1 /*
2 * mpc8xxx_wdt.c - MPC8xx/MPC83xx/MPC86xx 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 * Copyright (c) 2008 MontaVista Software, Inc.
9 * Anton Vorontsov <avorontsov@ru.mvista.com>
10 *
11 * Note: it appears that you can only actually ENABLE or DISABLE the thing
12 * once after POR. Once enabled, you cannot disable, and vice versa.
13 *
14 * This program is free software; you can redistribute it and/or modify it
15 * under the terms of the GNU General Public License as published by the
16 * Free Software Foundation; either version 2 of the License, or (at your
17 * option) any later version.
18 */
19
20 #include <linux/fs.h>
21 #include <linux/init.h>
22 #include <linux/kernel.h>
23 #include <linux/timer.h>
24 #include <linux/miscdevice.h>
25 #include <linux/of_platform.h>
26 #include <linux/module.h>
27 #include <linux/watchdog.h>
28 #include <linux/io.h>
29 #include <linux/uaccess.h>
30 #include <sysdev/fsl_soc.h>
31
32 struct mpc8xxx_wdt {
33 __be32 res0;
34 __be32 swcrr; /* System watchdog control register */
35 #define SWCRR_SWTC 0xFFFF0000 /* Software Watchdog Time Count. */
36 #define SWCRR_SWEN 0x00000004 /* Watchdog Enable bit. */
37 #define SWCRR_SWRI 0x00000002 /* Software Watchdog Reset/Interrupt Select bit.*/
38 #define SWCRR_SWPR 0x00000001 /* Software Watchdog Counter Prescale bit. */
39 __be32 swcnr; /* System watchdog count register */
40 u8 res1[2];
41 __be16 swsrr; /* System watchdog service register */
42 u8 res2[0xF0];
43 };
44
45 struct mpc8xxx_wdt_type {
46 int prescaler;
47 bool hw_enabled;
48 };
49
50 static struct mpc8xxx_wdt __iomem *wd_base;
51 static int mpc8xxx_wdt_init_late(void);
52
53 static u16 timeout = 0xffff;
54 module_param(timeout, ushort, 0);
55 MODULE_PARM_DESC(timeout,
56 "Watchdog timeout in ticks. (0<timeout<65536, default=65535");
57
58 static int reset = 1;
59 module_param(reset, bool, 0);
60 MODULE_PARM_DESC(reset,
61 "Watchdog Interrupt/Reset Mode. 0 = interrupt, 1 = reset");
62
63 static int nowayout = WATCHDOG_NOWAYOUT;
64 module_param(nowayout, int, 0);
65 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started "
66 "(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
67
68 /*
69 * We always prescale, but if someone really doesn't want to they can set this
70 * to 0
71 */
72 static int prescale = 1;
73 static unsigned int timeout_sec;
74
75 static unsigned long wdt_is_open;
76 static DEFINE_SPINLOCK(wdt_spinlock);
77
78 static void mpc8xxx_wdt_keepalive(void)
79 {
80 /* Ping the WDT */
81 spin_lock(&wdt_spinlock);
82 out_be16(&wd_base->swsrr, 0x556c);
83 out_be16(&wd_base->swsrr, 0xaa39);
84 spin_unlock(&wdt_spinlock);
85 }
86
87 static void mpc8xxx_wdt_timer_ping(unsigned long arg);
88 static DEFINE_TIMER(wdt_timer, mpc8xxx_wdt_timer_ping, 0, 0);
89
90 static void mpc8xxx_wdt_timer_ping(unsigned long arg)
91 {
92 mpc8xxx_wdt_keepalive();
93 /* We're pinging it twice faster than needed, just to be sure. */
94 mod_timer(&wdt_timer, jiffies + HZ * timeout_sec / 2);
95 }
96
97 static void mpc8xxx_wdt_pr_warn(const char *msg)
98 {
99 pr_crit("mpc8xxx_wdt: %s, expect the %s soon!\n", msg,
100 reset ? "reset" : "machine check exception");
101 }
102
103 static ssize_t mpc8xxx_wdt_write(struct file *file, const char __user *buf,
