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SubjectRe: [PATCH 1/9] dt-bindings: soc: apple: Add Apple SART
On Mon, Mar 21, 2022 at 05:50:41PM +0100, Sven Peter wrote:
> Apple SoCs such as the M1 come with a simple DMA address filter called
> SART. Unlike a real IOMMU no pagetables can be configured but instead
> DMA transactions can be allowed for up to 16 paddr regions.
>
> Signed-off-by: Sven Peter <sven@svenpeter.dev>
> ---
> .../bindings/soc/apple/apple,sart.yaml | 52 +++++++++++++++++++

Close enough to an IOMMU in terms of its purpose, so put in
bindings/iommu/

> MAINTAINERS | 1 +
> 2 files changed, 53 insertions(+)
> create mode 100644 Documentation/devicetree/bindings/soc/apple/apple,sart.yaml
>
> diff --git a/Documentation/devicetree/bindings/soc/apple/apple,sart.yaml b/Documentation/devicetree/bindings/soc/apple/apple,sart.yaml
> new file mode 100644
> index 000000000000..d8177b3a3fba
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/soc/apple/apple,sart.yaml
> @@ -0,0 +1,52 @@
> +# SPDX-License-Identifier: GPL-2.0 OR BSD-2-Clause
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/soc/apple/apple,sart.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Apple SART DMA address filter
> +
> +maintainers:
> + - Sven Peter <sven@svenpeter.dev>
> +
> +description:
> + Apple SART is a simple address filter for DMA transactions. Regions of
> + physical memory must be added to the SART's allow list before any
> + DMA can target these. Unlike a proper IOMMU no remapping can be done and
> + special support in the consumer driver is required since not all DMA
> + transactions of a single device are subject to SART filtering.
> +
> + SART1 has first been used since at least the A11 (iPhone 8 and iPhone X)
> + and allows 36 bit of physical address space and filter entries with sizes
> + up to 24 bit.
> +
> + SART2, first seen in A14 and M1, allows 36 bit of physical address space
> + and filter entry size up to 36 bit.
> +
> + SART3, first seen in M1 Pro/Max, extends both the address space and filter
> + entry size to 42 bit.
> +
> +properties:
> + compatible:
> + enum:
> + - apple,t6000-sart
> + - apple,t8103-sart
> +
> + reg:
> + maxItems: 1
> +
> + power-domains:
> + maxItems: 1
> +
> +required:
> + - compatible
> + - reg
> +
> +additionalProperties: false
> +
> +examples:
> + - |
> + sart@7bc50000 {
> + compatible = "apple,t8103-sart";
> + reg = <0x7bc50000 0x4000>;
> + };
> diff --git a/MAINTAINERS b/MAINTAINERS
> index cd0f68d4a34a..027c3b4ad61c 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -1774,6 +1774,7 @@ F: Documentation/devicetree/bindings/mailbox/apple,mailbox.yaml
> F: Documentation/devicetree/bindings/pci/apple,pcie.yaml
> F: Documentation/devicetree/bindings/pinctrl/apple,pinctrl.yaml
> F: Documentation/devicetree/bindings/power/apple*
> +F: Documentation/devicetree/bindings/soc/apple/*
> F: Documentation/devicetree/bindings/watchdog/apple,wdt.yaml
> F: arch/arm64/boot/dts/apple/
> F: drivers/i2c/busses/i2c-pasemi-core.c
> --
> 2.25.1
>
>

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