On Mar 25 2003, at 09:20, Greg KH was caught saying: > On Tue, Mar 25, 2003 at 03:42:14PM +0100, Jan Dittmer wrote: > > This adds support for reading eeproms. > > Tested against latest bk changes with i2c-isa. > > I'd like to hold off in submitting the i2c chip drivers just yet, due to > the changes for sysfs that are going to be needed for these drivers. > > As an example of the changes necessary, here's a patch against the i2c > cvs version of the eeprom.c driver that converts it over to use sysfs, > instead of the /proc and sysctl interface. It's still a bit rough, but > you should get the idea of where I'm wanting to go with this. As you > can see, it takes about 100 lines of code off of this driver, which is > nice. > > I'm copying the sensors list too, as they wanted to see how this was > going to be done. > > Comments? I would like to suggest completely re-writing the user interface to the EEPROM device. As an applications programmer, I should not have to open a separate sysfs file for each 16 bytes in the EEPROM. I should be able to open a single file and perform read/write/llseek operations on the file descriptor. I don't think that the actual data of the EEPROM device is something that belongs in sysfs, just as the data on a hard drive or from a serial port is not read through their sysfs counterparts. Furthermore, I think that checksum data is not something that should be in the kernel, but in the application that is using it. An application can open() /dev/eepromX (/dev/nvramX maybe?) and read the data and ensure that the checksum is OK. Not all applications will have the same checksum mechanism, location, etc. >From my experience in seeing I2C eeproms on embedded systems, most people end up writing a custom little driver that does just what I said above: read/write/llseek. The eeprom driver should export the data for each eeprom through /dev/eeprom interfaces This also allows for someone to add a driver for larger EEPROMs (I have 512byte eeproms on some embedded boards) w/o having to add even more entries to sysfs for the remaining data. ~Deepak -- Deepak Saxena MontaVista Software - Powering the Embedded Revolution - www.mvista.com
