[PATCH v2 2/5] firmware: Add common FW_FDT_PATH compile-time option

[Anup Patel]

Currently, only FW_PAYLOAD has mechanism to embed external
FDT using FW_PAYLOAD_FDT_PATH compile-time option.

This patch adds a common FW_FDT_PATH compile-time option to
embed external FDT for all OpenSBI firmwares (i.e FW_JUMP,
FW_PAYLOAD, and FW_DYNAMIC).

Signed-off-by: Anup Patel <anup.patel at wdc.com>
Reviewed-by: Atish Patra <atish.patra at wdc.com>
---
 docs/firmware/fw.md       | 16 +++++++++++-----
 firmware/external_deps.mk |  4 ++++
 firmware/fw_base.S        | 16 ++++++++++++++++
 firmware/objects.mk       |  7 +++++++
 4 files changed, 38 insertions(+), 5 deletions(-)

diff --git a/docs/firmware/fw.md b/docs/firmware/fw.md
index 4133c23..cc0cc9e 100644
--- a/docs/firmware/fw.md
+++ b/docs/firmware/fw.md
@@ -51,11 +51,17 @@ case, a *FW_PAYLOAD* firmware allows embedding a flattened device tree in the
 Firmware Configuration and Compilation
 --------------------------------------
 
-All firmware types mandate the definition of the following compile time
-configuration parameter.
-
-* **FW_TEXT_ADDR** - Defines the address at which the previous booting stage
-  loads OpenSBI firmware.
+All firmware types support the following common compile time configuration
+parameters:
+
+* **FW_TEXT_ADDR** - Defines the execution address of the OpenSBI firmware.
+  This configuration parameter is mandatory.
+* **FW_FDT_PATH** - Path to an external flattened device tree binary file to
+  be embedded in the *.rodata* section of the final firmware. If this option
+  is not provided then the firmware will expect the FDT to be passed as an
+  argument by the prior booting stage.
+* **FW_FDT_PADDING** - Optional zero bytes padding to the embedded flattened
+  device tree binary file specified by **FW_FDT_PATH** option.
 
 Additionally, each firmware type as a set of type specific configuration
 parameters. Detailed information for each firmware type can be found in the
diff --git a/firmware/external_deps.mk b/firmware/external_deps.mk
index 2b8f9f6..f43ac06 100644
--- a/firmware/external_deps.mk
+++ b/firmware/external_deps.mk
@@ -7,5 +7,9 @@
 #   Anup Patel <anup.patel at wdc.com>
 #
 
+$(platform_build_dir)/firmware/fw_dynamic.o: $(FW_FDT_PATH)
+$(platform_build_dir)/firmware/fw_jump.o: $(FW_FDT_PATH)
+$(platform_build_dir)/firmware/fw_payload.o: $(FW_FDT_PATH)
+
 $(platform_build_dir)/firmware/fw_payload.o: $(FW_PAYLOAD_PATH_FINAL)
 $(platform_build_dir)/firmware/fw_payload.o: $(FW_PAYLOAD_FDT_PATH)
diff --git a/firmware/fw_base.S b/firmware/fw_base.S
index 0271d9a..95197da 100644
--- a/firmware/fw_base.S
+++ b/firmware/fw_base.S
@@ -182,6 +182,11 @@ _bss_zero:
 	call	fw_save_info
 	MOV_5R	a0, s0, a1, s1, a2, s2, a3, s3, a4, s4
 
+#ifdef FW_FDT_PATH
+	/* Override previous arg1 */
+	la	a1, fw_fdt_bin
+#endif
+
 	/* Override previous arg1 */
 	MOV_3R	s0, a0, s1, a1, s2, a2
 	call	fw_prev_arg1
@@ -668,3 +673,14 @@ _reset_regs:
 	csrw CSR_MSCRATCH, 0
 
 	ret
+
+#ifdef FW_FDT_PATH
+	.section .rodata
+	.align 4
+	.globl fw_fdt_bin
+fw_fdt_bin:
+	.incbin FW_FDT_PATH
+#ifdef FW_FDT_PADDING
+	.fill FW_FDT_PADDING, 1, 0
+#endif
+#endif
diff --git a/firmware/objects.mk b/firmware/objects.mk
index c980362..2eea54c 100644
--- a/firmware/objects.mk
+++ b/firmware/objects.mk
@@ -17,6 +17,13 @@ ifdef FW_TEXT_START
 firmware-genflags-y += -DFW_TEXT_START=$(FW_TEXT_START)
 endif
 
+ifdef FW_FDT_PATH
+firmware-genflags-y += -DFW_FDT_PATH=\"$(FW_FDT_PATH)\"
+ifdef FW_FDT_PADDING
+firmware-genflags-y += -DFW_FDT_PADDING=$(FW_FDT_PADDING)
+endif
+endif
+
 firmware-bins-$(FW_DYNAMIC) += fw_dynamic.bin
 
 firmware-bins-$(FW_JUMP) += fw_jump.bin
-- 
2.25.1