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#define ATAG_CORE 0x54410001 15#define ATAG_CORE_SIZE ((2*4 + 3*4) >> 2) 16#define ATAG_CORE_SIZE_EMPTY ((2*4) >> 2) 17 18/* 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. 22 * 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). 26 */ 27 __HEAD 28__error_a: 29#ifdef CONFIG_DEBUG_LL 30 mov r4, r1 @ preserve machine ID 31 adr r0, str_a1 32 bl printascii 33 mov r0, r4 34 bl printhex8 35 adr r0, str_a2 36 bl printascii 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 421: ldr r0, [r5, #MACHINFO_TYPE] @ get machine type 43 bl printhex8 44 mov r0, #'\t' 45 bl printch 46 ldr r0, [r5, #MACHINFO_NAME] @ get machine name 47 add r0, r0, r4 48 bl printascii 49 mov r0, #'\n' 50 bl printch 51 add r5, r5, #SIZEOF_MACHINE_DESC @ next machine_desc 52 cmp r5, r6 53 blo 1b 54 adr r0, str_a3 55 bl printascii 56 b __error 57ENDPROC(__error_a) 58 59str_a1: .asciz "\nError: unrecognized/unsupported machine ID (r1 = 0x" 60str_a2: .asciz ").\n\nAvailable machine support:\n\nID (hex)\tNAME\n" 61str_a3: .asciz "\nPlease check your kernel config and/or bootloader.\n" 62 .align 63#endif 64 65/* 66 * Lookup machine architecture in the linker-build list of architectures. 67 * Note that we can't use the absolute addresses for the __arch_info 68 * lists since we aren't running with the MMU on (and therefore, we are 69 * not in the correct address space). We have to calculate the offset. 70 * 71 * r1 = machine architecture number 72 * Returns: 73 * r3, r4, r6 corrupted 74 * r5 = mach_info pointer in physical address space 75 */ 76__lookup_machine_type: 77 adr r3, __lookup_machine_type_data 78 ldmia r3, {r4, r5, r6} 79 sub r3, r3, r4 @ get offset between virt&phys 80 add r5, r5, r3 @ convert virt addresses to 81 add r6, r6, r3 @ physical address space 821: ldr r3, [r5, #MACHINFO_TYPE] @ get machine type 83 teq r3, r1 @ matches loader number? 84 beq 2f @ found 85 add r5, r5, #SIZEOF_MACHINE_DESC @ next machine_desc 86 cmp r5, r6 87 blo 1b 88 mov r5, #0 @ unknown machine 892: mov pc, lr 90ENDPROC(__lookup_machine_type) 91 92/* 93 * Look in arch/arm/kernel/arch.[ch] for information about the 94 * __arch_info structures. 95 */ 96 .align 2 97 .type __lookup_machine_type_data, %object 98__lookup_machine_type_data: 99 .long . 100 .long __arch_info_begin 101 .long __arch_info_end 102 .size __lookup_machine_type_data, . - __lookup_machine_type_data 103 104/* Determine validity of the r2 atags pointer. The heuristic requires 105 * that the pointer be aligned, in the first 16k of physical RAM and 106 * that the ATAG_CORE marker is first and present. Future revisions 107 * of this function may be more lenient with the physical address and 108 * may also be able to move the ATAGS block if necessary. 109 * 110 * r8 = machinfo 111 * 112 * Returns: 113 * r2 either valid atags pointer, or zero 114 * r5, r6 corrupted 115 */ 116__vet_atags: 117 tst r2, #0x3 @ aligned? 118 bne 1f 119 120 ldr r5, [r2, #0] @ is first tag ATAG_CORE? 121 cmp r5, #ATAG_CORE_SIZE 122 cmpne r5, #ATAG_CORE_SIZE_EMPTY 123 bne 1f 124 ldr r5, [r2, #4] 125 ldr r6, =ATAG_CORE 126 cmp r5, r6 127 bne 1f 128 129 mov pc, lr @ atag pointer is ok 130 1311: mov r2, #0 132 mov pc, lr 133ENDPROC(__vet_atags) 134 135/* 136 * The following fragment of code is executed with the MMU on in MMU mode, 137 * and uses absolute addresses; this is not position independent. 