Re: [PATCH v16 4/5] dt-bindings: remoteproc: Add documentation for ZynqMP R5 rproc bindings

From: Rob Herring
Date: Thu Nov 05 2020 - 14:42:16 EST

On Wed, Sep 30, 2020 at 11:21 AM Ben Levinsky <BLEVINSK@xxxxxxxxxx> wrote:
>
> Hi Rob,
>
> > -----Original Message-----
> > From: Rob Herring <robh@xxxxxxxxxx>
> > Sent: Tuesday, September 29, 2020 11:36 AM
> > To: Ben Levinsky <BLEVINSK@xxxxxxxxxx>
> > Cc: Stefano Stabellini <stefanos@xxxxxxxxxx>; Michal Simek
> > <michals@xxxxxxxxxx>; michael.auchter@xxxxxx; devicetree@xxxxxxxxxxxxxxx;
> > mathieu.poirier@xxxxxxxxxx; Ed T. Mooring <emooring@xxxxxxxxxx>; linux-
> > remoteproc@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; linux-arm-
> > kernel@xxxxxxxxxxxxxxxxxxx; Jason Wu <j.wu@xxxxxxxxxx>; Jiaying Liang
> > <jliang@xxxxxxxxxx>; Michal Simek <michals@xxxxxxxxxx>
> > Subject: Re: [PATCH v16 4/5] dt-bindings: remoteproc: Add documentation for
> > ZynqMP R5 rproc bindings
> >
> > On Tue, Sep 22, 2020 at 03:39:29PM -0700, Ben Levinsky wrote:
> > > Add binding for ZynqMP R5 OpenAMP.
> > >
> > > Represent the RPU domain resources in one device node. Each RPU
> > > processor is a subnode of the top RPU domain node.
> > >
> > > Signed-off-by: Jason Wu <j.wu@xxxxxxxxxx>
> > > Signed-off-by: Wendy Liang <jliang@xxxxxxxxxx>
> > > Signed-off-by: Michal Simek <michal.simek@xxxxxxxxxx>
> > > Signed-off-by: Ben Levinsky <ben.levinsky@xxxxxxxxxx>
> > > ---
> > > v3:
> > > - update zynqmp_r5 yaml parsing to not raise warnings for extra
> > > information in children of R5 node. The warning "node has a unit
> > > name, but no reg or ranges property" will still be raised though
> > > as this particular node is needed to describe the
> > > '#address-cells' and '#size-cells' information.
> > > v4::
> > > - remove warning '/example-0/rpu@ff9a0000/r5@0:
> > > node has a unit name, but no reg or ranges property'
> > > by adding reg to r5 node.
> > > v5:
> > > - update device tree sample and yaml parsing to not raise any warnings
> > > - description for memory-region in yaml parsing
> > > - compatible string in yaml parsing for TCM
> > > v6:
> > > - remove coupling TCM nodes with remoteproc
> > > - remove mailbox as it is optional not needed
> > > v7:
> > > - change lockstep-mode to xlnx,cluster-mode
> > > v9:
> > > - show example IPC nodes and tcm bank nodes
> > > v11:
> > > - add property meta-memory-regions to illustrate link
> > > between r5 and TCM banks
> > > - update so no warnings from 'make dt_binding_check'
> > > v14:
> > > - concerns were raised about the new property meta-memory-regions.
> > > There is no clear direction so for the moment I kept it in the series
> > > - place IPC nodes in RAM in the reserved memory section
> > > v15:
> > > - change lockstep-mode prop as follows: if present, then RPU cluster is in
> > > lockstep mode. if not present, cluster is in split mode.
> > > ---
> > > .../xilinx,zynqmp-r5-remoteproc.yaml | 120 ++++++++++++++++++
> > > 1 file changed, 120 insertions(+)
> > > create mode 100644
> > Documentation/devicetree/bindings/remoteproc/xilinx,zynqmp-r5-
> > remoteproc.yaml
> > >
> > > diff --git a/Documentation/devicetree/bindings/remoteproc/xilinx,zynqmp-
> > r5-remoteproc.yaml
> > b/Documentation/devicetree/bindings/remoteproc/xilinx,zynqmp-r5-
> > remoteproc.yaml
> > > new file mode 100644
> > > index 000000000000..ce02e425692e
> > > --- /dev/null
> > > +++ b/Documentation/devicetree/bindings/remoteproc/xilinx,zynqmp-r5-
> > remoteproc.yaml
> > > @@ -0,0 +1,120 @@
> > > +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
> > > +%YAML 1.2
> > > +---
> > > +$id: "http://devicetree.org/schemas/remoteproc/xilinx,zynqmp-r5-
> > remoteproc.yaml#"
> > > +$schema: "http://devicetree.org/meta-schemas/core.yaml#";
> > > +
> > > +title: Xilinx R5 remote processor controller bindings
> > > +
> > > +description:
> > > + This document defines the binding for the remoteproc component that
> > loads and
> > > + boots firmwares on the Xilinx Zynqmp and Versal family chipset.
> > > +
> > > + Note that the Linux has global addressing view of the R5-related memory
> > (TCM)
> > > + so the absolute address ranges are provided in TCM reg's.
> >
> > blank line needed.
> >
> will fix in next rev.
> > TCMs specifically I'm concerned about how they are represented in system
> > DT and here...
> >
> So System DT can tie in with lopper plugin/assists so that TCMs are output to whatever the linux driver expects.

