irqchip/GIC: Convert to EOImode == 1

So far, GICv2 has been used with EOImode == 0. The effect of this
mode is to perform the priority drop and the deactivation of the
interrupt at the same time.

While this works perfectly for Linux (we only have a single priority),
it causes issues when an interrupt is forwarded to a guest, and when
we want the guest to perform the EOI itself.

For this case, the GIC architecture provides EOImode == 1, where:
- A write to the EOI register drops the priority of the interrupt
  and leaves it active. Other interrupts at the same priority level
  can now be taken, but the active interrupt cannot be taken again
- A write to the DIR marks the interrupt as inactive, meaning it can
  now be taken again.

We only enable this feature when booted in HYP mode and that
the device-tree reported a suitable CPU interface. Observable behaviour
should remain unchanged.

Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Reviewed-and-tested-by: Eric Auger <eric.auger@linaro.org>
Cc: Christoffer Dall <christoffer.dall@linaro.org>
Cc: Jiang Liu <jiang.liu@linux.intel.com>
Cc: <linux-arm-kernel@lists.infradead.org>
Cc: kvmarm@lists.cs.columbia.edu
Cc: Jason Cooper <jason@lakedaemon.net>
Link: http://lkml.kernel.org/r/1440604845-28229-4-git-send-email-marc.zyngier@arm.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

1 files changed, 4 insertions, 0 deletions

diff --git a/include/linux/irqchip/arm-gic.h b/include/linux/irqchip/arm-gic.h
index 65da435d01c1..af3d29f70781 100644
--- a/include/linux/irqchip/arm-gic.h
+++ b/include/linux/irqchip/arm-gic.h
@@ -20,9 +20,13 @@
 #define GIC_CPU_ALIAS_BINPOINT		0x1c
 #define GIC_CPU_ACTIVEPRIO		0xd0
 #define GIC_CPU_IDENT			0xfc
+#define GIC_CPU_DEACTIVATE		0x1000
 
 #define GICC_ENABLE			0x1
 #define GICC_INT_PRI_THRESHOLD		0xf0
+
+#define GIC_CPU_CTRL_EOImodeNS		(1 << 9)
+
 #define GICC_IAR_INT_ID_MASK		0x3ff
 #define GICC_INT_SPURIOUS		1023
 #define GICC_DIS_BYPASS_MASK		0x1e0