Add binding document for TI use of mmio-sram driver for purposes like
mapping the region as executable or reserving space needed by secure
silicon.
Signed-off-by: Dave Gerlach <d-gerlach@xxxxxx>
---
Documentation/devicetree/bindings/sram/ti-sram.txt | 47 ++++++++++++++++++++++
1 file changed, 47 insertions(+)
create mode 100644 Documentation/devicetree/bindings/sram/ti-sram.txt
diff --git a/Documentation/devicetree/bindings/sram/ti-sram.txt b/Documentation/devicetree/bindings/sram/ti-sram.txt
new file mode 100644
index 000000000000..68c4b733c78c
--- /dev/null
+++ b/Documentation/devicetree/bindings/sram/ti-sram.txt
@@ -0,0 +1,47 @@
+TI SRAM Node:
+-------------
+
+Many TI SoC's rely on SRAM for running low-level PM code as part of the
+suspend or cpuidle path. Because of this, regions in sram must be mapped
+as "memory-exec" or "memory-exec-nocache" in order for the region to be
+executable.
+
+Optional sub-node
+-----------------
+Some TI SoCs have secure variants that require a certain portion of
+the SRAM to be reserved for use by secure software. This can be
+marked in the parent SRAM node with a subnode as described in
+Documentation/devicetree/bindings/sram/sram.txt. This node can be
+added in two ways:
+
+- From board dts files for secure platforms to avoid adding it
+ for all SoC variants with a fixed size defined.
+- As a dummy node in the .dtsi sram node with any size that will be
+ modified by a bootloader to the correct size needed.
+
+Sub-node properties:
+- compatible : should be "ti,secure-sram"
+
+The rest of the properties should follow the generic mmio-sram discription
+found in Documentation/devicetree/bindings/sram/sram.txt
+
+Example:
+ /* In parent SoC .dtsi */
+ ocmcram: ocmcram@40200000 {
+ compatible = "mmio-sram";
+ reg = <0x40200000 0x10000>; /* 64k */
+ memory-exec-nocache;
+ ranges = <0x0 0x40200000 0x10000>;
+
+ #address-cells = <1>;
+ #size-cells = <1>;
+
+ };
+
+ /* In board .dts where secure silicon is present */
+ &ocmcram {
+ sram-hs@0 {
+ compatible = "ti,secure-ram";
+ reg = <0x0 0xC000>;
+ };
+ };
--
2.7.3
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