LXR linux/drivers/acpi/reboot.c

   1// SPDX-License-Identifier: GPL-2.0
   2
   3#include <linux/pci.h>
   4#include <linux/acpi.h>
   5#include <acpi/reboot.h>
   6
   7void acpi_reboot(void)
   8{
   9        struct acpi_generic_address *rr;
  10        struct pci_bus *bus0;
  11        u8 reset_value;
  12        unsigned int devfn;
  13
  14        if (acpi_disabled)
  15                return;
  16
  17        rr = &acpi_gbl_FADT.reset_register;
  18
  19        /* ACPI reset register was only introduced with v2 of the FADT */
  20
  21        if (acpi_gbl_FADT.header.revision < 2)
  22                return;
  23
  24        /* Is the reset register supported? The spec says we should be
  25         * checking the bit width and bit offset, but Windows ignores
  26         * these fields */
  27        if (!(acpi_gbl_FADT.flags & ACPI_FADT_RESET_REGISTER))
  28                return;
  29
  30        reset_value = acpi_gbl_FADT.reset_value;
  31
  32        /* The reset register can only exist in I/O, Memory or PCI config space
  33         * on a device on bus 0. */
  34        switch (rr->space_id) {
  35        case ACPI_ADR_SPACE_PCI_CONFIG:
  36                /* The reset register can only live on bus 0. */
  37                bus0 = pci_find_bus(0, 0);
  38                if (!bus0)
  39                        return;
  40                /* Form PCI device/function pair. */
  41                devfn = PCI_DEVFN((rr->address >> 32) & 0xffff,
  42                                  (rr->address >> 16) & 0xffff);
  43                printk(KERN_DEBUG "Resetting with ACPI PCI RESET_REG.");
  44                /* Write the value that resets us. */
  45                pci_bus_write_config_byte(bus0, devfn,
  46                                (rr->address & 0xffff), reset_value);
  47                break;
  48
  49        case ACPI_ADR_SPACE_SYSTEM_MEMORY:
  50        case ACPI_ADR_SPACE_SYSTEM_IO:
  51                printk(KERN_DEBUG "ACPI MEMORY or I/O RESET_REG.\n");
  52                acpi_reset();
  53                break;
  54        }
  55}
  56