locks: bakery: use is_dcache_enabled() helper

bakery_lock_normal.c uses the raw register accessor, read_sctlr(_el3)
to check whether the dcache is enabled.

Using is_dcache_enabled() is cleaner, and a good abstraction for
the library code like this.

A problem is is_dcache_enabled() is declared in the local header,
lib/xlat_tables_v2/xlat_tables_private.h

I searched for a good place to declare this helper. Moving it to
arch_helpers.h, closed to cache operation helpers, looks good enough
to me.

I also changed the type of 'is_cached' to bool for consistency,
and to avoid MISRA warnings.

Change-Id: I9b016f67bc8eade25c316aa9c0db0fa4cd375b79
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
diff --git a/lib/locks/bakery/bakery_lock_normal.c b/lib/locks/bakery/bakery_lock_normal.c
index 0605fce..7d35dea 100644
--- a/lib/locks/bakery/bakery_lock_normal.c
+++ b/lib/locks/bakery/bakery_lock_normal.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2015-2018, ARM Limited and Contributors. All rights reserved.
+ * Copyright (c) 2015-2020, ARM Limited and Contributors. All rights reserved.
  * Copyright (c) 2020, NVIDIA Corporation. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
@@ -84,7 +84,7 @@
 
 /* Helper function to check if the lock is acquired */
 static inline bool is_lock_acquired(const bakery_info_t *my_bakery_info,
-							int is_cached)
+				    bool is_cached)
 {
 	/*
 	 * Even though lock data is updated only by the owning cpu and
@@ -99,7 +99,7 @@
 }
 
 static unsigned int bakery_get_ticket(bakery_lock_t *lock,
-						unsigned int me, int is_cached)
+				      unsigned int me, bool is_cached)
 {
 	unsigned int my_ticket, their_ticket;
 	unsigned int they;
@@ -164,17 +164,14 @@
 
 void bakery_lock_get(bakery_lock_t *lock)
 {
-	unsigned int they, me, is_cached;
+	unsigned int they, me;
 	unsigned int my_ticket, my_prio, their_ticket;
 	bakery_info_t *their_bakery_info;
 	unsigned int their_bakery_data;
+	bool is_cached;
 
 	me = plat_my_core_pos();
-#ifdef __aarch64__
-	is_cached = read_sctlr_el3() & SCTLR_C_BIT;
-#else
-	is_cached = read_sctlr() & SCTLR_C_BIT;
-#endif
+	is_cached = is_dcache_enabled();
 
 	/* Get a ticket */
 	my_ticket = bakery_get_ticket(lock, me, is_cached);
@@ -232,11 +229,7 @@
 void bakery_lock_release(bakery_lock_t *lock)
 {
 	bakery_info_t *my_bakery_info;
-#ifdef __aarch64__
-	unsigned int is_cached = read_sctlr_el3() & SCTLR_C_BIT;
-#else
-	unsigned int is_cached = read_sctlr() & SCTLR_C_BIT;
-#endif
+	bool is_cached = is_dcache_enabled();
 
 	my_bakery_info = get_bakery_info(plat_my_core_pos(), lock);