Add support for setting memory contents during synthesis

bench/serv_wrapper.v

@@ -4,8 +4,7 @@ module serv_wrapper
  input wire  wb_clk,
  output wire q);
 
-   parameter memfile = "helloservice4000.hex";
-//   parameter memfile = "bitbang.hex";
+   parameter memfile = "zephyr_hello.hex";
 
    reg [4:0] rst_reg = 5'b11111;
 

rtl/serv_decode.v

@@ -78,7 +78,6 @@ module serv_decode
    wire      running;
    wire      mem_op;
    wire      shift_op;
-   wire      csr_op;
    wire      slt_op;
    wire      branch_op;
    wire      e_op;

serv.core

@@ -22,8 +22,8 @@ filesets:
 
   mem_files:
     files:
-      - bitbang.hex  : {copyto : bitbang.hex}
-      - helloservice4000.hex : {copyto : helloservice4000.hex}
+      - sw/blinky.hex       : {copyto : blinky.hex}
+      - sw/zephyr_hello.hex : {copyto : zephyr_hello.hex}
     file_type : user
       
   serv_top_tb:
@@ -65,6 +65,7 @@ targets:
   icebreaker:
     default_tool : icestorm
     filesets : [core, mem_files, wrapper, icebreaker]
+    parameters : [memfile]
     tools:
       icestorm:
         nextpnr_options: [--up5k, --freq, 12]
@@ -79,6 +80,7 @@ targets:
   tinyfpga_bx:
     default_tool : icestorm
     filesets : [core, mem_files, wrapper, tinyfpga_bx]
+    parameters : [memfile]
     tools:
       icestorm:
         nextpnr_options : [--lp8k, --package, cm81, --freq, 16]
@@ -120,8 +122,14 @@ parameters:
 
   firmware:
     datatype : file
+    description : Preload RAM with a hex file at runtime (overrides memfile)
     paramtype : plusarg
 
+  memfile:
+    datatype    : file
+    description : Preload RAM with a hex file at compile-time
+    paramtype   : vlogparam
+
   signature:
     datatype : file
     paramtype : plusarg

sw/Makefile

@@ -0,0 +1,9 @@
+%.elf: %.S
+	riscv64-unknown-elf-gcc -nostartfiles -march=rv32i -mabi=ilp32 -Tlink.ld -o$@ $<
+%.bin: %.elf
+	riscv64-unknown-elf-objcopy -O binary $< $@
+%.hex: %.bin
+	python3 makehex.py $< 2048 > $@
+
+clean:
+	rm -f *.elf *.bin *.hex

sw/blinky.S

@@ -0,0 +1,46 @@
+/*
+* LED Blinker
+* Assuming that GPIO_BASE is mapped to a GPIO core, which in turn is
+* connected to LEDs, this will light the LEDs one at a time.
+* Useful as smoke test to see that serv is running correctly
+*/
+#ifndef GPIO_BASE
+#define GPIO_BASE 0x40000000
+#endif
+
+#ifndef DELAY
+#define DELAY 0x100000 /* Loop 100000 times before inverting the LED */
+#endif
+	
+	/*
+	a0 = GPIO Base address
+	t0 = Value
+	t1 = Timer max value
+	t2 = Current timer value
+
+	*/
+
+.globl _start
+_start:
+	/* Load GPIO base address to a0 */
+	lui a0, %hi(GPIO_BASE)
+	addi a0, a0, %lo(GPIO_BASE)
+
+	/* Set timer value to control blink speed */
+	li t1, DELAY
+
+bl1:
+	/* Write to LEDs */
+	sb t0, 0(a0)
+
+	/* invert LED */
+	xori t0, t0, 1
+
+	/* Reset timer */
+	and t2, zero, zero
+
+	/* Delay loop */
+time1:
+	addi t2, t2, 1
+	bne t1, t2, time1
+	j bl1

sw/link.ld

@@ -0,0 +1,18 @@
+OUTPUT_ARCH( "riscv" )
+ENTRY(_start)
+
+SECTIONS
+{
+  . = 0x00000000;
+  .text.init : { *(.text.init) }
+  . = ALIGN(0x1000);
+  .tohost : { *(.tohost) }
+  . = ALIGN(0x1000);
+  .text : { *(.text) }
+  . = ALIGN(0x1000);
+  .data : { *(.data) }
+  .data.string : { *(.data.string)}
+  .bss : { *(.bss) }
+  _end = .;
+}
+

sw/makehex.py

@@ -0,0 +1,27 @@
+#!/usr/bin/env python3
+#
+# This is free and unencumbered software released into the public domain.
+#
+# Anyone is free to copy, modify, publish, use, compile, sell, or
+# distribute this software, either in source code form or as a compiled
+# binary, for any purpose, commercial or non-commercial, and by any
+# means.
+
+from sys import argv
+
+binfile = argv[1]
+nwords = int(argv[2])
+
+with open(binfile, "rb") as f:
+    bindata = f.read()
+
+assert len(bindata) < 4*nwords
+assert len(bindata) % 4 == 0
+
+for i in range(nwords):
+    if i < len(bindata) // 4:
+        w = bindata[4*i : 4*i+4]
+        print("%02x%02x%02x%02x" % (w[3], w[2], w[1], w[0]))
+    else:
+        print("0")
+