Documentation for last level cache controller device tree bindings,
client bindings usage examples.
Signed-off-by: Channagoud Kadabi <ckadabi@xxxxxxxxxxxxxx>
Signed-off-by: Rishabh Bhatnagar <rishabhb@xxxxxxxxxxxxxx>
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+== 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 ==
+
+Properties:
+- 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
+
+Example:
+
+ llcc: qcom,sdm855-llcc@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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