138 * 139 * r0 = cp#15 control register 140 * r1 = machine ID 141 * r2 = atags pointer 142 * r9 = processor ID 143 */ 144 __INIT 145__mmap_switched: 146 adr r3, __mmap_switched_data 147 148 ldmia r3!, {r4, r5, r6, r7} 149 cmp r4, r5 @ Copy data segment if needed 1501: cmpne r5, r6 151 ldrne fp, [r4], #4 152 strne fp, [r5], #4 153 bne 1b 154 155 mov fp, #0 @ Clear BSS (and zero fp) 1561: cmp r6, r7 157 strcc fp, [r6],#4 158 bcc 1b 159 160 ARM( ldmia r3, {r4, r5, r6, r7, sp}) 161 THUMB( ldmia r3, {r4, r5, r6, r7} ) 162 THUMB( ldr sp, [r3, #16] ) 163 str r9, [r4] @ Save processor ID 164 str r1, [r5] @ Save machine type 165 str r2, [r6] @ Save atags pointer 166 bic r4, r0, #CR_A @ Clear 'A' bit 167 stmia r7, {r0, r4} @ Save control register values 168 b start_kernel 169ENDPROC(__mmap_switched) 170 171 .align 2 172 .type __mmap_switched_data, %object 173__mmap_switched_data: 174 .long __data_loc @ r4 175 .long _sdata @ r5 176 .long __bss_start @ r6 177 .long _end @ r7 178 .long processor_id @ r4 179 .long __machine_arch_type @ r5 180 .long __atags_pointer @ r6 181 .long cr_alignment @ r7 182 .long init_thread_union + THREAD_START_SP @ sp 183 .size __mmap_switched_data, . - __mmap_switched_data 184 185/* 186 * This provides a C-API version of __lookup_machine_type 187 */ 188ENTRY(lookup_machine_type) 189 stmfd sp!, {r4 - r6, lr} 190 mov r1, r0 191 bl __lookup_machine_type 192 mov r0, r5 193 ldmfd sp!, {r4 - r6, pc} 194ENDPROC(lookup_machine_type) 195 196/* 197 * This provides a C-API version of __lookup_processor_type 198 */ 199ENTRY(lookup_processor_type) 200 stmfd sp!, {r4 - r6, r9, lr} 201 mov r9, r0 202 bl __lookup_processor_type 203 mov r0, r5 204 ldmfd sp!, {r4 - r6, r9, pc} 205ENDPROC(lookup_processor_type) 206 207/* 208 * Read processor ID register (CP#15, CR0), and look up in the linker-built 209 * supported processor list. Note that we can't use the absolute addresses 210 * for the __proc_info lists since we aren't running with the MMU on 211 * (and therefore, we are not in the correct address space). We have to 212 * calculate the offset. 213 * 214 * r9 = cpuid 215 * Returns: 216 * r3, r4, r6 corrupted 217 * r5 = proc_info pointer in physical address space 218 * r9 = cpuid (preserved) 219 */ 220 __CPUINIT 221__lookup_processor_type: 222 adr r3, __lookup_processor_type_data 223 ldmia r3, {r4 - r6} 224 sub r3, r3, r4 @ get offset between virt&phys 225 add r5, r5, r3 @ convert virt addresses to 226 add r6, r6, r3 @ physical address space 2271: ldmia r5, {r3, r4} @ value, mask 228 and r4, r4, r9 @ mask wanted bits 229 teq r3, r4 230 beq 2f 231 add r5, r5, #PROC_INFO_SZ @ sizeof(proc_info_list) 232 cmp r5, r6 233 blo 1b 234 mov r5, #0 @ unknown processor 2352: mov pc, lr 236ENDPROC(__lookup_processor_type) 237 238/* 239 * Look in <asm/procinfo.h> for information about the __proc_info structure. 240 */ 241 .align 2 242 .type __lookup_processor_type_data, %object 243__lookup_processor_type_data: 244 .long . 245 .long __proc_info_begin 246 .long __proc_info_end 247 .size __lookup_processor_type_data, . - __lookup_processor_type_data 248 249__error_p: 250#ifdef CONFIG_DEBUG_LL 251 adr r0, str_p1 252 bl printascii 253 mov r0, r9 254 bl printhex8 255 adr r0, str_p2 256 bl printascii 257 b __error 258str_p1: .asciz "\nError: unrecognized/unsupported processor variant (0x" 259str_p2: .asciz ").\n" 260 .align 261#endif 262ENDPROC(__error_p) 263 264__error: 265#ifdef CONFIG_ARCH_RPC 266/* 267 * Turn the screen red on a error - RiscPC only. 268 */ 269 mov r0, #0x02000000 270 mov r3, #0x11 271 orr r3, r3, r3, lsl #8 272 orr r3, r3, r3, lsl #16 273 str r3, [r0], #4 274 str r3, [r0], #4 275 str r3, [r0], #4 276 str r3, [r0], #4 277#endif 2781: mov r0, r0 279 b 1b 280ENDPROC(__error) 281