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SubjectRe: [PATCH 1/2] dt-bindings: irqchip: Introduce TISCI Interrupt router bindings
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Hi Rob, DT maintainers,

On Saturday 06 October 2018 09:59 PM, Nishanth Menon wrote:
> On 12:58-20181006, Lokesh Vutla wrote:
>> Add the DT binding documentation for Interrupt router driver.
>>
>> Signed-off-by: Lokesh Vutla <lokeshvutla@ti.com>
>> ---
>> .../interrupt-controller/ti,sci-intr.txt | 83 +++++++++++++++++++
>> MAINTAINERS | 1 +
>> 2 files changed, 84 insertions(+)
>> create mode 100644 Documentation/devicetree/bindings/interrupt-controller/ti,sci-intr.txt
>>
>> diff --git a/Documentation/devicetree/bindings/interrupt-controller/ti,sci-intr.txt b/Documentation/devicetree/bindings/interrupt-controller/ti,sci-intr.txt
>> new file mode 100644
>> index 000000000000..681ca53cc5fb
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/interrupt-controller/ti,sci-intr.txt
>> @@ -0,0 +1,83 @@
>> +Texas Instruments K3 Interrupt Router
>> +=====================================
>> +
>> +The Interrupt Router (INTR) module provides a mechanism to mux M
>> +interrupt inputs to N interrupt outputs, where all M inputs are selectable
>> +to be driven per N output. There is one register per output (MUXCNTL_N) that
>> +controls the selection.
>> +
>> +
>> + Interrupt Router
>> + +----------------------+
>> + | Inputs Outputs |
>> + +-------+ | +------+ |
>> + | GPIO |----------->| | irq0 | | Host IRQ
>> + +-------+ | +------+ | controller
>> + | . +-----+ | +-------+
>> + +-------+ | . | 0 | |----->| GIC |
>> + | INTA |----------->| . +-----+ | +-------+
>> + +-------+ | . . |
>> + | +------+ . |
>> + | | irqM | +-----+ |
>> + | +------+ | N | |
>> + | +-----+ |
>> + +----------------------+
>> +
>> +Configuration of these MUXCNTL_N registers is done by a system controller
>> +(like the Device Memory and Security Controller on K3 AM654 SoC). System
>> +controller will keep track of the used and unused registers within the Router.
>> +Driver should request the system controller to get the range of GIC IRQs
>> +assigned to the requesting hosts. It is the drivers responsibility to keep
>> +track of GIC IRQs.
>> +
>> +Communication between the host processor running an OS and the system
>> +controller happens through a protocol called TI System Control Interface
>> +(TISCI protocol). For more details refer:
>> +Documentation/devicetree/bindings/arm/keystone/ti,sci.txt
>> +
>> +TISCI Interrupt Router Node:
>> +----------------------------
>> +- compatible: Must be "ti,sci-intr".
>> +- interrupt-controller: Identifies the node as an interrupt controller
>> +- #interrupt-cells: Specifies the number of cells needed to encode an
>> + interrupt source. The value should be 3.
>> + First cell should contain the TISCI device ID of source
>> + Second cell should contain the interrupt source offset
>> + within the device
>> + Third cell specifies the trigger type as defined
>> + in interrupts.txt in this directory.
>> +- interrupt-parent: phandle of irq parent for TISCI intr. The parent must
>> + use the same interrupt-cells format as GIC.
>> +- ti,sci: Phandle to TI-SCI compatible System controller node.
>> +- ti,sci-dst-id: TISCI device ID of the destination IRQ controller.
>> +- ti,sci-rm-range-girq: Tuple corresponding to unique TISCI resource type that
>> + defines the dst host irq ranges assigned to this
>> + interrupt router from this host context.
>> + Tuple should be of format <type subtype>.
>> +
>
> Rob, DT maintainers,
>
> I'd like a feedback from DT maintainers on this 'range' topic.
>
> TISCI Firmware [1] currently seems to define a type corresponding to a
> device ID[2]. in AM6 device, for example, this is different, however
> have a 1 to 1 correspondence. However, there is expectation that type will
> end up as device ID in a future SoC.
>
> While this is subject to much debate internally, I'd like some feedback if this
> is OK from Device tree representation - it is true that Firmware does
> look at it as type, however in some future SoC, it could be that the
> values themselves may correspond one to one with a device id -> The
> original wish was that types might be something reusable across SoCs,
> but that is turning out to be more of a theoretical wish than any thing
> practical.
>
> [1]http://software-dl.ti.com/tisci/esd/latest/5_soc_doc/am6x/resasg_types.html
> [2]http://software-dl.ti.com/tisci/esd/latest/5_soc_doc/am6x/devices.html

Any help on this topic?

Thanks and regards,
Lokesh

>

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