From 0c1c117cf18ffa3fdc0342dfc47c6003fc5fc5a0 Mon Sep 17 00:00:00 2001
From: wdenk <wdenk>
Date: Wed, 30 Mar 2005 23:28:18 +0000
Subject: * Patch by Scott McNutt, 21 Oct 2004:   Add support for Nios-II EPCS
 Controller core.

* Patch by Scott McNutt, 20 Oct 2004:
  Nios-II cleanups:
  - Add sysid command (Nios-II only).
  - Locate default exception trampoline at proper offset.
  - Implement I/O routines (readb, writeb, etc)
  - Implement do_bootm_linux
---
 cpu/nios2/start.S | 29 +++++++++++++++++------------
 1 file changed, 17 insertions(+), 12 deletions(-)

(limited to 'cpu/nios2/start.S')

diff --git a/cpu/nios2/start.S b/cpu/nios2/start.S
index 281d42c..4c6e470 100644
--- a/cpu/nios2/start.S
+++ b/cpu/nios2/start.S
@@ -39,14 +39,24 @@ _start:
 	 * just be invalidating the cache a second time. If cache
 	 * is not implemented initi behaves as nop.
 	 */
-	movhi	r4, %hi(CFG_ICACHELINE_SIZE)
-	ori	r4, r4, %lo(CFG_ICACHELINE_SIZE)
+	ori	r4, r0, %lo(CFG_ICACHELINE_SIZE)
 	movhi	r5, %hi(CFG_ICACHE_SIZE)
 	ori	r5, r5, %lo(CFG_ICACHE_SIZE)
 	mov	r6, r0
 0:	initi	r6
 	add	r6, r6, r4
 	bltu	r6, r5, 0b
+	br	_except_end	/* Skip the tramp */
+
+	/* EXCEPTION TRAMPOLINE -- the following gets copied
+	 * to the exception address (below), but is otherwise at the
+	 * default exception vector offset (0x0020).
+	 */
+_except_start:
+	movhi	et, %hi(_exception)
+	ori	et, et, %lo(_exception)
+	jmp	et
+_except_end:
 
 	/* INTERRUPTS -- for now, all interrupts masked and globally
 	 * disabled.
@@ -117,7 +127,9 @@ _cur:	movhi	r5, %hi(_cur - _start)
 _reloc:
 
 	/* COPY EXCEPTION TRAMPOLINE -- copy the tramp to the
-	 * exception address.
+	 * exception address. Define CONFIG_ROM_STUBS to prevent
+	 * the copy (e.g. exception in flash or in other
+	 * softare/firmware component).
 	 */
 #if !defined(CONFIG_ROM_STUBS)
 	movhi	r4, %hi(_except_start)
@@ -126,12 +138,14 @@ _reloc:
 	ori	r5, r5, %lo(_except_end)
 	movhi	r6, %hi(CFG_EXCEPTION_ADDR)
 	ori	r6, r6, %lo(CFG_EXCEPTION_ADDR)
+	beq	r4, r6, 7f	/* Skip if at proper addr */
 
 6:	ldwio	r7, 0(r4)
 	stwio	r7, 0(r6)
 	addi	r4, r4, 4
 	addi	r6, r6, 4
 	bne	r4, r5, 6b
+7:
 #endif
 
 	/* STACK INIT -- zero top two words for call back chain.
@@ -155,15 +169,6 @@ _reloc:
 	 */
 	br	_start
 
-	/* EXCEPTION TRAMPOLINE -- the following gets copied
-	 * to the exception address.
-	 */
-_except_start:
-	movhi	et, %hi(_exception)
-	ori	et, et, %lo(_exception)
-	jmp	et
-_except_end:
-
 
 /*
  * dly_clks -- Nios2 (like Nios1) doesn't have a timebase in
-- 
cgit v1.1