Am 03.07.2018 um 17:31 schrieb Mark Brown:

On Tue, Jul 03, 2018 at 05:09:38PM +0200, Andreas F?rber wrote:

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Am 03.07.2018 um 16:50 schrieb Mark Brown:

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A register map would work just as well here, we already have plenty of
devices that abstract at this level (most obviously the I2C/SPI devices
that use it to offer both interfaces with a single core driver).

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The address and data registers together form a two-byte SPI message!

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It is transmitted by writing to the CS register.

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The received data is afterwards available in another register.

Right, but it seems from the code that the hardware understands that
it's formatting register I/O and not just shifting in and out a byte
stream which is what a SPI controller does.  I'd not be surprised to
learn that the register you're calling a chip select register is a
strobe that initiates the transfer (and that this may be some of the
difficulty you're having with handling it in the way the framework
expects), the pattern with writing 1 followed immediately by 0 is a bit
of a flag here.

Yeah, the current implementation assumes exactly that. :)

I've seen such before hardware where I know it was intentionally
designed that way so it wouldn't be totally surprising.

If we don't implement a spi_controller here, then IIUC we can't have
multiple spi_device implementations for the devices on the receiving
end, as they rely on a spi_controller for their APIs.

Do you have an alternative solution for abstraction? A regmap would seem
to require putting everything into a monolithic SX1301 driver despite
those connected chipsets actually being regular, external SPI chips that
could also be attached to non-SX1301 SPI masters.

Regards,
Andreas

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