Re: [PATCH v5 13/14] docs: coresight: Update documentation for CoreSight to cover CTI.

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On 19/11/2019 23:19, Mike Leach wrote:
Add new document covering CTI / CTM usage in CoreSight.

Add section in coresight.rst introducing CTI and CTM modules with link
to new document.

Signed-off-by: Mike Leach <mike.leach@xxxxxxxxxx>
---
  .../trace/coresight/coresight-ect.rst         | 200 ++++++++++++++++++
  Documentation/trace/coresight/coresight.rst   |  13 ++
  2 files changed, 213 insertions(+)
  create mode 100644 Documentation/trace/coresight/coresight-ect.rst

diff --git a/Documentation/trace/coresight/coresight-ect.rst b/Documentation/trace/coresight/coresight-ect.rst
new file mode 100644
index 000000000000..6448cf910f20
--- /dev/null
+++ b/Documentation/trace/coresight/coresight-ect.rst
@@ -0,0 +1,200 @@
+=============================================
+CoreSight Embedded Cross Trigger (CTI & CTM).
+=============================================
+
+    :Author:   Mike Leach <mike.leach@xxxxxxxxxx>
+    :Date:     November 2019
+

...


+
+Channels API Directory
+~~~~~~~~~~~~~~~~~~~~~~
+
+This provides an easy way to attach triggers to channels, without needing
+the multiple register operations that are required if manipluating the
+'regs' sub-dir elements directly.
+
+A number of files provide this API::
+
+   >$ ls ./cti_sys0/channels/
+   chan_clear         chan_inuse         chan_xtrigs_view      trigin_detach
+   chan_free          chan_pulse         chan_xtrigs_view_sel  trigout_attach
+   chan_gate_disable  chan_set           trig_filter_enable    trigout_detach
+   chan_gate_enable   chan_xtrigs_reset  trigin_attach         trigout_filtered
+
+Most access to these elements take the form::
+
+  echo <chan> [<trigger>] > /<device_path>/<operation>
+
+where the optional <trigger> is only needed for trigXX_attach | detach
+operations.
+
+e.g.::
+
+   >$ echo 0 1 > ./cti_sys0/channels/trigout_attach
+   >$ echo 0 > ./cti_sys0/channels/chan_set
+
+Attaches trigout(1) to channel(0), then activates channel(0) generating a
+set state on cti_sys0.trigout(1)
+
+
+*API operations*
+
+   * ``trigin_attach, trigout_attach``: Attach a channel to a trigger signal.
+   * ``trigin_detach, trigout_detach``: Detach a channel from a trigger signal.
+   * ``chan_set``: Set the channel - the set state will be propogated around
+     the CTM to other connected devices.
+   * ``chan_clear``: Clear the channel.
+   * ``chan_pulse``: Set the channel for a single CoreSight clock cycle.
+   * ``chan_gate_enable``: Write operation sets the CTI gate to propagate
+     (enable) the channel to other devices. This operation takes a channel
+     number. CTI gate is enabled for all channels by default at power up. Read
+     to list the currently enabled channels on the gate.
+   * ``chan_gate_disable``: Write channel number to disable gate for that
+     channel.
+   * ``chan_inuse``: Show the current channels attached to any signal
+   * ``chan_free``: Show channels with no attached signals.
+   * ``chan_xtrig_view``: write a channel number to select a channel to view,
+     read to show the cross triggers programmed for the selected channel.
+   * ``trig_filter_enable``: Defaults to enabled, disable to allow potentially
+     dangerous output signals to be set.
+   * ``trigout_filtered``: Trigger out signals that are prevented from being
+     set if filtering ``trig_filter_enable`` is enabled. One use is to prevent
+     accidental ``EDBGREQ`` signals stopping a core.
+   * ``chan_xtrigs_reset``: Write 1 to clear all channel / trigger programming.
+     Resets device hardware to default state.
+
+e.g.::
+
+   .../cti_sys0/channels# echo 2 1 > trigin_attach
+   .../cti_sys0/channels# echo 2 6 > trigout_attach

minor nit: It may be a good idea to add a comment to describe what you
are doing with the above operations, to avoid looking up and mapping it
for someone looking it up. I am not too keen, but it is definitely
helpful.

+   .../cti_sys0/channels# cat chan_free
+   0-1,3
+   .../cti_sys0/channels# cat chan_inuse
+   2
+   .../cti_sys0/channels# echo 2 > chan_xtrigs_view
+   .../cti_sys0/channels# cat chan_xtrigs_view
+   [2] IN: 1 OUT: 6
+   .../cti_sys0/# echo 1 > enable
+   .../cti_sys0/channels# echo 2 > chan_set
+   .../cti_sys0/channels# cat ../regs/choutstatus
+   0x4
+   .../cti_sys0/channels# cat ../regs/trigoutstatus
+   0x40
+   .../cti_sys0/channels# echo 2 > chan_clear

+   .../cti_sys0/channels# cat ../regs/trigoutstatus
+   0x0
+   .../cti_sys0/channels# cat ../regs/trigoutstatus
+   0x0

nit: duplicate lines ?

Otherwise:

Reviewed-by: Suzuki K Poulose <suzuki.poulose@xxxxxxx>



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