On 10-Dec-18 6:32 PM, Jagan Teki wrote: > On Thu, Dec 6, 2018 at 11:55 PM Vignesh R <[email protected]> wrote: >> >> Hi Jagan, >> >> On 06-Dec-18 10:44 PM, Jagan Teki wrote: >>> On Tue, Dec 4, 2018 at 5:56 PM Vignesh R <[email protected]> wrote: >>>> >>>> U-Boot SPI NOR support (sf layer) is quite outdated as it does not >>>> support 4 byte addressing opcodes, SFDP table parsing and different types >>>> of >>>> quad mode enable sequences. Many newer flashes no longer support BANK >>>> registers used by sf layer to a access >16MB space. >>>> Also, many SPI controllers have special MMIO interfaces which provide >>>> accelerated read/write access but require knowledge of flash parameters >>>> to make use of it. Recent spi-mem layer provides a way to support such >>>> flashes but sf layer isn't using that. >>>> This patch series syncs SPI NOR framework from Linux v4.19. It also adds >>>> spi-mem support on top. >>>> So, we gain 4byte addressing support and SFDP support. This makes >>>> migrating to U-Boot MTD framework easier. >>> >>> We(someone) has proposed this sync before, but we(at-least I) rely on >>> implementing via DM not direct sync to Linux. >> >> As I said in my cover letter, U-Boot sf layer is unable to support newer >> flashes mainly due to lack of 4 byte addressing and proper support for >> MMIO capable SPI controllers. >> My idea of fixing this is to borrow _features_ from Linux SPI NOR "as >> is". All that's needed is stateless 4 byte addressing, SFDP >> parsing(optionally), Quad/Octal support and spi-mem like abstraction for >> MMIO capable Controllers. I see no point in re-coding them from ground up. >> >> Could you be more specific on what you would like to see here in DM way? >> I have no issues in adapting this code to any framework here in U-Boot. >> Linux has driver model and SPI NOR subsystem is a framework and >> therefore any code ported from Linux will inherently have those >> abstractions. The only difference I see wrt your code in branch below vs >> this series is SPI-NOR uclass. This can be easily achieved by moving >> nor->ops out of struct spi_nor into uclass abstraction. >> Upstream Linux is anyways merging m25p80 and spi-nor so I did not see a >> need for SPI NOR uclass. I am okay to change that if you insist on >> having it. > > Merging or syncing spi-nor features stuff from Linux is good, I'm not > stopping that. but this can be do by satisfying u-boot driver-model > with proper architectural model. I know you take care but I'm not sure > ie what can be manageable for long term. > > Let's discuss the proper architectural model, so-that we can move > further to incorporate the changes accordingly. (thanks at last we > have a thread to discuss) > > Linux m25p80 is moved to spi-nor right? so does controllers on spi-nor > should be reside in same area like drivers/mtd/spi-nor or it should be > part of spi-mem. The last mail with Boris, noted all spi-nor can't be > fit into spi-mem(sorry I lost the thread) >
Yes, ATM all drivers fit into spi/spi-mem APIs and don't see any need for new spi-nor uclass > Example: we have zynq qspi it support BAR(with >16MB flashes), dual > qspi ect so does it comes under spi-mem or spi-nor? > In current mainline U-Boot, I see _no_ users of flags: SF_DUAL_STACKED_FLASH and SF_DUAL_PARALLEL_FLASH (I don't see flash->dual_flash set to any of the above enums). But if we do need to support such flashes in future, current address translation logic can be added to spi-nor.c (based on a DT flag), along with a way to pass this info via spi-mem ops. I would suggest to look at spi-mem ops (and in Linux mainline as well), if there are any shortcomings we can discuss here. > So, if no driver should be part of spi-nor and all can be handle > spi-mem even-though they have controller specific features, yes we can > skip SPI_NOR_UCLASS otherwise we need spi-nor uclass that can be child > uclass of MTD. > In fact, after this series is merged, UCLASS_SPI_FLASH can be dropped and we can move to spi-nor(and sf_dataflash.c) directly under UCLASS_MTD. But, mostly likely would need to provide a lightweight MTD for SPL (similar to spi-nor-tiny.c) before that can be done. Regards Vignesh _______________________________________________ U-Boot mailing list [email protected] https://lists.denx.de/listinfo/u-boot
