eeprom.c

优龙2410linux2.6.8内核源代码

   case 0:
     file->f_pos = offset;
     break;
   case 1:
     file->f_pos += offset;
     break;
   case 2:
     file->f_pos = eeprom.size - offset;
     break;
   default:
     return -EINVAL;
  }

  /* truncate position */
  if (file->f_pos < 0)
  {
    file->f_pos = 0;    
    return(-EOVERFLOW);
  }
  
  if (file->f_pos >= eeprom.size)
  {
    file->f_pos = eeprom.size - 1;
    return(-EOVERFLOW);
  }

  return ( file->f_pos );
}

/* Reads data from eeprom. */

static int eeprom_read_buf(loff_t addr, char * buf, int count)
{
  struct file f;

  f.f_pos = addr;
  return eeprom_read(&f, buf, count, &addr);
}



/* Reads data from eeprom. */

static ssize_t eeprom_read(struct file * file, char * buf, size_t count, loff_t *off)
{
  int read=0;
  unsigned long p = file->f_pos;

  unsigned char page;

  if(p >= eeprom.size)  /* Address i 0 - (size-1) */
  {
    return -EFAULT;
  }
  
  while(eeprom.busy)
  {
    interruptible_sleep_on(&eeprom.wait_q);

    /* bail out if we get interrupted */
    if (signal_pending(current))
      return -EINTR;
    
  }
  eeprom.busy++;

  page = (unsigned char) (p >> 8);
  
  if(!eeprom_address(p))
  {
    printk(KERN_INFO "%s: Read failed to address the eeprom: "
           "0x%08X (%i) page: %i\n", eeprom_name, (int)p, (int)p, page);
    i2c_stop();
    
    /* don't forget to wake them up */
    eeprom.busy--;
    wake_up_interruptible(&eeprom.wait_q);  
    return -EFAULT;
  }

  if( (p + count) > eeprom.size)
  {
    /* truncate count */
    count = eeprom.size - p;
  }

  /* stop dummy write op and initiate the read op */
  i2c_start();

  /* special case for small eeproms */
  if(eeprom.size < EEPROM_16KB)
  {
    i2c_outbyte( eeprom.select_cmd | 1 | (page << 1) );
  }

  /* go on with the actual read */
  read = read_from_eeprom( buf, count);
  
  if(read > 0)
  {
    file->f_pos += read;
  }

  eeprom.busy--;
  wake_up_interruptible(&eeprom.wait_q);
  return read;
}

/* Writes data to eeprom. */

static int eeprom_write_buf(loff_t addr, const char * buf, int count)
{
  struct file f;

  f.f_pos = addr;
  
  return eeprom_write(&f, buf, count, &addr);
}


/* Writes data to eeprom. */

static ssize_t eeprom_write(struct file * file, const char * buf, size_t count,
                            loff_t *off)
{
  int i, written, restart=1;
  unsigned long p;

  if (verify_area(VERIFY_READ, buf, count))
  {
    return -EFAULT;
  }

  while(eeprom.busy)
  {
    interruptible_sleep_on(&eeprom.wait_q);
    /* bail out if we get interrupted */
    if (signal_pending(current))
      return -EINTR;
  }
  eeprom.busy++;
  for(i = 0; (i < EEPROM_RETRIES) && (restart > 0); i++)
  {
    restart = 0;
    written = 0;
    p = file->f_pos;
   
    
    while( (written < count) && (p < eeprom.size))
    {
      /* address the eeprom */
      if(!eeprom_address(p))
      {
        printk(KERN_INFO "%s: Write failed to address the eeprom: "
               "0x%08X (%i) \n", eeprom_name, (int)p, (int)p);
        i2c_stop();
        
