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Message-ID: <f41fbf20-7e18-4d4c-aa4c-3a363c3cf56d@quicinc.com>
Date: Fri, 27 Jun 2025 14:28:44 +0800
From: Songwei Chai <quic_songchai@...cinc.com>
To: Suzuki K Poulose <suzuki.poulose@....com>,
Mike Leach
<mike.leach@...aro.org>, James Clark <james.clark@....com>,
Alexander
Shishkin <alexander.shishkin@...ux.intel.com>,
Andy Gross
<agross@...nel.org>,
Bjorn Andersson <andersson@...nel.org>,
Rob Herring
<robh+dt@...nel.org>,
Krzysztof Kozlowski <krzk+dt@...nel.org>,
Conor Dooley
<conor+dt@...nel.org>
CC: <linux-kernel@...r.kernel.org>, <coresight@...ts.linaro.org>,
<linux-arm-kernel@...ts.infradead.org>,
<linux-arm-msm@...r.kernel.org>, <devicetree@...r.kernel.org>
Subject: Re: [PATCH v5 0/7] Provides support for Trigger Generation Unit
Hope this message finds you well.
Just following up on my previous message - I'd greatly appreciate your
response when you have a moment.
Looking forward to hearing from you. :-)
BRs,
Songwei
On 5/29/2025 4:19 PM, Songwei Chai wrote:
> Provide support for the TGU (Trigger Generation Unit), which can be
> utilized to sense a plurality of signals and create a trigger into
> the CTI or generate interrupts to processors once the input signal
> meets the conditions. We can treat the TGU’s workflow as a flowsheet,
> it has some “steps” regions for customization. In each step region,
> we can set the signals that we want with priority in priority_group, set
> the conditions in each step via condition_decode, and set the resultant
> action by condition_select. Meanwhile, some TGUs (not all) also provide
> timer/counter functionality. Based on the characteristics described
> above, we consider the TGU as a helper in the CoreSight subsystem.
> Its master device is the TPDM, which can transmit signals from other
> subsystems, and we reuse the existing ports mechanism to link the TPDM to
> the connected TGU.
>
> Here is a detailed example to explain how to use the TGU:
>
> In this example, the TGU is configured to use 2 conditions, 2 steps, and
> the timer. The goal is to look for one of two patterns which are generated
> from TPDM, giving priority to one, and then generate a trigger once the
> timer reaches a certain value. In other words, two conditions are used
> for the first step to look for the two patterns, where the one with the
> highest priority is used in the first condition. Then, in the second step,
> the timer is enabled and set to be compared to the given value at each
> clock cycle. These steps are better shown below.
>
> |-----------------|
> | |
> | TPDM |
> | |
> |-----------------|
> |
> |
> --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- ------
> | | |
> | | |--------------------| |
> | |---- ---> | | Go to next steps | |
> | | | |--- ---> | Enable timer | |
> | | v | | | |
> | | |-----------------| | |--------------------| |
> | | | | Yes | | |
> | | | inputs==0xB | ----->| | <-------- |
> | | | | | | No | |
> | No | |-----------------| | v | |
> | | | | |-----------------| | |
> | | | | | | | |
> | | | | | timer>=3 |-- |
> | | v | | | |
> | | |-----------------| | |-----------------| |
> | | | | Yes | | |
> | |--- | inputs==0xA | ----->| | Yes |
> | | | | |
> | |-----------------| v |
> | |-----------------| |
> | | | |
> | | Trigger | |
> | | | |
> | |-----------------| |
> | TGU | |
> |--- --- --- --- --- --- --- --- --- --- --- --- --- --- |--- --- -- |
> |
> v
> |-----------------|
> |The controllers |
> |which will use |
> |triggers further |
> |-----------------|
>
> steps:
> 1. Reset TGU /*it will disable tgu and reset dataset*/
> - echo 1 > /sys/bus/coresight/devices/<tgu-name>/reset_tgu
>
> 2. Set the pattern match for priority0 to 0xA = 0b1010 and for
> priority 1 to 0xB = 0b1011.
