summaryrefslogtreecommitdiffstats
path: root/drivers/watchdog/lantiq_wdt.c
blob: 2e74c3a8ee5840ff405ded8932f32c6be6ea9d3e (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
/*
 *  This program is free software; you can redistribute it and/or modify it
 *  under the terms of the GNU General Public License version 2 as published
 *  by the Free Software Foundation.
 *
 *  Copyright (C) 2010 John Crispin <blogic@openwrt.org>
 *  Based on EP93xx wdt driver
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/module.h>
#include <linux/fs.h>
#include <linux/miscdevice.h>
#include <linux/watchdog.h>
#include <linux/of_platform.h>
#include <linux/uaccess.h>
#include <linux/clk.h>
#include <linux/io.h>

#include <lantiq_soc.h>

/*
 * Section 3.4 of the datasheet
 * The password sequence protects the WDT control register from unintended
 * write actions, which might cause malfunction of the WDT.
 *
 * essentially the following two magic passwords need to be written to allow
 * IO access to the WDT core
 */
#define LTQ_WDT_PW1		0x00BE0000
#define LTQ_WDT_PW2		0x00DC0000

#define LTQ_WDT_CR		0x0	/* watchdog control register */
#define LTQ_WDT_SR		0x8	/* watchdog status register */

#define LTQ_WDT_SR_EN		(0x1 << 31)	/* enable bit */
#define LTQ_WDT_SR_PWD		(0x3 << 26)	/* turn on power */
#define LTQ_WDT_SR_CLKDIV	(0x3 << 24)	/* turn on clock and set */
						/* divider to 0x40000 */
#define LTQ_WDT_DIVIDER		0x40000
#define LTQ_MAX_TIMEOUT		((1 << 16) - 1)	/* the reload field is 16 bit */

static bool nowayout = WATCHDOG_NOWAYOUT;

static void __iomem *ltq_wdt_membase;
static unsigned long ltq_io_region_clk_rate;

static unsigned long ltq_wdt_bootstatus;
static unsigned long ltq_wdt_in_use;
static int ltq_wdt_timeout = 30;
static int ltq_wdt_ok_to_close;

static void
ltq_wdt_enable(void)
{
	unsigned long int timeout = ltq_wdt_timeout *
			(ltq_io_region_clk_rate / LTQ_WDT_DIVIDER) + 0x1000;
	if (timeout > LTQ_MAX_TIMEOUT)
		timeout = LTQ_MAX_TIMEOUT;

	/* write the first password magic */
	ltq_w32(LTQ_WDT_PW1, ltq_wdt_membase + LTQ_WDT_CR);
	/* write the second magic plus the configuration and new timeout */
	ltq_w32(LTQ_WDT_SR_EN | LTQ_WDT_SR_PWD | LTQ_WDT_SR_CLKDIV |
		LTQ_WDT_PW2 | timeout, ltq_wdt_membase + LTQ_WDT_CR);
}

static void
ltq_wdt_disable(void)
{
	/* write the first password magic */
	ltq_w32(LTQ_WDT_PW1, ltq_wdt_membase + LTQ_WDT_CR);
	/*
	 * write the second password magic with no config
	 * this turns the watchdog off
	 */
	ltq_w32(LTQ_WDT_PW2, ltq_wdt_membase + LTQ_WDT_CR);
}

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

			ltq_wdt_ok_to_close = 0;
			for (i = 0; i != len; i++) {
				char c;

				if (get_user(c, data + i))
					return -EFAULT;
				if (c == 'V')
					ltq_wdt_ok_to_close = 1;
				else
					ltq_wdt_ok_to_close = 0;
			}
		}
		ltq_wdt_enable();
	}

	return len;
}

static struct watchdog_info ident = {
	.options = WDIOF_MAGICCLOSE | WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING |
			WDIOF_CARDRESET,
	.identity = "ltq_wdt",
};

static long
ltq_wdt_ioctl(struct file *file,
		unsigned int cmd, unsigned long arg)
{
	int ret = -ENOTTY;

