irqchip/gic-v3: Add support for Range Selector (RS) feature

A new feature Range Selector (RS) has been added to GIC specification
in order to support more than 16 CPUs at affinity level 0. New fields
are introduced in SGI system registers (ICC_SGI0R_EL1, ICC_SGI1R_EL1
and ICC_ASGI1R_EL1) to relax an artificial limit of 16 at level 0.

- A new RSS field in ICC_CTLR_EL3, ICC_CTLR_EL1 and ICV_CTLR_EL1:
  [18] - Range Selector Support (RSS)
  0b0 = Targeted SGIs with affinity level 0 values of 0-15 are supported.
  0b1 = Targeted SGIs with affinity level 0 values of 0-255 are supported.

- A new RS field in ICC_SGI0R_EL1, ICC_SGI1R_EL1 and ICC_ASGI1R_EL1:
  [47:44] - RangeSelector (RS) which group of 16 TargetList[n] field
            TargetList[n] represents aff0 value ((RS*16)+n)
            When ICC_CTLR_EL3.RSS==0 or ICC_CTLR_EL1.RSS==0, RS is RES0.

- A new RSS field in GICD_TYPER:
  [26] - Range Selector Support (RSS)
  0b0 = Targeted SGIs with affinity level 0 values of 0-15 are supported.
  0b1 = Targeted SGIs with affinity level 0 values of 0-255 are supported.

Signed-off-by: Shanker Donthineni <shankerd@codeaurora.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>

1 files changed, 5 insertions, 0 deletions

diff --git a/arch/arm64/include/asm/arch_gicv3.h b/arch/arm64/include/asm/arch_gicv3.h
index b7e3f74822da..9becba9ab392 100644
--- a/arch/arm64/include/asm/arch_gicv3.h
+++ b/arch/arm64/include/asm/arch_gicv3.h
@@ -87,6 +87,11 @@ static inline void gic_write_ctlr(u32 val)
 	isb();
 }
 
+static inline u32 gic_read_ctlr(void)
+{
+	return read_sysreg_s(SYS_ICC_CTLR_EL1);
+}
+
 static inline void gic_write_grpen1(u32 val)
 {
 	write_sysreg_s(val, SYS_ICC_IGRPEN1_EL1);