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1da177e4 LT |
1 | /* $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 | */ | |
bbe215c2 | 13 | #include <linux/init.h> |
1da177e4 | 14 | #include <linux/linkage.h> |
d153ea88 | 15 | #include <asm/thread_info.h> |
a0ab3668 PM |
16 | #include <asm/mmu.h> |
17 | #include <cpu/mmu_context.h> | |
1da177e4 | 18 | |
b7e108ee PM |
19 | #ifdef CONFIG_CPU_SH4A |
20 | #define SYNCO() synco | |
21 | ||
22 | #define PREFI(label, reg) \ | |
23 | mov.l label, reg; \ | |
24 | prefi @reg | |
25 | #else | |
26 | #define SYNCO() | |
27 | #define PREFI(label, reg) | |
28 | #endif | |
29 | ||
1da177e4 LT |
30 | .section .empty_zero_page, "aw" |
31 | ENTRY(empty_zero_page) | |
32 | .long 1 /* MOUNT_ROOT_RDONLY */ | |
33 | .long 0 /* RAMDISK_FLAGS */ | |
34 | .long 0x0200 /* ORIG_ROOT_DEV */ | |
35 | .long 1 /* LOADER_TYPE */ | |
972ad0e0 PM |
36 | .long 0x00000000 /* INITRD_START */ |
37 | .long 0x00000000 /* INITRD_SIZE */ | |
a0ab3668 | 38 | #ifdef CONFIG_32BIT |
7a2eacb7 SM |
39 | .long 0x53453f00 + 32 /* "SE?" = 32 bit */ |
40 | #else | |
41 | .long 0x53453f00 + 29 /* "SE?" = 29 bit */ | |
42 | #endif | |
e2dfb912 PM |
43 | 1: |
44 | .skip PAGE_SIZE - empty_zero_page - 1b | |
1da177e4 | 45 | |
bbe215c2 | 46 | __HEAD |
339547bf | 47 | |
1da177e4 LT |
48 | /* |
49 | * Condition at the entry of _stext: | |
50 | * | |
51 | * BSC has already been initialized. | |
52 | * INTC may or may not be initialized. | |
53 | * VBR may or may not be initialized. | |
54 | * MMU may or may not be initialized. | |
55 | * Cache may or may not be initialized. | |
56 | * Hardware (including on-chip modules) may or may not be initialized. | |
57 | * | |
58 | */ | |
59 | ENTRY(_stext) | |
60 | ! Initialize Status Register | |
61 | mov.l 1f, r0 ! MD=1, RB=0, BL=0, IMASK=0xF | |
62 | ldc r0, sr | |
63 | ! Initialize global interrupt mask | |
de398406 | 64 | #ifdef CONFIG_CPU_HAS_SR_RB |
aba1030a | 65 | mov #0, r0 |
1da177e4 | 66 | ldc r0, r6_bank |
de398406 YS |
67 | #endif |
68 | ||
b7e108ee PM |
69 | /* |
70 | * Prefetch if possible to reduce cache miss penalty. | |
71 | * | |
72 | * We do this early on for SH-4A as a micro-optimization, | |
73 | * as later on we will have speculative execution enabled | |
74 | * and this will become less of an issue. | |
75 | */ | |
76 | PREFI(5f, r0) | |
77 | PREFI(6f, r0) | |
78 | ||
1da177e4 LT |
79 | ! |
80 | mov.l 2f, r0 | |
81 | mov r0, r15 ! Set initial r15 (stack pointer) | |
de398406 | 82 | #ifdef CONFIG_CPU_HAS_SR_RB |
aba1030a | 83 | mov.l 7f, r0 |
1da177e4 | 84 | ldc r0, r7_bank ! ... and initial thread_info |
de398406 | 85 | #endif |
740a3e67 PM |
86 | |
87 | #ifndef CONFIG_SH_NO_BSS_INIT | |
88 | /* | |
89 | * Don't clear BSS if running on slow platforms such as an RTL simulation, | |
90 | * remote memory via SHdebug link, etc. For these the memory can be guaranteed | |
91 | * to be all zero on boot anyway. | |
92 | */ | |
93 | ! Clear BSS area | |
aba1030a PM |
94 | #ifdef CONFIG_SMP |
95 | mov.l 3f, r0 | |
96 | cmp/eq #0, r0 ! skip clear if set to zero | |
97 | bt 10f | |
98 | #endif | |
99 | ||
1da177e4 LT |
100 | mov.l 3f, r1 |
101 | add #4, r1 | |
102 | mov.l 4f, r2 | |
103 | mov #0, r0 | |
104 | 9: cmp/hs r2, r1 | |
105 | bf/s 9b ! while (r1 < r2) | |
106 | mov.l r0,@-r2 | |
b7e108ee | 107 | |
aba1030a | 108 | 10: |
740a3e67 PM |
109 | #endif |
110 | ||
b7e108ee PM |
111 | ! Additional CPU initialization |
112 | mov.l 6f, r0 | |
113 | jsr @r0 | |
114 | nop | |
115 | ||
116 | SYNCO() ! Wait for pending instructions.. | |
aba1030a | 117 | |
1da177e4 LT |
118 | ! Start kernel |
119 | mov.l 5f, r0 | |
120 | jmp @r0 | |
121 | nop | |
122 | ||
123 | .balign 4 | |
de398406 YS |
124 | #if defined(CONFIG_CPU_SH2) |
125 | 1: .long 0x000000F0 ! IMASK=0xF | |
126 | #else | |
1da177e4 | 127 | 1: .long 0x400080F0 ! MD=1, RB=0, BL=0, FD=1, IMASK=0xF |
de398406 | 128 | #endif |
aba1030a | 129 | ENTRY(stack_start) |
d153ea88 | 130 | 2: .long init_thread_union+THREAD_SIZE |
1da177e4 LT |
131 | 3: .long __bss_start |
132 | 4: .long _end | |
133 | 5: .long start_kernel | |
134 | 6: .long sh_cpu_init | |
aba1030a | 135 | 7: .long init_thread_union |