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([2600:1700:e321:62f0:da43:aeff:fecc:bfd5]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-2985c2c103asm55441335ad.96.2025.11.14.05.36.03 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 14 Nov 2025 05:36:05 -0800 (PST) Sender: Guenter Roeck Message-ID: <55fba1a9-a24d-40b7-b97a-171f4a60a7dc@roeck-us.net> Date: Fri, 14 Nov 2025 05:36:02 -0800 Precedence: bulk X-Mailing-List: devicetree@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v7 2/2] watchdog: Add driver for Gunyah Watchdog To: hrishabh.rajput@oss.qualcomm.com, Bjorn Andersson , Konrad Dybcio , Wim Van Sebroeck , Rob Herring , Krzysztof Kozlowski , Conor Dooley Cc: linux-arm-msm@vger.kernel.org, linux-watchdog@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, Pavan Kondeti , Neil Armstrong , Dmitry Baryshkov References: <20251114-gunyah_watchdog-v7-0-f5c155b941d5@oss.qualcomm.com> <20251114-gunyah_watchdog-v7-2-f5c155b941d5@oss.qualcomm.com> Content-Language: en-US From: Guenter Roeck Autocrypt: addr=linux@roeck-us.net; keydata= xsFNBE6H1WcBEACu6jIcw5kZ5dGeJ7E7B2uweQR/4FGxH10/H1O1+ApmcQ9i87XdZQiB9cpN RYHA7RCEK2dh6dDccykQk3bC90xXMPg+O3R+C/SkwcnUak1UZaeK/SwQbq/t0tkMzYDRxfJ7 nyFiKxUehbNF3r9qlJgPqONwX5vJy4/GvDHdddSCxV41P/ejsZ8PykxyJs98UWhF54tGRWFl 7i1xvaDB9lN5WTLRKSO7wICuLiSz5WZHXMkyF4d+/O5ll7yz/o/JxK5vO/sduYDIlFTvBZDh gzaEtNf5tQjsjG4io8E0Yq0ViobLkS2RTNZT8ICq/Jmvl0SpbHRvYwa2DhNsK0YjHFQBB0FX IdhdUEzNefcNcYvqigJpdICoP2e4yJSyflHFO4dr0OrdnGLe1Zi/8Xo/2+M1dSSEt196rXaC kwu2KgIgmkRBb3cp2vIBBIIowU8W3qC1+w+RdMUrZxKGWJ3juwcgveJlzMpMZNyM1jobSXZ0 VHGMNJ3MwXlrEFPXaYJgibcg6brM6wGfX/LBvc/haWw4yO24lT5eitm4UBdIy9pKkKmHHh7s jfZJkB5fWKVdoCv/omy6UyH6ykLOPFugl+hVL2Prf8xrXuZe1CMS7ID9Lc8FaL1ROIN/W8Vk BIsJMaWOhks//7d92Uf3EArDlDShwR2+D+AMon8NULuLBHiEUQARAQABzTJHdWVudGVyIFJv ZWNrIChMaW51eCBhY2NvdW50KSA8bGludXhAcm9lY2stdXMubmV0PsLBgQQTAQIAKwIbAwYL CQgHAwIGFQgCCQoLBBYCAwECHgECF4ACGQEFAmgrMyQFCSbODQkACgkQyx8mb86fmYGcWRAA oRwrk7V8fULqnGGpBIjp7pvR187Yzx+lhMGUHuM5H56TFEqeVwCMLWB2x1YRolYbY4MEFlQg VUFcfeW0OknSr1s6wtrtQm0gdkolM8OcCL9ptTHOg1mmXa4YpW8QJiL0AVtbpE9BroeWGl9v 2TGILPm9mVp+GmMQgkNeCS7Jonq5f5pDUGumAMguWzMFEg+Imt9wr2YA7aGen7KPSqJeQPpj onPKhu7O/KJKkuC50ylxizHzmGx+IUSmOZxN950pZUFvVZH9CwhAAl+NYUtcF5ry/uSYG2U7 DCvpzqOryJRemKN63qt1bjF6cltsXwxjKOw6CvdjJYA3n6xCWLuJ6yk6CAy1Ukh545NhgBAs rGGVkl6TUBi0ixL3EF3RWLa9IMDcHN32r7OBhw6vbul8HqyTFZWY2ksTvlTl+qG3zV6AJuzT WdXmbcKN+TdhO5XlxVlbZoCm7ViBj1+PvIFQZCnLAhqSd/DJlhaq8fFXx1dCUPgQDcD+wo65 