1 // SPDX-License-Identifier: GPL-2.0
4 #include <linux/acpi.h>
5 #include <acpi/reboot.h>
8 static void acpi_pci_reboot(struct acpi_generic_address *rr, u8 reset_value)
13 /* The reset register can only live on bus 0. */
14 bus0 = pci_find_bus(0, 0);
17 /* Form PCI device/function pair. */
18 devfn = PCI_DEVFN((rr->address >> 32) & 0xffff,
19 (rr->address >> 16) & 0xffff);
20 pr_debug("Resetting with ACPI PCI RESET_REG.\n");
21 /* Write the value that resets us. */
22 pci_bus_write_config_byte(bus0, devfn,
23 (rr->address & 0xffff), reset_value);
26 static inline void acpi_pci_reboot(struct acpi_generic_address *rr,
29 pr_warn_once("PCI configuration space access is not supported\n");
33 void acpi_reboot(void)
35 struct acpi_generic_address *rr;
41 rr = &acpi_gbl_FADT.reset_register;
43 /* ACPI reset register was only introduced with v2 of the FADT */
45 if (acpi_gbl_FADT.header.revision < 2)
48 /* Is the reset register supported? The spec says we should be
49 * checking the bit width and bit offset, but Windows ignores
51 if (!(acpi_gbl_FADT.flags & ACPI_FADT_RESET_REGISTER))
54 reset_value = acpi_gbl_FADT.reset_value;
56 /* The reset register can only exist in I/O, Memory or PCI config space
57 * on a device on bus 0. */
58 switch (rr->space_id) {
59 case ACPI_ADR_SPACE_PCI_CONFIG:
60 acpi_pci_reboot(rr, reset_value);
63 case ACPI_ADR_SPACE_SYSTEM_MEMORY:
64 case ACPI_ADR_SPACE_SYSTEM_IO:
65 printk(KERN_DEBUG "ACPI MEMORY or I/O RESET_REG.\n");