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ARM CCI cache coherent interconnect binding description
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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 contain one of the following:
"arm,cci-400"
"arm,cci-500"
"arm,cci-550"
- reg
Usage: required
Value type: Integer cells. A register entry, expressed as a pair
of cells, containing base and size.
Definition: A standard property. Specifies base physical
address of CCI control registers common to all
interfaces.
- ranges:
Usage: required
Value type: Integer cells. An array of range entries, expressed
as a tuple of cells, containing child address,
parent address and the size of the region in the
child address space.
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: Integer cells. A register entry, expressed
as a pair of cells, containing base and
size.
Definition: the base address and size of the
corresponding interface programming
registers.
- CCI PMU node
Parent node must be CCI interconnect node.
A CCI pmu node must contain the following properties:
- compatible
Usage: required
Value type: <string>
Definition: Must contain one of:
"arm,cci-400-pmu,r0"
"arm,cci-400-pmu,r1"
"arm,cci-400-pmu" - DEPRECATED, permitted only where OS has
secure access to CCI registers
"arm,cci-500-pmu,r0"
"arm,cci-550-pmu,r0"
- reg:
Usage: required
Value type: Integer cells. A register entry, expressed
as a pair of cells, containing base and
size.
Definition: the base address and size of the
corresponding interface programming
registers.
- interrupts:
Usage: required
Value type: Integer cells. Array of interrupt specifier
entries, as defined in
../interrupt-controller/interrupts.txt.
Definition: list of counter overflow interrupts, one per
counter. The interrupts must be specified
starting with the cycle counter overflow
interrupt, followed by counter0 overflow
interrupt, counter1 overflow interrupt,...
,counterN overflow interrupt.
The CCI PMU has an interrupt signal for each
counter. The number of interrupts must be
equal to the number of counters.
* 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 0x10000>;
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>;
};
pmu@9000 {
compatible = "arm,cci-400-pmu";
reg = <0x9000 0x5000>;
interrupts = <0 101 4>,
<0 102 4>,
<0 103 4>,
<0 104 4>,
<0 105 4>;
};
};
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};