2 * linux/arch/arm/kernel/head-common.S
4 * Copyright (C) 1994-2002 Russell King
5 * Copyright (c) 2003 ARM Limited
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.
14 #define ATAG_CORE 0x54410001
15 #define ATAG_CORE_SIZE ((2*4 + 3*4) >> 2)
16 #define ATAG_CORE_SIZE_EMPTY ((2*4) >> 2)
19 * Exception handling. Something went wrong and we can't proceed. We
20 * ought to tell the user, but since we don't have any guarantee that
21 * we're even running on the right architecture, we do virtually nothing.
23 * If CONFIG_DEBUG_LL is set we try to print out something about the error
24 * and hope for the best (useful if bootloader fails to pass a proper
25 * machine ID for example).
29 #ifdef CONFIG_DEBUG_LL
30 mov r4, r1 @ preserve machine ID
37 adr r3, __lookup_machine_type_data
38 ldmia r3, {r4, r5, r6} @ get machine desc list
39 sub r4, r3, r4 @ get offset between virt&phys
40 add r5, r5, r4 @ convert virt addresses to
41 add r6, r6, r4 @ physical address space
42 1: ldr r0, [r5, #MACHINFO_TYPE] @ get machine type
46 ldr r0, [r5, #MACHINFO_NAME] @ get machine name
51 add r5, r5, #SIZEOF_MACHINE_DESC @ next machine_desc
59 str_a1: .asciz "\nError: unrecognized/unsupported machine ID (r1 = 0x"
60 str_a2: .asciz ").\n\nAvailable machine support:\n\nID (hex)\tNAME\n"
61 str_a3: .asciz "\nPlease check your kernel config and/or bootloader.\n"
68 * Lookup machine architecture in the linker-build list of architectures.
69 * Note that we can't use the absolute addresses for the __arch_info
70 * lists since we aren't running with the MMU on (and therefore, we are
71 * not in the correct address space). We have to calculate the offset.
73 * r1 = machine architecture number
75 * r3, r4, r6 corrupted
76 * r5 = mach_info pointer in physical address space
78 __lookup_machine_type:
79 adr r3, __lookup_machine_type_data
80 ldmia r3, {r4, r5, r6}
81 sub r3, r3, r4 @ get offset between virt&phys
82 add r5, r5, r3 @ convert virt addresses to
83 add r6, r6, r3 @ physical address space
84 1: ldr r3, [r5, #MACHINFO_TYPE] @ get machine type
85 teq r3, r1 @ matches loader number?
87 add r5, r5, #SIZEOF_MACHINE_DESC @ next machine_desc
90 mov r5, #0 @ unknown machine
92 ENDPROC(__lookup_machine_type)
95 * Look in arch/arm/kernel/arch.[ch] for information about the
96 * __arch_info structures.
99 .type __lookup_machine_type_data, %object
100 __lookup_machine_type_data:
102 .long __arch_info_begin
103 .long __arch_info_end
104 .size __lookup_machine_type_data, . - __lookup_machine_type_data
106 /* Determine validity of the r2 atags pointer. The heuristic requires
107 * that the pointer be aligned, in the first 16k of physical RAM and
108 * that the ATAG_CORE marker is first and present. Future revisions
109 * of this function may be more lenient with the physical address and
110 * may also be able to move the ATAGS block if necessary.
115 * r2 either valid atags pointer, or zero
119 tst r2, #0x3 @ aligned?
122 ldr r5, [r2, #0] @ is first tag ATAG_CORE?
123 cmp r5, #ATAG_CORE_SIZE
124 cmpne r5, #ATAG_CORE_SIZE_EMPTY
131 mov pc, lr @ atag pointer is ok
138 * The following fragment of code is executed with the MMU on in MMU mode,
139 * and uses absolute addresses; this is not position independent.
141 * r0 = cp#15 control register
148 adr r3, __mmap_switched_data
150 ldmia r3!, {r4, r5, r6, r7}
151 cmp r4, r5 @ Copy data segment if needed
157 mov fp, #0 @ Clear BSS (and zero fp)
162 ARM( ldmia r3, {r4, r5, r6, r7, sp})
163 THUMB( ldmia r3, {r4, r5, r6, r7} )
164 THUMB( ldr sp, [r3, #16] )
165 str r9, [r4] @ Save processor ID
166 str r1, [r5] @ Save machine type
167 str r2, [r6] @ Save atags pointer
168 bic r4, r0, #CR_A @ Clear 'A' bit
169 stmia r7, {r0, r4} @ Save control register values
171 ENDPROC(__mmap_switched)
174 .type __mmap_switched_data, %object
175 __mmap_switched_data:
176 .long __data_loc @ r4
178 .long __bss_start @ r6
180 .long processor_id @ r4
181 .long __machine_arch_type @ r5
182 .long __atags_pointer @ r6
183 .long cr_alignment @ r7
184 .long init_thread_union + THREAD_START_SP @ sp
185 .size __mmap_switched_data, . - __mmap_switched_data
188 * This provides a C-API version of __lookup_machine_type
190 ENTRY(lookup_machine_type)
191 stmfd sp!, {r4 - r6, lr}
193 bl __lookup_machine_type
195 ldmfd sp!, {r4 - r6, pc}
196 ENDPROC(lookup_machine_type)
199 * This provides a C-API version of __lookup_processor_type
201 ENTRY(lookup_processor_type)
202 stmfd sp!, {r4 - r6, r9, lr}
204 bl __lookup_processor_type
206 ldmfd sp!, {r4 - r6, r9, pc}
207 ENDPROC(lookup_processor_type)
210 * Read processor ID register (CP#15, CR0), and look up in the linker-built
211 * supported processor list. Note that we can't use the absolute addresses
212 * for the __proc_info lists since we aren't running with the MMU on
213 * (and therefore, we are not in the correct address space). We have to
214 * calculate the offset.
218 * r3, r4, r6 corrupted
219 * r5 = proc_info pointer in physical address space
220 * r9 = cpuid (preserved)
223 __lookup_processor_type:
224 adr r3, __lookup_processor_type_data
226 sub r3, r3, r4 @ get offset between virt&phys
227 add r5, r5, r3 @ convert virt addresses to
228 add r6, r6, r3 @ physical address space
229 1: ldmia r5, {r3, r4} @ value, mask
230 and r4, r4, r9 @ mask wanted bits
233 add r5, r5, #PROC_INFO_SZ @ sizeof(proc_info_list)
236 mov r5, #0 @ unknown processor
238 ENDPROC(__lookup_processor_type)
241 * Look in <asm/procinfo.h> for information about the __proc_info structure.
244 .type __lookup_processor_type_data, %object
245 __lookup_processor_type_data:
247 .long __proc_info_begin
248 .long __proc_info_end
249 .size __lookup_processor_type_data, . - __lookup_processor_type_data
252 #ifdef CONFIG_DEBUG_LL
260 str_p1: .asciz "\nError: unrecognized/unsupported processor variant (0x"
261 str_p2: .asciz ").\n"
267 #ifdef CONFIG_ARCH_RPC
269 * Turn the screen red on a error - RiscPC only.
273 orr r3, r3, r3, lsl #8
274 orr r3, r3, r3, lsl #16