qulV/NijfU8bzFfEPgYP/3LP+BSAyFs33y/mdP8kbMxSCjnLEhimQMrSSo/To1Gxp5C97fw5 3m1CaMILGKCmfI1B8iA8zd8ib7t1Rg0qCwcAnvsM36SkrID32GfFbv873bNskJCHAISK3Xkz qo7IYZmjk/IJGbsiGzxUhvicwkgKE9r7a1rOwU0ETofVZwEQALlLbQeBDTDbwQYrj0gbx3bq 7kpKABxN2MqeuqGr02DpS9883d/t7ontxasXoEz2GTioevvRmllJlPQERVxM8gQoNg22twF7 pB/zsrIjxkE9heE4wYfN1AyzT+AxgYN6f8hVQ7Nrc9XgZZe+8IkuW/Nf64KzNJXnSH4u6nJM J2+Dt274YoFcXR1nG76Q259mKwzbCukKbd6piL+VsT/qBrLhZe9Ivbjq5WMdkQKnP7gYKCAi pNVJC4enWfivZsYupMd9qn7Uv/oCZDYoBTdMSBUblaLMwlcjnPpOYK5rfHvC4opxl+P/Vzyz 6WC2TLkPtKvYvXmdsI6rnEI4Uucg0Au/Ulg7aqqKhzGPIbVaL+U0Wk82nz6hz+WP2ggTrY1w ZlPlRt8WM9w6WfLf2j+PuGklj37m+KvaOEfLsF1v464dSpy1tQVHhhp8LFTxh/6RWkRIR2uF I4v3Xu/k5D0LhaZHpQ4C+xKsQxpTGuYh2tnRaRL14YMW1dlI3HfeB2gj7Yc8XdHh9vkpPyuT nY/ZsFbnvBtiw7GchKKri2gDhRb2QNNDyBnQn5mRFw7CyuFclAksOdV/sdpQnYlYcRQWOUGY HhQ5eqTRZjm9z+qQe/T0HQpmiPTqQcIaG/edgKVTUjITfA7AJMKLQHgp04Vylb+G6jocnQQX JqvvP09whbqrABEBAAHCwWUEGAECAA8CGwwFAmgrMyQFCSbODQkACgkQyx8mb86fmYHlgg/9 H5JeDmB4jsreE9Bn621wZk7NMzxy9STxiVKSh8Mq4pb+IDu1RU2iLyetCY1TiJlcxnE362kj njrfAdqyPteHM+LU59NtEbGwrfcXdQoh4XdMuPA5ADetPLma3YiRa3VsVkLwpnR7ilgwQw6u dycEaOxQ7LUXCs0JaGVVP25Z2hMkHBwx6BlW6EZLNgzGI2rswSZ7SKcsBd1IRHVf0miwIFYy j/UEfAFNW+tbtKPNn3xZTLs3quQN7GdYLh+J0XxITpBZaFOpwEKV+VS36pSLnNl0T5wm0E/y scPJ0OVY7ly5Vm1nnoH4licaU5Y1nSkFR/j2douI5P7Cj687WuNMC6CcFd6j72kRfxklOqXw zvy+2NEcXyziiLXp84130yxAKXfluax9sZhhrhKT6VrD45S6N3HxJpXQ/RY/EX35neH2/F7B RgSloce2+zWfpELyS1qRkCUTt1tlGV2p+y2BPfXzrHn2vxvbhEn1QpQ6t+85FKN8YEhJEygJ F0WaMvQMNrk9UAUziVcUkLU52NS9SXqpVg8vgrO0JKx97IXFPcNh0DWsSj/0Y8HO/RDkGXYn FDMj7fZSPKyPQPmEHg+W/KzxSSfdgWIHF2QaQ0b2q1wOSec4Rti52ohmNSY+KNIW/zODhugJ np3900V20aS7eD9K8GTU0TGC1pyz6IVJwIE= In-Reply-To: <20251114-gunyah_watchdog-v7-2-f5c155b941d5@oss.qualcomm.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 11/13/25 23:57, Hrishabh Rajput via B4 Relay wrote: > From: Hrishabh Rajput > > On Qualcomm SoCs running under the Gunyah hypervisor, access to watchdog > through MMIO is not available on all platforms. Depending on the > hypervisor configuration, the watchdog is either fully emulated or > exposed via ARM's SMC Calling Conventions (SMCCC) through the Vendor > Specific Hypervisor Service Calls space. > > Add driver to support the SMC-based watchdog provided by the Gunyah > Hypervisor. Device registration is done in the QCOM SCM driver after > checks to restrict the watchdog initialization to Qualcomm devices > running under Gunyah. > > Gunyah watchdog is not a hardware but an SMC-based vendor-specific > hypervisor