linux-kernel - Re: [PATCH v4 0/4] Bluetooth/gnss: GNSS support for TiWi chips

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Date: Tue, 11 Jun 2024 10:32:56 +0200
From: Andreas Kemnade <andreas@...nade.info>
To: Adam Ford <aford173@...il.com>
Cc: Luiz Augusto von Dentz <luiz.dentz@...il.com>, marcel@...tmann.org,
 johan@...nel.org, pmenzel@...gen.mpg.de, jirislaby@...nel.org,
 gregkh@...uxfoundation.org, linux-kernel@...r.kernel.org,
 linux-bluetooth@...r.kernel.org, Tony Lindgren <tony@...mide.com>,
 tomi.valkeinen@...asonboard.com, Péter Ujfalusi
 <peter.ujfalusi@...il.com>, robh@...nel.org, hns@...delico.com
Subject: Re: [PATCH v4 0/4] Bluetooth/gnss: GNSS support for TiWi chips

Hi Adam,

On Mon, 10 Jun 2024 18:17:05 -0500
Adam Ford <aford173@...il.com> wrote:

> On Sat, Jun 8, 2024 at 2:20 PM Andreas Kemnade <andreas@...nade.info> wrote:
> >
> > Hi Adam,
> >
> > On Sat, 8 Jun 2024 14:00:38 -0500
> > Adam Ford <aford173@...il.com> wrote:
> >  
> > > On Thu, Jun 6, 2024 at 3:19 PM Andreas Kemnade <andreas@...nade.info> wrote:  
> > > >
> > > > Hi Luiz,
> > > >
> > > > On Thu, 6 Jun 2024 16:04:10 -0400
> > > > Luiz Augusto von Dentz <luiz.dentz@...il.com> wrote:
> > > >  
> > > > > Hi Andreas,
> > > > >
> > > > > On Thu, Jun 6, 2024 at 2:30 PM Andreas Kemnade <andreas@...nade.info> wrote:  
> > > > > >
> > > > > > Some of these chips have GNSS support. In some vendor kernels
> > > > > > a driver on top of misc/ti-st can be found providing a /dev/tigps
> > > > > > device which speaks the secretive Air Independent Interface (AI2) protocol.  
> > >
> > > I think you may have sent me a file to test, but I can't find the
> > > e-mail.   Can you tell me what tool you used to test it?  I can get
> > > gnss0 to enumerate, so I am close.
> > >  
> > hmm, /bin/cat is sufficient. It should spit out nmea now by default.
> >
> > For playing around with raw mode, you need the ai2raw parameter
> > and then you can play around with read-gps from
> > https://github.com/akemnade/bt200tools
> >  
> > > [   20.759857] hci-ti serial0-0: using DT
> > > '/ocp@...00000/serial@...6c000/bluetooth-gnss' for 'enable' GPIO
> > > lookup
> > > [   20.770263] of_get_named_gpiod_flags: parsed 'enable-gpios'
> > > property of node '/ocp@...00000/serial@...6c000/bluetooth-gnss[0]' -
> > > status (0)
> > > [   29.221588] gnss: GNSS driver registered with major 244
> > >  
> > That is nice.  
> 
> I think I am stuck.  The closed-sourced GPS binary that Logic PD did
> was done a 3rd party which has since been sold, and Logic PD never had
> the source code, I just get junk with this driver:
> 
Well, the whole thing is kept in secrecy. But the junk you get is just 
plain NMEA which I get also when device is indoors, so you got the chip
into a mode which common user space (like gpsd) understands. So IMHO that is a
Tested-By. So thanks a lot. I am happy with that result for the first step.

So first rpc was tested with a Motorola tablet and the BT200, this one now
with two different devices, so it is a good situation. 

> $GPGLL,,,,,,V,N*64
> $GPRMC,,V,,,,,,,,,,N*53
> $GPGGA,,,,,,0,,,,,,,,*66
> $GPVTG,,T,,M,,N,,K,N*2C
> $GPGSA,M,1,,,,,,,,,,,,,,,*12
> $GPGSV,1,1,00*79
> $GPGLL,,,,,,V,N*64
> $GPRMC,,V,,,,,,,,,,N*53
> $GPGGA,,,,,,0,,,,,,,,*66
> $GPVTG,,T,,M,,N,,K,N*2C
> $GPGSA,M,1,,,,,,,,,,,,,,,*12
> $GPGSV,1,1,00*79
> $GPGLL,,,,,,V,N*64
> $GPRMC,,V,,,,,,,,,,N*53
> $GPGGA,,,,,,0,,,,,,,,*66
> $GPVTG,,T,,M,,N,,K,N*2C
> $GPGSA,M,1,,,,,,,,,,,,,,,*12
> $GPGSV,1,1,00*79
> 
A note: contrary to other GPS I have seen, this one does not give
out satellite reception strength if not much is known about
position. So this pattern might continue a bit even if antenna
is there and gps reception is good. Much development of this
driver was done in a hammock with keyboard in a sleeping bag outside
so I know a bit...

> I am not 100% positive, but I think the antenna might be required to
> be powered.  I'll talk with the HW engineer who designed the Torpedo +
> Wireless SOM and see if he remembers anyhthing about the GPS.  I know
> for a fact that Logic PD doesn't have the source code for their GPS
> demo, and I know it doesn't work with modern kernels, so i can't
> compare the performance.
> 
Well, and demo tools are not easily available anywhere...
Well, I think if there is some special antenna powering stuff,
that can be done in a second step. Probably just a gpio or something.
But that would affect both the testing tools and the in-kernel
solution.

As said, you might use the ai2raw=1 parameter and try the read_gps from
bt200tools. Or the demo might work if you symlink gnss0 to tigps.

> :-(

Well, no, correct is :-)

Regards,
Andreas