Re: [RFC 3/7] dt: bindings: Add nokia-bluetooth

Sebastian Reichel
2016-08-16T23:29:44Z

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Hi Rob,

On Tue, Aug 16, 2016 at 08:51:55AM -0500, Rob Herring wrote:
> On Sat, Aug 13, 2016 at 05:14:34AM +0200, Sebastian Reichel wrote:
> > ---
> > .../devicetree/bindings/net/nokia-bluetooth.txt | 43 ++++++++++++++++++++++
> > 1 file changed, 43 insertions(+)
> > create mode 100644 Documentation/devicetree/bindings/net/nokia-bluetooth.txt
> >
> > diff --git a/Documentation/devicetree/bindings/net/nokia-bluetooth.txt b/Documentation/devicetree/bindings/net/nokia-bluetooth.txt
> > new file mode 100644
> > index 000000000000..a0fceabb4cce
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/net/nokia-bluetooth.txt
> > @@ -0,0 +1,43 @@
> > +Nokia bluetooth UART devices
> > +------
> > +
> > +Some vendors have custom versions of their chips, that can be found in Nokia
> > +devices. These chips are controlled differently, than the non-Nokia version,
> > +so a different binding is required. All chips listed here implement the Nokia
> > +H4+ protocol.
> > +
> > +Required properties:
> > +
> > + - compatible: should be one of the following:
> > + * "nokia,brcm,bcm2048"
> > + * "nokia,ti,wl1271-bluetooth"
>
> Perhaps these should be 2 separate strings. Something like
> '"nokia,n900-bt", "brcm,bcm2048"'. However, if they are in no way
> compatible with the default version from the vendors, then just a single
> string is fine, but it doesn't need to be aligned to the vendor
> compatible string. So just "nokia,n900-bcm2048" or similar is fine.

The default bcm2048 variant uses different initialization process
and does not use word alignment as far as I know. I think having
"brcm,bcm2048" in the compatible string is wrong.

I guess "brcm,bcm2048-nokia" would also be an option, since the
chip has been built buy broadcom, but it has a custom Nokia
interface.

> > + - reset-gpios: Should specify the gpio for bluetooth reset
> > + - host-wakeup-gpios: Should specify the gpio for host wakeup
>
> Should be interrupt instead?

Yes this is mostly an interrupt, but I need to read the current
line state.

> > + - bluetooth-wakeup-gpios: Should specify the gpio for bluetooth wakeup
>
> State direction and active state for gpios.

ok.

> > + - clock-names: Should be "sysclk"
> > + - clocks: Should contain a clock phandle for system clock
> > +
> > +Example:
> > +
> > +/ {
> > + /* controlled (enabled/disabled) directly by wl1271 */
> > + vctcxo: vctcxo {
> > + compatible = "fixed-clock";
> > + #clock-cells = <0>;
> > + clock-frequency = <38400000>;
> > + };
> > +};
> > +
> > +&uart2 {
>
> I want to see a common serial device binding doc before accepting any
> device bindings. It's not going to say much initially other than devices
> are child nodes of uarts. Perhaps something on baudrate settings.

Neil added a short sentence about this in "[RFC 2/7] tty: add
support for "tty slave" devices". I just took the unmodified patch
from Neil (*), so it's not in its own patch.

> > + bluetooth {
> > + compatible = "nokia,ti,wl1271-bluetooth";
> > +
> > + reset-gpios = <&gpio1 26 GPIO_ACTIVE_HIGH>; /* 26 */
> > + host-wakeup-gpios = <&gpio4 5 GPIO_ACTIVE_HIGH>; /* 101 */
> > + bluetooth-wakeup-gpios = <&gpio2 5 GPIO_ACTIVE_HIGH>; /* 37 */
> > +
> > + clocks = <&vctcxo>;
> > + clock-names = "sysclk";
> > + };
> > +
> > +};

-- Sebastian

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