Re: [RFC] Creating an eeprom class

Greg KH
2013-01-22T00:14:51Z

On Mon, Jan 21, 2013 at 08:25:59AM +0100, Thomas De Schampheleire wrote:
> On Sun, Jan 20, 2013 at 11:39 PM, Greg KH <gregkh@linuxfoundation.org> wrote:
> > On Sun, Jan 20, 2013 at 07:08:28PM +0100, Thomas De Schampheleire wrote:
> >> [plaintext and fixed address of David Brownell]
> >
> > David passed away a year or so ago, so that's really not going to help :(
>
> So sorry to hear that, I was not aware...
>
> >
> >> Hi,
> >>
> >> Several of the eeprom drivers that live in drivers/misc/eeprom export
> >> a binary sysfs file 'eeprom'. If a userspace program or script wants
> >> to access this file, it needs to know the full path, for example:
> >>
> >> /sys/bus/spi/devices/spi32766.0/eeprom
> >>
> >> The problem with this approach is that it requires knowledge about the
> >> hardware configuration: is the eeprom on the SPI bus, the I2C bus, or
> >> maybe memory mapped?
> >>
> >> It would therefore be more interesting to have a bus-agnostic way to
> >> access this eeprom file, for example:
> >> /sys/class/eeprom/eeprom0/eeprom
> >>
> >> Maybe it'd be even better to use a more generic class name than
> >> 'eeprom', since there are several types of eeprom-like devices that
> >> you could export this way.
> >
> > Does all of the existing "eeprom" devices use the same userspace
> > interface? If so, yes, having a "class" would make sense.
>
> All but one do. That one (eeprom_93cx6.c) exports its read/write
> functions to other kernel code, and is used in several
> wireless/ethernet drivers.

Then it shouldn't be used here, right?

> >> Or should we rather hook the eeprom code into the mtd subsystem?
> >
> > Why mtd?
>
> Because an eeprom is a piece of memory. Maybe mtd is overkill in term
> of the operations supported, but from a high-level perspective an
> eeprom is a memory technology device, right?

Everything is a memory device in the end :)

Feel free to send patches, but I don't think this is really a big deal
that deserves this type of change at the moment. Feel free to prove me
wrong though.

greg k-h