104 size_t count, loff_t *ppos)
105 {
106 if (count)
107 mpc8xxx_wdt_keepalive();
108 return count;
109 }
110
111 static int mpc8xxx_wdt_open(struct inode *inode, struct file *file)
112 {
113 u32 tmp = SWCRR_SWEN;
114 if (test_and_set_bit(0, &wdt_is_open))
115 return -EBUSY;
116
117 /* Once we start the watchdog we can't stop it */
118 if (nowayout)
119 __module_get(THIS_MODULE);
120
121 /* Good, fire up the show */
122 if (prescale)
123 tmp |= SWCRR_SWPR;
124 if (reset)
125 tmp |= SWCRR_SWRI;
126
127 tmp |= timeout << 16;
128
129 out_be32(&wd_base->swcrr, tmp);
130
131 del_timer_sync(&wdt_timer);
132
133 return nonseekable_open(inode, file);
134 }
135
136 static int mpc8xxx_wdt_release(struct inode *inode, struct file *file)
137 {
138 if (!nowayout)
139 mpc8xxx_wdt_timer_ping(0);
140 else
141 mpc8xxx_wdt_pr_warn("watchdog closed");
142 clear_bit(0, &wdt_is_open);
143 return 0;
144 }
145
146 static long mpc8xxx_wdt_ioctl(struct file *file, unsigned int cmd,
147 unsigned long arg)
148 {
149 void __user *argp = (void __user *)arg;
150 int __user *p = argp;
151 static struct watchdog_info ident = {
152 .options = WDIOF_KEEPALIVEPING,
153 .firmware_version = 1,
154 .identity = "MPC8xxx",
155 };
156
157 switch (cmd) {
158 case WDIOC_GETSUPPORT:
159 return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
160 case WDIOC_GETSTATUS:
161 case WDIOC_GETBOOTSTATUS:
162 return put_user(0, p);
163 case WDIOC_KEEPALIVE:
164 mpc8xxx_wdt_keepalive();
165 return 0;
166 case WDIOC_GETTIMEOUT:
167 return put_user(timeout_sec, p);
168 default:
169 return -ENOTTY;
170 }
171 }
172
173 static const struct file_operations mpc8xxx_wdt_fops = {
174 .owner = THIS_MODULE,
175 .llseek = no_llseek,
176 .write = mpc8xxx_wdt_write,
177 .unlocked_ioctl = mpc8xxx_wdt_ioctl,
178 .open = mpc8xxx_wdt_open,
179 .release = mpc8xxx_wdt_release,
180 };
181
182 static struct miscdevice mpc8xxx_wdt_miscdev = {
183 .minor = WATCHDOG_MINOR,
184 .name = "watchdog",
185 .fops = &mpc8xxx_wdt_fops,
186 };
187
188 static int __devinit mpc8xxx_wdt_probe(struct of_device *ofdev,
189 const struct of_device_id *match)
190 {
191 int ret;
192 struct device_node *np = ofdev->node;
193 struct mpc8xxx_wdt_type *wdt_type = match->data;
194 u32 freq = fsl_get_sys_freq();
195 bool enabled;
196
197 if (!freq || freq == -1)
198 return -EINVAL;
199
200 wd_base = of_iomap(np, 0);
201 if (!wd_base)
202 return -ENOMEM;
203
204 enabled = in_be32(&wd_base->swcrr) & SWCRR_SWEN;
205 if (!enabled && wdt_type->hw_enabled) {
206 pr_info("mpc8xxx_wdt: could not be enabled in software\n");
207 ret = -ENOSYS;
208 goto err_unmap;
209 }
210
211 /* Calculate the timeout in seconds */
212 if (prescale)
213 timeout_sec = (timeout * wdt_type->prescaler) / freq;
214 else
215 timeout_sec = timeout / freq;
216
217 #ifdef MODULE
218 ret = mpc8xxx_wdt_init_late();
219 if (ret)
220 goto err_unmap;
221 #endif
222
223 pr_info("WDT driver for MPC8xxx initialized. mode:%s timeout=%d "
224 "(%d seconds)\n", reset ? "reset" : "interrupt", timeout,
225 timeout_sec);
226
227 /*
228 * If the watchdog was previously enabled or we're running on
229 * MPC8xxx, we should ping the wdt from the kernel until the
230 * userspace handles it.
