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Message-ID: <BY1PR0201MB0885F2BCD9FE353171B54888B0110@BY1PR0201MB0885.namprd02.prod.outlook.com>
Date: Wed, 10 Jan 2018 01:22:13 +0000
From: Jiaying Liang <jliang@...inx.com>
To: Jassi Brar <jassisinghbrar@...il.com>
CC: Michal Simek <michal.simek@...inx.com>,
Rob Herring <robh+dt@...nel.org>,
Mark Rutland <mark.rutland@....com>,
"linux-arm-kernel@...ts.infradead.org"
<linux-arm-kernel@...ts.infradead.org>,
Devicetree List <devicetree@...r.kernel.org>,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH v3 2/2] dt-bindings: mailbox: Add Xilinx IPI Mailbox
> -----Original Message-----
> From: Jassi Brar [mailto:jassisinghbrar@...il.com]
> Sent: Tuesday, January 09, 2018 12:00 AM
> To: Jiaying Liang <jliang@...inx.com>
> Cc: Michal Simek <michal.simek@...inx.com>; Rob Herring
> <robh+dt@...nel.org>; Mark Rutland <mark.rutland@....com>; linux-arm-
> kernel@...ts.infradead.org; Devicetree List <devicetree@...r.kernel.org>;
> Linux Kernel Mailing List <linux-kernel@...r.kernel.org>; Jiaying Liang
> <jliang@...inx.com>
> Subject: Re: [PATCH v3 2/2] dt-bindings: mailbox: Add Xilinx IPI Mailbox
>
> On Fri, Jan 5, 2018 at 5:21 AM, Wendy Liang <wendy.liang@...inx.com> wrote:
> > Xilinx ZynqMP IPI(Inter Processor Interrupt) is a hardware block in
> > ZynqMP SoC used for the communication between various processor
> > systems.
> >
> > Signed-off-by: Wendy Liang <jliang@...inx.com>
> > ---
> > .../bindings/mailbox/xlnx,zynqmp-ipi-mailbox.txt | 104
> +++++++++++++++++++++
> > 1 file changed, 104 insertions(+)
> > create mode 100644
> > Documentation/devicetree/bindings/mailbox/xlnx,zynqmp-ipi-mailbox.txt
> >
> > diff --git
> > a/Documentation/devicetree/bindings/mailbox/xlnx,zynqmp-ipi-mailbox.tx
> > t
> > b/Documentation/devicetree/bindings/mailbox/xlnx,zynqmp-ipi-
> mailbox.tx
> > t
> > new file mode 100644
> > index 0000000..5e270a3
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/mailbox/xlnx,zynqmp-ipi-
> mailbo
> > +++ x.txt
> > @@ -0,0 +1,104 @@
> > +Xilinx IPI Mailbox Controller
> > +========================================
> > +
> > +The Xilinx IPI(Inter Processor Interrupt) mailbox controller is to
> > +manage messaging between two Xilinx Zynq UltraScale+ MPSoC IPI
> > +agents. Each IPI agent owns registers used for notification and buffers for
> message.
> > +
> > + +-------------------------------------+
> > + | Xilinx ZynqMP IPI Controller |
> > + +-------------------------------------+
> > + +--------------------------------------------------+
> > +ATF | |
> > + | |
> > + | |
> > + +--------------------------+ |
> > + | |
> > + | |
> > + +--------------------------------------------------+
> > + +------------------------------------------+
> > + | +----------------+ +----------------+ |
> > +Hardware | | IPI Agent | | IPI Buffers | |
> > + | | Registers | | | |
> > + | | | | | |
> > + | +----------------+ +----------------+ |
> > + | |
> > + | Xilinx IPI Agent Block |
> > + +------------------------------------------+
> > +
> > +
> > +Controller Device Node:
> > +===========================
> > +Required properties:
> > +--------------------
> > +- compatible: Shall be: "xlnx,zynqmp-ipi-mailbox"
> > +- reg: IPI buffers address ranges
> > +- reg-names: Names of the reg resources. It should have:
> > + * local_request_region
> > + - IPI request msg buffer written by local and read
> > + by remote
> > + * local_response_region
> > + - IPI response msg buffer written by local and read
> > + by remote
> > + * remote_request_region
> > + - IPI request msg buffer written by remote and read
> > + by local
> > + * remote_response_region
> > + - IPI response msg buffer written by remote and read
> > + by local
> >
> shmem is option and external to the controller. It should be passed via
> client's binding.
> Please have a look at Sudeep's proposed patch
> https://www.spinics.net/lists/arm-kernel/msg626120.html
[Wendy] thanks for the link, but those 'buffers" are registers in the hardware
but not memory. It looks like a bit hacky to access them as memory.
>
> > +- #mbox-cells: Shall be 1. It contains:
> > + * tx(0) or rx(1) channel
> > +- xlnx,ipi-ids: Xilinx IPI agent IDs of the two peers of the
> > + Xilinx IPI communication channel.
> > +- interrupt-parent: Phandle for the interrupt controller
> > +- interrupts: Interrupt information corresponding to the
> > + interrupt-names property.
> > +
> > +Optional properties:
> > +--------------------
> > +- method: The method of accessing the IPI agent registers.
> > + Permitted values are: "smc" and "hvc". Default is
> > + "smc".
> > +
> Andre almost implemented the generic driver. Can you please have a look at
> https://www.spinics.net/lists/arm-kernel/msg595416.html
> and see if you can just finish it off?
[Wendy] This mailbox controller is about to use Xilinx IPI hardware as mailbox.
We use it to send notification/short request to firmware (usually running on
another core on SoC), and also to receive notification/short request from firmware.
Interrupt is used in the receiving direction. It looks different to the usage of
mailbox driver from the link. Is there a plan to extend the ARM SMC mailbox driver
to both trigger firmware actions and receive request from firmware?
Thanks,
Wendy
>
> Thanks
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