linux-old/Documentation/i2c/ten-bit-addresses
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   1The I2C protocol knows about two kinds of device addresses: normal 7 bit 
   2addresses, and an extended set of 10 bit addresses. The sets of addresses
   3do not intersect: the 7 bit address 0x10 is not the same as the 10 bit
   4address 0x10 (though a single device could respond to both of them). You
   5select a 10 bit address by adding an extra byte after the address
   6byte:
   7  S Addr7 Rd/Wr ....  
   8becomes
   9  S 11110 Addr10 Rd/Wr
  10S is the start bit, Rd/Wr the read/write bit, and if you count the number
  11of bits, you will see the there are 8 after the S bit for 7 bit addresses,
  12and 16 after the S bit for 10 bit addresses.
  13
  14WARNING! The current 10 bit address support is EXPERIMENTAL. There are 
  15several places in the code that will cause SEVERE PROBLEMS with 10 bit
  16addresses, even though there is some basic handling and hooks. Also,
  17almost no supported adapter handles the 10 bit addresses correctly.
  18
  19As soon as a real 10 bit address device is spotted 'in the wild', we
  20can and will add proper support. Right now, 10 bit address devices
  21are defined by the I2C protocol, but we have never seen a single device
  22which supports them.
  23
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