Message-ID: <59f0a8f2-0a66-40df-8fbb-70ca1c228990@roeck-us.net>
Date: Thu, 13 Mar 2025 14:15:37 -0700
From: Guenter Roeck <linux@...ck-us.net>
To: Diogo Ivo <diogo.ivo@...mens.com>, "Rafael J. Wysocki"
 <rafael@...nel.org>, Len Brown <lenb@...nel.org>,
 Wim Van Sebroeck <wim@...ux-watchdog.org>
Cc: linux-kernel@...r.kernel.org, linux-acpi@...r.kernel.org,
 linux-watchdog@...r.kernel.org, jan.kiszka@...mens.com,
 benedikt.niedermayr@...mens.com
Subject: Re: [PATCH v2 1/2] watchdog: Add driver for Intel OC WDT

On 3/12/25 08:46, Diogo Ivo wrote:
> Add a driver for the Intel Over-Clocking Watchdog found in Intel
> Platform Controller (PCH) chipsets. This watchdog is controlled
> via a simple single-register interface and would otherwise be
> standard except for the presence of a LOCK bit that can only be
> set once per power cycle, needing extra handling around it.
> 
> Signed-off-by: Diogo Ivo <diogo.ivo@...mens.com>

Reviewed-by: Guenter Roeck <linux@...ck-us.net>

> ---
> v1->v2:
>   - Split v1 into two patches, adding the ACPI IDs in a separate patch
>   - Initialize hearbeat module parameter to zero
>   - Clarify wording around lock handling
>   - Properly print resource with %pR when failing to obtain it
>   - Enable compile testing and add dependency on HAS_IOPORT
>   - Drop unneeded ACPI_PTR() and MODULE_ALIAS()
> ---
> ---
>   drivers/watchdog/Kconfig        |  11 ++
>   drivers/watchdog/Makefile       |   1 +
>   drivers/watchdog/intel_oc_wdt.c | 233 ++++++++++++++++++++++++++++++++++++++++
>   3 files changed, 245 insertions(+)
> 
> diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
> index f81705f8539aa0b12d156a86aae521aa40b4527d..94d058c6c49a19f8fee97d82ceb653b60d1944cd 100644
> --- a/drivers/watchdog/Kconfig
> +++ b/drivers/watchdog/Kconfig
> @@ -1350,6 +1350,17 @@ config INTEL_MID_WATCHDOG
>   
>   	  To compile this driver as a module, choose M here.
>   
> +config INTEL_OC_WATCHDOG
> +	tristate "Intel OC Watchdog"
> +	depends on (X86 || COMPILE_TEST) && ACPI && HAS_IOPORT
> +	select WATCHDOG_CORE
> +	help
> +	  Hardware driver for Intel Over-Clocking watchdog present in
> +	  Platform Controller Hub (PCH) chipsets.
> +
> +	  To compile this driver as a module, choose M here: the
> +	  module will be called intel_oc_wdt.
> +
>   config ITCO_WDT
>   	tristate "Intel TCO Timer/Watchdog"
>   	depends on X86 && PCI
> diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
> index 8411626fa162268e8ccd06349f7193b15a9d281a..3a13f3e80a0f460b99b4f1592fcf17cc6428876b 100644
> --- a/drivers/watchdog/Makefile
> +++ b/drivers/watchdog/Makefile
> @@ -149,6 +149,7 @@ obj-$(CONFIG_W83977F_WDT) += w83977f_wdt.o
>   obj-$(CONFIG_MACHZ_WDT) += machzwd.o
>   obj-$(CONFIG_SBC_EPX_C3_WATCHDOG) += sbc_epx_c3.o
>   obj-$(CONFIG_INTEL_MID_WATCHDOG) += intel-mid_wdt.o
> +obj-$(CONFIG_INTEL_OC_WATCHDOG) += intel_oc_wdt.o
>   obj-$(CONFIG_INTEL_MEI_WDT) += mei_wdt.o
>   obj-$(CONFIG_NI903X_WDT) += ni903x_wdt.o
>   obj-$(CONFIG_NIC7018_WDT) += nic7018_wdt.o
> diff --git a/drivers/watchdog/intel_oc_wdt.c b/drivers/watchdog/intel_oc_wdt.c
> new file mode 100644
> index 0000000000000000000000000000000000000000..7c0551106981b08f9e1d2eab8f3ddce99a2462aa
> --- /dev/null
> +++ b/drivers/watchdog/intel_oc_wdt.c
> @@ -0,0 +1,233 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Intel OC Watchdog driver
> + *
> + * Copyright (C) 2025, Siemens
> + * Author: Diogo Ivo <diogo.ivo@...mens.com>
> + */
> +
> +#define DRV_NAME	"intel_oc_wdt"
> +
> +#include <linux/acpi.h>
> +#include <linux/bits.h>
> +#include <linux/io.h>
> +#include <linux/module.h>
> +#include <linux/moduleparam.h>
> +#include <linux/platform_device.h>
> +#include <linux/watchdog.h>
> +
> +#define INTEL_OC_WDT_TOV		GENMASK(9, 0)
> +#define INTEL_OC_WDT_MIN_TOV		1
> +#define INTEL_OC_WDT_MAX_TOV		1024
> +#define INTEL_OC_WDT_DEF_TOV		60
> +
> +/*
> + * One-time writable lock bit. If set forbids
> + * modification of itself, _TOV and _EN until
> + * next reboot.
