From mboxrd@z Thu Jan 1 00:00:00 1970 From: s.hauer@pengutronix.de (Sascha Hauer) Date: Mon, 23 Feb 2015 10:15:59 +0100 Subject: [RFC PATCH 1/3] eeprom: Add a simple EEPROM framework In-Reply-To: References: <1424365639-26634-1-git-send-email-srinivas.kandagatla@linaro.org> <1424365708-26681-1-git-send-email-srinivas.kandagatla@linaro.org> <54E78A31.9020306@linaro.org> Message-ID: <20150223091559.GA28214@pengutronix.de> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Fri, Feb 20, 2015 at 04:01:55PM -0600, Rob Herring wrote: > On Fri, Feb 20, 2015 at 1:25 PM, Srinivas Kandagatla > wrote: > > > > > > On 20/02/15 17:21, Rob Herring wrote: > >> > >> On Thu, Feb 19, 2015 at 11:08 AM, Srinivas Kandagatla > >> wrote: > >>> > >>> From: Maxime Ripard > >>> > >>> Up until now, EEPROM drivers were stored in drivers/misc, where they all > >>> had to > >>> duplicate pretty much the same code to register a sysfs file, allow > >>> in-kernel > >>> users to access the content of the devices they were driving, etc. > >>> > >>> This was also a problem as far as other in-kernel users were involved, > >>> since > >>> the solutions used were pretty much different from on driver to another, > >>> there > >>> was a rather big abstraction leak. > >>> > >>> This introduction of this framework aims at solving this. It also > >>> introduces DT > >>> representation for consumer devices to go get the data they require (MAC > >>> Addresses, SoC/Revision ID, part numbers, and so on) from the EEPROMs. > >>> > >>> Having regmap interface to this framework would give much better > >>> abstraction for eeproms on different buses. > >>> > >>> Signed-off-by: Maxime Ripard > >>> [srinivas.kandagatla: Moved to regmap based and cleanedup apis] > >>> Signed-off-by: Srinivas Kandagatla > >>> --- > >>> .../devicetree/bindings/eeprom/eeprom.txt | 48 ++++ > >>> drivers/Kconfig | 2 + > >>> drivers/Makefile | 1 + > >>> drivers/eeprom/Kconfig | 19 ++ > >>> drivers/eeprom/Makefile | 9 + > >>> drivers/eeprom/core.c | 290 > >>> +++++++++++++++++++++ > >>> include/linux/eeprom-consumer.h | 73 ++++++ > >>> include/linux/eeprom-provider.h | 51 ++++ > >> > >> > >> Who is going to be the maintainer for this? > > > > > > Am happy to be one. > > So please add a MAINTAINERS entry. > > [...] > > >>> += Data consumers = > >>> + > >>> +Required properties: > >>> + > >>> +eeproms: List of phandle and data cell specifier triplet, one triplet > >>> + for each data cell the device might be interested in. The > >>> + triplet consists of the phandle to the eeprom provider, then > >>> + the offset in byte within that storage device, and the length > >>> + in byte of the data we care about. > >> > >> > >> The problem with this is it assumes you know who the consumer is and > >> that it is a DT node. For example, how would you describe a serial > >> number? > > > > Correct me if I miss understood. > > Is serial number any different? > > Am hoping that the eeprom consumer would be aware of offset and size of > > serial number in the eeprom > > > > Cant the consumer do: > > > > eeprom-consumer { > > eeproms = <&at24 0 4>; > > eeprom-names = "device-serial-number"; > > Yes, but who is "eeprom-consumer"? DT nodes generally describe a h/w > block, but it this case, the consumer depends on the OS, not the h/w. > I'm not saying you can't describe where things are, but I don't think > you should imply who is the consumer and doing so is unnecessarily > complicated. > > Also, the layout of EEPROM is likely very much platform specific. Some > could have a more complex structure perhaps with key ids and linked > list structure. > > I would do something more simple that is just a list of keys and their > location like this: > > device-serial-number = ; > key1 = ; > key2 = ; Maybe better a node instead of a property. That would allow to use the standard reg property to describe the position in the eeprom. Also it would give consumers in dt a possibility to use a phandle to point to a variable: serial_number: var at c { reg = <0xc 0x8>; name = ; }; Sascha -- Pengutronix e.K. | | Industrial Linux Solutions | http://www.pengutronix.de/ | Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |