intel_oc_wdt.c

  1// SPDX-License-Identifier: GPL-2.0
  2/*
  3 * Intel OC Watchdog driver
  4 *
  5 * Copyright (C) 2025, Siemens
  6 * Author: Diogo Ivo <diogo.ivo@siemens.com>
  7 */
  8
  9#define DRV_NAME	"intel_oc_wdt"
 10
 11#include <linux/acpi.h>
 12#include <linux/bits.h>
 13#include <linux/io.h>
 14#include <linux/module.h>
 15#include <linux/moduleparam.h>
 16#include <linux/platform_device.h>
 17#include <linux/watchdog.h>
 18
 19#define INTEL_OC_WDT_TOV		GENMASK(9, 0)
 20#define INTEL_OC_WDT_MIN_TOV		1
 21#define INTEL_OC_WDT_MAX_TOV		1024
 22#define INTEL_OC_WDT_DEF_TOV		60
 23
 24/*
 25 * One-time writable lock bit. If set forbids
 26 * modification of itself, _TOV and _EN until
 27 * next reboot.
 28 */
 29#define INTEL_OC_WDT_CTL_LCK		BIT(12)
 30
 31#define INTEL_OC_WDT_EN			BIT(14)
 32#define INTEL_OC_WDT_NO_ICCSURV_STS	BIT(24)
 33#define INTEL_OC_WDT_ICCSURV_STS	BIT(25)
 34#define INTEL_OC_WDT_RLD		BIT(31)
 35
 36#define INTEL_OC_WDT_STS_BITS (INTEL_OC_WDT_NO_ICCSURV_STS | \
 37			       INTEL_OC_WDT_ICCSURV_STS)
 38
 39#define INTEL_OC_WDT_CTRL_REG(wdt)	((wdt)->ctrl_res->start)
 40
 41struct intel_oc_wdt {
 42	struct watchdog_device wdd;
 43	struct resource *ctrl_res;
 44	struct watchdog_info info;
 45	bool locked;
 46};
 47
 48static int heartbeat;
 49module_param(heartbeat, uint, 0);
 50MODULE_PARM_DESC(heartbeat, "Watchdog heartbeats in seconds. (default="
 51		 __MODULE_STRING(WDT_HEARTBEAT) ")");
 52
 53static bool nowayout = WATCHDOG_NOWAYOUT;
 54module_param(nowayout, bool, 0);
 55MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
 56		 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
 57
 58static int intel_oc_wdt_start(struct watchdog_device *wdd)
 59{
 60	struct intel_oc_wdt *oc_wdt = watchdog_get_drvdata(wdd);
 61
 62	if (oc_wdt->locked)
 63		return 0;
 64
 65	outl(inl(INTEL_OC_WDT_CTRL_REG(oc_wdt)) | INTEL_OC_WDT_EN,
 66	     INTEL_OC_WDT_CTRL_REG(oc_wdt));
 67
 68	return 0;
 69}
 70
 71static int intel_oc_wdt_stop(struct watchdog_device *wdd)
 72{
 73	struct intel_oc_wdt *oc_wdt = watchdog_get_drvdata(wdd);
 74
 75	outl(inl(INTEL_OC_WDT_CTRL_REG(oc_wdt)) & ~INTEL_OC_WDT_EN,
 76	     INTEL_OC_WDT_CTRL_REG(oc_wdt));
 77
 78	return 0;
 79}
 80
 81static int intel_oc_wdt_ping(struct watchdog_device *wdd)
 82{
 83	struct intel_oc_wdt *oc_wdt = watchdog_get_drvdata(wdd);
 84
 85	outl(inl(INTEL_OC_WDT_CTRL_REG(oc_wdt)) | INTEL_OC_WDT_RLD,
 86	     INTEL_OC_WDT_CTRL_REG(oc_wdt));
 87
 88	return 0;
 89}
 90
 91static int intel_oc_wdt_set_timeout(struct watchdog_device *wdd,
 92				    unsigned int t)
 93{
 94	struct intel_oc_wdt *oc_wdt = watchdog_get_drvdata(wdd);
 95
 96	outl((inl(INTEL_OC_WDT_CTRL_REG(oc_wdt)) & ~INTEL_OC_WDT_TOV) | (t - 1),
 97	     INTEL_OC_WDT_CTRL_REG(oc_wdt));
 98
 99	wdd->timeout = t;
100
101	return 0;
102}
103
104static const struct watchdog_info intel_oc_wdt_info = {
105	.options = WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING,
106	.identity = DRV_NAME,
107};
108
109static const struct watchdog_ops intel_oc_wdt_ops = {
110	.owner = THIS_MODULE,
111	.start = intel_oc_wdt_start,
112	.stop = intel_oc_wdt_stop,
113	.ping = intel_oc_wdt_ping,
114	.set_timeout = intel_oc_wdt_set_timeout,
115};
116
117static int intel_oc_wdt_setup(struct intel_oc_wdt *oc_wdt)
118{
119	unsigned long val;
120
121	val = inl(INTEL_OC_WDT_CTRL_REG(oc_wdt));
122
123	if (val & INTEL_OC_WDT_STS_BITS)
124		oc_wdt->wdd.bootstatus |= WDIOF_CARDRESET;
125
126	oc_wdt->locked = !!(val & INTEL_OC_WDT_CTL_LCK);
127
128	if (val & INTEL_OC_WDT_EN) {
129		/*
130		 * No need to issue a ping here to "commit" the new timeout
131		 * value to hardware as the watchdog core schedules one
132		 * immediately when registering the watchdog.