231 */
232 if (enabled)
233 mpc8xxx_wdt_timer_ping(0);
234 return 0;
235 err_unmap:
236 iounmap(wd_base);
237 wd_base = NULL;
238 return ret;
239 }
240
241 static int __devexit mpc8xxx_wdt_remove(struct of_device *ofdev)
242 {
243 mpc8xxx_wdt_pr_warn("watchdog removed");
244 del_timer_sync(&wdt_timer);
245 misc_deregister(&mpc8xxx_wdt_miscdev);
246 iounmap(wd_base);
247
248 return 0;
249 }
250
251 static const struct of_device_id mpc8xxx_wdt_match[] = {
252 {
253 .compatible = "mpc83xx_wdt",
254 .data = &(struct mpc8xxx_wdt_type) {
255 .prescaler = 0x10000,
256 },
257 },
258 {
259 .compatible = "fsl,mpc8610-wdt",
260 .data = &(struct mpc8xxx_wdt_type) {
261 .prescaler = 0x10000,
262 .hw_enabled = true,
263 },
264 },
265 {
266 .compatible = "fsl,mpc823-wdt",
267 .data = &(struct mpc8xxx_wdt_type) {
268 .prescaler = 0x800,
269 },
270 },
271 {},
272 };
273 MODULE_DEVICE_TABLE(of, mpc8xxx_wdt_match);
274
275 static struct of_platform_driver mpc8xxx_wdt_driver = {
276 .match_table = mpc8xxx_wdt_match,
277 .probe = mpc8xxx_wdt_probe,
278 .remove = __devexit_p(mpc8xxx_wdt_remove),
279 .driver = {
280 .name = "mpc8xxx_wdt",
281 .owner = THIS_MODULE,
282 },
283 };
284
285 /*
286 * We do wdt initialization in two steps: arch_initcall probes the wdt
287 * very early to start pinging the watchdog (misc devices are not yet
288 * available), and later module_init() just registers the misc device.
289 */
290 static int mpc8xxx_wdt_init_late(void)
291 {
292 int ret;
293
294 if (!wd_base)
295 return -ENODEV;
296
297 ret = misc_register(&mpc8xxx_wdt_miscdev);
298 if (ret) {
299 pr_err("cannot register miscdev on minor=%d (err=%d)\n",
300 WATCHDOG_MINOR, ret);
301 return ret;
302 }
303 return 0;
304 }
305 #ifndef MODULE
306 module_init(mpc8xxx_wdt_init_late);
307 #endif
308
309 static int __init mpc8xxx_wdt_init(void)
310 {
311 return of_register_platform_driver(&mpc8xxx_wdt_driver);
312 }
313 arch_initcall(mpc8xxx_wdt_init);
314
315 static void __exit mpc8xxx_wdt_exit(void)
316 {
317 of_unregister_platform_driver(&mpc8xxx_wdt_driver);
318 }
319 module_exit(mpc8xxx_wdt_exit);
320
321 MODULE_AUTHOR("Dave Updegraff, Kumar Gala");
322 MODULE_DESCRIPTION("Driver for watchdog timer in MPC8xx/MPC83xx/MPC86xx "
323 "uProcessors");
324 MODULE_LICENSE("GPL");
325 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
326
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