[boot-wrapper PATCH v3 6/8] gic-v3: Prepare for gicv3 with EL2

[Jaxson Han]

This is a preparation for allowing boot-wrapper configuring the gicv3
with EL2.

When confiuring with EL2, since there is no ICC_CTLR_EL2, the
ICC_CTLR_EL3 cannot be replaced with ICC_CTLR_EL2 simply.
See [https://developer.arm.com/documentation/ihi0069/latest/].

As the caller, gic_secure_init expects the ICC_CTLR to be written,
we change the function into gic_init_icc_ctlr(). In the GIC spec,
the r/w bits in this register ([6:0]) either affect EL3 IRQ routing
(not applicable since no EL3), non-secure IRQ handling (not applicable
since only secure state in Armv8-R aarch64), or are aliased to
ICC_CTLR_EL1 bits.
So, based on this, the new gic_init_icc_ctlr() would be:
When currentEL is EL3, init ICC_CTLR_EL3 as before.
When currentEL is not EL3, init ICC_CTLR_EL1 with ICC_CTLR_EL1_RESET.

Signed-off-by: Jaxson Han <jaxson.han at arm.com>
Reviewed-by: Andre Przywara <andre.przywara at arm.com>
---
 arch/aarch32/include/asm/gic-v3.h |  7 ++++++
 arch/aarch64/include/asm/gic-v3.h | 38 ++++++++++++++++++++++++++++---
 gic-v3.c                          |  2 +-
 3 files changed, 43 insertions(+), 4 deletions(-)

diff --git a/arch/aarch32/include/asm/gic-v3.h b/arch/aarch32/include/asm/gic-v3.h
index ec9a327..86abe09 100644
--- a/arch/aarch32/include/asm/gic-v3.h
+++ b/arch/aarch32/include/asm/gic-v3.h
@@ -9,6 +9,8 @@
 #ifndef __ASM_AARCH32_GICV3_H
 #define __ASM_AARCH32_GICV3_H
 
+#define ICC_CTLR_RESET	(0UL)
+
 static inline uint32_t gic_read_icc_sre(void)
 {
 	uint32_t val;
@@ -26,4 +28,9 @@ static inline void gic_write_icc_ctlr(uint32_t val)
 	asm volatile ("mcr p15, 6, %0, c12, c12, 4" : : "r" (val));
 }
 
+static inline void gic_init_icc_ctlr()
+{
+	gic_write_icc_ctlr(ICC_CTLR_RESET);
+}
+
 #endif
diff --git a/arch/aarch64/include/asm/gic-v3.h b/arch/aarch64/include/asm/gic-v3.h
index e743c02..b3dfbd3 100644
--- a/arch/aarch64/include/asm/gic-v3.h
+++ b/arch/aarch64/include/asm/gic-v3.h
@@ -15,21 +15,53 @@
 #define ICC_CTLR_EL3	"S3_6_C12_C12_4"
 #define ICC_PMR_EL1	"S3_0_C4_C6_0"
 
+#define ICC_CTLR_EL3_RESET	(0UL)
+#define ICC_CTLR_EL1_RESET	(0UL)
+
+static inline uint32_t current_el(void)
+{
+	uint32_t val;
+
+	asm volatile ("mrs %0, CurrentEL" : "=r" (val));
+	return val;
+}
+
 static inline uint32_t gic_read_icc_sre(void)
 {
 	uint32_t val;
-	asm volatile ("mrs %0, " ICC_SRE_EL3 : "=r" (val));
+
+	if(current_el() == CURRENTEL_EL3)
+		asm volatile ("mrs %0, " ICC_SRE_EL3 : "=r" (val));
+	else
+		asm volatile ("mrs %0, " ICC_SRE_EL2 : "=r" (val));
+
 	return val;
 }
 
 static inline void gic_write_icc_sre(uint32_t val)
 {
-	asm volatile ("msr " ICC_SRE_EL3 ", %0" : : "r" (val));
+	if(current_el() == CURRENTEL_EL3)
+		asm volatile ("msr " ICC_SRE_EL3 ", %0" : : "r" (val));
+	else
+		asm volatile ("msr " ICC_SRE_EL2 ", %0" : : "r" (val));
 }
 
-static inline void gic_write_icc_ctlr(uint32_t val)
+static inline void gic_write_icc_ctlr_el3(uint32_t val)
 {
 	asm volatile ("msr " ICC_CTLR_EL3 ", %0" : : "r" (val));
 }
 
+static inline void gic_write_icc_ctlr_el1(uint32_t val)
+{
+	asm volatile ("msr " ICC_CTLR_EL1 ", %0" : : "r" (val));
+}
+
+static inline void gic_init_icc_ctlr()
+{
+	if(current_el() == CURRENTEL_EL3)
+		gic_write_icc_ctlr_el3(ICC_CTLR_EL3_RESET);
+	else
+		gic_write_icc_ctlr_el1(ICC_CTLR_EL1_RESET);
+}
+
 #endif
diff --git a/gic-v3.c b/gic-v3.c
index ae2d2bc..4850572 100644
--- a/gic-v3.c
+++ b/gic-v3.c
@@ -121,6 +121,6 @@ void gic_secure_init(void)
 	gic_write_icc_sre(sre);
 	isb();
 
-	gic_write_icc_ctlr(0);
+	gic_init_icc_ctlr();
 	isb();
 }
-- 
2.25.1