Kernel driver w1_therm
  ====================
  
  Supported chips:
    * Maxim ds18*20 based temperature sensors.

    * Maxim ds1825 based temperature sensors.

  
  Author: Evgeniy Polyakov <johnpol@2ka.mipt.ru>
  
  
  Description
  -----------

  w1_therm provides basic temperature conversion for ds18*20 devices, and the
  ds28ea00 device.

  supported family codes:
  W1_THERM_DS18S20	0x10
  W1_THERM_DS1822		0x22
  W1_THERM_DS18B20	0x28

  W1_THERM_DS1825		0x3B

  W1_THERM_DS28EA00	0x42

  
  Support is provided through the sysfs w1_slave file.  Each open and
  read sequence will initiate a temperature conversion then provide two
  lines of ASCII output.  The first line contains the nine hex bytes
  read along with a calculated crc value and YES or NO if it matched.
  If the crc matched the returned values are retained.  The second line
  displays the retained values along with a temperature in millidegrees
  Centigrade after t=.
  
  Parasite powered devices are limited to one slave performing a
  temperature conversion at a time.  If none of the devices are parasite
  powered it would be possible to convert all the devices at the same
  time and then go back to read individual sensors.  That isn't
  currently supported.  The driver also doesn't support reduced

  precision (which would also reduce the conversion time) when reading values.
  
  Writing a value between 9 and 12 to the sysfs w1_slave file will change the
  precision of the sensor for the next readings. This value is in (volatile)
  SRAM, so it is reset when the sensor gets power-cycled.
  
  To store the current precision configuration into EEPROM, the value 0
  has to be written to the sysfs w1_slave file. Since the EEPROM has a limited
  amount of writes (>50k), this command should be used wisely.

  
  The module parameter strong_pullup can be set to 0 to disable the

  strong pullup, 1 to enable autodetection or 2 to force strong pullup.
  In case of autodetection, the driver will use the "READ POWER SUPPLY"
  command to check if there are pariste powered devices on the bus.
  If so, it will activate the master's strong pullup.
  In case the detection of parasite devices using this command fails
  (seems to be the case with some DS18S20) the strong pullup can
  be force-enabled.
  If the strong pullup is enabled, the master's strong pullup will be
  driven when the conversion is taking place, provided the master driver
  does support the strong pullup (or it falls back to a pullup

  resistor).  The DS18b20 temperature sensor specification lists a
  maximum current draw of 1.5mA and that a 5k pullup resistor is not
  sufficient.  The strong pullup is designed to provide the additional
  current required.

  
  The DS28EA00 provides an additional two pins for implementing a sequence
  detection algorithm.  This feature allows you to determine the physical
  location of the chip in the 1-wire bus without needing pre-existing
  knowledge of the bus ordering.  Support is provided through the sysfs
  w1_seq file.  The file will contain a single line with an integer value
  representing the device index in the bus starting at 0.