Support adapter without HCI

Support adapter without HCI

[David Frey]

Is it possible to support a bluetooth adapter in the Linux kernel in
the case where the adapter doesn't present a HCI interface?  The
adapter in question was originally envisioned as a standalone host,
but I am interested in using it as an adapter (over SPI) controlled by
another CPU running Linux.  The BLE implementation on the target is a
closed source binary that provides GAP and GATT APIs.  Details of the
APIs are here: http://labs.mediatek.com/api/mt7697/group___bluetooth.html

If it *is* possible to support adapters which don't offer an HCI
interface, then I'm hoping that someone can point me at an example or
an interface definition so I can get an idea of what is required.

Thanks,
David

Re: Support adapter without HCI

[Alan Martinovic]

Hi,
I didn't get through you question what are the actual commands
that are being passed via SPI to the controller once HCI has been removed?

You want to use the API provided by the library on the controller and invoke it
directly from the host via SPI?

I saw something kind of similar from Nordic:
    https://github.com/NordicSemiconductor/pc-ble-driver

Would be willing to bet that they just invented something
that replaces HCI, but it's still a intermediate protocol that glues
together the host and controller, can't see how that can be avoided.

Be Well,
Alan





On Wed, Mar 28, 2018 at 8:02 PM, David Frey <dpfrey@gmail.com> wrote:
> Is it possible to support a bluetooth adapter in the Linux kernel in
> the case where the adapter doesn't present a HCI interface?  The
> adapter in question was originally envisioned as a standalone host,
> but I am interested in using it as an adapter (over SPI) controlled by
> another CPU running Linux.  The BLE implementation on the target is a
> closed source binary that provides GAP and GATT APIs.  Details of the
> APIs are here: http://labs.mediatek.com/api/mt7697/group___bluetooth.html
>
> If it *is* possible to support adapters which don't offer an HCI
> interface, then I'm hoping that someone can point me at an example or
> an interface definition so I can get an idea of what is required.
>
> Thanks,
> David
> --
> To unsubscribe from this list: send the line "unsubscribe linux-bluetooth" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html

Re: Support adapter without HCI

[David Frey]

Hi,

I'm sorry if I was unclear. What I would like it to be able to write
application code for Linux that uses bluez to talk to BLE devices
connected to a bluetooth adapter.  The thing that I think might be
problematic is fitting the adapter into the Linux kernel framework for
bluetooth adapters.  The SoC that I want to use as an adapter does not
present an HCI interface.  There is a closed source BLE library that
exposes GATT and GAP functions.  So my question is really whether it
is possible to support an adapter in the linux kernel that doesn't
support HCI and if it is, are there any examples of drivers like that?

If this is *not* possible, then I will probably have to define a
non-standard interface (outside of bluez) for controlling the
bluetooth feature of the chip.  That's really not ideal since any code
that users write won't be portable to other adapters.  I guess I could
try to implement the same DBus interfaces that are provided by Bluez,
but this is definitely not my first choice.

Thanks,
David

On Thu, Mar 29, 2018 at 1:10 AM, Alan Martinovic
<alan.martinovic@senic.com> wrote:
> Hi,
> I didn't get through you question what are the actual commands
> that are being passed via SPI to the controller once HCI has been removed?
>
> You want to use the API provided by the library on the controller and invoke it
> directly from the host via SPI?
>
> I saw something kind of similar from Nordic:
>     https://github.com/NordicSemiconductor/pc-ble-driver
>
> Would be willing to bet that they just invented something
> that replaces HCI, but it's still a intermediate protocol that glues
> together the host and controller, can't see how that can be avoided.
>
> Be Well,
> Alan
>
>
>
>
>
> On Wed, Mar 28, 2018 at 8:02 PM, David Frey <dpfrey@gmail.com> wrote:
>> Is it possible to support a bluetooth adapter in the Linux kernel in
>> the case where the adapter doesn't present a HCI interface?  The
>> adapter in question was originally envisioned as a standalone host,
>> but I am interested in using it as an adapter (over SPI) controlled by
>> another CPU running Linux.  The BLE implementation on the target is a
>> closed source binary that provides GAP and GATT APIs.  Details of the
>> APIs are here: http://labs.mediatek.com/api/mt7697/group___bluetooth.html
>>
>> If it *is* possible to support adapters which don't offer an HCI
>> interface, then I'm hoping that someone can point me at an example or
>> an interface definition so I can get an idea of what is required.
>>
>> Thanks,
>> David
>> --
>> To unsubscribe from this list: send the line "unsubscribe linux-bluetooth" in
>> the body of a message to majordomo@vger.kernel.org
>> More majordomo info at  http://vger.kernel.org/majordomo-info.html

