arch/m68k/68000/head.S

   1 /*
   2  * head.S - Common startup code for 68000 core based CPU's
   3  *
   4  * 2012.10.21, Luis Alves <ljalvs@gmail.com>, Single head.S file for all
   5  *             68000 core based CPU's. Based on the sources from:
   6  *             Coldfire by Greg Ungerer <gerg@snapgear.com>
   7  *             68328 by D. Jeff Dionne <jeff@ryeham.ee.ryerson.ca>,
   8  *                      Kenneth Albanowski <kjahds@kjahds.com>,
   9  *                      The Silver Hammer Group, Ltd.
  10  *
  11  */
  12
  13 #include <linux/linkage.h>
  14 #include <linux/init.h>
  15 #include <asm/asm-offsets.h>
  16 #include <asm/thread_info.h>
  17
  18
  19 /*****************************************************************************
  20  * UCSIMM and UCDIMM use CONFIG_MEMORY_RESERVE to reserve some RAM
  21  *****************************************************************************/
  22 #ifdef CONFIG_MEMORY_RESERVE
  23 #define RAMEND (CONFIG_RAMBASE+CONFIG_RAMSIZE)-(CONFIG_MEMORY_RESERVE*0x100000)
  24 #else
  25 #define RAMEND (CONFIG_RAMBASE+CONFIG_RAMSIZE)
  26 #endif
  27 /*****************************************************************************/
  28
  29 .global _start
  30 .global _rambase
  31 .global _ramvec
  32 .global _ramstart
  33 .global _ramend
  34
  35 #if defined(CONFIG_PILOT) || defined(CONFIG_INIT_LCD)
  36 .global bootlogo_bits
  37 #endif
  38
  39 /* Defining DEBUG_HEAD_CODE, serial port in 68x328 is inited */
  40 /* #define DEBUG_HEAD_CODE */
  41 #undef DEBUG_HEAD_CODE
  42
  43 .data
  44
  45 /*****************************************************************************
  46  * RAM setup pointers. Used by the kernel to determine RAM location and size.
  47  *****************************************************************************/
  48
  49 _rambase:
  50         .long   0
  51 _ramvec:
  52         .long   0
  53 _ramstart:
  54         .long   0
  55 _ramend:
  56         .long   0
  57
  58 __HEAD
  59
  60 /*****************************************************************************
  61  * Entry point, where all begins!
  62  *****************************************************************************/
  63
  64 _start:
  65
  66 /* Pilot need this specific signature at the start of ROM */
  67 #ifdef CONFIG_PILOT
  68         .byte   0x4e, 0xfa, 0x00, 0x0a          /* bra opcode (jmp 10 bytes) */
  69         .byte   'b', 'o', 'o', 't'
  70         .word   10000
  71         nop
  72         moveq   #0, %d0
  73         movew   %d0, 0xfffff618                 /* Watchdog off */
  74         movel   #0x00011f07, 0xfffff114         /* CS A1 Mask */
  75 #endif /* CONFIG_PILOT */
  76
  77         movew   #0x2700, %sr                    /* disable all interrupts */
  78
  79 /*****************************************************************************
  80  * Setup PLL and wait for it to settle (in 68x328 cpu's).
  81  * Also, if enabled, init serial port.
  82  *****************************************************************************/
  83 #if defined(CONFIG_M68328) || \
  84     defined(CONFIG_M68EZ328) || \
  85     defined(CONFIG_M68VZ328)
  86
  87 /* Serial port setup. Should only be needed if debugging this startup code. */
  88 #ifdef DEBUG_HEAD_CODE
  89         movew   #0x0800, 0xfffff906             /* Ignore CTS */
  90         movew   #0x010b, 0xfffff902             /* BAUD to 9600 */
  91         movew   #0xe100, 0xfffff900             /* enable */
  92 #endif /* DEBUG_HEAD */
  93
  94 #ifdef CONFIG_PILOT
  95         movew   #0x2410, 0xfffff200             /* PLLCR */
  96 #else
  97         movew   #0x2400, 0xfffff200             /* PLLCR */
  98 #endif
  99         movew   #0x0123, 0xfffff202             /* PLLFSR */
 100         moveq   #0, %d0
 101         movew   #16384, %d0                     /* PLL settle wait loop */
 102 _pll_settle:
 103         subw    #1, %d0
 104         bne     _pll_settle
 105 #endif /* CONFIG_M68x328 */
 106
 107
 108 /*****************************************************************************
 109  * If running kernel from ROM some specific initialization has to be done.
