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b2441318 | 1 | // SPDX-License-Identifier: GPL-2.0 |
4d387043 AD |
2 | |
3 | #include <linux/pci.h> | |
4 | #include <linux/acpi.h> | |
5 | #include <acpi/reboot.h> | |
6 | ||
86689776 | 7 | #ifdef CONFIG_PCI |
36ad7d2b SK |
8 | static void acpi_pci_reboot(struct acpi_generic_address *rr, u8 reset_value) |
9 | { | |
10 | unsigned int devfn; | |
11 | struct pci_bus *bus0; | |
12 | ||
13 | /* The reset register can only live on bus 0. */ | |
14 | bus0 = pci_find_bus(0, 0); | |
15 | if (!bus0) | |
16 | return; | |
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); | |
24 | } | |
86689776 SK |
25 | #else |
26 | static inline void acpi_pci_reboot(struct acpi_generic_address *rr, | |
27 | u8 reset_value) | |
28 | { | |
29 | pr_warn_once("PCI configuration space access is not supported\n"); | |
30 | } | |
31 | #endif | |
36ad7d2b | 32 | |
4d387043 AD |
33 | void acpi_reboot(void) |
34 | { | |
35 | struct acpi_generic_address *rr; | |
dd73e722 | 36 | u8 reset_value; |
4d387043 AD |
37 | |
38 | if (acpi_disabled) | |
39 | return; | |
40 | ||
41 | rr = &acpi_gbl_FADT.reset_register; | |
42 | ||
95cf3e12 MG |
43 | /* ACPI reset register was only introduced with v2 of the FADT */ |
44 | ||
45 | if (acpi_gbl_FADT.header.revision < 2) | |
46 | return; | |
47 | ||
6734fe57 MG |
48 | /* Is the reset register supported? The spec says we should be |
49 | * checking the bit width and bit offset, but Windows ignores | |
50 | * these fields */ | |
19244ad0 LT |
51 | if (!(acpi_gbl_FADT.flags & ACPI_FADT_RESET_REGISTER)) |
52 | return; | |
4d387043 AD |
53 | |
54 | reset_value = acpi_gbl_FADT.reset_value; | |
55 | ||
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: | |
36ad7d2b | 60 | acpi_pci_reboot(rr, reset_value); |
4d387043 AD |
61 | break; |
62 | ||
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"); | |
2ee62612 | 66 | acpi_reset(); |
4d387043 AD |
67 | break; |
68 | } | |
4d387043 | 69 | } |