On 6/5/24 18:40, Conor Dooley wrote: > On Tue, Jun 04, 2024 at 07:42:16PM +0200, Michael Walle wrote: >> On Tue Jun 4, 2024 at 7:01 PM CEST, Conor Dooley wrote: >>> On Tue, Jun 04, 2024 at 09:42:31AM +0200, Michael Walle wrote: >>>> These devices are more like an AT25 compatible EEPROM instead of >>>> flashes. Like an EEPROM the user doesn't need to explicitly erase the >>>> memory, nor are there sectors or pages. Thus, instead of the SPI-NOR >>>> (flash) driver, one should instead use the at25 EEPROM driver. >>>> >>>> Signed-off-by: Michael Walle <mwalle@xxxxxxxxxx> >>>> Cc: Uwe Kleine-König <u.kleine-koenig@xxxxxxxxxxxxxx> >>>> Cc: Thorsten Scherer <t.scherer@xxxxxxxxxxxx> >>>> Cc: Marek Vasut <marex@xxxxxxx> >>>> Cc: Imre Kaloz <kaloz@xxxxxxxxxxx> >>>> Cc: Andrew Lunn <andrew@xxxxxxx> >>>> Cc: Flavio Suligoi <f.suligoi@xxxxxxx> >>>> --- >>>> The referenced binding only supports the true AT25 compatible EEPROMs >>>> where you have to specify additional properties like size and page size >>>> or cypress FRAM devices where all the properties are discovered by the >>>> driver. I don't have the actual hardware, therefore I can't work on a >>>> proper driver and binding. But I really want to deprecate the use of >>>> these EEPROM like devices in SPI-NOR. So as a first step, mark the >>>> devices in the DT bindings as deprecated. >>>> >>>> There are three in-tree users of this. I hope I've CCed all the relevant >>>> people. With the switch to the at25 driver also comes a user-space >>>> facing change: there is no more MTD device. Instead there is an "eeprom" >>>> file in /sys now, just like for every other EEPROM. >>>> >>>> Marek already expressed, that the sps1 dts can likely be removed >>>> altogether. I'd like to hear from the other board DTS maintainers if >>>> they seem some problems moving to the EEPROM interface - or maybe that >>>> device isn't used at all anyway. So in the end, we can hopefully move >>>> all the users over to the at25 driver. >>>> --- >>>> Documentation/devicetree/bindings/mtd/jedec,spi-nor.yaml | 9 ++++++++- >>>> 1 file changed, 8 insertions(+), 1 deletion(-) >>>> >>>> diff --git a/Documentation/devicetree/bindings/mtd/jedec,spi-nor.yaml b/Documentation/devicetree/bindings/mtd/jedec,spi-nor.yaml >>>> index 6e3afb42926e..2dccb6b049ea 100644 >>>> --- a/Documentation/devicetree/bindings/mtd/jedec,spi-nor.yaml >>>> +++ b/Documentation/devicetree/bindings/mtd/jedec,spi-nor.yaml >>>> @@ -21,7 +21,6 @@ properties: >>>> (m25p(40|80|16|32|64|128)|\ >>>> n25q(32b|064|128a11|128a13|256a|512a|164k)))|\ >>>> atmel,at25df(321a|641|081a)|\ >>>> - everspin,mr25h(10|40|128|256)|\ >>>> (mxicy|macronix),mx25l(4005a|1606e|6405d|8005|12805d|25635e)|\ >>>> (mxicy|macronix),mx25u(4033|4035)|\ >>>> (spansion,)?s25fl(128s|256s1|512s|008k|064k|164k)|\ >>>> @@ -42,6 +41,14 @@ properties: >>>> - spansion,s25fs512s >>>> - const: jedec,spi-nor >>>> - const: jedec,spi-nor >>>> + >>>> + # Deprecated bindings >>>> + - items: >>>> + - pattern: "^everspin,mr25h(10|40|128|256)$" >>>> + - const: jedec,spi-nor >>>> + description: >>>> + Deprecated binding, use Documentation/devicetree/bindings/eeprom/at25.yaml. >>>> + deprecated: true >>> >>> The idea here seems okay, but directing people to use the at25 binding, >>> without actually documenting the replacement compatibles etc is far from >>> ideal. I think even a wording change that points out that that these >>> devices need to be documented in that file would be an improvement, the >>> current wording makes it seem like the works been done. >>> Until there's a replacement driver, I don't think you could really >>> expect anyone to move to a new binding anyway. >> >> Fair enough. The driver is already there and it basically works - >> Flavio is already using it. It is just, that at the moment you have >> to use the (deprecated) "atmel,at25" compatible and you'll have to >> specify pagesize etc. That is really hacky, because F/MRAM devices >> doesn't have a pagesize. >> >> Anyway, I was already working on the at25 binding but then I've >> noticed that the current FRAM binding is really hardcoded to cypress >> devices and as mentioned in the commit message, I don't have any Takahiro from cc may help with the cypress FRAM testing. >> hardware to actually write the proper driver support. Maybe we >> should settle on the binding first, i.e. >> >> compatible = "everspin,mr25", "atmel,at25"; >> size = <N>; >> >> vs >> >> compatible = "everspin,mr25h256"; # no size needed > > I dunno, I am usually biased to having the more specific compatible > and not needing the extra properties. I agree with the more specific compatible idea, but we shall aim that the specific compatible to be generic: "spi-fram" and maybe "spi-mram". Can it be done? > >> >> For reference, the already supported cypress fram has the following: >> >> compatible = "cypress,fm25", "atmel,at25"; >> # no size needed, because the driver will figure it out by reading >> # the ID >> >> Besides that, I would really get some feedback from the three >> in-tree users on migrating to the EEPROM driver and thus away from >> MTD. >> >> -michael >>
