1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * Kontron PLD watchdog driver
4 *
5 * Copyright (c) 2010-2013 Kontron Europe GmbH
6 * Author: Michael Brunner <michael.brunner@kontron.com>
7 *
8 * Note: From the PLD watchdog point of view timeout and pretimeout are
9 * defined differently than in the kernel.
10 * First the pretimeout stage runs out before the timeout stage gets
11 * active.
12 *
13 * Kernel/API: P-----| pretimeout
14 * |-----------------------T timeout
15 * Watchdog: |-----------------P pretimeout_stage
16 * |-----T timeout_stage
17 */
18
19 #include <linux/module.h>
20 #include <linux/moduleparam.h>
21 #include <linux/uaccess.h>
22 #include <linux/watchdog.h>
23 #include <linux/platform_device.h>
24 #include <linux/mfd/kempld.h>
25
26 #define KEMPLD_WDT_STAGE_TIMEOUT(x) (0x1b + (x) * 4)
27 #define KEMPLD_WDT_STAGE_CFG(x) (0x18 + (x))
28 #define STAGE_CFG_GET_PRESCALER(x) (((x) & 0x30) >> 4)
29 #define STAGE_CFG_SET_PRESCALER(x) (((x) & 0x3) << 4)
30 #define STAGE_CFG_PRESCALER_MASK 0x30
31 #define STAGE_CFG_ACTION_MASK 0x7
32 #define STAGE_CFG_ASSERT (1 << 3)
33
34 #define KEMPLD_WDT_MAX_STAGES 2
35 #define KEMPLD_WDT_KICK 0x16
36 #define KEMPLD_WDT_CFG 0x17
37 #define KEMPLD_WDT_CFG_ENABLE 0x10
38 #define KEMPLD_WDT_CFG_ENABLE_LOCK 0x8
39 #define KEMPLD_WDT_CFG_GLOBAL_LOCK 0x80
40
41 enum {
42 ACTION_NONE = 0,
43 ACTION_RESET,
44 ACTION_NMI,
45 ACTION_SMI,
46 ACTION_SCI,
47 ACTION_DELAY,
48 };
49
50 enum {
51 STAGE_TIMEOUT = 0,
52 STAGE_PRETIMEOUT,
53 };
54
55 enum {
56 PRESCALER_21 = 0,
57 PRESCALER_17,
58 PRESCALER_12,
59 };
60
61 static const u32 kempld_prescaler[] = {
62 [PRESCALER_21] = (1 << 21) - 1,
63 [PRESCALER_17] = (1 << 17) - 1,
64 [PRESCALER_12] = (1 << 12) - 1,
65 0,
66 };
67
68 struct kempld_wdt_stage {
69 unsigned int id;
70 u32 mask;
71 };
72
73 struct kempld_wdt_data {
74 struct kempld_device_data *pld;
75 struct watchdog_device wdd;
76 unsigned int pretimeout;
77 struct kempld_wdt_stage stage[KEMPLD_WDT_MAX_STAGES];
78 u8 pm_status_store;
79 };
80
81 #define DEFAULT_TIMEOUT 30 /* seconds */
82 #define DEFAULT_PRETIMEOUT 0
83
84 static unsigned int timeout = DEFAULT_TIMEOUT;
85 module_param(timeout, uint, 0);
86 MODULE_PARM_DESC(timeout,
87 "Watchdog timeout in seconds. (>=0, default="
88 __MODULE_STRING(DEFAULT_TIMEOUT) ")");
89
90 static unsigned int pretimeout = DEFAULT_PRETIMEOUT;
91 module_param(pretimeout, uint, 0);
92 MODULE_PARM_DESC(pretimeout,
93 "Watchdog pretimeout in seconds. (>=0, default="
94 __MODULE_STRING(DEFAULT_PRETIMEOUT) ")");
95
96 static bool nowayout = WATCHDOG_NOWAYOUT;
97 module_param(nowayout, bool, 0);
98 MODULE_PARM_DESC(nowayout,
99 "Watchdog cannot be stopped once started (default="
100 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
101
kempld_wdt_set_stage_action(struct kempld_wdt_data * wdt_data,struct kempld_wdt_stage * stage,u8 action)102 static int kempld_wdt_set_stage_action(struct kempld_wdt_data *wdt_data,
103 struct kempld_wdt_stage *stage,
104 u8 action)
105 {
106 struct kempld_device_data *pld = wdt_data->pld;
107 u8 stage_cfg;
108
109 if (!stage || !stage->mask)
110 return -EINVAL;
111
112 kempld_get_mutex(pld);
113 stage_cfg = kempld_read8(pld, KEMPLD_WDT_STAGE_CFG(stage->id));
