/* * 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) .align 2 .type __switch_data, %object __switch_data: .long __mmap_switched .long __data_loc @ r4 .long _data @ 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 /* * 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 pointer * r9 = processor ID */ __mmap_switched: adr r3, __switch_data + 4 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) /* * 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). */ __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_a: #ifdef CONFIG_DEBUG_LL mov r4, r1 @ preserve machine ID adr r0, str_a1 bl printascii mov r0, r4 bl printhex8 adr r0, str_a2 bl printascii adr r3, 4f ldmia r3, {r4, r5, r6} @ get machine desc list sub r4, r3, r4 @ get offset between virt&phys add r5, r5, r4 @ convert virt addresses to add r6, r6, r4 @ physical address space 1: ldr r0, [r5, #MACHINFO_TYPE] @ get machine type bl printhex8 mov r0, #'\t' bl printch ldr r0, [r5, #MACHINFO_NAME] @ get machine name add r0, r0, r4 bl printascii mov r0, #'\n' bl printch add r5, r5, #SIZEOF_MACHINE_DESC @ next machine_desc cmp r5, r6 blo 1b adr r0, str_a3 bl printascii b __error ENDPROC(__error_a) str_a1: .asciz "\nError: unrecognized/unsupported machine ID (r1 = 0x" str_a2: .asciz ").\n\nAvailable machine support:\n\nID (hex)\tNAME\n" str_a3: .asciz "\nPlease check your kernel config and/or bootloader.\n" .align #endif __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) /* * 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, 3f ldmia r3, {r5 - r7} add r3, r3, #8 sub r3, r3, r7 @ 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) /* * This provides a C-API version of the above function. */ ENTRY(lookup_processor_type) stmfd sp!, {r4 - r7, r9, lr} mov r9, r0 bl __lookup_processor_type mov r0, r5 ldmfd sp!, {r4 - r7, r9, pc} ENDPROC(lookup_processor_type) /* * Look in <asm/procinfo.h> and arch/arm/kernel/arch.[ch] for * more information about the __proc_info and __arch_info structures. */ .align 2 3: .long __proc_info_begin .long __proc_info_end 4: .long . .long __arch_info_begin .long __arch_info_end /* * Lookup machine architecture in the linker-build list of architectures. * Note that we can't use the absolute addresses for the __arch_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. * * r1 = machine architecture number * Returns: * r3, r4, r6 corrupted * r5 = mach_info pointer in physical address space */ __lookup_machine_type: adr r3, 4b ldmia r3, {r4, r5, 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: ldr r3, [r5, #MACHINFO_TYPE] @ get machine type teq r3, r1 @ matches loader number? beq 2f @ found add r5, r5, #SIZEOF_MACHINE_DESC @ next machine_desc cmp r5, r6 blo 1b mov r5, #0 @ unknown machine 2: mov pc, lr ENDPROC(__lookup_machine_type) /* * This provides a C-API version of the above function. */ ENTRY(lookup_machine_type) stmfd sp!, {r4 - r6, lr} mov r1, r0 bl __lookup_machine_type mov r0, r5 ldmfd sp!, {r4 - r6, pc} ENDPROC(lookup_machine_type) /* 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. 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. * * r8 = machinfo * * Returns: * r2 either valid atags pointer, or zero * r5, r6 corrupted */ __vet_atags: tst r2, #0x3 @ aligned? bne 1f ldr r5, [r2, #0] @ is first tag ATAG_CORE? cmp r5, #ATAG_CORE_SIZE cmpne r5, #ATAG_CORE_SIZE_EMPTY bne 1f ldr r5, [r2, #4] ldr r6, =ATAG_CORE cmp r5, r6 bne 1f mov pc, lr @ atag pointer is ok 1: mov r2, #0 mov pc, lr ENDPROC(__vet_atags)