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@xxxxxxxxxxxxx> > --- > .../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@xxxxxxxxxxxxx> > + > +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 > >
