From mboxrd@z Thu Jan 1 00:00:00 1970 From: Maxime Ripard Subject: Re: MTD EEPROM support and driver integration Date: Thu, 11 Jul 2013 19:05:06 +0200 Message-ID: <20130711170506.GZ11243@lukather> References: <20130705201118.GM2959@lukather> <5811519.oHVuMujf0I@wuerfel> <20130706120112.GA11069@lukather> <8997501.Dchyii8uWX@wuerfel> <20130708083426.GO27646@sirena.org.uk> <20130708202538.GK11243@lukather> <20130709145510.GZ27646@sirena.org.uk> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="hEarWVD7htqb1VxP" Return-path: Content-Disposition: inline In-Reply-To: <20130709145510.GZ27646-GFdadSzt00ze9xe1eoZjHA@public.gmane.org> Sender: linux-i2c-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Mark Brown Cc: Arnd Bergmann , Greg Kroah-Hartman , David Woodhouse , Artem Bityutskiy , Shawn Guo , linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, oliver-dxLnbx3+1qmEVqv0pETR8A@public.gmane.org, linux-mtd-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, Wolfram Sang , Jean Delvare , linux-i2c-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: linux-i2c@vger.kernel.org --hEarWVD7htqb1VxP Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable Hi Mark, On Tue, Jul 09, 2013 at 03:55:10PM +0100, Mark Brown wrote: > On Mon, Jul 08, 2013 at 10:25:38PM +0200, Maxime Ripard wrote: > > On Mon, Jul 08, 2013 at 09:34:26AM +0100, Mark Brown wrote: >=20 > > > I'd really like to see more discussion of this "DT parsing code for > > > regmap" idea... I've missed almost all the context here. >=20 > > The context was that I found we lack a way to simply express the need > > for one driver to get a value from an EEPROM-like device, for example to > > get a MAC Address, or a serial number, in a generic way, without having > > to poke directly with some custom function that would be exported by the > > EEPROM driver. >=20 > This sort of information is often stored in places like flash partitions > too. Are we sure that regmap is a good place to be hooking in here? > The use case is sane, and being able to use regmap to do some of it > seems sensible (I've seen people use OTP in PMICs for similar purposes) > but perhaps an additional layer of abstraction on top makes sense. Ah, I didn't thought it could be stored into a partition. Ok, so using an intermediate abstraction for this makes sense (probably using regmap for all the accesses that are relevant, like i2c, spi or mmio) > > What we've been discussing so far is that: > > - To have a common framework we could base our work on, we could move > > the EEPROM drivers from drivers/misc/eeprom to MTD > > - To declare the ranges that needed to be used by a driver that was > > needing a value from one of those MTD drivers, we would use regmap > > with a MTD backend > > - And since we actually need to declare which ranges and in which > > device one driver would have to retrieve this value from, we were > > actually in need of DT bindings. >=20 > > This is pretty much the only context involved, and we are at the early > > stage of the discussion, so any comment is very welcome :) >=20 > If this stuff is being represented in MTD doesn't MTD already have > adequate abstractions for saying "this region in flash". But otherwise > this seems fine, it's not a generic regmap DT binding but instead rather > more specific than that. Yes, since we seem to be going to a point where regmap will be a convenience in this case, we probably won't need a generic regmap binding, but rather a generic way to define a range and offset into a referenced device. Arnd, the others, is this ok for you? Maxime --=20 Maxime Ripard, Free Electrons Embedded Linux, Kernel and Android engineering http://free-electrons.com --hEarWVD7htqb1VxP Content-Type: application/pgp-signature; name="signature.asc" Content-Description: Digital signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.12 (GNU/Linux) iQIcBAEBAgAGBQJR3uXCAAoJEBx+YmzsjxAgMugP/28QkZ0Yz7D+Xrk8UsJFiLh9 jam5T1KOqga2lKB2N4uAnyQiWtuaZMX/ywELmxO7esx2055efI91r8oUj7PO0qJu vgW/0d1zDTmRLZ/KdaDj/xvpkiotx6dSQghMXFdAiscIZJEF3XccLg+D8rQd5Vig hagL31ateq28hM6GHeb6xE9HSX1uZRPFPrapWjwTAuWpYKNgt5TaEUpO9VIGk5LA GEHJJL+wijJoeEF0/9w6Ub06BlUpjt6b86H591oyOQqnhLmABgi7CMPH4qtfrCDS RAYahsSgkcKoVYCOD9YjULIgPS7Lh5EjbYoczkn9VDehN8YdSt0Jkhi5Z84ottuX 6YTbDwtf0o4ijOGbI4My97QuLJ19tYWL0/ACx/yrVYIn+7WEFSxrEsIYgbFthIdn GyYjVmUixNFsB6JokjfmWDyak3LfvMfaH4PCZSuFrS+7u2XyEKQoc1hQBaDSCSTa 8e9jCuvCrB0UaLmasTwflsD/HChv/m8Q4q5uJp0s3ASsg5II+T5eujqdl7EEKcBS fklMfHOhBLZ2HoXTRQenaNi/roVLtYqr2j55NHTwjFeZvZbRgMPi9VTPEZzKGM6N JFenmvWnrjS0iNuwdn8oqmlg8FHNZmeBaTaZEKholDUkqZTrRS0GujJ5H0wfArrh +U6CLMYZX1u3W26egsRW =rUP+ -----END PGP SIGNATURE----- --hEarWVD7htqb1VxP--