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
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
54 single effective CTM (one CTM, or multiple CTMs all interconnected), but it is
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
169    * ``chan_pulse``: Set the channel for a single CoreSight clock cycle.
186    * ``trigout_filtered``: Trigger out signals that are prevented from being
189    * ``chan_xtrigs_reset``: Write 1 to clear all channel / trigger programming.
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