133		 */
134		set_bit(WDOG_HW_RUNNING, &oc_wdt->wdd.status);
135
136		if (oc_wdt->locked) {
137			/*
138			 * Set nowayout unconditionally as we cannot stop
139			 * the watchdog.
140			 */
141			nowayout = true;
142			/*
143			 * If we are locked read the current timeout value
144			 * and inform the core we can't change it.
145			 */
146			oc_wdt->wdd.timeout = (val & INTEL_OC_WDT_TOV) + 1;
147			oc_wdt->info.options &= ~WDIOF_SETTIMEOUT;
148
149			dev_info(oc_wdt->wdd.parent,
150				 "Register access locked, heartbeat fixed at: %u s\n",
151				 oc_wdt->wdd.timeout);
152		}
153	} else if (oc_wdt->locked) {
154		/*
155		 * In case the watchdog is disabled and locked there
156		 * is nothing we can do with it so just fail probing.
157		 */
158		return -EACCES;
159	}
160
161	val &= ~INTEL_OC_WDT_TOV;
162	outl(val | (oc_wdt->wdd.timeout - 1), INTEL_OC_WDT_CTRL_REG(oc_wdt));
163
164	return 0;
165}
166
167static int intel_oc_wdt_probe(struct platform_device *pdev)
168{
169	struct device *dev = &pdev->dev;
170	struct intel_oc_wdt *oc_wdt;
171	struct watchdog_device *wdd;
172	int ret;
173
174	oc_wdt = devm_kzalloc(&pdev->dev, sizeof(*oc_wdt), GFP_KERNEL);
175	if (!oc_wdt)
176		return -ENOMEM;
177
178	oc_wdt->ctrl_res = platform_get_resource(pdev, IORESOURCE_IO, 0);
179	if (!oc_wdt->ctrl_res) {
180		dev_err(&pdev->dev, "missing I/O resource\n");
181		return -ENODEV;
182	}
183
184	if (!devm_request_region(&pdev->dev, oc_wdt->ctrl_res->start,
185				 resource_size(oc_wdt->ctrl_res), pdev->name)) {
186		dev_err(dev, "resource %pR already in use, device disabled\n",
187			oc_wdt->ctrl_res);
188		return -EBUSY;
189	}
190
191	wdd = &oc_wdt->wdd;
192	wdd->min_timeout = INTEL_OC_WDT_MIN_TOV;
193	wdd->max_timeout = INTEL_OC_WDT_MAX_TOV;
194	wdd->timeout = INTEL_OC_WDT_DEF_TOV;
195	oc_wdt->info = intel_oc_wdt_info;
196	wdd->info = &oc_wdt->info;
197	wdd->ops = &intel_oc_wdt_ops;
198	wdd->parent = dev;
199
200	watchdog_init_timeout(wdd, heartbeat, dev);
201
202	ret = intel_oc_wdt_setup(oc_wdt);
203	if (ret)
204		return ret;
205
206	watchdog_set_drvdata(wdd, oc_wdt);
207	watchdog_set_nowayout(wdd, nowayout);
208	watchdog_stop_on_reboot(wdd);
209	watchdog_stop_on_unregister(wdd);
210
211	return devm_watchdog_register_device(dev, wdd);
212}
213
214static const struct acpi_device_id intel_oc_wdt_match[] = {
215	{ "INT3F0D" },
216	{ "INTC1099" },
217	{ },
218};
219MODULE_DEVICE_TABLE(acpi, intel_oc_wdt_match);
220
221static struct platform_driver intel_oc_wdt_platform_driver = {
222	.driver = {
223		.name = DRV_NAME,
224		.acpi_match_table = intel_oc_wdt_match,
225	},
226	.probe = intel_oc_wdt_probe,
227};
228
229module_platform_driver(intel_oc_wdt_platform_driver);
230
231MODULE_AUTHOR("Diogo Ivo <diogo.ivo@siemens.com>");
232MODULE_LICENSE("GPL");
233MODULE_DESCRIPTION("Intel OC Watchdog driver");