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    /*
     * Copyright (c) 2004 Picture Elements, Inc.
     *    Stephen Williams (XXXXXXXXXXXXXXXX)
     *
     *    This source code is free software; you can redistribute it
     *    and/or modify it in source code form under the terms of the GNU
     *    General Public License as published by the Free Software
     *    Foundation; either version 2 of the License, or (at your option)
     *    any later version.
     *
     *    This program is distributed in the hope that it will be useful,
     *    but WITHOUT ANY WARRANTY; without even the implied warranty of
     *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
     *    GNU General Public License for more details.
     *
     *    You should have received a copy of the GNU General Public License
     *    along with this program; if not, write to the Free Software
     *    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
     */
    #ident "$Id:$"
    
    /*
     * The Xilinx SystemACE chip support is activated by defining
     * CONFIG_SYSTEMACE to turn on support, and CFG_SYSTEMACE_BASE
     * to set the base address of the device. This code currently
     * assumes that the chip is connected via a byte-wide bus.
     *
     * The CONFIG_SYSTEMACE also adds to fat support the device class
     * "ace" that allows the user to execute "fatls ace 0" and the
     * like. This works by making the systemace_get_dev function
     * available to cmd_fat.c:get_dev and filling in a block device
     * description that has all the bits needed for FAT support to
     * read sectors.
     */
    
    # include  <common.h>
    # include  <command.h>
    # include  <systemace.h>
    # include  <part.h>
    # include  <asm/io.h>
    
    #ifdef CONFIG_SYSTEMACE
    
    /*
     * The ace_readw and writew functions read/write 16bit words, but the
     * offset value is the BYTE offset as most used in the Xilinx
     * datasheet for the SystemACE chip. The CFG_SYSTEMACE_BASE is defined
     * to be the base address for the chip, usually in the local
     * peripheral bus.
     */
    static unsigned ace_readw(unsigned offset)
    {
          return readw(CFG_SYSTEMACE_BASE+offset);
    }
    
    static unsigned ace_writew(unsigned val, unsigned offset)
    {
          writew(val, CFG_SYSTEMACE_BASE+offset);
    }
    
    /* */
    
    static unsigned long systemace_read(int dev,
    				    unsigned long start,
    				    unsigned long blkcnt,
    				    unsigned long *buffer);
    
    static block_dev_desc_t systemace_dev = {0};
    
    static int get_cf_lock(void)
    {
          int retry = 10;
    
    	/* CONTROLREG = LOCKREG */
          ace_writew(0x0002, 0x18);
    
    	/* Wait for MPULOCK in STATUSREG[15:0] */
          while (! (ace_readw(0x04) & 0x0002)) {
    
    	    if (retry < 0)
    		  return -1;
    
    	    udelay(100000);
    	    retry -= 1;
          }
    
          return 0;
    }
    
    static void release_cf_lock(void)
    {
    	/* CONTROLREG = none */
          ace_writew(0x0000, 0x18);
    }
    
    block_dev_desc_t *  systemace_get_dev(int dev)
    {
    	/* The first time through this, the systemace_dev object is
    	   not yet initialized. In that case, fill it in. */
          if (systemace_dev.blksz == 0) {
    	    systemace_dev.if_type   = IF_TYPE_UNKNOWN;
    	    systemace_dev.part_type = PART_TYPE_UNKNOWN;
    	    systemace_dev.type      = DEV_TYPE_HARDDISK;
    	    systemace_dev.blksz     = 512;
    	    systemace_dev.removable = 1;
    	    systemace_dev.block_read = systemace_read;
          }
    
          return &systemace_dev;
    }
    
    /*
     * This function is called (by dereferencing the block_read pointer in
     * the dev_desc) to read blocks of data. The return value is the
     * number of blocks read. A zero return indicates an error.
     */
    static unsigned long systemace_read(int dev,
    				    unsigned long start,
    				    unsigned long blkcnt,
    				    unsigned long *buffer)
    {
          unsigned val;
          int retry;
    
          unsigned blk_countdown;
    
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          unsigned char*dp = (unsigned char*)buffer;
    
          if (get_cf_lock() < 0) {
    	    unsigned status = ace_readw(0x04);
    
    	      /* If CFDETECT is false, card is missing. */
    	    if (! (status&0x0010)) {
    		  printf("** CompactFlash card not present. **\n");
    		  return 0;
    	    }
    
    	    printf("**** ACE locked away from me (STATUSREG=%04x)\n", status);
    	    return 0;
          }
    
    
    #ifdef DEBUG_SYSTEMACE
          printf("... systemace read %lu sectors at %lu\n", blkcnt, start);
    #endif
    
    
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          retry = 2000;
          for (;;) {
    	    unsigned val = ace_readw(0x04);
    
    	      /* If CFDETECT is false, card is missing. */
    	    if (! (val & 0x0010)) {
    		  printf("**** ACE CompactFlash not found.\n");
    		  release_cf_lock();
    		  return 0;
    	    }
    
    	      /* If RDYFORCMD, then we are ready to go. */
    	    if (val & 0x0100)
    		  break;
    
    	    if (retry < 0) {
    		  printf("**** SystemACE not ready.\n");
    		  release_cf_lock();
    		  return 0;
    	    }
    
    	    udelay(1000);
    	    retry -= 1;
          }
    
    
    	/* The SystemACE can only transfer 256 sectors at a time, so
    	   limit the current chunk of sectors. The blk_countdown
    	   variable is the number of sectors left to transfer. */
    
          blk_countdown = blkcnt;
          while (blk_countdown > 0) {
    	    unsigned trans = blk_countdown;
    
    	    if (trans > 256) trans = 256;
    
    #ifdef DEBUG_SYSTEMACE
    	    printf("... transfer %lu sector in a chunk\n", trans);
    #endif
    	      /* Write LBA block address */
    	    ace_writew((start>> 0) & 0xffff, 0x10);
    	    ace_writew((start>>16) & 0x00ff, 0x12);
    
    	      /* NOTE: in the Write Sector count below, a count of 0
    		 causes a transfer of 256, so &0xff gives the right
    		 value for whatever transfer count we want. */
    
    	      /* Write sector count | ReadMemCardData. */
    	    ace_writew((trans&0xff) | 0x0300, 0x14);
    
    	    retry = trans * 16;
    	    while (retry > 0) {
    		  int idx;
    
    		    /* Wait for buffer to become ready. */
    		  while (! (ace_readw(0x04) & 0x0020)) {
    
    		  }
    
    		    /* Read 16 words of 2bytes from the sector buffer. */
    		  for (idx = 0 ;  idx < 16 ;  idx += 1) {
    			unsigned short val = ace_readw(0x40);
    			*dp++ = val & 0xff;
    			*dp++ = (val>>8) & 0xff;
    		  }
    
    		  retry -= 1;
    
    	      /* Count the blocks we transfer this time. */
    	    start += trans;
    	    blk_countdown -= trans;
    
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          }
    
          release_cf_lock();
    
          return blkcnt;
    }
    #endif