On Wed, 11 Dec 2019 at 16:10, Mike Leach mike.leach@linaro.org 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 Reviewed-by: Suzuki K Poulose suzuki.poulose@arm.com
.../trace/coresight/coresight-ect.rst | 211 ++++++++++++++++++ Documentation/trace/coresight/coresight.rst | 13 ++ 2 files changed, 224 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..3e06588f24fa --- /dev/null +++ b/Documentation/trace/coresight/coresight-ect.rst @@ -0,0 +1,211 @@ +============================================= +CoreSight Embedded Cross Trigger (CTI & CTM). +=============================================
- :Author: Mike Leach mike.leach@linaro.org
- :Date: November 2019
+Hardware Description +--------------------
+The CoreSight Cross Trigger Interface (CTI) is a hardware device that takes +individual input and output hardware signals known as triggers to and from +devices and interconnects them via the Cross Trigger Matrix (CTM) to other +devices via numbered channels, in order to propagate events between devices.
+e.g.::
- 0000000 in_trigs :::::::
- 0 C 0----------->: : +======>(other CTI channel IO)
- 0 P 0<-----------: : v
- 0 U 0 out_trigs : : Channels ***** :::::::
- 0000000 : CTI :<=========>*CTM*<====>: CTI :---+
- ####### in_trigs : : (id 0-3) ***** ::::::: v
- # ETM #----------->: : ^ #######
- # #<-----------: : +---# ETR #
- ####### out_trigs ::::::: #######
+The CTI driver enables the programming of the CTI to attach triggers to +channels. When an input trigger becomes active, the attached channel will +become active. Any output trigger attached to that channel will also +become active. The active channel is propagated to other CTIs via the CTM, +activating connected output triggers there, unless filtered by the CTI +channel gate.
+It is also possible to activate a channel using system software directly +programming registers in the CTI.
+The CTIs are registered by the system to be associated with CPUs and/or other +CoreSight devices on the trace data path. When these devices are enabled the +attached CTIs will also be enabled. By default/on power up the CTIs have +no programmed trigger/channel attachments, so will not affect the system +until explicitly programmed.
+The hardware trigger connections between CTIs and devices is implementation +defined, unless the CPU/ETM combination is a v8 architecture, in which case +the connections have an architecturally defined standard layout.
+The hardware trigger signals can also be connected to non-CoreSight devices +(e.g. UART), or be propagated off chip as hardware IO lines.
+All the CTI devices are associated with a CTM. On many systems there will be a +single effective CTM (one CTM, or multiple CTMs all interconnected), but it is +possible that systems can have nets of CTIs+CTM that are not interconnected by +a CTM to each other. On these systems a CTM index is declared to associate +CTI devices that are interconnected via a given CTM.
+Sysfs files and directories +---------------------------
+The CTI devices appear on the existing CoreSight bus alongside the other +CoreSight devices::
cti_cpu0 cti_cpu2 cti_sys0 etm0 etm2 funnel0 replicator0 tmc_etr0cti_cpu1 cti_cpu3 cti_sys1 etm1 etm3 funnel1 tmc_etf0 tpiu0+The ``cti_cpu<N>`` named CTIs are associated with a CPU, and any ETM used by +that core. the ``cti_sys<N>`` CTIs are general system infrastructure CTIs that +can be associated with other CoreSight devices, or other system hardware +capable of generating or using trigger signals.::
- channels ctmid enable nr_trigger_cons mgmt power regs subsystem
- triggers0 triggers1 uevent
+*Key file items are:-*
- ``enable``: enables/disables the CTI.
- ``ctmid`` : associated CTM - only relevant if system has multiple CTI+CTM
clusters that are not interconnected.
- ``nr_trigger_cons`` : total connections - triggers<N> directories.
+*Sub-directories:-*
- ``triggers<N>``: contains list of triggers for an individual connection.
- ``channels``: Contains the channel API - CTI main programming interface.
- ``regs``: Gives access to the raw programmable CTI regs.
- ``mgmt``: the standard CoreSight management registers.
+triggers<N> directories +~~~~~~~~~~~~~~~~~~~~~~~
+Individual trigger connection information. This describes trigger signals for +CoreSight and non-CoreSight connections.
+Each triggers directory has a set of parameters describing the triggers for +the connection.
- ``name`` : name of connection
- ``in_signals`` : input trigger signal indexes used in this connection.
- ``in_types`` : functional types for in signals.
- ``out_signals`` : output trigger signals for this connection.
- ``out_types`` : functional types for out signals.
+e.g::
- in_signals in_types name out_signals out_types
- cpu0
- 0-2
- pe_edbgreq pe_dbgrestart pe_ctiirq
- 0-1
- pe_dbgtrigger pe_pmuirq
+If a connection has zero signals in either the 'in' or 'out' triggers then +those parameters will be omitted.
+Channels API Directory +~~~~~~~~~~~~~~~~~~~~~~
+This provides an easy way to attach triggers to channels, without needing +the multiple register operations that are required if manipulating the +'regs' sub-dir elements directly.
+A number of files provide this API::
- 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.::
+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 propagated 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 channelnumber. CTI gate is enabled for all channels by default at power up. Readto 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 preventaccidental ``EDBGREQ`` signals stopping a core.
- ``chan_xtrigs_reset``: Write 1 to clear all channel / trigger programming.
Resets device hardware to default state.+The example below attaches input trigger index 1 to channel 2, and output +trigger index 6 to the same channel. It then examines the state of the +channel / trigger connections using the appropriate sysfs attributes.
+The settings mean that if either input trigger 1, or channel 2 go active then +trigger out 6 will go active. We then enable the CTI, and use the software +channel control to activate channel 2. We see the active channel on the +``choutstatus`` register and the active signal on the ``trigoutstatus`` +register. Finally clearing the channel removes this.
+e.g.::
- .../cti_sys0/channels# echo 2 1 > trigin_attach
- .../cti_sys0/channels# echo 2 6 > trigout_attach
- .../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/choutstatus
- 0x0
diff --git a/Documentation/trace/coresight/coresight.rst b/Documentation/trace/coresight/coresight.rst index a566719f8e7e..108600ee1e12 100644 --- a/Documentation/trace/coresight/coresight.rst +++ b/Documentation/trace/coresight/coresight.rst @@ -491,8 +491,21 @@ interface provided for that purpose by the generic STM API::
Details on how to use the generic STM API can be found here:- :doc:`../stm` [#second]_.
+The CTI & CTM Modules +---------------------
+The CTI (Cross Trigger Interface) provides a set of trigger signals between +individual CTIs and components, and can propagate these between all CTIs via +channels on the CTM (Cross Trigger Matrix).
+A separate documentation file is provided to explain the use of these devices. +(:doc:`coresight-ect`) [#fourth]_.
.. [#first] Documentation/ABI/testing/sysfs-bus-coresight-devices-stm
.. [#second] Documentation/trace/stm.rst
.. [#third] https://github.com/Linaro/perf-opencsd
+.. [#fourth] Documentation/trace/coresight/coresight-ect.rst
Reviewed-by: Mathieu Poirier mathieu.poirier@linaro.org
-- 2.17.1