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/*****************************************************************************/
/*
* head.S -- common startup code for ColdFire CPUs.
*
* (C) Copyright 1999-2006, Greg Ungerer <gerg@snapgear.com>.
*/
/*****************************************************************************/
#include <linux/sys.h>
#include <linux/linkage.h>
#include <linux/init.h>
#include <asm/asm-offsets.h>
#include <asm/coldfire.h>
#include <asm/mcfcache.h>
#include <asm/mcfsim.h>
#include <asm/thread_info.h>
/*****************************************************************************/
/*
* If we don't have a fixed memory size, then lets build in code
* to auto detect the DRAM size. Obviously this is the prefered
* method, and should work for most boards. It won't work for those
* that do not have their RAM starting at address 0, and it only
* works on SDRAM (not boards fitted with SRAM).
*/
#if CONFIG_RAMSIZE != 0
.macro GET_MEM_SIZE
movel #CONFIG_RAMSIZE,%d0 /* hard coded memory size */
.endm
#elif defined(CONFIG_M5206) || defined(CONFIG_M5206e) || \
defined(CONFIG_M5249) || defined(CONFIG_M527x) || \
defined(CONFIG_M528x) || defined(CONFIG_M5307) || \
defined(CONFIG_M5407)
/*
* Not all these devices have exactly the same DRAM controller,
* but the DCMR register is virtually identical - give or take
* a couple of bits. The only exception is the 5272 devices, their
* DRAM controller is quite different.
*/
.macro GET_MEM_SIZE
movel MCF_MBAR+MCFSIM_DMR0,%d0 /* get mask for 1st bank */
btst #0,%d0 /* check if region enabled */
beq 1f
andl #0xfffc0000,%d0
beq 1f
addl #0x00040000,%d0 /* convert mask to size */
1:
movel MCF_MBAR+MCFSIM_DMR1,%d1 /* get mask for 2nd bank */
btst #0,%d1 /* check if region enabled */
beq 2f
andl #0xfffc0000, %d1
beq 2f
addl #0x00040000,%d1
addl %d1,%d0 /* total mem size in d0 */
2:
.endm
#elif defined(CONFIG_M5272)
.macro GET_MEM_SIZE
movel MCF_MBAR+MCFSIM_CSOR7,%d0 /* get SDRAM address mask */
andil #0xfffff000,%d0 /* mask out chip select options */
negl %d0 /* negate bits */
.endm
#elif defined(CONFIG_M520x)
.macro GET_MEM_SIZE
clrl %d0
movel MCF_MBAR+MCFSIM_SDCS0, %d2 /* Get SDRAM chip select 0 config */
andl #0x1f, %d2 /* Get only the chip select size */
beq 3f /* Check if it is enabled */
addql #1, %d2 /* Form exponent */
moveql #1, %d0
lsll %d2, %d0 /* 2 ^ exponent */
3:
movel MCF_MBAR+MCFSIM_SDCS1, %d2 /* Get SDRAM chip select 1 config */
andl #0x1f, %d2 /* Get only the chip select size */
beq 4f /* Check if it is enabled */
addql #1, %d2 /* Form exponent */
moveql #1, %d1
lsll %d2, %d1 /* 2 ^ exponent */
addl %d1, %d0 /* Total size of SDRAM in d0 */
4:
.endm
#else
#error "ERROR: I don't know how to probe your boards memory size?"
#endif
/*****************************************************************************/
/*
* Boards and platforms can do specific early hardware setup if
* they need to. Most don't need this, define away if not required.
*/
#ifndef PLATFORM_SETUP
#define PLATFORM_SETUP
#endif
/*****************************************************************************/
.global _start
.global _rambase
.global _ramvec
.global _ramstart
.global _ramend
#if defined(CONFIG_UBOOT)
.global _init_sp
#endif
/*****************************************************************************/
.data
/*
* During startup we store away the RAM setup. These are not in the
* bss, since their values are determined and written before the bss
* has been cleared.
*/
_rambase:
.long 0
_ramvec:
.long 0
_ramstart:
.long 0
_ramend:
.long 0
#if defined(CONFIG_UBOOT)
_init_sp:
.long 0
#endif
/*****************************************************************************/
__HEAD
/*
* This is the codes first entry point. This is where it all
* begins...
*/
_start:
nop /* filler */
movew #0x2700, %sr /* no interrupts */
#if defined(CONFIG_UBOOT)
movel %sp,_init_sp /* save initial stack pointer */
#endif
/*
* Do any platform or board specific setup now. Most boards
* don't need anything. Those exceptions are define this in
* their board specific includes.
*/
PLATFORM_SETUP
/*
* Create basic memory configuration. Set VBR accordingly,
* and size memory.
*/
movel #CONFIG_VECTORBASE,%a7
movec %a7,%VBR /* set vectors addr */
movel %a7,_ramvec
movel #CONFIG_RAMBASE,%a7 /* mark the base of RAM */
movel %a7,_rambase
GET_MEM_SIZE /* macro code determines size */
addl %a7,%d0
movel %d0,_ramend /* set end ram addr */
/*
* Now that we know what the memory is, lets enable cache
* and get things moving. This is Coldfire CPU specific.
*/
CACHE_ENABLE /* enable CPU cache */
#ifdef CONFIG_ROMFS_FS
/*
* Move ROM filesystem above bss :-)
*/
lea _sbss,%a0 /* get start of bss */
lea _ebss,%a1 /* set up destination */
movel %a0,%a2 /* copy of bss start */
movel 8(%a0),%d0 /* get size of ROMFS */
addql #8,%d0 /* allow for rounding */
andl #0xfffffffc, %d0 /* whole words */
addl %d0,%a0 /* copy from end */
addl %d0,%a1 /* copy from end */
movel %a1,_ramstart /* set start of ram */
_copy_romfs:
movel -(%a0),%d0 /* copy dword */
movel %d0,-(%a1)
cmpl %a0,%a2 /* check if at end */
bne _copy_romfs
#else /* CONFIG_ROMFS_FS */
lea _ebss,%a1
movel %a1,_ramstart
#endif /* CONFIG_ROMFS_FS */
/*
* Zero out the bss region.
*/
lea _sbss,%a0 /* get start of bss */
lea _ebss,%a1 /* get end of bss */
clrl %d0 /* set value */
_clear_bss:
movel %d0,(%a0)+ /* clear each word */
cmpl %a0,%a1 /* check if at end */
bne _clear_bss
/*
* Load the current task pointer and stack.
*/
lea init_thread_union,%a0
lea THREAD_SIZE(%a0),%sp
/*
* Assember start up done, start code proper.
*/
jsr start_kernel /* start Linux kernel */
_exit:
jmp _exit /* should never get here */
/*****************************************************************************/
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