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

[Jagan Teki]

On Wed, Feb 28, 2018 at 3:12 PM, Prabhakar Kushwaha
<prabhakar.kushwaha at nxp.com> wrote:
> [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 at 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

These look going in reverse direction, since
drivers/mtd/spi-nor/fsl_qspi was meant for SPI-NOR flash(from initial
version SPI-NOR framework patches) and now it going in driver/spi..
look like it need more discussion with respective people who involved
on these.

>
>
> 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.

As of now, I would like to write it in driver/mtd/spi-nor assuming all
LUT or fsl related changes donesn't harm core areas so-that moving
back to drivers/spi might be easy if Linux does.

>
> 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

Pls use this https://github.com/openedev/u-boot-spi/commits/master