[PATCH v5 1/9] coresight: bindings for CPU debug module

Leo Yan leo.yan at linaro.org
Sat Mar 25 11:23:09 PDT 2017

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 at linaro.org>
Reviewed-by: Mathieu Poirier <mathieu.poirier at linaro.org>
Signed-off-by: Leo Yan <leo.yan at linaro.org>
 .../bindings/arm/coresight-cpu-debug.txt           | 48 ++++++++++++++++++++++
 1 file changed, 48 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..7ef3824
--- /dev/null
+++ b/Documentation/devicetree/bindings/arm/coresight-cpu-debug.txt
@@ -0,0 +1,48 @@
+* 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 "idle_constraint" in
+		 kernel command line or debugfs node to constrain idle states
+		 to ensure registers in the CPU power domain are accessible.
+	debug at 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>;
+	};

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