Root/drivers/acpi/reboot.c

1
2#include <linux/pci.h>
3#include <linux/acpi.h>
4#include <acpi/reboot.h>
5
6void 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
18    /* ACPI reset register was only introduced with v2 of the FADT */
19
20    if (acpi_gbl_FADT.header.revision < 2)
21        return;
22
23    /* Is the reset register supported? The spec says we should be
24     * checking the bit width and bit offset, but Windows ignores
25     * these fields */
26    if (!(acpi_gbl_FADT.flags & ACPI_FADT_RESET_REGISTER))
27        return;
28
29    reset_value = acpi_gbl_FADT.reset_value;
30
31    /* The reset register can only exist in I/O, Memory or PCI config space
32     * on a device on bus 0. */
33    switch (rr->space_id) {
34    case ACPI_ADR_SPACE_PCI_CONFIG:
35        /* The reset register can only live on bus 0. */
36        bus0 = pci_find_bus(0, 0);
37        if (!bus0)
38            return;
39        /* Form PCI device/function pair. */
40        devfn = PCI_DEVFN((rr->address >> 32) & 0xffff,
41                  (rr->address >> 16) & 0xffff);
42        printk(KERN_DEBUG "Resetting with ACPI PCI RESET_REG.");
43        /* Write the value that resets us. */
44        pci_bus_write_config_byte(bus0, devfn,
45                (rr->address & 0xffff), reset_value);
46        break;
47
48    case ACPI_ADR_SPACE_SYSTEM_MEMORY:
49    case ACPI_ADR_SPACE_SYSTEM_IO:
50        printk(KERN_DEBUG "ACPI MEMORY or I/O RESET_REG.\n");
51        acpi_reset();
52        break;
53    }
54}
55

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