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