Move private APIs in gic_common.h to a private header

This patch moves the private GIC common accessors from `gic_common.h` to
a new private header file `gic_common_private.h`. This patch also adds
additional comments to GIC register accessors to highlight the fact
that some of them access register values that correspond to multiple
interrupt IDs. The convention used is that the `set`, `get` and `clr`
accessors access and modify the values corresponding to a single interrupt
ID whereas the `read` and `write` GIC register accessors access the raw
GIC registers and it could correspond to multiple interrupt IDs depending
on the register accessed.

Change-Id: I2643ecb2533f01e3d3219fcedfb5f80c120622f9
diff --git a/drivers/arm/gic/v3/gicv3_private.h b/drivers/arm/gic/v3/gicv3_private.h
index c8b311a..5e2409f 100644
--- a/drivers/arm/gic/v3/gicv3_private.h
+++ b/drivers/arm/gic/v3/gicv3_private.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2015, ARM Limited and Contributors. All rights reserved.
+ * Copyright (c) 2015-2016, ARM Limited and Contributors. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are met:
@@ -84,16 +84,24 @@
 	 ((typer_val >> 32) & 0xffffff))
 
 /*******************************************************************************
- * Private function prototypes
+ * Private GICv3 function prototypes for accessing entire registers.
+ * Note: The raw register values correspond to multiple interrupt IDs and
+ * the number of interrupt IDs involved depends on the register accessed.
  ******************************************************************************/
 unsigned int gicd_read_igrpmodr(uintptr_t base, unsigned int id);
 unsigned int gicr_read_ipriorityr(uintptr_t base, unsigned int id);
+void gicd_write_igrpmodr(uintptr_t base, unsigned int id, unsigned int val);
+void gicr_write_ipriorityr(uintptr_t base, unsigned int id, unsigned int val);
+
+/*******************************************************************************
+ * Private GICv3 function prototypes for accessing the GIC registers
+ * corresponding to a single interrupt ID. These functions use bitwise
+ * operations or appropriate register accesses to modify or return
+ * the bit-field corresponding the single interrupt ID.
+ ******************************************************************************/
 unsigned int gicd_get_igrpmodr(uintptr_t base, unsigned int id);
 unsigned int gicr_get_igrpmodr0(uintptr_t base, unsigned int id);
 unsigned int gicr_get_igroupr0(uintptr_t base, unsigned int id);
-unsigned int gicv3_get_pending_grp1_interrupt_id(unsigned int pending_grp);
-void gicd_write_igrpmodr(uintptr_t base, unsigned int id, unsigned int val);
-void gicr_write_ipriorityr(uintptr_t base, unsigned int id, unsigned int val);
 void gicd_set_igrpmodr(uintptr_t base, unsigned int id);
 void gicr_set_igrpmodr0(uintptr_t base, unsigned int id);
 void gicr_set_isenabler0(uintptr_t base, unsigned int id);
@@ -101,6 +109,11 @@
 void gicd_clr_igrpmodr(uintptr_t base, unsigned int id);
 void gicr_clr_igrpmodr0(uintptr_t base, unsigned int id);
 void gicr_clr_igroupr0(uintptr_t base, unsigned int id);
+void gicr_set_ipriorityr(uintptr_t base, unsigned int id, unsigned int pri);
+
+/*******************************************************************************
+ * Private GICv3 helper function prototypes
+ ******************************************************************************/
 void gicv3_spis_configure_defaults(uintptr_t gicd_base);
 void gicv3_ppi_sgi_configure_defaults(uintptr_t gicr_base);
 void gicv3_secure_spis_configure(uintptr_t gicd_base,
@@ -179,6 +192,11 @@
 	mmio_write_32(base + GICR_WAKER, val);
 }
 
+/*******************************************************************************
+ * GIC Re-distributor functions for accessing entire registers.
+ * Note: The raw register values correspond to multiple interrupt IDs and
+ * the number of interrupt IDs involved depends on the register accessed.
+ ******************************************************************************/
 static inline unsigned int gicr_read_icenabler0(uintptr_t base)
 {
 	return mmio_read_32(base + GICR_ICENABLER0);