[PATCH v2 2/3] powerpc/powernv/idle: save-restore DAWR0,DAWRX0 for P10

[Pratik Rajesh Sampat]

Additional registers DAWR0, DAWRX0 may be lost on Power 10 for
stop levels < 4.
Therefore save the values of these SPRs before entering a  "stop"
state and restore their values on wakeup.

Signed-off-by: Pratik Rajesh Sampat <psam...@linux.ibm.com>
---
 arch/powerpc/platforms/powernv/idle.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/arch/powerpc/platforms/powernv/idle.c 
b/arch/powerpc/platforms/powernv/idle.c
index 19d94d021357..f2e2a6a4c274 100644
--- a/arch/powerpc/platforms/powernv/idle.c
+++ b/arch/powerpc/platforms/powernv/idle.c
@@ -600,6 +600,8 @@ struct p9_sprs {
        u64 iamr;
        u64 amor;
        u64 uamor;
+       u64 dawr0;
+       u64 dawrx0;
 };
 
 static unsigned long power9_idle_stop(unsigned long psscr, bool mmu_on)
@@ -687,6 +689,10 @@ static unsigned long power9_idle_stop(unsigned long psscr, 
bool mmu_on)
        sprs.iamr       = mfspr(SPRN_IAMR);
        sprs.amor       = mfspr(SPRN_AMOR);
        sprs.uamor      = mfspr(SPRN_UAMOR);
+       if (cpu_has_feature(CPU_FTR_ARCH_31)) {
+               sprs.dawr0 = mfspr(SPRN_DAWR0);
+               sprs.dawrx0 = mfspr(SPRN_DAWRX0);
+       }
 
        srr1 = isa300_idle_stop_mayloss(psscr);         /* go idle */
 
@@ -710,6 +716,10 @@ static unsigned long power9_idle_stop(unsigned long psscr, 
bool mmu_on)
                mtspr(SPRN_IAMR,        sprs.iamr);
                mtspr(SPRN_AMOR,        sprs.amor);
                mtspr(SPRN_UAMOR,       sprs.uamor);
+               if (cpu_has_feature(CPU_FTR_ARCH_31)) {
+                       mtspr(SPRN_DAWR0, sprs.dawr0);
+                       mtspr(SPRN_DAWRX0, sprs.dawrx0);
+               }
 
                /*
                 * Workaround for POWER9 DD2.0, if we lost resources, the ERAT
-- 
2.25.4