1 /*
2 * mpc83xx_wdt.c - MPC83xx watchdog userspace interface
3 *
4 * Authors: Dave Updegraff <dave@cray.org>
5 * Kumar Gala <galak@kernel.crashing.org>
6 * Attribution: from 83xx_wst: Florian Schirmer <jolt@tuxbox.org>
7 * ..and from sc520_wdt
8 *
9 * Note: it appears that you can only actually ENABLE or DISABLE the thing
10 * once after POR. Once enabled, you cannot disable, and vice versa.
11 *
12 * This program is free software; you can redistribute it and/or modify it
13 * under the terms of the GNU General Public License as published by the
14 * Free Software Foundation; either version 2 of the License, or (at your
15 * option) any later version.
16 */
17
18 #include <linux/fs.h>
19 #include <linux/init.h>
20 #include <linux/kernel.h>
21 #include <linux/miscdevice.h>
22 #include <linux/platform_device.h>
23 #include <linux/module.h>
24 #include <linux/watchdog.h>
25 #include <asm/io.h>
26 #include <asm/uaccess.h>
27
28 struct mpc83xx_wdt {
29 __be32 res0;
30 __be32 swcrr; /* System watchdog control register */
31 #define SWCRR_SWTC 0xFFFF0000 /* Software Watchdog Time Count. */
32 #define SWCRR_SWEN 0x00000004 /* Watchdog Enable bit. */
33 #define SWCRR_SWRI 0x00000002 /* Software Watchdog Reset/Interrupt Select bit.*/
34 #define SWCRR_SWPR 0x00000001 /* Software Watchdog Counter Prescale bit. */
35 __be32 swcnr; /* System watchdog count register */
36 u8 res1[2];
37 __be16 swsrr; /* System watchdog service register */
38 u8 res2[0xF0];
39 };
40
41 static struct mpc83xx_wdt __iomem *wd_base;
42
43 static u16 timeout = 0xffff;
44 module_param(timeout, ushort, 0);
45 MODULE_PARM_DESC(timeout, "Watchdog timeout in ticks. (0<timeout<65536, default=65535");
46
47 static int reset = 1;
48 module_param(reset, bool, 0);
49 MODULE_PARM_DESC(reset, "Watchdog Interrupt/Reset Mode. 0 = interrupt, 1 = reset");
50
51 /*
52 * We always prescale, but if someone really doesn't want to they can set this
53 * to 0
54 */
55 static int prescale = 1;
56 static unsigned int timeout_sec;
57
58 static unsigned long wdt_is_open;
59 static DEFINE_SPINLOCK(wdt_spinlock);
60
61 static void mpc83xx_wdt_keepalive(void)
62 {
63 /* Ping the WDT */
64 spin_lock(&wdt_spinlock);
65 out_be16(&wd_base->swsrr, 0x556c);
66 out_be16(&wd_base->swsrr, 0xaa39);
67 spin_unlock(&wdt_spinlock);
68 }
69
70 static ssize_t mpc83xx_wdt_write(struct file *file, const char __user *buf,
71 size_t count, loff_t *ppos)
72 {
73 if (count)
74 mpc83xx_wdt_keepalive();
75 return count;
76 }
77
78 static int mpc83xx_wdt_open(struct inode *inode, struct file *file)
79 {
80 u32 tmp = SWCRR_SWEN;
81 if (test_and_set_bit(0, &wdt_is_open))
82 return -EBUSY;
83
84 /* Once we start the watchdog we can't stop it */
85 __module_get(THIS_MODULE);
86
87 /* Good, fire up the show */
88 if (prescale)
89 tmp |= SWCRR_SWPR;
90 if (reset)
91 tmp |= SWCRR_SWRI;
92
93 tmp |= timeout << 16;
94
95 out_be32(&wd_base->swcrr, tmp);
96
97 return nonseekable_open(inode, file);
98 }
99
100 static int mpc83xx_wdt_release(struct inode *inode, struct file *file)
101 {
102 printk(KERN_CRIT "Unexpected close, not stopping watchdog!\n");
103 mpc83xx_wdt_keepalive();
104 clear_bit(0, &wdt_is_open);
105 return 0;
106 }
107
