summaryrefslogtreecommitdiffstats
path: root/drivers/watchdog/gef_wdt.c
blob: 29a7cd4b90c839cdb8986dee2bc526a15a07f733 (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
/*
 * GE watchdog userspace interface
 *
 * Author:  Martyn Welch <martyn.welch@ge.com>
 *
 * Copyright 2008 GE Intelligent Platforms Embedded Systems, Inc.
 *
 * 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;  either version 2 of the  License, or (at your
 * option) any later version.
 *
 * Based on: mv64x60_wdt.c (MV64X60 watchdog userspace interface)
 *   Author: James Chapman <jchapman@katalix.com>
 */

/* TODO:
 * This driver does not provide support for the hardwares capability of sending
 * an interrupt at a programmable threshold.
 *
 * This driver currently can only support 1 watchdog - there are 2 in the
 * hardware that this driver supports. Thus one could be configured as a
 * process-based watchdog (via /dev/watchdog), the second (using the interrupt
 * capabilities) a kernel-based watchdog.
 */

#include <linux/kernel.h>
#include <linux/compiler.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/miscdevice.h>
#include <linux/watchdog.h>
#include <linux/fs.h>
#include <linux/of.h>
#include <linux/of_platform.h>
#include <linux/io.h>
#include <linux/uaccess.h>

#include <sysdev/fsl_soc.h>

/*
 * The watchdog configuration register contains a pair of 2-bit fields,
 *   1.  a reload field, bits 27-26, which triggers a reload of
 *       the countdown register, and
 *   2.  an enable field, bits 25-24, which toggles between
 *       enabling and disabling the watchdog timer.
 * Bit 31 is a read-only field which indicates whether the
 * watchdog timer is currently enabled.
 *
 * The low 24 bits contain the timer reload value.
 */
#define GEF_WDC_ENABLE_SHIFT	24
#define GEF_WDC_SERVICE_SHIFT	26
#define GEF_WDC_ENABLED_SHIFT	31

#define GEF_WDC_ENABLED_TRUE	1
#define GEF_WDC_ENABLED_FALSE	0

/* Flags bits */
#define GEF_WDOG_FLAG_OPENED	0

static unsigned long wdt_flags;
static int wdt_status;
static void __iomem *gef_wdt_regs;
static int gef_wdt_timeout;
static int gef_wdt_count;
static unsigned int bus_clk;
static char expect_close;
static DEFINE_SPINLOCK(gef_wdt_spinlock);

static int nowayout = WATCHDOG_NOWAYOUT;
module_param(nowayout, int, 0);
MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
	__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");


static int gef_wdt_toggle_wdc(int enabled_predicate, int field_shift)
{
	u32 data;
	u32 enabled;
	int ret = 0;

	spin_lock(&gef_wdt_spinlock);
	data = ioread32be(gef_wdt_regs);
	enabled = (data >> GEF_WDC_ENABLED_SHIFT) & 1;

	/* only toggle the requested field if enabled state matches predicate */
	if ((enabled ^ enabled_predicate) == 0) {
		/* We write a 1, then a 2 -- to the appropriate field */
		data = (1 << field_shift) | gef_wdt_count;
		iowrite32be(data, gef_wdt_regs);

		data = (2 << field_shift) | gef_wdt_count;
		iowrite32be(data, gef_wdt_regs);
		ret = 1;
	}
	spin_unlock(&gef_wdt_spinlock);

	return ret;
}

static void gef_wdt_service(void)
{
	gef_wdt_toggle_wdc(GEF_WDC_ENABLED_TRUE,
		GEF_WDC_SERVICE_SHIFT);
}

static void gef_wdt_handler_enable(void)
{
	if (gef_wdt_toggle_wdc(GEF_WDC_ENABLED_FALSE,
				   GEF_WDC_ENABLE_SHIFT)) {
		gef_wdt_service();
		printk(KERN_NOTICE "gef_wdt: watchdog activated\n");
	}
}

static void gef_wdt_handler_disable(void)
{
	if (gef_wdt_toggle_wdc(GEF_WDC_ENABLED_TRUE,
				   GEF_WDC_ENABLE_SHIFT))
		printk(KERN_NOTICE "gef_wdt: watchdog deactivated\n");
}

static void gef_wdt_set_timeout(unsigned int timeout)
{
	/* maximum bus cycle count is 0xFFFFFFFF */
	if (timeout > 0xFFFFFFFF / bus_clk)
		timeout = 0xFFFFFFFF / bus_clk;

