1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * ACPI Hardware Watchdog (WDAT) driver.
4 *
5 * Copyright (C) 2016, Intel Corporation
6 * Author: Mika Westerberg <mika.westerberg@linux.intel.com>
7 */
8
9#include <linux/acpi.h>
10#include <linux/ioport.h>
11#include <linux/module.h>
12#include <linux/platform_device.h>
13#include <linux/pm.h>
14#include <linux/watchdog.h>
15
16#define MAX_WDAT_ACTIONS ACPI_WDAT_ACTION_RESERVED
17
18/**
19 * struct wdat_instruction - Single ACPI WDAT instruction
20 * @entry: Copy of the ACPI table instruction
21 * @reg: Register the instruction is accessing
22 * @node: Next instruction in action sequence
23 */
24struct wdat_instruction {
25	struct acpi_wdat_entry entry;
26	void __iomem *reg;
27	struct list_head node;
28};
29
30/**
31 * struct wdat_wdt - ACPI WDAT watchdog device
32 * @pdev: Parent platform device
33 * @wdd: Watchdog core device
34 * @period: How long is one watchdog period in ms
35 * @stopped_in_sleep: Is this watchdog stopped by the firmware in S1-S5
36 * @stopped: Was the watchdog stopped by the driver in suspend
37 * @instructions: An array of instruction lists indexed by an action number from
38 *                the WDAT table. There can be %NULL entries for not implemented
39 *                actions.
40 */
41struct wdat_wdt {
42	struct platform_device *pdev;
43	struct watchdog_device wdd;
44	unsigned int period;
45	bool stopped_in_sleep;
46	bool stopped;
47	struct list_head *instructions[MAX_WDAT_ACTIONS];
48};
49
50#define to_wdat_wdt(wdd) container_of(wdd, struct wdat_wdt, wdd)
51
52static bool nowayout = WATCHDOG_NOWAYOUT;
53module_param(nowayout, bool, 0);
54MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
55		 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
56
57#define WDAT_DEFAULT_TIMEOUT	30
58
59static int timeout = WDAT_DEFAULT_TIMEOUT;
60module_param(timeout, int, 0);
61MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds (default="
62		 __MODULE_STRING(WDAT_DEFAULT_TIMEOUT) ")");
63
64static int wdat_wdt_read(struct wdat_wdt *wdat,
65	 const struct wdat_instruction *instr, u32 *value)
66{
67	const struct acpi_generic_address *gas = &instr->entry.register_region;
68
69	switch (gas->access_width) {
70	case 1:
71		*value = ioread8(instr->reg);
72		break;
73	case 2:
74		*value = ioread16(instr->reg);
75		break;
76	case 3:
77		*value = ioread32(instr->reg);
78		break;
79	default:
80		return -EINVAL;
81	}
82
83	dev_dbg(&wdat->pdev->dev, "Read %#x from 0x%08llx\n", *value,
84		gas->address);
85
86	return 0;
87}
88
89static int wdat_wdt_write(struct wdat_wdt *wdat,
90	const struct wdat_instruction *instr, u32 value)
91{
92	const struct acpi_generic_address *gas = &instr->entry.register_region;
93
94	switch (gas->access_width) {
95	case 1:
96		iowrite8((u8)value, instr->reg);
97		break;
98	case 2:
