[PATCH v2 3/5] powerpc/powernv: Add winkle infrastructure

From: Shreyas B. Prabhu
Date: Wed Oct 01 2014 - 03:47:43 EST

Winkle causes power to be gated off to the entire chiplet. Hence the
hypervisor/firmware state in the entire chiplet is lost.

This patch adds necessary infrastructure to support waking up from
hypervisor state loss. Specifically does following:
- Before entering winkle, save state of registers that need to be
restored on wake up (SDR1, HFSCR)

- SRR1 bits 46:47 which is used to identify which power saving mode cpu
woke up from is '11' for both winkle and sleep. Hence introduce a flag
in PACA to distinguish b/w winkle and sleep.

- Upon waking up, restore all saved registers, recover slb

Cc: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>
Cc: Paul Mackerras <paulus@xxxxxxxxx>
Cc: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Cc: linuxppc-dev@xxxxxxxxxxxxxxxx
Suggested-by: Vaidyanathan Srinivasan <svaidy@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Shreyas B. Prabhu <shreyas@xxxxxxxxxxxxxxxxxx>
---
arch/powerpc/include/asm/machdep.h | 1 +
arch/powerpc/include/asm/paca.h | 3 ++
arch/powerpc/include/asm/ppc-opcode.h | 2 +
arch/powerpc/include/asm/processor.h | 2 +
arch/powerpc/kernel/asm-offsets.c | 1 +
arch/powerpc/kernel/exceptions-64s.S | 8 ++--
arch/powerpc/kernel/idle.c | 11 +++++
arch/powerpc/kernel/idle_power7.S | 81 +++++++++++++++++++++++++++++++++-
arch/powerpc/platforms/powernv/setup.c | 24 ++++++++++
9 files changed, 127 insertions(+), 6 deletions(-)

diff --git a/arch/powerpc/include/asm/machdep.h b/arch/powerpc/include/asm/machdep.h
index f37014f..0a3ced9 100644
--- a/arch/powerpc/include/asm/machdep.h
+++ b/arch/powerpc/include/asm/machdep.h
@@ -301,6 +301,7 @@ struct machdep_calls {
/* Idle handlers */
void (*setup_idle)(void);
unsigned long (*power7_sleep)(void);
+ unsigned long (*power7_winkle)(void);
};

extern void e500_idle(void);
diff --git a/arch/powerpc/include/asm/paca.h b/arch/powerpc/include/asm/paca.h
index a5139ea..3358f09 100644
--- a/arch/powerpc/include/asm/paca.h
+++ b/arch/powerpc/include/asm/paca.h
@@ -158,6 +158,9 @@ struct paca_struct {
* early exception handler for use by high level C handler
*/
struct opal_machine_check_event *opal_mc_evt;
+
+ /* Flag to distinguish b/w sleep and winkle */
+ u8 offline_state;
#endif
#ifdef CONFIG_PPC_BOOK3S_64
/* Exclusive emergency stack pointer for machine check exception. */
diff --git a/arch/powerpc/include/asm/ppc-opcode.h b/arch/powerpc/include/asm/ppc-opcode.h
index 6f85362..5155be7 100644
--- a/arch/powerpc/include/asm/ppc-opcode.h
+++ b/arch/powerpc/include/asm/ppc-opcode.h
@@ -194,6 +194,7 @@

#define PPC_INST_NAP 0x4c000364
#define PPC_INST_SLEEP 0x4c0003a4
+#define PPC_INST_WINKLE 0x4c0003e4

/* A2 specific instructions */
#define PPC_INST_ERATWE 0x7c0001a6
@@ -374,6 +375,7 @@

#define PPC_NAP stringify_in_c(.long PPC_INST_NAP)
#define PPC_SLEEP stringify_in_c(.long PPC_INST_SLEEP)
+#define PPC_WINKLE stringify_in_c(.long PPC_INST_WINKLE)

/* BHRB instructions */
#define PPC_CLRBHRB stringify_in_c(.long PPC_INST_CLRBHRB)
diff --git a/arch/powerpc/include/asm/processor.h b/arch/powerpc/include/asm/processor.h
index 41953cd..00e3df9 100644
--- a/arch/powerpc/include/asm/processor.h
+++ b/arch/powerpc/include/asm/processor.h
@@ -455,6 +455,8 @@ extern void arch_setup_idle(void);
extern void power7_nap(int check_irq);
extern unsigned long power7_sleep(void);
extern unsigned long __power7_sleep(void);
+extern unsigned long power7_winkle(void);
+extern unsigned long __power7_winkle(void);
extern void flush_instruction_cache(void);
extern void hard_reset_now(void);
extern void poweroff_now(void);
diff --git a/arch/powerpc/kernel/asm-offsets.c b/arch/powerpc/kernel/asm-offsets.c
index 9d7dede..ea98817 100644
--- a/arch/powerpc/kernel/asm-offsets.c
+++ b/arch/powerpc/kernel/asm-offsets.c
@@ -731,6 +731,7 @@ int main(void)
DEFINE(OPAL_MC_SRR0, offsetof(struct opal_machine_check_event, srr0));
DEFINE(OPAL_MC_SRR1, offsetof(struct opal_machine_check_event, srr1));
DEFINE(PACA_OPAL_MC_EVT, offsetof(struct paca_struct, opal_mc_evt));
+ DEFINE(PACAOFFLINESTATE, offsetof(struct paca_struct, offline_state));
#endif

return 0;
diff --git a/arch/powerpc/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S
index c64f3cc0..261f348 100644
--- a/arch/powerpc/kernel/exceptions-64s.S
+++ b/arch/powerpc/kernel/exceptions-64s.S
@@ -115,9 +115,7 @@ BEGIN_FTR_SECTION
#endif

/* Running native on arch 2.06 or later, check if we are
- * waking up from nap. We only handle no state loss and
- * supervisor state loss. We do -not- handle hypervisor
- * state loss at this time.
+ * waking up from power saving mode.
*/
mfspr r13,SPRN_SRR1
rlwinm. r13,r13,47-31,30,31
@@ -133,8 +131,8 @@ BEGIN_FTR_SECTION
b power7_wakeup_noloss
2: b power7_wakeup_loss

- /* Fast Sleep wakeup on PowerNV */
-8: b power7_wakeup_tb_loss
+ /* Fast Sleep / Winkle wakeup on PowerNV */
+8: b power7_wakeup_hv_state_loss

9:
END_FTR_SECTION_IFSET(CPU_FTR_HVMODE | CPU_FTR_ARCH_206)
diff --git a/arch/powerpc/kernel/idle.c b/arch/powerpc/kernel/idle.c
index 1f268e0..ed46217 100644
--- a/arch/powerpc/kernel/idle.c
+++ b/arch/powerpc/kernel/idle.c
@@ -98,6 +98,17 @@ unsigned long power7_sleep(void)
return ret;
}

+unsigned long power7_winkle(void)
+{
+ unsigned long ret;
+
+ if (ppc_md.power7_winkle)
+ ret = ppc_md.power7_winkle();
+ else
+ ret = __power7_winkle();
+ return ret;
+}
+
int powersave_nap;

#ifdef CONFIG_SYSCTL
diff --git a/arch/powerpc/kernel/idle_power7.S b/arch/powerpc/kernel/idle_power7.S
index c3481c9..87b2556 100644
--- a/arch/powerpc/kernel/idle_power7.S
+++ b/arch/powerpc/kernel/idle_power7.S
@@ -18,6 +18,13 @@
#include <asm/hw_irq.h>
#include <asm/kvm_book3s_asm.h>
#include <asm/opal.h>
+#include <asm/mmu-hash64.h>
+
+/*
+ * Use volatile GPRs' space to save essential SPRs before entering winkle
+ */
+#define _SDR1 GPR3
+#define _TSCR GPR4