> - echo 0x11113232 > /sys/bus/coresight/devices/<tgu-name>/step0_priority0/reg0
> - echo 0x11113233 > /sys/bus/coresight/devices/<tgu-name>/step0_priority1/reg0
>
> Note:
> Bit distribution diagram for each priority register
> |-------------------------------------------------------------------|
> | Bits | Field Nam | Description |
> |-------------------------------------------------------------------|
> | | | 00 = bypass for OR output |
> | 29:28 | SEL_BIT7_TYPE2 | 01 = bypass for AND output |
> | | | 10 = sense input '0' is true|
> | | | 11 = sense input '1' is true|
> |-------------------------------------------------------------------|
> | | | 00 = bypass for OR output |
> | 25:24 | SEL_BIT6_TYPE2 | 01 = bypass for AND output |
> | | | 10 = sense input '0' is true|
> | | | 11 = sense input '1' is true|
> |-------------------------------------------------------------------|
> | | | 00 = bypass for OR output |
> | 21:20 | SEL_BIT5_TYPE2 | 01 = bypass for AND output |
> | | | 10 = sense input '0' is true|
> | | | 11 = sense input '1' is true|
> |-------------------------------------------------------------------|
> | | | 00 = bypass for OR output |
> | 17:16 | SEL_BIT4_TYPE2 | 01 = bypass for AND output |
> | | | 10 = sense input '0' is true|
> | | | 11 = sense input '1' is true|
> |-------------------------------------------------------------------|
> | | | 00 = bypass for OR output |
> | 13:12 | SEL_BIT3_TYPE2 | 01 = bypass for AND output |
> | | | 10 = sense input '0' is true|
> | | | 11 = sense input '1' is true|
> |-------------------------------------------------------------------|
> | | | 00 = bypass for OR output |
> | 9:8 | SEL_BIT2_TYPE2 | 01 = bypass for AND output |
> | | | 10 = sense input '0' is true|
> | | | 11 = sense input '1' is true|
> |-------------------------------------------------------------------|
> | | | 00 = bypass for OR output |
> | 5:4 | SEL_BIT1_TYPE2 | 01 = bypass for AND output |
> | | | 10 = sense input '0' is true|
> | | | 11 = sense input '1' is true|
> |-------------------------------------------------------------------|
> | | | 00 = bypass for OR output |
> | 1:0 | SEL_BIT0_TYPE2 | 01 = bypass for AND output |
> | | | 10 = sense input '0' is true|
> | | | 11 = sense input '1' is true|
> |-------------------------------------------------------------------|
> These bits are used to identify the signals we want to sense, with
> a maximum signal number of 140. For example, to sense the signal
> 0xA (binary 1010), we set the value of bits 0 to 13 to 3232, which
> represents 1010. The remaining bits are set to 1, as we want to use
> AND gate to summarize all the signals we want to sense here. For
> rising or falling edge detection of any input to the priority, set
> the remaining bits to 0 to use an OR gate.
>
> 3. look for the pattern for priority_i i=0,1.
> - echo 0x3 > /sys/bus/coresight/devices/<tgu-name>/step0_condition_decode/reg0
> - echo 0x30 > /sys/bus/coresight/devices/<tgu-name>/step0_condition_decode/reg1
>
> |-------------------------------------------------------------------------------|
> | Bits | Field Nam | Description |
> |-------------------------------------------------------------------------------|
> | | |For each decoded condition, this |
> | 24 | NOT |inverts the output. If the condition |
> | | |decodes to true, and the NOT field |
> | | |is '1', then the output is NOT true. |
> |-------------------------------------------------------------------------------|
> | | |When '1' the output from the associated|
> | 21 | BC0_COMP_ACTIVE |comparator will be actively included in|
> | | |the decoding of this particular |
> | | |condition. |
> |-------------------------------------------------------------------------------|
> | | |When '1' the output from the associated|
> | | |comparator will need to be 1 to affect |
> | 20 | BC0_COMP_HIGH |the decoding of this condition. |
> | | |Conversely, a '0' here requires a '0' |
> | | |from the comparator |
> |-------------------------------------------------------------------------------|
> | | |When '1' the output from the associated|
> | 17 | |comparator will be actively included in|
> | | TC0_COMP_ACTIVE |the decoding of this particular |
> | | |condition. |
> |-------------------------------------------------------------------------------|
> | | |When '1' the output from the associated|
> | | |comparator will need to be 1 to affect |
> | 16 | TC0_COMP_HIGH |the decoding of this particular |
> | | |condition.Conversely, a 0 here |
> | | |requires a '0' from the comparator |
> |-------------------------------------------------------------------------------|
> | | |When '1' the output from Priority_n |
> | | |OR logic will be actively |
> | 4n+3 | Priority_n_OR_ACTIVE|included in the decoding of |
> | | (n=0,1,2,3) |this particular condition. |
> | | | |
> |-------------------------------------------------------------------------------|
> | | |When '1' the output from Priority_n |
> | | |will need to be '1' to affect the |
> | 4n+2 | Priority_n_OR_HIGH |decoding of this particular |
> | | (n=0,1,2,3) |condition. Conversely, a '0' here |
> | | |requires a '0' from Priority_n OR logic|
> |-------------------------------------------------------------------------------|
> | | |When '1' the output from Priority_n |
> | | |AND logic will be actively |
> | 4n+1 |Priority_n_AND_ACTIVE|included in the decoding of this |
> | | (n=0,1,2,3) |particular condition. |
> | | | |
> |-------------------------------------------------------------------------------|
> | | |When '1' the output from Priority_n |
> | | |AND logic will need to be '1' to |
> | 4n | Priority_n_AND_HIGH |affect the decoding of this |
> | | (n=0,1,2,3) |particular condition. Conversely, |
> | | |a '0' here requires a '0' from |
> | | |Priority_n AND logic. |
> |-------------------------------------------------------------------------------|
> Since we use `priority_0` and `priority_1` with an AND output in step 2, we set `0x3`
> and `0x30` here to activate them.
