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
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 #
30 The CTI driver enables the programming of the CTI to attach triggers to
34 activating connected output triggers there, unless filtered by the CTI
38 programming registers in the CTI.
41 CoreSight devices on the trace data path. When these devices are enabled the
50 The hardware trigger signals can also be connected to non-CoreSight devices
53 All the CTI devices are associated with a CTM. On many systems there will be a
57 CTI devices that are interconnected via a given CTM.
60 ---------------------------
62 The CTI devices appear on the existing CoreSight bus alongside the other
63 CoreSight devices::
65     >$ ls /sys/bus/coresight/devices
71 can be associated with other CoreSight devices, or other system hardware
74   >$ ls /sys/bus/coresight/devices/etm0/cti_cpu0
78 *Key file items are:-*
79    * ``enable``: enables/disables the CTI. Read to determine current state.
82    * ``ctmid`` : associated CTM - only relevant if system has multiple CTI+CTM
84    * ``nr_trigger_cons`` : total connections - triggers<N> directories.
85    * ``powered`` : Read to determine if the CTI is currently powered.
87 *Sub-directories:-*
89    * ``channels``: Contains the channel API - CTI main programming interface.
90    * ``regs``: Gives access to the raw programmable CTI regs.
91    * ``mgmt``: the standard CoreSight management registers.
92    * ``connections``: Links to connected *CoreSight* devices. The number of
101 CoreSight and non-CoreSight connections.
119     0-2
123     0-1
135 'regs' sub-directory elements directly.
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.
170    * ``chan_gate_enable``: Write operation sets the CTI gate to propagate
172      number. CTI gate is enabled for all channels by default at power up. Read
198 trigger out 6 will go active. We then enable the CTI, and use the software
208    0-1,3