> + */
> +#define INTEL_OC_WDT_CTL_LCK		BIT(12)
> +
> +#define INTEL_OC_WDT_EN			BIT(14)
> +#define INTEL_OC_WDT_NO_ICCSURV_STS	BIT(24)
> +#define INTEL_OC_WDT_ICCSURV_STS	BIT(25)
> +#define INTEL_OC_WDT_RLD		BIT(31)
> +
> +#define INTEL_OC_WDT_STS_BITS (INTEL_OC_WDT_NO_ICCSURV_STS | \
> +			       INTEL_OC_WDT_ICCSURV_STS)
> +
> +#define INTEL_OC_WDT_CTRL_REG(wdt)	((wdt)->ctrl_res->start)
> +
> +struct intel_oc_wdt {
> +	struct watchdog_device wdd;
> +	struct resource *ctrl_res;
> +	bool locked;
> +};
> +
> +static int heartbeat;
> +module_param(heartbeat, uint, 0);
> +MODULE_PARM_DESC(heartbeat, "Watchdog heartbeats in seconds. (default="
> +		 __MODULE_STRING(WDT_HEARTBEAT) ")");
> +
> +static bool nowayout = WATCHDOG_NOWAYOUT;
> +module_param(nowayout, bool, 0);
> +MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
> +		 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
> +
> +static int intel_oc_wdt_start(struct watchdog_device *wdd)
> +{
> +	struct intel_oc_wdt *oc_wdt = watchdog_get_drvdata(wdd);
> +
> +	if (oc_wdt->locked)
> +		return 0;
> +
> +	outl(inl(INTEL_OC_WDT_CTRL_REG(oc_wdt)) | INTEL_OC_WDT_EN,
> +	     INTEL_OC_WDT_CTRL_REG(oc_wdt));
> +
> +	return 0;
> +}
> +
> +static int intel_oc_wdt_stop(struct watchdog_device *wdd)
> +{
> +	struct intel_oc_wdt *oc_wdt = watchdog_get_drvdata(wdd);
> +
> +	outl(inl(INTEL_OC_WDT_CTRL_REG(oc_wdt)) & ~INTEL_OC_WDT_EN,
> +	     INTEL_OC_WDT_CTRL_REG(oc_wdt));
> +
> +	return 0;
> +}
> +
> +static int intel_oc_wdt_ping(struct watchdog_device *wdd)
> +{
> +	struct intel_oc_wdt *oc_wdt = watchdog_get_drvdata(wdd);
> +
> +	outl(inl(INTEL_OC_WDT_CTRL_REG(oc_wdt)) | INTEL_OC_WDT_RLD,
> +	     INTEL_OC_WDT_CTRL_REG(oc_wdt));
> +
> +	return 0;
> +}
> +
> +static int intel_oc_wdt_set_timeout(struct watchdog_device *wdd,
> +				    unsigned int t)
> +{
> +	struct intel_oc_wdt *oc_wdt = watchdog_get_drvdata(wdd);
> +
> +	outl((inl(INTEL_OC_WDT_CTRL_REG(oc_wdt)) & ~INTEL_OC_WDT_TOV) | (t - 1),
> +	     INTEL_OC_WDT_CTRL_REG(oc_wdt));
> +
> +	wdd->timeout = t;
> +
> +	return 0;
> +}
> +
> +static const struct watchdog_info intel_oc_wdt_info = {
> +	.options = WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING,
> +	.identity = DRV_NAME,
> +};
> +
> +static const struct watchdog_ops intel_oc_wdt_ops = {
> +	.owner = THIS_MODULE,
> +	.start = intel_oc_wdt_start,
> +	.stop = intel_oc_wdt_stop,
> +	.ping = intel_oc_wdt_ping,
> +	.set_timeout = intel_oc_wdt_set_timeout,
> +};
> +
> +static int intel_oc_wdt_setup(struct intel_oc_wdt *oc_wdt)
> +{
> +	struct watchdog_info *info;
> +	unsigned long val;
> +
> +	val = inl(INTEL_OC_WDT_CTRL_REG(oc_wdt));
> +
> +	if (val & INTEL_OC_WDT_STS_BITS)
> +		oc_wdt->wdd.bootstatus |= WDIOF_CARDRESET;
> +
> +	oc_wdt->locked = !!(val & INTEL_OC_WDT_CTL_LCK);
> +
> +	if (val & INTEL_OC_WDT_EN) {
> +		/*
> +		 * No need to issue a ping here to "commit" the new timeout
> +		 * value to hardware as the watchdog core schedules one
> +		 * immediately when registering the watchdog.
