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75d90832 HC |
1 | /* |
2 | * linux/arch/arm/kernel/head-common.S | |
3 | * | |
4 | * Copyright (C) 1994-2002 Russell King | |
5 | * Copyright (c) 2003 ARM Limited | |
6 | * All Rights Reserved | |
7 | * | |
8 | * This program is free software; you can redistribute it and/or modify | |
9 | * it under the terms of the GNU General Public License version 2 as | |
10 | * published by the Free Software Foundation. | |
11 | * | |
12 | */ | |
13 | ||
9c4c9f38 GU |
14 | #define ATAG_CORE 0x54410001 |
15 | #define ATAG_CORE_SIZE ((2*4 + 3*4) >> 2) | |
31abdb74 | 16 | #define ATAG_CORE_SIZE_EMPTY ((2*4) >> 2) |
9c4c9f38 | 17 | |
88987ef9 | 18 | .align 2 |
75d90832 HC |
19 | .type __switch_data, %object |
20 | __switch_data: | |
21 | .long __mmap_switched | |
22 | .long __data_loc @ r4 | |
842eab40 | 23 | .long _sdata @ r5 |
75d90832 HC |
24 | .long __bss_start @ r6 |
25 | .long _end @ r7 | |
26 | .long processor_id @ r4 | |
27 | .long __machine_arch_type @ r5 | |
9d20fdd5 BG |
28 | .long __atags_pointer @ r6 |
29 | .long cr_alignment @ r7 | |
75d90832 HC |
30 | .long init_thread_union + THREAD_START_SP @ sp |
31 | ||
32 | /* | |
33 | * The following fragment of code is executed with the MMU on in MMU mode, | |
34 | * and uses absolute addresses; this is not position independent. | |
35 | * | |
36 | * r0 = cp#15 control register | |
37 | * r1 = machine ID | |
9d20fdd5 | 38 | * r2 = atags pointer |
75d90832 HC |
39 | * r9 = processor ID |
40 | */ | |
75d90832 HC |
41 | __mmap_switched: |
42 | adr r3, __switch_data + 4 | |
43 | ||
44 | ldmia r3!, {r4, r5, r6, r7} | |
45 | cmp r4, r5 @ Copy data segment if needed | |
46 | 1: cmpne r5, r6 | |
47 | ldrne fp, [r4], #4 | |
48 | strne fp, [r5], #4 | |
49 | bne 1b | |
50 | ||
51 | mov fp, #0 @ Clear BSS (and zero fp) | |
52 | 1: cmp r6, r7 | |
53 | strcc fp, [r6],#4 | |
54 | bcc 1b | |
55 | ||
b86040a5 CM |
56 | ARM( ldmia r3, {r4, r5, r6, r7, sp}) |
57 | THUMB( ldmia r3, {r4, r5, r6, r7} ) | |
58 | THUMB( ldr sp, [r3, #16] ) | |
75d90832 HC |
59 | str r9, [r4] @ Save processor ID |
60 | str r1, [r5] @ Save machine type | |
9d20fdd5 | 61 | str r2, [r6] @ Save atags pointer |
75d90832 | 62 | bic r4, r0, #CR_A @ Clear 'A' bit |
9d20fdd5 | 63 | stmia r7, {r0, r4} @ Save control register values |
75d90832 | 64 | b start_kernel |
93ed3970 | 65 | ENDPROC(__mmap_switched) |
75d90832 HC |
66 | |
67 | /* | |
68 | * Exception handling. Something went wrong and we can't proceed. We | |
69 | * ought to tell the user, but since we don't have any guarantee that | |
70 | * we're even running on the right architecture, we do virtually nothing. | |
71 | * | |
72 | * If CONFIG_DEBUG_LL is set we try to print out something about the error | |
73 | * and hope for the best (useful if bootloader fails to pass a proper | |
74 | * machine ID for example). | |
75 | */ | |
75d90832 HC |
76 | __error_p: |
77 | #ifdef CONFIG_DEBUG_LL | |
78 | adr r0, str_p1 | |
79 | bl printascii | |
84081bd2 LB |
80 | mov r0, r9 |
81 | bl printhex8 | |
82 | adr r0, str_p2 | |
83 | bl printascii | |
75d90832 | 84 | b __error |
84081bd2 LB |
85 | str_p1: .asciz "\nError: unrecognized/unsupported processor variant (0x" |
86 | str_p2: .asciz ").\n" | |
