1// SPDX-License-Identifier: GPL-2.0-or-later
  2/*
  3 * Copyright (c) 2022 International Business Machines, Inc.
  4 */
  5
  6#include <linux/bitops.h>
  7#include <linux/kernel.h>
  8#include <linux/limits.h>
  9#include <linux/math.h>
 10#include <linux/mod_devicetable.h>
 11#include <linux/module.h>
 12#include <linux/moduleparam.h>
 13#include <linux/platform_device.h>
 14#include <linux/time64.h>
 15#include <linux/watchdog.h>
 16
 17#define DRV_NAME "pseries-wdt"
 18
 19/*
 20 * H_WATCHDOG Input
 21 *
 22 * R4: "flags":
 23 *
 24 *         Bits 48-55: "operation"
 25 */
 26#define PSERIES_WDTF_OP_START	0x100UL		/* start timer */
 27#define PSERIES_WDTF_OP_STOP	0x200UL		/* stop timer */
 28#define PSERIES_WDTF_OP_QUERY	0x300UL		/* query timer capabilities */
 29
 30/*
 31 *         Bits 56-63: "timeoutAction" (for "Start Watchdog" only)
 32 */
 33#define PSERIES_WDTF_ACTION_HARD_POWEROFF	0x1UL	/* poweroff */
 34#define PSERIES_WDTF_ACTION_HARD_RESTART	0x2UL	/* restart */
 35#define PSERIES_WDTF_ACTION_DUMP_RESTART	0x3UL	/* dump + restart */
 36
 37/*
 38 * H_WATCHDOG Output
 39 *
 40 * R3: Return code
 41 *
 42 *     H_SUCCESS    The operation completed.
 43 *
 44 *     H_BUSY	    The hypervisor is too busy; retry the operation.
 45 *
 46 *     H_PARAMETER  The given "flags" are somehow invalid.  Either the
 47 *                  "operation" or "timeoutAction" is invalid, or a
 48 *                  reserved bit is set.
 49 *
 50 *     H_P2         The given "watchdogNumber" is zero or exceeds the
 51 *                  supported maximum value.
 52 *
 53 *     H_P3         The given "timeoutInMs" is below the supported
 54 *                  minimum value.
 55 *
 56 *     H_NOOP       The given "watchdogNumber" is already stopped.
 57 *
 58 *     H_HARDWARE   The operation failed for ineffable reasons.
 59 *
 60 *     H_FUNCTION   The H_WATCHDOG hypercall is not supported by this
 61 *                  hypervisor.
 62 *
 63 * R4:
 64 *
 65 * - For the "Query Watchdog Capabilities" operation, a 64-bit
 66 *   structure:
 67 */
 68#define PSERIES_WDTQ_MIN_TIMEOUT(cap)	(((cap) >> 48) & 0xffff)
 69#define PSERIES_WDTQ_MAX_NUMBER(cap)	(((cap) >> 32) & 0xffff)
 70
 71static const unsigned long pseries_wdt_action[] = {
 72	[0] = PSERIES_WDTF_ACTION_HARD_POWEROFF,
 73	[1] = PSERIES_WDTF_ACTION_HARD_RESTART,
 74	[2] = PSERIES_WDTF_ACTION_DUMP_RESTART,
 75};
 76
 77#define WATCHDOG_ACTION 1
 78static unsigned int action = WATCHDOG_ACTION;
 79module_param(action, uint, 0444);
 80MODULE_PARM_DESC(action, "Action taken when watchdog expires (default="
 81		 __MODULE_STRING(WATCHDOG_ACTION) ")");
 82
 83static bool nowayout = WATCHDOG_NOWAYOUT;
 84module_param(nowayout, bool, 0444);
 85MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
 86		 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
 87
 88#define WATCHDOG_TIMEOUT 60
 89static unsigned int timeout = WATCHDOG_TIMEOUT;
 90module_param(timeout, uint, 0444);
 91MODULE_PARM_DESC(timeout, "Initial watchdog timeout in seconds (default="
 92		 __MODULE_STRING(WATCHDOG_TIMEOUT) ")");
 93
 94struct pseries_wdt {
 95	struct watchdog_device wd;
 96	unsigned long action;
 97	unsigned long num;		/* Watchdog numbers are 1-based */
 98};
 99
100static int pseries_wdt_start(struct watchdog_device *wdd)
101{
102	struct pseries_wdt *pw = watchdog_get_drvdata(wdd);
103	struct device *dev = wdd->parent;
104	unsigned long flags, msecs;
105	long rc;
106
107	flags = pw->action | PSERIES_WDTF_OP_START;
108	msecs = wdd->timeout * MSEC_PER_SEC;
109	rc = plpar_hcall_norets(H_WATCHDOG, flags, pw->num, msecs);
110	if (rc != H_SUCCESS) {
