From patchwork Mon Aug 28 17:00:12 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: =?utf-8?q?Martin_Povi=C5=A1er?= X-Patchwork-Id: 717961 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id F3051C83F11 for ; Mon, 28 Aug 2023 17:01:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232766AbjH1RBB (ORCPT ); Mon, 28 Aug 2023 13:01:01 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34332 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232725AbjH1RAb (ORCPT ); Mon, 28 Aug 2023 13:00:31 -0400 Received: from hutie.ust.cz (hutie.ust.cz [IPv6:2a03:3b40:fe:f0::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 64C81AC; Mon, 28 Aug 2023 10:00:19 -0700 (PDT) From: =?utf-8?q?Martin_Povi=C5=A1er?= DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=cutebit.org; s=mail; t=1693242017; bh=WechP6q8K5T0IYjDZDXT+ltodAKJ4iHlXIyKTYpv1qs=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=poxjIxKMerGH8BxR7UauZN+AqNEf+YLya1J38BBd+y0tWbZL1FSMAjxgiZQWq48pJ U8VJW5W9pgt9aFB4Pqp37q6cDXyMg9gCb3MsEb7UHv6eMUFuo2KC+Gc5Ntn834bQpx yTIgZ+FM+l/8va99cJwPZktCCAU/cwLDW1vecDPw= To: =?utf-8?q?Martin_Povi=C5=A1er?= , Vinod Koul , Rob Herring , Krzysztof Kozlowski , Conor Dooley Cc: asahi@lists.linux.dev, dmaengine@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, Rob Herring Subject: [PATCH v2 1/2] dt-bindings: dma: apple,sio: Add schema Date: Mon, 28 Aug 2023 19:00:12 +0200 Message-Id: <20230828170013.75820-2-povik+lin@cutebit.org> In-Reply-To: <20230828170013.75820-1-povik+lin@cutebit.org> References: <20230828170013.75820-1-povik+lin@cutebit.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: devicetree@vger.kernel.org Describe the SIO coprocessor which serves as pretend DMA controller on recent Apple platforms. Reviewed-by: Rob Herring Signed-off-by: Martin Povišer --- This patch saw RFC rounds not counted in the series being v2. https://lore.kernel.org/asahi/167693643966.613996.10372170526471864080.robh@kernel.org .../devicetree/bindings/dma/apple,sio.yaml | 111 ++++++++++++++++++ 1 file changed, 111 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..0e3780ad9dd7 --- /dev/null +++ b/Documentation/devicetree/bindings/dma/apple,sio.yaml @@ -0,0 +1,111 @@ +# 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: + 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 + +allOf: + - $ref: dma-controller.yaml# + +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: + minItems: 2 + maxItems: 8 + 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 + + 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 point into the reserved memory + regions (in device address space). + + 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: + - | + sio: dma-controller@36400000 { + 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 = <&sio_text>, <&sio_data>, + <&sio_auxdata1>, <&sio_auxdata2>; /* Filled by loader */ + apple,sio-firmware-params = <0xb 0x10>, <0xc 0x1b80>, <0xf 0x14>, + <0x10 0x1e000>, <0x30d 0x34>, <0x30e 0x4000>, + <0x1a 0x38>, <0x1b 0x50>; /* Filled by loader */ + };