1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
|
#include <linux/pci.h>
#include <linux/acpi.h>
#include <acpi/reboot.h>
void acpi_reboot(void)
{
struct acpi_generic_address *rr;
struct pci_bus *bus0;
u8 reset_value;
unsigned int devfn;
if (acpi_disabled)
return;
rr = &acpi_gbl_FADT.reset_register;
/*
* Is the ACPI reset register supported?
*
* According to ACPI 3.0, FADT.flags.RESET_REG_SUP indicates
* whether the ACPI reset mechanism is supported.
*
* However, some boxes have this bit clear, yet a valid
* ACPI_RESET_REG & RESET_VALUE, and ACPI reboot is the only
* mechanism that works for them after S3.
*
* This suggests that other operating systems may not be checking
* the RESET_REG_SUP bit, and are using other means to decide
* whether to use the ACPI reboot mechanism or not.
*
* So when acpi reboot is requested,
* only the reset_register is checked. If the following
* conditions are met, it indicates that the reset register is supported.
* a. reset_register is not zero
* b. the access width is eight
* c. the bit_offset is zero
*/
if (!(rr->address) || rr->bit_width != 8 || rr->bit_offset != 0)
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:
/* 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);
printk(KERN_DEBUG "Resetting with ACPI PCI RESET_REG.");
/* Write the value that resets us. */
pci_bus_write_config_byte(bus0, devfn,
(rr->address & 0xffff), 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_hw_low_level_write(8, reset_value, rr);
break;
}
/* Wait ten seconds */
acpi_os_stall(10000000);
}
|
