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1/*
2 * AMD Elan SC520 processor Watchdog Timer driver
3 *
4 * Based on acquirewdt.c by Alan Cox,
5 * and sbc60xxwdt.c by Jakob Oestergaard <jakob@unthought.net>
6 *
7 * This program is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU General Public License
9 * as published by the Free Software Foundation; either version
10 * 2 of the License, or (at your option) any later version.
11 *
12 * The authors do NOT admit liability nor provide warranty for
13 * any of this software. This material is provided "AS-IS" in
14 * the hope that it may be useful for others.
15 *
16 * (c) Copyright 2001 Scott Jennings <linuxdrivers@oro.net>
17 * 9/27 - 2001 [Initial release]
18 *
19 * Additional fixes Alan Cox
20 * - Fixed formatting
21 * - Removed debug printks
22 * - Fixed SMP built kernel deadlock
23 * - Switched to private locks not lock_kernel
24 * - Used ioremap/writew/readw
25 * - Added NOWAYOUT support
26 * 4/12 - 2002 Changes by Rob Radez <rob@osinvestor.com>
27 * - Change comments
28 * - Eliminate fop_llseek
29 * - Change CONFIG_WATCHDOG_NOWAYOUT semantics
30 * - Add KERN_* tags to printks
31 * - fix possible wdt_is_open race
32 * - Report proper capabilities in watchdog_info
33 * - Add WDIOC_{GETSTATUS, GETBOOTSTATUS, SETTIMEOUT,
34 * GETTIMEOUT, SETOPTIONS} ioctls
35 * 09/8 - 2003 Changes by Wim Van Sebroeck <wim@iguana.be>
36 * - cleanup of trailing spaces
37 * - added extra printk's for startup problems
38 * - use module_param
39 * - made timeout (the emulated heartbeat) a module_param
40 * - made the keepalive ping an internal subroutine
41 * 3/27 - 2004 Changes by Sean Young <sean@mess.org>
42 * - set MMCR_BASE to 0xfffef000
43 * - CBAR does not need to be read
44 * - removed debugging printks
45 *
46 * This WDT driver is different from most other Linux WDT
47 * drivers in that the driver will ping the watchdog by itself,
48 * because this particular WDT has a very short timeout (1.6
49 * seconds) and it would be insane to count on any userspace
50 * daemon always getting scheduled within that time frame.
51 *
52 * This driver uses memory mapped IO, and spinlock.
53 */
54
55#include <linux/module.h>
56#include <linux/moduleparam.h>
57#include <linux/types.h>
58#include <linux/timer.h>
59#include <linux/miscdevice.h>
60#include <linux/watchdog.h>
61#include <linux/fs.h>
62#include <linux/ioport.h>
63#include <linux/notifier.h>
64#include <linux/reboot.h>
65#include <linux/init.h>
66#include <linux/jiffies.h>
67#include <linux/io.h>
68#include <linux/uaccess.h>
69
70#include <asm/system.h>
71
72#define OUR_NAME "sc520_wdt"
73#define PFX OUR_NAME ": "
74
75/*
76 * The AMD Elan SC520 timeout value is 492us times a power of 2 (0-7)
77 *
78 * 0: 492us 2: 1.01s 4: 4.03s 6: 16.22s
79 * 1: 503ms 3: 2.01s 5: 8.05s 7: 32.21s
80 *
81 * We will program the SC520 watchdog for a timeout of 2.01s.
82 * If we reset the watchdog every ~250ms we should be safe.
83 */
84
85#define WDT_INTERVAL (HZ/4+1)
86
87/*
88 * We must not require too good response from the userspace daemon.
89 * Here we require the userspace daemon to send us a heartbeat
90 * char to /dev/watchdog every 30 seconds.
