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). 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). > >> > +- 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? > > 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. Thanks, Johan -- 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