99		iowrite16((u16)value, instr->reg);
100		break;
101	case 3:
102		iowrite32(value, instr->reg);
103		break;
104	default:
105		return -EINVAL;
106	}
107
108	dev_dbg(&wdat->pdev->dev, "Wrote %#x to 0x%08llx\n", value,
109		gas->address);
110
111	return 0;
112}
113
114static int wdat_wdt_run_action(struct wdat_wdt *wdat, unsigned int action,
115			       u32 param, u32 *retval)
116{
117	struct wdat_instruction *instr;
118
119	if (action >= ARRAY_SIZE(wdat->instructions))
120		return -EINVAL;
121
122	if (!wdat->instructions[action])
123		return -EOPNOTSUPP;
124
125	dev_dbg(&wdat->pdev->dev, "Running action %#x\n", action);
126
127	/* Run each instruction sequentially */
128	list_for_each_entry(instr, wdat->instructions[action], node) {
129		const struct acpi_wdat_entry *entry = &instr->entry;
130		const struct acpi_generic_address *gas;
131		u32 flags, value, mask, x, y;
132		bool preserve;
133		int ret;
134
135		gas = &entry->register_region;
136
137		preserve = entry->instruction & ACPI_WDAT_PRESERVE_REGISTER;
138		flags = entry->instruction & ~ACPI_WDAT_PRESERVE_REGISTER;
139		value = entry->value;
140		mask = entry->mask;
141
142		switch (flags) {
143		case ACPI_WDAT_READ_VALUE:
144			ret = wdat_wdt_read(wdat, instr, &x);
145			if (ret)
146				return ret;
147			x >>= gas->bit_offset;
148			x &= mask;
149			if (retval)
150				*retval = x == value;
151			break;
152
153		case ACPI_WDAT_READ_COUNTDOWN:
154			ret = wdat_wdt_read(wdat, instr, &x);
155			if (ret)
156				return ret;
157			x >>= gas->bit_offset;
158			x &= mask;
159			if (retval)
160				*retval = x;
161			break;
162
163		case ACPI_WDAT_WRITE_VALUE:
164			x = value & mask;
165			x <<= gas->bit_offset;
166			if (preserve) {
167				ret = wdat_wdt_read(wdat, instr, &y);
168				if (ret)
169					return ret;
170				y = y & ~(mask << gas->bit_offset);
171				x |= y;
172			}
173			ret = wdat_wdt_write(wdat, instr, x);
174			if (ret)
175				return ret;
176			break;
177
178		case ACPI_WDAT_WRITE_COUNTDOWN:
179			x = param;
180			x &= mask;
181			x <<= gas->bit_offset;
182			if (preserve) {
183				ret = wdat_wdt_read(wdat, instr, &y);
184				if (ret)
185					return ret;
186				y = y & ~(mask << gas->bit_offset);
187				x |= y;
188			}
189			ret = wdat_wdt_write(wdat, instr, x);
190			if (ret)
191				return ret;
192			break;
193
194		default:
195			dev_err(&wdat->pdev->dev, "Unknown instruction: %u\n",
196				flags);
197			return -EINVAL;
198		}
199	}
200
201	return 0;
202}
203
204static int wdat_wdt_enable_reboot(struct wdat_wdt *wdat)
205{
206	int ret;
207
208	/*
209	 * WDAT specification says that the watchdog is required to reboot
210	 * the system when it fires. However, it also states that it is
211	 * recommended to make it configurable through hardware register. We
212	 * enable reboot now if it is configurable, just in case.
