[PATCH 1/9] dt-bindings: soc: apple: Add Apple SART

[Sven Peter <sven@svenpeter.dev>]

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 +++++++++++++++++++
 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