From: Leo Yan Date: Mon, 5 Jun 2017 20:15:10 +0000 (-0600) Subject: coresight: bindings for CPU debug module X-Git-Tag: v4.14-rc1~620^2~52 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=a70fc83d3c50c5e3c69de66d4b13d8a1fbfbbe73;p=platform%2Fkernel%2Flinux-rpi.git 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 Signed-off-by: Leo Yan Reviewed-by: Suzuki K Poulose Acked-by: Rob Herring Signed-off-by: Mathieu Poirier Signed-off-by: Greg Kroah-Hartman --- 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>; + };