227 lines
9.3 KiB
ReStructuredText
227 lines
9.3 KiB
ReStructuredText
|
.. SPDX-License-Identifier: GPL-2.0
|
||
|
|
|
||
|
|
=============================================
|
||
|
|
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::
|
||
|
|
|
||
|
|
>$ 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 powered regs
|
||
|
|
connections subsystem triggers0 triggers1 uevent
|
||
|
|
|
||
|
|
*Key file items are:-*
|
||
|
|
* ``enable``: enables/disables the CTI. Read to determine current state.
|
||
|
|
If this shows as enabled (1), but ``powered`` shows unpowered (0), then
|
||
|
|
the enable indicates a request to enabled when the device is powered.
|
||
|
|
* ``ctmid`` : associated CTM - only relevant if system has multiple CTI+CTM
|
||
|
|
clusters that are not interconnected.
|
||
|
|
* ``nr_trigger_cons`` : total connections - triggers<N> directories.
|
||
|
|
* ``powered`` : Read to determine if the CTI is currently powered.
|
||
|
|
|
||
|
|
*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.
|
||
|
|
* ``connections``: Links to connected *CoreSight* devices. The number of
|
||
|
|
links can be 0 to ``nr_trigger_cons``. Actual number given by ``nr_links``
|
||
|
|
in this directory.
|
||
|
|
|
||
|
|
|
||
|
|
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-directory elements directly.
|
||
|
|
|
||
|
|
A number of files provide this API::
|
||
|
|
|
||
|
|
>$ ls ./cti_sys0/channels/
|
||
|
|
chan_clear chan_inuse chan_xtrigs_out trigin_attach
|
||
|
|
chan_free chan_pulse chan_xtrigs_reset trigin_detach
|
||
|
|
chan_gate_disable chan_set chan_xtrigs_sel trigout_attach
|
||
|
|
chan_gate_enable chan_xtrigs_in trig_filter_enable trigout_detach
|
||
|
|
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_xtrigs_sel``: write a channel number to select a channel to view,
|
||
|
|
read to show the selected channel number.
|
||
|
|
* ``chan_xtrigs_in``: Read to show the input triggers attached to
|
||
|
|
the selected view channel.
|
||
|
|
* ``chan_xtrigs_out``:Read to show the output triggers attached to
|
||
|
|
the selected view 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_sel
|
||
|
|
.../cti_sys0/channels# cat chan_xtrigs_trigin
|
||
|
|
1
|
||
|
|
.../cti_sys0/channels# cat chan_xtrigs_trigout
|
||
|
|
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
|