char __iomem *addr;
  61
  62         /* Why do we have this when nobody checks it. How about a BUG()!? -AK */
  63         if (unlikely(!value || (bus > 255) || (devfn > 255) || (reg > 4095)))
  64                 return -EINVAL;
  65
  66         addr = pci_dev_base(seg, bus, devfn);
  67         if (!addr)
  68                 return pci_conf1_read(seg,bus,devfn,reg,len,value);
  69
  70         switch (len) {
  71         case 1:
  72                 *value = readb(addr + reg);
  73                 break;
  74         case 2:
  75                 *value = readw(addr + reg);
  76                 break;
  77         case 4:
  78                 *value = readl(addr + reg);
  79                 break;
  80         }
  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         char __iomem *addr;
  89
  90         /* Why do we have this when nobody checks it. How about a BUG()!? -AK */
  91         if (unlikely((bus > 255) || (devfn > 255) || (reg > 4095)))
  92                 return -EINVAL;
  93
  94         addr = pci_dev_base(seg, bus, devfn);
  95         if (!addr)
  96                 return pci_conf1_write(seg,bus,devfn,reg,len,value);
  97
  98         switch (len) {
  99         case 1:
 100                 writeb(value, addr + reg);
 101                 break;
 102         case 2:
 103                 writew(value, addr + reg);
 104                 break;
 105         case 4:
 106                 writel(value, addr + reg);
 107                 break;
 108         }
 109
 110         return 0;
 111 }
 112
 113 static struct pci_raw_ops pci_mmcfg = {
 114         .read =         pci_mmcfg_read,
 115         .write =        pci_mmcfg_write,
 116 };
 117
 118 /* K8 systems have some devices (typically in the builtin northbridge)
 119    that are only accessible using type1
 120    Normally this can be expressed in the MCFG by not listing them
 121    and assigning suitable _SEGs, but this isn't implemented in some BIOS.
 122    Instead try to discover all devices on bus 0 that are unreachable using MM
 123    and fallback for them.
 124    We only do this for bus 0/seg 0 */
 125 static __init void unreachable_devices(void)
 126 {
 127         int i;
 128         for (i = 0; i < 32; i++) {
 129                 u32 val1;
 130                 char __iomem *addr;
 131
 132                 pci_conf1_read(0, 0, PCI_DEVFN(i,0), 0, 4, &val1);
 133                 if (val1 == 0xffffffff)
 134                         continue;
 135                 addr = pci_dev_base(0, 0, PCI_DEVFN(i, 0));
 136                 if (addr == NULL|| readl(addr) != val1) {
 137                         set_bit(i, &fallback_slots);
 138                 }
 139         }
 140 }
 141
 142 static int __init pci_mmcfg_init(void)
 143 {
 144         int i;
 145
 146         if ((pci_probe & PCI_PROBE_MMCONF) == 0)
 147                 return 0;
 148
 149         acpi_table_parse(ACPI_MCFG, acpi_parse_mcfg);
 150         if ((pci_mmcfg_config_num == 0) ||
 151             (pci_mmcfg_config == NULL) ||
 152             (pci_mmcfg_config[0].base_address == 0))
 153                 return 0;
 154
 155         /* RED-PEN i386 doesn't do _nocache right now */
 156         pci_mmcfg_virt = kmalloc(sizeof(*pci_mmcfg_virt) * pci_mmcfg_config_num, GFP_KERNEL);
 157         if (pci_mmcfg_virt == NULL) {
 158                 printk("PCI: Can not allocate memory for mmconfig structures\n");
 159                 return 0;
 160         }
 161         for (i = 0; i < pci_mmcfg_config_num; ++i) {
 162                 pci_mmcfg_virt[i].cfg = &pci_mmcfg_config[i];
 163                 pci_mmcfg_virt[i].virt = ioremap_nocache(pci_mmcfg_config[i].base_address, MMCONFIG_APER_SIZE);
 164                 if (!pci_mmcfg_virt[i].virt) {
 165                         printk("PCI: Cannot map mmconfig aperture for segment %d\n",
 166                                pci_mmcfg_config[i].pci_segment_group_number);
 167                         return 0;
 168                 }
 169                 printk(KERN_INFO "PCI: Using MMCONFIG at %x\n", pci_mmcfg_config[i].base_address);
 170         }
 171
 172         unreachable_devices();
 173
 174         raw_pci_ops = &pci_mmcfg;
 175         pci_probe = (pci_probe & ~PCI_PROBE_MASK) | PCI_PROBE_MMCONF;
 176
 177         return 0;
 178 }
 179
 180 arch_initcall(pci_mmcfg_init);