        /* don't forget to wake them up */
        eeprom.busy--;
        wake_up_interruptible(&eeprom.wait_q);
        return -EFAULT;
      }
#ifdef EEPROM_ADAPTIVE_TIMING      
      /* Adaptive algorithm to adjust timing */
      if (eeprom.retry_cnt_addr > 0)
      {
        /* To Low now */
        D(printk(">D=%i d=%i\n",
               eeprom.usec_delay_writecycles, eeprom.usec_delay_step));

        if (eeprom.usec_delay_step < 4)
        {
          eeprom.usec_delay_step++;
          eeprom.usec_delay_writecycles += eeprom.usec_delay_step;
        }
        else
        {

          if (eeprom.adapt_state > 0)
          {
            /* To Low before */
            eeprom.usec_delay_step *= 2;
            if (eeprom.usec_delay_step > 2)
            {
              eeprom.usec_delay_step--;
            }
            eeprom.usec_delay_writecycles += eeprom.usec_delay_step;
          }
          else if (eeprom.adapt_state < 0)
          {
            /* To High before (toggle dir) */
            eeprom.usec_delay_writecycles += eeprom.usec_delay_step;
            if (eeprom.usec_delay_step > 1)
            {
              eeprom.usec_delay_step /= 2;
              eeprom.usec_delay_step--;
            }
          }
        }

        eeprom.adapt_state = 1;
      }
      else
      {
        /* To High (or good) now */
        D(printk("<D=%i d=%i\n",
               eeprom.usec_delay_writecycles, eeprom.usec_delay_step));
        
        if (eeprom.adapt_state < 0)
        {
          /* To High before */
          if (eeprom.usec_delay_step > 1)
          {
            eeprom.usec_delay_step *= 2;
            eeprom.usec_delay_step--;
            
            if (eeprom.usec_delay_writecycles > eeprom.usec_delay_step)
            {
              eeprom.usec_delay_writecycles -= eeprom.usec_delay_step;
            }
          }
        }
        else if (eeprom.adapt_state > 0)
        {
          /* To Low before (toggle dir) */
          if (eeprom.usec_delay_writecycles > eeprom.usec_delay_step)
          {
            eeprom.usec_delay_writecycles -= eeprom.usec_delay_step;
          }
          if (eeprom.usec_delay_step > 1)
          {
            eeprom.usec_delay_step /= 2;
            eeprom.usec_delay_step--;
          }
          
          eeprom.adapt_state = -1;
        }

        if (eeprom.adapt_state > -100)
        {
          eeprom.adapt_state--;
        }
        else
        {
          /* Restart adaption */
          D(printk("#Restart\n"));
          eeprom.usec_delay_step++;
        }
      }
#endif /* EEPROM_ADAPTIVE_TIMING */
      /* write until we hit a page boundary or count */
      do
      {
        i2c_outbyte(buf[written]);        
        if(!i2c_getack())
        {
          restart=1;
          printk(KERN_INFO "%s: write error, retrying. %d\n", eeprom_name, i);
          i2c_stop();
          break;
        }
        written++;
        p++;        
      } while( written < count && ( p % eeprom.sequential_write_pagesize ));

      /* end write cycle */
      i2c_stop();
      i2c_delay(eeprom.usec_delay_writecycles);
    } /* while */
  } /* for  */

  eeprom.busy--;
  wake_up_interruptible(&eeprom.wait_q);
  if (written == 0 && file->f_pos >= eeprom.size){
    return -ENOSPC;
  }
  file->f_pos += written;
  return written;
}

/* Closes the device. */

static int eeprom_close(struct inode * inode, struct file * file)
{
  /* do nothing for now */
  return 0;
}

/* Sets the current address of the eeprom. */

static int eeprom_address(unsigned long addr)
{
  int i;
  unsigned char page, offset;

  page   = (unsigned char) (addr >> 8);
  offset = (unsigned char)  addr;

  for(i = 0; i < EEPROM_RETRIES; i++)
  {
    /* start a dummy write for addressing */
    i2c_start();

    if(eeprom.size == EEPROM_16KB)
    {
      i2c_outbyte( eeprom.select_cmd ); 
      i2c_getack();
      i2c_outbyte(page); 
    }
    else
    {
      i2c_outbyte( eeprom.select_cmd | (page << 1) ); 
    }
    if(!i2c_getack())
    {
      /* retry */
      i2c_stop();
      /* Must have a delay here.. 500 works, >50, 100->works 5th time*/
      i2c_delay(MAX_WRITEDELAY_US / EEPROM_RETRIES * i);
      /* The chip needs up to 10 ms from write stop to next start */
     