91 */
92
93#define WATCHDOG_TIMEOUT 30 /* 30 sec default timeout */
94/* in seconds, will be multiplied by HZ to get seconds to wait for a ping */
95static int timeout = WATCHDOG_TIMEOUT;
96module_param(timeout, int, 0);
97MODULE_PARM_DESC(timeout,
98 "Watchdog timeout in seconds. (1 <= timeout <= 3600, default="
99 __MODULE_STRING(WATCHDOG_TIMEOUT) ")");
100
101static int nowayout = WATCHDOG_NOWAYOUT;
102module_param(nowayout, int, 0);
103MODULE_PARM_DESC(nowayout,
104 "Watchdog cannot be stopped once started (default="
105 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
106
107/*
108 * AMD Elan SC520 - Watchdog Timer Registers
109 */
110#define MMCR_BASE 0xfffef000 /* The default base address */
111#define OFFS_WDTMRCTL 0xCB0 /* Watchdog Timer Control Register */
112
113/* WDT Control Register bit definitions */
114#define WDT_EXP_SEL_01 0x0001 /* [01] Time-out = 496 us (with 33 Mhz clk). */
115#define WDT_EXP_SEL_02 0x0002 /* [02] Time-out = 508 ms (with 33 Mhz clk). */
116#define WDT_EXP_SEL_03 0x0004 /* [03] Time-out = 1.02 s (with 33 Mhz clk). */
117#define WDT_EXP_SEL_04 0x0008 /* [04] Time-out = 2.03 s (with 33 Mhz clk). */
118#define WDT_EXP_SEL_05 0x0010 /* [05] Time-out = 4.07 s (with 33 Mhz clk). */
119#define WDT_EXP_SEL_06 0x0020 /* [06] Time-out = 8.13 s (with 33 Mhz clk). */
120#define WDT_EXP_SEL_07 0x0040 /* [07] Time-out = 16.27s (with 33 Mhz clk). */
121#define WDT_EXP_SEL_08 0x0080 /* [08] Time-out = 32.54s (with 33 Mhz clk). */
122#define WDT_IRQ_FLG 0x1000 /* [12] Interrupt Request Flag */
123#define WDT_WRST_ENB 0x4000 /* [14] Watchdog Timer Reset Enable */
124#define WDT_ENB 0x8000 /* [15] Watchdog Timer Enable */
125
126static __u16 __iomem *wdtmrctl;
127
128static void wdt_timer_ping(unsigned long);
129static DEFINE_TIMER(timer, wdt_timer_ping, 0, 0);
130static unsigned long next_heartbeat;
131static unsigned long wdt_is_open;
132static char wdt_expect_close;
133static DEFINE_SPINLOCK(wdt_spinlock);
134
135/*
136 * Whack the dog
137 */
138
139static void wdt_timer_ping(unsigned long data)
140{
141 /* If we got a heartbeat pulse within the WDT_US_INTERVAL
142 * we agree to ping the WDT
143 */
144 if (time_before(jiffies, next_heartbeat)) {
145 /* Ping the WDT */
146 spin_lock(&wdt_spinlock);
147 writew(0xAAAA, wdtmrctl);
148 writew(0x5555, wdtmrctl);
149 spin_unlock(&wdt_spinlock);
150
151 /* Re-set the timer interval */
152 mod_timer(&timer, jiffies + WDT_INTERVAL);
153 } else
154 printk(KERN_WARNING PFX
155 "Heartbeat lost! Will not ping the watchdog\n");
156}
157
158/*
159 * Utility routines
160 */
161
162static void wdt_config(int writeval)
163{
164 __u16 dummy;
165 unsigned long flags;
166
167 /* buy some time (ping) */
168 spin_lock_irqsave(&wdt_spinlock, flags);
169 dummy = readw(wdtmrctl); /* ensure write synchronization */
170 writew(0xAAAA, wdtmrctl);
171 writew(0x5555, wdtmrctl);
172 /* unlock WDT = make WDT configuration register writable one time */
173 writew(0x3333, wdtmrctl);
174 writew(0xCCCC, wdtmrctl);
175 /* write WDT configuration register */
176 writew(writeval, wdtmrctl);
177 spin_unlock_irqrestore(&wdt_spinlock, flags);
178}
179
180static int wdt_startup(void)
181{
182 next_heartbeat = jiffies + (timeout * HZ);
183
184 /* Start the timer */
185 mod_timer(&timer, jiffies + WDT_INTERVAL);
186
187 /* Start the watchdog */
188 wdt_config(WDT_ENB | WDT_WRST_ENB | WDT_EXP_SEL_04);
189
190 printk(KERN_INFO PFX "Watchdog timer is now enabled.\n");
191 return 0;
192}
193
194static int wdt_turnoff(void)
195{
196 /* Stop the timer */
197 del_timer(&timer);
198
199 /* Stop the watchdog */
200 wdt_config(0);
201
202 printk(KERN_INFO PFX "Watchdog timer is now disabled...\n");
