[PATCH 3/7] x86/acpi/sleep: Provide registration for acpi_suspend_lowlevel.

[Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>]

Which by default will be x86_acpi_suspend_lowlevel.
This registration allows us to register another callback
if there is a need to use another platform specific callback.

CC: Thomas Gleixner <tglx@linutronix.de>
CC: "H. Peter Anvin" <hpa@zytor.com>
CC: x86@kernel.org
CC: Len Brown <len.brown@intel.com>
CC: Joseph Cihula <joseph.cihula@intel.com>
CC: Shane Wang <shane.wang@intel.com>
CC: linux-pm@lists.linux-foundation.org
CC: linux-acpi@vger.kernel.org
CC: Len Brown <len.brown@intel.com>
Signed-off-by: Liang Tang <liang.tang@oracle.com>
[v1: Fix when CONFIG_ACPI_SLEEP is not set]
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
---
 arch/x86/include/asm/acpi.h  |    2 +-
 arch/x86/kernel/acpi/boot.c  |    7 +++++++
 arch/x86/kernel/acpi/sleep.c |    4 ++--
 arch/x86/kernel/acpi/sleep.h |    2 ++
 drivers/acpi/sleep.c         |    2 ++
 5 files changed, 14 insertions(+), 3 deletions(-)

diff --git a/arch/x86/include/asm/acpi.h b/arch/x86/include/asm/acpi.h
index 610001d..68cf060 100644
--- a/arch/x86/include/asm/acpi.h
+++ b/arch/x86/include/asm/acpi.h
@@ -115,7 +115,7 @@ static inline void acpi_disable_pci(void)
 }
 
 /* Low-level suspend routine. */
-extern int acpi_suspend_lowlevel(void);
+extern int (*acpi_suspend_lowlevel)(void);
 
 extern const unsigned char acpi_wakeup_code[];
 #define acpi_wakeup_address (__pa(TRAMPOLINE_SYM(acpi_wakeup_code)))
diff --git a/arch/x86/kernel/acpi/boot.c b/arch/x86/kernel/acpi/boot.c
index 4558f0d..90e06ef 100644
--- a/arch/x86/kernel/acpi/boot.c
+++ b/arch/x86/kernel/acpi/boot.c
@@ -44,6 +44,7 @@
 #include <asm/mpspec.h>
 #include <asm/smp.h>
 
+#include "sleep.h" /* To include x86_acpi_suspend_lowlevel */
 static int __initdata acpi_force = 0;
 u32 acpi_rsdt_forced;
 int acpi_disabled;
@@ -552,6 +553,12 @@ static int acpi_register_gsi_ioapic(struct device *dev, u32 gsi,
 int (*__acpi_register_gsi)(struct device *dev, u32 gsi,
 			   int trigger, int polarity) = acpi_register_gsi_pic;
 
+#ifdef CONFIG_ACPI_SLEEP
+int (*acpi_suspend_lowlevel)(void) = x86_acpi_suspend_lowlevel;
+#else
+int (*acpi_suspend_lowlevel)(void);
+#endif
+
 /*
  * success: return IRQ number (>=0)
  * failure: return < 0
diff --git a/arch/x86/kernel/acpi/sleep.c b/arch/x86/kernel/acpi/sleep.c
index 103b6ab..4d2d0b1 100644
--- a/arch/x86/kernel/acpi/sleep.c
+++ b/arch/x86/kernel/acpi/sleep.c
@@ -25,12 +25,12 @@ static char temp_stack[4096];
 #endif
 
 /**
- * acpi_suspend_lowlevel - save kernel state
+ * x86_acpi_suspend_lowlevel - save kernel state
  *
  * Create an identity mapped page table and copy the wakeup routine to
  * low memory.
  */
-int acpi_suspend_lowlevel(void)
+int x86_acpi_suspend_lowlevel(void)
 {
 	struct wakeup_header *header;
 	/* address in low memory of the wakeup routine. */
diff --git a/arch/x86/kernel/acpi/sleep.h b/arch/x86/kernel/acpi/sleep.h
index 416d4be..4d3feb5 100644
--- a/arch/x86/kernel/acpi/sleep.h
+++ b/arch/x86/kernel/acpi/sleep.h
@@ -13,3 +13,5 @@ extern unsigned long acpi_copy_wakeup_routine(unsigned long);
 extern void wakeup_long64(void);
 
 extern void do_suspend_lowlevel(void);
+
+extern int x86_acpi_suspend_lowlevel(void);
diff --git a/drivers/acpi/sleep.c b/drivers/acpi/sleep.c
index 6d9a3ab..355fa4b 100644
--- a/drivers/acpi/sleep.c
+++ b/drivers/acpi/sleep.c
@@ -254,6 +254,8 @@ static int acpi_suspend_enter(suspend_state_t pm_state)
 		break;
 
 	case ACPI_STATE_S3:
+		if (!acpi_suspend_lowlevel)
+			return -ENOSYS;
 		error = acpi_suspend_lowlevel();
 		if (error)
 			return error;
-- 
1.7.7.4