 110  * (Assuming that everything is already init'ed when running from RAM)
 111  *****************************************************************************/
 112 #ifdef CONFIG_ROMKERNEL
 113
 114 /*****************************************************************************
 115  * Init chip registers (uCsimm specific)
 116  *****************************************************************************/
 117 #ifdef CONFIG_UCSIMM
 118         moveb   #0x00, 0xfffffb0b       /* Watchdog off */
 119         moveb   #0x10, 0xfffff000       /* SCR */
 120         moveb   #0x00, 0xfffff40b       /* enable chip select */
 121         moveb   #0x00, 0xfffff423       /* enable /DWE */
 122         moveb   #0x08, 0xfffffd0d       /* disable hardmap */
 123         moveb   #0x07, 0xfffffd0e       /* level 7 interrupt clear */
 124         movew   #0x8600, 0xfffff100     /* FLASH at 0x10c00000 */
 125         movew   #0x018b, 0xfffff110     /* 2Meg, enable, 0ws */
 126         movew   #0x8f00, 0xfffffc00     /* DRAM configuration */
 127         movew   #0x9667, 0xfffffc02     /* DRAM control */
 128         movew   #0x0000, 0xfffff106     /* DRAM at 0x00000000 */
 129         movew   #0x068f, 0xfffff116     /* 8Meg, enable, 0ws */
 130         moveb   #0x40, 0xfffff300       /* IVR */
 131         movel   #0x007FFFFF, %d0        /* IMR */
 132         movel   %d0, 0xfffff304
 133         moveb   0xfffff42b, %d0
 134         andb    #0xe0, %d0
 135         moveb   %d0, 0xfffff42b
 136 #endif
 137
 138 /*****************************************************************************
 139  * Init LCD controller.
 140  * (Assuming that LCD controller is already init'ed when running from RAM)
 141  *****************************************************************************/
 142 #ifdef CONFIG_INIT_LCD
 143 #ifdef CONFIG_PILOT
 144         moveb   #0, 0xfffffA27                  /* LCKCON */
 145         movel   #_start, 0xfffffA00             /* LSSA */
 146         moveb   #0xa, 0xfffffA05                /* LVPW */
 147         movew   #0x9f, 0xFFFFFa08               /* LXMAX */
 148         movew   #0x9f, 0xFFFFFa0a               /* LYMAX */
 149         moveb   #9, 0xfffffa29                  /* LBAR */
 150         moveb   #0, 0xfffffa25                  /* LPXCD */
 151         moveb   #0x04, 0xFFFFFa20               /* LPICF */
 152         moveb   #0x58, 0xfffffA27               /* LCKCON */
 153         moveb   #0x85, 0xfffff429               /* PFDATA */
 154         moveb   #0xd8, 0xfffffA27               /* LCKCON */
 155         moveb   #0xc5, 0xfffff429               /* PFDATA */
 156         moveb   #0xd5, 0xfffff429               /* PFDATA */
 157         movel   #bootlogo_bits, 0xFFFFFA00      /* LSSA */
 158         moveb   #10, 0xFFFFFA05                 /* LVPW */
 159         movew   #160, 0xFFFFFA08                /* LXMAX */
 160         movew   #160, 0xFFFFFA0A                /* LYMAX */
 161 #else /* CONFIG_PILOT */
 162         movel   #bootlogo_bits, 0xfffffA00      /* LSSA */
 163         moveb   #0x28, 0xfffffA05               /* LVPW */
 164         movew   #0x280, 0xFFFFFa08              /* LXMAX */
 165         movew   #0x1df, 0xFFFFFa0a              /* LYMAX */
 166         moveb   #0, 0xfffffa29                  /* LBAR */
 167         moveb   #0, 0xfffffa25                  /* LPXCD */
 168         moveb   #0x08, 0xFFFFFa20               /* LPICF */
 169         moveb   #0x01, 0xFFFFFA21               /* -ve pol */
 170         moveb   #0x81, 0xfffffA27               /* LCKCON */
