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

Mike Leach
2019-12-06T17:39:51Z

Mathieu, Suzuki,

Fixed per you suggestions.

Thanks

Mike

On Mon, 2 Dec 2019 at 10:43, Suzuki Kuruppassery Poulose
<suzuki.poulose@arm.com> wrote:
>
> 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@linaro.org>
> > ---
> > .../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@linaro.org>
> > + :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@arm.com>

--
Mike Leach
Principal Engineer, ARM Ltd.
Manchester Design Centre. UK