108 static int mpc83xx_wdt_ioctl(struct inode *inode, struct file *file,
109 unsigned int cmd, unsigned long arg)
110 {
111 void __user *argp = (void __user *)arg;
112 int __user *p = argp;
113 static struct watchdog_info ident = {
114 .options = WDIOF_KEEPALIVEPING,
115 .firmware_version = 1,
116 .identity = "MPC83xx",
117 };
118
119 switch (cmd) {
120 case WDIOC_GETSUPPORT:
121 return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
122 case WDIOC_GETSTATUS:
123 case WDIOC_GETBOOTSTATUS:
124 return put_user(0, p);
125 case WDIOC_KEEPALIVE:
126 mpc83xx_wdt_keepalive();
127 return 0;
128 case WDIOC_GETTIMEOUT:
129 return put_user(timeout_sec, p);
130 default:
131 return -ENOTTY;
132 }
133 }
134
135 static const struct file_operations mpc83xx_wdt_fops = {
136 .owner = THIS_MODULE,
137 .llseek = no_llseek,
138 .write = mpc83xx_wdt_write,
139 .ioctl = mpc83xx_wdt_ioctl,
140 .open = mpc83xx_wdt_open,
141 .release = mpc83xx_wdt_release,
142 };
143
144 static struct miscdevice mpc83xx_wdt_miscdev = {
145 .minor = WATCHDOG_MINOR,
146 .name = "watchdog",
147 .fops = &mpc83xx_wdt_fops,
148 };
149
150 static int __devinit mpc83xx_wdt_probe(struct platform_device *dev)
151 {
152 struct resource *r;
153 int ret;
154 unsigned int *freq = dev->dev.platform_data;
155
156 /* get a pointer to the register memory */
157 r = platform_get_resource(dev, IORESOURCE_MEM, 0);
158
159 if (!r) {
160 ret = -ENODEV;
161 goto err_out;
162 }
163
164 wd_base = ioremap(r->start, sizeof (struct mpc83xx_wdt));
165
166 if (wd_base == NULL) {
167 ret = -ENOMEM;
168 goto err_out;
169 }
170
171 ret = misc_register(&mpc83xx_wdt_miscdev);
172 if (ret) {
173 printk(KERN_ERR "cannot register miscdev on minor=%d "
174 "(err=%d)\n",
175 WATCHDOG_MINOR, ret);
176 goto err_unmap;
177 }
178
179 /* Calculate the timeout in seconds */
180 if (prescale)
181 timeout_sec = (timeout * 0x10000) / (*freq);
182 else
183 timeout_sec = timeout / (*freq);
184
185 printk(KERN_INFO "WDT driver for MPC83xx initialized. "
186 "mode:%s timeout=%d (%d seconds)\n",
187 reset ? "reset":"interrupt", timeout, timeout_sec);
188 return 0;
189
190 err_unmap:
191 iounmap(wd_base);
192 err_out:
193 return ret;
194 }
195
196 static int __devexit mpc83xx_wdt_remove(struct platform_device *dev)
197 {
198 misc_deregister(&mpc83xx_wdt_miscdev);
199 iounmap(wd_base);
200
201 return 0;
202 }
203
204 static struct platform_driver mpc83xx_wdt_driver = {
205 .probe = mpc83xx_wdt_probe,
206 .remove = __devexit_p(mpc83xx_wdt_remove),
207 .driver = {
208 .name = "mpc83xx_wdt",
209 .owner = THIS_MODULE,
210 },
211 };
212
213 static int __init mpc83xx_wdt_init(void)
214 {
215 return platform_driver_register(&mpc83xx_wdt_driver);
216 }
217
218 static void __exit mpc83xx_wdt_exit(void)
219 {
220 platform_driver_unregister(&mpc83xx_wdt_driver);
221 }
222
223 module_init(mpc83xx_wdt_init);
224 module_exit(mpc83xx_wdt_exit);
225
226 MODULE_AUTHOR("Dave Updegraff, Kumar Gala");
227 MODULE_DESCRIPTION("Driver for watchdog timer in MPC83xx uProcessor");
228 MODULE_LICENSE("GPL");
229 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
230 MODULE_ALIAS("platform:mpc83xx_wdt");
231
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