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authorwdenk <wdenk>2005-03-30 23:28:18 +0000
committerwdenk <wdenk>2005-03-30 23:28:18 +0000
commit0c1c117cf18ffa3fdc0342dfc47c6003fc5fc5a0 (patch)
treeac60588bc373565ce7a626e39b3d149e715be025 /cpu/nios2/start.S
parent8f0b7cbe8027c3745f5e0a199ecd152b032d8ad0 (diff)
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* 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
Diffstat (limited to 'cpu/nios2/start.S')
-rw-r--r--cpu/nios2/start.S29
1 files changed, 17 insertions, 12 deletions
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