1/*
2 * Watchdog driver for Cirrus Logic EP93xx family of devices.
3 *
4 * Copyright (c) 2004 Ray Lehtiniemi
5 * Copyright (c) 2006 Tower Technologies
6 * Based on ep93xx driver, bits from alim7101_wdt.c
7 *
8 * Authors: Ray Lehtiniemi <rayl@mail.com>,
9 *	Alessandro Zummo <a.zummo@towertech.it>
10 *
11 * This file is licensed under the terms of the GNU General Public
12 * License version 2. This program is licensed "as is" without any
13 * warranty of any kind, whether express or implied.
14 *
15 * This watchdog fires after 250msec, which is a too short interval
16 * for us to rely on the user space daemon alone. So we ping the
17 * wdt each ~200msec and eventually stop doing it if the user space
18 * daemon dies.
19 *
20 * TODO:
21 *
22 *	- Test last reset from watchdog status
23 *	- Add a few missing ioctls
24 */
25
26#include <linux/module.h>
27#include <linux/fs.h>
28#include <linux/miscdevice.h>
29#include <linux/watchdog.h>
30#include <linux/timer.h>
31
32#include <asm/hardware.h>
33#include <asm/uaccess.h>
34
35#define WDT_VERSION	"0.3"
36#define PFX		"ep93xx_wdt: "
37
38/* default timeout (secs) */
39#define WDT_TIMEOUT 30
40
41static int nowayout = WATCHDOG_NOWAYOUT;
42static int timeout = WDT_TIMEOUT;
43
44static struct timer_list timer;
45static unsigned long next_heartbeat;
46static unsigned long wdt_status;
47static unsigned long boot_status;
48
49#define WDT_IN_USE		0
50#define WDT_OK_TO_CLOSE		1
51
52#define EP93XX_WDT_REG(x)	(EP93XX_WATCHDOG_BASE + (x))
53#define EP93XX_WDT_WATCHDOG	EP93XX_WDT_REG(0x00)
54#define EP93XX_WDT_WDSTATUS	EP93XX_WDT_REG(0x04)
55
56/* reset the wdt every ~200ms */
57#define WDT_INTERVAL (HZ/5)
58
59static void wdt_enable(void)
60{
61	__raw_writew(0xaaaa, EP93XX_WDT_WATCHDOG);
62}
63
64static void wdt_disable(void)
65{
66	__raw_writew(0xaa55, EP93XX_WDT_WATCHDOG);
67}
68
69static inline void wdt_ping(void)
70{
71	__raw_writew(0x5555, EP93XX_WDT_WATCHDOG);
72}
73
74static void wdt_startup(void)
75{
76	next_heartbeat = jiffies + (timeout * HZ);
77
78	wdt_enable();
79	mod_timer(&timer, jiffies + WDT_INTERVAL);
80}
81
82static void wdt_shutdown(void)
83{
84	del_timer_sync(&timer);
85	wdt_disable();
86}
87
88static void wdt_keepalive(void)
89{
90	/* user land ping */
91	next_heartbeat = jiffies + (timeout * HZ);
92}
93
94static int ep93xx_wdt_open(struct inode *inode, struct file *file)
95{
96	if (test_and_set_bit(WDT_IN_USE, &wdt_status))
97		return -EBUSY;
98
99	clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
100
101	wdt_startup();
102
103	return nonseekable_open(inode, file);
104}
105
106static ssize_t
107ep93xx_wdt_write(struct file *file, const char __user *data, size_t len,
108		 loff_t *ppos)
109{
110	/* Can't seek (pwrite) on this device */
111	if (*ppos != file->f_pos)
112		return -ESPIPE;
113
114	if (len) {
115		if (!nowayout) {
116			size_t i;
117
118			clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
119
120			for (i = 0; i != len; i++) {
121				char c;
122
123				if (get_user(c, data + i))
124					return -EFAULT;
125
126				if (c == 'V')
127					set_bit(WDT_OK_TO_CLOSE, &wdt_status);
128				else
129					clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
130			}
131		}
132		wdt_keepalive();
