tools: add bootrom

Signed-off-by: liangkangnan <liangkangnan@163.com>

tools/bootrom/.gitignore

@@ -0,0 +1,6 @@
+# Object files
+*.o
+*.bin
+*.elf
+*.mem
+*.dump

tools/bootrom/Makefile

@@ -0,0 +1,19 @@
+target := bootrom
+
+BIN2MEM := ../BinToMem.py
+
+RISCV_TOOLS_PATH := /opt/riscv32/bin
+RISCV_TOOLS_PREFIX := riscv32-unknown-elf-
+
+GCC?=$(abspath $(RISCV_TOOLS_PATH)/$(RISCV_TOOLS_PREFIX)gcc)
+OBJCOPY?=$(abspath $(RISCV_TOOLS_PATH)/$(RISCV_TOOLS_PREFIX)objcopy)
+OBJDUMP?=$(abspath $(RISCV_TOOLS_PATH)/$(RISCV_TOOLS_PREFIX)objdump)
+
+all:
+	$(GCC) -Tlink.ld bootrom.S -march=rv32im -mabi=ilp32 -mcmodel=medlow -nostartfiles -nostdlib -static -Wl,--no-gc-sections -o $(target).elf
+	$(OBJCOPY) -O binary $(target).elf $(target).bin
+	$(OBJDUMP) -d $(target).elf --disassemble-all --disassemble-zeroes --section=.text --section=.text.startup --section=.text.init --section=.data  > $(target).dump
+	$(BIN2MEM) $(target).bin $(target).mem
+
+clean:
+	rm -f *.img *.dump *.bin *.sv *.elf *.mem

tools/bootrom/README.md

@@ -0,0 +1,10 @@
+Bootrom源码。
+
+当从外部Flash启动时，需要先从此Bootrom启动（做一些初始化操作），然后通过Bootrom跳转到Flash地址空间，执行用户程序。
+
+编译：
+
+```
+make
+```
+

tools/bootrom/bootrom.S

@@ -0,0 +1,10 @@
+
+    .global entry
+    .option norvc
+entry:
+    lui	    a0, 0x0200
+    slli	a0, a0, 0x4
+    // jump to 0x02000000
+    jalr	a0
+loop:
+    j loop

tools/bootrom/link.ld

@@ -0,0 +1,11 @@
+OUTPUT_ARCH( "riscv" )
+ENTRY( entry )
+SECTIONS
+{
+    . = 0x01000000;
+    .text :
+    {
+        *(.text)
+    }
+    _end = .;
+}