>
> 4. Set NEXT_STEP = 1 and TC0_ENABLE = 1 so that when the conditions
> are met then the next step will be step 1 and the timer will be enabled.
> - echo 0x20008 > /sys/bus/coresight/devices/<tgu-name>/step0_condition_select/reg0
> - echo 0x20008 > /sys/bus/coresight/devices/<tgu-name>/step0_condition_select/reg1
>
> |-----------------------------------------------------------------------------|
> | Bits | Field Nam | Description |
> |-----------------------------------------------------------------------------|
> | | |This field defines the next step the |
> | 18:17 | NEXT_STEP |TGU will 'goto' for the associated |
> | | |Condition and Step. |
> |-----------------------------------------------------------------------------|
> | | |For each possible output trigger |
> | 13 | TRIGGER |available, set a '1' if you want |
> | | |the trigger to go active for the |
> | | |associated condition and Step. |
> |-----------------------------------------------------------------------------|
> | | |This will cause BC0 to increment if the|
> | 9 | BC0_INC |associated Condition is decoded for |
> | | |this step. |
> |-----------------------------------------------------------------------------|
> | | |This will cause BC0 to decrement if the|
> | 8 | BC0_DEC |associated Condition is decoded for |
> | | |this step. |
> |-----------------------------------------------------------------------------|
> | | |This will clear BC0 count value to 0 if|
> | 7 | BC0_CLEAR |the associated Condition is decoded |
> | | |for this step. |
> |-----------------------------------------------------------------------------|
> | | |This will cause TC0 to increment until |
> | 3 | TC0_ENABLE |paused or cleared if the associated |
> | | |Condition is decoded for this step. |
> |-----------------------------------------------------------------------------|
> | | |This will cause TC0 to pause until |
> | 2 | TC0_PAUSE |enabled if the associated Condition |
> | | |is decoded for this step. |
> |-----------------------------------------------------------------------------|
> | | |This will clear TC0 count value to 0 |
> | 1 | TC0_CLEAR |if the associated Condition is |
> | | |decoded for this step. |
> |-----------------------------------------------------------------------------|
> | | |This will set the done signal to the |
> | 0 | DONE |TGU FSM if the associated Condition |
> | | |is decoded for this step. |
> |-----------------------------------------------------------------------------|
> Based on the distribution diagram, we set `0x20008` for `priority0` and `priority1` to
> achieve "jump to step 1 and enable TC0" once the signal is sensed.
>
> 5. activate the timer comparison for this step.
> - echo 0x30000 > /sys/bus/coresight/devices/<tgu-name>/step1_condition_decode/reg0
>
> |-------------------------------------------------------------------------------|
> | | |When '1' the output from the associated|
> | 17 | |comparator will be actively included in|
> | | TC0_COMP_ACTIVE |the decoding of this particular |
> | | |condition. |
> |-------------------------------------------------------------------------------|
> | | |When '1' the output from the associated|
> | | |comparator will need to be 1 to affect |
> | 16 | TC0_COMP_HIGH |the decoding of this particular |
> | | |condition.Conversely, a 0 here |
> | | |requires a '0' from the comparator |
> |-------------------------------------------------------------------------------|
> Accroding to the decode distribution diagram , we give 0x30000 here to set 16th&17th bit
> to enable timer comparison.
>
> 6. Set the NEXT_STEP = 0 and TC0_PAUSE = 1 and TC0_CLEAR = 1 once the timer
> has reached the given value.
