aboutsummaryrefslogtreecommitdiff
path: root/arch/arm/kernel/head-common.S
blob: 6e0375e7db055bc82cf0674b37b74646e2d64ff0 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
/*
 *  linux/arch/arm/kernel/head-common.S
 *
 *  Copyright (C) 1994-2002 Russell King
 *  Copyright (c) 2003 ARM Limited
 *  All Rights Reserved
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 */
#include <asm/assembler.h>

#define ATAG_CORE 0x54410001
#define ATAG_CORE_SIZE ((2*4 + 3*4) >> 2)
#define ATAG_CORE_SIZE_EMPTY ((2*4) >> 2)

#ifdef CONFIG_CPU_BIG_ENDIAN
#define OF_DT_MAGIC 0xd00dfeed
#else
#define OF_DT_MAGIC 0xedfe0dd0 /* 0xd00dfeed in big-endian */
#endif

/*
 * Exception handling.  Something went wrong and we can't proceed.  We
 * ought to tell the user, but since we don't have any guarantee that
 * we're even running on the right architecture, we do virtually nothing.
 *
 * If CONFIG_DEBUG_LL is set we try to print out something about the error
 * and hope for the best (useful if bootloader fails to pass a proper
 * machine ID for example).
 */
	__HEAD

/* Determine validity of the r2 atags pointer.  The heuristic requires
 * that the pointer be aligned, in the first 16k of physical RAM and
 * that the ATAG_CORE marker is first and present.  If CONFIG_OF_FLATTREE
 * is selected, then it will also accept a dtb pointer.  Future revisions
 * of this function may be more lenient with the physical address and
 * may also be able to move the ATAGS block if necessary.
 *
 * Returns:
 *  r2 either valid atags pointer, valid dtb pointer, or zero
 *  r5, r6 corrupted
 */
__vet_atags:
	tst	r2, #0x3			@ aligned?
	bne	1f

	ldr	r5, [r2, #0]
#ifdef CONFIG_OF_FLATTREE
	ldr	r6, =OF_DT_MAGIC		@ is it a DTB?
	cmp	r5, r6
	beq	2f
#endif
	cmp	r5, #ATAG_CORE_SIZE		@ is first tag ATAG_CORE?
	cmpne	r5, #ATAG_CORE_SIZE_EMPTY
	bne	1f
	ldr	r5, [r2, #4]
	ldr	r6, =ATAG_CORE
	cmp	r5, r6
	bne	1f

2:	ret	lr				@ atag/dtb pointer is ok

1:	mov	r2, #0
	ret	lr
ENDPROC(__vet_atags)

/*
 * The following fragment of code is executed with the MMU on in MMU mode,
 * and uses absolute addresses; this is not position independent.
 *
 *  r0  = cp#15 control register
 *  r1  = machine ID
 *  r2  = atags/dtb pointer
 *  r9  = processor ID
 */
	__INIT
__mmap_switched:

	mov	r7, r1
	mov	r8, r2
	mov	r10, r0

	adr	r4, __mmap_switched_data
	mov	fp, #0

#if defined(CONFIG_XIP_DEFLATED_DATA)
   ARM(	ldr	sp, [r4], #4 )
 THUMB(	ldr	sp, [r4] )
 THUMB(	add	r4, #4 )
	bl	__inflate_kernel_data		@ decompress .data to RAM
	teq	r0, #0
	bne	__error
#elif defined(CONFIG_XIP_KERNEL)
   ARM(	ldmia	r4!, {r0, r1, r2, sp} )
 THUMB(	ldmia	r4!, {r0, r1, r2, r3} )
 THUMB(	mov	sp, r3 )
	sub	r2, r2, r1
	bl	memcpy				@ copy .data to RAM
#endif

   ARM(	ldmia	r4!, {r0, r1, sp} )
 THUMB(	ldmia	r4!, {r0, r1, r3} )
 THUMB(	mov	sp, r3 )
	sub	r2, r1, r0
	mov	r1, #0
	bl	memset				@ clear .bss

	ldmia	r4, {r0, r1, r2, r3}
	str	r9, [r0]			@ Save processor ID
	str	r7, [r1]			@ Save machine type
	str	r8, [r2]			@ Save atags pointer
	cmp	r3, #0
	strne	r10, [r3]			@ Save control register values
	mov	lr, #0
	b	start_kernel
ENDPROC(__mmap_switched)

