Re: [PATCH] Add spi-nor driver for Realtek RTL838x/RTL839x switch SoCs

[Bert Vermeulen]

On 12/20/20 9:51 AM, Chuanhong Guo wrote:
> Hi!
>
> On Sun, Dec 20, 2020 at 7:01 AM Bert Vermeulen <bert@xxxxxxxx> wrote:
> > On 12/16/20 9:30 AM, Tudor.Ambarus@xxxxxxxxxxxxx wrote:
> > > On 12/15/20 11:46 PM, Bert Vermeulen wrote:
> > >> This driver supports the spiflash core in all RTL838x/RTL839x SoCs,
> > >> and likely some older models as well (RTL8196C).
> > >>
> > > Can we use SPIMEM and move this under drivers/spi/ instead?
> >
> > I wasn't aware spimem was the thing to use for new drivers. I will rewrite
> > the driver to that API.
>
> Are there any limitations preventing this from being implemented as a
> generic SPI controller?
> spi-nor and spi-mem are designed for controllers which can only perform
> spi-mem/spi-nor specific transfers. I can't find such limitations from
> your current driver code.
>
> BTW I found a SPI controller driver for RTL8196C here: [0]
> It seems pretty similar to the controller you are working on.
>
> [0]: 
https://github.com/hackpascal/lede-rtl8196c/blob/realtek/target/linux/realtek/files/drivers/spi/spi-realtek.c

The SoC's SPI core is very much intended for SPI flash use only, and indeed 
we haven't come across anything else connected to that SPI bus in dozens of 
devices.

I wrote my driver based on Realtek code and a datasheet for the (older) 
RTL8196C found floating around the net, and found no inconsistencies.

I hadn't seen that RTL8196C driver, but if it works that proves a plain SPI 
driver will do. I'll investigate.


--
Bert Vermeulen
bert@xxxxxxxx