/*****************************************************************************/ /* * head.S -- common startup code for ColdFire CPUs. * * (C) Copyright 1999-2010, Greg Ungerer . */ /*****************************************************************************/ #include #include #include #include #include #include #include /*****************************************************************************/ /* * 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. Not * all version cores have identical cache register setup. But * it is very similar. Define the exact settings in the headers * then the code here is the same for all. */ movel #CACHE_INIT,%d0 /* invalidate whole cache */ movec %d0,%CACR nop movel #ACR0_MODE,%d0 /* set RAM region for caching */ movec %d0,%ACR0 movel #ACR1_MODE,%d0 /* anything else to cache? */ movec %d0,%ACR1 #ifdef ACR2_MODE movel #ACR2_MODE,%d0 movec %d0,%ACR2 movel #ACR3_MODE,%d0 movec %d0,%ACR3 #endif movel #CACHE_MODE,%d0 /* enable cache */ movec %d0,%CACR nop #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 */ /*****************************************************************************/