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Linus Torvalds1da177e2005-04-16 15:20:36 -07001/* $Id: head.S,v 1.7 2003/09/01 17:58:19 lethal Exp $
2 *
3 * arch/sh/kernel/head.S
4 *
5 * Copyright (C) 1999, 2000 Niibe Yutaka & Kaz Kojima
6 *
7 * This file is subject to the terms and conditions of the GNU General Public
8 * License. See the file "COPYING" in the main directory of this archive
9 * for more details.
10 *
11 * Head.S contains the SH exception handlers and startup code.
12 */
13#include <linux/linkage.h>
Paul Mundtd153ea82006-09-27 18:20:16 +090014#include <asm/thread_info.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070015
Paul Mundtb7e108e2006-09-27 15:00:04 +090016#ifdef CONFIG_CPU_SH4A
17#define SYNCO() synco
18
19#define PREFI(label, reg) \
20 mov.l label, reg; \
21 prefi @reg
22#else
23#define SYNCO()
24#define PREFI(label, reg)
25#endif
26
Linus Torvalds1da177e2005-04-16 15:20:36 -070027 .section .empty_zero_page, "aw"
28ENTRY(empty_zero_page)
29 .long 1 /* MOUNT_ROOT_RDONLY */
30 .long 0 /* RAMDISK_FLAGS */
31 .long 0x0200 /* ORIG_ROOT_DEV */
32 .long 1 /* LOADER_TYPE */
Paul Mundt972ad0e2008-05-13 17:41:46 +090033 .long 0x00000000 /* INITRD_START */
34 .long 0x00000000 /* INITRD_SIZE */
Stuart Menefy7a2eacb2007-11-26 21:29:09 +090035#ifdef CONFIG_32BIT
36 .long 0x53453f00 + 32 /* "SE?" = 32 bit */
37#else
38 .long 0x53453f00 + 29 /* "SE?" = 29 bit */
39#endif
Paul Mundte2dfb912006-12-12 08:53:29 +0900401:
41 .skip PAGE_SIZE - empty_zero_page - 1b
Linus Torvalds1da177e2005-04-16 15:20:36 -070042
Paul Mundt339547b2007-07-20 17:40:03 +090043 .section .text.head, "ax"
44
Linus Torvalds1da177e2005-04-16 15:20:36 -070045/*
46 * Condition at the entry of _stext:
47 *
48 * BSC has already been initialized.
49 * INTC may or may not be initialized.
50 * VBR may or may not be initialized.
51 * MMU may or may not be initialized.
52 * Cache may or may not be initialized.
53 * Hardware (including on-chip modules) may or may not be initialized.
54 *
55 */
56ENTRY(_stext)
57 ! Initialize Status Register
58 mov.l 1f, r0 ! MD=1, RB=0, BL=0, IMASK=0xF
59 ldc r0, sr
60 ! Initialize global interrupt mask
Yoshinori Satode398402006-11-05 16:15:19 +090061#ifdef CONFIG_CPU_HAS_SR_RB
Paul Mundtaba10302007-09-21 18:32:32 +090062 mov #0, r0
Linus Torvalds1da177e2005-04-16 15:20:36 -070063 ldc r0, r6_bank
Yoshinori Satode398402006-11-05 16:15:19 +090064#endif
65
Paul Mundtb7e108e2006-09-27 15:00:04 +090066 /*
67 * Prefetch if possible to reduce cache miss penalty.
68 *
69 * We do this early on for SH-4A as a micro-optimization,
70 * as later on we will have speculative execution enabled
71 * and this will become less of an issue.
72 */
73 PREFI(5f, r0)
74 PREFI(6f, r0)
75
Linus Torvalds1da177e2005-04-16 15:20:36 -070076 !
77 mov.l 2f, r0
78 mov r0, r15 ! Set initial r15 (stack pointer)
Yoshinori Satode398402006-11-05 16:15:19 +090079#ifdef CONFIG_CPU_HAS_SR_RB
Paul Mundtaba10302007-09-21 18:32:32 +090080 mov.l 7f, r0
Linus Torvalds1da177e2005-04-16 15:20:36 -070081 ldc r0, r7_bank ! ... and initial thread_info
Yoshinori Satode398402006-11-05 16:15:19 +090082#endif
Paul Mundt740a3e62008-12-17 15:33:43 +090083
84#ifndef CONFIG_SH_NO_BSS_INIT
85 /*
86 * Don't clear BSS if running on slow platforms such as an RTL simulation,
87 * remote memory via SHdebug link, etc. For these the memory can be guaranteed
88 * to be all zero on boot anyway.
89 */
90 ! Clear BSS area
Paul Mundtaba10302007-09-21 18:32:32 +090091#ifdef CONFIG_SMP
92 mov.l 3f, r0
93 cmp/eq #0, r0 ! skip clear if set to zero
94 bt 10f
95#endif
96
Linus Torvalds1da177e2005-04-16 15:20:36 -070097 mov.l 3f, r1
98 add #4, r1
99 mov.l 4f, r2
100 mov #0, r0
1019: cmp/hs r2, r1
102 bf/s 9b ! while (r1 < r2)
103 mov.l r0,@-r2
Paul Mundtb7e108e2006-09-27 15:00:04 +0900104
Paul Mundtaba10302007-09-21 18:32:32 +090010510:
Paul Mundt740a3e62008-12-17 15:33:43 +0900106#endif
107
Paul Mundtb7e108e2006-09-27 15:00:04 +0900108 ! Additional CPU initialization
109 mov.l 6f, r0
110 jsr @r0
111 nop
112
113 SYNCO() ! Wait for pending instructions..
Paul Mundtaba10302007-09-21 18:32:32 +0900114
Linus Torvalds1da177e2005-04-16 15:20:36 -0700115 ! Start kernel
116 mov.l 5f, r0
117 jmp @r0
118 nop
119
120 .balign 4
Yoshinori Satode398402006-11-05 16:15:19 +0900121#if defined(CONFIG_CPU_SH2)
1221: .long 0x000000F0 ! IMASK=0xF
123#else
Linus Torvalds1da177e2005-04-16 15:20:36 -07001241: .long 0x400080F0 ! MD=1, RB=0, BL=0, FD=1, IMASK=0xF
Yoshinori Satode398402006-11-05 16:15:19 +0900125#endif
Paul Mundtaba10302007-09-21 18:32:32 +0900126ENTRY(stack_start)
Paul Mundtd153ea82006-09-27 18:20:16 +09001272: .long init_thread_union+THREAD_SIZE
Linus Torvalds1da177e2005-04-16 15:20:36 -07001283: .long __bss_start
1294: .long _end
1305: .long start_kernel
1316: .long sh_cpu_init
Paul Mundtaba10302007-09-21 18:32:32 +09001327: .long init_thread_union