interface provided by the Gunyah hypervisor. The design > involving QCOM SCM driver for registering the platform device has been > devised to avoid adding non-hardware nodes to devicetree. > > Signed-off-by: Hrishabh Rajput > --- > MAINTAINERS | 1 + > drivers/watchdog/Kconfig | 13 +++ > drivers/watchdog/Makefile | 1 + > drivers/watchdog/gunyah_wdt.c | 260 ++++++++++++++++++++++++++++++++++++++++++ > 4 files changed, 275 insertions(+) > > diff --git a/MAINTAINERS b/MAINTAINERS > index ddecf1ef3bed..f80e762aa324 100644 > --- a/MAINTAINERS > +++ b/MAINTAINERS > @@ -3215,6 +3215,7 @@ F: arch/arm64/boot/dts/qcom/ > F: drivers/bus/qcom* > F: drivers/firmware/qcom/ > F: drivers/soc/qcom/ > +F: drivers/watchdog/gunyah_wdt.c > F: include/dt-bindings/arm/qcom,ids.h > F: include/dt-bindings/firmware/qcom,scm.h > F: include/dt-bindings/soc/qcom* > diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig > index 05008d937e40..bc6db9a1c116 100644 > --- a/drivers/watchdog/Kconfig > +++ b/drivers/watchdog/Kconfig > @@ -2354,4 +2354,17 @@ config KEEMBAY_WATCHDOG > To compile this driver as a module, choose M here: the > module will be called keembay_wdt. > > +config GUNYAH_WATCHDOG > + tristate "Qualcomm Gunyah Watchdog" > + depends on ARCH_QCOM || COMPILE_TEST > + depends on HAVE_ARM_SMCCC > + select WATCHDOG_CORE > + help > + Say Y here to include support for watchdog timer provided by the > + Gunyah hypervisor. The driver uses ARM SMC Calling Convention (SMCCC) > + to interact with Gunyah Watchdog. > + > + To compile this driver as a module, choose M here: the > + module will be called gunyah_wdt. > + > endif # WATCHDOG > diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile > index b680e4d3c1bc..1215efb7816d 100644 > --- a/drivers/watchdog/Makefile > +++ b/drivers/watchdog/Makefile > @@ -102,6 +102,7 @@ obj-$(CONFIG_MSC313E_WATCHDOG) += msc313e_wdt.o > obj-$(CONFIG_APPLE_WATCHDOG) += apple_wdt.o > obj-$(CONFIG_SUNPLUS_WATCHDOG) += sunplus_wdt.o > obj-$(CONFIG_MARVELL_GTI_WDT) += marvell_gti_wdt.o > +obj-$(CONFIG_GUNYAH_WATCHDOG) += gunyah_wdt.o > > # X86 (i386 + ia64 + x86_64) Architecture > obj-$(CONFIG_ACQUIRE_WDT) += acquirewdt.o > diff --git a/drivers/watchdog/gunyah_wdt.c b/drivers/watchdog/gunyah_wdt.c > new file mode 100644 > index 000000000000..addfd1733ad1 > --- /dev/null > +++ b/drivers/watchdog/gunyah_wdt.c > @@ -0,0 +1,260 @@ > +// SPDX-License-Identifier: GPL-2.0-only > +/* > + * Copyright (c) Qualcomm Technologies, Inc. and/or its