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 > 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. > > 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 >
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