1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * Watchdog for the 7101 PMU version found in the ALi M1535 chipsets
4 */
5
6 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
7
8 #include <linux/module.h>
9 #include <linux/moduleparam.h>
10 #include <linux/types.h>
11 #include <linux/miscdevice.h>
12 #include <linux/watchdog.h>
13 #include <linux/ioport.h>
14 #include <linux/notifier.h>
15 #include <linux/reboot.h>
16 #include <linux/init.h>
17 #include <linux/fs.h>
18 #include <linux/pci.h>
19 #include <linux/uaccess.h>
20 #include <linux/io.h>
21
22 #define WATCHDOG_NAME "ALi_M1535"
23 #define WATCHDOG_TIMEOUT 60 /* 60 sec default timeout */
24
25 /* internal variables */
26 static unsigned long ali_is_open;
27 static char ali_expect_release;
28 static struct pci_dev *ali_pci;
29 static u32 ali_timeout_bits; /* stores the computed timeout */
30 static DEFINE_SPINLOCK(ali_lock); /* Guards the hardware */
31
32 /* module parameters */
33 static int timeout = WATCHDOG_TIMEOUT;
34 module_param(timeout, int, 0);
35 MODULE_PARM_DESC(timeout,
36 "Watchdog timeout in seconds. (0 < timeout < 18000, default="
37 __MODULE_STRING(WATCHDOG_TIMEOUT) ")");
38
39 static bool nowayout = WATCHDOG_NOWAYOUT;
40 module_param(nowayout, bool, 0);
41 MODULE_PARM_DESC(nowayout,
42 "Watchdog cannot be stopped once started (default="
43 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
44
45 /*
46 * ali_start - start watchdog countdown
47 *
48 * Starts the timer running providing the timer has a counter
49 * configuration set.
50 */
51
ali_start(void)52 static void ali_start(void)
53 {
54 u32 val;
55
56 spin_lock(&ali_lock);
57
58 pci_read_config_dword(ali_pci, 0xCC, &val);
59 val &= ~0x3F; /* Mask count */
60 val |= (1 << 25) | ali_timeout_bits;
61 pci_write_config_dword(ali_pci, 0xCC, val);
62
63 spin_unlock(&ali_lock);
64 }
65
66 /*
67 * ali_stop - stop the timer countdown
68 *
69 * Stop the ALi watchdog countdown
70 */
71
ali_stop(void)72 static void ali_stop(void)
73 {
74 u32 val;
75
76 spin_lock(&ali_lock);
77
78 pci_read_config_dword(ali_pci, 0xCC, &val);
79 val &= ~0x3F; /* Mask count to zero (disabled) */
80 val &= ~(1 << 25); /* and for safety mask the reset enable */
81 pci_write_config_dword(ali_pci, 0xCC, val);
82
83 spin_unlock(&ali_lock);
84 }
85
86 /*
87 * ali_keepalive - send a keepalive to the watchdog
88 *
89 * Send a keepalive to the timer (actually we restart the timer).
90 */
91
ali_keepalive(void)92 static void ali_keepalive(void)
93 {
94 ali_start();
95 }
96
97 /*
98 * ali_settimer - compute the timer reload value
99 * @t: time in seconds
100 *
101 * Computes the timeout values needed
102 */
103
ali_settimer(int t)104 static int ali_settimer(int t)
105 {
106 if (t < 0)
107 return -EINVAL;
108 else if (t < 60)
109 ali_timeout_bits = t|(1 << 6);
110 else if (t < 3600)
111 ali_timeout_bits = (t / 60)|(1 << 7);
112 else if (t < 18000)
113 ali_timeout_bits = (t / 300)|(1 << 6)|(1 << 7);
114 else
115 return -EINVAL;
116
117 timeout = t;
118 return 0;
119 }
120
121 /*
122 * /dev/watchdog handling
123 */
124
125 /*
126 * ali_write - writes to ALi watchdog
127 * @file: file from VFS
128 * @data: user address of data
129 * @len: length of data
130 * @ppos: pointer to the file offset
131 *
132 * Handle a write to the ALi watchdog. Writing to the file pings
133 * the watchdog and resets it. Writing the magic 'V' sequence allows
134 * the next close to turn off the watchdog.
