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}

 1// SPDX-License-Identifier: GPL-2.0
 2
 3#define pr_fmt(fmt) "ACPI: " fmt
 4
 5#include <linux/pci.h>
 6#include <linux/acpi.h>
 7#include <acpi/reboot.h>
 8#include <linux/delay.h>
 9
10#ifdef CONFIG_PCI
11static void acpi_pci_reboot(struct acpi_generic_address *rr, u8 reset_value)
12{
13	unsigned int devfn;
14	struct pci_bus *bus0;
15
16	/* The reset register can only live on bus 0. */
17	bus0 = pci_find_bus(0, 0);
18	if (!bus0)
19		return;
20	/* Form PCI device/function pair. */
21	devfn = PCI_DEVFN((rr->address >> 32) & 0xffff,
22			  (rr->address >> 16) & 0xffff);
23	pr_debug("Resetting with ACPI PCI RESET_REG.\n");
24	/* Write the value that resets us. */
25	pci_bus_write_config_byte(bus0, devfn,
26			(rr->address & 0xffff), reset_value);
27}
28#else
29static inline void acpi_pci_reboot(struct acpi_generic_address *rr,
30				   u8 reset_value)
31{
32	pr_warn_once("PCI configuration space access is not supported\n");
33}
34#endif
35
36void acpi_reboot(void)
37{
38	struct acpi_generic_address *rr;
 
39	u8 reset_value;
 
40
41	if (acpi_disabled)
42		return;
43
44	rr = &acpi_gbl_FADT.reset_register;
45
46	/* ACPI reset register was only introduced with v2 of the FADT */
47
48	if (acpi_gbl_FADT.header.revision < 2)
49		return;
50
51	/* Is the reset register supported? The spec says we should be
52	 * checking the bit width and bit offset, but Windows ignores
53	 * these fields */
54	if (!(acpi_gbl_FADT.flags & ACPI_FADT_RESET_REGISTER))
55		return;
56
57	reset_value = acpi_gbl_FADT.reset_value;
58
59	/* The reset register can only exist in I/O, Memory or PCI config space
60	 * on a device on bus 0. */
61	switch (rr->space_id) {
62	case ACPI_ADR_SPACE_PCI_CONFIG:
63		acpi_pci_reboot(rr, reset_value);
 
 
 
 
 
 
 
 
 
 
64		break;
65
66	case ACPI_ADR_SPACE_SYSTEM_MEMORY:
67	case ACPI_ADR_SPACE_SYSTEM_IO:
68		pr_debug("ACPI MEMORY or I/O RESET_REG.\n");
69		acpi_reset();
70		break;
71	}
72
73	/*
74	 * Some platforms do not shut down immediately after writing to the
75	 * ACPI reset register, and this results in racing with the
76	 * subsequent reboot mechanism.
77	 *
78	 * The 15ms delay has been found to be long enough for the system
79	 * to reboot on the affected platforms.
80	 */
81	mdelay(15);
82}