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([2600:1700:e321:62f0:da43:aeff:fecc:bfd5]) by smtp.gmail.com with ESMTPSA id 41be03b00d2f7-b93bef83380sm2466159a12.31.2025.10.31.08.42.25 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 31 Oct 2025 08:42:26 -0700 (PDT) Sender: Guenter Roeck Message-ID: Date: Fri, 31 Oct 2025 08:42:24 -0700 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v4 2/2] watchdog: Add driver for Gunyah Watchdog To: Dmitry Baryshkov , hrishabh.rajput@oss.qualcomm.com Cc: Bjorn Andersson , Konrad Dybcio , Wim Van Sebroeck , Rob Herring , Krzysztof Kozlowski , Conor Dooley , linux-arm-msm@vger.kernel.org, linux-watchdog@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, Pavan Kondeti , Neil Armstrong References: <20251031-gunyah_watchdog-v4-0-7abb1ee11315@oss.qualcomm.com> <20251031-gunyah_watchdog-v4-2-7abb1ee11315@oss.qualcomm.com> <4bxoananq55f7u4kckqjof37or6fflppmbyyc3j6noodzr75nt@vtfxbnhrcgzy> 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: <4bxoananq55f7u4kckqjof37or6fflppmbyyc3j6noodzr75nt@vtfxbnhrcgzy> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 10/31/25 07:36, Dmitry Baryshkov wrote: > On Fri, Oct 31, 2025 at 10:18:14AM +0000, 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 SMEM driver after checks >> to restrict the watchdog initialization to Qualcomm devices. >> module_exit() is intentionally not implemented as this driver is >> intended to be a persistent module. >> >> Signed-off-by: Hrishabh Rajput >> --- >> MAINTAINERS | 1 + >> drivers/watchdog/Kconfig | 14 +++ >> drivers/watchdog/Makefile | 1 + >> drivers/watchdog/gunyah_wdt.c | 249 ++++++++++++++++++++++++++++++++++++++++++ >> 4 files changed, 265 insertions(+) >> >> diff --git a/MAINTAINERS b/MAINTAINERS >> index c0b444e5fd5a..56dbd0d3e31b 100644 >> --- a/MAINTAINERS >> +++ b/MAINTAINERS >> @@ -3083,6 +3083,7 @@ 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 0c25b2ed44eb..f0dee04b3650 100644 >> --- a/drivers/watchdog/Kconfig >> +++ b/drivers/watchdog/Kconfig >> @@ -2343,4 +2343,18 @@ 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 >> + depends on OF >> + 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 bbd4d62d2cc3..308379782bc3 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..bfe8b656d674 >> --- /dev/null >> +++ b/drivers/watchdog/gunyah_wdt.c >> @@ -0,0 +1,249 @@ >> +// SPDX-License-Identifier: GPL-2.0-only >> +/* >> + * Copyright (c) Qualcomm Technologies, Inc. and/or its subsidiaries. >> + */ >> + >> +#include >> +#include >> +#include >> +#include >> +#include >> +#include > > Is this header used here? > >> +#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) > > What about calls 0-4? > >> + >> +/* >> + * 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) >> +{ > > struct arm_smccc_res res; > > There is no need to pass it through arguments. > >> + 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) >> +{ >> + struct arm_smccc_res res; >> + unsigned int timeout_ms; >> + struct device *dev = wdd->parent; >> + int ret; >> + >> + ret = gunyah_wdt_call(GUNYAH_WDT_CONTROL, WDT_CTRL_DISABLE, 0, &res); >> + 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, &res); >> + 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, &res); >> + 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) >> +{ >> + struct arm_smccc_res res; >> + >> + return gunyah_wdt_call(GUNYAH_WDT_CONTROL, WDT_CTRL_DISABLE, 0, &res); >> +} >> + >> +static int gunyah_wdt_ping(struct watchdog_device *wdd) >> +{ >> + struct arm_smccc_res res; >> + >> + return gunyah_wdt_call(GUNYAH_WDT_PING, 0, 0, &res); >> +} >> + >> +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 unsigned int gunyah_wdt_get_timeleft(struct watchdog_device *wdd) >> +{ >> + struct arm_smccc_res res; >> + unsigned int seconds_since_last_ping; >> + int ret; >> + >> + ret = gunyah_wdt_call(GUNYAH_WDT_STATUS, 0, 0, &res); >> + if (ret) >> + return 0; > > This is the only place which passes something back in res. Please wrap > it separately and return int value. > >> + >> + seconds_since_last_ping = res.a2 / 1000; >> + if (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) >> +{ >> + struct arm_smccc_res res; >> + >> + /* Set timeout to 1ms and send a ping */ >> + gunyah_wdt_call(GUNYAH_WDT_CONTROL, WDT_CTRL_ENABLE, 0, &res); >> + gunyah_wdt_call(GUNYAH_WDT_SET_TIME, 1, 1, &res); >> + gunyah_wdt_call(GUNYAH_WDT_PING, 0, 0, &res); >> + >> + /* Wait to make sure reset occurs */ >> + mdelay(100); >> + >> + return 0; >> +} >> + >> +static const struct watchdog_info gunyah_wdt_info = { >> + .identity = "Gunyah Watchdog", >> + .firmware_version = 0, > > =0 is default and can be omited > >> + .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 arm_smccc_res res; >> + struct watchdog_device *wdd; >> + struct device *dev = &pdev->dev; >> + int ret; >> + >> + ret = gunyah_wdt_call(GUNYAH_WDT_STATUS, 0, 0, &res); >> + if (ret) { >> + dev_dbg(dev, "Watchdog interface status check failed with %d\n", ret); > > dev_err > Then -ENODEV is inappropriate and the actual error should be returned. Guenter >> + return -ENODEV;