Sorry, I don't buy lopper can handle it. That leaves too much hand waving IMO.

> > > +maintainers:
> > > + - Ed Mooring <ed.mooring@xxxxxxxxxx>
> > > + - Ben Levinsky <ben.levinsky@xxxxxxxxxx>
> > > +
> > > +properties:
> > > + compatible:
> > > + const: "xlnx,zynqmp-r5-remoteproc-1.0"
> >
> > Don't need quotes.
> >
> will fix in next rev.
> > The use of version numbers was allowed for Xilinx programmable IP. I
> > don't think this falls into that category.
> >
> will fix in next rev.
> > > +
> > > + lockstep-mode:
> > > + description:
> > > + If this property is present, then the configuration is lock-step.
> >
> > boolean...
> >
> By this comment do you mean you want this to change or mention that it is implicitly Boolean?

You defining this as a boolean and then using a schema that applies to
arrays (maxItems).

> > > + Otherwise RPU is split.
> > > + maxItems: 1
> >
> > ...or an array?
> >
> > Either way, doesn't work for TI R5.
> >
> So as the configuration for both the TI R5 and Xilinx R5 is independent what in common would you like to see here?
> For example Xilinx driver can similarly have the "Xilinx,cluster-mode" or "cluster-mode" but for Xilinx platform manager our split configuration value in Xilinx platform manager is '0' while in TI drver it is '1'. So I can make the driver expect it then translate if needed if this what you prefer.

What's Xilinx platform manager? The drivers are irrelevant for the binding.

>
> Otherwise how would you suggest the Xilinx r5 remoteproc driver describe split/lockstep mode?

For what's clearly the same functionality, I want the binding the
same. TI can have more modes if that's what they need.

> > > +
> > > + interrupts:
> > > + description:
> > > + Interrupt mapping for remoteproc IPI. It is required if the
> > > + user uses the remoteproc driver with the RPMsg kernel driver.
> > > + maxItems: 6
> > > +
> > > + memory-region:
> > > + description:
> > > + collection of memory carveouts used for elf-loading and inter-processor
> > > + communication.
> > > + maxItems: 4
> > > + minItems: 4
> >
> > Need to define what each region is.
> >
> > One blank line between properties.
> >
> will fix in next rev. for memory-regions is the following ok?
> collection of phandles for memory carveouts for elf-loading and
> inter-processor communication.
>
> This collection can consist of reserved-mem carveouts in DDR.

No.

items:
- description: This is the 1st entry...
- description: This is the 2nd entry...
...

>
> > > + meta-memory-regions:
> > > + description:
> > > + collection of memories that are not present in the top level memory
> > > + nodes' mapping. For example, R5s' TCM banks. These banks are needed
> > > + for R5 firmware meta data such as the R5 firmware's heap and stack
> >
> > Humm, needs a better explanation.
> How is the following:
> Collection of phandles for reserved on-chip SRAM regions.
>
>
> Otherwise I can get rid of this property and combine into memory-region if you wish.

