[PATCH v3 18/21] RISC-V: add generic DT image

[Ahmad Fatoum]

This barebox image implements the same header as Linux and receives
the device tree in the same register. It can be booted from barebox
or loaded by Qemu -kernel option.

Signed-off-by: Ahmad Fatoum <a.fatoum at pengutronix.de>
---
 arch/riscv/Kconfig             |  9 +++++++++
 arch/riscv/boot/Makefile       |  1 +
 arch/riscv/boot/board-dt-2nd.c | 36 ++++++++++++++++++++++++++++++++++
 3 files changed, 46 insertions(+)
 create mode 100644 arch/riscv/boot/board-dt-2nd.c

diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index 08a0e7cef48d..e630ad4ceb98 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -73,6 +73,15 @@ config 64BIT
 
 source "arch/riscv/mach-erizo/Kconfig"
 
+config BOARD_RISCV_GENERIC_DT
+	select BOARD_GENERIC_DT
+	bool "Build generic RISC-V device tree 2nd stage image"
+	help
+	  This enables compilation of a generic image that can be started 2nd
+	  stage from barebox or from qemu. It picks up a device tree passed
+	  in a1 like the Kernel does, so it could be used anywhere where a Kernel
+	  image could be used. The image will be called images/barebox-dt-2nd.img
+
 endmenu
 
 menu "RISC-V specific settings"
diff --git a/arch/riscv/boot/Makefile b/arch/riscv/boot/Makefile
index 70e5b11bebb8..968a826d1620 100644
--- a/arch/riscv/boot/Makefile
+++ b/arch/riscv/boot/Makefile
@@ -1,3 +1,4 @@
 # SPDX-License-Identifier: GPL-2.0
 obj-y += start.o
 pbl-y += entry.o uncompress.o
+pbl-$(CONFIG_BOARD_GENERIC_DT) += board-dt-2nd.o
diff --git a/arch/riscv/boot/board-dt-2nd.c b/arch/riscv/boot/board-dt-2nd.c
new file mode 100644
index 000000000000..25fa7d4f2bef
--- /dev/null
+++ b/arch/riscv/boot/board-dt-2nd.c
@@ -0,0 +1,36 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <common.h>
+#include <debug_ll.h>
+#include <pbl.h>
+
+#if __riscv_xlen == 64
+#define IMAGE_LOAD_OFFSET 0x200000 /* Image load offset(2MB) from start of RAM */
+#else
+#define IMAGE_LOAD_OFFSET 0x400000 /* Image load offset(4MB) from start of RAM */
+#endif
+
+/* because we can depend on being loaded at an offset, we can just use
+ * our load address as stack top
+ */
+#define __barebox_riscv_head() \
+	__barebox_riscv_header("auipc sp, 0", IMAGE_LOAD_OFFSET, \
+			       RISCV_HEADER_VERSION, "RISCV", RISCV_IMAGE_MAGIC2)
+
+#include <asm/barebox-riscv.h>
+
+ENTRY_FUNCTION(start_dt_2nd, a0, _fdt, a2)
+{
+	unsigned long membase, memsize;
+	void *fdt = (void *)_fdt;
+
+	if (!fdt)
+		hang();
+
+	relocate_to_current_adr();
+	setup_c();
+
+	fdt_find_mem(fdt, &membase, &memsize);
+
+	barebox_riscv_entry(membase, memsize, fdt);
+}
-- 
2.29.2