 171         movew   #0xff00, 0xfffff412             /* LCD pins */
 172 #endif /* CONFIG_PILOT */
 173 #endif /* CONFIG_INIT_LCD */
 174
 175 /*****************************************************************************
 176  * Kernel is running from FLASH/ROM (XIP)
 177  * Copy init text & data to RAM
 178  *****************************************************************************/
 179         moveal  #_etext, %a0
 180         moveal  #_sdata, %a1
 181         moveal  #__bss_start, %a2
 182 _copy_initmem:
 183         movel   %a0@+, %a1@+
 184         cmpal   %a1, %a2
 185         bhi     _copy_initmem
 186 #endif /* CONFIG_ROMKERNEL */
 187
 188 /*****************************************************************************
 189  * Setup basic memory information for kernel
 190  *****************************************************************************/
 191         movel   #CONFIG_VECTORBASE,_ramvec      /* set vector base location */
 192         movel   #CONFIG_RAMBASE,_rambase        /* set the base of RAM */
 193         movel   #RAMEND, _ramend                /* set end ram addr */
 194         lea     __bss_stop,%a1
 195         movel   %a1,_ramstart
 196
 197 /*****************************************************************************
 198  * If the kernel is in RAM, move romfs to right above bss and
 199  * adjust _ramstart to where romfs ends.
 200  *
 201  * (Do this only if CONFIG_MTD_UCLINUX is true)
 202  *****************************************************************************/
 203
 204 #if defined(CONFIG_ROMFS_FS) && defined(CONFIG_RAMKERNEL) && \
 205     defined(CONFIG_MTD_UCLINUX)
 206         lea     __bss_start, %a0                /* get start of bss */
 207         lea     __bss_stop, %a1                 /* set up destination  */
 208         movel   %a0, %a2                        /* copy of bss start */
 209
 210         movel   8(%a0), %d0                     /* get size of ROMFS */
 211         addql   #8, %d0                         /* allow for rounding */
 212         andl    #0xfffffffc, %d0                /* whole words */
 213
 214         addl    %d0, %a0                        /* copy from end */
 215         addl    %d0, %a1                        /* copy from end */
 216         movel   %a1, _ramstart                  /* set start of ram */
 217 _copy_romfs:
 218         movel   -(%a0), -(%a1)                  /* copy dword */
 219         cmpl    %a0, %a2                        /* check if at end */
 220         bne     _copy_romfs
 221 #endif /* CONFIG_ROMFS_FS && CONFIG_RAMKERNEL && CONFIG_MTD_UCLINUX */
 222
 223 /*****************************************************************************
 224  * Clear bss region
 225  *****************************************************************************/
 226         lea     __bss_start, %a0                /* get start of bss */
 227         lea     __bss_stop, %a1                 /* get end of bss */
 228 _clear_bss:
 229         movel   #0, (%a0)+                      /* clear each word */
 230         cmpl    %a0, %a1                        /* check if at end */
 231         bne     _clear_bss
 232
 233 /*****************************************************************************
 234  * Load the current task pointer and stack.
 235  *****************************************************************************/
 236         lea     init_thread_union,%a0
 237         lea     THREAD_SIZE(%a0),%sp
 238         jsr     start_kernel                    /* start Linux kernel */
 239 _exit:
 240         jmp     _exit                           /* should never get here */