irqchip/gicv3-its: Introduce two helper functions for accessing BASERn

This patch adds the two handy helper functions for reading and writing
ITS BASERn register.
Signed-off-by: NShanker Donthineni <shankerd@codeaurora.org>
[Marc: Folded its_write_baser_cache into its_write_baser]
Signed-off-by: NMarc Zyngier <marc.zyngier@arm.com>

drivers/irqchip/irq-gic-v3-its.c

@@ -824,6 +824,22 @@ static const char *its_base_type_string[] = {
 	[GITS_BASER_TYPE_RESERVED7] 	= "Reserved (7)",
 };
 
+static u64 its_read_baser(struct its_node *its, struct its_baser *baser)
+{
+	u32 idx = baser - its->tables;
+
+	return readq_relaxed(its->base + GITS_BASER + (idx << 3));
+}
+
+static void its_write_baser(struct its_node *its, struct its_baser *baser,
+			    u64 val)
+{
+	u32 idx = baser - its->tables;
+
+	writeq_relaxed(val, its->base + GITS_BASER + (idx << 3));
+	baser->val = its_read_baser(its, baser);
+}
+
 static void its_free_tables(struct its_node *its)
 {
 	int i;
@@ -863,7 +879,8 @@ static int its_alloc_tables(const char *node_name, struct its_node *its)
 	its->device_ids = ids;
 
 	for (i = 0; i < GITS_BASER_NR_REGS; i++) {
-		u64 val = readq_relaxed(its->base + GITS_BASER + i * 8);
+		struct its_baser *baser = its->tables + i;
+		u64 val = its_read_baser(its, baser);
 		u64 type = GITS_BASER_TYPE(val);
 		u64 entry_size = GITS_BASER_ENTRY_SIZE(val);
 		int order = get_order(psz);
@@ -937,10 +954,9 @@ static int its_alloc_tables(const char *node_name, struct its_node *its)
 		}
 
 		val |= alloc_pages - 1;
-		its->tables[i].val = val;
 
-		writeq_relaxed(val, its->base + GITS_BASER + i * 8);
-		tmp = readq_relaxed(its->base + GITS_BASER + i * 8);
+		its_write_baser_cache(its, baser, val);
+		tmp = baser->val;
 
 		if ((val ^ tmp) & GITS_BASER_SHAREABILITY_MASK) {
 			/*