Gunyah is a Type-I hypervisor which was introduced in the patch series
[1]. It is an open source hypervisor. The source repo is available at
[2].
The Gunyah Hypervisor doesn't allow its Virtual Machines to directly
access the MMIO watchdog. It either provides the fully emulated MMIO
based watchdog interface or the SMC-based watchdog interface depending
on the hypervisor configuration.
The SMC-based watchdog follows ARM's SMC Calling Convention (SMCCC)
version 1.1 and uses Vendor Specific Hypervisor Service Calls space.
This patch series adds support for the SMC-based watchdog interface
provided by the Gunyah Hypervisor.
This series is tested on SM8750 platform.
[1]
https://lore.kernel.org/all/20240222-gunyah-v17-0-1e9da6763d38@quicinc.com/
[2]
https://github.com/quic/gunyah-hypervisor
Signed-off-by: Hrishabh Rajput <hrishabh.rajput@oss.qualcomm.com>
---
Changes in v4:
- Move the contents of gunyah_wdt_init() to qcom_smem_probe() to make
sure we're registering the watchdog only on the Qualcomm devices.
- Link to v3: https://lore.kernel.org/r/20251028-gunyah_watchdog-v3-1-e6d1ea438b1d@oss.qualcomm.com
Changes in v3:
- Move back to platform driver model. In module init, determine if we're
running on a Qualcomm device and there is no supported memory-mapped
watchdog present. Then proceed to register platform device and driver
for SMC-based Gunyah watchdog.
- To determine if we're running on a Qualcomm device we're checking the
presence of "qcom,smem" compatible devicetree node. As an alternative,
we also tried using socinfo for the same purpose. When both
gunyah_wdt and socinfo drivers were made built-in, it couldn't be
ensured that the socinfo driver probed successfully before gunyah_wdt
init was called. Hence, we resorted to the devicetree node approach.
- Limit the errors listed in gunyah_error to the ones that can be
produced by the driver.
- Link to v2: https://lore.kernel.org/r/20251006-gunyah_watchdog-v2-1-b99d41d45450@oss.qualcomm.com
Changes in v2:
- Move away from platform driver model since the devicetree overlay does
not happen by default.
See https://lore.kernel.org/all/91002189-9d9e-48a2-8424-c42705fed3f8@quicinc.com/
- Only when MMIO-based watchdog device is absent in the devicetree,
proceed to detect SMC-based watchdog using GUNYAH_WDT_STATUS SMC and
initialize if SMC returns success.
- Implement pm notifiers as gunyah_wdt is no longer a platform driver so
dev_pm_ops cannot be used.
- Pretimeout IRQ is no longer supported.
- Remove struct gunyah_wdt since it is not required.
- Move the contents of gunyah_errno.h to gunyah_wdt.c.
- Link to v1: https://lore.kernel.org/r/20250903-gunyah_watchdog-v1-0-3ae690530e4b@oss.qualcomm.com
---
Hrishabh Rajput (2):
soc: qcom: smem: Register gunyah watchdog device
watchdog: Add driver for Gunyah Watchdog
MAINTAINERS | 1 +
drivers/soc/qcom/smem.c | 37 +++++++
drivers/watchdog/Kconfig | 14 +++
drivers/watchdog/Makefile | 1 +
drivers/watchdog/gunyah_wdt.c | 249 ++++++++++++++++++++++++++++++++++++++++++
5 files changed, 302 insertions(+)
---
base-commit: 038d61fd642278bab63ee8ef722c50d10ab01e8f
change-id: 20250903-gunyah_watchdog-2d2649438e29
Best regards,
--
Hrishabh Rajput <hrishabh.rajput@oss.qualcomm.com>