| Aaron Durbin | 4d38704 | 2008-07-16 23:27:08 +0200 | [diff] [blame] | 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 | |
| Zhao Yakui | 8fd1459 | 2008-10-17 14:22:27 -0400 | [diff] [blame] | 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) |
| Aaron Durbin | 4d38704 | 2008-07-16 23:27:08 +0200 | [diff] [blame] | 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 | } |