Subject: [PATCH 1/3] arm64: Add cpuidle context save/restore helpers

From: Marc Zyngier <[email-masked]>
Date: Tue, 8 Jun 2021 18:27:13 +0100

As we need to start doing some additional work on all idle
paths, let's introduce a set of macros that will perform
the work related to the GICv3 pseudo-NMI idle entry exit.

Stubs are introduced to 32bit ARM for compatibility.
As these helpers are currently unused, the is no functional
change.

Signed-off-by: Marc Zyngier <[email-masked]>
---
 arch/arm/include/asm/cpuidle.h   |  5 +++++
 arch/arm64/include/asm/cpuidle.h | 35 ++++++++++++++++++++++++++++++++
 2 files changed, 40 insertions(+)

diff --git a/arch/arm/include/asm/cpuidle.h b/arch/arm/include/asm/cpuidle.h
index 0d67ed682e07..1e0b8da12d96 100644
--- a/arch/arm/include/asm/cpuidle.h
+++ b/arch/arm/include/asm/cpuidle.h
@@ -49,4 +49,9 @@ extern int arm_cpuidle_suspend(int index);
 
 extern int arm_cpuidle_init(int cpu);
 
+struct arm_cpuidle_context { };
+
+#define arm_cpuidle_save_context(c)	(void)c
+#define arm_cpuidle_restore_context(c)	(void)c
+
 #endif
diff --git a/arch/arm64/include/asm/cpuidle.h b/arch/arm64/include/asm/cpuidle.h
index 3c5ddb429ea2..53adad0a5c7e 100644
--- a/arch/arm64/include/asm/cpuidle.h
+++ b/arch/arm64/include/asm/cpuidle.h
@@ -18,4 +18,39 @@ static inline int arm_cpuidle_suspend(int index)
 	return -EOPNOTSUPP;
 }
 #endif
+
+#ifdef CONFIG_ARM64_PSEUDO_NMI
+#include <asm/arch_gicv3.h>
+
+struct arm_cpuidle_context {
+	unsigned long pmr;
+	unsigned long daif_bits;
+};
+
+#define arm_cpuidle_save_context(__c)					\
+	do {								\
+		struct arm_cpuidle_context *c = __c;			\
+		if (system_uses_irq_prio_masking()) {			\
+			c->daif_bits = read_sysreg(daif);		\
+			write_sysreg(c->daif_bits | PSR_I_BIT | PSR_F_BIT, \
+				     daif);				\
+			c->pmr = gic_read_pmr();			\
+			gic_write_pmr(GIC_PRIO_IRQON | GIC_PRIO_PSR_I_SET); \
+		}							\
+	} while (0)
+
+#define arm_cpuidle_restore_context(__c)				\
+	do {								\
+		struct arm_cpuidle_context *c = __c;			\
+		if (system_uses_irq_prio_masking()) {			\
+			gic_write_pmr(c->pmr);				\
+			write_sysreg(c->daif_bits, daif);		\
+		}							\
+	} while (0)
+#else
+struct arm_cpuidle_context { };
+
+#define arm_cpuidle_save_context(c)	(void)c
+#define arm_cpuidle_restore_context(c)	(void)c
+#endif
 #endif
-- 
2.30.2

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