Message-Id: <20251102-multi_waitq_scm-v8-0-d71ee7b93b62@oss.qualcomm.com>
Date: Sun, 02 Nov 2025 13:48:44 +0530
From: Shivendra Pratap <shivendra.pratap@....qualcomm.com>
To: Bjorn Andersson <andersson@...nel.org>,
        Konrad Dybcio <konradybcio@...nel.org>
Cc: linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org,
        Unnathi Chalicheemala <unnathi.chalicheemala@....qualcomm.com>,
        Shivendra Pratap <shivendra.pratap@....qualcomm.com>,
        Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
Subject: [PATCH v8 0/3] SCM: Support latest version of waitq-aware firmware

This series adds support for the latest improvements made in SCM
firmware that allow for multiple wait-queues in firmware.

To support multi VM synchronization when VMs make SMC calls on same CPU,
waitqueue mechanism is added in firmware which runs at EL2 & EL3 exception
levels.

Thanks to Unnathi for bringing the path to this level of maturity.
P.S. While at Qualcomm, Guru Das Srinagesh authored the initial version of
these patches.
Thanks Guru!

Signed-off-by: Unnathi Chalicheemala <unnathi.chalicheemala@....qualcomm.com>
Signed-off-by: Shivendra Pratap <shivendra.pratap@....qualcomm.com>

---
Changes in v8:
- Replace "of_node_to_fwnode" with "of_fwnode_handle to align
  with current kernel version.
- Add NULL check for parent_irq_node in function qcom_scm_get_waitq_irq. 
- Change declaration of qcom_scm_get_waitq_irq and pass qcom_scm pointer.
- Set the scm->wq_cnt to one, in case where waitqueue is not
  supported by firmware and continue to probe the qcom_scm driver.
- Link to v7: https://lore.kernel.org/all/20250523-multi_waitq_scm-v7-0-5b51b60ed396@oss.qualcomm.com/

Changes in v7:
- Assume failing scm call to mean WAITQ_GET_INFO is not supported on target
  as qcom_scm_is_call_available() is handled in Qualcomm firmware's TZ (EL3),
  which doesn’t implement WAITQ_GET_INFO, and therefore always returns 0.
- Link to v6: https://lore.kernel.org/r/20250425-multi_waitq_scm-v6-0-cba8ca5a6d03@oss.qualcomm.com

Changes in v6:
- Added R-b tag from Bartosz for first patch.
- Check if QCOM_SCM_WAITQ_GET_INFO is available before making scm call,
instead of assuming failing scm call to mean WAITQ_GET_INFO is not
supported on target.
- Add a new patch to check for waitq idle state in wait_for_wq_completion().
- Link to v5: https://lore.kernel.org/all/20250227-multi_waitq_scm-v5-0-16984ea97edf@oss.qualcomm.com/

Changes in v5:
- Use GIC_SPI and GIC_ESPI macros from dt-bindings instead of redefining
- Modified qcom_scm_query_waitq_count to take struct qcom_scm as
argument; scm is anyway stored to global struct __scm after
smp_store_and_release().
- Tested on SM8650 which has multi-waitq support and SM8550, which
doesn't. No error logs are seen.
-Link to v4: https://lore.kernel.org/all/cover.1730742637.git.quic_uchalich@quicinc.com/

Changes in v4:
- Moving back to redefining GIC_IRQ_TYPE_SPI and GIC_IRQ_TYPE_ESPI macros
in qcom_scm as seeing compilation issues in linux/irq.h when including
arm-gic header. Will send a fixes patch and move to dt-bindings in next patchset.
- Fixed a few compilation errors.
- Link to v3: https://lore.kernel.org/all/cover.1730735881.git.quic_uchalich@quicinc.com/

Changes in v3:
- Use GIC_SPI and GIC_ESPI macros from dt-bindings instead of redefining
- Prettified qcom_scm_fill_irq_fwspec_params()
- Moved waitq initialization before smp_store_release()
- There is no Gunyah hypercall API that can be used to fetch IRQ information hence
introducing new SCM call.
- Link to v2: https://lore.kernel.org/all/cover.1724968351.git.quic_uchalich@quicinc.com/

Changes in v2:
- Dropped "Initialize waitq before setting global __scm" as it was merged here:
https://lore.kernel.org/r/1711034642-22860-4-git-send-email-quic_mojha@quicinc.com
- Decoupled "Remove QCOM_SMC_WAITQ_FLAG_WAKE_ALL" from series
- Converted xarray to a statically sized array
- Initialize waitq array in probe function
- Remove reinit of waitq completion struct in scm_get_completion()
- Introduced new APIs to get no. of waitqueue contexts and waitqueue IRQ no.
directly from firmware.
- Link to v1: https://lore.kernel.org/all/20240228-multi_waitq-v1-0-ccb096419af0@quicinc.com/

---
Unnathi Chalicheemala (3):
      firmware: qcom_scm: Add API to get waitqueue IRQ info
      firmware: qcom_scm: Support multiple waitq contexts
      firmware: qcom_scm: Check for waitq state in wait_for_wq_completion()

 drivers/firmware/qcom/qcom_scm.c | 129 +++++++++++++++++++++++++++++++++------
 drivers/firmware/qcom/qcom_scm.h |   1 +
 2 files changed, 111 insertions(+), 19 deletions(-)
---
base-commit: f9ba12abc5282bf992f9a9ae87ad814fd03a0270
change-id: 20250227-multi_waitq_scm-5bf05480b7b1

Best regards,
-- 
Shivendra Pratap <shivendra.pratap@....qualcomm.com>

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