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 <asm/e820.h>
  13
  14 #include "pci.h"
  15
  16 /* aperture is up to 256MB but BIOS may reserve less */
  17 #define MMCONFIG_APER_MIN       (2 * 1024*1024)
  18 #define MMCONFIG_APER_MAX       (256 * 1024*1024)
  19
  20 /* Verify the first 16 busses. We assume that systems with more busses
  21    get MCFG right. */
  22 #define MAX_CHECK_BUS 16
  23
  24 static DECLARE_BITMAP(fallback_slots, 32*MAX_CHECK_BUS);
  25
  26 /* Static virtual mapping of the MMCONFIG aperture */
  27 struct mmcfg_virt {
  28         struct acpi_table_mcfg_config *cfg;
  29         char __iomem *virt;
  30 };
  31 static struct mmcfg_virt *pci_mmcfg_virt;
  32
  33 static char __iomem *get_virt(unsigned int seg, unsigned bus)
  34 {
  35         int cfg_num = -1;
  36         struct acpi_table_mcfg_config *cfg;
  37
  38         while (1) {
  39                 ++cfg_num;
  40                 if (cfg_num >= pci_mmcfg_config_num)
  41                         break;
  42                 cfg = pci_mmcfg_virt[cfg_num].cfg;
  43                 if (cfg->pci_segment_group_number != seg)
  44                         continue;
  45                 if ((cfg->start_bus_number <= bus) &&
  46                     (cfg->end_bus_number >= bus))
  47                         return pci_mmcfg_virt[cfg_num].virt;
  48         }
  49
  50         /* Handle more broken MCFG tables on Asus etc.
  51            They only contain a single entry for bus 0-0. Assume
  52            this applies to all busses. */
  53         cfg = &pci_mmcfg_config[0];
  54         if (pci_mmcfg_config_num == 1 &&
  55                 cfg->pci_segment_group_number == 0 &&
  56                 (cfg->start_bus_number | cfg->end_bus_number) == 0)
  57                 return pci_mmcfg_virt[0].virt;
  58
  59         /* Fall back to type 0 */
  60         return NULL;
  61 }
  62
  63 static char __iomem *pci_dev_base(unsigned int seg, unsigned int bus, unsigned int devfn)
  64 {
  65         char __iomem *addr;
  66         if (seg == 0 && bus < MAX_CHECK_BUS &&
  67                 test_bit(32*bus + PCI_SLOT(devfn), fallback_slots))
  68                 return NULL;
  69         addr = get_virt(seg, bus);
  70         if (!addr)
  71                 return NULL;
  72         return addr + ((bus << 20) | (devfn << 12));
  73 }
  74
  75 static int pci_mmcfg_read(unsigned int seg, unsigned int bus,
  76                           unsigned int devfn, int reg, int len, u32 *value)
  77 {
  78         char __iomem *addr;
  79
  80         /* Why do we have this when nobody checks it. How about a BUG()!? -AK */
  81         if (unlikely((bus > 255) || (devfn > 255) || (reg > 4095))) {
  82                 *value = -1;
  83                 return -EINVAL;
  84         }
  85
  86         addr = pci_dev_base(seg, bus, devfn);
  87         if (!addr)
  88                 return pci_conf1_read(seg,bus,devfn,reg,len,value);
  89
  90         switch (len) {
  91         case 1:
  92                 *value = readb(addr + reg);
  93                 break;
  94         case 2:
  95                 *value = readw(addr + reg);
  96                 break;
  97         case 4:
  98                 *value = readl(addr + reg);
  99                 break;
 100         }
 101
 102         return 0;
 103 }
 104
 105 static int pci_mmcfg_write(unsigned int seg, unsigned int bus,
 106                            unsigned int devfn, int reg, int len, u32 value)
 107 {
 108         char __iomem *addr;
 109
 110         /* Why do we have this when nobody checks it. How about a BUG()!? -AK */
 111         if (unlikely((bus > 255) || (devfn > 255) || (reg > 4095)))
 112                 return -EINVAL;
 113
 114         addr = pci_dev_base(seg, bus, devfn);
 115         if (!addr)
 116                 return pci_conf1_write(seg,bus,devfn,reg,len,value);
 117
 118         switch (len) {
 119         case 1:
 120                 writeb(value, addr + reg);
 121                 break;
 122         case 2:
 123                 writew(value, addr + reg);
 124                 break;
 125         case 4:
 126                 writel(value, addr + reg);
 127                 break;
 128         }
 129
 130         return 0;
 131 }
 132
 133 static struct pci_raw_ops pci_mmcfg = {
 134         .read =         pci_mmcfg_read,
 135         .write =        pci_mmcfg_write,
 136 };
 137
 138 /* K8 systems have some devices (typically in the builtin northbridge)
 139    that are only accessible using type1
 140    Normally this can be expressed in the MCFG by not listing them
 141    and assigning suitable _SEGs, but this isn't implemented in some BIOS.