133	}
134
135	return len;
136}
137
138static struct watchdog_info ident = {
139	.options = WDIOF_CARDRESET | WDIOF_MAGICCLOSE,
140	.identity = "EP93xx Watchdog",
141};
142
143static int
144ep93xx_wdt_ioctl(struct inode *inode, struct file *file, unsigned int cmd,
145		 unsigned long arg)
146{
147	int ret = -ENOTTY;
148
149	switch (cmd) {
150	case WDIOC_GETSUPPORT:
151		ret = copy_to_user((struct watchdog_info __user *)arg, &ident,
152				sizeof(ident)) ? -EFAULT : 0;
153		break;
154
155	case WDIOC_GETSTATUS:
156		ret = put_user(0, (int __user *)arg);
157		break;
158
159	case WDIOC_GETBOOTSTATUS:
160		ret = put_user(boot_status, (int __user *)arg);
161		break;
162
163	case WDIOC_GETTIMEOUT:
164		/* actually, it is 0.250 seconds.... */
165		ret = put_user(1, (int __user *)arg);
166		break;
167
168	case WDIOC_KEEPALIVE:
169		wdt_keepalive();
170		ret = 0;
171		break;
172	}
173	return ret;
174}
175
176static int ep93xx_wdt_release(struct inode *inode, struct file *file)
177{
178	if (test_bit(WDT_OK_TO_CLOSE, &wdt_status))
179		wdt_shutdown();
180	else
181		printk(KERN_CRIT PFX "Device closed unexpectedly - "
182			"timer will not stop\n");
183
184	clear_bit(WDT_IN_USE, &wdt_status);
185	clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
186
187	return 0;
188}
189
190static const struct file_operations ep93xx_wdt_fops = {
191	.owner		= THIS_MODULE,
192	.write		= ep93xx_wdt_write,
193	.ioctl		= ep93xx_wdt_ioctl,
194	.open		= ep93xx_wdt_open,
195	.release	= ep93xx_wdt_release,
196};
197
198static struct miscdevice ep93xx_wdt_miscdev = {
199	.minor		= WATCHDOG_MINOR,
200	.name		= "watchdog",
201	.fops		= &ep93xx_wdt_fops,
202};
203
204static void ep93xx_timer_ping(unsigned long data)
205{
206	if (time_before(jiffies, next_heartbeat))
207		wdt_ping();
208
209	/* Re-set the timer interval */
210	mod_timer(&timer, jiffies + WDT_INTERVAL);
211}
212
213static int __init ep93xx_wdt_init(void)
214{
215	int err;
216
217	err = misc_register(&ep93xx_wdt_miscdev);
218
219	boot_status = __raw_readl(EP93XX_WDT_WATCHDOG) & 0x01 ? 1 : 0;
220
221	printk(KERN_INFO PFX "EP93XX watchdog, driver version "
222		WDT_VERSION "%s\n",
223		(__raw_readl(EP93XX_WDT_WATCHDOG) & 0x08)
224		? " (nCS1 disable detected)" : "");
225
226	if (timeout < 1 || timeout > 3600) {
227		timeout = WDT_TIMEOUT;
228		printk(KERN_INFO PFX
229			"timeout value must be 1<=x<=3600, using %d\n",
230			timeout);
231	}
232
233	setup_timer(&timer, ep93xx_timer_ping, 1);
234	return err;
235}
236
237static void __exit ep93xx_wdt_exit(void)
238{
239	wdt_shutdown();
240	misc_deregister(&ep93xx_wdt_miscdev);
241}
242
243module_init(ep93xx_wdt_init);
244module_exit(ep93xx_wdt_exit);
245
246module_param(nowayout, int, 0);
247MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started");
248
249module_param(timeout, int, 0);
250MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds. (1<=timeout<=3600, default=" __MODULE_STRING(WATCHDOG_TIMEOUT) ")");
251
252MODULE_AUTHOR("Ray Lehtiniemi <rayl@mail.com>,"
253		"Alessandro Zummo <a.zummo@towertech.it>");
254MODULE_DESCRIPTION("EP93xx Watchdog");
255MODULE_LICENSE("GPL");
256MODULE_VERSION(WDT_VERSION);
257MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
258