Messages in this thread | | | Date | Fri, 11 Dec 2015 14:43:33 +0100 | From | Andrew Lunn <> | Subject | Re: [PATCH 2/6] nvmem: Add backwards compatibility support for older EEPROM drivers. |
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On Fri, Dec 11, 2015 at 02:03:25PM +0100, Wolfram Sang wrote: > On Tue, Dec 08, 2015 at 03:05:07PM +0100, Andrew Lunn wrote: > > Older drivers made an 'eeprom' file available in the /sys device > > directory. Have the NVMEM core provide this to retain backwards > > compatibility. > > > > Signed-off-by: Andrew Lunn <andrew@lunn.ch> > > --- > > drivers/nvmem/Kconfig | 7 ++++ > > drivers/nvmem/core.c | 75 +++++++++++++++++++++++++++++++++++++++--- > > include/linux/nvmem-provider.h | 10 ++++++ > > 3 files changed, 88 insertions(+), 4 deletions(-) > > > > diff --git a/drivers/nvmem/Kconfig b/drivers/nvmem/Kconfig > > index bc4ea585b42e..b4e79ba7d502 100644 > > --- a/drivers/nvmem/Kconfig > > +++ b/drivers/nvmem/Kconfig > > @@ -13,6 +13,13 @@ menuconfig NVMEM > > If unsure, say no. > > > > if NVMEM > > +config NVMEM_COMPAT > > + bool "Enable /sys compatibility with old eeprom drivers" > > + help > > + Older EEPROM drivers, such as AT24, AT25, provide access to > > + the eeprom via a file called "eeprom" in /sys under the > > + device node. Enabling this option makes the NVMEM core > > + provide this file to retain backwards compatibility > > I don't like this being a Kconfig option TBH. In most cases, when I read > "retain backwards compatibility" in Kconfig help texts, I keep the > option activated because I don't know the details when exactly it is > safe to disable it. Plus, we have too many Kconfig symbols already. > > I suggest to add this flag to nvmem_config and let the old eeprom > drivers always set this flag because they need to provide this file for > some more time, if not forever. New drivers using the nvmem_layer will > probably not want to set this.
I'm happy to do this, if the NVMEM core maintainers agree.
> BTW how does this NVMEM framework relate to the memory_accessor > framework. Can it be used to replace it? I think we should keep the > number of eeprom interfaces at a sane level, preferably 1 ;)
The memory_accessor framework only seems to work with old style platform data devices, where you can register the callback function to be used during probe. Because it cannot be used in a DT system, there are very few users of it, only boards in arch/arm/mach-davinci. They use it to get their MAC address out of the EEPROM. There are no users of the AT25 equivalent, which is why i removed it. So this API is dying on its own.
The NVMEM framework has a similar API for accessing the whole EEPROM, and a much finer grained API for accessing cells within the EEPROM, for example saying bytes 16-22 is the MAC address cell.
However, the NVMEM APIs are DT only, so are not a replacement for memory_accessor. We need to keep memory_accessor until Davinci gets converted to DT.
> Also adding Pantelis to CC who also submitted at24 NVMEM support a while > ago.
Thanks for pointing this out, i was not aware of that patch.
Thanks Andrew
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