[Skiboot] [PATCH v2 6/6] core/cpu: move sleep/wake synchronisation out from low level code

[Nicholas Piggin]

The sleep/wake synchronisation involes the waker setting a wake
condition then testing if the target needs to be woken, vs setting
a wake-required flag then testing the wake condition. The low level
sleep state call comes after that.

This patch moves the synchronisation out from the low level sleep
functions and consolidates both copies into one place.

Signed-off-by: Nicholas Piggin <npiggin at gmail.com>
---
 core/cpu.c | 152 +++++++++++++++--------------------------------------
 1 file changed, 42 insertions(+), 110 deletions(-)

diff --git a/core/cpu.c b/core/cpu.c
index 2911b6f1c..95b780866 100644
--- a/core/cpu.c
+++ b/core/cpu.c
@@ -378,64 +378,21 @@ enum cpu_wake_cause {
 static unsigned int cpu_idle_p8(enum cpu_wake_cause wake_on)
 {
 	uint64_t lpcr = mfspr(SPR_LPCR) & ~SPR_LPCR_P8_PECE;
-	struct cpu_thread *cpu = this_cpu();
-	unsigned int vec = 0;
-
-	if (!pm_enabled) {
-		prlog_once(PR_DEBUG, "cpu_idle_p8 called pm disabled\n");
-		return vec;
-	}
+	unsigned int vec;
 
 	/* Clean up ICP, be ready for IPIs */
 	icp_prep_for_pm();
 
-	/* Mark outselves sleeping so wake ups know to send an IPI */
-	cpu->in_sleep = true;
-
-	/* Synchronize with wakers */
-	if (wake_on == cpu_wake_on_job) {
-		/* Mark ourselves in job sleep so queueing jobs send an IPI */
-		cpu->in_job_sleep = true;
-
-		/*
-		 * make stores to in_sleep and in_job_sleep visible before
-		 * checking jobs and testing reconfigure_idle
-		 */
-		sync();
-
-		/* Check for jobs again, of if PM got disabled */
-		if (cpu_check_jobs(cpu) || reconfigure_idle)
-			goto skip_sleep;
-
-		/* Setup wakup cause in LPCR: EE (for IPI) */
-		lpcr |= SPR_LPCR_P8_PECE2;
-		mtspr(SPR_LPCR, lpcr);
-
-	} else {
-		/*
-		 * make store to in_sleep visible before testing
-		 * reconfigure_idle
-		 */
-		sync();
-
-		/* Check if PM got disabled */
-		if (reconfigure_idle)
-			goto skip_sleep;
-
-		/* EE and DEC */
-		lpcr |= SPR_LPCR_P8_PECE2 | SPR_LPCR_P8_PECE3;
-		mtspr(SPR_LPCR, lpcr);
-	}
+	/* Setup wakup cause in LPCR: EE (for IPI) */
+	lpcr |= SPR_LPCR_P8_PECE2;
+	if (wake_on == cpu_wake_on_dec)
+		lpcr |= SPR_LPCR_P8_PECE3; /* DEC */
+	mtspr(SPR_LPCR, lpcr);
 	isync();
 
 	/* Enter nap */
 	vec = enter_p8_pm_state(false);
 
-skip_sleep:
-	/* Restore */
-	sync();
-	cpu->in_sleep = false;
-	cpu->in_job_sleep = false;
 	reset_cpu_icp();
 