subsidiaries. > + */ > + > +#include > +#include > +#include > +#include > +#include > +#include > +#include > +#include > + > +#define GUNYAH_WDT_SMCCC_CALL_VAL(func_id) \ > + ARM_SMCCC_CALL_VAL(ARM_SMCCC_FAST_CALL, ARM_SMCCC_SMC_32,\ > + ARM_SMCCC_OWNER_VENDOR_HYP, func_id) > + > +/* SMCCC function IDs for watchdog operations */ > +#define GUNYAH_WDT_CONTROL GUNYAH_WDT_SMCCC_CALL_VAL(0x0005) > +#define GUNYAH_WDT_STATUS GUNYAH_WDT_SMCCC_CALL_VAL(0x0006) > +#define GUNYAH_WDT_PING GUNYAH_WDT_SMCCC_CALL_VAL(0x0007) > +#define GUNYAH_WDT_SET_TIME GUNYAH_WDT_SMCCC_CALL_VAL(0x0008) > + > +/* > + * Control values for GUNYAH_WDT_CONTROL. > + * Bit 0 is used to enable or disable the watchdog. If this bit is set, > + * then the watchdog is enabled and vice versa. > + * Bit 1 should always be set to 1 as this bit is reserved in Gunyah and > + * it's expected to be 1. > + */ > +#define WDT_CTRL_ENABLE (BIT(1) | BIT(0)) > +#define WDT_CTRL_DISABLE BIT(1) > + > +enum gunyah_error { > + GUNYAH_ERROR_OK = 0, > + GUNYAH_ERROR_UNIMPLEMENTED = -1, > + GUNYAH_ERROR_ARG_INVAL = 1, > +}; > + > +/** > + * gunyah_error_remap() - Remap Gunyah hypervisor errors into a Linux error code > + * @gunyah_error: Gunyah hypercall return value > + */ > +static inline int gunyah_error_remap(enum gunyah_error gunyah_error) > +{ > + switch (gunyah_error) { > + case GUNYAH_ERROR_OK: > + return 0; > + case GUNYAH_ERROR_UNIMPLEMENTED: > + return -EOPNOTSUPP; > + default: > + return -EINVAL; > + } > +} > + > +static int gunyah_wdt_call(unsigned long func_id, unsigned long arg1, > + unsigned long arg2) > +{ > + struct arm_smccc_res res; > + > + arm_smccc_1_1_smc(func_id, arg1, arg2, &res); > + return gunyah_error_remap(res.a0); > +} > + > +static int gunyah_wdt_start(struct watchdog_device *wdd) > +{ > + unsigned int timeout_ms; > + struct device *dev = wdd->parent; > + int ret; > + > + ret = gunyah_wdt_call(GUNYAH_WDT_CONTROL, WDT_CTRL_DISABLE, 0); > + if (ret && watchdog_active(wdd)) { > + dev_err(dev, "%s: Failed to stop gunyah wdt %d\n", __func__, ret); > + return ret; > + } > + > + timeout_ms = wdd->timeout * 1000; > + ret = gunyah_wdt_call(GUNYAH_WDT_SET_TIME, timeout_ms, timeout_ms); > + if (ret) { > + dev_err(dev, "%s: Failed to set timeout for gunyah wdt %d\n", > + __func__, ret); > + return ret; > + } > + > + ret = gunyah_wdt_call(GUNYAH_WDT_CONTROL, WDT_CTRL_ENABLE, 0); > + if (ret) > + dev_err(dev, "%s: Failed to start gunyah wdt %d\n", __func__, ret); > + > + return