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SubjectRe: [PATCH 1/2] dt-bindings: irqchip: Introduce TISCI Interrupt router bindings
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
--
Regards,
Nishanth Menon

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