On 13/02/19 9:02 PM, Tony Lindgren wrote:
> * Lokesh Vutla <lokeshvu...@ti.com> [190213 04:23]:
>> Hi Tony,
>>
>> On 12/02/19 10:00 PM, Tony Lindgren wrote:
>>> Hi,
>>>
>>> * Lokesh Vutla <lokeshvu...@ti.com> [190212 07:43]:
>>>> +The Interrupt Router (INTR) module provides a mechanism to route 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 | |
>>>> + | +-----+ |
>>>> + +----------------------+
>>>
>>> Is this always one-to-one mapping or can the same interrupt be routed to
>>> multiple targets like to the SoC and some coprocessor?
>>
>> Yes, it is always one-to-one. Output of INTR can only be attached to one of
>> the
>> processor.
>
> OK
>
>>>> +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
>>>
>>> Care to describe a bit why the interrupts need to be routed by a system
>>> controller?
>>
>> K3 architecture defines a heterogeneous system where multiple heterogeneous
>> cores are serving its own usecases. Given that there are multiple ways in
>> which
>> a device IRQ can be routed using INTR, like either it can be routed to HLOS
>> core(A53 int this case) or it can be routed to any other coprocessor
>> available
>> in the system(like R5). If every sw running in each co-processor is allowed
>> to
>> program this INTR then there is a high probability that one sw executing on
>> one
>> core can damage other heterogeneous core. Mainly to avoid this damage the
>> configuration of all the INTRs and INTAs are done in a centralized
>> place(sysfw).
>> Any user for programming its IRQ route should send a message to sysfw with
>> the
>> parameters. These parameters are policed by sysfw and does the configuration.
>
> OK so maybe update the description along those lines saying it's
> a shared piece of hardware between various independent SoC
> clusters which may or may not be running Linux.
IMHO, SoC integration is out of scope of this document. If you insist I can add
the details.
Thanks and regards,
Lokesh
