Added serv and made a blinky testbench for it

sw/blinky/Makefile

@@ -0,0 +1,14 @@
+TOOLCHAIN_PREFIX?=riscv64-elf-
+CC=$(TOOLCHAIN_PREFIX)gcc
+OBJCOPY=$(TOOLCHAIN_PREFIX)objcopy
+
+%.elf: %.S link.ld
+# 	$(CC) -nostartfiles -nostdlib -march=rv32i_zicsr -mabi=ilp32 -Tlink.ld -o$@ $<
+	$(CC) -nostartfiles -nostdlib -ffreestanding -march=rv32i_zicsr -mabi=ilp32 -Tlink.ld -o$@ $<
+%.bin: %.elf
+	$(OBJCOPY) -O binary $< $@
+%.hex: %.bin
+	hexdump -v -e '1/1 "%02x\n"' $< > $@
+
+clean:
+	rm -f *.elf *.bin *.hex

sw/blinky/blinky.S

@@ -0,0 +1,17 @@
+#define GPIO_BASE 0x80000000
+#define DELAY 100
+
+.globl _start
+_start:
+	lui a0, %hi(GPIO_BASE)
+	addi a0, a0, %lo(GPIO_BASE)
+	addi t0, zero, 0
+	li t1, DELAY
+.lp1:
+	sb t0, 0(a0)
+	addi t0, t0, 1
+	and t2, zero, zero
+time1:
+	addi t2, t2, 1
+	bne t1, t2, time1
+	j .lp1

sw/blinky/blinky.hex

@@ -0,0 +1,40 @@
+37
+05
+00
+80
+13
+05
+05
+00
+93
+02
+00
+00
+13
+03
+40
+06
+23
+00
+55
+00
+93
+82
+12
+00
+b3
+73
+00
+00
+93
+83
+13
+00
+e3
+1e
+73
+fe
+6f
+f0
+df
+fe

sw/blinky/link.ld

@@ -0,0 +1,10 @@
+OUTPUT_ARCH( "riscv" )
+ENTRY(_start)
+
+SECTIONS
+{
+  . = 0x00000000;
+  .text : { *(.text) }
+  .data : { *(.data) }
+  .bss : { *(.bss) }
+}