arch/x86/pci/mmconfig_64.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 <linux/rcupdate.h>
  13 #include <asm/e820.h>
  14 #include <asm/pci_x86.h>
  15
  16 #define PREFIX "PCI: "
  17
  18 static char __iomem *pci_dev_base(unsigned int seg, unsigned int bus, unsigned int devfn)
  19 {
  20         struct pci_mmcfg_region *cfg = pci_mmconfig_lookup(seg, bus);
  21
  22         if (cfg && cfg->virt)
  23                 return cfg->virt + (PCI_MMCFG_BUS_OFFSET(bus) | (devfn << 12));
  24         return NULL;
  25 }
  26
  27 static int pci_mmcfg_read(unsigned int seg, unsigned int bus,
  28                           unsigned int devfn, int reg, int len, u32 *value)
  29 {
  30         char __iomem *addr;
  31
  32         /* Why do we have this when nobody checks it. How about a BUG()!? -AK */
  33         if (unlikely((bus > 255) || (devfn > 255) || (reg > 4095))) {
  34 err:            *value = -1;
  35                 return -EINVAL;
  36         }
  37
  38         rcu_read_lock();
  39         addr = pci_dev_base(seg, bus, devfn);
  40         if (!addr) {
  41                 rcu_read_unlock();
  42                 goto err;
  43         }
  44
  45         switch (len) {
  46         case 1:
  47                 *value = mmio_config_readb(addr + reg);
  48                 break;
  49         case 2:
  50                 *value = mmio_config_readw(addr + reg);
  51                 break;
  52         case 4:
  53                 *value = mmio_config_readl(addr + reg);
  54                 break;
  55         }
  56         rcu_read_unlock();
  57
  58         return 0;
  59 }
  60
  61 static int pci_mmcfg_write(unsigned int seg, unsigned int bus,
  62                            unsigned int devfn, int reg, int len, u32 value)
  63 {
  64         char __iomem *addr;
  65
  66         /* Why do we have this when nobody checks it. How about a BUG()!? -AK */
  67         if (unlikely((bus > 255) || (devfn > 255) || (reg > 4095)))
  68                 return -EINVAL;
  69
  70         rcu_read_lock();
  71         addr = pci_dev_base(seg, bus, devfn);
  72         if (!addr) {
  73                 rcu_read_unlock();
  74                 return -EINVAL;
  75         }
  76
  77         switch (len) {
  78         case 1:
  79                 mmio_config_writeb(addr + reg, value);
  80                 break;
  81         case 2:
  82                 mmio_config_writew(addr + reg, value);
  83                 break;
  84         case 4:
  85                 mmio_config_writel(addr + reg, value);
  86                 break;
  87         }
  88         rcu_read_unlock();
  89
  90         return 0;
  91 }
  92
  93 const struct pci_raw_ops pci_mmcfg = {
  94         .read =         pci_mmcfg_read,
  95         .write =        pci_mmcfg_write,
  96 };
  97
  98 static void __iomem *mcfg_ioremap(struct pci_mmcfg_region *cfg)
  99 {
 100         void __iomem *addr;
 101         u64 start, size;
 102         int num_buses;
 103
 104         start = cfg->address + PCI_MMCFG_BUS_OFFSET(cfg->start_bus);
 105         num_buses = cfg->end_bus - cfg->start_bus + 1;
 106         size = PCI_MMCFG_BUS_OFFSET(num_buses);
 107         addr = ioremap_nocache(start, size);
 108         if (addr)
 109                 addr -= PCI_MMCFG_BUS_OFFSET(cfg->start_bus);
 110         return addr;
 111 }
 112
 113 int __init pci_mmcfg_arch_init(void)
 114 {
 115         struct pci_mmcfg_region *cfg;
 116
 117         list_for_each_entry(cfg, &pci_mmcfg_list, list)
 118                 if (pci_mmcfg_arch_map(cfg)) {
 119                         pci_mmcfg_arch_free();
 120                         return 0;
 121                 }
 122
 123         raw_pci_ext_ops = &pci_mmcfg;
 124
 125         return 1;
 126 }
 127
 128 void __init pci_mmcfg_arch_free(void)
 129 {
 130         struct pci_mmcfg_region *cfg;
 131
 132         list_for_each_entry(cfg, &pci_mmcfg_list, list)
 133                 pci_mmcfg_arch_unmap(cfg);
 134 }
 135
 136 int pci_mmcfg_arch_map(struct pci_mmcfg_region *cfg)
 137 {
 138         cfg->virt = mcfg_ioremap(cfg);
 139         if (!cfg->virt) {
 140                 pr_err(PREFIX "can't map MMCONFIG at %pR\n", &cfg->res);
 141                 return -ENOMEM;
 142         }
 143
 144         return 0;
 145 }
 146
 147 void pci_mmcfg_arch_unmap(struct pci_mmcfg_region *cfg)
 148 {
 149         if (cfg && cfg->virt) {
 150                 iounmap(cfg->virt + PCI_MMCFG_BUS_OFFSET(cfg->start_bus));
 151                 cfg->virt = NULL;
 152         }
 153 }