Hi Rob, On Fri, 5 Feb 2021 at 07:25, Rob Herring <robh@xxxxxxxxxx> wrote: > > On Wed, Feb 03, 2021 at 05:07:26PM +0800, Chunyan Zhang wrote: > > From: Chunyan Zhang <chunyan.zhang@xxxxxxxxxx> > > > > This iommu module can be used by Unisoc's multimedia devices, such as > > display, Image codec(jpeg) and a few signal processors, including > > VSP(video), GSP(graphic), ISP(image), and CPP(camera pixel processor), etc. > > > > Signed-off-by: Chunyan Zhang <chunyan.zhang@xxxxxxxxxx> > > --- > > .../devicetree/bindings/iommu/sprd,iommu.yaml | 72 +++++++++++++++++++ > > 1 file changed, 72 insertions(+) > > create mode 100644 Documentation/devicetree/bindings/iommu/sprd,iommu.yaml > > > > diff --git a/Documentation/devicetree/bindings/iommu/sprd,iommu.yaml b/Documentation/devicetree/bindings/iommu/sprd,iommu.yaml > > new file mode 100644 > > index 000000000000..4fc99e81fa66 > > --- /dev/null > > +++ b/Documentation/devicetree/bindings/iommu/sprd,iommu.yaml > > @@ -0,0 +1,72 @@ > > +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause) > > +# Copyright 2020 Unisoc Inc. > > +%YAML 1.2 > > +--- > > +$id: http://devicetree.org/schemas/iommu/sprd,iommu.yaml# > > +$schema: http://devicetree.org/meta-schemas/core.yaml# > > + > > +title: Unisoc IOMMU and Multi-media MMU > > + > > +maintainers: > > + - Chunyan Zhang <zhang.lyra@xxxxxxxxx> > > + > > +properties: > > + compatible: > > + enum: > > + - sprd,iommu-v1 > > + > > + "#iommu-cells": > > + const: 0 > > + description: > > + Unisoc IOMMUs are all single-master IOMMU devices, therefore no > > + additional information needs to associate with its master device. > > + Please refer to the generic bindings document for more details, > > + Documentation/devicetree/bindings/iommu/iommu.txt > > + > > + reg: > > + maxItems: 1 > > + description: > > + Not required if 'sprd,iommu-regs' is defined. > > + > > + clocks: > > + description: > > + Reference to a gate clock phandle, since access to some of IOMMUs are > > + controlled by gate clock, but this is not required. > > + > > + sprd,iommu-regs: > > + $ref: /schemas/types.yaml#/definitions/phandle-array > > + description: > > + Reference to a syscon phandle plus 1 cell, the syscon defines the > > + register range used by the iommu and the media device, the cell > > + defines the offset for iommu registers. Since iommu module shares > > + the same register range with the media device which uses it. > > + > > +required: > > + - compatible > > + - "#iommu-cells" > > + > > +oneOf: > > + - required: > > + - reg > > + - required: > > + - sprd,iommu-regs > > + > > +additionalProperties: false > > + > > +examples: > > + - | > > + iommu_disp: iommu-disp { > > + compatible = "sprd,iommu-v1"; > > + sprd,iommu-regs = <&dpu_regs 0x800>; > > If the IOMMU is contained within another device, then it should just be > a child node of that device. Yes, actually IOMMU can be seen as a child of multimedia devices, I considered moving IOMMU under into multimedia device node, but multimedia devices need IOMMU when probe[1], so I dropped that idea. And they share the same register base, e.g. + mm { + compatible = "simple-bus"; + #address-cells = <2>; + #size-cells = <2>; + ranges; + + dpu_regs: syscon@63000000 { + compatible = "sprd,sc9863a-dpuregs", "syscon"; + reg = <0 0x63000000 0 0x1000>; + }; + + dpu: dpu@63000000 { + compatible = "sprd,sharkl3-dpu"; + sprd,disp-regs = <&dpu_regs>; + iommus = <&iommu_dispc>; + }; + + iommu_dispc: iommu@63000000 { + compatible = "sprd,iommu-v1"; + sprd,iommu-regs = <&dpu_regs 0x800>; + #iommu-cells = <0>; + }; DPU use the registers from 0, IOMMU from 0x800, the purpose of using syscon node was to avoid remapping register physical address. > Or just make 'dpu_regs' an IOMMU provider > (i.e. just add #iommu-cells to it). xxx_regs(syscon node) defines the register range for IOMMU and a multimedia device (such as dpu, image codec, etc.) Hope I've explained the relationship of xxx_regs, multimedia device, and iommu clearly :) Any suggestion for this kind of cases? Thanks, Chunyan [1] https://elixir.bootlin.com/linux/v5.11-rc6/source/drivers/iommu/of_iommu.c#L145 > > > + #iommu-cells = <0>; > > + }; > > + > > + - | > > + iommu_jpg: iommu-jpg { > > + compatible = "sprd,iommu-v1"; > > + sprd,iommu-regs = <&jpg_regs 0x300>; > > + #iommu-cells = <0>; > > + clocks = <&mm_gate 1>; > > + }; > > + > > +... > > -- > > 2.25.1 > >
