[PATCH v2 00/12] coresight: tmc-etr Transparent buffer management

[Suzuki K Poulose]

This series is split of the Coresight ETR perf support patches posted
here [0]. The CATU support and perf backend support will be posted as
separate series for better management and review of the patches.

This series adds the support for TMC ETR Scatter-Gather mode to allow
using physical non-contiguous buffer for holding the trace data. It
also adds a layer to handle the buffer management in a transparent
manner, independent of the underlying mode used by the TMC ETR.
The layer chooses the ETR mode based on different parameters (size,
re-using a set of pages, presence of an SMMU etc.).

Finally we add a sysfs parameter to tune the buffer size for ETR in
sysfs-mode.

During the testing, we found out that if the TMC ETR is not properly
connected to the memory subsystem, the ETR could lock-up the system
while waiting for the "read" transactions to complete in scatter-gather
mode. So, we do not use the mode on a system unless it is safe to do
so. This is specified by a DT property "arm,scatter-gather".

Applies on coreisght-next tree from Mathieu

Changes since previous version [1]:
 - Rebased to Mathieu's coresight-next tree to resolve a conflict.
 - Added tags for DT changes from Rob and Mathieu
 - Split the SG mode backend support patch from the
   ETR-BUF patch.
 - Address other comments from Mathieu

Changes since splitted series [0] :
 - Split the series in [0]
 - Address comments on v2
 - Rename DT property "scatter-gather" to "arm,scatter-gather"
 - Add ETM PID for Cortex-A35, use macros to make the listing easier

[0] - http://lists.infradead.org/pipermail/linux-arm-kernel/2018-May/574875.html
[1] - http://lists.infradead.org/pipermail/linux-arm-kernel/2018-May/579135.html

Suzuki K Poulose (12):
  coresight: ETM: Add support for Arm Cortex-A73 and Cortex-A35
  coresight: tmc: Hide trace buffer handling for file read
  coresight: tmc-etr: Do not clean trace buffer
  coresight: tmc-etr: Disallow perf mode
  coresight: Add helper for inserting synchronization packets
  dts: bindings: Restrict coresight tmc-etr scatter-gather mode
  dts: juno: Add scatter-gather support for all revisions
  coresight: Add generic TMC sg table framework
  coresight: Add support for TMC ETR SG unit
  coresight: tmc-etr: Add transparent buffer management
  coresight: tmc-etr buf: Add TMC scatter gather mode backend
  coresight: tmc: Add configuration support for trace buffer size

 .../ABI/testing/sysfs-bus-coresight-devices-tmc    |    8 +
 .../devicetree/bindings/arm/coresight.txt          |    5 +-
 arch/arm64/boot/dts/arm/juno-base.dtsi             |    1 +
 drivers/hwtracing/coresight/coresight-etb10.c      |   12 +-
 drivers/hwtracing/coresight/coresight-etm4x.c      |   31 +-
 drivers/hwtracing/coresight/coresight-priv.h       |   10 +-
 drivers/hwtracing/coresight/coresight-tmc-etf.c    |   45 +-
 drivers/hwtracing/coresight/coresight-tmc-etr.c    | 1010 ++++++++++++++++++--
 drivers/hwtracing/coresight/coresight-tmc.c        |   83 +-
 drivers/hwtracing/coresight/coresight-tmc.h        |  110 ++-
 drivers/hwtracing/coresight/coresight.c            |    3 +-
 11 files changed, 1144 insertions(+), 174 deletions(-)

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2.7.4