 	return vec;
@@ -445,49 +402,11 @@ static unsigned int cpu_idle_p9(enum cpu_wake_cause wake_on)
 {
 	uint64_t lpcr = mfspr(SPR_LPCR) & ~SPR_LPCR_P9_PECE;
 	uint64_t psscr;
-	struct cpu_thread *cpu = this_cpu();
-	unsigned int vec = 0;
-
-	if (!pm_enabled) {
-		prlog(PR_DEBUG, "cpu_idle_p9 called on cpu 0x%04x with pm disabled\n", cpu->pir);
-		return vec;
-	}
-
-	/* Mark outselves sleeping so wake ups know to send an IPI */
-	cpu->in_sleep = true;
-
-	/* Synchronize with wakers */
-	if (wake_on == cpu_wake_on_job) {
-		/* Mark ourselves in job sleep so queueing jobs send an IPI */
-		cpu->in_job_sleep = true;
-
-		/*
-		 * make stores to in_sleep and in_job_sleep visible before
-		 * checking jobs and testing reconfigure_idle
-		 */
-		sync();
-
-		/* Check for jobs again, of if PM got disabled */
-		if (cpu_check_jobs(cpu) || reconfigure_idle)
-			goto skip_sleep;
-
-		/* HV DBELL for IPI */
-		lpcr |= SPR_LPCR_P9_PECEL1;
-	} else {
-		/*
-		 * make store to in_sleep visible before testing
-		 * reconfigure_idle
-		 */
-		sync();
-
-		/* Check if PM got disabled */
-		if (reconfigure_idle)
-			goto skip_sleep;
-
-		/* HV DBELL and DEC */
-		lpcr |= SPR_LPCR_P9_PECEL1 | SPR_LPCR_P9_PECEL3;
-	}
+	unsigned int vec;
 
+	lpcr |= SPR_LPCR_P9_PECEL1; /* HV DBELL for IPI */
+	if (wake_on == cpu_wake_on_dec)
+		lpcr |= SPR_LPCR_P9_PECEL3; /* DEC */
 	mtspr(SPR_LPCR, lpcr);
 	isync();
 
@@ -502,39 +421,46 @@ static unsigned int cpu_idle_p9(enum cpu_wake_cause wake_on)
 		/* PSSCR SD=0 ESL=0 EC=0 PSSL=0 TR=3 MTL=0 RL=1 */
 		psscr = PPC_BITMASK(54, 55) | PPC_BIT(63);
 		enter_p9_pm_lite_state(psscr);
+		vec = 0;
 	}
 
 	/* Clear doorbell */
 	p9_dbell_receive();
 
- skip_sleep:
-	/* Restore */
-	sync();
-	cpu->in_sleep = false;
-	cpu->in_job_sleep = false;
-
 	return vec;
 }
 
 static void cpu_idle_pm(enum cpu_wake_cause wake_on)
 {
+	struct cpu_thread *cpu = this_cpu();
 	unsigned int vec;
 
-	switch(proc_gen) {
-	case proc_gen_p8:
+	if (!pm_enabled) {
+		prlog_once(PR_DEBUG, "cpu_idle_pm called pm disabled\n");
+		return;
+	}
+
+	/*
+	 * Mark ourselves in sleep so other CPUs know to send an IPI,
+	 * then re-check the wake conditions. This is ordered against
+	 * queue_job_on_cpu() and reconfigure_idle_start() which first
+	 * set the wake conditions (either queue a job or set
+	 * reconfigure_idle = true), issue a sync(), then test if the
+	 * target is in_sleep / in_job_sleep.
+	 */
+	cpu->in_sleep = true;
+	if (wake_on == cpu_wake_on_job)
+		cpu->in_job_sleep = true;
+	sync();
+	if (reconfigure_idle)
+		goto skip_sleep;
+	if (wake_on == cpu_wake_on_job && cpu_check_jobs(cpu))
+		goto skip_sleep;
+
+	if (proc_gen == proc_gen_p8)
 		vec = cpu_idle_p8(wake_on);
-		break;
-	case proc_gen_p9:
-		vec = cpu_idle_p9(wake_on);
-		break;
-	case proc_gen_p10:
+	else
 		vec = cpu_idle_p9(wake_on);
-		break;
-	default:
-		vec = 0;
-		prlog_once(PR_DEBUG, "cpu_idle_pm called with bad processor type\n");
-		break;
-	}
 
 	if (vec == 0x100) {
 		unsigned long srr1 = mfspr(SPR_SRR1);
@@ -553,6 +479,12 @@ static void cpu_idle_pm(enum cpu_wake_cause wake_on)
 		enable_machine_check();
 		mtmsrd(MSR_RI, 1);
 	}
+
+skip_sleep:
+	sync();
+	cpu->in_sleep = false;
+	if (wake_on == cpu_wake_on_job)
+		cpu->in_job_sleep = false;
 }
 
 static struct lock idle_lock = LOCK_UNLOCKED;
-- 
2.23.0