	switch (cmd) {
	case WDIOC_GETSUPPORT:
		ret = copy_to_user((struct watchdog_info __user *)arg, &ident,
				sizeof(ident)) ? -EFAULT : 0;
		break;

	case WDIOC_GETBOOTSTATUS:
		ret = put_user(ltq_wdt_bootstatus, (int __user *)arg);
		break;

	case WDIOC_GETSTATUS:
		ret = put_user(0, (int __user *)arg);
		break;

	case WDIOC_SETTIMEOUT:
		ret = get_user(ltq_wdt_timeout, (int __user *)arg);
		if (!ret)
			ltq_wdt_enable();
		/* intentional drop through */
	case WDIOC_GETTIMEOUT:
		ret = put_user(ltq_wdt_timeout, (int __user *)arg);
		break;

	case WDIOC_KEEPALIVE:
		ltq_wdt_enable();
		ret = 0;
		break;
	}
	return ret;
}

static int
ltq_wdt_open(struct inode *inode, struct file *file)
{
	if (test_and_set_bit(0, &ltq_wdt_in_use))
		return -EBUSY;
	ltq_wdt_in_use = 1;
	ltq_wdt_enable();

	return nonseekable_open(inode, file);
}

static int
ltq_wdt_release(struct inode *inode, struct file *file)
{
	if (ltq_wdt_ok_to_close)
		ltq_wdt_disable();
	else
		pr_err("watchdog closed without warning\n");
	ltq_wdt_ok_to_close = 0;
	clear_bit(0, &ltq_wdt_in_use);

	return 0;
}

static const struct file_operations ltq_wdt_fops = {
	.owner		= THIS_MODULE,
	.write		= ltq_wdt_write,
	.unlocked_ioctl	= ltq_wdt_ioctl,
	.open		= ltq_wdt_open,
	.release	= ltq_wdt_release,
	.llseek		= no_llseek,
};

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

static int __devinit
ltq_wdt_probe(struct platform_device *pdev)
{
	struct resource *res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	struct clk *clk;

	if (!res) {
		dev_err(&pdev->dev, "cannot obtain I/O memory region");
		return -ENOENT;
	}

	ltq_wdt_membase = devm_request_and_ioremap(&pdev->dev, res);
	if (!ltq_wdt_membase) {
		dev_err(&pdev->dev, "cannot remap I/O memory region\n");
		return -ENOMEM;
	}

	/* we do not need to enable the clock as it is always running */
	clk = clk_get_io();
	if (IS_ERR(clk)) {
		dev_err(&pdev->dev, "Failed to get clock\n");
		return -ENOENT;
	}
	ltq_io_region_clk_rate = clk_get_rate(clk);
	clk_put(clk);

	/* find out if the watchdog caused the last reboot */
	if (ltq_reset_cause() == LTQ_RST_CAUSE_WDTRST)
		ltq_wdt_bootstatus = WDIOF_CARDRESET;

	dev_info(&pdev->dev, "Init done\n");
	return misc_register(&ltq_wdt_miscdev);
}

static int __devexit
ltq_wdt_remove(struct platform_device *pdev)
{
	misc_deregister(&ltq_wdt_miscdev);

	return 0;
}

static const struct of_device_id ltq_wdt_match[] = {
	{ .compatible = "lantiq,wdt" },
	{},
};
MODULE_DEVICE_TABLE(of, ltq_wdt_match);

static struct platform_driver ltq_wdt_driver = {
	.probe = ltq_wdt_probe,
	.remove = __devexit_p(ltq_wdt_remove),
	.driver = {
		.name = "wdt",
		.owner = THIS_MODULE,
		.of_match_table = ltq_wdt_match,
	},
};

module_platform_driver(ltq_wdt_driver);

module_param(nowayout, bool, 0);
MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started");
MODULE_AUTHOR("John Crispin <blogic@openwrt.org>");
MODULE_DESCRIPTION("Lantiq SoC Watchdog");
MODULE_LICENSE("GPL");
MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);