powerpc: Add paravirt idle loop for 64-bit Book-E

Signed-off-by: Stuart Yoder <[e-mail]>
Signed-off-by: Kumar Gala <[e-mail]>

arch/powerpc/kernel/epapr_hcalls.S

···
 #include <asm/asm-compat.h>
 #include <asm/asm-offsets.h>
 
+#ifndef CONFIG_PPC64
 /* epapr_ev_idle() was derived from e500_idle() */
 _GLOBAL(epapr_ev_idle)
 	CURRENT_THREAD_INFO(r3, r1)
···
 	 * _TLF_NAPPING.
 	 */
 	b	idle_loop
+#endif
 
 /* Hypercall entry point. Will be patched with device tree instructions. */
 .global epapr_hypercall_start

arch/powerpc/kernel/idle_book3e.S

···
 #include <asm/ppc-opcode.h>
 #include <asm/processor.h>
 #include <asm/thread_info.h>
+#include <asm/epapr_hcalls.h>
 
 /* 64-bit version only for now */
 #ifdef CONFIG_PPC64
 
-_GLOBAL(book3e_idle)
+.macro BOOK3E_IDLE name loop
+_GLOBAL(\name)
 	/* Save LR for later */
 	mflr	r0
 	std	r0,16(r1)
···
 
 	/* We can now re-enable hard interrupts and go to sleep */
 	wrteei	1
-1:	PPC_WAIT(0)
+	\loop
+
+.endm
+
+.macro BOOK3E_IDLE_LOOP
+1:
+	PPC_WAIT(0)
 	b	1b
+.endm
+
+/* epapr_ev_idle_start below is patched with the proper hcall
+   opcodes during kernel initialization */
+.macro EPAPR_EV_IDLE_LOOP
+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
+	b       idle_loop
+.endm
+
+BOOK3E_IDLE epapr_ev_idle EPAPR_EV_IDLE_LOOP
+
+BOOK3E_IDLE book3e_idle BOOK3E_IDLE_LOOP
 
 #endif /* CONFIG_PPC64 */