Re: [PATCH 2/2] spi: Add Baikal-T1 System Boot SPI Controller driver

[Andy Shevchenko]

On Fri, May 8, 2020 at 1:15 PM Serge Semin
<Sergey.Semin@xxxxxxxxxxxxxxxxxxxx> wrote:
>
> On Fri, May 08, 2020 at 01:03:11PM +0300, Andy Shevchenko wrote:
> > On Fri, May 8, 2020 at 12:37 PM Serge Semin
> > <Sergey.Semin@xxxxxxxxxxxxxxxxxxxx> wrote:
> > >
> > > This SPI-controller is a part of the Baikal-T1 System Controller and
> > > is based on the DW APB SSI IP-core, but with very limited resources:
> > > no IRQ, no DMA, only a single native chip-select and just 8 bytes Tx/Rx
> > > FIFO available. In order to provide a transparent initial boot code
> > > execution this controller is also utilized by an vendor-specific block,
> > > which provides an CS0 SPI flash direct mapping interface. Since both
> > > direct mapping and SPI controller normal utilization are mutual exclusive
> > > only a one of these interfaces can be used to access an external SPI
> > > slave device. Taking into account the peculiarities of the controller
> > > registers and physically mapped SPI flash access, very limited resources
> > > and seeing the normal usecase of the controller is to access an external
> > > SPI-nor flash, we decided to create a dedicated SPI driver for it.
> >
> > It seems a lot of code.
> > Why can't you use spi-dw-mmio.c et al.?
>
> I said above why. Even though the registers set is similar It's too specific
> to be integrated into the generic DW SSI driver.

At least you may do at the beginning is to reuse header spi-dw.h and
put your stuff under
spi-dw-baikal.c or so. Then, look at the spi-dw.c and check what can
be reused (I think a lot).

-- 
With Best Regards,
Andy Shevchenko