114 stage_cfg &= ~STAGE_CFG_ACTION_MASK;
115 stage_cfg |= (action & STAGE_CFG_ACTION_MASK);
116
117 if (action == ACTION_RESET)
118 stage_cfg |= STAGE_CFG_ASSERT;
119 else
120 stage_cfg &= ~STAGE_CFG_ASSERT;
121
122 kempld_write8(pld, KEMPLD_WDT_STAGE_CFG(stage->id), stage_cfg);
123 kempld_release_mutex(pld);
124
125 return 0;
126 }
127
kempld_wdt_set_stage_timeout(struct kempld_wdt_data * wdt_data,struct kempld_wdt_stage * stage,unsigned int timeout)128 static int kempld_wdt_set_stage_timeout(struct kempld_wdt_data *wdt_data,
129 struct kempld_wdt_stage *stage,
130 unsigned int timeout)
131 {
132 struct kempld_device_data *pld = wdt_data->pld;
133 u32 prescaler;
134 u64 stage_timeout64;
135 u32 stage_timeout;
136 u32 remainder;
137 u8 stage_cfg;
138
139 prescaler = kempld_prescaler[PRESCALER_21];
140
141 if (!stage)
142 return -EINVAL;
143
144 stage_timeout64 = (u64)timeout * pld->pld_clock;
145 remainder = do_div(stage_timeout64, prescaler);
146 if (remainder)
147 stage_timeout64++;
148
149 if (stage_timeout64 > stage->mask)
150 return -EINVAL;
151
152 stage_timeout = stage_timeout64 & stage->mask;
153
154 kempld_get_mutex(pld);
155 stage_cfg = kempld_read8(pld, KEMPLD_WDT_STAGE_CFG(stage->id));
156 stage_cfg &= ~STAGE_CFG_PRESCALER_MASK;
157 stage_cfg |= STAGE_CFG_SET_PRESCALER(PRESCALER_21);
158 kempld_write8(pld, KEMPLD_WDT_STAGE_CFG(stage->id), stage_cfg);
159 kempld_write32(pld, KEMPLD_WDT_STAGE_TIMEOUT(stage->id),
160 stage_timeout);
161 kempld_release_mutex(pld);
162
163 return 0;
164 }
165
166 /*
167 * kempld_get_mutex must be called prior to calling this function.
168 */
kempld_wdt_get_timeout(struct kempld_wdt_data * wdt_data,struct kempld_wdt_stage * stage)169 static unsigned int kempld_wdt_get_timeout(struct kempld_wdt_data *wdt_data,
170 struct kempld_wdt_stage *stage)
171 {
172 struct kempld_device_data *pld = wdt_data->pld;
173 unsigned int timeout;
174 u64 stage_timeout;
175 u32 prescaler;
176 u32 remainder;
177 u8 stage_cfg;
178
179 if (!stage->mask)
180 return 0;
181
182 stage_cfg = kempld_read8(pld, KEMPLD_WDT_STAGE_CFG(stage->id));
183 stage_timeout = kempld_read32(pld, KEMPLD_WDT_STAGE_TIMEOUT(stage->id));
184 prescaler = kempld_prescaler[STAGE_CFG_GET_PRESCALER(stage_cfg)];
185
186 stage_timeout = (stage_timeout & stage->mask) * prescaler;
187 remainder = do_div(stage_timeout, pld->pld_clock);
188 if (remainder)
189 stage_timeout++;
190
191 timeout = stage_timeout;
192 WARN_ON_ONCE(timeout != stage_timeout);
193
194 return timeout;
195 }
196
kempld_wdt_set_timeout(struct watchdog_device * wdd,unsigned int timeout)197 static int kempld_wdt_set_timeout(struct watchdog_device *wdd,
198 unsigned int timeout)
199 {
200 struct kempld_wdt_data *wdt_data = watchdog_get_drvdata(wdd);
201 struct kempld_wdt_stage *pretimeout_stage;
202 struct kempld_wdt_stage *timeout_stage;
203 int ret;
204
205 timeout_stage = &wdt_data->stage[STAGE_TIMEOUT];
206 pretimeout_stage = &wdt_data->stage[STAGE_PRETIMEOUT];
207
208 if (pretimeout_stage->mask && wdt_data->pretimeout > 0)
209 timeout = wdt_data->pretimeout;
210
211 ret = kempld_wdt_set_stage_action(wdt_data, timeout_stage,
212 ACTION_RESET);
213 if (ret)
214 return ret;
215 ret = kempld_wdt_set_stage_timeout(wdt_data, timeout_stage,
216 timeout);
