allwinner: Reserve and map space for the SCP firmware

The SCP firmware is allocated the last 16KiB of SRAM A2. This includes
the SCPI shared memory area, which must be mapped as MT_DEVICE to
prevent problems with cache coherency between the AP CPUs and the SCP.
For simplicity, map the whole SCP region as MT_DEVICE.
Signed-off-by: Samuel Holland <samuel@sholland.org>
Change-Id: Ie39eb5ff281b8898a3c1d9748dc08755f528e2f8

plat/allwinner/common/include/platform_def.h

@@ -14,7 +14,12 @@
 #include <sunxi_mmap.h>
 
 #define BL31_BASE			(SUNXI_SRAM_A2_BASE + 0x4000)
-#define BL31_LIMIT			(SUNXI_SRAM_A2_BASE + SUNXI_SRAM_A2_SIZE)
+#define BL31_LIMIT			(SUNXI_SRAM_A2_BASE + \
+					 SUNXI_SRAM_A2_SIZE - SUNXI_SCP_SIZE)
+
+/* The SCP firmware is allocated the last 16KiB of SRAM A2. */
+#define SUNXI_SCP_BASE			BL31_LIMIT
+#define SUNXI_SCP_SIZE			0x4000
 
 /* Overwrite U-Boot SPL, but reserve the first page for the SPL header. */
 #define BL31_NOBITS_BASE		(SUNXI_SRAM_A1_BASE + 0x1000)
@@ -51,7 +56,7 @@
 #define PLATFORM_CORE_COUNT		(PLATFORM_CLUSTER_COUNT * \
 					 PLATFORM_MAX_CPUS_PER_CLUSTER)
 #define PLATFORM_MAX_CPUS_PER_CLUSTER	U(4)
-#define PLATFORM_MMAP_REGIONS		4
+#define PLATFORM_MMAP_REGIONS		5
 #define PLATFORM_STACK_SIZE		(0x1000 / PLATFORM_CORE_COUNT)
 
 #ifndef SPD_none

plat/allwinner/common/sunxi_common.c

@@ -21,6 +21,8 @@
 static const mmap_region_t sunxi_mmap[PLATFORM_MMAP_REGIONS + 1] = {
 	MAP_REGION_FLAT(SUNXI_SRAM_BASE, SUNXI_SRAM_SIZE,
 			MT_RW_DATA | MT_SECURE),
+	MAP_REGION_FLAT(SUNXI_SCP_BASE, SUNXI_SCP_SIZE,
+			MT_DEVICE | MT_RW | MT_SECURE | MT_EXECUTE_NEVER),
 	MAP_REGION_FLAT(SUNXI_DEV_BASE, SUNXI_DEV_SIZE,
 			MT_DEVICE | MT_RW | MT_SECURE | MT_EXECUTE_NEVER),
 	MAP_REGION(SUNXI_DRAM_BASE, SUNXI_DRAM_VIRT_BASE, SUNXI_DRAM_SEC_SIZE,