powerpc/powernv: Add OPAL call to resync timebase on wakeup

During "Fast-sleep" and deeper power savings state, decrementer and
timebase could be stopped making it out of sync with rest
of the cores in the system.

Add a firmware call to request platform to resync timebase
using low level platform methods.

Signed-off-by: Vaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com>
Signed-off-by: Preeti U. Murthy <preeti@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

4 files changed, 31 insertions, 1 deletions

diff --git a/arch/powerpc/include/asm/opal.h b/arch/powerpc/include/asm/opal.h
index 40157e2ca691..c71c72e47d47 100644
--- a/arch/powerpc/include/asm/opal.h
+++ b/arch/powerpc/include/asm/opal.h
@@ -154,6 +154,7 @@ extern int opal_enter_rtas(struct rtas_args *args,
 #define OPAL_FLASH_VALIDATE                     76
 #define OPAL_FLASH_MANAGE                       77
 #define OPAL_FLASH_UPDATE                       78
+#define OPAL_RESYNC_TIMEBASE                    79
 #define OPAL_GET_MSG                            85
 #define OPAL_CHECK_ASYNC_COMPLETION             86
 #define OPAL_SYNC_HOST_REBOOT                   87
@@ -865,6 +866,7 @@ extern void opal_flash_init(void);
 extern int opal_machine_check(struct pt_regs *regs);
 
 extern void opal_shutdown(void);
+extern int opal_resync_timebase(void);
 
 extern void opal_lpc_init(void);
 
diff --git a/arch/powerpc/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S
index b01a9cb441e4..9533d7a9223c 100644
--- a/arch/powerpc/kernel/exceptions-64s.S
+++ b/arch/powerpc/kernel/exceptions-64s.S
@@ -145,7 +145,7 @@ BEGIN_FTR_SECTION
 
         /* Fast Sleep wakeup on PowerNV */
 8:      GET_PACA(r13)
-        b       .power7_wakeup_loss
+        b       .power7_wakeup_tb_loss
 
 9:
 END_FTR_SECTION_IFSET(CPU_FTR_HVMODE | CPU_FTR_ARCH_206)
diff --git a/arch/powerpc/kernel/idle_power7.S b/arch/powerpc/kernel/idle_power7.S
index 14f78bec62c4..c3ab86975614 100644
--- a/arch/powerpc/kernel/idle_power7.S
+++ b/arch/powerpc/kernel/idle_power7.S
@@ -17,6 +17,7 @@
 #include <asm/ppc-opcode.h>
 #include <asm/hw_irq.h>
 #include <asm/kvm_book3s_asm.h>
+#include <asm/opal.h>
 
 #undef DEBUG
 
@@ -125,6 +126,32 @@ _GLOBAL(power7_sleep)
         b       power7_powersave_common
         /* No return */
 
+_GLOBAL(power7_wakeup_tb_loss)
+        ld      r2,PACATOC(r13);
+        ld      r1,PACAR1(r13)
+
+        /* Time base re-sync */
+        li      r0,OPAL_RESYNC_TIMEBASE
+        LOAD_REG_ADDR(r11,opal);
+        ld      r12,8(r11);
+        ld      r2,0(r11);
+        mtctr   r12
+        bctrl
+
+        /* TODO: Check r3 for failure */
+
+        REST_NVGPRS(r1)
+        REST_GPR(2, r1)
+        ld      r3,_CCR(r1)
+        ld      r4,_MSR(r1)
+        ld      r5,_NIP(r1)
+        addi    r1,r1,INT_FRAME_SIZE
+        mtcr    r3
+        mfspr   r3,SPRN_SRR1            /* Return SRR1 */
+        mtspr   SPRN_SRR1,r4
+        mtspr   SPRN_SRR0,r5
+        rfid
+
 _GLOBAL(power7_wakeup_loss)
         ld      r1,PACAR1(r13)
         REST_NVGPRS(r1)
diff --git a/arch/powerpc/platforms/powernv/opal-wrappers.S b/arch/powerpc/platforms/powernv/opal-wrappers.S
index 3e8829c40fbb..aab54b60334f 100644
--- a/arch/powerpc/platforms/powernv/opal-wrappers.S
+++ b/arch/powerpc/platforms/powernv/opal-wrappers.S
@@ -126,6 +126,7 @@ OPAL_CALL(opal_return_cpu,			OPAL_RETURN_CPU);
 OPAL_CALL(opal_validate_flash,                  OPAL_FLASH_VALIDATE);
 OPAL_CALL(opal_manage_flash,                    OPAL_FLASH_MANAGE);
 OPAL_CALL(opal_update_flash,                    OPAL_FLASH_UPDATE);
+OPAL_CALL(opal_resync_timebase,                 OPAL_RESYNC_TIMEBASE);
 OPAL_CALL(opal_get_msg,                         OPAL_GET_MSG);
 OPAL_CALL(opal_check_completion,                OPAL_CHECK_ASYNC_COMPLETION);
 OPAL_CALL(opal_sync_host_reboot,                OPAL_SYNC_HOST_REBOOT);