Re: [PATCH v2 5/6] tpm: add driver for cr50 on SPI

[Alexander Steffen]

On 17.07.2019 23:38, Stephen Boyd wrote:
> Quoting Stephen Boyd (2019-07-17 12:57:34)
> > Quoting Alexander Steffen (2019-07-17 05:00:06)
> > > Can't the code be shared more explicitly, e.g. by cr50_spi wrapping
> > > tpm_tis_spi, so that it can intercept the calls, execute the additional
> > > actions (like waking up the device), but then let tpm_tis_spi do the
> > > common work?
> >
> > I suppose the read{16,32} and write32 functions could be reused. I'm not
> > sure how great it will be if we combine these two drivers, but I can
> > give it a try today and see how it looks.
>
> Here's the patch. I haven't tested it besides compile testing.

Thanks for providing this. Makes it much easier to see what the actual 
differences between the devices are.

Do we have a general policy on how to support devices that are very 
similar but need special handling in some places? Not duplicating the 
whole driver just to change a few things definitely seems like an 
improvement (and has already been done in the past, as with 
TPM_TIS_ITPM_WORKAROUND). But should all the code just be added to 
tpm_tis_spi.c? Or is there some way to keep a clearer separation, 
especially when (in the future) we have multiple devices that all have 
their own set of deviations from the spec?

Alexander