Re: Linux gnss driver SPI support?

[Tim Harvey <tharvey@xxxxxxxxxxxxx>]

On Wed, Jan 6, 2021 at 3:21 AM Johan Hovold <johan@xxxxxxxxxx> wrote:
>
> On Tue, Jan 05, 2021 at 10:23:43AM -0800, Tim Harvey wrote:
> > Johan,
> >
> > I have noticed you maintain a gnss receiver subsystem and according to
> > the device-tree binding Documentation it looks like it supports SPI
> > but I'm not seeing any code support for SPI. Am I missing something or
> > would that support need to be added for use?
>
> Correct, there are currently no drivers supporting SPI and hence no
> shared implementation either like there is for UART interfaces.
>
> The driver for your device would need to handle the SPI bits itself for
> now. What kind of device is it?

Johan,

It is the u-blox ZOE-M8Q which has a UART as well as SPI/I2C/SQI
interface. The particular board design we are working on is
unfortunately out of UART's which is why we were looking at connecting
it via SPI.

I did come across a posting about this [1] which uses a userspace app
that creates a spy to pty bridge but it seems like they ran into some
performance/latency issues.

Tim
[1] https://portal.u-blox.com/s/question/0D52p00008jOh43CAC/using-neo-m8p-over-spi-as-a-high-accuracy-time-source-with-chrony