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mpc8xxx_wdt.c
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1 /*
2  * mpc8xxx_wdt.c - MPC8xx/MPC83xx/MPC86xx watchdog userspace interface
3  *
4  * Authors: Dave Updegraff <[email protected]>
5  * Kumar Gala <[email protected]>
6  * Attribution: from 83xx_wst: Florian Schirmer <[email protected]>
7  * ..and from sc520_wdt
8  * Copyright (c) 2008 MontaVista Software, Inc.
9  * Anton Vorontsov <[email protected]>
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 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
21 
22 #include <linux/fs.h>
23 #include <linux/init.h>
24 #include <linux/kernel.h>
25 #include <linux/timer.h>
26 #include <linux/miscdevice.h>
27 #include <linux/of_platform.h>
28 #include <linux/module.h>
29 #include <linux/watchdog.h>
30 #include <linux/io.h>
31 #include <linux/uaccess.h>
32 #include <sysdev/fsl_soc.h>
33 
34 struct mpc8xxx_wdt {
36  __be32 swcrr; /* System watchdog control register */
37 #define SWCRR_SWTC 0xFFFF0000 /* Software Watchdog Time Count. */
38 #define SWCRR_SWEN 0x00000004 /* Watchdog Enable bit. */
39 #define SWCRR_SWRI 0x00000002 /* Software Watchdog Reset/Interrupt Select bit.*/
40 #define SWCRR_SWPR 0x00000001 /* Software Watchdog Counter Prescale bit. */
41  __be32 swcnr; /* System watchdog count register */
42  u8 res1[2];
43  __be16 swsrr; /* System watchdog service register */
44  u8 res2[0xF0];
45 };
46 
48  int prescaler;
49  bool hw_enabled;
50 };
51 
52 static struct mpc8xxx_wdt __iomem *wd_base;
53 static int mpc8xxx_wdt_init_late(void);
54 
55 static u16 timeout = 0xffff;
56 module_param(timeout, ushort, 0);
57 MODULE_PARM_DESC(timeout,
58  "Watchdog timeout in ticks. (0<timeout<65536, default=65535)");
59 
60 static bool reset = 1;
61 module_param(reset, bool, 0);
62 MODULE_PARM_DESC(reset,
63  "Watchdog Interrupt/Reset Mode. 0 = interrupt, 1 = reset");
64 
65 static bool nowayout = WATCHDOG_NOWAYOUT;
66 module_param(nowayout, bool, 0);
67 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started "
68  "(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
69 
70 /*
71  * We always prescale, but if someone really doesn't want to they can set this
72  * to 0
73  */
74 static int prescale = 1;
75 static unsigned int timeout_sec;
76 
77 static unsigned long wdt_is_open;
78 static DEFINE_SPINLOCK(wdt_spinlock);
79 
80 static void mpc8xxx_wdt_keepalive(void)
81 {
82  /* Ping the WDT */
83  spin_lock(&wdt_spinlock);
84  out_be16(&wd_base->swsrr, 0x556c);
85  out_be16(&wd_base->swsrr, 0xaa39);
86  spin_unlock(&wdt_spinlock);
87 }
88 
89 static void mpc8xxx_wdt_timer_ping(unsigned long arg);
90 static DEFINE_TIMER(wdt_timer, mpc8xxx_wdt_timer_ping, 0, 0);
91 
92 static void mpc8xxx_wdt_timer_ping(unsigned long arg)
93 {
94  mpc8xxx_wdt_keepalive();
95  /* We're pinging it twice faster than needed, just to be sure. */
96  mod_timer(&wdt_timer, jiffies + HZ * timeout_sec / 2);
97 }
98 
99 static void mpc8xxx_wdt_pr_warn(const char *msg)
100 {
101  pr_crit("%s, expect the %s soon!\n", msg,
102  reset ? "reset" : "machine check exception");
103 }
104 
105 static ssize_t mpc8xxx_wdt_write(struct file *file, const char __user *buf,
106  size_t count, loff_t *ppos)
107 {
108  if (count)
109  mpc8xxx_wdt_keepalive();
110  return count;
111 }
112 
