Working SERV cpu

sw/.gitignore

@@ -0,0 +1,8 @@
+*.o
+*.hex
+*.bin
+*.map
+*.elf.asm
+*.elf
+*.coe
+*.mif

sw/blinky/Makefile

@@ -1,14 +1,56 @@
-TOOLCHAIN_PREFIX?=riscv64-elf-
-CC=$(TOOLCHAIN_PREFIX)gcc
-OBJCOPY=$(TOOLCHAIN_PREFIX)objcopy
+TOOLCHAIN_PREFIX ?= riscv64-elf-
 
-%.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
+CC      := $(TOOLCHAIN_PREFIX)gcc
+OBJCOPY := $(TOOLCHAIN_PREFIX)objcopy
+OBJDUMP := $(TOOLCHAIN_PREFIX)objdump
+SIZE    := $(TOOLCHAIN_PREFIX)size
+
+TARGET  := blinky
+SRCS_C  := blinky.c
+SRCS_S  := start.s
+OBJS    := $(SRCS_C:.c=.o) $(SRCS_S:.s=.o)
+
+ARCH_FLAGS := -march=rv32i_zicsr -mabi=ilp32
+CFLAGS     := $(ARCH_FLAGS) -Os -ffreestanding -fno-builtin -Wall -Wextra
+ASFLAGS    := $(ARCH_FLAGS)
+LDFLAGS    := $(ARCH_FLAGS) -nostdlib -nostartfiles -Wl,-Bstatic,-Tlink.ld,--gc-sections,-Map,$(TARGET).map
+
+HEX_TO_COE := ../../scripts/hex_to_coe.py
+HEX_TO_MIF := ../../scripts/hex_to_mif.py
+
+.PHONY: all clean disasm size
+
+all: $(TARGET).elf $(TARGET).bin $(TARGET).hex $(TARGET).coe $(TARGET).mif $(TARGET).elf.asm
+
+$(TARGET).elf: $(OBJS) link.ld
+	$(CC) $(LDFLAGS) -o $@ $(OBJS)
+
+%.o: %.c
+	$(CC) $(CFLAGS) -c -o $@ $<
+
+%.o: %.s
+	$(CC) $(ASFLAGS) -c -o $@ $<
+
+$(TARGET).bin: $(TARGET).elf
 	$(OBJCOPY) -O binary $< $@
-%.hex: %.bin
+
+$(TARGET).hex: $(TARGET).bin
 	hexdump -v -e '1/1 "%02x\n"' $< > $@
 
+$(TARGET).coe: $(TARGET).hex
+	$(HEX_TO_COE) $< $@
+
+$(TARGET).mif: $(TARGET).hex
+	$(HEX_TO_MIF) $< $@
+
+$(TARGET).elf.asm: $(TARGET).elf
+	$(OBJDUMP) -d -S $< > $@
+
+disasm: $(TARGET).elf.asm
+
+size: $(TARGET).elf
+	$(SIZE) $<
+
 clean:
-	rm -f *.elf *.bin *.hex
+	rm -f $(TARGET).elf $(TARGET).bin $(TARGET).hex $(TARGET).coe $(TARGET).mif \
+		$(TARGET).elf.asm $(TARGET).map $(OBJS)

sw/blinky/blinky.S

@@ -1,17 +0,0 @@
-#define GPIO_BASE 0x80000000
-#define DELAY 2
-
-.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.c

@@ -0,0 +1,22 @@
+#include <stdint.h>
+
+#define GPIO_BASE 0x40000000u
+
+static volatile uint32_t * const gpio = (volatile uint32_t *)GPIO_BASE;
+
+static void delay(volatile uint32_t ticks){
+    while (ticks--) {
+        __asm__ volatile ("nop");
+    }
+}
+
+int main(void)
+{
+    uint32_t v = 0;
+
+    for (;;) {
+        *gpio = v;
+        v++;
+        delay(20000u);
+    }
+}

sw/blinky/link.ld

@@ -1,10 +1,33 @@
-OUTPUT_ARCH( "riscv" )
+OUTPUT_ARCH("riscv")
 ENTRY(_start)
 
+MEMORY
+{
+  RAM (rwx) : ORIGIN = 0x00000000, LENGTH = 8K
+}
+
 SECTIONS
 {
-  . = 0x00000000;
-  .text : { *(.text) }
-  .data : { *(.data) }
-  .bss : { *(.bss) }
+  .text :
+  {
+    KEEP(*(.text.init))
+    *(.text .text.*)
+    *(.rodata .rodata.*)
+  } > RAM
+
+  .data :
+  {
+    *(.data .data.*)
+  } > RAM
+
+  .bss (NOLOAD) :
+  {
+    __bss_start = .;
+    *(.bss .bss.*)
+    *(COMMON)
+    __bss_end = .;
+  } > RAM
+
+  . = ALIGN(4);
+  __stack_top = ORIGIN(RAM) + LENGTH(RAM);
 }

sw/blinky/start.s

@@ -0,0 +1,23 @@
+.section .text.init
+.globl _start
+.type _start, @function
+
+_start:
+    la sp, __stack_top
+
+    # Zero .bss
+    la t0, __bss_start
+    la t1, __bss_end
+1:
+    bgeu t0, t1, 2f
+    sw zero, 0(t0)
+    addi t0, t0, 4
+    j 1b
+
+2:
+    call main
+
+3:
+    j 3b
+
+.size _start, .-_start