On Fri, May 08, 2020 at 01:26:52PM +0300, Andy Shevchenko wrote: > 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). Nah, It's not a lot, barely a few things. What is useful is the registers map (though it has to be shifted and most of the registers are unused), IO operations (two small read-write methods with questionable design) and possibly a few lines of config setting procedure. You think I didn't had in mind to integrate this controller support into the generic driver or resuse something from there? If it was worth a try I would have done it. -Sergey > > -- > With Best Regards, > Andy Shevchenko