113 static int mpc8xxx_wdt_open(struct inode *inode, struct file *file)
114 {
115  u32 tmp = SWCRR_SWEN;
116  if (test_and_set_bit(0, &wdt_is_open))
117  return -EBUSY;
118 
119  /* Once we start the watchdog we can't stop it */
120  if (nowayout)
121  __module_get(THIS_MODULE);
122 
123  /* Good, fire up the show */
124  if (prescale)
125  tmp |= SWCRR_SWPR;
126  if (reset)
127  tmp |= SWCRR_SWRI;
128 
129  tmp |= timeout << 16;
130 
131  out_be32(&wd_base->swcrr, tmp);
132 
133  del_timer_sync(&wdt_timer);
134 
135  return nonseekable_open(inode, file);
136 }
137 
138 static int mpc8xxx_wdt_release(struct inode *inode, struct file *file)
139 {
140  if (!nowayout)
141  mpc8xxx_wdt_timer_ping(0);
142  else
143  mpc8xxx_wdt_pr_warn("watchdog closed");
144  clear_bit(0, &wdt_is_open);
145  return 0;
146 }
147 
148 static long mpc8xxx_wdt_ioctl(struct file *file, unsigned int cmd,
149  unsigned long arg)
150 {
151  void __user *argp = (void __user *)arg;
152  int __user *p = argp;
153  static const struct watchdog_info ident = {
154  .options = WDIOF_KEEPALIVEPING,
155  .firmware_version = 1,
156  .identity = "MPC8xxx",
157  };
158 
159  switch (cmd) {
160  case WDIOC_GETSUPPORT:
161  return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
162  case WDIOC_GETSTATUS:
163  case WDIOC_GETBOOTSTATUS:
164  return put_user(0, p);
165  case WDIOC_KEEPALIVE:
166  mpc8xxx_wdt_keepalive();
167  return 0;
168  case WDIOC_GETTIMEOUT:
169  return put_user(timeout_sec, p);
170  default:
171  return -ENOTTY;
172  }
173 }
174 
175 static const struct file_operations mpc8xxx_wdt_fops = {
176  .owner = THIS_MODULE,
177  .llseek = no_llseek,
178  .write = mpc8xxx_wdt_write,
179  .unlocked_ioctl = mpc8xxx_wdt_ioctl,
180  .open = mpc8xxx_wdt_open,
181  .release = mpc8xxx_wdt_release,
182 };
183 
184 static struct miscdevice mpc8xxx_wdt_miscdev = {
185  .minor = WATCHDOG_MINOR,
186  .name = "watchdog",
187  .fops = &mpc8xxx_wdt_fops,
188 };
189 
190 static const struct of_device_id mpc8xxx_wdt_match[];
191 static int __devinit mpc8xxx_wdt_probe(struct platform_device *ofdev)
192 {
193  int ret;
194  const struct of_device_id *match;
195  struct device_node *np = ofdev->dev.of_node;
196  const struct mpc8xxx_wdt_type *wdt_type;
198  bool enabled;
199 
200  match = of_match_device(mpc8xxx_wdt_match, &ofdev->dev);
201  if (!match)
202  return -EINVAL;
203  wdt_type = match->data;
204 
205  if (!freq || freq == -1)
206  return -EINVAL;
207 
208  wd_base = of_iomap(np, 0);
209  if (!wd_base)
210  return -ENOMEM;
211 
212  enabled = in_be32(&wd_base->swcrr) & SWCRR_SWEN;
213  if (!enabled && wdt_type->hw_enabled) {
214  pr_info("could not be enabled in software\n");
215  ret = -ENOSYS;
216  goto err_unmap;
217  }
218 
219  /* Calculate the timeout in seconds */
220  if (prescale)
221  timeout_sec = (timeout * wdt_type->prescaler) / freq;
222  else
223  timeout_sec = timeout / freq;
224 
225 #ifdef MODULE
226  ret = mpc8xxx_wdt_init_late();
227  if (ret)
228  goto err_unmap;
229 #endif
230 
231  pr_info("WDT driver for MPC8xxx initialized. mode:%s timeout=%d (%d seconds)\n",
232  reset ? "reset" : "interrupt", timeout, timeout_sec);
233 
234  /*
235  * If the watchdog was previously enabled or we're running on
236  * MPC8xxx, we should ping the wdt from the kernel until the
237  * userspace handles it.