213	 */
214	ret = wdat_wdt_run_action(wdat, ACPI_WDAT_SET_REBOOT, 0, NULL);
215	if (ret && ret != -EOPNOTSUPP) {
216		dev_err(&wdat->pdev->dev,
217			"Failed to enable reboot when watchdog triggers\n");
218		return ret;
219	}
220
221	return 0;
222}
223
224static void wdat_wdt_boot_status(struct wdat_wdt *wdat)
225{
226	u32 boot_status = 0;
227	int ret;
228
229	ret = wdat_wdt_run_action(wdat, ACPI_WDAT_GET_STATUS, 0, &boot_status);
230	if (ret && ret != -EOPNOTSUPP) {
231		dev_err(&wdat->pdev->dev, "Failed to read boot status\n");
232		return;
233	}
234
235	if (boot_status)
236		wdat->wdd.bootstatus = WDIOF_CARDRESET;
237
238	/* Clear the boot status in case BIOS did not do it */
239	ret = wdat_wdt_run_action(wdat, ACPI_WDAT_SET_STATUS, 0, NULL);
240	if (ret && ret != -EOPNOTSUPP)
241		dev_err(&wdat->pdev->dev, "Failed to clear boot status\n");
242}
243
244static void wdat_wdt_set_running(struct wdat_wdt *wdat)
245{
246	u32 running = 0;
247	int ret;
248
249	ret = wdat_wdt_run_action(wdat, ACPI_WDAT_GET_RUNNING_STATE, 0,
250				  &running);
251	if (ret && ret != -EOPNOTSUPP)
252		dev_err(&wdat->pdev->dev, "Failed to read running state\n");
253
254	if (running)
255		set_bit(WDOG_HW_RUNNING, &wdat->wdd.status);
256}
257
258static int wdat_wdt_start(struct watchdog_device *wdd)
259{
260	return wdat_wdt_run_action(to_wdat_wdt(wdd),
261				   ACPI_WDAT_SET_RUNNING_STATE, 0, NULL);
262}
263
264static int wdat_wdt_stop(struct watchdog_device *wdd)
265{
266	return wdat_wdt_run_action(to_wdat_wdt(wdd),
267				   ACPI_WDAT_SET_STOPPED_STATE, 0, NULL);
268}
269
270static int wdat_wdt_ping(struct watchdog_device *wdd)
271{
272	return wdat_wdt_run_action(to_wdat_wdt(wdd), ACPI_WDAT_RESET, wdd->timeout, NULL);
273}
274
275static int wdat_wdt_set_timeout(struct watchdog_device *wdd,
276				unsigned int timeout)
277{
278	struct wdat_wdt *wdat = to_wdat_wdt(wdd);
279	unsigned int periods;
280	int ret;
281
282	periods = timeout * 1000 / wdat->period;
283	ret = wdat_wdt_run_action(wdat, ACPI_WDAT_SET_COUNTDOWN, periods, NULL);
284	if (!ret)
285		wdd->timeout = timeout;
286	return ret;
287}
288
289static unsigned int wdat_wdt_get_timeleft(struct watchdog_device *wdd)
290{
291	struct wdat_wdt *wdat = to_wdat_wdt(wdd);
292	u32 periods = 0;
293
294	wdat_wdt_run_action(wdat, ACPI_WDAT_GET_CURRENT_COUNTDOWN, 0, &periods);
295	return periods * wdat->period / 1000;
296}
297
298static const struct watchdog_info wdat_wdt_info = {
299	.options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
300	.firmware_version = 0,
301	.identity = "wdat_wdt",
302};
303
304static struct watchdog_ops wdat_wdt_ops = {
305	.owner = THIS_MODULE,
306	.start = wdat_wdt_start,
307	.stop = wdat_wdt_stop,
308	.ping = wdat_wdt_ping,
309	.set_timeout = wdat_wdt_set_timeout,
310};
311
312static int wdat_wdt_probe(struct platform_device *pdev)
313{
314	struct device *dev = &pdev->dev;
315	const struct acpi_wdat_entry *entries;
316	const struct acpi_table_wdat *tbl;
317	struct wdat_wdt *wdat;
318	struct resource *res;
319	void __iomem **regs;
320	acpi_status status;
321	int i, ret;
322
323	status = acpi_get_table(ACPI_SIG_WDAT, 0,
324				(struct acpi_table_header **)&tbl);
325	if (ACPI_FAILURE(status))
326		return -ENODEV;
327
328	wdat = devm_kzalloc(dev, sizeof(*wdat), GFP_KERNEL);
329	if (!wdat)
330		return -ENOMEM;
331
332	regs = devm_kcalloc(dev, pdev->num_resources, sizeof(*regs),
333			    GFP_KERNEL);
334	if (!regs)
