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Diffstat (limited to 'arch/arm/kernel/head-common.S')
| -rw-r--r-- | arch/arm/kernel/head-common.S | 204 |
1 files changed, 204 insertions, 0 deletions
diff --git a/arch/arm/kernel/head-common.S b/arch/arm/kernel/head-common.S new file mode 100644 index 00000000..854bd223 --- /dev/null +++ b/arch/arm/kernel/head-common.S @@ -0,0 +1,204 @@ +/* + * 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. + * + */ + +#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: mov pc, lr @ atag/dtb pointer is ok + +1: mov r2, #0 + mov pc, 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: + adr r3, __mmap_switched_data + + ldmia r3!, {r4, r5, r6, r7} + cmp r4, r5 @ Copy data segment if needed +1: cmpne r5, r6 + ldrne fp, [r4], #4 + strne fp, [r5], #4 + bne 1b + + mov fp, #0 @ Clear BSS (and zero fp) +1: cmp r6, r7 + strcc fp, [r6],#4 + bcc 1b + + ARM( ldmia r3, {r4, r5, r6, r7, sp}) + THUMB( ldmia r3, {r4, r5, r6, r7} ) + THUMB( ldr sp, [r3, #16] ) + str r9, [r4] @ Save processor ID + str r1, [r5] @ Save machine type + str r2, [r6] @ Save atags pointer + bic r4, r0, #CR_A @ Clear 'A' bit + stmia r7, {r0, r4} @ Save control register values + b start_kernel +ENDPROC(__mmap_switched) + + .align 2 + .type __mmap_switched_data, %object +__mmap_switched_data: + .long __data_loc @ r4 + .long _sdata @ r5 + .long __bss_start @ r6 + .long _end @ r7 + .long processor_id @ r4 + .long __machine_arch_type @ r5 + .long __atags_pointer @ r6 + .long cr_alignment @ r7 + .long init_thread_union + THREAD_START_SP @ sp + .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) + +/* + * 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) + */ + __CPUINIT +__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: mov pc, 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_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) |