> - echo 0x6 > /sys/bus/coresight/devices/<tgu-name>/step1_condition_select/reg0
>
> 7. Enable Trigger 0 for TGU when the condition 0 is met in step1,
> i.e. when the timer reaches 3.
> - echo 0x2000 > /sys/bus/coresight/devices/<tgu-name>/step1_condition_select/default
>
> Note:
> 1. 'default' register allows for establishing the resultant action for
> the default condition
>
> 2. Trigger:For each possible output trigger available from
> the Design document, there are three triggers: interrupts, CTI,
> and Cross-TGU mapping.All three triggers can occur, but
> the choice of which trigger to use depends on the user's
> needs.
>
> 8. Compare the timer to 3 in step 1.
> - echo 0x3 > /sys/bus/coresight/devices/<tgu-name>/step1_timer/reg0
>
> 9. enale tgu
> - echo 1 > /sys/bus/coresight/devices/<tgu-name>/enable_tgu
>
> ---
> Link to V4: https://patchwork.kernel.org/project/linux-arm-msm/cover/20250423101054.954066-1-quic_songchai@quicinc.com/
>
> Changes in V5:
> - Update publish date and kernel_version in "sysfs-bus-coresight-devices-tgu"
> ---
> Link to V3: https://lore.kernel.org/all/20250227092640.2666894-1-quic_songchai@quicinc.com/
>
> Changes in V4:
> - Add changlog in coverletter.
> - Correct 'year' in Copyright in patch1.
> - Correct port mechansim description in patch1.
> - Remove 'tgu-steps','tgu-regs','tgu-conditions','tgu-timer-counters' from dt-binding
> and set them through reading DEVID register as per Mike's suggestion.
> - Modify tgu_disable func to make it have single return point in patch2 as per
> Mike's suggestion.
> - Use sysfs_emit in enable_tgu_show func in ptach2.
> - Remove redundant judgement in enable_tgu_store in patch2.
> - Correct typo in description in patch3.
> - Set default ret as SYSFS_GROUP_INVISIBLE, and returnret at end in pacth3 as
> per Mike's suggestion.
> - Remove tgu_dataset_ro definition in patch3
> - Use #define constants with explanations of what they are rather than
> arbitrary magic numbers in patch3 and patch4.
> - Check -EINVAL before using 'calculate_array_location()' in array in patch4.
> - Add 'default' in 'tgu_dataset_show''s switch part in patch4.
> - Document the value needed to initiate the reset in pacth7.
> - Check "value" in 'reset_tgu_store' and bail out with an error code if 0 in patch7.
> - Remove dev_dbg in 'reset_tgu_store' in patch7.
> ---
> Link to V2: https://lore.kernel.org/all/20241010073917.16023-1-quic_songchai@quicinc.com/
>
> Changes in V3:
> - Correct typo and format in dt-binding in patch1
> - Rebase to the latest kernel version
> ---
> Link to V1: https://lore.kernel.org/all/20240830092311.14400-1-quic_songchai@quicinc.com/
>
> Changes in V2:
> - Use real name instead of login name,
> - Correct typo and format in dt-binding and code.
> - Bring order in tgu_prob(declarations with and without assignments) as per
> Krzysztof's suggestion.
> - Add module device table in patch2.
> - Set const for tgu_common_grp and tgu_ids in patch2.
> - Initialize 'data' in tgu_ids to fix the warning in pacth2.
> ---
>
> Songwei Chai (7):
> dt-bindings: arm: Add support for Coresight TGU trace
> coresight: Add coresight TGU driver
> coresight-tgu: Add signal priority support
> coresight-tgu: Add TGU decode support
> coresight-tgu: add support to configure next action
> coresight-tgu: add timer/counter functionality for TGU
> coresight-tgu: add reset node to initialize
>
> .../testing/sysfs-bus-coresight-devices-tgu | 51 ++
> .../bindings/arm/qcom,coresight-tgu.yaml | 92 +++
> drivers/hwtracing/coresight/Kconfig | 11 +
> drivers/hwtracing/coresight/Makefile | 1 +
> drivers/hwtracing/coresight/coresight-tgu.c | 780 ++++++++++++++++++
> drivers/hwtracing/coresight/coresight-tgu.h | 255 ++++++
> 6 files changed, 1190 insertions(+)
> create mode 100644 Documentation/ABI/testing/sysfs-bus-coresight-devices-tgu
> create mode 100644 Documentation/devicetree/bindings/arm/qcom,coresight-tgu.yaml
> create mode 100644 drivers/hwtracing/coresight/coresight-tgu.c
> create mode 100644 drivers/hwtracing/coresight/coresight-tgu.h
>
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