text: /*
   * Linux driver for digital TV devices equipped with B2C2 FlexcopII(b)/III
   * flexcop-eeprom.c - eeprom access methods (currently only MAC address reading)
   * see flexcop.c for copyright information
   */
  #include "flexcop.h"
  
  
  static u8 calc_lrc(u8 *buf, int len)
  {
  	int i;
  	u8 sum = 0;
  	for (i = 0; i < len; i++)
  		sum = sum ^ buf[i];
  	return sum;
  }
  
  static int flexcop_eeprom_request(struct flexcop_device *fc,
  	flexcop_access_op_t op, u16 addr, u8 *buf, u16 len, int retries)
  {
  	int i,ret = 0;
  	u8 chipaddr =  0x50 | ((addr >> 8) & 3);
  	for (i = 0; i < retries; i++) {
  		ret = fc->i2c_request(&fc->fc_i2c_adap[1], op, chipaddr,
  			addr & 0xff, buf, len);
  		if (ret == 0)
  			break;
  	}
  	return ret;
  }
  
  static int flexcop_eeprom_lrc_read(struct flexcop_device *fc, u16 addr,
  		u8 *buf, u16 len, int retries)
  {
  	int ret = flexcop_eeprom_request(fc, FC_READ, addr, buf, len, retries);
  	if (ret == 0)
  		if (calc_lrc(buf, len - 1) != buf[len - 1])
  			ret = -EINVAL;
  	return ret;
  }
  
  /* JJ's comment about extended == 1: it is not presently used anywhere but was
   * added to the low-level functions for possible support of EUI64 */
  int flexcop_eeprom_check_mac_addr(struct flexcop_device *fc, int extended)
  {
  	u8 buf[8];
  	int ret = 0;
  
  	if ((ret = flexcop_eeprom_lrc_read(fc,0x3f8,buf,8,4)) == 0) {
  		if (extended != 0) {
  			err("TODO: extended (EUI64) MAC addresses aren't "
  				"completely supported yet");
  			ret = -EINVAL;
  		} else
  			memcpy(fc->dvb_adapter.proposed_mac,buf,6);
  	}
  	return ret;
  }
  EXPORT_SYMBOL(flexcop_eeprom_check_mac_addr);
  