335		return -ENOMEM;
336
337	/* WDAT specification wants to have >= 1ms period */
338	if (tbl->timer_period < 1)
339		return -EINVAL;
340	if (tbl->min_count > tbl->max_count)
341		return -EINVAL;
342
343	wdat->period = tbl->timer_period;
344	wdat->wdd.min_timeout = DIV_ROUND_UP(wdat->period * tbl->min_count, 1000);
345	wdat->wdd.max_timeout = wdat->period * tbl->max_count / 1000;
346	wdat->stopped_in_sleep = tbl->flags & ACPI_WDAT_STOPPED;
347	wdat->wdd.info = &wdat_wdt_info;
348	wdat->wdd.ops = &wdat_wdt_ops;
349	wdat->pdev = pdev;
350
351	/* Request and map all resources */
352	for (i = 0; i < pdev->num_resources; i++) {
353		void __iomem *reg;
354
355		res = &pdev->resource[i];
356		if (resource_type(res) == IORESOURCE_MEM) {
357			reg = devm_ioremap_resource(dev, res);
358			if (IS_ERR(reg))
359				return PTR_ERR(reg);
360		} else if (resource_type(res) == IORESOURCE_IO) {
361			reg = devm_ioport_map(dev, res->start, 1);
362			if (!reg)
363				return -ENOMEM;
364		} else {
365			dev_err(dev, "Unsupported resource\n");
366			return -EINVAL;
367		}
368
369		regs[i] = reg;
370	}
371
372	entries = (struct acpi_wdat_entry *)(tbl + 1);
373	for (i = 0; i < tbl->entries; i++) {
374		const struct acpi_generic_address *gas;
375		struct wdat_instruction *instr;
376		struct list_head *instructions;
377		unsigned int action;
378		struct resource r;
379		int j;
380
381		action = entries[i].action;
382		if (action >= MAX_WDAT_ACTIONS) {
383			dev_dbg(dev, "Skipping unknown action: %u\n", action);
384			continue;
385		}
386
387		instr = devm_kzalloc(dev, sizeof(*instr), GFP_KERNEL);
388		if (!instr)
389			return -ENOMEM;
390
391		INIT_LIST_HEAD(&instr->node);
392		instr->entry = entries[i];
393
394		gas = &entries[i].register_region;
395
396		memset(&r, 0, sizeof(r));
397		r.start = gas->address;
398		r.end = r.start + ACPI_ACCESS_BYTE_WIDTH(gas->access_width) - 1;
399		if (gas->space_id == ACPI_ADR_SPACE_SYSTEM_MEMORY) {
400			r.flags = IORESOURCE_MEM;
401		} else if (gas->space_id == ACPI_ADR_SPACE_SYSTEM_IO) {
402			r.flags = IORESOURCE_IO;
403		} else {
404			dev_dbg(dev, "Unsupported address space: %d\n",
405				gas->space_id);
406			continue;
407		}
408
409		/* Find the matching resource */
410		for (j = 0; j < pdev->num_resources; j++) {
411			res = &pdev->resource[j];
412			if (resource_contains(res, &r)) {
413				instr->reg = regs[j] + r.start - res->start;
414				break;
415			}
416		}
417
418		if (!instr->reg) {
419			dev_err(dev, "I/O resource not found\n");
420			return -EINVAL;
421		}
422
423		instructions = wdat->instructions[action];
424		if (!instructions) {
425			instructions = devm_kzalloc(dev,
426						    sizeof(*instructions),
427						    GFP_KERNEL);
428			if (!instructions)
429				return -ENOMEM;
430
431			INIT_LIST_HEAD(instructions);
432			wdat->instructions[action] = instructions;
433		}
434
435		list_add_tail(&instr->node, instructions);
436	}
437
438	if (wdat->instructions[ACPI_WDAT_GET_CURRENT_COUNTDOWN])
439		wdat_wdt_ops.get_timeleft = wdat_wdt_get_timeleft;
440
441	wdat_wdt_boot_status(wdat);
442	wdat_wdt_set_running(wdat);
443
444	ret = wdat_wdt_enable_reboot(wdat);
445	if (ret)
446		return ret;
447
448	platform_set_drvdata(pdev, wdat);
449
450	/*
451	 * Set initial timeout so that userspace has time to configure the
452	 * watchdog properly after it has opened the device. In some cases
453	 * the BIOS default is too short and causes immediate reboot.
454	 */
455	if (watchdog_timeout_invalid(&wdat->wdd, timeout)) {
456		dev_warn(dev, "Invalid timeout %d given, using %d\n",
457			 timeout, WDAT_DEFAULT_TIMEOUT);
458		timeout = WDAT_DEFAULT_TIMEOUT;
459	}
460
461	ret = wdat_wdt_set_timeout(&wdat->wdd, timeout);
462	if (ret)
463		return ret;
464
465	watchdog_set_nowayout(&wdat->wdd, nowayout);
466	watchdog_stop_on_reboot(&wdat->wdd);
467	watchdog_stop_on_unregister(&wdat->wdd);
468	return devm_watchdog_register_device(dev, &wdat->wdd);
469}
470
471static int wdat_wdt_suspend_noirq(struct device *dev)
472{
473	struct wdat_wdt *wdat = dev_get_drvdata(dev);
474	int ret;
475
476	if (!watchdog_active(&wdat->wdd))
477		return 0;
478
479	/*
480	 * We need to stop the watchdog if firmware is not doing it or if we
481	 * are going suspend to idle (where firmware is not involved). If
482	 * firmware is stopping the watchdog we kick it here one more time
483	 * to give it some time.
484	 */
485	wdat->stopped = false;
486	if (acpi_target_system_state() == ACPI_STATE_S0 ||
487	    !wdat->stopped_in_sleep) {
488		ret = wdat_wdt_stop(&wdat->wdd);
489		if (!ret)
490			wdat->stopped = true;
491	} else {
492		ret = wdat_wdt_ping(&wdat->wdd);
493	}
494
495	return ret;
496}
497
498static int wdat_wdt_resume_noirq(struct device *dev)
499{
500	struct wdat_wdt *wdat = dev_get_drvdata(dev);
501	int ret;
502
503	if (!watchdog_active(&wdat->wdd))
504		return 0;
505
506	if (!wdat->stopped) {
507		/*
508		 * Looks like the boot firmware reinitializes the watchdog
509		 * before it hands off to the OS on resume from sleep so we
510		 * stop and reprogram the watchdog here.
511		 */
512		ret = wdat_wdt_stop(&wdat->wdd);
513		if (ret)
514			return ret;
515
516		ret = wdat_wdt_set_timeout(&wdat->wdd, wdat->wdd.timeout);
517		if (ret)
518			return ret;
519
520		ret = wdat_wdt_enable_reboot(wdat);
521		if (ret)
522			return ret;
523
524		ret = wdat_wdt_ping(&wdat->wdd);
525		if (ret)
526			return ret;
527	}
528
529	return wdat_wdt_start(&wdat->wdd);
530}
531
532static const struct dev_pm_ops wdat_wdt_pm_ops = {
533	NOIRQ_SYSTEM_SLEEP_PM_OPS(wdat_wdt_suspend_noirq, wdat_wdt_resume_noirq)
534};
535
536static struct platform_driver wdat_wdt_driver = {
537	.probe = wdat_wdt_probe,
538	.driver = {
539		.name = "wdat_wdt",
540		.pm = pm_sleep_ptr(&wdat_wdt_pm_ops),
541	},
542};
543
544module_platform_driver(wdat_wdt_driver);
545
546MODULE_AUTHOR("Mika Westerberg <mika.westerberg@linux.intel.com>");
547MODULE_DESCRIPTION("ACPI Hardware Watchdog (WDAT) driver");
548MODULE_LICENSE("GPL v2");
549MODULE_ALIAS("platform:wdat_wdt");
550