// SPDX-License-Identifier: GPL-2.0 #include <linux/pci.h> #include <linux/acpi.h> #include <acpi/reboot.h> #ifdef CONFIG_PCI static void acpi_pci_reboot(struct acpi_generic_address *rr, u8 reset_value) { unsigned int devfn; struct pci_bus *bus0; /* The reset register can only live on bus 0. */ bus0 = pci_find_bus(0, 0); if (!bus0) return; /* Form PCI device/function pair. */ devfn = PCI_DEVFN((rr->address >> 32) & 0xffff, (rr->address >> 16) & 0xffff); pr_debug("Resetting with ACPI PCI RESET_REG.\n"); /* Write the value that resets us. */ pci_bus_write_config_byte(bus0, devfn, (rr->address & 0xffff), reset_value); } #else static inline void acpi_pci_reboot(struct acpi_generic_address *rr, u8 reset_value) { pr_warn_once("PCI configuration space access is not supported\n"); } #endif void acpi_reboot(void) { struct acpi_generic_address *rr; u8 reset_value; if (acpi_disabled) return; rr = &acpi_gbl_FADT.reset_register; /* ACPI reset register was only introduced with v2 of the FADT */ if (acpi_gbl_FADT.header.revision < 2) return; /* Is the reset register supported? The spec says we should be * checking the bit width and bit offset, but Windows ignores * these fields */ if (!(acpi_gbl_FADT.flags & ACPI_FADT_RESET_REGISTER)) return; reset_value = acpi_gbl_FADT.reset_value; /* The reset register can only exist in I/O, Memory or PCI config space * on a device on bus 0. */ switch (rr->space_id) { case ACPI_ADR_SPACE_PCI_CONFIG: acpi_pci_reboot(rr, reset_value); break; case ACPI_ADR_SPACE_SYSTEM_MEMORY: case ACPI_ADR_SPACE_SYSTEM_IO: printk(KERN_DEBUG "ACPI MEMORY or I/O RESET_REG.\n"); acpi_reset(); break; } }