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 14 .type __switch_data, %object 15__switch_data: 16 .long __mmap_switched 17 .long __data_loc @ r4 18 .long __data_start @ r5 19 .long __bss_start @ r6 20 .long _end @ r7 21 .long processor_id @ r4 22 .long __machine_arch_type @ r5 23 .long cr_alignment @ r6 24 .long init_thread_union + THREAD_START_SP @ sp 25 26/* 27 * The following fragment of code is executed with the MMU on in MMU mode, 28 * and uses absolute addresses; this is not position independent. 29 * 30 * r0 = cp#15 control register 31 * r1 = machine ID 32 * r9 = processor ID 33 */ 34 .type __mmap_switched, %function 35__mmap_switched: 36 adr r3, __switch_data + 4 37 38 ldmia r3!, {r4, r5, r6, r7} 39 cmp r4, r5 @ Copy data segment if needed 401: cmpne r5, r6 41 ldrne fp, [r4], #4 42 strne fp, [r5], #4 43 bne 1b 44 45 mov fp, #0 @ Clear BSS (and zero fp) 461: cmp r6, r7 47 strcc fp, [r6],#4 48 bcc 1b 49 50 ldmia r3, {r4, r5, r6, sp} 51 str r9, [r4] @ Save processor ID 52 str r1, [r5] @ Save machine type 53 bic r4, r0, #CR_A @ Clear 'A' bit 54 stmia r6, {r0, r4} @ Save control register values 55 b start_kernel 56 57/* 58 * Exception handling. Something went wrong and we can't proceed. We 59 * ought to tell the user, but since we don't have any guarantee that 60 * we're even running on the right architecture, we do virtually nothing. 61 * 62 * If CONFIG_DEBUG_LL is set we try to print out something about the error 63 * and hope for the best (useful if bootloader fails to pass a proper 64 * machine ID for example). 65 */ 66 67 .type __error_p, %function 68__error_p: 69#ifdef CONFIG_DEBUG_LL 70 adr r0, str_p1 71 bl printascii 72 b __error 73str_p1: .asciz "\nError: unrecognized/unsupported processor variant.\n" 74 .align 75#endif 76 77 .type __error_a, %function 78__error_a: 79#ifdef CONFIG_DEBUG_LL 80 mov r4, r1 @ preserve machine ID 81 adr r0, str_a1 82 bl printascii 83 mov r0, r4 84 bl printhex8 85 adr r0, str_a2 86 bl printascii 87 adr r3, 3f 88 ldmia r3, {r4, r5, r6} @ get machine desc list 89 sub r4, r3, r4 @ get offset between virt&phys 90 add r5, r5, r4 @ convert virt addresses to 91 add r6, r6, r4 @ physical address space 921: ldr r0, [r5, #MACHINFO_TYPE] @ get machine type 93 bl printhex8 94 mov r0, #'\t' 95 bl printch 96 ldr r0, [r5, #MACHINFO_NAME] @ get machine name 97 add r0, r0, r4 98 bl printascii 99 mov r0, #'\n' 100 bl printch 101 add r5, r5, #SIZEOF_MACHINE_DESC @ next machine_desc 102 cmp r5, r6 103 blo 1b 104 adr r0, str_a3 105 bl printascii 106 b __error 107str_a1: .asciz "\nError: unrecognized/unsupported machine ID (r1 = 0x" 108str_a2: .asciz ").\n\nAvailable machine support:\n\nID (hex)\tNAME\n" 109str_a3: .asciz "\nPlease check your kernel config and/or bootloader.\n" 110 .align 111#endif 112 113 .type __error, %function 114__error: 115#ifdef CONFIG_ARCH_RPC 116/* 117 * Turn the screen red on a error - RiscPC only. 118 */ 119 mov r0, #0x02000000 120 mov r3, #0x11 121 orr r3, r3, r3, lsl #8 122 orr r3, r3, r3, lsl #16 123 str r3, [r0], #4 124 str r3, [r0], #4 125 str r3, [r0], #4 126 str r3, [r0], #4 127#endif 1281: mov r0, r0 129 b 1b 130 131 132/* 133 * Read processor ID register (CP#15, CR0), and look up in the linker-built 134 * supported processor list. Note that we can't use the absolute addresses 135 * for the __proc_info lists since we aren't running with the MMU on 136 * (and therefore, we are not in the correct address space). We have to 137 * calculate the offset. 138 * 139 * r9 = cpuid 140 * Returns: 141 * r3, r4, r6 corrupted 142 * r5 = proc_info pointer in physical address space 143 * r9 = cpuid (preserved) 144 */ 145 .type __lookup_processor_type, %function 146__lookup_processor_type: 147 adr r3, 3f 148 ldmda r3, {r5 - r7} 149 sub r3, r3, r7 @ get offset between virt&phys 150 add r5, r5, r3 @ convert virt addresses to 151 add r6, r6, r3 @ physical address space 1521: ldmia r5, {r3, r4} @ value, mask 153 and r4, r4, r9 @ mask wanted bits 154 teq r3, r4 155 beq 2f 156 add r5, r5, #PROC_INFO_SZ @ sizeof(proc_info_list) 157 cmp r5, r6 158 blo 1b 159 mov r5, #0 @ unknown processor 1602: mov pc, lr 161 162/* 163 * This provides a C-API version of the above function. 164 */ 165ENTRY(lookup_processor_type) 166 stmfd sp!, {r4 - r7, r9, lr} 167 mov r9, r0 168 bl __lookup_processor_type 169 mov r0, r5 170 ldmfd sp!, {r4 - r7, r9, pc} 171 172/* 173 * Look in include/asm-arm/procinfo.h and arch/arm/kernel/arch.[ch] for 174 * more information about the __proc_info and __arch_info structures. 175 */ 176 .long __proc_info_begin 177 .long __proc_info_end 1783: .long . 179 .long __arch_info_begin 180 .long __arch_info_end 181 182/* 183 * Lookup machine architecture in the linker-build list of architectures. 184 * Note that we can't use the absolute addresses for the __arch_info 185 * lists since we aren't running with the MMU on (and therefore, we are 186 * not in the correct address space). We have to calculate the offset. 187 * 188 * r1 = machine architecture number 189 * Returns: 190 * r3, r4, r6 corrupted 191 * r5 = mach_info pointer in physical address space 192 */ 193 .type __lookup_machine_type, %function 194__lookup_machine_type: 195 adr r3, 3b 196 ldmia r3, {r4, r5, r6} 197 sub r3, r3, r4 @ get offset between virt&phys 198 add r5, r5, r3 @ convert virt addresses to 199 add r6, r6, r3 @ physical address space 2001: ldr r3, [r5, #MACHINFO_TYPE] @ get machine type 201 teq r3, r1 @ matches loader number? 202 beq 2f @ found 203 add r5, r5, #SIZEOF_MACHINE_DESC @ next machine_desc 204 cmp r5, r6 205 blo 1b 206 mov r5, #0 @ unknown machine 2072: mov pc, lr 208 209/* 210 * This provides a C-API version of the above function. 211 */ 212ENTRY(lookup_machine_type) 213 stmfd sp!, {r4 - r6, lr} 214 mov r1, r0 215 bl __lookup_machine_type 216 mov r0, r5 217 ldmfd sp!, {r4 - r6, pc} 218