Introduction of TPDM CMB(Continuous Multi Bit) subunit CMB subunit is responsible for creating a dataset element, and is also optionally responsible for packing it to fit multiple elements on a single ATB transfer if possible in the configuration. The TPDM Core Datapath requests timestamps be stored by the TPDA and then delivering ATB sized data (depending on ATB width and element size, this could be smaller or larger than a dataset element) to the ATB Mast FSM. The CMB makes trace elements in two modes. In �continuous� mode, every valid data cycle creates an element. In �trace on change� mode, when valid data changes on the bus, a trace element is created. In continuous mode, all cycles where this condition is true create trace elements. In trace on change mode, a data element is only when the previously sampled input is different from the current sampled input.
The CMB subunit must be configured prior to enablement. This series adds support for TPDM to configure the configure CMB subunit.
Once this series patches are applied properly, the new tpdm nodes for should be observed at the tpdm path /sys/bus/coresight/devices/tpdm* which supports CMB subunit. e.g. root@qemuarm64:/sys/devices/platform/soc@0/684c000.tpdm/tpdm0# ls -l -rw-r--r-- 1 root root 4096 Jan 1 00:00 cmb_mode drwxr-xr-x 2 root root 0 Jan 1 00:00 cmb_msr drwxr-xr-x 2 root root 0 Jan 1 00:00 cmb_patt drwxr-xr-x 2 root root 0 Jan 1 00:00 cmb_trig_patt -rw-r--r-- 1 root root 4096 Jan 1 00:00 cmb_trig_ts -rw-r--r-- 1 root root 4096 Jan 1 00:00 cmb_ts_all drwxr-xr-x 2 root root 0 Jan 1 00:00 connections drwxr-xr-x 2 root root 0 Jan 1 00:00 dsb_edge drwxr-xr-x 2 root root 0 Jan 1 00:00 dsb_msr drwxr-xr-x 2 root root 0 Jan 1 00:00 dsb_patt drwxr-xr-x 2 root root 0 Jan 1 00:00 dsb_trig_patt -rw-r--r-- 1 root root 4096 Jan 1 00:00 enable_source --w------- 1 root root 4096 Jan 1 00:00 integration_test drwxr-xr-x 2 root root 0 Ja? 1 00:00 power --w------- 1 root root 4096 Jan 1 00:00 reset_dataset lrwxrwxrwx 1 root root 0 Apr 5 2021 subsystem -> ../../../../../bus/coresight -rw-r--r-- 1 root root 4096 Apr 5 2021 uevent -r--r--r-- 1 root root 4096 Jan 1 00:00 waiting_for_supplier
We can use the commands are similar to the below to configure the TPDMs which support CMB subunit. Enable coresight sink first. echo 1 > /sys/bus/coresight/devices/tmc_etf0/enable_sink echo 1 > /sys/bus/coresight/devices/tpdm0/reset_dataset echo 1 > /sys/bus/coresight/devices/tpdm0/cmb_mode echo 1 > /sys/bus/coresight/devices/tpdm0/cmb_patt/enable_ts echo 0xFFFFFFFF > /sys/bus/coresight/devices/tpdm0/cmb_patt/tpmr0 echo 0 > /sys/bus/coresight/devices/tpdm0/cmb_trig_ts echo 0xFFFFFFFF > /sys/bus/coresight/devices/tpdm0/cmb_trig_patt/xpr1 echo 1 > /sys/bus/coresight/devices/tpdm0/enable_source
codelinaro link: https://git.codelinaro.org/clo/linux-kernel/coresight/-/commits/tpdm-cmb-v3
Changes in V3: 1. Add 8-bit support to the description in the TPDM devicetree document. -- Rob Herring 2. Change how the result is produced in "tpdm_read_element_size". -- James Clark 3. Calling "tpdm_clear_element_size" at the beginning of "tpda_enable_port". -- James Clark 4. Use "dsb_esize" and "cmb_esize" to determine whether multiple TPDMs are detected on a TPDA input port in "tpda_get_element_size". -- James Clark 5. Modify the judgment logic in "tpda_enable_port". -- James Clark 6. Add more description of "cmb_mode" to TPDM SysFS document. -- James Clark
Changes in V2: 1. Optimizate and modify this patch series based on the patch series "Add support to configure TPDM CMB subunit". 2. Modify the functions that read the element size of DSB/CMB in TPDA driver.
Tao Zhang (8): dt-bindings: arm: Add support for CMB element size coresight-tpda: Add support to configure CMB element coresight-tpdm: Add CMB dataset support coresight-tpdm: Add support to configure CMB coresight-tpdm: Add pattern registers support for CMB coresight-tpdm: Add timestamp control register support for the CMB dt-bindings: arm: Add support for TPDM CMB MSR register coresight-tpdm: Add msr register support for CMB
.../testing/sysfs-bus-coresight-devices-tpdm | 87 ++++ .../bindings/arm/qcom,coresight-tpdm.yaml | 38 ++ drivers/hwtracing/coresight/coresight-tpda.c | 117 +++--- drivers/hwtracing/coresight/coresight-tpda.h | 6 + drivers/hwtracing/coresight/coresight-tpdm.c | 390 +++++++++++++++++- drivers/hwtracing/coresight/coresight-tpdm.h | 87 ++++ 6 files changed, 673 insertions(+), 52 deletions(-)