drivers/acpi/reboot.c

   1
   2 #include <linux/pci.h>
   3 #include <linux/acpi.h>
   4 #include <acpi/reboot.h>
   5
   6 void acpi_reboot(void)
   7 {
   8         struct acpi_generic_address *rr;
   9         struct pci_bus *bus0;
  10         u8 reset_value;
  11         unsigned int devfn;
  12
  13         if (acpi_disabled)
  14                 return;
  15
  16         rr = &acpi_gbl_FADT.reset_register;
  17
  18         /* ACPI reset register was only introduced with v2 of the FADT */
  19
  20         if (acpi_gbl_FADT.header.revision < 2)
  21                 return;
  22
  23         /* Is the reset register supported? The spec says we should be
  24          * checking the bit width and bit offset, but Windows ignores
  25          * these fields */
  26         /* Ignore also acpi_gbl_FADT.flags.ACPI_FADT_RESET_REGISTER */
  27
  28         reset_value = acpi_gbl_FADT.reset_value;
  29
  30         /* The reset register can only exist in I/O, Memory or PCI config space
  31          * on a device on bus 0. */
  32         switch (rr->space_id) {
  33         case ACPI_ADR_SPACE_PCI_CONFIG:
  34                 /* The reset register can only live on bus 0. */
  35                 bus0 = pci_find_bus(0, 0);
  36                 if (!bus0)
  37                         return;
  38                 /* Form PCI device/function pair. */
  39                 devfn = PCI_DEVFN((rr->address >> 32) & 0xffff,
  40                                   (rr->address >> 16) & 0xffff);
  41                 printk(KERN_DEBUG "Resetting with ACPI PCI RESET_REG.");
  42                 /* Write the value that resets us. */
  43                 pci_bus_write_config_byte(bus0, devfn,
  44                                 (rr->address & 0xffff), reset_value);
  45                 break;
  46
  47         case ACPI_ADR_SPACE_SYSTEM_MEMORY:
  48         case ACPI_ADR_SPACE_SYSTEM_IO:
  49                 printk(KERN_DEBUG "ACPI MEMORY or I/O RESET_REG.\n");
  50                 acpi_reset();
  51                 break;
  52         }
  53 }