ret; > +} > + > +static int gunyah_wdt_stop(struct watchdog_device *wdd) > +{ > + return gunyah_wdt_call(GUNYAH_WDT_CONTROL, WDT_CTRL_DISABLE, 0); > +} > + > +static int gunyah_wdt_ping(struct watchdog_device *wdd) > +{ > + return gunyah_wdt_call(GUNYAH_WDT_PING, 0, 0); > +} > + > +static int gunyah_wdt_set_timeout(struct watchdog_device *wdd, > + unsigned int timeout_sec) > +{ > + wdd->timeout = timeout_sec; > + > + if (watchdog_active(wdd)) > + return gunyah_wdt_start(wdd); > + > + return 0; > +} > + > +static int gunyah_wdt_get_time_since_last_ping(void) > +{ > + struct arm_smccc_res res; > + > + arm_smccc_1_1_smc(GUNYAH_WDT_STATUS, 0, 0, &res); > + if (res.a0) > + return gunyah_error_remap(res.a0); > + > + return res.a2 / 1000; > +} > + > +static unsigned int gunyah_wdt_get_timeleft(struct watchdog_device *wdd) > +{ > + int seconds_since_last_ping; > + > + seconds_since_last_ping = gunyah_wdt_get_time_since_last_ping(); > + if (seconds_since_last_ping < 0 || > + seconds_since_last_ping > wdd->timeout) > + return 0; > + > + return wdd->timeout - seconds_since_last_ping; > +} > + > +static int gunyah_wdt_restart(struct watchdog_device *wdd, > + unsigned long action, void *data) > +{ > + /* Set timeout to 1ms and send a ping */ > + gunyah_wdt_call(GUNYAH_WDT_CONTROL, WDT_CTRL_DISABLE, 0); > + gunyah_wdt_call(GUNYAH_WDT_SET_TIME, 1, 1); > + gunyah_wdt_call(GUNYAH_WDT_CONTROL, WDT_CTRL_ENABLE, 0); > + gunyah_wdt_call(GUNYAH_WDT_PING, 0, 0); > + > + /* Wait to make sure reset occurs */ > + mdelay(100); > + > + return 0; > +} > + > +static const struct watchdog_info gunyah_wdt_info = { > + .identity = "Gunyah Watchdog", > + .options = WDIOF_SETTIMEOUT > + | WDIOF_KEEPALIVEPING > + | WDIOF_MAGICCLOSE, > +}; > + > +static const struct watchdog_ops gunyah_wdt_ops = { > + .owner = THIS_MODULE, > + .start = gunyah_wdt_start, > + .stop = gunyah_wdt_stop, > + .ping = gunyah_wdt_ping, > + .set_timeout = gunyah_wdt_set_timeout, > + .get_timeleft = gunyah_wdt_get_timeleft, > + .restart = gunyah_wdt_restart > +}; > + > +static int gunyah_wdt_probe(struct platform_device *pdev) > +{ > + struct watchdog_device *wdd; > + struct device *dev = &pdev->dev; > + int ret; > + > + ret = gunyah_wdt_call(GUNYAH_WDT_STATUS, 0, 0); > + if (ret) { > + dev_err_probe(dev, ret, "status check failed\n"); > + return ret; From the context, it seems to me that this should fail silently with -ENODEV if the function returns -EOPNOTSUPP (not implemented). Guenter