rpi3: Add mem reserve region to DTB if present

When a device tree blob is present at a known address, instead of, for
example, relying on the user modifying the Linux command line to warn
about the memory reserved for the Trusted Firmware, pass it on the DTB.

The current code deletes the memory reserved for the default bootstrap
of the Raspberry Pi and adds the region used by the Trusted Firmware.

This system replaces the previous one consisting on adding
``memmap=16M$256M`` to the Linux command line. It's also meant to be
used by U-Boot and any other bootloader that understands DTB files.

Change-Id: I13ee528475fb043d6e8d9e9f24228e37ac3ac436
Signed-off-by: Antonio Nino Diaz <antonio.ninodiaz@arm.com>

3 files changed, 83 insertions, 12 deletions

diff --git a/plat/rpi3/platform.mk b/plat/rpi3/platform.mk
index a7b0991fb..36c1ee2b4 100644
--- a/plat/rpi3/platform.mk
+++ b/plat/rpi3/platform.mk
@@ -4,12 +4,16 @@
 # SPDX-License-Identifier: BSD-3-Clause
 #
 
+include lib/libfdt/libfdt.mk
+include lib/xlat_tables_v2/xlat_tables.mk
+
 PLAT_INCLUDES		:=	-Iinclude/common/tbbr			\
 				-Iplat/rpi3/include
 
 PLAT_BL_COMMON_SOURCES	:=	drivers/console/aarch64/console.S	\
 				drivers/ti/uart/aarch64/16550_console.S	\
-				plat/rpi3/rpi3_common.c
+				plat/rpi3/rpi3_common.c			\
+				${XLAT_TABLES_LIB_SRCS}
 
 BL1_SOURCES		+=	drivers/io/io_fip.c			\
 				drivers/io/io_memmap.c			\
@@ -37,12 +41,8 @@ BL31_SOURCES		+=	lib/cpus/aarch64/cortex_a53.S		\
 				plat/rpi3/aarch64/plat_helpers.S	\
 				plat/rpi3/rpi3_bl31_setup.c		\
 				plat/rpi3/rpi3_pm.c			\
-				plat/rpi3/rpi3_topology.c
-
-# Translation tables library
-include lib/xlat_tables_v2/xlat_tables.mk
-
-PLAT_BL_COMMON_SOURCES	+=	${XLAT_TABLES_LIB_SRCS}
+				plat/rpi3/rpi3_topology.c		\
+				${LIBFDT_SRCS}
 
 # Tune compiler for Cortex-A53
 ifeq ($(notdir $(CC)),armclang)
diff --git a/plat/rpi3/rpi3_bl31_setup.c b/plat/rpi3/rpi3_bl31_setup.c
index 0ae783e12..483d150f0 100644
--- a/plat/rpi3/rpi3_bl31_setup.c
+++ b/plat/rpi3/rpi3_bl31_setup.c
@@ -6,6 +6,7 @@
 
 #include <assert.h>
 #include <bl_common.h>
+#include <libfdt.h>
 #include <platform.h>
 #include <platform_def.h>
 #include <xlat_mmu_helpers.h>
@@ -137,12 +138,74 @@ void bl31_plat_arch_setup(void)
 	enable_mmu_el3(0);
 }
 
-void bl31_platform_setup(void)
+/*
+ * Add information to the device tree (if any) about the reserved DRAM used by
+ * the Trusted Firmware.
+ */
+static void rpi3_dtb_add_mem_rsv(void)
 {
+	int i, regions, rc;
+	uint64_t addr, size;
+	void *dtb = (void *)RPI3_PRELOADED_DTB_BASE;
+
+	INFO("rpi3: Checking DTB...\n");
+
+	/* Return if no device tree is detected */
+	if (fdt_check_header(dtb) != 0)
+		return;
+
+	regions = fdt_num_mem_rsv(dtb);
+
+	VERBOSE("rpi3: Found %d mem reserve region(s)\n", regions);
+
+	/* We expect to find one reserved region that we can modify */
+	if (regions < 1)
+		return;
+
+	/*
+	 * Look for the region that corresponds to the default boot firmware. It
+	 * starts at address 0, and it is not needed when the default firmware
+	 * is replaced by this port of the Trusted Firmware.
+	 */
+	for (i = 0; i < regions; i++) {
+		if (fdt_get_mem_rsv(dtb, i, &addr, &size) != 0)
+			continue;
+
+		if (addr != 0x0)
+			continue;
+
+		VERBOSE("rpi3: Firmware mem reserve region found\n");
+
+		rc = fdt_del_mem_rsv(dtb, i);
+		if (rc != 0) {
+			INFO("rpi3: Can't remove mem reserve region (%d)\n", rc);
+		}
+
+		break;
+	}
+
+	if (i == regions) {
+		VERBOSE("rpi3: Firmware mem reserve region not found\n");
+	}
+
 	/*
-	 * Do initial security configuration to allow DRAM/device access
-	 * (if earlier BL has not already done so).
+	 * Reserve all SRAM. As said in the documentation, this isn't actually
+	 * secure memory, so it is needed to tell BL33 that this is a reserved
+	 * memory region. It doesn't guarantee it won't use it, though.
 	 */
+	rc = fdt_add_mem_rsv(dtb, SEC_SRAM_BASE, SEC_SRAM_SIZE);
+	if (rc != 0) {
+		WARN("rpi3: Can't add mem reserve region (%d)\n", rc);
+	}
+
+	INFO("rpi3: Reserved 0x%llx - 0x%llx in DTB\n", SEC_SRAM_BASE,
+	     SEC_SRAM_BASE + SEC_SRAM_SIZE);
+}
 
-	return;
+void bl31_platform_setup(void)
+{
+#ifdef RPI3_PRELOADED_DTB_BASE
+	/* Only modify a DTB if we know where to look for it */
+	rpi3_dtb_add_mem_rsv();
+#endif
 }
diff --git a/plat/rpi3/rpi3_common.c b/plat/rpi3/rpi3_common.c
index 98cf534c7..18ff1c82e 100644
--- a/plat/rpi3/rpi3_common.c
+++ b/plat/rpi3/rpi3_common.c
@@ -23,7 +23,12 @@
 
 #define MAP_SHARED_RAM	MAP_REGION_FLAT(SHARED_RAM_BASE,		\
 					SHARED_RAM_SIZE,		\
-					MT_DEVICE  | MT_RW | MT_SECURE)
+					MT_DEVICE | MT_RW | MT_SECURE)
+
+#ifdef RPI3_PRELOADED_DTB_BASE
+#define MAP_NS_DTB	MAP_REGION_FLAT(RPI3_PRELOADED_DTB_BASE, 0x10000, \
+					MT_MEMORY | MT_RW | MT_NS)
+#endif
 
 #define MAP_NS_DRAM0	MAP_REGION_FLAT(NS_DRAM0_BASE, NS_DRAM0_SIZE,	\
 					MT_MEMORY | MT_RW | MT_NS)
@@ -74,6 +79,9 @@ static const mmap_region_t plat_rpi3_mmap[] = {
 static const mmap_region_t plat_rpi3_mmap[] = {
 	MAP_SHARED_RAM,
 	MAP_DEVICE0,
+#ifdef RPI3_PRELOADED_DTB_BASE
+	MAP_NS_DTB,
+#endif
 #ifdef BL32_BASE
 	MAP_BL32_MEM,
 #endif