Hi Matt, On Tue, 06 Nov 2007 18:53:11 +0000, Matt Sealey wrote: > Jean Delvare wrote: > > On Mon, 05 Nov 2007 21:52:06 +0000, Matt Sealey wrote: > >> Well, all i2c devices have a chip id you can probe for (...) > > > > This statement is completely incorrect. I2C devices do NOT have > > standard ID registers. Some devices have proprietary ID registers, some > > don't, it's really up to the manfacturer. > > All I2C slave devices have to have a 7- or 10-bit address to identify them > by. They *may* not report what they ARE, but this is 9 times out of > 10 a hardware design decision of soldering the chip to a board and > the address is then coded into device trees or hardcoded into drivers. > > Whoever designed the board and has the datasheets knows the address > they're supposed to be at, and the device can accept this. > > You simply cannot entertain an i2c bus with "anonymous and unnumbered > devices", every one has to have an address it responds to, however > it is defined, or it just does not work.
Of course, but it is all about addressing, NOT identifying. > WRT cell-index this is an index of the bus on the chip (not the logical > i2c bus but the physical difference between two i2c controllers) and > then any i2c devices which need to be communicated with would be > child nodes, their reg property reflecting their slave address, is > that not correct? I am not familiar with the OF tree, I can't tell, sorry. -- Jean Delvare _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@ozlabs.org https://ozlabs.org/mailman/listinfo/linuxppc-dev
