board: stm32mp1: use FDT address provided by TF-A at boot time

Save and use the FDT address provided by TF-A in r2 at boot time
(it is NT_FW_CONFIG = Non Trusted Firmware configuration file)

Address is saved in save_boot_params(), called by start.S
and the used DTB is gd->fdt_blob = board_fdt_blob_setup().

If dtb is not provided or invalid, U-Boot use as fallback
the builtin DTB.

Signed-off-by: Patrick Delaunay <patrick.delaunay@st.com>
Reviewed-by: Patrice Chotard <patrice.chotard@st.com>

2 files changed, 46 insertions, 0 deletions

diff --git a/arch/arm/mach-stm32mp/Makefile b/arch/arm/mach-stm32mp/Makefile
index eee39c27c3..2b8631d574 100644
--- a/arch/arm/mach-stm32mp/Makefile
+++ b/arch/arm/mach-stm32mp/Makefile
@@ -13,6 +13,7 @@ else
 obj-y += bsec.o
 obj-$(CONFIG_CMD_STM32KEY) += cmd_stm32key.o
 obj-$(CONFIG_ARMV7_PSCI) += psci.o
+obj-$(CONFIG_TFABOOT) += boot_params.o
 endif
 
 obj-$(CONFIG_$(SPL_)DM_REGULATOR) += pwr_regulator.o
diff --git a/arch/arm/mach-stm32mp/boot_params.c b/arch/arm/mach-stm32mp/boot_params.c
new file mode 100644
index 0000000000..e4351de939
--- /dev/null
+++ b/arch/arm/mach-stm32mp/boot_params.c
@@ -0,0 +1,45 @@
+// SPDX-License-Identifier: GPL-2.0+ OR BSD-3-Clause
+/*
+ * Copyright (C) 2019, STMicroelectronics - All Rights Reserved
+ */
+
+#include <common.h>
+#include <asm/sections.h>
+#include <asm/system.h>
+
+/*
+ * Force data-section, as .bss will not be valid
+ * when save_boot_params is invoked.
+ */
+static unsigned long nt_fw_dtb __section(".data");
+
+/*
+ * Save the FDT address provided by TF-A in r2 at boot time
+ * This function is called from start.S
+ */
+void save_boot_params(unsigned long r0, unsigned long r1, unsigned long r2,
+		      unsigned long r3)
+{
+	nt_fw_dtb = r2;
+
+	save_boot_params_ret();
+}
+
+/*
+ * Use the saved FDT address provided by TF-A at boot time (NT_FW_CONFIG =
+ * Non Trusted Firmware configuration file) when the pointer is valid
+ */
+void *board_fdt_blob_setup(void)
+{
+	debug("%s: nt_fw_dtb=%lx\n", __func__, nt_fw_dtb);
+
+	/* use external device tree only if address is valid */
+	if (nt_fw_dtb >= STM32_DDR_BASE) {
+		if (fdt_magic(nt_fw_dtb) == FDT_MAGIC)
+			return (void *)nt_fw_dtb;
+		debug("%s: DTB not found.\n", __func__);
+	}
+	debug("%s: fall back to builtin DTB, %p\n", __func__, &_end);
+
+	return (void *)&_end;
+}