> +		 */
> +		set_bit(WDOG_HW_RUNNING, &oc_wdt->wdd.status);
> +
> +		if (oc_wdt->locked) {
> +			info = (struct watchdog_info *)&intel_oc_wdt_info;
> +			/*
> +			 * Set nowayout unconditionally as we cannot stop
> +			 * the watchdog.
> +			 */
> +			nowayout = true;
> +			/*
> +			 * If we are locked read the current timeout value
> +			 * and inform the core we can't change it.
> +			 */
> +			oc_wdt->wdd.timeout = (val & INTEL_OC_WDT_TOV) + 1;
> +			info->options &= ~WDIOF_SETTIMEOUT;
> +
> +			dev_info(oc_wdt->wdd.parent,
> +				 "Register access locked, heartbeat fixed at: %u s\n",
> +				 oc_wdt->wdd.timeout);
> +		}
> +	} else if (oc_wdt->locked) {
> +		/*
> +		 * In case the watchdog is disabled and locked there
> +		 * is nothing we can do with it so just fail probing.
> +		 */
> +		return -EACCES;
> +	}
> +
> +	val &= ~INTEL_OC_WDT_TOV;
> +	outl(val | (oc_wdt->wdd.timeout - 1), INTEL_OC_WDT_CTRL_REG(oc_wdt));
> +
> +	return 0;
> +}
> +
> +static int intel_oc_wdt_probe(struct platform_device *pdev)
> +{
> +	struct device *dev = &pdev->dev;
> +	struct intel_oc_wdt *oc_wdt;
> +	struct watchdog_device *wdd;
> +	int ret;
> +
> +	oc_wdt = devm_kzalloc(&pdev->dev, sizeof(*oc_wdt), GFP_KERNEL);
> +	if (!oc_wdt)
> +		return -ENOMEM;
> +
> +	oc_wdt->ctrl_res = platform_get_resource(pdev, IORESOURCE_IO, 0);
> +	if (!oc_wdt->ctrl_res) {
> +		dev_err(&pdev->dev, "missing I/O resource\n");
> +		return -ENODEV;
> +	}
> +
> +	if (!devm_request_region(&pdev->dev, oc_wdt->ctrl_res->start,
> +				 resource_size(oc_wdt->ctrl_res), pdev->name)) {
> +		dev_err(dev, "resource %pR already in use, device disabled\n",
> +			oc_wdt->ctrl_res);
> +		return -EBUSY;
> +	}
> +
> +	wdd = &oc_wdt->wdd;
> +	wdd->min_timeout = INTEL_OC_WDT_MIN_TOV;
> +	wdd->max_timeout = INTEL_OC_WDT_MAX_TOV;
> +	wdd->timeout = INTEL_OC_WDT_DEF_TOV;
> +	wdd->info = &intel_oc_wdt_info;
> +	wdd->ops = &intel_oc_wdt_ops;
> +	wdd->parent = dev;
> +
> +	watchdog_init_timeout(wdd, heartbeat, dev);
> +
> +	ret = intel_oc_wdt_setup(oc_wdt);
> +	if (ret)
> +		return ret;
> +
> +	watchdog_set_drvdata(wdd, oc_wdt);
> +	watchdog_set_nowayout(wdd, nowayout);
> +	watchdog_stop_on_reboot(wdd);
> +	watchdog_stop_on_unregister(wdd);
> +
> +	return devm_watchdog_register_device(dev, wdd);
> +}
> +
> +static const struct acpi_device_id intel_oc_wdt_match[] = {
> +	{ "INT3F0D" },
> +	{ "INTC1099" },
> +	{ },
> +};
> +MODULE_DEVICE_TABLE(acpi, intel_oc_wdt_match);
> +
> +static struct platform_driver intel_oc_wdt_platform_driver = {
> +	.driver = {
> +		.name = DRV_NAME,
> +		.acpi_match_table = intel_oc_wdt_match,
> +	},
> +	.probe = intel_oc_wdt_probe,
> +};
> +
> +module_platform_driver(intel_oc_wdt_platform_driver);
> +
> +MODULE_AUTHOR("Diogo Ivo <diogo.ivo@...mens.com>");
> +MODULE_LICENSE("GPL");
> +MODULE_DESCRIPTION("Intel OC Watchdog driver");
> 

Powered by blists - more mailing lists