linux/drivers/acpi/reboot.c
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   1
   2#include <linux/pci.h>
   3#include <linux/acpi.h>
   4#include <acpi/reboot.h>
   5
   6void 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        if (!(acpi_gbl_FADT.flags & ACPI_FADT_RESET_REGISTER))
  27                return;
  28
  29        reset_value = acpi_gbl_FADT.reset_value;
  30
  31        /* The reset register can only exist in I/O, Memory or PCI config space
  32         * on a device on bus 0. */
  33        switch (rr->space_id) {
  34        case ACPI_ADR_SPACE_PCI_CONFIG:
  35                /* The reset register can only live on bus 0. */
  36                bus0 = pci_find_bus(0, 0);
  37                if (!bus0)
  38                        return;
  39                /* Form PCI device/function pair. */
  40                devfn = PCI_DEVFN((rr->address >> 32) & 0xffff,
  41                                  (rr->address >> 16) & 0xffff);
  42                printk(KERN_DEBUG "Resetting with ACPI PCI RESET_REG.");
  43                /* Write the value that resets us. */
  44                pci_bus_write_config_byte(bus0, devfn,
  45                                (rr->address & 0xffff), reset_value);
  46                break;
  47
  48        case ACPI_ADR_SPACE_SYSTEM_MEMORY:
  49        case ACPI_ADR_SPACE_SYSTEM_IO:
  50                printk(KERN_DEBUG "ACPI MEMORY or I/O RESET_REG.\n");
  51                acpi_reset();
  52                break;
  53        }
  54}
  55
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