[fprint] Documentation for writing a new driver

[Igor Filatov]

Hi Mark,

There are no high-level docs, unfortunately. There's some valuable info in
comments in drv.c, sync.c, async.c, img.c etc. but it only covers specific
parts, not how they should interact.

There are 6 drivers for press-type sensors: aes3500.c, aes4000.c,
fdu2000.c, upektc.c, uru4000.c, vcom5s.c. But there isn't much difference
between press and swipe drivers. FP_SCAN_TYPE_* is used to determine which
messages to show ("please touch the sensor" vs. "please swipe..."), and I
think that's it. Besides that, all drivers essentially do the same thing:
obtain the fingerprint image and submit it. You can use any driver as a
reference.



On Fri, Mar 9, 2018 at 7:50 PM Mark Harfouche <mark.harfouche at gmail.com>
wrote:

> Hello all,
>
> I would like to develop a driver for the Validity 0091 sensor available on
> the Dell XPS13/15 9X60.
>
> I would say I have the driver reverse engineered to 95% (There might be a
> few things I still don’t understand from the internal state machine).
> https://github.com/hmaarrfk/Validity91
> WIP: https://github.com/freedesktop/libfprint
>
> I found the libfprint source, can compile it, and started creating my own
> driver.
>
> However, I am confused about the internal workings of libfprint and the
> functions I need to define.
> I tried to follow examples that were included, but it seemed that they
> were mostly “swipe”‘ sensors, and not capacitive style sensor.
> Is there any good documentation about the state machines I need to
> implement with regards to the functions
>
>     .open = dev_open,
>     .close = dev_close,
>     .activate = dev_activate,
>     .deactivate = dev_deactivate,
>     .change_state = dev_change_state,
>
> Thanks,
>
> Mark
> ​
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> fprint at lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/fprint
>
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