Commit | Line | Data |
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4d387043 AD |
1 | |
2 | #include <linux/pci.h> | |
3 | #include <linux/acpi.h> | |
4 | #include <acpi/reboot.h> | |
5 | ||
6 | void 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 | ||
8fd14591 ZY |
18 | /* |
19 | * Is the ACPI reset register supported? | |
20 | * | |
21 | * According to ACPI 3.0, FADT.flags.RESET_REG_SUP indicates | |
22 | * whether the ACPI reset mechanism is supported. | |
23 | * | |
24 | * However, some boxes have this bit clear, yet a valid | |
25 | * ACPI_RESET_REG & RESET_VALUE, and ACPI reboot is the only | |
26 | * mechanism that works for them after S3. | |
27 | * | |
28 | * This suggests that other operating systems may not be checking | |
29 | * the RESET_REG_SUP bit, and are using other means to decide | |
30 | * whether to use the ACPI reboot mechanism or not. | |
31 | * | |
32 | * So when acpi reboot is requested, | |
33 | * only the reset_register is checked. If the following | |
34 | * conditions are met, it indicates that the reset register is supported. | |
35 | * a. reset_register is not zero | |
36 | * b. the access width is eight | |
37 | * c. the bit_offset is zero | |
38 | */ | |
39 | if (!(rr->address) || rr->bit_width != 8 || rr->bit_offset != 0) | |
4d387043 AD |
40 | return; |
41 | ||
42 | reset_value = acpi_gbl_FADT.reset_value; | |
43 | ||
44 | /* The reset register can only exist in I/O, Memory or PCI config space | |
45 | * on a device on bus 0. */ | |
46 | switch (rr->space_id) { | |
47 | case ACPI_ADR_SPACE_PCI_CONFIG: | |
48 | /* The reset register can only live on bus 0. */ | |
49 | bus0 = pci_find_bus(0, 0); | |
50 | if (!bus0) | |
51 | return; | |
52 | /* Form PCI device/function pair. */ | |
53 | devfn = PCI_DEVFN((rr->address >> 32) & 0xffff, | |
54 | (rr->address >> 16) & 0xffff); | |
55 | printk(KERN_DEBUG "Resetting with ACPI PCI RESET_REG."); | |
56 | /* Write the value that resets us. */ | |
57 | pci_bus_write_config_byte(bus0, devfn, | |
58 | (rr->address & 0xffff), reset_value); | |
59 | break; | |
60 | ||
61 | case ACPI_ADR_SPACE_SYSTEM_MEMORY: | |
62 | case ACPI_ADR_SPACE_SYSTEM_IO: | |
63 | printk(KERN_DEBUG "ACPI MEMORY or I/O RESET_REG.\n"); | |
64 | acpi_hw_low_level_write(8, reset_value, rr); | |
65 | break; | |
66 | } | |
67 | /* Wait ten seconds */ | |
68 | acpi_os_stall(10000000); | |
69 | } |