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 
71 static 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
78 static unsigned int action = WATCHDOG_ACTION;
79 module_param(action, uint, 0444);
80 MODULE_PARM_DESC(action, "Action taken when watchdog expires (default="
81 		 __MODULE_STRING(WATCHDOG_ACTION) ")");
82 
83 static bool nowayout = WATCHDOG_NOWAYOUT;
84 module_param(nowayout, bool, 0444);
85 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
86 		 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
87 
88 #define WATCHDOG_TIMEOUT 60
89 static unsigned int timeout = WATCHDOG_TIMEOUT;
90 module_param(timeout, uint, 0444);
91 MODULE_PARM_DESC(timeout, "Initial watchdog timeout in seconds (default="
92 		 __MODULE_STRING(WATCHDOG_TIMEOUT) ")");
93 
94 struct pseries_wdt {
95 	struct watchdog_device wd;
96 	unsigned long action;
97 	unsigned long num;		/* Watchdog numbers are 1-based */
98 };
99 
pseries_wdt_start(struct watchdog_device * wdd)100 static 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 
pseries_wdt_stop(struct watchdog_device * wdd)118 static 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 
133 static struct watchdog_info pseries_wdt_info = {
134 	.identity = DRV_NAME,
135 	.options = WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE | WDIOF_SETTIMEOUT
136 	    | WDIOF_PRETIMEOUT,
137 };
138 
139 static const struct watchdog_ops pseries_wdt_ops = {
140 	.owner = THIS_MODULE,
141 	.start = pseries_wdt_start,
142 	.stop = pseries_wdt_stop,
143 };
144 
pseries_wdt_probe(struct platform_device * pdev)145 static 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 
pseries_wdt_suspend(struct platform_device * pdev,pm_message_t state)201 static 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 
pseries_wdt_resume(struct platform_device * pdev)210 static 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 
219 static const struct platform_device_id pseries_wdt_id[] = {
220 	{ .name = "pseries-wdt" },
221 	{}
222 };
223 MODULE_DEVICE_TABLE(platform, pseries_wdt_id);
224 
225 static 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 };
234 module_platform_driver(pseries_wdt_driver);
235 
236 MODULE_AUTHOR("Alexey Kardashevskiy");
237 MODULE_AUTHOR("Scott Cheloha");
238 MODULE_DESCRIPTION("POWER Architecture Platform Watchdog Driver");
239 MODULE_LICENSE("GPL");
240