217 if (ret)
218 return ret;
219
220 wdd->timeout = timeout;
221 return 0;
222 }
223
kempld_wdt_set_pretimeout(struct watchdog_device * wdd,unsigned int pretimeout)224 static int kempld_wdt_set_pretimeout(struct watchdog_device *wdd,
225 unsigned int pretimeout)
226 {
227 struct kempld_wdt_data *wdt_data = watchdog_get_drvdata(wdd);
228 struct kempld_wdt_stage *pretimeout_stage;
229 u8 action = ACTION_NONE;
230 int ret;
231
232 pretimeout_stage = &wdt_data->stage[STAGE_PRETIMEOUT];
233
234 if (!pretimeout_stage->mask)
235 return -ENXIO;
236
237 if (pretimeout > wdd->timeout)
238 return -EINVAL;
239
240 if (pretimeout > 0)
241 action = ACTION_NMI;
242
243 ret = kempld_wdt_set_stage_action(wdt_data, pretimeout_stage,
244 action);
245 if (ret)
246 return ret;
247 ret = kempld_wdt_set_stage_timeout(wdt_data, pretimeout_stage,
248 wdd->timeout - pretimeout);
249 if (ret)
250 return ret;
251
252 wdt_data->pretimeout = pretimeout;
253 return 0;
254 }
255
kempld_wdt_update_timeouts(struct kempld_wdt_data * wdt_data)256 static void kempld_wdt_update_timeouts(struct kempld_wdt_data *wdt_data)
257 {
258 struct kempld_device_data *pld = wdt_data->pld;
259 struct kempld_wdt_stage *pretimeout_stage;
260 struct kempld_wdt_stage *timeout_stage;
261 unsigned int pretimeout, timeout;
262
263 pretimeout_stage = &wdt_data->stage[STAGE_PRETIMEOUT];
264 timeout_stage = &wdt_data->stage[STAGE_TIMEOUT];
265
266 kempld_get_mutex(pld);
267 pretimeout = kempld_wdt_get_timeout(wdt_data, pretimeout_stage);
268 timeout = kempld_wdt_get_timeout(wdt_data, timeout_stage);
269 kempld_release_mutex(pld);
270
271 if (pretimeout)
272 wdt_data->pretimeout = timeout;
273 else
274 wdt_data->pretimeout = 0;
275
276 wdt_data->wdd.timeout = pretimeout + timeout;
277 }
278
kempld_wdt_start(struct watchdog_device * wdd)279 static int kempld_wdt_start(struct watchdog_device *wdd)
280 {
281 struct kempld_wdt_data *wdt_data = watchdog_get_drvdata(wdd);
282 struct kempld_device_data *pld = wdt_data->pld;
283 u8 status;
284 int ret;
285
286 ret = kempld_wdt_set_timeout(wdd, wdd->timeout);
287 if (ret)
288 return ret;
289
290 kempld_get_mutex(pld);
291 status = kempld_read8(pld, KEMPLD_WDT_CFG);
292 status |= KEMPLD_WDT_CFG_ENABLE;
293 kempld_write8(pld, KEMPLD_WDT_CFG, status);
294 status = kempld_read8(pld, KEMPLD_WDT_CFG);
295 kempld_release_mutex(pld);
296
297 /* Check if the watchdog was enabled */
298 if (!(status & KEMPLD_WDT_CFG_ENABLE))
299 return -EACCES;
300
301 return 0;
302 }
303
kempld_wdt_stop(struct watchdog_device * wdd)304 static int kempld_wdt_stop(struct watchdog_device *wdd)
305 {
306 struct kempld_wdt_data *wdt_data = watchdog_get_drvdata(wdd);
307 struct kempld_device_data *pld = wdt_data->pld;
308 u8 status;
309
310 kempld_get_mutex(pld);
311 status = kempld_read8(pld, KEMPLD_WDT_CFG);
312 status &= ~KEMPLD_WDT_CFG_ENABLE;
313 kempld_write8(pld, KEMPLD_WDT_CFG, status);
314 status = kempld_read8(pld, KEMPLD_WDT_CFG);
315 kempld_release_mutex(pld);
316
317 /* Check if the watchdog was disabled */
318 if (status & KEMPLD_WDT_CFG_ENABLE)
319 return -EACCES;
320
321 return 0;
322 }
323
kempld_wdt_keepalive(struct watchdog_device * wdd)324 static int kempld_wdt_keepalive(struct watchdog_device *wdd)
325 {
