summaryrefslogtreecommitdiffstats
path: root/drivers/watchdog/sp805_wdt.c
blob: c1b03f4235b99807d479672abdc6da0243107837 (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
/*
 * drivers/char/watchdog/sp805-wdt.c
 *
 * Watchdog driver for ARM SP805 watchdog module
 *
 * Copyright (C) 2010 ST Microelectronics
 * Viresh Kumar <viresh.linux@gmail.com>
 *
 * This file is licensed under the terms of the GNU General Public
 * License version 2 or later. This program is licensed "as is" without any
 * warranty of any kind, whether express or implied.
 */

#include <linux/device.h>
#include <linux/resource.h>
#include <linux/amba/bus.h>
#include <linux/bitops.h>
#include <linux/clk.h>
#include <linux/io.h>
#include <linux/ioport.h>
#include <linux/kernel.h>
#include <linux/math64.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/pm.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/types.h>
#include <linux/watchdog.h>

/* default timeout in seconds */
#define DEFAULT_TIMEOUT		60

#define MODULE_NAME		"sp805-wdt"

/* watchdog register offsets and masks */
#define WDTLOAD			0x000
	#define LOAD_MIN	0x00000001
	#define LOAD_MAX	0xFFFFFFFF
#define WDTVALUE		0x004
#define WDTCONTROL		0x008
	/* control register masks */
	#define	INT_ENABLE	(1 << 0)
	#define	RESET_ENABLE	(1 << 1)
#define WDTINTCLR		0x00C
#define WDTRIS			0x010
#define WDTMIS			0x014
	#define INT_MASK	(1 << 0)
#define WDTLOCK			0xC00
	#define	UNLOCK		0x1ACCE551
	#define	LOCK		0x00000001

/**
 * struct sp805_wdt: sp805 wdt device structure
 * @wdd: instance of struct watchdog_device
 * @lock: spin lock protecting dev structure and io access
 * @base: base address of wdt
 * @clk: clock structure of wdt
 * @adev: amba device structure of wdt
 * @status: current status of wdt
 * @load_val: load value to be set for current timeout
 */
struct sp805_wdt {
	struct watchdog_device		wdd;
	spinlock_t			lock;
	void __iomem			*base;
	struct clk			*clk;
	struct amba_device		*adev;
	unsigned int			load_val;
};

static bool nowayout = WATCHDOG_NOWAYOUT;
module_param(nowayout, bool, 0);
MODULE_PARM_DESC(nowayout,
		"Set to 1 to keep watchdog running after device release");

/* This routine finds load value that will reset system in required timout */
static int wdt_setload(struct watchdog_device *wdd, unsigned int timeout)
{
	struct sp805_wdt *wdt = watchdog_get_drvdata(wdd);
	u64 load, rate;

	rate = clk_get_rate(wdt->clk);

	/*
	 * sp805 runs counter with given value twice, after the end of first
	 * counter it gives an interrupt and then starts counter again. If
	 * interrupt already occurred then it resets the system. This is why
	 * load is half of what should be required.
	 */
	load = div_u64(rate, 2) * timeout - 1;

	load = (load > LOAD_MAX) ? LOAD_MAX : load;
	load = (load < LOAD_MIN) ? LOAD_MIN : load;

	spin_lock(&wdt->lock);
	wdt->load_val = load;
	/* roundup timeout to closest positive integer value */
	wdd->timeout = div_u64((load + 1) * 2 + (rate / 2), rate);
	spin_unlock(&wdt->lock);

	return 0;
}

/* returns number of seconds left for reset to occur */
static unsigned int wdt_timeleft(struct watchdog_device *wdd)
{
	struct sp805_wdt *wdt = watchdog_get_drvdata(wdd);
	u64 load, rate;

	rate = clk_get_rate(wdt->clk);

	spin_lock(&wdt->lock);
	load = readl_relaxed(wdt->base + WDTVALUE);

	/*If the interrupt is inactive then time left is WDTValue + WDTLoad. */
	if (!(readl_relaxed(wdt->base + WDTRIS) & INT_MASK))
		load += wdt->load_val + 1;
	spin_unlock(&wdt->lock);

	return div_u64(load, rate);
}

static int wdt_config(struct watchdog_device *wdd, bool ping)
{
	struct sp805_wdt *wdt = watchdog_get_drvdata(wdd);
	int ret;

	if (!ping) {

		ret = clk_prepare_enable(wdt->clk);
		if (ret) {
			dev_err(&wdt->adev->dev, "clock enable fail");
			return ret;
		}
	}

	spin_lock(&wdt->lock);

	writel_relaxed(UNLOCK, wdt->base + WDTLOCK);
	writel_relaxed(wdt->load_val, wdt->base + WDTLOAD);

	if (!ping) {
		writel_relaxed(INT_MASK, wdt->base + WDTINTCLR);
		writel_relaxed(INT_ENABLE | RESET_ENABLE, wdt->base +
				WDTCONTROL);
	}

	writel_relaxed(LOCK, wdt->base + WDTLOCK);

