source: rtems/c/src/lib/libbsp/powerpc/mpc8260ads/start/start.S @ 820d1ab0

/*  start.S
 *
 *  $Id$
 *
 *  Modified for the Motorola PQII ADS board by
 *  Andy Dachs <a.dachs@sstl.co.uk> 23-11-00.
 *  Surrey Satellite Technology Limited
 *
 *  I have a proprietary bootloader programmed into the flash
 *  on the board which initialises the SDRAM prior to calling
 *  this function.
 *
 *  This file is based on the one by Jay Monkman (jmonkman@fracsa.com)
 *  which in turn was based on the dlentry.s file for the Papyrus BSP,
 *  written by:
 *
 *  Author:     Andrew Bray <andy@i-cubed.co.uk>
 *
 *  COPYRIGHT (c) 1995 by i-cubed ltd.
 *
 *  To anyone who acknowledges that this file is provided "AS IS"
 *  without any express or implied warranty:
 *      permission to use, copy, modify, and distribute this file
 *      for any purpose is hereby granted without fee, provided that
 *      the above copyright notice and this notice appears in all
 *      copies, and that the name of i-cubed limited not be used in
 *      advertising or publicity pertaining to distribution of the
 *      software without specific, written prior permission.
 *      i-cubed limited makes no representations about the suitability
 *      of this software for any purpose.
 *
 */

#include <rtems/asm.h>

#warning Call to boot_card has changed and needs checking.
#warning The call is "void boot_card(const char* cmdline);"
#warning You need to pass a NULL.
#warning Please check and remove these warnings.
        
/*
 *  The initial stack is set to run BELOW the code base address.
 *  (between the vectors and text sections)
 *
 *  The entry veneer has to clear the BSS and copy the read only
 *  version of the data segment to the correct location.
 */

        .section ".entry"  /* This might have to be the first thing in the
                            * text section. At one time, it had to be
                            * first, but I don't believe it is true
                            * any more. */
        PUBLIC_VAR (start)
SYM(start):
        bl      .startup
base_addr:

/*
 * Parameters from linker
 */
toc_pointer:
        .long   s.got
bss_length:
        .long   bss.size
bss_addr:
        .long   bss.start

PUBLIC_VAR (data_length )
data_length:
        .long   data.size
PUBLIC_VAR (data_addr )
data_addr:
        .long   data.start

PUBLIC_VAR (text_addr)
text_addr:
        .long   text.start

PUBLIC_VAR (text_length)
text_length:
        .long   text.size

/*
 * Initialization code
 */
.startup:
    /* Get start address */
        mflr    r1

    /* --------------------------------------------------
     * Clear MSR[EE] to disable interrupts
     * Clear MSR[IP] bit to put vectors at 0x00000000
     * Set MSR[FP] to enable FPU - not on my eval board!
     * -------------------------------------------------- */
        mfmsr   r5
        lis     r13, 0xFFFF
        ori     r13, r13, 0x7FBF
        and     r5, r5, r13                     /* Clear EE and IP */
#if 1
        ori     r5, r5, 0x2000                  /* Enable FPU */
#endif
        mtmsr   r5

#ifdef ENABLE_CACHE
        /* Enable caches */
        mfspr   r5, 1008
        ori     r5, r5, 0x8000
        isync
        mtspr   1008, r5

/*      Leave D-cache disabled for now */
#if 0
        ori     r5, r5, 0x4000
        sync
        mtspr   1008, r5
#endif
#endif

        /*--------------------------------------------------
         * Set up the power management modes
         * The 8260 has a dynamic power management mode that
         * is automatically invoked if the unit is idle.
         * We invoke the NAP mode in the RTEMS idle task.
         *-------------------------------------------------- */

        lis     r13, 0x0050     /* set nap mode and DPM */
        or      r5, r5, r13
        mtspr   1008, r5

        /*--------------------------------------------------
         *
         *-------------------------------------------------- */

        /* clear the bss section */
        bl      bssclr

/*
 * C_setup.
 */

        /* set toc */
        lwz r2, toc_pointer-base_addr(r1)

        /* Set up stack pointer = beginning of text section - 56 */
        addi    r1, r1, -56-4

        /* Clear cmdline */
        xor r3, r3, r3

        .extern SYM (boot_card)
        bl       SYM (boot_card)        /* call the first C routine */

        /* we don't expect to return from boot_card but if we do */
        /* wait here for watchdog to kick us into hard reset     */

twiddle:
        b               twiddle

/*
 * bssclr - zero out bss
 */
bssclr:
        lwz     r4, bss_addr-base_addr(r1)      /* Start of bss */
        lwz     r5, bss_length-base_addr(r1)    /* Length of bss */

        rlwinm. r5,r5,30,0x3FFFFFFF             /* form length/4 */
        beqlr                                   /* no bss */
        mtctr   r5                              /* set ctr reg */
        xor     r6,r6,r6                        /* r6 = 0 */
clear_bss:
        stswi   r6,r4,0x4                       /* store r6 */
        addi    r4,r4,0x4                       /* update r2 */

        bdnz    clear_bss                       /* dec counter and loop */
        blr                                     /* return */