[U-Boot] [PATCH v10 03/27] mtd: add SPI-NOR core support

Prabhakar Kushwaha
2018-02-28T09:42:11Z

[Resending on correct patch of the patch-set]

Dear Jagan,

> -----Original Message-----
> From: U-Boot [mailto:u-boot-bounces at lists.denx.de] On Behalf Of Jagan
> Teki
> Sent: Thursday, December 28, 2017 11:42 AM
> To: u-boot at lists.denx.de
> Cc: Tom Rini <trini@konsulko.com>
> Subject: [U-Boot] [PATCH v10 03/27] mtd: add SPI-NOR core support
>
> Some of the SPI device drivers at drivers/spi not a real spi controllers, Unlike
> normal/generic SPI controllers they operates only with SPI-NOR flash
> devices. these were technically termed as SPI-NOR controllers, Ex:
> drivers/spi/fsl_qspi.c
>
> The problem with these were resides at drivers/spi is entire SPI layer
> becomes SPI-NOR flash oriented which is absolutely a wrong indication
> where SPI layer getting effected more with flash operations - So this SPI-NOR
> core will resolve this issue by separating all SPI-NOR flash operations from spi
> layer and creats a generic layer called SPI-NOR core which can be used to
> interact SPI-NOR to SPI driver interface layer and the SPI-NOR controller
> driver. The idea is taken from Linux spi-nor framework.
>
> =======================================
> cmd/spinor.c
> =======================================
> mtd-uclass.c
> =======================================
> spi-nor-uclass.c
> =======================================
> spi-nor.c
> =======================================
> m25p80.c zynq_qspinor.c
> =======================================
> spi-uclass.c
> =======================================
> zynq_qspi.c
> =======================================
> #####SPI NOR chip######
> =======================================
>

As per this patch-set, fsl_qspi is looks to be getting proposed in driver/mtd/spi-nor/ folder.

fsl_qspi is supporting both flash and fpga. We are not sure about its location.

There is an on-going effort for similar type of requirement in Linux by Boris Brezillon . It is dealing with controllers supporting NORs, NANDs, SRAMs etc.
http://patchwork.ozlabs.org/project/linux-mtd/list/?series=27088

Borris has also ported fsl_qspi in driver/spi to use this new framework. It is still not completely tested.
https://github.com/bbrezillon/linux/commit/43cc45764b975bfbb191de3f6a37e073da1a2706

Will you also follow similar approach as being done in http://patchwork.ozlabs.org/project/linux-mtd/list/?series=27088 for longer term?

For Now, We are planning to update fsl_qspi driver to support dynamic LUT. Similar patch is in progress in Linux http://patchwork.ozlabs.org/project/linux-mtd/list/?series=26084
Now we are confused, should be port fsl_qspi in driver/mtd/spi-nor and then update driver Or We update driver/spi/fsl_qspi for dynamic LUTs. We may need to modify existing framework to get all required info for dynamic LUT.

Also we want some change in framework like support of
- 4 byte address and SFDP : http://patchwork.ozlabs.org/project/uboot/list/?series=19621&state=*
- SMPT : in discussion in Linux http://patchwork.ozlabs.org/patch/869718/
Which code base should we use? u-boot-spi.git branch mtd-spinor-working or u-boot.git master branch

--pk