On Thu, May 13, 2021 at 05:37:19PM +0200, Stephan Gerhold wrote:
> On Thu, May 13, 2021 at 07:48:55AM -0700, Mark Greer wrote:
> > On Thu, May 13, 2021 at 01:49:53PM +0200, Stephan Gerhold wrote:
> > > I have a couple of "recycled" smartphones running mainline Linux
> > > and some of them do have NFC chips. I have two with NXP PN547
> > > (supported by nxp,nxp-nci-i2c), one with Samsung S3FWRN5
> > > (samsung,s3fwrn5-i2c) and even one with Broadcom BCM2079x I think
> > > (this one does not have a driver for the Linux NFC subsystem sadly).
> > > 
> > > +Cc phone-devel@vger.kernel.org, in case other people there are
> > > interested in NFC :)
> > > 
> > > The NXP/Samsung ones seems to work just fine. However, since there are
> > > barely any userspace tools making use of Linux NFC all my testing so far
> > > was limited to polling for devices with "nfctool" and being happy enough
> > > when it realizes that I hold some NFC tag close to the device. :S
> > 
> > There is a user-level daemon that is the counterpart for the in-kernel
> > NFC subsystem.  It is called neard and is available here:
> > 
> > 	git://git.kernel.org/pub/scm/network/nfc/neard.git
> > 
> > There are a few test script in it that will let you read and write NFC
> > tags, and do some other things.  We can add some more tests to that set
> > as we go.
> > 
> 
> Yeah, I packaged that for Alpine Linux / postmarketOS.
> "nfctool" also comes from "neard" as far as I can tell :)
> 
> I think I also played with the Neard test scripts a bit at some point,
> and managed to read some NFC tag thing inside an old Yubikey NEO
> that I found, but didn't really know what else to do.

Yeah, there isn't a whole lot you can do but beyond reading/writing
tags and peer-to-peer, there are things like Bluetooth and Wifi
handover, Android Application Record support, and at least some
support for Secure Engine.

> > > I would be happy to do some more testing if someone has something useful
> > > that can be tested. However, I guess ideally we would have someone who
> > > actually uses Linux NFC actively for some real application. :)
> > 
> > Ideally, you should have some NFC tags of various types.  Types 2, 3,
> > 4A, 4B, and 5 tags are supported.  Peer-to-peer mode is supported too

I should have mentioned type 1 as well but I don't have the hardware
to test it.

> > so you should be able to transfer data from one of your phones to the
> > other over NFC (and do a BT hand-over, if you're interested).
> > 
> 
> I guess this is where I kind of lack hardware as well at the moment,
> I don't have any programmable NFC tags at the moment (although I guess
> those should be quite cheap). I might play with the peer-to-peer mode
> a bit when I find time.

Please let me/us know how it goes.

> > Note that the specified range for NFC is only 4 cm and poor antenna
> > design, etc. means that the actual range is usually much less (e.g.,
> > they amost have to touch).  Also note that there are timing constraints
> > so you may need to make the scheduling priority of the interrupt thread
> > of your NFC driver real-time.
> > 
> 
> Yeah I noticed, always need to search for a while to find the right spot
> on the phone. :)

Yeah, it can be an Easter egg hunt on many phones.  :)

Mark
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