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coresight: bindings for CPU debug module 

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@linaro.org>
Signed-off-by: Leo Yan <leo.yan@linaro.org>
Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
zero-colors
Leo Yan 2017-06-05 14:15:10 -06:00 committed by Greg Kroah-Hartman
parent a3959c50b0
commit a70fc83d3c
1 changed files with 49 additions and 0 deletions
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49
Documentation/devicetree/bindings/arm/coresight-cpu-debug.txt 100644
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* 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>;
};