On 07/12/18 3:21 PM, Boris Brezillon wrote:
On Thu, 6 Dec 2018 23:55:30 +0530 Vignesh R vigneshr@ti.com wrote:
On 06-Dec-18 10:44 PM, Jagan Teki wrote:
On Tue, Dec 4, 2018 at 5:56 PM Vignesh R vigneshr@ti.com 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U-Boot SPI NOR support (sf layer) is quite outdated as it does not support 4 byte addressing opcodes, SFDP table parsing and different types of quad mode enable sequences.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.
No, please don't add a SPI_NOR_UCLASS. We already have the MTD_UCLASS which is barely used by drivers, so if anything, we should work on converting drivers to this UCLASS and maybe automate a few more things for MTD drivers (like MTD dev registration/deregistration [1]) instead of adding yet another UCLASS.
I agree.
If you need an example of how integration with the DM (and the MTD UCLASS) should be been done, you can look at the SPI NAND driver [2].
[1]http://code.bulix.org/9lart9-519406 [2]http://git.denx.de/?p=u-boot.git;a=blob;f=drivers/mtd/nand/spi/core.c;h=cb8f...
Yeah, that can be done once MTD Kconfig cleanup is done and we have dropped UCLASS_SPI_FLASH (would also require sf_dataflash.c to be moved to MTD)