135 */
136
ali_write(struct file * file,const char __user * data,size_t len,loff_t * ppos)137 static ssize_t ali_write(struct file *file, const char __user *data,
138 size_t len, loff_t *ppos)
139 {
140 /* See if we got the magic character 'V' and reload the timer */
141 if (len) {
142 if (!nowayout) {
143 size_t i;
144
145 /* note: just in case someone wrote the
146 magic character five months ago... */
147 ali_expect_release = 0;
148
149 /* scan to see whether or not we got
150 the magic character */
151 for (i = 0; i != len; i++) {
152 char c;
153 if (get_user(c, data + i))
154 return -EFAULT;
155 if (c == 'V')
156 ali_expect_release = 42;
157 }
158 }
159
160 /* someone wrote to us, we should reload the timer */
161 ali_start();
162 }
163 return len;
164 }
165
166 /*
167 * ali_ioctl - handle watchdog ioctls
168 * @file: VFS file pointer
169 * @cmd: ioctl number
170 * @arg: arguments to the ioctl
171 *
172 * Handle the watchdog ioctls supported by the ALi driver. Really
173 * we want an extension to enable irq ack monitoring and the like
174 */
175
ali_ioctl(struct file * file,unsigned int cmd,unsigned long arg)176 static long ali_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
177 {
178 void __user *argp = (void __user *)arg;
179 int __user *p = argp;
180 static const struct watchdog_info ident = {
181 .options = WDIOF_KEEPALIVEPING |
182 WDIOF_SETTIMEOUT |
183 WDIOF_MAGICCLOSE,
184 .firmware_version = 0,
185 .identity = "ALi M1535 WatchDog Timer",
186 };
187
188 switch (cmd) {
189 case WDIOC_GETSUPPORT:
190 return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
191
192 case WDIOC_GETSTATUS:
193 case WDIOC_GETBOOTSTATUS:
194 return put_user(0, p);
195 case WDIOC_SETOPTIONS:
196 {
197 int new_options, retval = -EINVAL;
198
199 if (get_user(new_options, p))
200 return -EFAULT;
201 if (new_options & WDIOS_DISABLECARD) {
202 ali_stop();
203 retval = 0;
204 }
205 if (new_options & WDIOS_ENABLECARD) {
206 ali_start();
207 retval = 0;
208 }
209 return retval;
210 }
211 case WDIOC_KEEPALIVE:
212 ali_keepalive();
213 return 0;
214 case WDIOC_SETTIMEOUT:
215 {
216 int new_timeout;
217 if (get_user(new_timeout, p))
218 return -EFAULT;
219 if (ali_settimer(new_timeout))
220 return -EINVAL;
221 ali_keepalive();
222 }
223 fallthrough;
224 case WDIOC_GETTIMEOUT:
225 return put_user(timeout, p);
226 default:
227 return -ENOTTY;
228 }
229 }
230
231 /*
232 * ali_open - handle open of ali watchdog
233 * @inode: inode from VFS
234 * @file: file from VFS
235 *
236 * Open the ALi watchdog device. Ensure only one person opens it
237 * at a time. Also start the watchdog running.
238 */
239
ali_open(struct inode * inode,struct file * file)240 static int ali_open(struct inode *inode, struct file *file)
241 {
242 /* /dev/watchdog can only be opened once */
243 if (test_and_set_bit(0, &ali_is_open))
244 return -EBUSY;
245
246 /* Activate */
247 ali_start();
248 return stream_open(inode, file);
249 }
250
251 /*
252 * ali_release - close an ALi watchdog
253 * @inode: inode from VFS
254 * @file: file from VFS
255 *
256 * Close the ALi watchdog device. Actual shutdown of the timer
257 * only occurs if the magic sequence has been set.
258 */
259
ali_release(struct inode * inode,struct file * file)260 static int ali_release(struct inode *inode, struct file *file)
261 {
262 /*
263 * Shut off the timer.
264 */
265 if (ali_expect_release == 42)
266 ali_stop();
267 else {
268 pr_crit("Unexpected close, not stopping watchdog!\n");
269 ali_keepalive();
270 }
271 clear_bit(0, &ali_is_open);
272 ali_expect_release = 0;
273 return 0;
274 }
275
276 /*
277 * ali_notify_sys - System down notifier
278 *
279 * Notifier for system down
280 */
281
282
ali_notify_sys(struct notifier_block * this,unsigned long code,void * unused)283 static int ali_notify_sys(struct notifier_block *this,
284 unsigned long code, void *unused)
285 {
286 if (code == SYS_DOWN || code == SYS_HALT)
287 ali_stop(); /* Turn the WDT off */
288 return NOTIFY_DONE;
289 }
290
291 /*
292 * Data for PCI driver interface
293 *
294 * This data only exists for exporting the supported
295 * PCI ids via MODULE_DEVICE_TABLE. We do not actually
296 * register a pci_driver, because someone else might one day
297 * want to register another driver on the same PCI id.