	/* Register only holds upper 24 bits, bit shifted into lower 24 */
	gef_wdt_count = (timeout * bus_clk) >> 8;
	gef_wdt_timeout = timeout;
}


static ssize_t gef_wdt_write(struct file *file, const char __user *data,
				 size_t len, loff_t *ppos)
{
	if (len) {
		if (!nowayout) {
			size_t i;

			expect_close = 0;

			for (i = 0; i != len; i++) {
				char c;
				if (get_user(c, data + i))
					return -EFAULT;
				if (c == 'V')
					expect_close = 42;
			}
		}
		gef_wdt_service();
	}

	return len;
}

static long gef_wdt_ioctl(struct file *file, unsigned int cmd,
							unsigned long arg)
{
	int timeout;
	int options;
	void __user *argp = (void __user *)arg;
	static const struct watchdog_info info = {
		.options =	WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE |
				WDIOF_KEEPALIVEPING,
		.firmware_version = 0,
		.identity = "GE watchdog",
	};

	switch (cmd) {
	case WDIOC_GETSUPPORT:
		if (copy_to_user(argp, &info, sizeof(info)))
			return -EFAULT;
		break;

	case WDIOC_GETSTATUS:
	case WDIOC_GETBOOTSTATUS:
		if (put_user(wdt_status, (int __user *)argp))
			return -EFAULT;
		wdt_status &= ~WDIOF_KEEPALIVEPING;
		break;

	case WDIOC_SETOPTIONS:
		if (get_user(options, (int __user *)argp))
			return -EFAULT;

		if (options & WDIOS_DISABLECARD)
			gef_wdt_handler_disable();

		if (options & WDIOS_ENABLECARD)
			gef_wdt_handler_enable();
		break;

	case WDIOC_KEEPALIVE:
		gef_wdt_service();
		wdt_status |= WDIOF_KEEPALIVEPING;
		break;

	case WDIOC_SETTIMEOUT:
		if (get_user(timeout, (int __user *)argp))
			return -EFAULT;
		gef_wdt_set_timeout(timeout);
		/* Fall through */

	case WDIOC_GETTIMEOUT:
		if (put_user(gef_wdt_timeout, (int __user *)argp))
			return -EFAULT;
		break;

	default:
		return -ENOTTY;
	}

	return 0;
}

static int gef_wdt_open(struct inode *inode, struct file *file)
{
	if (test_and_set_bit(GEF_WDOG_FLAG_OPENED, &wdt_flags))
		return -EBUSY;

	if (nowayout)
		__module_get(THIS_MODULE);

	gef_wdt_handler_enable();

	return nonseekable_open(inode, file);
}

static int gef_wdt_release(struct inode *inode, struct file *file)
{
	if (expect_close == 42)
		gef_wdt_handler_disable();
	else {
		printk(KERN_CRIT
		       "gef_wdt: unexpected close, not stopping timer!\n");
		gef_wdt_service();
	}
	expect_close = 0;

	clear_bit(GEF_WDOG_FLAG_OPENED, &wdt_flags);

	return 0;
}

static const struct file_operations gef_wdt_fops = {
	.owner = THIS_MODULE,
	.llseek = no_llseek,
	.write = gef_wdt_write,
	.unlocked_ioctl = gef_wdt_ioctl,
	.open = gef_wdt_open,
	.release = gef_wdt_release,
};

static struct miscdevice gef_wdt_miscdev = {
	.minor = WATCHDOG_MINOR,
	.name = "watchdog",
	.fops = &gef_wdt_fops,
};


static int __devinit gef_wdt_probe(struct platform_device *dev)
{
	int timeout = 10;
	u32 freq;

	bus_clk = 133; /* in MHz */

	freq = fsl_get_sys_freq();
	if (freq != -1)
		bus_clk = freq;

	/* Map devices registers into memory */
	gef_wdt_regs = of_iomap(dev->dev.of_node, 0);
	if (gef_wdt_regs == NULL)
		return -ENOMEM;

	gef_wdt_set_timeout(timeout);

	gef_wdt_handler_disable();	/* in case timer was already running */

	return misc_register(&gef_wdt_miscdev);
}

static int __devexit gef_wdt_remove(struct platform_device *dev)
{
	misc_deregister(&gef_wdt_miscdev);

	gef_wdt_handler_disable();

	iounmap(gef_wdt_regs);

	return 0;
}

static const struct of_device_id gef_wdt_ids[] = {
	{
		.compatible = "gef,fpga-wdt",
	},
	{},
};

static struct platform_driver gef_wdt_driver = {
	.driver = {
		.name = "gef_wdt",
		.owner = THIS_MODULE,
		.of_match_table = gef_wdt_ids,
	},
	.probe		= gef_wdt_probe,
};

static int __init gef_wdt_init(void)
{
	printk(KERN_INFO "GE watchdog driver\n");
	return platform_driver_register(&gef_wdt_driver);
}

static void __exit gef_wdt_exit(void)
{
	platform_driver_unregister(&gef_wdt_driver);
}

module_init(gef_wdt_init);
module_exit(gef_wdt_exit);

MODULE_AUTHOR("Martyn Welch <martyn.welch@ge.com>");
MODULE_DESCRIPTION("GE watchdog driver");
MODULE_LICENSE("GPL");
MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
MODULE_ALIAS("platform: gef_wdt");
OpenPOWER on IntegriCloud