	.align	2
	.type	__mmap_switched_data, %object
__mmap_switched_data:
#ifdef CONFIG_XIP_KERNEL
#ifndef CONFIG_XIP_DEFLATED_DATA
	.long	_sdata				@ r0
	.long	__data_loc			@ r1
	.long	_edata_loc			@ r2
#endif
	.long	__bss_stop			@ sp (temporary stack in .bss)
#endif

	.long	__bss_start			@ r0
	.long	__bss_stop			@ r1
	.long	init_thread_union + THREAD_START_SP @ sp

	.long	processor_id			@ r0
	.long	__machine_arch_type		@ r1
	.long	__atags_pointer			@ r2
#ifdef CONFIG_CPU_CP15
	.long	cr_alignment			@ r3
#else
	.long	0				@ r3
#endif
	.size	__mmap_switched_data, . - __mmap_switched_data

/*
 * This provides a C-API version of __lookup_processor_type
 */
ENTRY(lookup_processor_type)
	stmfd	sp!, {r4 - r6, r9, lr}
	mov	r9, r0
	bl	__lookup_processor_type
	mov	r0, r5
	ldmfd	sp!, {r4 - r6, r9, pc}
ENDPROC(lookup_processor_type)

	__FINIT
	.text

/*
 * Read processor ID register (CP#15, CR0), and look up in the linker-built
 * supported processor list.  Note that we can't use the absolute addresses
 * for the __proc_info lists since we aren't running with the MMU on
 * (and therefore, we are not in the correct address space).  We have to
 * calculate the offset.
 *
 *	r9 = cpuid
 * Returns:
 *	r3, r4, r6 corrupted
 *	r5 = proc_info pointer in physical address space
 *	r9 = cpuid (preserved)
 */
__lookup_processor_type:
	adr	r3, __lookup_processor_type_data
	ldmia	r3, {r4 - r6}
	sub	r3, r3, r4			@ get offset between virt&phys
	add	r5, r5, r3			@ convert virt addresses to
	add	r6, r6, r3			@ physical address space
1:	ldmia	r5, {r3, r4}			@ value, mask
	and	r4, r4, r9			@ mask wanted bits
	teq	r3, r4
	beq	2f
	add	r5, r5, #PROC_INFO_SZ		@ sizeof(proc_info_list)
	cmp	r5, r6
	blo	1b
	mov	r5, #0				@ unknown processor
2:	ret	lr
ENDPROC(__lookup_processor_type)

/*
 * Look in <asm/procinfo.h> for information about the __proc_info structure.
 */
	.align	2
	.type	__lookup_processor_type_data, %object
__lookup_processor_type_data:
	.long	.
	.long	__proc_info_begin
	.long	__proc_info_end
	.size	__lookup_processor_type_data, . - __lookup_processor_type_data

__error_lpae:
#ifdef CONFIG_DEBUG_LL
	adr	r0, str_lpae
	bl 	printascii
	b	__error
str_lpae: .asciz "\nError: Kernel with LPAE support, but CPU does not support LPAE.\n"
#else
	b	__error
#endif
	.align
ENDPROC(__error_lpae)

__error_p:
#ifdef CONFIG_DEBUG_LL
	adr	r0, str_p1
	bl	printascii
	mov	r0, r9
	bl	printhex8
	adr	r0, str_p2
	bl	printascii
	b	__error
str_p1:	.asciz	"\nError: unrecognized/unsupported processor variant (0x"
str_p2:	.asciz	").\n"
	.align
#endif
ENDPROC(__error_p)

__error:
#ifdef CONFIG_ARCH_RPC
/*
 * Turn the screen red on a error - RiscPC only.
 */
	mov	r0, #0x02000000
	mov	r3, #0x11
	orr	r3, r3, r3, lsl #8
	orr	r3, r3, r3, lsl #16
	str	r3, [r0], #4
	str	r3, [r0], #4
	str	r3, [r0], #4
	str	r3, [r0], #4
#endif
1:	mov	r0, r0
	b	1b
ENDPROC(__error)