From 70c8695eeeaae70b75ea3acc8174519980bed8ad Mon Sep 17 00:00:00 2001
From: Sean Cross <xobs@kosagi.com>
Date: Fri, 18 Jul 2014 18:41:14 +0800
Subject: [PATCH] fernvale: Relocate to PSRAM

Move execution from SPI to PSRAM, to fix 0xa0140000 problem.
---
 fernvale.ld |  2 +-
 start.S     | 62 +++++++++++++++++++++++++++++++++++++++++++++++++++--
 2 files changed, 61 insertions(+), 3 deletions(-)

diff --git a/fernvale.ld b/fernvale.ld
index 49ab75c..9cbe0c5 100644
--- a/fernvale.ld
+++ b/fernvale.ld
@@ -39,7 +39,7 @@ SECTIONS
 {
 	/* The OS entry point is here */
 
-	. = 0x10003460;
+	. = 0x20000; /* bootloader will copy data to this address */
 	.text : {
 		_stext = ABSOLUTE(.);
 		KEEP(*(vectors))
diff --git a/start.S b/start.S
index 1b2d31f..ad34384 100644
--- a/start.S
+++ b/start.S
@@ -1,4 +1,58 @@
 .section vectors
+
+.global reset
+reset:
+	mov	r0, #48
+	bl	uart_putc
+	mov	r0, #49
+	bl	uart_putc
+
+	ldr	r0, =0x7000cffc // stack_start
+	mov	sp, r0
+	mov	r2, #0xffffffff
+	ldr	r1, =0x7000c000 // stack_end
+
+clear_stack:
+	cmp	r1, r0
+	str	r2, [r0]
+	sub	r0, r0, #4
+	bcc	clear_stack
+
+	mov	r0, #66
+	bl	uart_putc
+
+# Copy 0x10000 bytes from =spi_offset to psram at 0x20000
+copy_code_to_ram:
+	mov	r0, #0x20000
+	ldr	r1, =0x10003460 // spi_offset
+	mov	r2, r1
+	mov	r3, #0x10000
+	add	r2, r2, r3
+
+copy_code_to_ram_loop:
+	cmp	r1, r2
+	ldrcc	r3, [r1], #4
+	strcc	r3, [r0], #4
+	bcc	copy_code_to_ram_loop
+	
+# Jump to main, which ought to be in psram now
+jump_to_main:
+	mov	r0, #69
+	bl	uart_putc
+
+	ldr	r0, =reset_handler
+	mov	pc, r0
+
+uart_putc:
+	ldr	r2, =0xa0080014 // uart offset
+uart_putc_ready_wait:
+	ldr	r1, [r2]
+	tst	r1, #0x20
+	beq	uart_putc_ready_wait
+	sub	r2, r2, #0x14
+	str	r0, [r2]
+	bx	lr
+
 .global rv_start
 rv_start:
 	b	do_reset
@@ -69,13 +123,17 @@ __udiv64:
 
 .global ram_memcpy
 ram_memcpy: 
-	ldr	pc, =ram_memcpy_addr
+	ldr	r0, =ram_memcpy_addr
+	ldr	r0, [r0]
+	mov	pc, r0
 ram_memcpy_addr:
         .long	0x70007388
 
 .global ram_bzero
 ram_bzero:
-	ldr	pc, =ram_bzero_addr
+	ldr	r0, =ram_bzero_addr
+	ldr	r0, [r0]
+	mov	pc, r0
 ram_bzero_addr:
         .long	0x700073bc