Thread (1 message) 1 message, 1 author, 2016-08-23
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[PATCH v5 16/19] Docs: dt: document ARM SMMU generic binding usage

From: Robin Murphy <hidden>
Date: 2016-08-23 19:05:27
Also in: linux-iommu
Subsystem: arm smmu drivers, iommu subsystem, open firmware and flattened device tree bindings, the rest · Maintainers: Will Deacon, Joerg Roedel, Rob Herring, Krzysztof Kozlowski, Conor Dooley, Linus Torvalds

Possibly related (same subject, not in this thread)

Document how the generic "iommus" binding should be used to describe ARM
SMMU stream IDs instead of the old "mmu-masters" binding.

CC: Rob Herring <redacted>
CC: Mark Rutland <redacted>
Signed-off-by: Robin Murphy <redacted>
---
 .../devicetree/bindings/iommu/arm,smmu.txt         | 63 ++++++++++++++++------
 1 file changed, 48 insertions(+), 15 deletions(-)
diff --git a/Documentation/devicetree/bindings/iommu/arm,smmu.txt b/Documentation/devicetree/bindings/iommu/arm,smmu.txt
index 19fe6f2c83f6..e9d447cf3a76 100644
--- a/Documentation/devicetree/bindings/iommu/arm,smmu.txt
+++ b/Documentation/devicetree/bindings/iommu/arm,smmu.txt
@@ -35,12 +35,16 @@ conditions.
                   interrupt per context bank. In the case of a single,
                   combined interrupt, it must be listed multiple times.
 
-- mmu-masters   : A list of phandles to device nodes representing bus
-                  masters for which the SMMU can provide a translation
-                  and their corresponding StreamIDs (see example below).
-                  Each device node linked from this list must have a
-                  "#stream-id-cells" property, indicating the number of
-                  StreamIDs associated with it.
+- #iommu-cells  : See Documentation/devicetree/bindings/iommu/iommu.txt
+                  for details. With a value of 1, each "iommus" entry
+                  represents a distinct stream ID emitted by that device
+                  into the relevant SMMU.
+
+                  SMMUs with stream matching support and complex masters
+                  may use a value of 2, where the second cell represents
+                  an SMR mask to combine with the ID in the first cell.
+                  Care must be taken to ensure the set of matched IDs
+                  does not result in conflicts.
 
 ** System MMU optional properties:
 
@@ -56,9 +60,20 @@ conditions.
                   aliases of secure registers have to be used during
                   SMMU configuration.
 
-Example:
+** Deprecated properties:
 
-        smmu {
+- mmu-masters (deprecated in favour of the generic "iommus" binding) :
+                  A list of phandles to device nodes representing bus
+                  masters for which the SMMU can provide a translation
+                  and their corresponding StreamIDs (see example below).
+                  Each device node linked from this list must have a
+                  "#stream-id-cells" property, indicating the number of
+                  StreamIDs associated with it.
+
+** Examples:
+
+        /* SMMU with stream matching or stream indexing */
+        smmu1: iommu {
                 compatible = "arm,smmu-v1";
                 reg = <0xba5e0000 0x10000>;
                 #global-interrupts = <2>;
@@ -68,11 +83,29 @@ Example:
                              <0 35 4>,
                              <0 36 4>,
                              <0 37 4>;
-
-                /*
-                 * Two DMA controllers, the first with two StreamIDs (0xd01d
-                 * and 0xd01e) and the second with only one (0xd11c).
-                 */
-                mmu-masters = <&dma0 0xd01d 0xd01e>,
-                              <&dma1 0xd11c>;
+                #iommu-cells = <1>;
+        };
+
+        /* device with two stream IDs, 0 and 7 */
+        master1 {
+                iommus = <&smmu1 0>,
+                         <&smmu1 7>;
+        };
+
+
+        /* SMMU with stream matching */
+        smmu2: iommu {
+                ...
+                #iommu-cells = <2>;
+        };
+
+        /* device with stream IDs 0 and 7 */
+        master2 {
+                iommus = <&smmu2 0 0>,
+                         <&smmu2 7 0>;
+        };
+
+        /* device with stream IDs 1, 17, 33 and 49 */
+        master3 {
+                iommus = <&smmu2 1 0x30>;
         };
-- 
2.8.1.dirty

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