On Wed, May 2, 2018 at 3:16 AM, Johan Hovold <johan@xxxxxxxxxx> wrote: > On Tue, May 01, 2018 at 09:05:42AM -0500, Rob Herring wrote: >> On Thu, Apr 26, 2018 at 4:10 AM, Johan Hovold <johan@xxxxxxxxxx> wrote: >> > On Wed, Apr 25, 2018 at 01:16:58PM -0500, Rob Herring wrote: >> >> On Tue, Apr 24, 2018 at 11:34 AM, Johan Hovold <johan@xxxxxxxxxx> wrote: >> >> > Add binding for u-blox GNSS receivers. >> >> > >> >> > Note that the u-blox product names encodes form factor (e.g. "neo"), >> >> > chipset (e.g. "8") and variant (e.g. "q"), but that only formfactor and >> >> > chipset is used for the compatible strings (for now). >> >> > >> >> > Signed-off-by: Johan Hovold <johan@xxxxxxxxxx> >> >> > --- >> >> > .../devicetree/bindings/gnss/u-blox.txt | 31 +++++++++++++++++++ >> >> > .../devicetree/bindings/vendor-prefixes.txt | 1 + >> >> > 2 files changed, 32 insertions(+) >> >> > create mode 100644 Documentation/devicetree/bindings/gnss/u-blox.txt >> >> > >> >> > diff --git a/Documentation/devicetree/bindings/gnss/u-blox.txt b/Documentation/devicetree/bindings/gnss/u-blox.txt >> >> > new file mode 100644 >> >> > index 000000000000..bb54b83a177f >> >> > --- /dev/null >> >> > +++ b/Documentation/devicetree/bindings/gnss/u-blox.txt >> >> > @@ -0,0 +1,31 @@ >> >> > +u-blox GNSS Receiver DT binding >> >> > + >> >> > +The u-blox GNSS receivers can use UART, DDC (I2C), SPI and USB interfaces. >> >> > + >> >> > +Please see Documentation/devicetree/bindings/gnss/gnss.txt for generic >> >> > +properties. >> >> > + >> >> > +Required Properties: >> >> > + >> >> > +- compatible : Must be one of >> >> > + >> >> > + "u-blox,neo-8" >> >> > + "u-blox,neo-m8" >> >> > + >> >> > +- vcc-supply : Main voltage regulator (VCC) >> >> >> >> What about V_BCKP? >> > >> > That's the backup supply for for the RTC and batter-backed RAM. In >> > configurations where a battery is not used it should be connected to >> > VCC. >> > >> > How would you model that? I can enable a vbckp regulator at probe, but >> > what if someone then accurately describes the corresponding pin as being >> > connected to VCC? >> >> You mean how to model a battery? It would just be a 'regulator' >> because the regulator binding covers any supply really. >> >> Then you just set both rails to the same supply phandle. > > Yes, but... > >> > I guess we can check if the regulators are identical, >> > and then just have the driver ignore V_BKUP. Knowing whether there is >> > a (hopefully charged) battery connected could be useful. >> >> Regulators are ref counted, so just enable it twice. Or the driver can >> just ignore it until it supports battery backup. > > ...my point was that in case there's no backup battery, you don't want > to enable vcc (via v_bckp) at probe (and instead have the device cold > boot whenever it's used). Wouldn't that result in very long acquisition times? I guess I was thinking Vcc would be always on when running and V_bckp was just for suspend. > Hence, the driver would need to check if the v_bckp-supply is identical > to vcc and not enable the former at probe in that case (i.e. similar to > if no v_bckp had been specified and we considered it optional). I guess if that's the intended operation, then making it optional is fine. Rob > >> >> > +- timepulse-gpios : Timepulse (e.g. 1PPS) GPIO (TIMEPULSE) >> >> >> >> Why the 3rd "TIMEPULSE"? >> > >> > That's the pin name, which in this case is identical to the property >> > name, so I'll drop it here. >> >> Then what is the 2nd "Timepulse"? > > That's the generic function name. > >> Maybe just a "pin name: X" prefix so it is clear. > > For u-blox devices, where property-, function- and pin name coincide, I > could just change this to: > > +- timepulse-gpios : Timepulse GPIO > > and then for the sirfstar binding, which will be used by devices from > multiple vendors which have decided to name their pins differently, I > can add a "pin name: " prefix for clarity? Sounds good. >> > Take a look at the sirf binding; vendors use different names for their >> > timepulse pins and in that case I added the actual pin names (1PPS, TM) >> > in parenthesis after the description. >> > >> > Note that I mentioned "timepulse-gpios" in the generic binding with the >> > intent of trying to enforce a generic name for pins with such a >> > function (similarly for "enable-gpios", which I guess is already >> > established). >> >> Yes, I think that's good. >> >> Though with the enable-gpios I was debating the name for sirfstar a >> bit because it isn't the normal drive it active to enable, but rather >> a pulse to enable or disable. > > I had some concerns along those lines as well, and if you agree I'll > change the property name to on_off-gpios (or onoff-gpios) which matches > the vendor data sheets for this pin, and which I think would be better. Okay, just add a vendor prefix. And note that using '_' is discouraged. Rob -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