203 return 0;
204}
205
206static int wdt_keepalive(void)
207{
208 /* user land ping */
209 next_heartbeat = jiffies + (timeout * HZ);
210 return 0;
211}
212
213static int wdt_set_heartbeat(int t)
214{
215 if ((t < 1) || (t > 3600)) /* arbitrary upper limit */
216 return -EINVAL;
217
218 timeout = t;
219 return 0;
220}
221
222/*
223 * /dev/watchdog handling
224 */
225
226static ssize_t fop_write(struct file *file, const char __user *buf,
227 size_t count, loff_t *ppos)
228{
229 /* See if we got the magic character 'V' and reload the timer */
230 if (count) {
231 if (!nowayout) {
232 size_t ofs;
233
234 /* note: just in case someone wrote the magic character
235 * five months ago... */
236 wdt_expect_close = 0;
237
238 /* now scan */
239 for (ofs = 0; ofs != count; ofs++) {
240 char c;
241 if (get_user(c, buf + ofs))
242 return -EFAULT;
243 if (c == 'V')
244 wdt_expect_close = 42;
245 }
246 }
247
248 /* Well, anyhow someone wrote to us, we should
249 return that favour */
250 wdt_keepalive();
251 }
252 return count;
253}
254
255static int fop_open(struct inode *inode, struct file *file)
256{
257 /* Just in case we're already talking to someone... */
258 if (test_and_set_bit(0, &wdt_is_open))
259 return -EBUSY;
260 if (nowayout)
261 __module_get(THIS_MODULE);
262
263 /* Good, fire up the show */
264 wdt_startup();
265 return nonseekable_open(inode, file);
266}
267
268static int fop_close(struct inode *inode, struct file *file)
269{
270 if (wdt_expect_close == 42)
271 wdt_turnoff();
272 else {
273 printk(KERN_CRIT PFX
274 "Unexpected close, not stopping watchdog!\n");
275 wdt_keepalive();
276 }
277 clear_bit(0, &wdt_is_open);
278 wdt_expect_close = 0;
279 return 0;
280}
281
282static long fop_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
283{
284 void __user *argp = (void __user *)arg;
285 int __user *p = argp;
286 static const struct watchdog_info ident = {
287 .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT
288 | WDIOF_MAGICCLOSE,
289 .firmware_version = 1,
290 .identity = "SC520",
291 };
292
293 switch (cmd) {
294 case WDIOC_GETSUPPORT:
295 return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
296 case WDIOC_GETSTATUS:
297 case WDIOC_GETBOOTSTATUS:
298 return put_user(0, p);
299 case WDIOC_SETOPTIONS:
300 {
301 int new_options, retval = -EINVAL;
302
303 if (get_user(new_options, p))
304 return -EFAULT;
305
306 if (new_options & WDIOS_DISABLECARD) {
307 wdt_turnoff();
308 retval = 0;
309 }
310
311 if (new_options & WDIOS_ENABLECARD) {
312 wdt_startup();
313 retval = 0;
314 }
315
316 return retval;
317 }
318 case WDIOC_KEEPALIVE:
319 wdt_keepalive();
320 return 0;
321 case WDIOC_SETTIMEOUT:
322 {
323 int new_timeout;
324
325 if (get_user(new_timeout, p))
326 return -EFAULT;
327
328 if (wdt_set_heartbeat(new_timeout))
329 return -EINVAL;
330
331 wdt_keepalive();
332 /* Fall through */
333 }
334 case WDIOC_GETTIMEOUT:
335 return put_user(timeout, p);
336 default:
337 return -ENOTTY;
338 }
339}
340
341static const struct file_operations wdt_fops = {
342 .owner = THIS_MODULE,
343 .llseek = no_llseek,
344 .write = fop_write,
345 .open = fop_open,
346 .release = fop_close,
347 .unlocked_ioctl = fop_ioctl,
348};
349
350static struct miscdevice wdt_miscdev = {
351 .minor = WATCHDOG_MINOR,
352 .name = "watchdog",
353 .fops = &wdt_fops,
354};
355
356/*
357 * Notifier for system down
358 */
359
360static int wdt_notify_sys(struct notifier_block *this, unsigned long code,
361 void *unused)
362{
363 if (code == SYS_DOWN || code == SYS_HALT)
364 wdt_turnoff();
365 return NOTIFY_DONE;
366}
367
368/*
369 * The WDT needs to learn about soft shutdowns in order to
370 * turn the timebomb registers off.