238  */
239  if (enabled)
240  mpc8xxx_wdt_timer_ping(0);
241  return 0;
242 err_unmap:
243  iounmap(wd_base);
244  wd_base = NULL;
245  return ret;
246 }
247 
248 static int __devexit mpc8xxx_wdt_remove(struct platform_device *ofdev)
249 {
250  mpc8xxx_wdt_pr_warn("watchdog removed");
251  del_timer_sync(&wdt_timer);
252  misc_deregister(&mpc8xxx_wdt_miscdev);
253  iounmap(wd_base);
254 
255  return 0;
256 }
257 
258 static const struct of_device_id mpc8xxx_wdt_match[] = {
259  {
260  .compatible = "mpc83xx_wdt",
261  .data = &(struct mpc8xxx_wdt_type) {
262  .prescaler = 0x10000,
263  },
264  },
265  {
266  .compatible = "fsl,mpc8610-wdt",
267  .data = &(struct mpc8xxx_wdt_type) {
268  .prescaler = 0x10000,
269  .hw_enabled = true,
270  },
271  },
272  {
273  .compatible = "fsl,mpc823-wdt",
274  .data = &(struct mpc8xxx_wdt_type) {
275  .prescaler = 0x800,
276  },
277  },
278  {},
279 };
280 MODULE_DEVICE_TABLE(of, mpc8xxx_wdt_match);
281 
282 static struct platform_driver mpc8xxx_wdt_driver = {
283  .probe = mpc8xxx_wdt_probe,
284  .remove = __devexit_p(mpc8xxx_wdt_remove),
285  .driver = {
286  .name = "mpc8xxx_wdt",
287  .owner = THIS_MODULE,
288  .of_match_table = mpc8xxx_wdt_match,
289  },
290 };
291 
292 /*
293  * We do wdt initialization in two steps: arch_initcall probes the wdt
294  * very early to start pinging the watchdog (misc devices are not yet
295  * available), and later module_init() just registers the misc device.
296  */
297 static int mpc8xxx_wdt_init_late(void)
298 {
299  int ret;
300 
301  if (!wd_base)
302  return -ENODEV;
303 
304  ret = misc_register(&mpc8xxx_wdt_miscdev);
305  if (ret) {
306  pr_err("cannot register miscdev on minor=%d (err=%d)\n",
307  WATCHDOG_MINOR, ret);
308  return ret;
309  }
310  return 0;
311 }
312 #ifndef MODULE
313 module_init(mpc8xxx_wdt_init_late);
314 #endif
315 
316 static int __init mpc8xxx_wdt_init(void)
317 {
318  return platform_driver_register(&mpc8xxx_wdt_driver);
319 }
320 arch_initcall(mpc8xxx_wdt_init);
321 
322 static void __exit mpc8xxx_wdt_exit(void)
323 {
324  platform_driver_unregister(&mpc8xxx_wdt_driver);
325 }
326 module_exit(mpc8xxx_wdt_exit);
327 
328 MODULE_AUTHOR("Dave Updegraff, Kumar Gala");
329 MODULE_DESCRIPTION("Driver for watchdog timer in MPC8xx/MPC83xx/MPC86xx "
330  "uProcessors");
331 MODULE_LICENSE("GPL");