Re: Support adapter without HCI

[Alan Martinovic]

> There is a closed source BLE library that
exposes GATT and GAP functions.

Can you expand on the definition on "exposes" here?
>From where to whom?


On Thu, Mar 29, 2018 at 5:38 PM, David Frey <dpfrey@gmail.com> wrote:
> Hi,
>
> I'm sorry if I was unclear. What I would like it to be able to write
> application code for Linux that uses bluez to talk to BLE devices
> connected to a bluetooth adapter.  The thing that I think might be
> problematic is fitting the adapter into the Linux kernel framework for
> bluetooth adapters.  The SoC that I want to use as an adapter does not
> present an HCI interface.  There is a closed source BLE library that
> exposes GATT and GAP functions.  So my question is really whether it
> is possible to support an adapter in the linux kernel that doesn't
> support HCI and if it is, are there any examples of drivers like that?
>
> If this is *not* possible, then I will probably have to define a
> non-standard interface (outside of bluez) for controlling the
> bluetooth feature of the chip.  That's really not ideal since any code
> that users write won't be portable to other adapters.  I guess I could
> try to implement the same DBus interfaces that are provided by Bluez,
> but this is definitely not my first choice.
>
> Thanks,
> David
>
> On Thu, Mar 29, 2018 at 1:10 AM, Alan Martinovic
> <alan.martinovic@senic.com> wrote:
>> Hi,
>> I didn't get through you question what are the actual commands
>> that are being passed via SPI to the controller once HCI has been removed?
>>
>> You want to use the API provided by the library on the controller and invoke it
>> directly from the host via SPI?
>>
>> I saw something kind of similar from Nordic:
>>     https://github.com/NordicSemiconductor/pc-ble-driver
>>
>> Would be willing to bet that they just invented something
>> that replaces HCI, but it's still a intermediate protocol that glues
>> together the host and controller, can't see how that can be avoided.
>>
>> Be Well,
>> Alan
>>
>>
>>
>>
>>
>> On Wed, Mar 28, 2018 at 8:02 PM, David Frey <dpfrey@gmail.com> wrote:
>>> Is it possible to support a bluetooth adapter in the Linux kernel in
>>> the case where the adapter doesn't present a HCI interface?  The
>>> adapter in question was originally envisioned as a standalone host,
>>> but I am interested in using it as an adapter (over SPI) controlled by
>>> another CPU running Linux.  The BLE implementation on the target is a
>>> closed source binary that provides GAP and GATT APIs.  Details of the
>>> APIs are here: http://labs.mediatek.com/api/mt7697/group___bluetooth.html
>>>
>>> If it *is* possible to support adapters which don't offer an HCI
>>> interface, then I'm hoping that someone can point me at an example or
>>> an interface definition so I can get an idea of what is required.
>>>
>>> Thanks,
>>> David
>>> --
>>> To unsubscribe from this list: send the line "unsubscribe linux-bluetooth" in
>>> the body of a message to majordomo@vger.kernel.org
>>> More majordomo info at  http://vger.kernel.org/majordomo-info.html

Re: Support adapter without HCI

[David Frey]

> > There is a closed source BLE library that
> > exposes GATT and GAP functions.
>
> Can you expand on the definition on "exposes" here?
> From where to whom?

What I meant was that there is a C API exposed by a library on the
microcontroller for doing GATT and GAP.  In order to allow Linux to
make use of this library, I will need to provide some sort of RPC
protocol over SPI or UART.