111		dev_crit(dev, "H_WATCHDOG: %ld: failed to start timer %lu",
112			 rc, pw->num);
113		return -EIO;
114	}
115	return 0;
116}
117
118static int pseries_wdt_stop(struct watchdog_device *wdd)
119{
120	struct pseries_wdt *pw = watchdog_get_drvdata(wdd);
121	struct device *dev = wdd->parent;
122	long rc;
123
124	rc = plpar_hcall_norets(H_WATCHDOG, PSERIES_WDTF_OP_STOP, pw->num);
125	if (rc != H_SUCCESS && rc != H_NOOP) {
126		dev_crit(dev, "H_WATCHDOG: %ld: failed to stop timer %lu",
127			 rc, pw->num);
128		return -EIO;
129	}
130	return 0;
131}
132
133static struct watchdog_info pseries_wdt_info = {
134	.identity = DRV_NAME,
135	.options = WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE | WDIOF_SETTIMEOUT
136	    | WDIOF_PRETIMEOUT,
137};
138
139static const struct watchdog_ops pseries_wdt_ops = {
140	.owner = THIS_MODULE,
141	.start = pseries_wdt_start,
142	.stop = pseries_wdt_stop,
143};
144
145static int pseries_wdt_probe(struct platform_device *pdev)
146{
147	unsigned long ret[PLPAR_HCALL_BUFSIZE] = { 0 };
148	struct pseries_wdt *pw;
149	unsigned long cap;
150	long msecs, rc;
151	int err;
152
153	rc = plpar_hcall(H_WATCHDOG, ret, PSERIES_WDTF_OP_QUERY);
154	if (rc == H_FUNCTION)
155		return -ENODEV;
156	if (rc != H_SUCCESS)
157		return -EIO;
158	cap = ret[0];
159
160	pw = devm_kzalloc(&pdev->dev, sizeof(*pw), GFP_KERNEL);
161	if (!pw)
162		return -ENOMEM;
163
164	/*
165	 * Assume watchdogNumber 1 for now.  If we ever support
166	 * multiple timers we will need to devise a way to choose a
167	 * distinct watchdogNumber for each platform device at device
168	 * registration time.
169	 */
170	pw->num = 1;
171	if (PSERIES_WDTQ_MAX_NUMBER(cap) < pw->num)
172		return -ENODEV;
173
174	if (action >= ARRAY_SIZE(pseries_wdt_action))
175		return -EINVAL;
176	pw->action = pseries_wdt_action[action];
177
178	pw->wd.parent = &pdev->dev;
179	pw->wd.info = &pseries_wdt_info;
180	pw->wd.ops = &pseries_wdt_ops;
181	msecs = PSERIES_WDTQ_MIN_TIMEOUT(cap);
182	pw->wd.min_timeout = DIV_ROUND_UP(msecs, MSEC_PER_SEC);
183	pw->wd.max_timeout = UINT_MAX / 1000;	/* from linux/watchdog.h */
184	pw->wd.timeout = timeout;
185	if (watchdog_init_timeout(&pw->wd, 0, NULL))
186		return -EINVAL;
187	watchdog_set_nowayout(&pw->wd, nowayout);
188	watchdog_stop_on_reboot(&pw->wd);
189	watchdog_stop_on_unregister(&pw->wd);
190	watchdog_set_drvdata(&pw->wd, pw);
191
192	err = devm_watchdog_register_device(&pdev->dev, &pw->wd);
193	if (err)
194		return err;
195
196	platform_set_drvdata(pdev, &pw->wd);
197
198	return 0;
199}
200
201static int pseries_wdt_suspend(struct platform_device *pdev, pm_message_t state)
202{
203	struct watchdog_device *wd = platform_get_drvdata(pdev);
204
205	if (watchdog_active(wd))
206		return pseries_wdt_stop(wd);
207	return 0;
208}
209
210static int pseries_wdt_resume(struct platform_device *pdev)
211{
212	struct watchdog_device *wd = platform_get_drvdata(pdev);
213
214	if (watchdog_active(wd))
215		return pseries_wdt_start(wd);
216	return 0;
217}
218
219static const struct platform_device_id pseries_wdt_id[] = {
220	{ .name = "pseries-wdt" },
221	{}
222};
223MODULE_DEVICE_TABLE(platform, pseries_wdt_id);
224
225static struct platform_driver pseries_wdt_driver = {
226	.driver = {
227		.name = DRV_NAME,
228	},
229	.id_table = pseries_wdt_id,
230	.probe = pseries_wdt_probe,
231	.resume = pseries_wdt_resume,
232	.suspend = pseries_wdt_suspend,
233};
234module_platform_driver(pseries_wdt_driver);
235
236MODULE_AUTHOR("Alexey Kardashevskiy");
237MODULE_AUTHOR("Scott Cheloha");
238MODULE_DESCRIPTION("POWER Architecture Platform Watchdog Driver");
239MODULE_LICENSE("GPL");