Not sure really.

> > > + pnode-id:
> > > + maxItems: 1
> >
> > What's this?
> >
> Can add the following:
> power node id that is used to uniquely identify the RPU for Xilinx
> Power Management. The value is then passed to Xilinx platform
> manager for power on/off and access.

Sounds like you should be using the power-domain binding.

> > > + mboxes:
> > > + maxItems: 2
> >
> > Need to define what each one is.
> >
> How is the following:
> array of phandles that describe the rx and tx for xilinx zynqmp
> mailbox driver. order of rx and tx is described by the mbox-names
> property. This will be used for communication with remote
> processor.
> > > + mbox-names:
> > > + maxItems: 2
> >
> > Need to define the names.
> >
> How is the following:
> array of strings that denote which item in the mboxes property array
> are the rx and tx for xilinx zynqmp mailbox driver

Terrible. We have a schema to define constraints.

items:
- const: rx
- const: tx


> > > +
> > > +examples:
> > > + - |
> > > + reserved-memory {
> > > + #address-cells = <1>;
> > > + #size-cells = <1>;
> > > + ranges;
> > > + elf_load: rproc@3ed000000 {
> > > + no-map;
> > > + reg = <0x3ed00000 0x40000>;
> > > + };
> > > +
> > > + rpu0vdev0vring0: rpu0vdev0vring0@3ed40000 {
> > > + no-map;
> > > + reg = <0x3ed40000 0x4000>;
> > > + };
> > > + rpu0vdev0vring1: rpu0vdev0vring1@3ed44000 {
> > > + no-map;
> > > + reg = <0x3ed44000 0x4000>;
> > > + };
> > > + rpu0vdev0buffer: rpu0vdev0buffer@3ed48000 {
> > > + no-map;
> > > + reg = <0x3ed48000 0x100000>;
> > > + };
> > > +
> > > + };
> > > +
> > > + /*
> > > + * Below nodes are required if using TCM to load R5 firmware
> > > + * if not, then either do not provide nodes are label as disabled in
> > > + * status property
> > > + */
> > > + tcm0a: tcm_0a@ffe00000 {
> > > + reg = <0xffe00000 0x10000>;
> > > + pnode-id = <0xf>;
> > > + no-map;
> > > + status = "okay";
> > > + phandle = <0x40>;
> > > + compatible = "xlnx,tcm";
> >
> > TCM is a Xilinx specific thing?
> >
> No... good point. Can remove the compatible string in next rev.

Well, it should probably have some sort of compatible so we know what
the thing is...

If we have a DT for the R5 side or view of the system, we'd need to
define TCMs, right? For the A cores, it shouldn't look any different
other than perhaps the address. So, you first need a TCM binding.
Maybe that ends up being just mmio-sram binding, maybe not. Probably
not if there's power controls.

> > > + };
> > > + tcm0b: tcm_1a@ffe20000 {
> > > + reg = <0xffe20000 0x10000>;
> > > + pnode-id = <0x10>;
> > > + no-map;
> > > + status = "okay";
> > > + compatible = "xlnx,tcm";
> > > + phandle = <0x41>;
> > > + };
> > > +
> > > + rpu {
> > > + compatible = "xlnx,zynqmp-r5-remoteproc-1.0";
> > > + #address-cells = <1>;
> > > + #size-cells = <1>;
> > > + ranges;
> > > + lockstep-mode;
> > > + r5_0 {
> > > + ranges;
> > > + #address-cells = <1>;
> > > + #size-cells = <1>;
> > > + memory-region = <&elf_load>,
> > > + <&rpu0vdev0vring0>,
> > > + <&rpu0vdev0vring1>,
> > > + <&rpu0vdev0buffer>;
> > > + meta-memory-regions = <&tcm_0a>, <&tcm_0b>;
> > > + pnode-id = <0x7>;
> > > + };
> > > + };
> > > +
> > > +...
> > > --
> > > 2.17.1
> > >
> Thank you,
> Ben
>
>