diff options
Diffstat (limited to 'arch/m68knommu/platform/coldfire')
| -rw-r--r-- | arch/m68knommu/platform/coldfire/head.S | 222 |
1 files changed, 222 insertions, 0 deletions
diff --git a/arch/m68knommu/platform/coldfire/head.S b/arch/m68knommu/platform/coldfire/head.S new file mode 100644 index 00000000000..b9aa0ca29bf --- /dev/null +++ b/arch/m68knommu/platform/coldfire/head.S @@ -0,0 +1,222 @@ +/*****************************************************************************/ + +/* + * 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 <asm/asm-offsets.h> +#include <asm/coldfire.h> +#include <asm/mcfcache.h> +#include <asm/mcfsim.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 + +/*****************************************************************************/ + +.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 + +/*****************************************************************************/ + +.text + +/* + * This is the codes first entry point. This is where it all + * begins... + */ + +_start: + nop /* filler */ + movew #0x2700, %sr /* no interrupts */ + + /* + * 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 */ + +/*****************************************************************************/ |