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coresight: trace-id: Add API to dynamically assign Trace ID values

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The existing mechanism to assign Trace ID values to sources is limited
and does not scale for larger multicore / multi trace source systems.

The API introduces functions that reserve IDs based on availabilty
represented by a coresight_trace_id_map structure. This records the
used and free IDs in a bitmap.

CPU bound sources such as ETMs use the coresight_trace_id_get_cpu_id
coresight_trace_id_put_cpu_id pair of functions. The API will record
the ID associated with the CPU. This ensures that the same ID will be
re-used while perf events are active on the CPU. The put_cpu_id function
will pend release of the ID until all perf cs_etm sessions are complete.

For backward compatibility the functions will attempt to use the same
CPU IDs as the legacy system would have used if these are still available.

Non-cpu sources, such as the STM can use coresight_trace_id_get_system_id /
coresight_trace_id_put_system_id.

Signed-off-by: Mike Leach <mike.leach@linaro.org>
[ Fix checkpatch warning in drivers/hwtracing/coresight/coresight-trace-id.c ]
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Link: https://lore.kernel.org/r/20230116124928.5440-2-mike.leach@linaro.org
This commit is contained in:
Mike Leach
2023-01-16 12:49:14 +00:00
committed by Suzuki K Poulose
parent 3f3047493b
commit 338a588e9d
4 changed files with 431 additions and 1 deletions
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10
include/linux/coresight-pmu.h
View File

@@ -10,6 +10,16 @@
#define CORESIGHT_ETM_PMU_NAME "cs_etm"
#define CORESIGHT_ETM_PMU_SEED 0x10
/*
* The legacy Trace ID system based on fixed calculation from the cpu
* number. This has been replaced by drivers using a dynamic allocation
* system - but need to retain the legacy algorithm for backward comparibility
* in certain situations:-
* a) new perf running on older systems that generate the legacy mapping
* b) older tools that may not update at the same time as the kernel.
*/
#define CORESIGHT_LEGACY_CPU_TRACE_ID(cpu) (0x10 + (cpu * 2))
/*
* Below are the definition of bit offsets for perf option, and works as
* arbitrary values for all ETM versions.