[PATCH v2 1/2] Documentation: Documentation for qcom, llcc

Rishabh Bhatnagar rishabhb at codeaurora.org
Sat Mar 24 18:29:15 PDT 2018

Documentation for last level cache controller device tree bindings,
client bindings usage examples.

Change-Id: Ic2d6d6154ab8269cfce6828e9f2250320a0572e8
Signed-off-by: Channagoud Kadabi <ckadabi at codeaurora.org>
Signed-off-by: Rishabh Bhatnagar <rishabhb at codeaurora.org>
 .../devicetree/bindings/arm/msm/qcom,llcc.txt      | 70 ++++++++++++++++++++++
 1 file changed, 70 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/arm/msm/qcom,llcc.txt

diff --git a/Documentation/devicetree/bindings/arm/msm/qcom,llcc.txt b/Documentation/devicetree/bindings/arm/msm/qcom,llcc.txt
new file mode 100644
index 0000000..ceb20a4
--- /dev/null
+++ b/Documentation/devicetree/bindings/arm/msm/qcom,llcc.txt
@@ -0,0 +1,70 @@
+== Introduction==
+LLCC (Last Level Cache Controller) driver is implemented as a platform device.
+The driver Programs the SCT (system configuration table). The SCT programming 
+divides the system cache into slices. Each slice is assigned an ID A.K.A 
+SCID(Sub-cache ID).				
+HW modules that are designated to use the system cache are known as clients.	
+Each client must also be represented as a node in the device tree just like	
+any other hw module.		
+One client can have multiple SCID's assigned meaning each client could get		
+multiple slices in the cache. Client can use the slices for various pre-defined
+usecases. Each client defines a set of names for these usecases in its		
+device tree binding.				
+Client makes a request to LLCC device to get cache-slices properties for each	
+of its usecase. Client gets the information like cache slice ID and size of the
+cache slice.
+== llcc device ==
+- compatible:
+	 Usage: required
+	 Value type: <string>
+	 Definition: must be "qcom,sdm855-llcc"
+- reg:
+	 Usage: required
+	 Value Type: <prop-encoded-array>
+	 Definition: must be addresses and sizes of the LLCC registers
+- #cache-cells:
+	 Usage: required
+	 Value Type: <u32>
+	 Definition: Number of cache cells, must be 1
+- max-slices:
+	 usage: required
+	 Value Type: <u32>
+	 Definition: Number of cache slices supported by hardware
+	llcc: qcom,sdm855-llcc at 01100000 {
+		compatible = "qcom,sdm845-llcc";
+		reg = <0x01100000 0x250000>;
+		#cache-cells = <1>;
+		max-slices = <32>;
+	};
+== Client ==
+Required properties:
+- cache-slice-names:
+	 Usage: required
+	 Value type: <stringlist>
+	 Definition: A set of names that identify the usecase names of a client that
+			uses cache slice. These strings are used to look up the cache slice
+		    entries by name.
+- cache-slices:
+	 Usage: required
+	 Value type: <prop-encoded-array>
+	 Definition: The tuple has phandle to llcc device as the first argument and 
+			the second argument is the usecase id of the client.
+For Example:
+	 venus {
+	 	cache-slice-names = "vidsc0", "vidsc1";
+	 	cache-slices = <&llcc 2>, <&llcc 3>;
+	 };
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