linux/drivers/hwtracing/coresight/Kconfig
Leo Yan 2227b7c746 coresight: add support for CPU debug module
Coresight includes debug module and usually the module connects with CPU
debug logic. ARMv8 architecture reference manual (ARM DDI 0487A.k) has
description for related info in "Part H: External Debug".

Chapter H7 "The Sample-based Profiling Extension" introduces several
sampling registers, e.g. we can check program counter value with
combined CPU exception level, secure state, etc. So this is helpful for
analysis CPU lockup scenarios, e.g. if one CPU has run into infinite
loop with IRQ disabled. In this case the CPU cannot switch context and
handle any interrupt (including IPIs), as the result it cannot handle
SMP call for stack dump.

This patch is to enable coresight debug module, so firstly this driver
is to bind apb clock for debug module and this is to ensure the debug
module can be accessed from program or external debugger. And the driver
uses sample-based registers for debug purpose, e.g. when system triggers
panic, the driver will dump program counter and combined context
registers (EDCIDSR, EDVIDSR); by parsing context registers so can
quickly get to know CPU secure state, exception level, etc.

Some of the debug module registers are located in CPU power domain, so
this requires the CPU power domain stays on when access related debug
registers, but the power management for CPU power domain is quite
dependent on SoC integration for power management. For the platforms
which with sane power controller implementations, this driver follows
the method to set EDPRCR to try to pull the CPU out of low power state
and then set 'no power down request' bit so the CPU has no chance to
lose power.

If the SoC has not followed up this design well for power management
controller, the user should use the command line parameter or sysfs
to constrain all or partial idle states to ensure the CPU power
domain is enabled and access coresight CPU debug component safely.

Signed-off-by: Leo Yan <leo.yan@linaro.org>
Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-06-09 11:45:25 +02:00

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#
# Coresight configuration
#
menuconfig CORESIGHT
bool "CoreSight Tracing Support"
select ARM_AMBA
select PERF_EVENTS
help
This framework provides a kernel interface for the CoreSight debug
and trace drivers to register themselves with. It's intended to build
a topological view of the CoreSight components based on a DT
specification and configure the right series of components when a
trace source gets enabled.
if CORESIGHT
config CORESIGHT_LINKS_AND_SINKS
bool "CoreSight Link and Sink drivers"
help
This enables support for CoreSight link and sink drivers that are
responsible for transporting and collecting the trace data
respectively. Link and sinks are dynamically aggregated with a trace
entity at run time to form a complete trace path.
config CORESIGHT_LINK_AND_SINK_TMC
bool "Coresight generic TMC driver"
depends on CORESIGHT_LINKS_AND_SINKS
help
This enables support for the Trace Memory Controller driver.
Depending on its configuration the device can act as a link (embedded
trace router - ETR) or sink (embedded trace FIFO). The driver
complies with the generic implementation of the component without
special enhancement or added features.
config CORESIGHT_SINK_TPIU
bool "Coresight generic TPIU driver"
depends on CORESIGHT_LINKS_AND_SINKS
help
This enables support for the Trace Port Interface Unit driver,
responsible for bridging the gap between the on-chip coresight
components and a trace for bridging the gap between the on-chip
coresight components and a trace port collection engine, typically
connected to an external host for use case capturing more traces than
the on-board coresight memory can handle.
config CORESIGHT_SINK_ETBV10
bool "Coresight ETBv1.0 driver"
depends on CORESIGHT_LINKS_AND_SINKS
help
This enables support for the Embedded Trace Buffer version 1.0 driver
that complies with the generic implementation of the component without
special enhancement or added features.
config CORESIGHT_SOURCE_ETM3X
bool "CoreSight Embedded Trace Macrocell 3.x driver"
depends on !ARM64
select CORESIGHT_LINKS_AND_SINKS
help
This driver provides support for processor ETM3.x and PTM1.x modules,
which allows tracing the instructions that a processor is executing
This is primarily useful for instruction level tracing. Depending
the ETM version data tracing may also be available.
config CORESIGHT_SOURCE_ETM4X
bool "CoreSight Embedded Trace Macrocell 4.x driver"
depends on ARM64
select CORESIGHT_LINKS_AND_SINKS
help
This driver provides support for the ETM4.x tracer module, tracing the
instructions that a processor is executing. This is primarily useful
for instruction level tracing. Depending on the implemented version
data tracing may also be available.
config CORESIGHT_QCOM_REPLICATOR
bool "Qualcomm CoreSight Replicator driver"
depends on CORESIGHT_LINKS_AND_SINKS
help
This enables support for Qualcomm CoreSight link driver. The
programmable ATB replicator sends the ATB trace stream from the
ETB/ETF to the TPIUi and ETR.
config CORESIGHT_STM
bool "CoreSight System Trace Macrocell driver"
depends on (ARM && !(CPU_32v3 || CPU_32v4 || CPU_32v4T)) || ARM64
select CORESIGHT_LINKS_AND_SINKS
select STM
help
This driver provides support for hardware assisted software
instrumentation based tracing. This is primarily used for
logging useful software events or data coming from various entities
in the system, possibly running different OSs
config CORESIGHT_CPU_DEBUG
tristate "CoreSight CPU Debug driver"
depends on ARM || ARM64
depends on DEBUG_FS
help
This driver provides support for coresight debugging module. This
is primarily used to dump sample-based profiling registers when
system triggers panic, the driver will parse context registers so
can quickly get to know program counter (PC), secure state,
exception level, etc. Before use debugging functionality, platform
needs to ensure the clock domain and power domain are enabled
properly, please refer Documentation/trace/coresight-cpu-debug.txt
for detailed description and the example for usage.
endif