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

 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}