From mboxrd@z Thu Jan 1 00:00:00 1970 From: Lokesh Vutla Subject: Re: [PATCH v2 06/10] dt-bindings: irqchip: Introduce TISCI Interrupt router bindings Date: Fri, 26 Oct 2018 12:08:55 +0530 Message-ID: References: <20181018154017.7112-1-lokeshvutla@ti.com> <20181018154017.7112-7-lokeshvutla@ti.com> <20181025184556.GA19597@bogus> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8"; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20181025184556.GA19597@bogus> Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org To: Rob Herring Cc: Nishanth Menon , Santosh Shilimkar , tglx@linutronix.de, jason@lakedaemon.net, marc.zyngier@arm.com, Linux ARM Mailing List , linux-kernel@vger.kernel.org, Tero Kristo , Sekhar Nori , Device Tree Mailing List , Grygorii Strashko , Peter Ujfalusi List-Id: devicetree@vger.kernel.org Hi Rob, On Friday 26 October 2018 12:15 AM, Rob Herring wrote: > On Thu, Oct 18, 2018 at 09:10:13PM +0530, Lokesh Vutla wrote: >> Add the DT binding documentation for Interrupt router driver. >> >> Signed-off-by: Lokesh Vutla >> --- >> Changes since v1: >> - Drop dependency on GIC >> - Updated supported interrupt types. >> >> .../interrupt-controller/ti,sci-intr.txt | 81 +++++++++++++++++++ >> MAINTAINERS | 1 + >> 2 files changed, 82 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..276bb4f0ad12 >> --- /dev/null >> +++ b/Documentation/devicetree/bindings/interrupt-controller/ti,sci-intr.txt >> @@ -0,0 +1,81 @@ >> +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 | |----->| IRQ | >> + | 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 Host 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. Only level >> + sensitive trigger types are supported. >> +- interrupt-parent: phandle of irq parent for TISCI intr. > > This is implied and could be in a parent node. okay, will drop it in next version. > >> +- 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: TISCI subtype id representing the host irqs assigned >> + to this interrupt router. > > These need a better explanation and there's still some questions on v1 > asked of me that I tried to answer. Before I jump into the details, I would like to provide a brief on TISCI resource management: - Host_id: Typically it is the representation of the host processing entities (example: A53 cores running in a VM) as identified by the TISCI.[1] - Device_id: Each Device in SoC is uniquely identified by TISCI using an ID. - Each device has Resources like interrupts, DMA channels etc. A simple example would be Interrupt Router and GIC($subject). There are n physical GIC interrupts connected to Interrupt Router. Such resources are are uniquely identified by TISCI using a type ID.[2] For the sake of simplicity lets consider an Interrupt Router(IR) to which GIC line 32-63 are connected. Considering Isolation for each VM in picture, TISCI allows for a certain range within [32-63] to be assigned to a specific Host_ID. This is mainly to provide the ability for OSs running in virtual machines to be able to independently communicate with the firmware without the need going through a hypervisor. - Now for Linux to know the GIC irq range that can be used by this Interrupt router, IR driver should send a message to system-controller using TISCI protocol with the resource type as parameter. - For configuring the IRQ,(i.e. attaching an input to IR to a GIC irq), IR driver should send a message to system-controller using TISCI protocol with gic-device-id and an irq from the provided range as parameters. For covering the above two scenarios, ti,sci-dst-id and ti,sci-rm-range-girq is introduced in DT. [1] http://downloads.ti.com/tisci/esd/latest/5_soc_doc/am6x/hosts.html [2] http://downloads.ti.com/tisci/esd/latest/5_soc_doc/am6x/resasg_types.html > >> + >> +Example: >> +-------- >> +The following example demonstrates both interrupt router node and the consumer >> +node(main gpio) on the AM654 SoC: >> + >> +main_intr: interrupt-controller@1 { >> + compatible = "ti,sci-intr"; >> + interrupt-controller; >> + interrupt-parent = <&gic>; >> + #interrupt-cells = <3>; >> + ti,sci = <&dmsc>; >> + ti,sci-dst-id = <56>; >> + ti,sci-rm-range-girq = <0x1>; >> +}; >> + >> +main_gpio0: main_gpio0@600000 { > > gpio@... Sure, will fix it in next version. Thanks and regards, Lokesh