298 */
299
300 static const struct pci_device_id ali_pci_tbl[] __used = {
301 { PCI_VENDOR_ID_AL, 0x1533, PCI_ANY_ID, PCI_ANY_ID,},
302 { PCI_VENDOR_ID_AL, 0x1535, PCI_ANY_ID, PCI_ANY_ID,},
303 { 0, },
304 };
305 MODULE_DEVICE_TABLE(pci, ali_pci_tbl);
306
307 /*
308 * ali_find_watchdog - find a 1535 and 7101
309 *
310 * Scans the PCI hardware for a 1535 series bridge and matching 7101
311 * watchdog device. This may be overtight but it is better to be safe
312 */
313
ali_find_watchdog(void)314 static int __init ali_find_watchdog(void)
315 {
316 struct pci_dev *pdev;
317 u32 wdog;
318
319 /* Check for a 1533/1535 series bridge */
320 pdev = pci_get_device(PCI_VENDOR_ID_AL, 0x1535, NULL);
321 if (pdev == NULL)
322 pdev = pci_get_device(PCI_VENDOR_ID_AL, 0x1533, NULL);
323 if (pdev == NULL)
324 return -ENODEV;
325 pci_dev_put(pdev);
326
327 /* Check for the a 7101 PMU */
328 pdev = pci_get_device(PCI_VENDOR_ID_AL, 0x7101, NULL);
329 if (pdev == NULL)
330 return -ENODEV;
331
332 if (pci_enable_device(pdev)) {
333 pci_dev_put(pdev);
334 return -EIO;
335 }
336
337 ali_pci = pdev;
338
339 /*
340 * Initialize the timer bits
341 */
342 pci_read_config_dword(pdev, 0xCC, &wdog);
343
344 /* Timer bits */
345 wdog &= ~0x3F;
346 /* Issued events */
347 wdog &= ~((1 << 27)|(1 << 26)|(1 << 25)|(1 << 24));
348 /* No monitor bits */
349 wdog &= ~((1 << 16)|(1 << 13)|(1 << 12)|(1 << 11)|(1 << 10)|(1 << 9));
350
351 pci_write_config_dword(pdev, 0xCC, wdog);
352
353 return 0;
354 }
355
356 /*
357 * Kernel Interfaces
358 */
359
360 static const struct file_operations ali_fops = {
361 .owner = THIS_MODULE,
362 .llseek = no_llseek,
363 .write = ali_write,
364 .unlocked_ioctl = ali_ioctl,
365 .compat_ioctl = compat_ptr_ioctl,
366 .open = ali_open,
367 .release = ali_release,
368 };
369
370 static struct miscdevice ali_miscdev = {
371 .minor = WATCHDOG_MINOR,
372 .name = "watchdog",
373 .fops = &ali_fops,
374 };
375
376 static struct notifier_block ali_notifier = {
377 .notifier_call = ali_notify_sys,
378 };
379
380 /*
381 * watchdog_init - module initialiser
382 *
383 * Scan for a suitable watchdog and if so initialize it. Return an error
384 * if we cannot, the error causes the module to unload
385 */
386
watchdog_init(void)387 static int __init watchdog_init(void)
388 {
389 int ret;
390
391 /* Check whether or not the hardware watchdog is there */
392 if (ali_find_watchdog() != 0)
393 return -ENODEV;
394
395 /* Check that the timeout value is within it's range;
396 if not reset to the default */
397 if (timeout < 1 || timeout >= 18000) {
398 timeout = WATCHDOG_TIMEOUT;
399 pr_info("timeout value must be 0 < timeout < 18000, using %d\n",
400 timeout);
401 }
402
403 /* Calculate the watchdog's timeout */
404 ali_settimer(timeout);
405
406 ret = register_reboot_notifier(&ali_notifier);
407 if (ret != 0) {
408 pr_err("cannot register reboot notifier (err=%d)\n", ret);
409 goto out;
410 }
411
412 ret = misc_register(&ali_miscdev);
413 if (ret != 0) {
414 pr_err("cannot register miscdev on minor=%d (err=%d)\n",
415 WATCHDOG_MINOR, ret);
416 goto unreg_reboot;
417 }
418
419 pr_info("initialized. timeout=%d sec (nowayout=%d)\n",
420 timeout, nowayout);
421
422 out:
423 return ret;
424 unreg_reboot:
425 unregister_reboot_notifier(&ali_notifier);
426 goto out;
427 }
428
429 /*
430 * watchdog_exit - module de-initialiser
431 *
432 * Called while unloading a successfully installed watchdog module.
433 */
434
watchdog_exit(void)435 static void __exit watchdog_exit(void)
436 {
437 /* Stop the timer before we leave */
438 ali_stop();
439
440 /* Deregister */
441 misc_deregister(&ali_miscdev);
442 unregister_reboot_notifier(&ali_notifier);
443 pci_dev_put(ali_pci);
444 }
445
446 module_init(watchdog_init);
447 module_exit(watchdog_exit);
448
449 MODULE_AUTHOR("Alan Cox");
450 MODULE_DESCRIPTION("ALi M1535 PMU Watchdog Timer driver");
451 MODULE_LICENSE("GPL");
452