371 */
372
373static struct notifier_block wdt_notifier = {
374 .notifier_call = wdt_notify_sys,
375};
376
377static void __exit sc520_wdt_unload(void)
378{
379 if (!nowayout)
380 wdt_turnoff();
381
382 /* Deregister */
383 misc_deregister(&wdt_miscdev);
384 unregister_reboot_notifier(&wdt_notifier);
385 iounmap(wdtmrctl);
386}
387
388static int __init sc520_wdt_init(void)
389{
390 int rc = -EBUSY;
391
392 /* Check that the timeout value is within it's range ;
393 if not reset to the default */
394 if (wdt_set_heartbeat(timeout)) {
395 wdt_set_heartbeat(WATCHDOG_TIMEOUT);
396 printk(KERN_INFO PFX
397 "timeout value must be 1 <= timeout <= 3600, using %d\n",
398 WATCHDOG_TIMEOUT);
399 }
400
401 wdtmrctl = ioremap((unsigned long)(MMCR_BASE + OFFS_WDTMRCTL), 2);
402 if (!wdtmrctl) {
403 printk(KERN_ERR PFX "Unable to remap memory\n");
404 rc = -ENOMEM;
405 goto err_out_region2;
406 }
407
408 rc = register_reboot_notifier(&wdt_notifier);
409 if (rc) {
410 printk(KERN_ERR PFX
411 "cannot register reboot notifier (err=%d)\n", rc);
412 goto err_out_ioremap;
413 }
414
415 rc = misc_register(&wdt_miscdev);
416 if (rc) {
417 printk(KERN_ERR PFX
418 "cannot register miscdev on minor=%d (err=%d)\n",
419 WATCHDOG_MINOR, rc);
420 goto err_out_notifier;
421 }
422
423 printk(KERN_INFO PFX
424 "WDT driver for SC520 initialised. timeout=%d sec (nowayout=%d)\n",
425 timeout, nowayout);
426
427 return 0;
428
429err_out_notifier:
430 unregister_reboot_notifier(&wdt_notifier);
431err_out_ioremap:
432 iounmap(wdtmrctl);
433err_out_region2:
434 return rc;
435}
436
437module_init(sc520_wdt_init);
438module_exit(sc520_wdt_unload);
439
440MODULE_AUTHOR("Scott and Bill Jennings");
441MODULE_DESCRIPTION(
442 "Driver for watchdog timer in AMD \"Elan\" SC520 uProcessor");
443MODULE_LICENSE("GPL");
444MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * AMD Elan SC520 processor Watchdog Timer driver
4 *
5 * Based on acquirewdt.c by Alan Cox,
6 * and sbc60xxwdt.c by Jakob Oestergaard <jakob@unthought.net>
7 *
8 * The authors do NOT admit liability nor provide warranty for
9 * any of this software. This material is provided "AS-IS" in
10 * the hope that it may be useful for others.
