On Sun, Nov 26, 2023 at 1:47 PM Andreas Kemnade <andreas@xxxxxxxxxxxx> 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. > Implement something comparable as a GNSS interface. > > With some userspace tools a proof-of-concept can be shown. A position > can be successfully read out. Basic properties of the protocol are > understood. > > This was tested on the Epson Moverio BT-200. Can you tell me which WiLink chip this uses? I'd like to try it on the WL1283, but I want to understand which WiLink chips you're targeting. adam > > This is sent out as an early RFC to ensure I am going onto the right > track: > > So the main questions I see: > - is the approach right to abandon drivers/misc/ti-st? > > - Output at /dev/gnssX: > AI2 vs. NMEA > The chip can be configured into sending AI2-encapsulated NMEA, > or proving data in a binary format. > Some research has to be done yet for the details. > A pile of logs is waiting for further analysis... > > Arguments for/against NMEA: > + Userspace is prepared to handle it > + Power management can be easily done by the kernel > - Less functionality can be used. > > Arguments for/against AI2: > + Full functionality can be accessed from userspace (incl. A-GPS, > maybe raw satellite data) > - Userspace has to behave to have proper power management > - No freely (not even as in beer) tool available to fully use AI2, > so there will be only a real advantage after long "French Cafe" > sessions. > > More detailed tings: > - Some live cycle management is left out. Since it depends > on the decisions above, I have not put much thought into it. > - Should some pieces go into drivers/gnss? > - detection for GNSS availability: For now the node name is > used. But the device should be there if the chip supports it > and things are wired up properly. > > Andreas Kemnade (3): > gnss: Add AI2 protocol used by some TI combo chips. > bluetooth: ti-st: add GNSS support for TI Wilink chips > drivers: misc: ti-st: begin to deorbit > > drivers/bluetooth/hci_ll.c | 154 ++++++++++++++++++++++++++++++++++++- > drivers/gnss/core.c | 1 + > drivers/misc/ti-st/Kconfig | 2 +- > include/linux/gnss.h | 1 + > 4 files changed, 156 insertions(+), 2 deletions(-) > > -- > 2.39.2 > >
