arch/m68knommu/platform/coldfire/head.S

   1 /*****************************************************************************/
   2
   3 /*
   4  *      head.S -- common startup code for ColdFire CPUs.
   5  *
   6  *      (C) Copyright 1999-2006, Greg Ungerer <gerg@snapgear.com>.
   7  */
   8
   9 /*****************************************************************************/
  10
  11 #include <linux/sys.h>
  12 #include <linux/linkage.h>
  13 #include <linux/init.h>
  14 #include <asm/asm-offsets.h>
  15 #include <asm/coldfire.h>
  16 #include <asm/mcfcache.h>
  17 #include <asm/mcfsim.h>
  18 #include <asm/thread_info.h>
  19
  20 /*****************************************************************************/
  21
  22 /*
  23  *      If we don't have a fixed memory size, then lets build in code
  24  *      to auto detect the DRAM size. Obviously this is the prefered
  25  *      method, and should work for most boards. It won't work for those
  26  *      that do not have their RAM starting at address 0, and it only
  27  *      works on SDRAM (not boards fitted with SRAM).
  28  */
  29 #if CONFIG_RAMSIZE != 0
  30 .macro GET_MEM_SIZE
  31         movel   #CONFIG_RAMSIZE,%d0     /* hard coded memory size */
  32 .endm
  33
  34 #elif defined(CONFIG_M5206) || defined(CONFIG_M5206e) || \
  35       defined(CONFIG_M5249) || defined(CONFIG_M527x) || \
  36       defined(CONFIG_M528x) || defined(CONFIG_M5307) || \
  37       defined(CONFIG_M5407)
  38 /*
  39  *      Not all these devices have exactly the same DRAM controller,
  40  *      but the DCMR register is virtually identical - give or take
  41  *      a couple of bits. The only exception is the 5272 devices, their
  42  *      DRAM controller is quite different.
  43  */
  44 .macro GET_MEM_SIZE
  45         movel   MCF_MBAR+MCFSIM_DMR0,%d0 /* get mask for 1st bank */
  46         btst    #0,%d0                  /* check if region enabled */
  47         beq     1f
  48         andl    #0xfffc0000,%d0
  49         beq     1f
  50         addl    #0x00040000,%d0         /* convert mask to size */
  51 1:
  52         movel   MCF_MBAR+MCFSIM_DMR1,%d1 /* get mask for 2nd bank */
  53         btst    #0,%d1                  /* check if region enabled */
  54         beq     2f
  55         andl    #0xfffc0000, %d1
  56         beq     2f
  57         addl    #0x00040000,%d1
  58         addl    %d1,%d0                 /* total mem size in d0 */
  59 2:
  60 .endm
  61
  62 #elif defined(CONFIG_M5272)
  63 .macro GET_MEM_SIZE
  64         movel   MCF_MBAR+MCFSIM_CSOR7,%d0 /* get SDRAM address mask */
  65         andil   #0xfffff000,%d0         /* mask out chip select options */
  66         negl    %d0                     /* negate bits */
  67 .endm
  68
  69 #elif defined(CONFIG_M520x)
  70 .macro GET_MEM_SIZE
  71         clrl    %d0
  72         movel   MCF_MBAR+MCFSIM_SDCS0, %d2 /* Get SDRAM chip select 0 config */
  73         andl    #0x1f, %d2              /* Get only the chip select size */
  74         beq     3f                      /* Check if it is enabled */
  75         addql   #1, %d2                 /* Form exponent */
  76         moveql  #1, %d0
  77         lsll    %d2, %d0                /* 2 ^ exponent */
  78 3:
  79         movel   MCF_MBAR+MCFSIM_SDCS1, %d2 /* Get SDRAM chip select 1 config */
  80         andl    #0x1f, %d2              /* Get only the chip select size */
  81         beq     4f                      /* Check if it is enabled */
  82         addql   #1, %d2                 /* Form exponent */
  83         moveql  #1, %d1
  84         lsll    %d2, %d1                /* 2 ^ exponent */
  85         addl    %d1, %d0                /* Total size of SDRAM in d0 */
  86 4:
  87 .endm
  88
  89 #else
  90 #error "ERROR: I don't know how to probe your boards memory size?"
  91 #endif
  92
  93 /*****************************************************************************/
  94
  95 /*
  96  *      Boards and platforms can do specific early hardware setup if
  97  *      they need to. Most don't need this, define away if not required.