	/* Flush posted writes. */
	readl_relaxed(wdt->base + WDTLOCK);
	spin_unlock(&wdt->lock);

	return 0;
}

static int wdt_ping(struct watchdog_device *wdd)
{
	return wdt_config(wdd, true);
}

/* enables watchdog timers reset */
static int wdt_enable(struct watchdog_device *wdd)
{
	return wdt_config(wdd, false);
}

/* disables watchdog timers reset */
static int wdt_disable(struct watchdog_device *wdd)
{
	struct sp805_wdt *wdt = watchdog_get_drvdata(wdd);

	spin_lock(&wdt->lock);

	writel_relaxed(UNLOCK, wdt->base + WDTLOCK);
	writel_relaxed(0, wdt->base + WDTCONTROL);
	writel_relaxed(LOCK, wdt->base + WDTLOCK);

	/* Flush posted writes. */
	readl_relaxed(wdt->base + WDTLOCK);
	spin_unlock(&wdt->lock);

	clk_disable_unprepare(wdt->clk);

	return 0;
}

static const struct watchdog_info wdt_info = {
	.options = WDIOF_MAGICCLOSE | WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
	.identity = MODULE_NAME,
};

static const struct watchdog_ops wdt_ops = {
	.owner		= THIS_MODULE,
	.start		= wdt_enable,
	.stop		= wdt_disable,
	.ping		= wdt_ping,
	.set_timeout	= wdt_setload,
	.get_timeleft	= wdt_timeleft,
};

static int
sp805_wdt_probe(struct amba_device *adev, const struct amba_id *id)
{
	struct sp805_wdt *wdt;
	int ret = 0;

	wdt = devm_kzalloc(&adev->dev, sizeof(*wdt), GFP_KERNEL);
	if (!wdt) {
		ret = -ENOMEM;
		goto err;
	}

	wdt->base = devm_ioremap_resource(&adev->dev, &adev->res);
	if (IS_ERR(wdt->base))
		return PTR_ERR(wdt->base);

	wdt->clk = devm_clk_get(&adev->dev, NULL);
	if (IS_ERR(wdt->clk)) {
		dev_warn(&adev->dev, "Clock not found\n");
		ret = PTR_ERR(wdt->clk);
		goto err;
	}

	wdt->adev = adev;
	wdt->wdd.info = &wdt_info;
	wdt->wdd.ops = &wdt_ops;

	spin_lock_init(&wdt->lock);
	watchdog_set_nowayout(&wdt->wdd, nowayout);
	watchdog_set_drvdata(&wdt->wdd, wdt);
	wdt_setload(&wdt->wdd, DEFAULT_TIMEOUT);

	ret = watchdog_register_device(&wdt->wdd);
	if (ret) {
		dev_err(&adev->dev, "watchdog_register_device() failed: %d\n",
				ret);
		goto err;
	}
	amba_set_drvdata(adev, wdt);

	dev_info(&adev->dev, "registration successful\n");
	return 0;

err:
	dev_err(&adev->dev, "Probe Failed!!!\n");
	return ret;
}

static int sp805_wdt_remove(struct amba_device *adev)
{
	struct sp805_wdt *wdt = amba_get_drvdata(adev);

	watchdog_unregister_device(&wdt->wdd);
	watchdog_set_drvdata(&wdt->wdd, NULL);

	return 0;
}

static int __maybe_unused sp805_wdt_suspend(struct device *dev)
{
	struct sp805_wdt *wdt = dev_get_drvdata(dev);

	if (watchdog_active(&wdt->wdd))
		return wdt_disable(&wdt->wdd);

	return 0;
}

static int __maybe_unused sp805_wdt_resume(struct device *dev)
{
	struct sp805_wdt *wdt = dev_get_drvdata(dev);

	if (watchdog_active(&wdt->wdd))
		return wdt_enable(&wdt->wdd);

	return 0;
}

static SIMPLE_DEV_PM_OPS(sp805_wdt_dev_pm_ops, sp805_wdt_suspend,
		sp805_wdt_resume);

static struct amba_id sp805_wdt_ids[] = {
	{
		.id	= 0x00141805,
		.mask	= 0x00ffffff,
	},
	{ 0, 0 },
};

MODULE_DEVICE_TABLE(amba, sp805_wdt_ids);

static struct amba_driver sp805_wdt_driver = {
	.drv = {
		.name	= MODULE_NAME,
		.pm	= &sp805_wdt_dev_pm_ops,
	},
	.id_table	= sp805_wdt_ids,
	.probe		= sp805_wdt_probe,
	.remove = sp805_wdt_remove,
};

module_amba_driver(sp805_wdt_driver);

MODULE_AUTHOR("Viresh Kumar <viresh.linux@gmail.com>");
MODULE_DESCRIPTION("ARM SP805 Watchdog Driver");
MODULE_LICENSE("GPL");