GIC: Add API to get interrupt active status

API documentation updated.

Change-Id: I6d61785af0d5330930c709de971a904dc7c3516c
Co-authored-by: Yousuf A <yousuf.sait@arm.com>
Signed-off-by: Jeenu Viswambharan <jeenu.viswambharan@arm.com>
diff --git a/drivers/arm/gic/v3/gicv3_helpers.c b/drivers/arm/gic/v3/gicv3_helpers.c
index 73ad060..81d50ad 100644
--- a/drivers/arm/gic/v3/gicv3_helpers.c
+++ b/drivers/arm/gic/v3/gicv3_helpers.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2015-2016, ARM Limited and Contributors. All rights reserved.
+ * Copyright (c) 2015-2017, ARM Limited and Contributors. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -172,6 +172,18 @@
 }
 
 /*
+ * Accessor to set the bit corresponding to interrupt ID in GIC Re-distributor
+ * ISACTIVER0.
+ */
+unsigned int gicr_get_isactiver0(uintptr_t base, unsigned int id)
+{
+	unsigned bit_num = id & ((1 << ISACTIVER_SHIFT) - 1);
+	unsigned int reg_val = gicr_read_isactiver0(base);
+
+	return (reg_val >> bit_num) & 0x1;
+}
+
+/*
  * Accessor to set the byte corresponding to interrupt ID
  * in GIC Re-distributor IPRIORITYR.
  */