Re: BCM2048 bluetooth connected over OMAP serial

[Mark Rutland <mark.rutland@arm.com>]

On Wed, Dec 10, 2014 at 05:02:42PM +0000, Arnd Bergmann wrote:
> On Wednesday 10 December 2014 17:43:33 Pavel Machek wrote:
> > 
> > So, there's bluetooth chip that's connected to the SoC by UART and some
> > GPIOs. What would be right representation in the device tree?
> > Something like this?
> > 
> >         bluetooth {
> >                   compatible = "broadcom,bcm2048";
> >                   uart = <&uart2>;
> >                   reset-gpios = <&gpio3 27 GPIO_ACTIVE_HIGH>; /* want 91 */
> >                   host-wakeup-gpios = <&gpio4 5 GPIO_ACTIVE_HIGH>; /* want 101 */
> >                   bluetooth-wakeup-gpios = <&gpio2 5 GPIO_ACTIVE_HIGH>; /* want 37 */
> >                   chip-type = >;
> >                   bt-sysclk = <2>;
> >                   reset-gpio-shared = <0>;
> >         };
> > 
> > Is there some way to prevent OMAP tty driver from binding to the
> > device and exporting the device to userspace?
> 
> I think from the driver perspective, you want this to be a tty line
> discipline rather than a driver that attaches to the physical
> uart.
> 
> For the DT representation, I fear we haven't got a precedent. A uart
> phandle sounds reasonable, but there might be other ways to do it
> and we should consider if there are better alternatives. It could
> possibly be a child node of the uart, but that would require other
> infrastructure in the kernel because we don't currently create
> devices for those.

I think the child node is the way to go; that would match what we do for
I2C and SPI. We might need new infrastructure, but I don't think we
should treat this differently simlpy because we don't have that yet.

Mark.