Re: [PATCH 1/2] bcma: register bcma as device tree driver

[Arend van Spriel <arend-dY08KVG/lbpWk0Htik3J/w@public.gmane.org>]

On 09/13/14 18:02, Hauke Mehrtens wrote:
> On 09/13/2014 05:13 PM, Arend van Spriel wrote:
>> On 09/13/14 15:37, Hauke Mehrtens wrote:
>>> This driver is used by the bcm53xx ARM SoC code. Now it is possible to
>>> give the address of the chipcommon core in device tree and bcma will
>>> search for all the other cores.
>>>
>>> Signed-off-by: Hauke Mehrtens<hauke-5/S+JYg5SzeELgA04lAiVw@public.gmane.org>
>>> ---
>>>    Documentation/devicetree/bindings/bus/bcma.txt | 41 +++++++++++++
>>>    drivers/bcma/bcma_private.h                    | 16 +++++
>>>    drivers/bcma/host_soc.c                        | 82
>>> ++++++++++++++++++++++++++
>>>    drivers/bcma/main.c                            | 10 ++++
>>>    include/linux/bcma/bcma.h                      |  2 +
>>>    5 files changed, 151 insertions(+)
>>>    create mode 100644 Documentation/devicetree/bindings/bus/bcma.txt
>>>
>>> This is based on wireless-testing and should go into that tree.
>>>
>>> changes since:
>>> RFC:
>>>    - reworded the irq description
>>>    - improved the example
>>>    - hocked into bcma_modeinit() and bcma_modexit()
>>>
>>> diff --git a/Documentation/devicetree/bindings/bus/bcma.txt
>>> b/Documentation/devicetree/bindings/bus/bcma.txt
>>> new file mode 100644
>>> index 0000000..17e095f
>>> --- /dev/null
>>> +++ b/Documentation/devicetree/bindings/bus/bcma.txt
>>> @@ -0,0 +1,41 @@
>>> +Broadcom AIX SoC bcma bus driver
>>
>> Hi Hauke,
>>
>> First of all a typo used all over the place: AIX should be AXI.
>
> I will fix that.
>
>> The backplane in Broadcom SoC is ARM AXI with additional plugin option
>> to make it discoverable. Indeed the IRQ info is not included, but I see
>> no reason for specifying the register space for the cores in device-tree
>> as that is discoverable by bcma.
>
> I specified the register space to make it possible to connect the device
> tree entry with the core. After the cores are automatically discovered,
> bcma searches for entry core found, for an device tree entry with the
> same address space and uses the irq number from that entry. If there is
> a core defined in device tree which is not found by bcma it will just be
> ignored. If a core is not specified in device tree it will get
> registered, but it will not get an IRQ.
> This was the most stable way I came up with, I also thought about using
> the core number, like assign the this IRQ to core number 5, but the core
> numbers could change when we do changes to bcma.

I understand. In the example I noticed the core base address was also 
used in the entry label, ie. pcie@18002000. However, I am not sure 
whether that can be obtained by the driver. If it is possible it could 
be used to match the dt entry to a core and the register info would be 
redundant.

> In the Broadcom vendor code there is a list with the IRQ numbers which
> get assigned to a specific core type. For example there is a list with 4
> IRQ numbers which get assigned to the first 4 Ethernet cores. This would
> also work, but I do not know how to do this in device tree.

I am wondering about the IRQ numbers. The SoC would also have a OOB 
routing core, which controls non-axi signals between the cores. I will 
ask internally whether the irq signals are controlled by it and can be 
retrieved from it.

Regards,
Arend
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