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).
28 #ifdef CONFIG_DEBUG_LL
29 mov r4, r1 @ preserve machine ID
37 ldmia r3, {r4, r5, r6} @ get machine desc list
38 sub r4, r3, r4 @ get offset between virt&phys
39 add r5, r5, r4 @ convert virt addresses to
40 add r6, r6, r4 @ physical address space
41 1: ldr r0, [r5, #MACHINFO_TYPE] @ get machine type
45 ldr r0, [r5, #MACHINFO_NAME] @ get machine name
50 add r5, r5, #SIZEOF_MACHINE_DESC @ next machine_desc
58 str_a1: .asciz "\nError: unrecognized/unsupported machine ID (r1 = 0x"
59 str_a2: .asciz ").\n\nAvailable machine support:\n\nID (hex)\tNAME\n"
60 str_a3: .asciz "\nPlease check your kernel config and/or bootloader.\n"
65 * Look in <asm/procinfo.h> and arch/arm/kernel/arch.[ch] for
66 * more information about the __proc_info and __arch_info structures.
70 .long __arch_info_begin
74 * Lookup machine architecture in the linker-build list of architectures.
75 * Note that we can't use the absolute addresses for the __arch_info
76 * lists since we aren't running with the MMU on (and therefore, we are
77 * not in the correct address space). We have to calculate the offset.
79 * r1 = machine architecture number
81 * r3, r4, r6 corrupted
82 * r5 = mach_info pointer in physical address space
84 __lookup_machine_type:
86 ldmia r3, {r4, r5, r6}
87 sub r3, r3, r4 @ get offset between virt&phys
88 add r5, r5, r3 @ convert virt addresses to
89 add r6, r6, r3 @ physical address space
90 1: ldr r3, [r5, #MACHINFO_TYPE] @ get machine type
91 teq r3, r1 @ matches loader number?
93 add r5, r5, #SIZEOF_MACHINE_DESC @ next machine_desc
96 mov r5, #0 @ unknown machine
98 ENDPROC(__lookup_machine_type)
100 /* Determine validity of the r2 atags pointer. The heuristic requires
101 * that the pointer be aligned, in the first 16k of physical RAM and
102 * that the ATAG_CORE marker is first and present. Future revisions
103 * of this function may be more lenient with the physical address and
104 * may also be able to move the ATAGS block if necessary.
109 * r2 either valid atags pointer, or zero
113 tst r2, #0x3 @ aligned?
116 ldr r5, [r2, #0] @ is first tag ATAG_CORE?
117 cmp r5, #ATAG_CORE_SIZE
118 cmpne r5, #ATAG_CORE_SIZE_EMPTY
125 mov pc, lr @ atag pointer is ok
132 * The following fragment of code is executed with the MMU on in MMU mode,
133 * and uses absolute addresses; this is not position independent.
135 * r0 = cp#15 control register
142 adr r3, __mmap_switched_data
144 ldmia r3!, {r4, r5, r6, r7}
145 cmp r4, r5 @ Copy data segment if needed
151 mov fp, #0 @ Clear BSS (and zero fp)
156 ARM( ldmia r3, {r4, r5, r6, r7, sp})
157 THUMB( ldmia r3, {r4, r5, r6, r7} )
158 THUMB( ldr sp, [r3, #16] )
159 str r9, [r4] @ Save processor ID
160 str r1, [r5] @ Save machine type
161 str r2, [r6] @ Save atags pointer
162 bic r4, r0, #CR_A @ Clear 'A' bit
163 stmia r7, {r0, r4} @ Save control register values
165 ENDPROC(__mmap_switched)
168 .type __mmap_switched_data, %object
169 __mmap_switched_data:
170 .long __data_loc @ r4
172 .long __bss_start @ r6
174 .long processor_id @ r4
175 .long __machine_arch_type @ r5
176 .long __atags_pointer @ r6
177 .long cr_alignment @ r7
178 .long init_thread_union + THREAD_START_SP @ sp
179 .size __mmap_switched_data, . - __mmap_switched_data
182 * This provides a C-API version of __lookup_machine_type
184 ENTRY(lookup_machine_type)
185 stmfd sp!, {r4 - r6, lr}
187 bl __lookup_machine_type
189 ldmfd sp!, {r4 - r6, pc}
190 ENDPROC(lookup_machine_type)
193 * This provides a C-API version of __lookup_processor_type
195 ENTRY(lookup_processor_type)
196 stmfd sp!, {r4 - r6, r9, lr}
198 bl __lookup_processor_type
200 ldmfd sp!, {r4 - r6, r9, pc}
201 ENDPROC(lookup_processor_type)
204 * Read processor ID register (CP#15, CR0), and look up in the linker-built
205 * supported processor list. Note that we can't use the absolute addresses
206 * for the __proc_info lists since we aren't running with the MMU on
207 * (and therefore, we are not in the correct address space). We have to
208 * calculate the offset.
212 * r3, r4, r6 corrupted
213 * r5 = proc_info pointer in physical address space
214 * r9 = cpuid (preserved)
217 __lookup_processor_type:
218 adr r3, __lookup_processor_type_data
220 sub r3, r3, r4 @ get offset between virt&phys
221 add r5, r5, r3 @ convert virt addresses to
222 add r6, r6, r3 @ physical address space
223 1: ldmia r5, {r3, r4} @ value, mask
224 and r4, r4, r9 @ mask wanted bits
227 add r5, r5, #PROC_INFO_SZ @ sizeof(proc_info_list)
230 mov r5, #0 @ unknown processor
232 ENDPROC(__lookup_processor_type)
235 * Look in <asm/procinfo.h> for information about the __proc_info structure.
238 .type __lookup_processor_type_data, %object
239 __lookup_processor_type_data:
241 .long __proc_info_begin
242 .long __proc_info_end
243 .size __lookup_processor_type_data, . - __lookup_processor_type_data
246 #ifdef CONFIG_DEBUG_LL
254 str_p1: .asciz "\nError: unrecognized/unsupported processor variant (0x"
255 str_p2: .asciz ").\n"
261 #ifdef CONFIG_ARCH_RPC
263 * Turn the screen red on a error - RiscPC only.
267 orr r3, r3, r3, lsl #8
268 orr r3, r3, r3, lsl #16