x86/reboot: Add EFI reboot quirk for ACPI Hardware Reduced flag

It appears that the BayTrail-T class of hardware requires EFI in order
to powerdown and reboot and no other reliable method exists.

This quirk is generally applicable to all hardware that has the ACPI
Hardware Reduced bit set, since usually ACPI would be the preferred
method.

Cc: Len Brown <len.brown@intel.com>
Cc: Mark Salter <msalter@redhat.com>
Cc: "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>
Signed-off-by: Matt Fleming <matt.fleming@intel.com>

diff --git a/arch/x86/include/asm/efi.h b/arch/x86/include/asm/efi.h
index 9043f365ebf55ff85b612d22524294903cd3d2ef..044a2fd3c5fe78647d4caf9ef6f92136c499ee38 100644 (file)
--- a/arch/x86/include/asm/efi.h
+++ b/arch/x86/include/asm/efi.h
@@ -183,6 +183,8 @@ extern struct efi_config *efi_early;
 #define efi_call_early(f, ...)                                         \
        efi_early->call(efi_early->f, __VA_ARGS__);
 
+extern bool efi_reboot_required(void);
+
 #else
 /*
  * IF EFI is not configured, have the EFI calls return -ENOSYS.
@@ -195,6 +197,10 @@ extern struct efi_config *efi_early;
 #define efi_call5(_f, _a1, _a2, _a3, _a4, _a5)         (-ENOSYS)
 #define efi_call6(_f, _a1, _a2, _a3, _a4, _a5, _a6)    (-ENOSYS)
 static inline void parse_efi_setup(u64 phys_addr, u32 data_len) {}
+static inline bool efi_reboot_required(void)
+{
+       return false;
+}
 #endif /* CONFIG_EFI */
 
 #endif /* _ASM_X86_EFI_H */

diff --git a/arch/x86/kernel/reboot.c b/arch/x86/kernel/reboot.c
index 09e709fd1830a83ae0112fde75951de7db57d45c..17962e667a91c64f7e99e62a04d83b253823691d 100644 (file)
--- a/arch/x86/kernel/reboot.c
+++ b/arch/x86/kernel/reboot.c
@@ -28,6 +28,7 @@
 #include <linux/mc146818rtc.h>
 #include <asm/realmode.h>
 #include <asm/x86_init.h>
+#include <asm/efi.h>
 
 /*
  * Power off function, if any
@@ -401,12 +402,25 @@ static struct dmi_system_id __initdata reboot_dmi_table[] = {
 
 static int __init reboot_init(void)
 {
+       int rv;
+
        /*
         * Only do the DMI check if reboot_type hasn't been overridden
         * on the command line
         */
-       if (reboot_default)
-               dmi_check_system(reboot_dmi_table);
+       if (!reboot_default)
+               return 0;
+
+       /*
+        * The DMI quirks table takes precedence. If no quirks entry
+        * matches and the ACPI Hardware Reduced bit is set, force EFI
+        * reboot.
+        */
+       rv = dmi_check_system(reboot_dmi_table);
+
+       if (!rv && efi_reboot_required())
+               reboot_type = BOOT_EFI;
+
        return 0;
 }
 core_initcall(reboot_init);

diff --git a/arch/x86/platform/efi/quirks.c b/arch/x86/platform/efi/quirks.c
index b4cb9182f1551d00175cc033a98d667534ef6798..1c7380da65ffab641f0cb0aedc88cb7ef7e8f6cc 100644 (file)
--- a/arch/x86/platform/efi/quirks.c
+++ b/arch/x86/platform/efi/quirks.c
@@ -7,6 +7,7 @@
 #include <linux/slab.h>
 #include <linux/memblock.h>
 #include <linux/bootmem.h>
+#include <linux/acpi.h>
 #include <asm/efi.h>
 #include <asm/uv/uv.h>
 
@@ -265,3 +266,25 @@ void __init efi_apply_memmap_quirks(void)
        if (is_uv_system())
                set_bit(EFI_OLD_MEMMAP, &efi.flags);
 }
+
+/*
+ * For most modern platforms the preferred method of powering off is via
+ * ACPI. However, there are some that are known to require the use of
+ * EFI runtime services and for which ACPI does not work at all.
+ *
+ * Using EFI is a last resort, to be used only if no other option
+ * exists.
+ */
+bool efi_reboot_required(void)
+{
+       if (!acpi_gbl_reduced_hardware)
+               return false;
+
+       efi_reboot_quirk_mode = EFI_RESET_WARM;
+       return true;
+}
+
+bool efi_poweroff_required(void)
+{
+       return !!acpi_gbl_reduced_hardware;
+}

diff --git a/drivers/firmware/efi/reboot.c b/drivers/firmware/efi/reboot.c
index e9eeeb3c6345b64b294c54948f60024beb4de78b..9c59d1c795d1f2d6787b9a3a248f384e4017e8f1 100644 (file)
--- a/drivers/firmware/efi/reboot.c
+++ b/drivers/firmware/efi/reboot.c
@@ -5,6 +5,8 @@
 #include <linux/efi.h>
 #include <linux/reboot.h>
 
+int efi_reboot_quirk_mode = -1;
+
 void efi_reboot(enum reboot_mode reboot_mode, const char *__unused)
 {
        int efi_mode;
@@ -22,6 +24,12 @@ void efi_reboot(enum reboot_mode reboot_mode, const char *__unused)
                break;
        }
 
+       /*
+        * If a quirk forced an EFI reset mode, always use that.
+        */
+       if (efi_reboot_quirk_mode != -1)
+               efi_mode = efi_reboot_quirk_mode;
+
        efi.reset_system(efi_mode, EFI_SUCCESS, 0, NULL);
 }
 

diff --git a/include/linux/efi.h b/include/linux/efi.h
index 9917f58ee83eed95cc5f8aab73201d0f509cf516..bac0f93dc4734c3ca63ae8c8f709113f6fbbbc04 100644 (file)
--- a/include/linux/efi.h
+++ b/include/linux/efi.h
@@ -878,6 +878,7 @@ extern void efi_reserve_boot_services(void);
 extern int efi_get_fdt_params(struct efi_fdt_params *params, int verbose);
 extern struct efi_memory_map memmap;
 
+extern int efi_reboot_quirk_mode;
 extern bool efi_poweroff_required(void);
 
 /* Iterate through an efi_memory_map */