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authorLorenzo Pieralisi <lorenzo.pieralisi@arm.com>2012-07-13 15:55:52 +0100
committerJon Medhurst <tixy@linaro.org>2013-07-01 11:04:52 +0100
commite53b923187b1b07a709ca6e8d76a213b2d91f6e8 (patch)
tree463598daa0de4b23c7d88dacbea3f82d11ff7c50 /Documentation
parent8bb495e3f02401ee6f76d1b1d77f3ac9f079e376 (diff)
downloadvexpress-lsk-e53b923187b1b07a709ca6e8d76a213b2d91f6e8.tar.gz
drivers: bus: add ARM CCI support
On ARM multi-cluster systems coherency between cores running on different clusters is managed by the cache-coherent interconnect (CCI). It allows broadcasting of TLB invalidates and memory barriers and it guarantees cache coherency at system level through snooping of slave interfaces connected to it. This patch enables the basic infrastructure required in Linux to handle and programme the CCI component. Non-local variables used by the CCI management functions called by power down function calls after disabling the cache must be flushed out to main memory in advance, otherwise incoherency of those values may occur if they are sitting in the cache of some other CPU when power down functions execute. Driver code ensures that relevant data structures are flushed from inner and outer caches after the driver probe is completed. CCI slave port resources are linked to set of CPUs through bus masters phandle properties that link the interface resources to masters node in the device tree. Documentation describing the CCI DT bindings is provided with the patch. Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> Signed-off-by: Nicolas Pitre <nicolas.pitre@linaro.org>
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+=======================================================
+ARM CCI cache coherent interconnect binding description
+=======================================================
+
+ARM multi-cluster systems maintain intra-cluster coherency through a
+cache coherent interconnect (CCI) that is capable of monitoring bus
+transactions and manage coherency, TLB invalidations and memory barriers.
+
+It allows snooping and distributed virtual memory message broadcast across
+clusters, through memory mapped interface, with a global control register
+space and multiple sets of interface control registers, one per slave
+interface.
+
+Bindings for the CCI node follow the ePAPR standard, available from:
+
+www.power.org/documentation/epapr-version-1-1/
+
+with the addition of the bindings described in this document which are
+specific to ARM.
+
+* CCI interconnect node
+
+ Description: Describes a CCI cache coherent Interconnect component
+
+ Node name must be "cci".
+ Node's parent must be the root node /, and the address space visible
+ through the CCI interconnect is the same as the one seen from the
+ root node (ie from CPUs perspective as per DT standard).
+ Every CCI node has to define the following properties:
+
+ - compatible
+ Usage: required
+ Value type: <string>
+ Definition: must be set to
+ "arm,cci-400"
+
+ - reg
+ Usage: required
+ Value type: <prop-encoded-array>
+ Definition: A standard property. Specifies base physical
+ address of CCI control registers common to all
+ interfaces.
+
+ - ranges:
+ Usage: required
+ Value type: <prop-encoded-array>
+ Definition: A standard property. Follow rules in the ePAPR for
+ hierarchical bus addressing. CCI interfaces
+ addresses refer to the parent node addressing
+ scheme to declare their register bases.
+
+ CCI interconnect node can define the following child nodes:
+
+ - CCI control interface nodes
+
+ Node name must be "slave-if".
+ Parent node must be CCI interconnect node.
+
+ A CCI control interface node must contain the following
+ properties:
+
+ - compatible
+ Usage: required
+ Value type: <string>
+ Definition: must be set to
+ "arm,cci-400-ctrl-if"
+
+ - interface-type:
+ Usage: required
+ Value type: <string>
+ Definition: must be set to one of {"ace", "ace-lite"}
+ depending on the interface type the node
+ represents.
+
+ - reg:
+ Usage: required
+ Value type: <prop-encoded-array>
+ Definition: the base address and size of the
+ corresponding interface programming
+ registers.
+
+* CCI interconnect bus masters
+
+ Description: masters in the device tree connected to a CCI port
+ (inclusive of CPUs and their cpu nodes).
+
+ A CCI interconnect bus master node must contain the following
+ properties:
+
+ - cci-control-port:
+ Usage: required
+ Value type: <phandle>
+ Definition: a phandle containing the CCI control interface node
+ the master is connected to.
+
+Example:
+
+ cpus {
+ #size-cells = <0>;
+ #address-cells = <1>;
+
+ CPU0: cpu@0 {
+ device_type = "cpu";
+ compatible = "arm,cortex-a15";
+ cci-control-port = <&cci_control1>;
+ reg = <0x0>;
+ };
+
+ CPU1: cpu@1 {
+ device_type = "cpu";
+ compatible = "arm,cortex-a15";
+ cci-control-port = <&cci_control1>;
+ reg = <0x1>;
+ };
+
+ CPU2: cpu@100 {
+ device_type = "cpu";
+ compatible = "arm,cortex-a7";
+ cci-control-port = <&cci_control2>;
+ reg = <0x100>;
+ };
+
+ CPU3: cpu@101 {
+ device_type = "cpu";
+ compatible = "arm,cortex-a7";
+ cci-control-port = <&cci_control2>;
+ reg = <0x101>;
+ };
+
+ };
+
+ dma0: dma@3000000 {
+ compatible = "arm,pl330", "arm,primecell";
+ cci-control-port = <&cci_control0>;
+ reg = <0x0 0x3000000 0x0 0x1000>;
+ interrupts = <10>;
+ #dma-cells = <1>;
+ #dma-channels = <8>;
+ #dma-requests = <32>;
+ };
+
+ cci@2c090000 {
+ compatible = "arm,cci-400";
+ #address-cells = <1>;
+ #size-cells = <1>;
+ reg = <0x0 0x2c090000 0 0x1000>;
+ ranges = <0x0 0x0 0x2c090000 0x6000>;
+
+ cci_control0: slave-if@1000 {
+ compatible = "arm,cci-400-ctrl-if";
+ interface-type = "ace-lite";
+ reg = <0x1000 0x1000>;
+ };
+
+ cci_control1: slave-if@4000 {
+ compatible = "arm,cci-400-ctrl-if";
+ interface-type = "ace";
+ reg = <0x4000 0x1000>;
+ };
+
+ cci_control2: slave-if@5000 {
+ compatible = "arm,cci-400-ctrl-if";
+ interface-type = "ace";
+ reg = <0x5000 0x1000>;
+ };
+ };
+
+This CCI node corresponds to a CCI component whose control registers sits
+at address 0x000000002c090000.
+CCI slave interface @0x000000002c091000 is connected to dma controller dma0.
+CCI slave interface @0x000000002c094000 is connected to CPUs {CPU0, CPU1};
+CCI slave interface @0x000000002c095000 is connected to CPUs {CPU2, CPU3};