diff options
Diffstat (limited to 'drivers/acpi/reboot.c')
| -rw-r--r-- | drivers/acpi/reboot.c | 56 |
1 files changed, 42 insertions, 14 deletions
diff --git a/drivers/acpi/reboot.c b/drivers/acpi/reboot.c index a6c77e8b37bd..b79b7c99c237 100644 --- a/drivers/acpi/reboot.c +++ b/drivers/acpi/reboot.c @@ -1,14 +1,42 @@ +// 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; - struct pci_bus *bus0; u8 reset_value; - unsigned int devfn; if (acpi_disabled) return; @@ -32,23 +60,23 @@ void acpi_reboot(void) * 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); + acpi_pci_reboot(rr, 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"); + 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); } |