#undef DEBUG

@@ -39,6 +46,7 @@
* Pass requested state in r3:
* 0 - nap
* 1 - sleep
+ * 2 - winkle
*
* To check IRQ_HAPPENED in r4
* 0 - don't check
@@ -109,9 +117,27 @@ _GLOBAL(power7_enter_nap_mode)
#endif
cmpwi cr0,r3,1
beq 2f
+ cmpwi cr0,r3,2
+ beq 3f
IDLE_STATE_ENTER_SEQ(PPC_NAP)
/* No return */
-2: IDLE_STATE_ENTER_SEQ(PPC_SLEEP)
+2:
+ li r4,1
+ stb r4,PACAOFFLINESTATE(r13)
+ IDLE_STATE_ENTER_SEQ(PPC_SLEEP)
+ /* No return */
+
+3:
+ mfspr r4,SPRN_SDR1
+ std r4,_SDR1(r1)
+
+ mfspr r4,SPRN_TSCR
+ std r4,_TSCR(r1)
+
+ /* Enter winkle */
+ li r4,0
+ stb r4,PACAOFFLINESTATE(r13)
+ IDLE_STATE_ENTER_SEQ(PPC_WINKLE)
/* No return */

_GLOBAL(power7_idle)
@@ -187,6 +213,59 @@ ALT_FTR_SECTION_END_NESTED_IFSET(CPU_FTR_ARCH_207S, 66); \
20: nop;


+_GLOBAL(__power7_winkle)
+ li r3,2
+ li r4,1
+ b power7_powersave_common
+ /* No return */
+
+_GLOBAL(power7_wakeup_hv_state_loss)
+ /* Check paca flag to diffentiate b/w fast sleep and winkle */
+ lbz r4,PACAOFFLINESTATE(13)
+ cmpwi cr0,r4,0
+ bne power7_wakeup_tb_loss
+
+ ld r2,PACATOC(r13);
+ ld r1,PACAR1(r13)
+
+ bl __restore_cpu_power8
+
+ /* Time base re-sync */
+ li r3,OPAL_RESYNC_TIMEBASE
+ bl opal_call_realmode;
+
+ /* Restore SLB from PACA */
+ ld r8,PACA_SLBSHADOWPTR(r13)
+
+ .rept SLB_NUM_BOLTED
+ li r3, SLBSHADOW_SAVEAREA
+ LDX_BE r5, r8, r3
+ addi r3, r3, 8
+ LDX_BE r6, r8, r3
+ andis. r7,r5,SLB_ESID_V@h
+ beq 1f
+ slbmte r6,r5
+1: addi r8,r8,16
+ .endr
+
+ ld r4,_SDR1(r1)
+ mtspr SPRN_SDR1,r4
+
+ ld r4,_TSCR(r1)
+ mtspr SPRN_TSCR,r4
+
+ 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_tb_loss)
ld r2,PACATOC(r13);
ld r1,PACAR1(r13)
diff --git a/arch/powerpc/platforms/powernv/setup.c b/arch/powerpc/platforms/powernv/setup.c
index 9d9a898..f45b52d 100644
--- a/arch/powerpc/platforms/powernv/setup.c
+++ b/arch/powerpc/platforms/powernv/setup.c
@@ -370,6 +370,29 @@ static unsigned long pnv_power7_sleep(void)
return srr1;
}

+/*
+ * We need to keep track of offline cpus also for calling
+ * fastsleep workaround appropriately
+ */
+static unsigned long pnv_power7_winkle(void)
+{
+ int cpu, primary_thread;
+ unsigned long srr1;
+
+ cpu = smp_processor_id();
+ primary_thread = cpu_first_thread_sibling(cpu);
+
+ if (need_fastsleep_workaround) {
+ pnv_apply_fastsleep_workaround(1, primary_thread);
+ srr1 = __power7_winkle();
+ pnv_apply_fastsleep_workaround(0, primary_thread);
+ } else {
+ srr1 = __power7_winkle();
+ }
+ return srr1;
+}
+
+
static void __init pnv_setup_machdep_opal(void)
{
ppc_md.get_boot_time = opal_get_boot_time;
@@ -384,6 +407,7 @@ static void __init pnv_setup_machdep_opal(void)
ppc_md.handle_hmi_exception = opal_handle_hmi_exception;
ppc_md.setup_idle = pnv_setup_idle;
ppc_md.power7_sleep = pnv_power7_sleep;
+ ppc_md.power7_winkle = pnv_power7_winkle;
}

#ifdef CONFIG_PPC_POWERNV_RTAS
--
1.9.3

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