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/* 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>
/*
* 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 argc and argv */
xor r3, r3, r3
xor r4, r4, r4
.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 */
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