trace/coresight/coresight-ect.rst

1 .. SPDX-License-Identifier: GPL-2.0
4 CoreSight Embedded Cross Trigger (CTI & CTM).
11 --------------------
13 The CoreSight Cross Trigger Interface (CTI) is a hardware device that takes
15 devices and interconnects them via the Cross Trigger Matrix (CTM) to other
21  0 C   0----------->:     :             +======>(other CTI channel IO)
22  0  P  0<-----------:     :             v
24  0000000            : CTI :<=========>*CTM*<====>: CTI :---+
25  #######  in_trigs  :     : (id 0-3)  *****      :::::::   v
26  # ETM #----------->:     :                         ^   #######
27  #     #<-----------:     :                         +---# ETR #
31 channels. When an input trigger becomes active, the attached channel will
32 become active. Any output trigger attached to that channel will also
42 attached CTIs will also be enabled. By default/on power up the CTIs have
43 no programmed trigger/channel attachments, so will not affect the system
46 The hardware trigger connections between CTIs and devices is implementation
50 The hardware trigger signals can also be connected to non-CoreSight devices
60 ---------------------------
72 capable of generating or using trigger signals.::
78 *Key file items are:-*
82    * ``ctmid`` : associated CTM - only relevant if system has multiple CTI+CTM
84    * ``nr_trigger_cons`` : total connections - triggers<N> directories.
87 *Sub-directories:-*
89    * ``channels``: Contains the channel API - CTI main programming interface.
100 Individual trigger connection information. This describes trigger signals for
101 CoreSight and non-CoreSight connections.
107    * ``in_signals`` : input trigger signal indexes used in this connection.
109    * ``out_signals`` : output trigger signals for this connection.
119     0-2
123     0-1
135 'regs' sub-directory elements directly.
148   echo <chan> [<trigger>] > /<device_path>/<operation>
150 where the optional <trigger> is only needed for trigXX_attach | detach
164    * ``trigin_attach, trigout_attach``: Attach a channel to a trigger signal.
165    * ``trigin_detach, trigout_detach``: Detach a channel from a trigger signal.
166    * ``chan_set``: Set the channel - the set state will be propagated around
172      number. CTI gate is enabled for all channels by default at power up. Read
186    * ``trigout_filtered``: Trigger out signals that are prevented from being
189    * ``chan_xtrigs_reset``: Write 1 to clear all channel / trigger programming.
190      Resets device hardware to default state.
193 The example below attaches input trigger index 1 to channel 2, and output
194 trigger index 6 to the same channel. It then examines the state of the
195 channel / trigger connections using the appropriate sysfs attributes.
197 The settings mean that if either input trigger 1, or channel 2 go active then
198 trigger out 6 will go active. We then enable the CTI, and use the software
208    0-1,3