75d90832 HC |
87 | .align |
88 | #endif | |
93ed3970 | 89 | ENDPROC(__error_p) |
75d90832 | 90 | |
75d90832 HC |
91 | __error_a: |
92 | #ifdef CONFIG_DEBUG_LL | |
93 | mov r4, r1 @ preserve machine ID | |
94 | adr r0, str_a1 | |
95 | bl printascii | |
96 | mov r0, r4 | |
97 | bl printhex8 | |
98 | adr r0, str_a2 | |
99 | bl printascii | |
158bc5af | 100 | adr r3, 4f |
75d90832 HC |
101 | ldmia r3, {r4, r5, r6} @ get machine desc list |
102 | sub r4, r3, r4 @ get offset between virt&phys | |
103 | add r5, r5, r4 @ convert virt addresses to | |
104 | add r6, r6, r4 @ physical address space | |
105 | 1: ldr r0, [r5, #MACHINFO_TYPE] @ get machine type | |
106 | bl printhex8 | |
107 | mov r0, #'\t' | |
108 | bl printch | |
109 | ldr r0, [r5, #MACHINFO_NAME] @ get machine name | |
110 | add r0, r0, r4 | |
111 | bl printascii | |
112 | mov r0, #'\n' | |
113 | bl printch | |
114 | add r5, r5, #SIZEOF_MACHINE_DESC @ next machine_desc | |
115 | cmp r5, r6 | |
116 | blo 1b | |
117 | adr r0, str_a3 | |
118 | bl printascii | |
119 | b __error | |
93ed3970 CM |
120 | ENDPROC(__error_a) |
121 | ||
75d90832 HC |
122 | str_a1: .asciz "\nError: unrecognized/unsupported machine ID (r1 = 0x" |
123 | str_a2: .asciz ").\n\nAvailable machine support:\n\nID (hex)\tNAME\n" | |
124 | str_a3: .asciz "\nPlease check your kernel config and/or bootloader.\n" | |
125 | .align | |
126 | #endif | |
127 | ||
75d90832 HC |
128 | __error: |
129 | #ifdef CONFIG_ARCH_RPC | |
130 | /* | |
131 | * Turn the screen red on a error - RiscPC only. | |
132 | */ | |
133 | mov r0, #0x02000000 | |
134 | mov r3, #0x11 | |
135 | orr r3, r3, r3, lsl #8 | |
136 | orr r3, r3, r3, lsl #16 | |
137 | str r3, [r0], #4 | |
138 | str r3, [r0], #4 | |
139 | str r3, [r0], #4 | |
140 | str r3, [r0], #4 | |
141 | #endif | |
142 | 1: mov r0, r0 | |
143 | b 1b | |
93ed3970 | 144 | ENDPROC(__error) |
75d90832 HC |
145 | |
146 | ||
147 | /* | |
148 | * Read processor ID register (CP#15, CR0), and look up in the linker-built | |
149 | * supported processor list. Note that we can't use the absolute addresses | |
150 | * for the __proc_info lists since we aren't running with the MMU on | |
151 | * (and therefore, we are not in the correct address space). We have to | |
152 | * calculate the offset. | |
153 | * | |
154 | * r9 = cpuid | |
155 | * Returns: | |
156 | * r3, r4, r6 corrupted | |
157 | * r5 = proc_info pointer in physical address space | |
158 | * r9 = cpuid (preserved) | |
159 | */ | |
75d90832 HC |
160 | __lookup_processor_type: |
161 | adr r3, 3f | |
b86040a5 CM |
162 | ldmia r3, {r5 - r7} |
163 | add r3, r3, #8 | |
75d90832 HC |
164 | sub r3, r3, r7 @ get offset between virt&phys |
165 | add r5, r5, r3 @ convert virt addresses to | |
166 | add r6, r6, r3 @ physical address space | |
167 | 1: ldmia r5, {r3, r4} @ value, mask | |
168 | and r4, r4, r9 @ mask wanted bits | |
169 | teq r3, r4 | |
170 | beq 2f | |
171 | add r5, r5, #PROC_INFO_SZ @ sizeof(proc_info_list) | |
172 | cmp r5, r6 | |
173 | blo 1b | |
174 | mov r5, #0 @ unknown processor | |
175 | 2: mov pc, lr | |
93ed3970 | 176 | ENDPROC(__lookup_processor_type) |
75d90832 HC |
177 | |
178 | /* | |
179 | * This provides a C-API version of the above function. | |
180 | */ | |
