Message-ID: <fea41656-ca80-491f-b84b-d118b35b5f72@roeck-us.net>
Date: Tue, 11 Mar 2025 07:10:46 -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] watchdog: Add driver for Intel OC WDT

On 3/11/25 06:18, 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>
> ---
>   drivers/acpi/acpi_pnp.c         |   2 +
>   drivers/watchdog/Kconfig        |  11 ++
>   drivers/watchdog/Makefile       |   1 +
>   drivers/watchdog/intel_oc_wdt.c | 235 ++++++++++++++++++++++++++++++++++++++++
>   4 files changed, 249 insertions(+)
> 
> diff --git a/drivers/acpi/acpi_pnp.c b/drivers/acpi/acpi_pnp.c
> index 01abf26764b00c86f938dea2ed138424f041f880..3f5a1840f573303c71f5d579e32963a5b29d2587 100644
> --- a/drivers/acpi/acpi_pnp.c
> +++ b/drivers/acpi/acpi_pnp.c
> @@ -355,8 +355,10 @@ static bool acpi_pnp_match(const char *idstr, const struct acpi_device_id **matc
>    * device represented by it.
>    */
>   static const struct acpi_device_id acpi_nonpnp_device_ids[] = {
> +	{"INT3F0D"},
>   	{"INTC1080"},
>   	{"INTC1081"},
> +	{"INTC1099"},
>   	{""},
>   };

This needs to be a separate patch.

>   
> diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
> index f81705f8539aa0b12d156a86aae521aa40b4527d..16e6df441bb344c0f91b40bd76b6322ad3016e72 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 && ACPI
> +	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..0a2df3440024090f7e342fe7da895a7930ac09b2
> --- /dev/null
> +++ b/drivers/watchdog/intel_oc_wdt.c
> @@ -0,0 +1,235 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Intel OC Watchdog driver
> + *
> + * Copyright (C) 2025, Siemens SA
> + * 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
> +
> +/*
> + * 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;
> +};
> +
> +#define WDT_HEARTBEAT			60
> +static int heartbeat = WDT_HEARTBEAT;

Normally this is set to 0 and the default timeout is initialized together
with min_timeout and max_timeout. This lets the watchdog core override it
with devicetree data (if that is available).

> +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 and read the current timeout.
> +			 */

But the timeout is read below ? Do you mean "change the current timeout" ?

> +			nowayout = true;
> +
> +			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, "I/O address 0x%04llx already in use, device disabled\n",
> +		       (u64)(oc_wdt->ctrl_res->start));

Use %pa or %pR/%pr, and watch out for multi-line alignment.

Guenter

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