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// SPDX-License-Identifier: GPL-2.0
/*
* Intel OC Watchdog driver
*
* Copyright (C) 2025, Siemens
* Author: Diogo Ivo <diogo.ivo@siemens.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@siemens.com>");
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("Intel OC Watchdog driver");
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