 142    Instead try to discover all devices on bus 0 that are unreachable using MM
 143    and fallback for them. */
 144 static __init void unreachable_devices(void)
 145 {
 146         int i, k;
 147         /* Use the max bus number from ACPI here? */
 148         for (k = 0; k < MAX_CHECK_BUS; k++) {
 149                 for (i = 0; i < 32; i++) {
 150                         u32 val1;
 151                         char __iomem *addr;
 152
 153                         pci_conf1_read(0, k, PCI_DEVFN(i,0), 0, 4, &val1);
 154                         if (val1 == 0xffffffff)
 155                                 continue;
 156                         addr = pci_dev_base(0, k, PCI_DEVFN(i, 0));
 157                         if (addr == NULL|| readl(addr) != val1) {
 158                                 set_bit(i + 32*k, fallback_slots);
 159                                 printk(KERN_NOTICE "PCI: No mmconfig possible"
 160                                        " on device %02x:%02x\n", k, i);
 161                         }
 162                 }
 163         }
 164 }
 165
 166 void __init pci_mmcfg_init(int type)
 167 {
 168         int i;
 169
 170         if ((pci_probe & PCI_PROBE_MMCONF) == 0)
 171                 return;
 172
 173         acpi_table_parse(ACPI_MCFG, acpi_parse_mcfg);
 174         if ((pci_mmcfg_config_num == 0) ||
 175             (pci_mmcfg_config == NULL) ||
 176             (pci_mmcfg_config[0].base_address == 0))
 177                 return;
 178
 179         /* Only do this check when type 1 works. If it doesn't work
 180            assume we run on a Mac and always use MCFG */
 181         if (type == 1 && !e820_all_mapped(pci_mmcfg_config[0].base_address,
 182                         pci_mmcfg_config[0].base_address + MMCONFIG_APER_MIN,
 183                         E820_RESERVED)) {
 184                 printk(KERN_ERR "PCI: BIOS Bug: MCFG area at %x is not E820-reserved\n",
 185                                 pci_mmcfg_config[0].base_address);
 186                 printk(KERN_ERR "PCI: Not using MMCONFIG.\n");
 187                 return;
 188         }
 189
 190         pci_mmcfg_virt = kmalloc(sizeof(*pci_mmcfg_virt) * pci_mmcfg_config_num, GFP_KERNEL);
 191         if (pci_mmcfg_virt == NULL) {
 192                 printk(KERN_ERR "PCI: Can not allocate memory for mmconfig structures\n");
 193                 return;
 194         }
 195         for (i = 0; i < pci_mmcfg_config_num; ++i) {
 196                 pci_mmcfg_virt[i].cfg = &pci_mmcfg_config[i];
 197                 pci_mmcfg_virt[i].virt = ioremap_nocache(pci_mmcfg_config[i].base_address,
 198                                                          MMCONFIG_APER_MAX);
 199                 if (!pci_mmcfg_virt[i].virt) {
 200                         printk(KERN_ERR "PCI: Cannot map mmconfig aperture for "
 201                                         "segment %d\n",
 202                                pci_mmcfg_config[i].pci_segment_group_number);
 203                         return;
 204                 }
 205                 printk(KERN_INFO "PCI: Using MMCONFIG at %x\n", pci_mmcfg_config[i].base_address);
 206         }
 207
 208         unreachable_devices();
 209
 210         raw_pci_ops = &pci_mmcfg;
 211         pci_probe = (pci_probe & ~PCI_PROBE_MASK) | PCI_PROBE_MMCONF;
 212 }