Add U-Boot loader over MMU

x1/.gitignore

@@ -0,0 +1 @@
+c/uboot_bin.h

x1/Makefile

@@ -21,6 +21,15 @@ c/main.elf:
 c/main.bin: c/main.elf
 	@./extract.py c/main.elf $@
 
+c/uboot_loader.bin:
+	@if [ "$(UBOOT)" = "" ]; then \
+		echo "Please specify UBOOT."; \
+		exit 1; \
+	fi
+	@c/generate.py $(UBOOT) c/uboot_bin.h.tpl c/uboot_bin.h
+	@$(CC) -nostdlib -static -fPIC -marm -O0 c/start.S c/main_uboot.c -o c/uboot_loader.elf
+	@./extract.py c/uboot_loader.elf $@
+
 spray/main.bin:
 	@$(AS) spray/top.S
 	@./extract.py -p a.out spray/top.bin

x1/c/common.h

@@ -2,6 +2,7 @@
 
 #define readl(a) (*(volatile unsigned int *)(a))
 #define writel(v, a) (*(volatile unsigned int *)(a) = (v))
+#define writeb(v, a) (*(volatile unsigned char *)(a) = (v))
 
 typedef unsigned int u32;
 typedef unsigned short u16;

x1/c/generate.py

@@ -0,0 +1,27 @@
+#!/usr/bin/env python3
+import sys
+import textwrap
+
+
+def main():
+    if len(sys.argv) < 3:
+        print(f'Usage: {sys.argv[0]} u-boot.bin uboot_bin.h.tpl uboot_bin.h')
+
+    with open(sys.argv[2]) as f:
+        tpl = f.read()
+
+    with open(sys.argv[1], 'rb') as ui, open(sys.argv[3], 'w') as header:
+        uboot = ui.read()
+
+        out = ''
+        for i, b in enumerate(uboot):
+            out += f'{b:#04x}, '
+            if (i+1) % 16 == 0:
+                out = out.rstrip()
+                out += '\n'
+
+        formatted = tpl.format(uboot_size=len(uboot), uboot_bin=textwrap.indent(out, '    '))
+        header.write(formatted)
+
+
+main()

x1/c/main_uboot.c

@@ -0,0 +1,34 @@
+#include "common.h"
+#include "uboot_bin.h"
+
+#define VIRT_START (unsigned char *)0x8c000000
+
+void main() {
+    int i;
+    u8* ptr = VIRT_START;
+
+    // Turn off interrupts
+    asm volatile (
+        "cpsid if \n"
+    );
+
+    for (i=0; i<UBOOT_SIZE; i++) {
+        writeb(uboot_bin[i], ptr);
+        ptr++;
+    }
+
+    asm volatile (
+        "mrc p15, 0, r8, c14, c2, 1 \n"
+        "bic r8, r8, #1 \n"
+        "mcr p15, 0, r8, c14, c2, 1 \n"
+        "mrc p15, 0, r8, c14, c3, 1 \n"
+        "bic r8, r8, #1 \n"
+        "mcr p15, 0, r8, c14, c3, 1 \n"
+
+        "mrc p15, 0, r10, c1, c0, 0 \n"
+        "bic r10, r10, #1 \n"
+        "mcr p15, 0, r10, c1, c0, 0 \n"
+        "ldr r0, =0x60200000 \n"
+        "mov pc, r0"
+    );
+}

x1/c/uboot_bin.h.tpl

@@ -0,0 +1,5 @@
+#define UBOOT_SIZE {uboot_size}
+
+unsigned char uboot_bin[] = {{
+{uboot_bin}
+}};