diff options
author | Linus Torvalds <torvalds@linux-foundation.org> | 2016-12-13 12:11:01 -0800 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2016-12-13 12:11:01 -0800 |
commit | b78b499a67c3f77aeb6cd0b54724bc38b141255d (patch) | |
tree | 8ebdb5303bb1552577182d9fe4086910b8648d22 /Documentation/trace | |
parent | 098c30557a9a19827240aaadc137e4668157dc6b (diff) | |
parent | 190cc65e912de7e8f7ebddcecfbf55a610281a8c (diff) |
Merge tag 'char-misc-4.10-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc
Pull char/misc driver updates from Greg KH:
"Here's the big char/misc driver patches for 4.10-rc1. Lots of tiny
changes over lots of "minor" driver subsystems, the largest being some
new FPGA drivers. Other than that, a few other new drivers, but no new
driver subsystems added for this kernel cycle, a nice change.
All of these have been in linux-next with no reported issues"
* tag 'char-misc-4.10-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc: (107 commits)
uio-hv-generic: store physical addresses instead of virtual
Tools: hv: kvp: configurable external scripts path
uio-hv-generic: new userspace i/o driver for VMBus
vmbus: add support for dynamic device id's
hv: change clockevents unbind tactics
hv: acquire vmbus_connection.channel_mutex in vmbus_free_channels()
hyperv: Fix spelling of HV_UNKOWN
mei: bus: enable non-blocking RX
mei: fix the back to back interrupt handling
mei: synchronize irq before initiating a reset.
VME: Remove shutdown entry from vme_driver
auxdisplay: ht16k33: select framebuffer helper modules
MAINTAINERS: add git url for fpga
fpga: Clarify how write_init works streaming modes
fpga zynq: Fix incorrect ISR state on bootup
fpga zynq: Remove priv->dev
fpga zynq: Add missing \n to messages
fpga: Add COMPILE_TEST to all drivers
uio: pruss: add clk_disable()
char/pcmcia: add some error checking in scr24x_read()
...
Diffstat (limited to 'Documentation/trace')
-rw-r--r-- | Documentation/trace/intel_th.txt | 22 | ||||
-rw-r--r-- | Documentation/trace/stm.txt | 37 |
2 files changed, 56 insertions, 3 deletions
diff --git a/Documentation/trace/intel_th.txt b/Documentation/trace/intel_th.txt index f7fc5ba5df8d..f92070e7dde0 100644 --- a/Documentation/trace/intel_th.txt +++ b/Documentation/trace/intel_th.txt @@ -97,3 +97,25 @@ $ echo 0 > /sys/bus/intel_th/devices/0-msc0/active # and now you can collect the trace from the device node: $ cat /dev/intel_th0/msc0 > my_stp_trace + +Host Debugger Mode +================== + +It is possible to configure the Trace Hub and control its trace +capture from a remote debug host, which should be connected via one of +the hardware debugging interfaces, which will then be used to both +control Intel Trace Hub and transfer its trace data to the debug host. + +The driver needs to be told that such an arrangement is taking place +so that it does not touch any capture/port configuration and avoids +conflicting with the debug host's configuration accesses. The only +activity that the driver will perform in this mode is collecting +software traces to the Software Trace Hub (an stm class device). The +user is still responsible for setting up adequate master/channel +mappings that the decoder on the receiving end would recognize. + +In order to enable the host mode, set the 'host_mode' parameter of the +'intel_th' kernel module to 'y'. None of the virtual output devices +will show up on the intel_th bus. Also, trace configuration and +capture controlling attribute groups of the 'gth' device will not be +exposed. The 'sth' device will operate as usual. diff --git a/Documentation/trace/stm.txt b/Documentation/trace/stm.txt index ea035f9dbfd7..11cff47eecce 100644 --- a/Documentation/trace/stm.txt +++ b/Documentation/trace/stm.txt @@ -69,12 +69,43 @@ stm device's channel mmio region is 64 bytes and hardware page size is width==64, you should be able to mmap() one page on this file descriptor and obtain direct access to an mmio region for 64 channels. +Examples of STM devices are Intel(R) Trace Hub [1] and Coresight STM +[2]. + +stm_source +========== + For kernel-based trace sources, there is "stm_source" device class. Devices of this class can be connected and disconnected to/from -stm devices at runtime via a sysfs attribute. +stm devices at runtime via a sysfs attribute called "stm_source_link" +by writing the name of the desired stm device there, for example: -Examples of STM devices are Intel(R) Trace Hub [1] and Coresight STM -[2]. +$ echo dummy_stm.0 > /sys/class/stm_source/console/stm_source_link + +For examples on how to use stm_source interface in the kernel, refer +to stm_console or stm_heartbeat drivers. + +Each stm_source device will need to assume a master and a range of +channels, depending on how many channels it requires. These are +allocated for the device according to the policy configuration. If +there's a node in the root of the policy directory that matches the +stm_source device's name (for example, "console"), this node will be +used to allocate master and channel numbers. If there's no such policy +node, the stm core will pick the first contiguous chunk of channels +within the first available master. Note that the node must exist +before the stm_source device is connected to its stm device. + +stm_console +=========== + +One implementation of this interface also used in the example above is +the "stm_console" driver, which basically provides a one-way console +for kernel messages over an stm device. + +To configure the master/channel pair that will be assigned to this +console in the STP stream, create a "console" policy entry (see the +beginning of this text on how to do that). When initialized, it will +consume one channel. [1] https://software.intel.com/sites/default/files/managed/d3/3c/intel-th-developer-manual.pdf [2] http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.ddi0444b/index.html |