firmware: Add fw_dynamic firmware

This patch provides first-cut implementation of fw_dynamic firmware.

As compared to fw_jump and fw_payload, the fw_dynamic obtains next
address, next mode and OpenSBI options from struct fw_dynamic_info.

The previous booting stage can create struct fw_dynamic_info in memory
and pass address of struct fw_dynamic_info in 'a2' register. Also, the
struct fw_dynamic_info has versioning as well so changes to the struct
fw_dynamic_info can be done in a backward compatible manner.

Signed-off-by: Anup Patel <anup.patel@wdc.com>
Reviewed-by: Atish Patra <atish.patra@wdc.com>

3 files changed, 136 insertions, 0 deletions

diff --git a/firmware/fw_dynamic.S b/firmware/fw_dynamic.S
new file mode 100644
index 0000000..cf97b60
--- /dev/null
+++ b/firmware/fw_dynamic.S
@@ -0,0 +1,118 @@
+/*
+ * SPDX-License-Identifier: BSD-2-Clause
+ *
+ * Copyright (c) 2019 Western Digital Corporation or its affiliates.
+ *
+ * Authors:
+ *   Anup Patel <anup.patel@wdc.com>
+ */
+
+#include <sbi/fw_dynamic.h>
+
+#include "fw_base.S"
+
+	.align 3
+	.section .entry, "ax", %progbits
+_bad_dynamic_info:
+	wfi
+	j	_bad_dynamic_info
+
+	.align 3
+	.section .entry, "ax", %progbits
+	.global fw_save_info
+	/*
+	 * We can only use a0, a1, a2, a3, and a4 registers here.
+	 * The a0, a1, and a2 registers will be same as passed by
+	 * previous booting stage.
+	 * Nothing to be returned here.
+	 */
+fw_save_info:
+	la	a4, _dynamic_next_arg1
+	REG_S	a1, (a4)
+	li	a4, FW_DYNAMIC_INFO_MAGIC_VALUE
+	REG_L	a3, FW_DYNAMIC_INFO_MAGIC_OFFSET(a2)
+	bne	a3, a4, _bad_dynamic_info
+	li	a4, FW_DYNAMIC_INFO_VERSION_MAX
+	REG_L	a3, FW_DYNAMIC_INFO_VERSION_OFFSET(a2)
+	bgt	a3, a4, _bad_dynamic_info
+	la	a4, _dynamic_next_addr
+	REG_L	a3, FW_DYNAMIC_INFO_NEXT_ADDR_OFFSET(a2)
+	REG_S	a3, (a4)
+	la	a4, _dynamic_next_mode
+	REG_L	a3, FW_DYNAMIC_INFO_NEXT_MODE_OFFSET(a2)
+	REG_S	a3, (a4)
+	la	a4, _dynamic_options
+	REG_L	a3, FW_DYNAMIC_INFO_OPTIONS_OFFSET(a2)
+	REG_S	a3, (a4)
+	ret
+
+	.align 3
+	.section .entry, "ax", %progbits
+	.global fw_prev_arg1
+	/*
+	 * We can only use a0, a1, and a2 registers here.
+	 * The previous arg1 should be returned in 'a0'.
+	 */
+fw_prev_arg1:
+	add	a0, zero, zero
+	ret
+
+	.align 3
+	.section .entry, "ax", %progbits
+	.global fw_next_arg1
+	/*
+	 * We can only use a0, a1, and a2 registers here.
+	 * The next arg1 should be returned in 'a0'.
+	 */
+fw_next_arg1:
+	la	a0, _dynamic_next_arg1
+	REG_L	a0, (a0)
+	ret
+
+	.align 3
+	.section .entry, "ax", %progbits
+	.global fw_next_addr
+	/*
+	 * We can only use a0, a1, and a2 registers here.
+	 * The next address should be returned in 'a0'.
+	 */
+fw_next_addr:
+	la	a0, _dynamic_next_addr
+	REG_L	a0, (a0)
+	ret
+
+	.align 3
+	.section .entry, "ax", %progbits
+	.global fw_next_mode
+	/*
+	 * We can only use a0, a1, and a2 registers here.
+	 * The next address should be returned in 'a0'
+	 */
+fw_next_mode:
+	la	a0, _dynamic_next_mode
+	REG_L	a0, (a0)
+	ret
+
+	.align 3
+	.section .entry, "ax", %progbits
+	.global fw_options
+	/*
+	 * We can only use a0, a1, and a2 registers here.
+	 * The 'a4' register will have default options.
+	 * The next address should be returned in 'a0'.
+	 */
+fw_options:
+	la	a0, _dynamic_options
+	REG_L	a0, (a0)
+	ret
+
+	.align 3
+	.section .entry, "ax", %progbits
+_dynamic_next_arg1:
+	RISCV_PTR 0x0
+_dynamic_next_addr:
+	RISCV_PTR 0x0
+_dynamic_next_mode:
+	RISCV_PTR PRV_S
+_dynamic_options:
+	RISCV_PTR 0x0
diff --git a/firmware/fw_dynamic.elf.ldS b/firmware/fw_dynamic.elf.ldS
new file mode 100644
index 0000000..7ee0787
--- /dev/null
+++ b/firmware/fw_dynamic.elf.ldS
@@ -0,0 +1,16 @@
+/*
+ * SPDX-License-Identifier: BSD-2-Clause
+ *
+ * Copyright (c) 2019 Western Digital Corporation or its affiliates.
+ *
+ * Authors:
+ *   Anup Patel <anup.patel@wdc.com>
+ */
+
+OUTPUT_ARCH(riscv)
+ENTRY(_start)
+
+SECTIONS
+{
+	#include "fw_base.ldS"
+}
diff --git a/firmware/objects.mk b/firmware/objects.mk
index cc38283..e8969e6 100644
--- a/firmware/objects.mk
+++ b/firmware/objects.mk
@@ -17,6 +17,8 @@ ifdef FW_TEXT_START
 firmware-genflags-y += -DFW_TEXT_START=$(FW_TEXT_START)
 endif
 
+firmware-bins-$(FW_DYNAMIC) += fw_dynamic.bin
+
 firmware-bins-$(FW_JUMP) += fw_jump.bin
 ifdef FW_JUMP_ADDR
 firmware-genflags-$(FW_JUMP) += -DFW_JUMP_ADDR=$(FW_JUMP_ADDR)