On Wed, 11 Dec 2019 at 16:10, Mike Leach <mike.leach@xxxxxxxxxx> 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> > Reviewed-by: Suzuki K Poulose <suzuki.poulose@xxxxxxx> > --- > .../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@xxxxxxxxxx> > + :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:: > + > + >$ ls /sys/bus/coresight/devices > + cti_cpu0 cti_cpu2 cti_sys0 etm0 etm2 funnel0 replicator0 tmc_etr0 > + cti_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.:: > + > + >$ ls /sys/bus/coresight/devices/etm0/cti_cpu0 > + 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:: > + > + >$ ls ./cti_cpu0/triggers0/ > + in_signals in_types name out_signals out_types > + >$ cat ./cti_cpu0/triggers0/name > + cpu0 > + >$ cat ./cti_cpu0/triggers0/out_signals > + 0-2 > + >$ cat ./cti_cpu0/triggers0/out_types > + pe_edbgreq pe_dbgrestart pe_ctiirq > + >$ cat ./cti_cpu0/triggers0/in_signals > + 0-1 > + >$ cat ./cti_cpu0/triggers0/in_types > + 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:: > + > + >$ 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 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 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. > + > + > +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@xxxxxxxxxx> > -- > 2.17.1 >
