1 files changed, 28 insertions, 0 deletions

diff --git a/arch/powerpc/kernel/epapr_hcalls.S b/arch/powerpc/kernel/epapr_hcalls.S
index 697b390ebfd8..62c0dc237826 100644
--- a/arch/powerpc/kernel/epapr_hcalls.S
+++ b/arch/powerpc/kernel/epapr_hcalls.S
@@ -8,13 +8,41 @@
  */
 
 #include <linux/threads.h>
+#include <asm/epapr_hcalls.h>
 #include <asm/reg.h>
 #include <asm/page.h>
 #include <asm/cputable.h>
 #include <asm/thread_info.h>
 #include <asm/ppc_asm.h>
+#include <asm/asm-compat.h>
 #include <asm/asm-offsets.h>
 
+/* epapr_ev_idle() was derived from e500_idle() */
+_GLOBAL(epapr_ev_idle)
+        CURRENT_THREAD_INFO(r3, r1)
+        PPC_LL  r4, TI_LOCAL_FLAGS(r3)  /* set napping bit */
+        ori     r4, r4,_TLF_NAPPING     /* so when we take an exception */
+        PPC_STL r4, TI_LOCAL_FLAGS(r3)  /* it will return to our caller */
+
+        wrteei  1
+
+idle_loop:
+        LOAD_REG_IMMEDIATE(r11, EV_HCALL_TOKEN(EV_IDLE))
+
+.global epapr_ev_idle_start
+epapr_ev_idle_start:
+        li      r3, -1
+        nop
+        nop
+        nop
+
+        /*
+         * Guard against spurious wakeups from a hypervisor --
+         * only interrupt will cause us to return to LR due to
+         * _TLF_NAPPING.
+         */
+        b       idle_loop
+
 /* Hypercall entry point. Will be patched with device tree instructions. */
 .global epapr_hypercall_start
 epapr_hypercall_start: