summaryrefslogtreecommitdiffstats
path: root/drivers/watchdog/bcm_kona_wdt.c
blob: e0c98423f2c9d0c2203a14933a0061f3026b224e (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
/*
 * Copyright (C) 2013 Broadcom Corporation
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation version 2.
 *
 * This program is distributed "as is" WITHOUT ANY WARRANTY of any
 * kind, whether express or implied; without even the implied warranty
 * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 */

#include <linux/debugfs.h>
#include <linux/delay.h>
#include <linux/err.h>
#include <linux/io.h>
#include <linux/module.h>
#include <linux/of_address.h>
#include <linux/platform_device.h>
#include <linux/watchdog.h>

#define SECWDOG_CTRL_REG		0x00000000
#define SECWDOG_COUNT_REG		0x00000004

#define SECWDOG_RESERVED_MASK		0x1dffffff
#define SECWDOG_WD_LOAD_FLAG		0x10000000
#define SECWDOG_EN_MASK			0x08000000
#define SECWDOG_SRSTEN_MASK		0x04000000
#define SECWDOG_RES_MASK		0x00f00000
#define SECWDOG_COUNT_MASK		0x000fffff

#define SECWDOG_MAX_COUNT		SECWDOG_COUNT_MASK
#define SECWDOG_CLKS_SHIFT		20
#define SECWDOG_MAX_RES			15
#define SECWDOG_DEFAULT_RESOLUTION	4
#define SECWDOG_MAX_TRY			1000

#define SECS_TO_TICKS(x, w)		((x) << (w)->resolution)
#define TICKS_TO_SECS(x, w)		((x) >> (w)->resolution)

#define BCM_KONA_WDT_NAME		"bcm_kona_wdt"

struct bcm_kona_wdt {
	void __iomem *base;
	/*
	 * One watchdog tick is 1/(2^resolution) seconds. Resolution can take
	 * the values 0-15, meaning one tick can be 1s to 30.52us. Our default
	 * resolution of 4 means one tick is 62.5ms.
	 *
	 * The watchdog counter is 20 bits. Depending on resolution, the maximum
	 * counter value of 0xfffff expires after about 12 days (resolution 0)
	 * down to only 32s (resolution 15). The default resolution of 4 gives
	 * us a maximum of about 18 hours and 12 minutes before the watchdog
	 * times out.
	 */
	int resolution;
	spinlock_t lock;
#ifdef CONFIG_BCM_KONA_WDT_DEBUG
	unsigned long busy_count;
	struct dentry *debugfs;
#endif
};

static int secure_register_read(struct bcm_kona_wdt *wdt, uint32_t offset)
{
	uint32_t val;
	unsigned count = 0;

	/*
	 * If the WD_LOAD_FLAG is set, the watchdog counter field is being
	 * updated in hardware. Once the WD timer is updated in hardware, it
	 * gets cleared.
	 */
	do {
		if (unlikely(count > 1))
			udelay(5);
		val = readl_relaxed(wdt->base + offset);
		count++;
	} while ((val & SECWDOG_WD_LOAD_FLAG) && count < SECWDOG_MAX_TRY);

#ifdef CONFIG_BCM_KONA_WDT_DEBUG
	/* Remember the maximum number iterations due to WD_LOAD_FLAG */
	if (count > wdt->busy_count)
		wdt->busy_count = count;
#endif

	/* This is the only place we return a negative value. */
	if (val & SECWDOG_WD_LOAD_FLAG)
		return -ETIMEDOUT;

	/* We always mask out reserved bits. */
	val &= SECWDOG_RESERVED_MASK;

	return val;
}

#ifdef CONFIG_BCM_KONA_WDT_DEBUG

static int bcm_kona_wdt_dbg_show(struct seq_file *s, void *data)
{
	int ctl_val, cur_val;
	unsigned long flags;
	struct bcm_kona_wdt *wdt = s->private;

	if (!wdt) {
		seq_puts(s, "No device pointer\n");
		return 0;
	}

	spin_lock_irqsave(&wdt->lock, flags);
	ctl_val = secure_register_read(wdt, SECWDOG_CTRL_REG);
	cur_val = secure_register_read(wdt, SECWDOG_COUNT_REG);
	spin_unlock_irqrestore(&wdt->lock, flags);

	if (ctl_val < 0 || cur_val < 0) {
		seq_puts(s, "Error accessing hardware\n");
	} else {
		int ctl, cur, ctl_sec, cur_sec, res;

		ctl = ctl_val & SECWDOG_COUNT_MASK;
		res = (ctl_val & SECWDOG_RES_MASK) >> SECWDOG_CLKS_SHIFT;
		cur = cur_val & SECWDOG_COUNT_MASK;
		ctl_sec = TICKS_TO_SECS(ctl, wdt);
		cur_sec = TICKS_TO_SECS(cur, wdt);
		seq_printf(s,
			   "Resolution: %d / %d\n"
			   "Control: %d s / %d (%#x) ticks\n"
			   "Current: %d s / %d (%#x) ticks\n"
			   "Busy count: %lu\n",
			   res, wdt->resolution,
			   ctl_sec, ctl, ctl,
			   cur_sec, cur, cur,
			   wdt->busy_count);
	}

	return 0;
}

static int bcm_kona_dbg_open(struct inode *inode, struct file *file)
{
	return single_open(file, bcm_kona_wdt_dbg_show, inode->i_private);
}

static const struct file_operations bcm_kona_dbg_operations = {
	.open		= bcm_kona_dbg_open,
	.read		= seq_read,
	.llseek		= seq_lseek,
	.release	= single_release,
};

static void bcm_kona_wdt_debug_init(struct platform_device *pdev)
{
	struct dentry *dir;
	struct bcm_kona_wdt *wdt = platform_get_drvdata(pdev);

	if (!wdt)
		return;

	wdt->debugfs = NULL;

	dir = debugfs_create_dir(BCM_KONA_WDT_NAME, NULL);
	if (IS_ERR_OR_NULL(dir))
		return;

	if (debugfs_create_file("info", S_IFREG | S_IRUGO, dir, wdt,
				&bcm_kona_dbg_operations))
		wdt->debugfs = dir;
	else
		debugfs_remove_recursive(dir);
}

static void bcm_kona_wdt_debug_exit(struct platform_device *pdev)
{
	struct bcm_kona_wdt *wdt = platform_get_drvdata(pdev);

	if (wdt && wdt->debugfs) {
		debugfs_remove_recursive(wdt->debugfs);
		wdt->debugfs = NULL;
	}
}

#else

static void bcm_kona_wdt_debug_init(struct platform_device *pdev) {}
static void bcm_kona_wdt_debug_exit(struct platform_device *pdev) {}

#endif /* CONFIG_BCM_KONA_WDT_DEBUG */

static int bcm_kona_wdt_ctrl_reg_modify(struct bcm_kona_wdt *wdt,
					unsigned mask, unsigned newval)
{
	int val;
	unsigned long flags;
	int ret = 0;

	spin_lock_irqsave(&wdt->lock, flags);

	val = secure_register_read(wdt, SECWDOG_CTRL_REG);
	if (val < 0) {
		ret = val;
	} else {
		val &= ~mask;
		val |= newval;
		writel_relaxed(val, wdt->base + SECWDOG_CTRL_REG);
	}

	spin_unlock_irqrestore(&wdt->lock, flags);

	return ret;
}

static int bcm_kona_wdt_set_resolution_reg(struct bcm_kona_wdt *wdt)
{
	if (wdt->resolution > SECWDOG_MAX_RES)
		return -EINVAL;

	return bcm_kona_wdt_ctrl_reg_modify(wdt, SECWDOG_RES_MASK,
					wdt->resolution << SECWDOG_CLKS_SHIFT);
}

static int bcm_kona_wdt_set_timeout_reg(struct watchdog_device *wdog,
					unsigned watchdog_flags)
{
	struct bcm_kona_wdt *wdt = watchdog_get_drvdata(wdog);

	return bcm_kona_wdt_ctrl_reg_modify(wdt, SECWDOG_COUNT_MASK,
					SECS_TO_TICKS(wdog->timeout, wdt) |
					watchdog_flags);
}

static int bcm_kona_wdt_set_timeout(struct watchdog_device *wdog,
	unsigned int t)
{
	wdog->timeout = t;
	return 0;
}

static unsigned int bcm_kona_wdt_get_timeleft(struct watchdog_device *wdog)
{
	struct bcm_kona_wdt *wdt = watchdog_get_drvdata(wdog);
	int val;
	unsigned long flags;

	spin_lock_irqsave(&wdt->lock, flags);
	val = secure_register_read(wdt, SECWDOG_COUNT_REG);
	spin_unlock_irqrestore(&wdt->lock, flags);

	if (val < 0)
		return val;

	return TICKS_TO_SECS(val & SECWDOG_COUNT_MASK, wdt);
}

static int bcm_kona_wdt_start(struct watchdog_device *wdog)
{
	return bcm_kona_wdt_set_timeout_reg(wdog,
					SECWDOG_EN_MASK | SECWDOG_SRSTEN_MASK);
}

static int bcm_kona_wdt_stop(struct watchdog_device *wdog)
{
	struct bcm_kona_wdt *wdt = watchdog_get_drvdata(wdog);

	return bcm_kona_wdt_ctrl_reg_modify(wdt, SECWDOG_EN_MASK |
					    SECWDOG_SRSTEN_MASK, 0);
}

static struct watchdog_ops bcm_kona_wdt_ops = {
	.owner =	THIS_MODULE,
	.start =	bcm_kona_wdt_start,
	.stop =		bcm_kona_wdt_stop,
	.set_timeout =	bcm_kona_wdt_set_timeout,
	.get_timeleft =	bcm_kona_wdt_get_timeleft,
};

static struct watchdog_info bcm_kona_wdt_info = {
	.options =	WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE |
			WDIOF_KEEPALIVEPING,
	.identity =	"Broadcom Kona Watchdog Timer",
};

static struct watchdog_device bcm_kona_wdt_wdd = {
	.info =		&bcm_kona_wdt_info,
	.ops =		&bcm_kona_wdt_ops,
	.min_timeout =	1,
	.max_timeout =	SECWDOG_MAX_COUNT >> SECWDOG_DEFAULT_RESOLUTION,
	.timeout =	SECWDOG_MAX_COUNT >> SECWDOG_DEFAULT_RESOLUTION,
};

static void bcm_kona_wdt_shutdown(struct platform_device *pdev)
{
	bcm_kona_wdt_stop(&bcm_kona_wdt_wdd);
}

static int bcm_kona_wdt_probe(struct platform_device *pdev)
{
	struct device *dev = &pdev->dev;
	struct bcm_kona_wdt *wdt;
	struct resource *res;
	int ret;

	wdt = devm_kzalloc(dev, sizeof(*wdt), GFP_KERNEL);
	if (!wdt)
		return -ENOMEM;

	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	wdt->base = devm_ioremap_resource(dev, res);
	if (IS_ERR(wdt->base))
		return -ENODEV;

	wdt->resolution = SECWDOG_DEFAULT_RESOLUTION;
	ret = bcm_kona_wdt_set_resolution_reg(wdt);
	if (ret) {
		dev_err(dev, "Failed to set resolution (error: %d)", ret);
		return ret;
	}

	spin_lock_init(&wdt->lock);
	platform_set_drvdata(pdev, wdt);
	watchdog_set_drvdata(&bcm_kona_wdt_wdd, wdt);
	bcm_kona_wdt_wdd.parent = &pdev->dev;

	ret = bcm_kona_wdt_set_timeout_reg(&bcm_kona_wdt_wdd, 0);
	if (ret) {
		dev_err(dev, "Failed set watchdog timeout");
		return ret;
	}

	ret = watchdog_register_device(&bcm_kona_wdt_wdd);
	if (ret) {
		dev_err(dev, "Failed to register watchdog device");
		return ret;
	}

	bcm_kona_wdt_debug_init(pdev);
	dev_dbg(dev, "Broadcom Kona Watchdog Timer");

	return 0;
}

static int bcm_kona_wdt_remove(struct platform_device *pdev)
{
	bcm_kona_wdt_debug_exit(pdev);
	bcm_kona_wdt_shutdown(pdev);
	watchdog_unregister_device(&bcm_kona_wdt_wdd);
	dev_dbg(&pdev->dev, "Watchdog driver disabled");

	return 0;
}

static const struct of_device_id bcm_kona_wdt_of_match[] = {
	{ .compatible = "brcm,kona-wdt", },
	{},
};
MODULE_DEVICE_TABLE(of, bcm_kona_wdt_of_match);

static struct platform_driver bcm_kona_wdt_driver = {
	.driver = {
			.name = BCM_KONA_WDT_NAME,
			.of_match_table = bcm_kona_wdt_of_match,
		  },
	.probe = bcm_kona_wdt_probe,
	.remove = bcm_kona_wdt_remove,
	.shutdown = bcm_kona_wdt_shutdown,
};

module_platform_driver(bcm_kona_wdt_driver);

MODULE_ALIAS("platform:" BCM_KONA_WDT_NAME);
MODULE_AUTHOR("Markus Mayer <mmayer@broadcom.com>");
MODULE_DESCRIPTION("Broadcom Kona Watchdog Driver");
MODULE_LICENSE("GPL v2");