326 struct kempld_wdt_data *wdt_data = watchdog_get_drvdata(wdd);
327 struct kempld_device_data *pld = wdt_data->pld;
328
329 kempld_get_mutex(pld);
330 kempld_write8(pld, KEMPLD_WDT_KICK, 'K');
331 kempld_release_mutex(pld);
332
333 return 0;
334 }
335
kempld_wdt_ioctl(struct watchdog_device * wdd,unsigned int cmd,unsigned long arg)336 static long kempld_wdt_ioctl(struct watchdog_device *wdd, unsigned int cmd,
337 unsigned long arg)
338 {
339 struct kempld_wdt_data *wdt_data = watchdog_get_drvdata(wdd);
340 void __user *argp = (void __user *)arg;
341 int ret = -ENOIOCTLCMD;
342 int __user *p = argp;
343 int new_value;
344
345 switch (cmd) {
346 case WDIOC_SETPRETIMEOUT:
347 if (get_user(new_value, p))
348 return -EFAULT;
349 ret = kempld_wdt_set_pretimeout(wdd, new_value);
350 if (ret)
351 return ret;
352 ret = kempld_wdt_keepalive(wdd);
353 break;
354 case WDIOC_GETPRETIMEOUT:
355 ret = put_user(wdt_data->pretimeout, (int __user *)arg);
356 break;
357 }
358
359 return ret;
360 }
361
kempld_wdt_probe_stages(struct watchdog_device * wdd)362 static int kempld_wdt_probe_stages(struct watchdog_device *wdd)
363 {
364 struct kempld_wdt_data *wdt_data = watchdog_get_drvdata(wdd);
365 struct kempld_device_data *pld = wdt_data->pld;
366 struct kempld_wdt_stage *pretimeout_stage;
367 struct kempld_wdt_stage *timeout_stage;
368 u8 index, data, data_orig;
369 u32 mask;
370 int i, j;
371
372 pretimeout_stage = &wdt_data->stage[STAGE_PRETIMEOUT];
373 timeout_stage = &wdt_data->stage[STAGE_TIMEOUT];
374
375 pretimeout_stage->mask = 0;
376 timeout_stage->mask = 0;
377
378 for (i = 0; i < 3; i++) {
379 index = KEMPLD_WDT_STAGE_TIMEOUT(i);
380 mask = 0;
381
382 kempld_get_mutex(pld);
383 /* Probe each byte individually. */
384 for (j = 0; j < 4; j++) {
385 data_orig = kempld_read8(pld, index + j);
386 kempld_write8(pld, index + j, 0x00);
387 data = kempld_read8(pld, index + j);
388 /* A failed write means this byte is reserved */
389 if (data != 0x00)
390 break;
391 kempld_write8(pld, index + j, data_orig);
392 mask |= 0xff << (j * 8);
393 }
394 kempld_release_mutex(pld);
395
396 /* Assign available stages to timeout and pretimeout */
397 if (!timeout_stage->mask) {
398 timeout_stage->mask = mask;
399 timeout_stage->id = i;
400 } else {
401 if (pld->feature_mask & KEMPLD_FEATURE_BIT_NMI) {
402 pretimeout_stage->mask = timeout_stage->mask;
403 timeout_stage->mask = mask;
404 pretimeout_stage->id = timeout_stage->id;
405 timeout_stage->id = i;
406 }
407 break;
408 }
409 }
410
411 if (!timeout_stage->mask)
412 return -ENODEV;
413
414 return 0;
415 }
416
417 static const struct watchdog_info kempld_wdt_info = {
418 .identity = "KEMPLD Watchdog",
419 .options = WDIOF_SETTIMEOUT |
420 WDIOF_KEEPALIVEPING |
421 WDIOF_MAGICCLOSE |
422 WDIOF_PRETIMEOUT
423 };
424
425 static const struct watchdog_ops kempld_wdt_ops = {
426 .owner = THIS_MODULE,
427 .start = kempld_wdt_start,
428 .stop = kempld_wdt_stop,
429 .ping = kempld_wdt_keepalive,
430 .set_timeout = kempld_wdt_set_timeout,
431 .ioctl = kempld_wdt_ioctl,
432 };
433
kempld_wdt_probe(struct platform_device * pdev)434 static int kempld_wdt_probe(struct platform_device *pdev)
435 {
436 struct kempld_device_data *pld = dev_get_drvdata(pdev->dev.parent);
