xen/acpi/sleep: Enable ACPI sleep via the __acpi_os_prepare_sleep

Provide the registration callback to call in the Xen's
ACPI sleep functionality. This means that during S3/S5
we make a hypercall XENPF_enter_acpi_sleep with the
proper PM1A/PM1B registers.

Based of Ke Yu's <ke.yu@intel.com> initial idea.
[ From http://xenbits.xensource.com/linux-2.6.18-xen.hg
change c68699484a65 ]

[v1: Added Copyright and license]
[v2: Added check if PM1A/B the 16-bits MSB contain something. The spec
     only uses 16-bits but might have more in future]
Signed-off-by: Liang Tang <liang.tang@oracle.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

1 files changed, 3 insertions, 0 deletions

diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
index 1ed61c2bf633..eca90e5be1e7 100644
--- a/arch/x86/xen/enlighten.c
+++ b/arch/x86/xen/enlighten.c
@@ -42,6 +42,7 @@
 #include <xen/page.h>
 #include <xen/hvm.h>
 #include <xen/hvc-console.h>
+#include <xen/acpi.h>
 
 #include <asm/paravirt.h>
 #include <asm/apic.h>
@@ -1373,6 +1374,8 @@ asmlinkage void __init xen_start_kernel(void)
 
                 /* Make sure ACS will be enabled */
                 pci_request_acs();
+
+                xen_acpi_sleep_register();
         }