linux-kernel - [RFC 2/3] Demonstration of handling an idle-stop quirk version

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Message-Id: <4084fa08404fbf65942a08335318b6d800d363fc.1583332695.git.psampat@linux.ibm.com>
Date:   Wed,  4 Mar 2020 21:31:22 +0530
From:   Pratik Rajesh Sampat <psampat@...ux.ibm.com>
To:     linuxppc-dev@...abs.org, linux-kernel@...r.kernel.org,
        mpe@...erman.id.au, mikey@...ling.org, npiggin@...il.com,
        vaidy@...ux.ibm.com, ego@...ux.vnet.ibm.com,
        skiboot@...ts.ozlabs.org, oohall@...il.com, psampat@...ux.ibm.com,
        pratik.r.sampat@...il.com
Subject: [RFC 2/3] Demonstration of handling an idle-stop quirk version

Concept patch demonstrating an idle-stop version discovery from the
device tree, along with population its support and versioning. It also
assigns the function pointer to handle any idle-stop specific quirks.

Signed-off-by: Pratik Rajesh Sampat <psampat@...ux.ibm.com>
---
 arch/powerpc/include/asm/processor.h  |  1 +
 arch/powerpc/kernel/dt_cpu_ftrs.c     | 16 ++++++++++++++++
 arch/powerpc/platforms/powernv/idle.c |  8 ++++++++
 3 files changed, 25 insertions(+)

diff --git a/arch/powerpc/include/asm/processor.h b/arch/powerpc/include/asm/processor.h
index da59f01a5c09..277dbabafd02 100644
--- a/arch/powerpc/include/asm/processor.h
+++ b/arch/powerpc/include/asm/processor.h
@@ -432,6 +432,7 @@ enum idle_boot_override {IDLE_NO_OVERRIDE = 0, IDLE_POWERSAVE_OFF};
 #define STOP_ENABLE		0x00000001
 
 #define STOP_VERSION_P9       0x1
+#define STOP_VERSION_P9_V1    0x2
 
 /*
  * Classify the dependencies of the stop states
diff --git a/arch/powerpc/kernel/dt_cpu_ftrs.c b/arch/powerpc/kernel/dt_cpu_ftrs.c
index db1a525e090d..63e30aa49356 100644
--- a/arch/powerpc/kernel/dt_cpu_ftrs.c
+++ b/arch/powerpc/kernel/dt_cpu_ftrs.c
@@ -298,6 +298,21 @@ static int __init feat_enable_idle_stop(struct dt_cpu_feature *f)
 	return 1;
 }
 
+static int __init feat_enable_idle_stop_quirk(struct dt_cpu_feature *f)
+{
+	u64 lpcr;
+
+	/* Set PECE wakeup modes for ISAv3.0B */
+	lpcr = mfspr(SPRN_LPCR);
+	lpcr |=  LPCR_PECE0;
+	lpcr |=  LPCR_PECE1;
+	lpcr |=  LPCR_PECE2;
+	mtspr(SPRN_LPCR, lpcr);
+	stop_dep.cpuidle_prop |= STOP_ENABLE;
+	stop_dep.stop_version = STOP_VERSION_P9_V1;
+
+	return 1;
+}
 static int __init feat_enable_mmu_hash(struct dt_cpu_feature *f)
 {
 	u64 lpcr;
@@ -592,6 +607,7 @@ static struct dt_cpu_feature_match __initdata
 	{"idle-nap", feat_enable_idle_nap, 0},
 	{"alignment-interrupt-dsisr", feat_enable_align_dsisr, 0},
 	{"idle-stop", feat_enable_idle_stop, 0},
+	{"idle-stop-v1", feat_enable_idle_stop_quirk, 0},
 	{"machine-check-power8", feat_enable_mce_power8, 0},
 	{"performance-monitor-power8", feat_enable_pmu_power8, 0},
 	{"data-stream-control-register", feat_enable_dscr, CPU_FTR_DSCR},
diff --git a/arch/powerpc/platforms/powernv/idle.c b/arch/powerpc/platforms/powernv/idle.c
index c32cdc37acf4..9f5b21da2fc5 100644
--- a/arch/powerpc/platforms/powernv/idle.c
+++ b/arch/powerpc/platforms/powernv/idle.c
@@ -805,6 +805,11 @@ static unsigned long power9_idle_stop(unsigned long psscr, bool mmu_on)
 	return srr1;
 }
 
+static unsigned long power9_idle_quirky_stop(unsigned long psscr, bool mmu_on)
+{
+	return power9_idle_stop(psscr, mmu_on);
+}
+
 #ifdef CONFIG_HOTPLUG_CPU
 static unsigned long power9_offline_stop(unsigned long psscr)
 {
@@ -1360,6 +1365,9 @@ static int __init pnv_init_idle_states(void)
 	case STOP_VERSION_P9:
 		stop_dep.idle_stop = power9_idle_stop;
 		break;
+	case STOP_VERSION_P9_V1:
+		stop_dep.idle_stop = power9_idle_quirky_stop;
+		break;
 	default:
 		stop_dep.idle_stop = NULL;
 		goto out;
-- 
2.24.1