According to ARMv8 architecture reference manual (ARM DDI 0487A.k)
Chapter 'Part H: External debug', the CPU can integrate debug module
and it can support self-hosted debug and external debug. Especially
for supporting self-hosted debug, this means the program can access
the debug module from mmio region; and usually the mmio region is
integrated with coresight.
So add document for binding debug component, includes binding to APB
clock; and also need specify the CPU node which the debug module is
dedicated to specific CPU.
Suggested-by: Mike Leach <mike.leach@xxxxxxxxxx>
Reviewed-by: Mathieu Poirier <mathieu.poirier@xxxxxxxxxx>
Reviewed-by: Suzuki K Poulose <suzuki.poulose@xxxxxxx>
Acked-by: Rob Herring <robh@xxxxxxxxxx>
Signed-off-by: Leo Yan <leo.yan@xxxxxxxxxx>
---
.../bindings/arm/coresight-cpu-debug.txt | 49 ++++++++++++++++++++++
1 file changed, 49 insertions(+)
create mode 100644 Documentation/devicetree/bindings/arm/coresight-cpu-debug.txt
diff --git a/Documentation/devicetree/bindings/arm/coresight-cpu-debug.txt b/Documentation/devicetree/bindings/arm/coresight-cpu-debug.txt
new file mode 100644
index 0000000..2982912
--- /dev/null
+++ b/Documentation/devicetree/bindings/arm/coresight-cpu-debug.txt
@@ -0,0 +1,49 @@
+* CoreSight CPU Debug Component:
+
+CoreSight CPU debug component are compliant with the ARMv8 architecture
+reference manual (ARM DDI 0487A.k) Chapter 'Part H: External debug'. The
+external debug module is mainly used for two modes: self-hosted debug and
+external debug, and it can be accessed from mmio region from Coresight
+and eventually the debug module connects with CPU for debugging. And the
+debug module provides sample-based profiling extension, which can be used
+to sample CPU program counter, secure state and exception level, etc;
+usually every CPU has one dedicated debug module to be connected.
+
+Required properties:
+
+- compatible : should be "arm,coresight-cpu-debug"; supplemented with
+ "arm,primecell" since this driver is using the AMBA bus
+ interface.
+
+- reg : physical base address and length of the register set.
+
+- clocks : the clock associated to this component.
+
+- clock-names : the name of the clock referenced by the code. Since we are
+ using the AMBA framework, the name of the clock providing
+ the interconnect should be "apb_pclk" and the clock is
+ mandatory. The interface between the debug logic and the
+ processor core is clocked by the internal CPU clock, so it
+ is enabled with CPU clock by default.
+
+- cpu : the CPU phandle the debug module is affined to. When omitted
+ the module is considered to belong to CPU0.
+
+Optional properties:
+
+- power-domains: a phandle to the debug power domain. We use "power-domains"
+ binding to turn on the debug logic if it has own dedicated
+ power domain and if necessary to use "cpuidle.off=1" or
+ "nohlt" in the kernel command line or sysfs node to
+ constrain idle states to ensure registers in the CPU power
+ domain are accessible.
+
+Example:
+
+ debug@f6590000 {
+ compatible = "arm,coresight-cpu-debug","arm,primecell";
+ reg = <0 0xf6590000 0 0x1000>;
+ clocks = <&sys_ctrl HI6220_DAPB_CLK>;
+ clock-names = "apb_pclk";
+ cpu = <&cpu0>;
+ };
--
2.7.4
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