437 struct kempld_wdt_data *wdt_data;
438 struct device *dev = &pdev->dev;
439 struct watchdog_device *wdd;
440 u8 status;
441 int ret = 0;
442
443 wdt_data = devm_kzalloc(dev, sizeof(*wdt_data), GFP_KERNEL);
444 if (!wdt_data)
445 return -ENOMEM;
446
447 wdt_data->pld = pld;
448 wdd = &wdt_data->wdd;
449 wdd->parent = dev;
450
451 kempld_get_mutex(pld);
452 status = kempld_read8(pld, KEMPLD_WDT_CFG);
453 kempld_release_mutex(pld);
454
455 /* Enable nowayout if watchdog is already locked */
456 if (status & (KEMPLD_WDT_CFG_ENABLE_LOCK |
457 KEMPLD_WDT_CFG_GLOBAL_LOCK)) {
458 if (!nowayout)
459 dev_warn(dev,
460 "Forcing nowayout - watchdog lock enabled!\n");
461 nowayout = true;
462 }
463
464 wdd->info = &kempld_wdt_info;
465 wdd->ops = &kempld_wdt_ops;
466
467 watchdog_set_drvdata(wdd, wdt_data);
468 watchdog_set_nowayout(wdd, nowayout);
469
470 ret = kempld_wdt_probe_stages(wdd);
471 if (ret)
472 return ret;
473
474 kempld_wdt_set_timeout(wdd, timeout);
475 kempld_wdt_set_pretimeout(wdd, pretimeout);
476
477 /* Check if watchdog is already enabled */
478 if (status & KEMPLD_WDT_CFG_ENABLE) {
479 /* Get current watchdog settings */
480 kempld_wdt_update_timeouts(wdt_data);
481 dev_info(dev, "Watchdog was already enabled\n");
482 }
483
484 platform_set_drvdata(pdev, wdt_data);
485 watchdog_stop_on_reboot(wdd);
486 watchdog_stop_on_unregister(wdd);
487 ret = devm_watchdog_register_device(dev, wdd);
488 if (ret)
489 return ret;
490
491 dev_info(dev, "Watchdog registered with %ds timeout\n", wdd->timeout);
492
493 return 0;
494 }
495
496 /* Disable watchdog if it is active during suspend */
kempld_wdt_suspend(struct platform_device * pdev,pm_message_t message)497 static int kempld_wdt_suspend(struct platform_device *pdev,
498 pm_message_t message)
499 {
500 struct kempld_wdt_data *wdt_data = platform_get_drvdata(pdev);
501 struct kempld_device_data *pld = wdt_data->pld;
502 struct watchdog_device *wdd = &wdt_data->wdd;
503
504 kempld_get_mutex(pld);
505 wdt_data->pm_status_store = kempld_read8(pld, KEMPLD_WDT_CFG);
506 kempld_release_mutex(pld);
507
508 kempld_wdt_update_timeouts(wdt_data);
509
510 if (wdt_data->pm_status_store & KEMPLD_WDT_CFG_ENABLE)
511 return kempld_wdt_stop(wdd);
512
513 return 0;
514 }
515
516 /* Enable watchdog and configure it if necessary */
kempld_wdt_resume(struct platform_device * pdev)517 static int kempld_wdt_resume(struct platform_device *pdev)
518 {
519 struct kempld_wdt_data *wdt_data = platform_get_drvdata(pdev);
520 struct watchdog_device *wdd = &wdt_data->wdd;
521
522 /*
523 * If watchdog was stopped before suspend be sure it gets disabled
524 * again, for the case BIOS has enabled it during resume
525 */
526 if (wdt_data->pm_status_store & KEMPLD_WDT_CFG_ENABLE)
527 return kempld_wdt_start(wdd);
528 else
529 return kempld_wdt_stop(wdd);
530 }
531
532 static struct platform_driver kempld_wdt_driver = {
533 .driver = {
534 .name = "kempld-wdt",
535 },
536 .probe = kempld_wdt_probe,
537 .suspend = pm_ptr(kempld_wdt_suspend),
538 .resume = pm_ptr(kempld_wdt_resume),
539 };
540
541 module_platform_driver(kempld_wdt_driver);
542
543 MODULE_DESCRIPTION("KEM PLD Watchdog Driver");
544 MODULE_AUTHOR("Michael Brunner <michael.brunner@kontron.com>");
545 MODULE_LICENSE("GPL");
546