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Alessandro Zummof52ac8f2006-03-25 03:06:37 -08001/*
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>
Alan Coxf339e2a2008-05-19 14:05:35 +010031#include <linux/uaccess.h>
Ryan Mallon2653d1d2009-07-15 21:33:22 +010032#include <linux/io.h>
Russell Kinga09e64f2008-08-05 16:14:15 +010033#include <mach/hardware.h>
Alessandro Zummof52ac8f2006-03-25 03:06:37 -080034
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{
Alessandro Zummof52ac8f2006-03-25 03:06:37 -0800110 if (len) {
111 if (!nowayout) {
112 size_t i;
113
114 clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
115
116 for (i = 0; i != len; i++) {
117 char c;
118
119 if (get_user(c, data + i))
120 return -EFAULT;
121
122 if (c == 'V')
123 set_bit(WDT_OK_TO_CLOSE, &wdt_status);
124 else
125 clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
126 }
127 }
128 wdt_keepalive();
129 }
130
131 return len;
132}
133
134static struct watchdog_info ident = {
135 .options = WDIOF_CARDRESET | WDIOF_MAGICCLOSE,
136 .identity = "EP93xx Watchdog",
137};
138
Alan Coxf339e2a2008-05-19 14:05:35 +0100139static long ep93xx_wdt_ioctl(struct file *file,
140 unsigned int cmd, unsigned long arg)
Alessandro Zummof52ac8f2006-03-25 03:06:37 -0800141{
Samuel Tardieu795b89d2006-09-09 17:34:31 +0200142 int ret = -ENOTTY;
Alessandro Zummof52ac8f2006-03-25 03:06:37 -0800143
144 switch (cmd) {
145 case WDIOC_GETSUPPORT:
146 ret = copy_to_user((struct watchdog_info __user *)arg, &ident,
147 sizeof(ident)) ? -EFAULT : 0;
148 break;
149
150 case WDIOC_GETSTATUS:
151 ret = put_user(0, (int __user *)arg);
152 break;
153
154 case WDIOC_GETBOOTSTATUS:
155 ret = put_user(boot_status, (int __user *)arg);
156 break;
157
Alessandro Zummof52ac8f2006-03-25 03:06:37 -0800158 case WDIOC_KEEPALIVE:
159 wdt_keepalive();
160 ret = 0;
161 break;
Wim Van Sebroeck0c060902008-07-18 11:41:17 +0000162
163 case WDIOC_GETTIMEOUT:
164 /* actually, it is 0.250 seconds.... */
165 ret = put_user(1, (int __user *)arg);
166 break;
Alessandro Zummof52ac8f2006-03-25 03:06:37 -0800167 }
168 return ret;
169}
170
171static int ep93xx_wdt_release(struct inode *inode, struct file *file)
172{
173 if (test_bit(WDT_OK_TO_CLOSE, &wdt_status))
174 wdt_shutdown();
175 else
Alan Coxf339e2a2008-05-19 14:05:35 +0100176 printk(KERN_CRIT PFX
177 "Device closed unexpectedly - timer will not stop\n");
Alessandro Zummof52ac8f2006-03-25 03:06:37 -0800178
179 clear_bit(WDT_IN_USE, &wdt_status);
180 clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
181
182 return 0;
183}
184
Arjan van de Ven62322d22006-07-03 00:24:21 -0700185static const struct file_operations ep93xx_wdt_fops = {
Alessandro Zummof52ac8f2006-03-25 03:06:37 -0800186 .owner = THIS_MODULE,
187 .write = ep93xx_wdt_write,
Alan Coxf339e2a2008-05-19 14:05:35 +0100188 .unlocked_ioctl = ep93xx_wdt_ioctl,
Alessandro Zummof52ac8f2006-03-25 03:06:37 -0800189 .open = ep93xx_wdt_open,
190 .release = ep93xx_wdt_release,
191};
192
193static struct miscdevice ep93xx_wdt_miscdev = {
194 .minor = WATCHDOG_MINOR,
195 .name = "watchdog",
196 .fops = &ep93xx_wdt_fops,
197};
198
199static void ep93xx_timer_ping(unsigned long data)
200{
201 if (time_before(jiffies, next_heartbeat))
202 wdt_ping();
203
204 /* Re-set the timer interval */
205 mod_timer(&timer, jiffies + WDT_INTERVAL);
206}
207
208static int __init ep93xx_wdt_init(void)
209{
210 int err;
211
212 err = misc_register(&ep93xx_wdt_miscdev);
213
214 boot_status = __raw_readl(EP93XX_WDT_WATCHDOG) & 0x01 ? 1 : 0;
215
216 printk(KERN_INFO PFX "EP93XX watchdog, driver version "
217 WDT_VERSION "%s\n",
218 (__raw_readl(EP93XX_WDT_WATCHDOG) & 0x08)
219 ? " (nCS1 disable detected)" : "");
220
221 if (timeout < 1 || timeout > 3600) {
222 timeout = WDT_TIMEOUT;
223 printk(KERN_INFO PFX
224 "timeout value must be 1<=x<=3600, using %d\n",
225 timeout);
226 }
227
228 setup_timer(&timer, ep93xx_timer_ping, 1);
229 return err;
230}
231
232static void __exit ep93xx_wdt_exit(void)
233{
234 wdt_shutdown();
235 misc_deregister(&ep93xx_wdt_miscdev);
236}
237
238module_init(ep93xx_wdt_init);
239module_exit(ep93xx_wdt_exit);
240
241module_param(nowayout, int, 0);
242MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started");
243
244module_param(timeout, int, 0);
Alan Coxf339e2a2008-05-19 14:05:35 +0100245MODULE_PARM_DESC(timeout,
246 "Watchdog timeout in seconds. (1<=timeout<=3600, default="
247 __MODULE_STRING(WATCHDOG_TIMEOUT) ")");
Alessandro Zummof52ac8f2006-03-25 03:06:37 -0800248
249MODULE_AUTHOR("Ray Lehtiniemi <rayl@mail.com>,"
250 "Alessandro Zummo <a.zummo@towertech.it>");
251MODULE_DESCRIPTION("EP93xx Watchdog");
252MODULE_LICENSE("GPL");
253MODULE_VERSION(WDT_VERSION);
254MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);