Re: [PATCH] RFC: fmc: Try to convert to GPIO descriptors

["Enrico Weigelt, metux IT consult" <lkml@xxxxxxxxx>]

On 11.06.19 16:58, Alessandro Rubini wrote:

Hi,

> This FMC (fpga mezzanine carrier) is a "slot" for peripheral boards.
> Like shields for beaglebone or such stuff.  So there is a board
> (and our own are actually pci-x and vme) with the FPGA, and the pins
> are carried to this "mezzanine" where the I/O happens. The mezzanine
> is usually just dumb, but it has the mandatory eeprom.

Ah, the fpga directly terminates w/ pcix or vme ?

Okay, now I'm begining to get a picture ...

So, from *logical* point of view (leaving aside the physical aspects),
we have either pcix or vme cards, carrying an eepromp and an fpga ?
The i2c and gpio controllers are also implemented in the fpga ?

> So, our "fine delay" board, that can timestamp pulses and generate
> other pulses at precise times) can plug in both the pcix and vme carrier.

Do the bitfiles differ between pcix and vme case ?

> The tow major ones, IIUC, are (1) the same mezzanine would require
> different bitstreams according to external information and (2) the
> fpga binary itself my expose different "devices" where a generalized
> driver would benefit, instead of a mezzanine-specific driver.

Have you already tried the MFD approach, where a board (in this case:
bitfile) specific driver instantiates several generic ones ?


--mtx

-- 
Enrico Weigelt, metux IT consult
Free software and Linux embedded engineering
info@xxxxxxxxx -- +49-151-27565287