    }
    else
    {
      i2c_outbyte(offset);
      
      if(!i2c_getack())
      {
        /* retry */
        i2c_stop();
      }
      else
        break;
    }
  }    

  
  eeprom.retry_cnt_addr = i;
  D(printk("%i\n", eeprom.retry_cnt_addr));
  if(eeprom.retry_cnt_addr == EEPROM_RETRIES)
  {
    /* failed */
    return 0;
  }
  return 1;
}

/* Reads from current address. */

static int read_from_eeprom(char * buf, int count)
{
  int i, read=0;

  for(i = 0; i < EEPROM_RETRIES; i++)
  {    
    if(eeprom.size == EEPROM_16KB)
    {
      i2c_outbyte( eeprom.select_cmd | 1 );
    }

    if(i2c_getack())
    {
      break;
    }
  }
  
  if(i == EEPROM_RETRIES)
  {
    printk(KERN_INFO "%s: failed to read from eeprom\n", eeprom_name);
    i2c_stop();
    
    return -EFAULT;
  }

  while( (read < count))
  {    
    if (put_user(i2c_inbyte(), &buf[read++]))
    {
      i2c_stop();

      return -EFAULT;
    }

    /*
     *  make sure we don't ack last byte or you will get very strange
     *  results!
     */
    if(read < count)
    {
      i2c_sendack();
    }
  }

  /* stop the operation */
  i2c_stop();

  return read;
}

/* Disables write protection if applicable. */

#define DBP_SAVE(x)
#define ax_printf printk
static void eeprom_disable_write_protect(void)
{
  /* Disable write protect */
  if (eeprom.size == EEPROM_8KB)
  {
    /* Step 1 Set WEL = 1 (write 00000010 to address 1FFFh */
    i2c_start();
    i2c_outbyte(0xbe);
    if(!i2c_getack())
    {
      DBP_SAVE(ax_printf("Get ack returns false\n"));
    }
    i2c_outbyte(0xFF);
    if(!i2c_getack())
    {
      DBP_SAVE(ax_printf("Get ack returns false 2\n"));
    }
    i2c_outbyte(0x02);
    if(!i2c_getack())
    {
      DBP_SAVE(ax_printf("Get ack returns false 3\n"));
    }
    i2c_stop();

    i2c_delay(1000);

    /* Step 2 Set RWEL = 1 (write 00000110 to address 1FFFh */
    i2c_start();
    i2c_outbyte(0xbe);
    if(!i2c_getack())
    {
      DBP_SAVE(ax_printf("Get ack returns false 55\n"));
    }
    i2c_outbyte(0xFF);
    if(!i2c_getack())
    {
      DBP_SAVE(ax_printf("Get ack returns false 52\n"));
    }
    i2c_outbyte(0x06);
    if(!i2c_getack())
    {
      DBP_SAVE(ax_printf("Get ack returns false 53\n"));
    }
    i2c_stop();
    
    /* Step 3 Set BP1, BP0, and/or WPEN bits (write 00000110 to address 1FFFh */
    i2c_start();
    i2c_outbyte(0xbe);
    if(!i2c_getack())
    {
      DBP_SAVE(ax_printf("Get ack returns false 56\n"));
    }
    i2c_outbyte(0xFF);
    if(!i2c_getack())
    {
      DBP_SAVE(ax_printf("Get ack returns false 57\n"));
    }
    i2c_outbyte(0x06);
    if(!i2c_getack())
    {
      DBP_SAVE(ax_printf("Get ack returns false 58\n"));
    }
    i2c_stop();
    
    /* Write protect disabled */
  }
}

module_init(eeprom_init);