arch/arm/kernel/head-common.S

   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
  40 1:      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)
  46 1:      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
  73 str_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
  92 1:      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
 107 str_a1: .asciz  "\nError: unrecognized/unsupported machine ID (r1 = 0x"
 108 str_a2: .asciz  ").\n\nAvailable machine support:\n\nID (hex)\tNAME\n"
 109 str_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
 128 1:      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
 152 1:      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
 160 2:      mov     pc, lr
 161
 162 /*
 163  * This provides a C-API version of the above function.
 164  */
 165 ENTRY(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
 178 3:      .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
 200 1:      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
 207 2:      mov     pc, lr
 208
 209 /*
 210  * This provides a C-API version of the above function.
 211  */
 212 ENTRY(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}