On Tue, Feb 14, 2023 at 03:10:53PM +0100, Martin Povišer wrote: > Describe the SIO coprocessor which serves as pretend DMA controller on > recent Apple platforms. > > Signed-off-by: Martin Povišer <povik+lin@xxxxxxxxxxx> > --- > > Since the schema mentions a loader preparing the binding appropriately, > here's a PR with the relevant (WIP) loader code, if anyone wants to look: > https://github.com/AsahiLinux/m1n1/pull/286 > > .../devicetree/bindings/dma/apple,sio.yaml | 129 ++++++++++++++++++ > 1 file changed, 129 insertions(+) > create mode 100644 Documentation/devicetree/bindings/dma/apple,sio.yaml > > diff --git a/Documentation/devicetree/bindings/dma/apple,sio.yaml b/Documentation/devicetree/bindings/dma/apple,sio.yaml > new file mode 100644 > index 000000000000..a76cc8265e76 > --- /dev/null > +++ b/Documentation/devicetree/bindings/dma/apple,sio.yaml > @@ -0,0 +1,129 @@ > +# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause > +%YAML 1.2 > +--- > +$id: http://devicetree.org/schemas/dma/apple,sio.yaml# > +$schema: http://devicetree.org/meta-schemas/core.yaml# > + > +title: Apple SIO Coprocessor > + > +description: | Don't need '|'. > + SIO is a coprocessor on Apple M1 and later chips (and maybe also on earlier > + chips). Its role is to offload SPI, UART and DisplayPort audio transfers, > + being a pretend DMA controller. > + > +maintainers: > + - Martin Povišer <povik+lin@xxxxxxxxxxx> > + > +allOf: > + - $ref: "dma-controller.yaml#" Drop quotes. > + > +properties: > + compatible: > + items: > + - enum: > + - apple,t6000-sio > + - apple,t8103-sio > + - const: apple,sio > + > + reg: > + maxItems: 1 > + > + '#dma-cells': > + const: 1 > + description: > + DMA clients specify a single cell that corresponds to the RTKit endpoint > + number used for arranging the transfers in question > + > + dma-channels: > + maximum: 128 > + > + mboxes: > + maxItems: 1 > + > + iommus: > + maxItems: 1 > + > + power-domains: > + maxItems: 1 > + > + memory-region: > + description: > + A number of references to reserved memory regions among which are the DATA/TEXT > + sections of coprocessor executable firmware and also auxiliary firmware data > + describing the available DMA-enabled peripherals Can you define some range of number of entries. > + > + apple,sio-firmware-params: > + $ref: /schemas/types.yaml#/definitions/uint32-array > + description: | > + Parameters in the form of opaque key/value pairs that are to be sent to the SIO > + coprocesssor once it boots. These parameters can refer to the reserved memory > + regions described in 'memory-region'. > + > + Note that unlike Apple's firmware, we treat the parameters, and the data they > + refer to, as opaque. Apple embed short data blobs into their SIO devicetree node > + that describe the DMA-enabled peripherals (presumably with defined semantics). > + Their driver processes those blobs and sets up data structure in mapped device > + memory, then references this memory in the parameters sent to the SIO. At the > + level of description we are opting for in this binding, we assume the job of > + constructing those data structures has been done in advance, leaving behind an > + opaque list of key/value parameter pairs to be sent by a prospective driver. > + > + This approach is chosen for two reasons: > + > + - It means we don't need to try to understand the semantics of Apple's blobs > + as long as we know the transformation we need to do from Apple's devicetree > + data to SIO data (which can be shoved away into a loader). It also means the > + semantics of Apple's blobs (or of something to replace them) need not be part > + of the binding and be kept up with Apple's firmware changes in the future. > + > + - It leaves less work for the driver attaching on this binding. Instead the work > + is done upfront in the loader which can be better suited for keeping up with > + Apple's firmware changes. > + > +required: > + - compatible > + - reg > + - '#dma-cells' > + - dma-channels > + - mboxes > + - iommus > + - power-domains > + > +additionalProperties: false > + > +examples: > + - | > + #include <dt-bindings/interrupt-controller/apple-aic.h> > + #include <dt-bindings/interrupt-controller/irq.h> > + > + aic: interrupt-controller { > + interrupt-controller; > + #interrupt-cells = <3>; > + }; > + > + sio_mbox: mbox@36408000 { > + compatible = "apple,t8103-asc-mailbox", "apple,asc-mailbox-v4"; > + reg = <0x36408000 0x4000>; > + interrupt-parent = <&aic>; > + interrupts = <AIC_IRQ 640 IRQ_TYPE_LEVEL_HIGH>, > + <AIC_IRQ 641 IRQ_TYPE_LEVEL_HIGH>, > + <AIC_IRQ 642 IRQ_TYPE_LEVEL_HIGH>, > + <AIC_IRQ 643 IRQ_TYPE_LEVEL_HIGH>; > + interrupt-names = "send-empty", "send-not-empty", > + "recv-empty", "recv-not-empty"; > + #mbox-cells = <0>; > + power-domains = <&ps_sio>; > + }; Drop. Don't need to show providers. > + > + sio: dma-controller@36400000 { > + status = "disabled"; /* To be filled by loader */ Drop. Examples should be enabled so we can validate them. > + compatible = "apple,t8103-sio", "apple,sio"; > + reg = <0x36400000 0x8000>; > + dma-channels = <128>; > + #dma-cells = <1>; > + mboxes = <&sio_mbox>; > + iommus = <&sio_dart 0>; > + power-domains = <&ps_sio_cpu>; > + memory-region = <0x0>; /* To be filled by loader */ > + apple,sio-firmware-params = <0x0>; /* To be filled by loader */ > + }; > -- > 2.33.0
