flash_erase_block.c

Intel XScale PXA255 引导Linux的Redboot 版bootloader源代码！

//==========================================================================
//
//      flash_erase_block.c
//
//      Flash programming
//
//==========================================================================
//####COPYRIGHTBEGIN####
//                                                                          
// -------------------------------------------                              
// The contents of this file are subject to the Red Hat eCos Public License 
// Version 1.1 (the "License"); you may not use this file except in         
// compliance with the License.  You may obtain a copy of the License at    
// http://www.redhat.com/                                                   
//                                                                          
// Software distributed under the License is distributed on an "AS IS"      
// basis, WITHOUT WARRANTY OF ANY KIND, either express or implied.  See the 
// License for the specific language governing rights and limitations under 
// the License.                                                             
//                                                                          
// The Original Code is eCos - Embedded Configurable Operating System,      
// released September 30, 1998.                                             
//                                                                          
// The Initial Developer of the Original Code is Red Hat.                   
// Portions created by Red Hat are                                          
// Copyright (C) 1998, 1999, 2000 Red Hat, Inc.                             
// All Rights Reserved.                                                     
// -------------------------------------------                              
//                                                                          
//####COPYRIGHTEND####
//==========================================================================
//#####DESCRIPTIONBEGIN####
//
// Author(s):    gthomas
// Contributors: gthomas, msalter
// Date:         2000-07-14
// Purpose:      
// Description:  
//              
//####DESCRIPTIONEND####
//
//==========================================================================

#include "flash.h"

#include <pkgconf/hal.h>
#include <cyg/hal/hal_arch.h>
#include <cyg/hal/hal_cache.h>

//
// CAUTION!  This code must be copied to RAM before execution.  Therefore,
// it must not contain any code which might be position dependent!
//

int flash_erase_block(volatile unsigned char *block)
{
    volatile unsigned char *ROM;
    unsigned short stat;
    int timeout = 50000;
    int cache_on;
    int len;

    HAL_DCACHE_IS_ENABLED(cache_on);
    if (cache_on) {
        HAL_DCACHE_SYNC();
        HAL_DCACHE_DISABLE();
    }


    // First 4K page of flash at physcial address zero is
    // virtually mapped to address 0xa0000000.
    ROM = FLASH_P2V((unsigned)block & 0xFF800000);

    // Clear any error conditions
    ROM[0] = FLASH_Clear_Status;

    // Erase block
    ROM[0] = FLASH_Block_Erase;
    *FLASH_P2V(block) = FLASH_Confirm;
    timeout = 5000000;
    while(((stat = ROM[0]) & FLASH_Status_Ready) != FLASH_Status_Ready) {
        if (--timeout == 0) break;
    }

    // Restore ROM to "normal" mode
    ROM[0] = FLASH_Reset;

    // If an error was reported, see if the block erased anyway
    if (stat & 0x7E) {
        len = FLASH_BLOCK_SIZE;
        while (len > 0) {
	    if (*FLASH_P2V(block) != 0xFF)
		break;
	    block++;
            len -= sizeof(*block);
        }
        if (len == 0) stat = 0;
    }

    if (cache_on) {
        HAL_DCACHE_ENABLE();
    }

    return stat;
}