  98  */
  99 #ifndef PLATFORM_SETUP
 100 #define PLATFORM_SETUP
 101 #endif
 102
 103 /*****************************************************************************/
 104
 105 .global _start
 106 .global _rambase
 107 .global _ramvec
 108 .global _ramstart
 109 .global _ramend
 110 #if defined(CONFIG_UBOOT)
 111 .global _init_sp
 112 #endif
 113
 114 /*****************************************************************************/
 115
 116 .data
 117
 118 /*
 119  *      During startup we store away the RAM setup. These are not in the
 120  *      bss, since their values are determined and written before the bss
 121  *      has been cleared.
 122  */
 123 _rambase:
 124 .long   0
 125 _ramvec:
 126 .long   0
 127 _ramstart:
 128 .long   0
 129 _ramend:
 130 .long   0
 131 #if defined(CONFIG_UBOOT)
 132 _init_sp:
 133 .long   0
 134 #endif
 135
 136 /*****************************************************************************/
 137
 138 __HEAD
 139
 140 /*
 141  *      This is the codes first entry point. This is where it all
 142  *      begins...
 143  */
 144
 145 _start:
 146         nop                                     /* filler */
 147         movew   #0x2700, %sr                    /* no interrupts */
 148 #if defined(CONFIG_UBOOT)
 149         movel   %sp,_init_sp                    /* save initial stack pointer */
 150 #endif
 151
 152         /*
 153          *      Do any platform or board specific setup now. Most boards
 154          *      don't need anything. Those exceptions are define this in
 155          *      their board specific includes.
 156          */
 157         PLATFORM_SETUP
 158
 159         /*
 160          *      Create basic memory configuration. Set VBR accordingly,
 161          *      and size memory.
 162          */
 163         movel   #CONFIG_VECTORBASE,%a7
 164         movec   %a7,%VBR                        /* set vectors addr */
 165         movel   %a7,_ramvec
 166
 167         movel   #CONFIG_RAMBASE,%a7             /* mark the base of RAM */
 168         movel   %a7,_rambase
 169
 170         GET_MEM_SIZE                            /* macro code determines size */
 171         addl    %a7,%d0
 172         movel   %d0,_ramend                     /* set end ram addr */
 173
 174         /*
 175          *      Now that we know what the memory is, lets enable cache
 176          *      and get things moving. This is Coldfire CPU specific.
 177          */
 178         CACHE_ENABLE                            /* enable CPU cache */
 179
 180
 181 #ifdef CONFIG_ROMFS_FS
 182         /*
 183          *      Move ROM filesystem above bss :-)
 184          */
 185         lea     _sbss,%a0                       /* get start of bss */
 186         lea     _ebss,%a1                       /* set up destination  */
 187         movel   %a0,%a2                         /* copy of bss start */
 188
 189         movel   8(%a0),%d0                      /* get size of ROMFS */
 190         addql   #8,%d0                          /* allow for rounding */
 191         andl    #0xfffffffc, %d0                /* whole words */
 192
 193         addl    %d0,%a0                         /* copy from end */
 194         addl    %d0,%a1                         /* copy from end */
 195         movel   %a1,_ramstart                   /* set start of ram */
 196
 197 _copy_romfs:
 198         movel   -(%a0),%d0                      /* copy dword */
 199         movel   %d0,-(%a1)
 200         cmpl    %a0,%a2                         /* check if at end */
 201         bne     _copy_romfs
 202
 203 #else /* CONFIG_ROMFS_FS */
 204         lea     _ebss,%a1
 205         movel   %a1,_ramstart
 206 #endif /* CONFIG_ROMFS_FS */
 207
 208
 209         /*
 210          *      Zero out the bss region.
 211          */
 212         lea     _sbss,%a0                       /* get start of bss */
 213         lea     _ebss,%a1                       /* get end of bss */
 214         clrl    %d0                             /* set value */
 215 _clear_bss:
 216         movel   %d0,(%a0)+                      /* clear each word */
 217         cmpl    %a0,%a1                         /* check if at end */
 218         bne     _clear_bss
 219
 220         /*
 221          *      Load the current task pointer and stack.
 222          */
 223         lea     init_thread_union,%a0
 224         lea     THREAD_SIZE(%a0),%sp
 225
 226         /*
 227          *      Assember start up done, start code proper.
 228          */
 229         jsr     start_kernel                    /* start Linux kernel */
 230
 231 _exit:
 232         jmp     _exit                           /* should never get here */
 233
 234 /*****************************************************************************/