83 lines
2.0 KiB
C
83 lines
2.0 KiB
C
// SPDX-License-Identifier: GPL-2.0
|
|
|
|
#define pr_fmt(fmt) "ACPI: " fmt
|
|
|
|
#include <linux/pci.h>
|
|
#include <linux/acpi.h>
|
|
#include <acpi/reboot.h>
|
|
#include <linux/delay.h>
|
|
|
|
#ifdef CONFIG_PCI
|
|
static void acpi_pci_reboot(struct acpi_generic_address *rr, u8 reset_value)
|
|
{
|
|
unsigned int devfn;
|
|
struct pci_bus *bus0;
|
|
|
|
/* 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);
|
|
pr_debug("Resetting with ACPI PCI RESET_REG.\n");
|
|
/* Write the value that resets us. */
|
|
pci_bus_write_config_byte(bus0, devfn,
|
|
(rr->address & 0xffff), reset_value);
|
|
}
|
|
#else
|
|
static inline void acpi_pci_reboot(struct acpi_generic_address *rr,
|
|
u8 reset_value)
|
|
{
|
|
pr_warn_once("PCI configuration space access is not supported\n");
|
|
}
|
|
#endif
|
|
|
|
void acpi_reboot(void)
|
|
{
|
|
struct acpi_generic_address *rr;
|
|
u8 reset_value;
|
|
|
|
if (acpi_disabled)
|
|
return;
|
|
|
|
rr = &acpi_gbl_FADT.reset_register;
|
|
|
|
/* ACPI reset register was only introduced with v2 of the FADT */
|
|
|
|
if (acpi_gbl_FADT.header.revision < 2)
|
|
return;
|
|
|
|
/* Is the reset register supported? The spec says we should be
|
|
* checking the bit width and bit offset, but Windows ignores
|
|
* these fields */
|
|
if (!(acpi_gbl_FADT.flags & ACPI_FADT_RESET_REGISTER))
|
|
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:
|
|
acpi_pci_reboot(rr, reset_value);
|
|
break;
|
|
|
|
case ACPI_ADR_SPACE_SYSTEM_MEMORY:
|
|
case ACPI_ADR_SPACE_SYSTEM_IO:
|
|
pr_debug("ACPI MEMORY or I/O RESET_REG.\n");
|
|
acpi_reset();
|
|
break;
|
|
}
|
|
|
|
/*
|
|
* Some platforms do not shut down immediately after writing to the
|
|
* ACPI reset register, and this results in racing with the
|
|
* subsequent reboot mechanism.
|
|
*
|
|
* The 15ms delay has been found to be long enough for the system
|
|
* to reboot on the affected platforms.
|
|
*/
|
|
mdelay(15);
|
|
}
|