181 | ENTRY(lookup_processor_type) | |
182 | stmfd sp!, {r4 - r7, r9, lr} | |
183 | mov r9, r0 | |
184 | bl __lookup_processor_type | |
185 | mov r0, r5 | |
186 | ldmfd sp!, {r4 - r7, r9, pc} | |
93ed3970 | 187 | ENDPROC(lookup_processor_type) |
75d90832 HC |
188 | |
189 | /* | |
4baa9922 | 190 | * Look in <asm/procinfo.h> and arch/arm/kernel/arch.[ch] for |
75d90832 HC |
191 | * more information about the __proc_info and __arch_info structures. |
192 | */ | |
88987ef9 | 193 | .align 2 |
b86040a5 | 194 | 3: .long __proc_info_begin |
75d90832 | 195 | .long __proc_info_end |
b86040a5 | 196 | 4: .long . |
75d90832 HC |
197 | .long __arch_info_begin |
198 | .long __arch_info_end | |
199 | ||
200 | /* | |
201 | * Lookup machine architecture in the linker-build list of architectures. | |
202 | * Note that we can't use the absolute addresses for the __arch_info | |
203 | * lists since we aren't running with the MMU on (and therefore, we are | |
204 | * not in the correct address space). We have to calculate the offset. | |
205 | * | |
206 | * r1 = machine architecture number | |
207 | * Returns: | |
208 | * r3, r4, r6 corrupted | |
209 | * r5 = mach_info pointer in physical address space | |
210 | */ | |
75d90832 | 211 | __lookup_machine_type: |
b86040a5 | 212 | adr r3, 4b |
75d90832 HC |
213 | ldmia r3, {r4, r5, r6} |
214 | sub r3, r3, r4 @ get offset between virt&phys | |
215 | add r5, r5, r3 @ convert virt addresses to | |
216 | add r6, r6, r3 @ physical address space | |
217 | 1: ldr r3, [r5, #MACHINFO_TYPE] @ get machine type | |
218 | teq r3, r1 @ matches loader number? | |
219 | beq 2f @ found | |
220 | add r5, r5, #SIZEOF_MACHINE_DESC @ next machine_desc | |
221 | cmp r5, r6 | |
222 | blo 1b | |
223 | mov r5, #0 @ unknown machine | |
224 | 2: mov pc, lr | |
93ed3970 | 225 | ENDPROC(__lookup_machine_type) |
75d90832 HC |
226 | |
227 | /* | |
228 | * This provides a C-API version of the above function. | |
229 | */ | |
230 | ENTRY(lookup_machine_type) | |
231 | stmfd sp!, {r4 - r6, lr} | |
232 | mov r1, r0 | |
233 | bl __lookup_machine_type | |
234 | mov r0, r5 | |
235 | ldmfd sp!, {r4 - r6, pc} | |
93ed3970 | 236 | ENDPROC(lookup_machine_type) |
9d20fdd5 BG |
237 | |
238 | /* Determine validity of the r2 atags pointer. The heuristic requires | |
239 | * that the pointer be aligned, in the first 16k of physical RAM and | |
240 | * that the ATAG_CORE marker is first and present. Future revisions | |
241 | * of this function may be more lenient with the physical address and | |
242 | * may also be able to move the ATAGS block if necessary. | |
243 | * | |
244 | * r8 = machinfo | |
245 | * | |
246 | * Returns: | |
247 | * r2 either valid atags pointer, or zero | |
248 | * r5, r6 corrupted | |
249 | */ | |
9d20fdd5 BG |
250 | __vet_atags: |
251 | tst r2, #0x3 @ aligned? | |
252 | bne 1f | |
253 | ||
254 | ldr r5, [r2, #0] @ is first tag ATAG_CORE? | |
31abdb74 DB |
255 | cmp r5, #ATAG_CORE_SIZE |
256 | cmpne r5, #ATAG_CORE_SIZE_EMPTY | |
9d20fdd5 BG |
257 | bne 1f |
258 | ldr r5, [r2, #4] | |
259 | ldr r6, =ATAG_CORE | |
260 | cmp r5, r6 | |
261 | bne 1f | |
262 | ||
263 | mov pc, lr @ atag pointer is ok | |
264 | ||
265 | 1: mov r2, #0 | |
266 | mov pc, lr | |
93ed3970 | 267 | ENDPROC(__vet_atags) |