arch/arm/kernel/head-nommu.S

   1 /*
   2  *  linux/arch/arm/kernel/head-nommu.S
   3  *
   4  *  Copyright (C) 1994-2002 Russell King
   5  *  Copyright (C) 2003-2006 Hyok S. Choi
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License version 2 as
   9  * published by the Free Software Foundation.
  10  *
  11  *  Common kernel startup code (non-paged MM)
  12  *    for 32-bit CPUs which has a process ID register(CP15).
  13  *
  14  */
  15 #include <linux/config.h>
  16 #include <linux/linkage.h>
  17 #include <linux/init.h>
  18
  19 #include <asm/assembler.h>
  20 #include <asm/mach-types.h>
  21 #include <asm/procinfo.h>
  22 #include <asm/ptrace.h>
  23 #include <asm/thread_info.h>
  24 #include <asm/system.h>
  25
  26 #define PROCINFO_INITFUNC       12
  27 #define MACHINFO_TYPE           0
  28
  29 /*
  30  * Kernel startup entry point.
  31  * ---------------------------
  32  *
  33  * This is normally called from the decompressor code.  The requirements
  34  * are: MMU = off, D-cache = off, I-cache = dont care, r0 = 0,
  35  * r1 = machine nr.
  36  *
  37  * See linux/arch/arm/tools/mach-types for the complete list of machine
  38  * numbers for r1.
  39  *
  40  */
  41         __INIT
  42         .type   stext, %function
  43 ENTRY(stext)
  44         msr     cpsr_c, #PSR_F_BIT | PSR_I_BIT | MODE_SVC @ ensure svc mode
  45                                                 @ and irqs disabled
  46         mrc     p15, 0, r9, c0, c0              @ get processor id
  47         bl      __lookup_processor_type         @ r5=procinfo r9=cpuid
  48         movs    r10, r5                         @ invalid processor (r5=0)?
  49         beq     __error_p                               @ yes, error 'p'
  50         bl      __lookup_machine_type           @ r5=machinfo
  51         movs    r8, r5                          @ invalid machine (r5=0)?
  52         beq     __error_a                       @ yes, error 'a'
  53
  54         ldr     r13, __switch_data              @ address to jump to after
  55                                                 @ the initialization is done
  56         adr     lr, __after_proc_init           @ return (PIC) address
  57         add     pc, r10, #PROCINFO_INITFUNC
  58
  59 /*
  60  * Set the Control Register and Read the process ID.
  61  */
  62         .type   __after_proc_init, %function
  63 __after_proc_init:
  64         mrc     p15, 0, r0, c1, c0, 0           @ read control reg
  65 #ifdef CONFIG_ALIGNMENT_TRAP
  66         orr     r0, r0, #CR_A
  67 #else
  68         bic     r0, r0, #CR_A
  69 #endif
  70 #ifdef CONFIG_CPU_DCACHE_DISABLE
  71         bic     r0, r0, #CR_C
  72 #endif
  73 #ifdef CONFIG_CPU_BPREDICT_DISABLE
  74         bic     r0, r0, #CR_Z
  75 #endif
  76 #ifdef CONFIG_CPU_ICACHE_DISABLE
  77         bic     r0, r0, #CR_I
  78 #endif
  79         mcr     p15, 0, r0, c1, c0, 0           @ write control reg
  80
  81         mov     pc, r13                         @ clear the BSS and jump
  82                                                 @ to start_kernel
  83         .ltorg
  84
  85 #include "head-common.S"