Re: [PATCH v3 1/3] dt-bindings: net: bluetooth: Add broadcom-bluetooth

[Eric Anholt <eric@anholt.net>]

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Rob Herring <robh+dt@kernel.org> writes:

> On Mon, Aug 7, 2017 at 5:39 AM, Loic Poulain <loic.poulain@gmail.com> wrote:
>> Add binding document for serial bluetooth chips using
>> Broadcom protocol.
>>
>> Signed-off-by: Loic Poulain <loic.poulain@gmail.com>
>> ---
>>  v2: dt-bindings as separate patch
>>      rebase on upcoming pi3 dts changes
>>  v3: changes in bcm serdev drivers:
>>      name refactoring and additional comments
>>      Add generic host_set_baudrate method
>>      Use agnostic device_property_read
>>  .../devicetree/bindings/net/broadcom-bluetooth.txt | 29 ++++++++++++++++++++++
>>  1 file changed, 29 insertions(+)
>>  create mode 100644 Documentation/devicetree/bindings/net/broadcom-bluetooth.txt
>>
>> diff --git a/Documentation/devicetree/bindings/net/broadcom-bluetooth.txt b/Documentation/devicetree/bindings/net/broadcom-bluetooth.txt
>> new file mode 100644
>> index 0000000..c51ea1b
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/net/broadcom-bluetooth.txt
>> @@ -0,0 +1,29 @@
>> +Broadcom Bluetooth Chips
>> +---------------------
>> +
>> +This documents the binding structure and common properties for serial
>> +attached Broadcom devices.
>> +
>> +Serial attached Broadcom devices shall be a child node of the host UART
>> +device the slave device is attached to.
>> +
>> +Required properties:
>> +
>> + - compatible: should contain one of the following:
>> +   * "brcm,bcm43438-bt"
>> +
>> +Optional properties:
>
> Most Broadcom devices have a couple of GPIOs needing control. Maybe
> they are tied off active on RPi3, but you should document them here
> even if the driver doesn't yet need them. I think they are the same as
> the Nokia BT IIRC. Same goes for any input clocks.

As far as the clock goes, I think it would be a reference to <&cprman
BCM2835_CLOCK_GP2>, and the clock should be at 32Khz.  (This is already
set up at boot by the firmware).

In the schematics I have, there are two GPIO lines going to the chip:
BT_ON (expander gpio 0) and WL_ON (expander gpio 1).  We don't have
support for the expander yet, and they are already enabled at boot time,
so hopefully they can be optional properties.

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