11 *
12 * (c) Copyright 2001 Scott Jennings <linuxdrivers@oro.net>
13 * 9/27 - 2001 [Initial release]
14 *
15 * Additional fixes Alan Cox
16 * - Fixed formatting
17 * - Removed debug printks
18 * - Fixed SMP built kernel deadlock
19 * - Switched to private locks not lock_kernel
20 * - Used ioremap/writew/readw
21 * - Added NOWAYOUT support
22 * 4/12 - 2002 Changes by Rob Radez <rob@osinvestor.com>
23 * - Change comments
24 * - Eliminate fop_llseek
25 * - Change CONFIG_WATCHDOG_NOWAYOUT semantics
26 * - Add KERN_* tags to printks
27 * - fix possible wdt_is_open race
28 * - Report proper capabilities in watchdog_info
29 * - Add WDIOC_{GETSTATUS, GETBOOTSTATUS, SETTIMEOUT,
30 * GETTIMEOUT, SETOPTIONS} ioctls
31 * 09/8 - 2003 Changes by Wim Van Sebroeck <wim@iguana.be>
32 * - cleanup of trailing spaces
33 * - added extra printk's for startup problems
34 * - use module_param
35 * - made timeout (the emulated heartbeat) a module_param
36 * - made the keepalive ping an internal subroutine
37 * 3/27 - 2004 Changes by Sean Young <sean@mess.org>
38 * - set MMCR_BASE to 0xfffef000
39 * - CBAR does not need to be read
40 * - removed debugging printks
41 *
42 * This WDT driver is different from most other Linux WDT
43 * drivers in that the driver will ping the watchdog by itself,
44 * because this particular WDT has a very short timeout (1.6
45 * seconds) and it would be insane to count on any userspace
46 * daemon always getting scheduled within that time frame.
47 *
48 * This driver uses memory mapped IO, and spinlock.
49 */
50
51#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
52
53#include <linux/module.h>
54#include <linux/moduleparam.h>
55#include <linux/types.h>
56#include <linux/timer.h>
57#include <linux/miscdevice.h>
58#include <linux/watchdog.h>
59#include <linux/fs.h>
60#include <linux/ioport.h>
61#include <linux/notifier.h>
62#include <linux/reboot.h>
63#include <linux/init.h>
64#include <linux/jiffies.h>
65#include <linux/io.h>
66#include <linux/uaccess.h>
67
68
69/*
70 * The AMD Elan SC520 timeout value is 492us times a power of 2 (0-7)
71 *
72 * 0: 492us 2: 1.01s 4: 4.03s 6: 16.22s
73 * 1: 503ms 3: 2.01s 5: 8.05s 7: 32.21s
74 *
75 * We will program the SC520 watchdog for a timeout of 2.01s.
76 * If we reset the watchdog every ~250ms we should be safe.
77 */
78
79#define WDT_INTERVAL (HZ/4+1)
80
81/*
82 * We must not require too good response from the userspace daemon.
83 * Here we require the userspace daemon to send us a heartbeat
84 * char to /dev/watchdog every 30 seconds.
85 */
86
87#define WATCHDOG_TIMEOUT 30 /* 30 sec default timeout */
88/* in seconds, will be multiplied by HZ to get seconds to wait for a ping */
89static int timeout = WATCHDOG_TIMEOUT;
90module_param(timeout, int, 0);
91MODULE_PARM_DESC(timeout,
92 "Watchdog timeout in seconds. (1 <= timeout <= 3600, default="
93 __MODULE_STRING(WATCHDOG_TIMEOUT) ")");
94
95static bool nowayout = WATCHDOG_NOWAYOUT;
96module_param(nowayout, bool, 0);
97MODULE_PARM_DESC(nowayout,
98 "Watchdog cannot be stopped once started (default="
99 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
100
101/*
102 * AMD Elan SC520 - Watchdog Timer Registers
103 */
104#define MMCR_BASE 0xfffef000 /* The default base address */
105#define OFFS_WDTMRCTL 0xCB0 /* Watchdog Timer Control Register */
106
107/* WDT Control Register bit definitions */
108#define WDT_EXP_SEL_01 0x0001 /* [01] Time-out = 496 us (with 33 Mhz clk). */
109#define WDT_EXP_SEL_02 0x0002 /* [02] Time-out = 508 ms (with 33 Mhz clk). */
110#define WDT_EXP_SEL_03 0x0004 /* [03] Time-out = 1.02 s (with 33 Mhz clk). */
111#define WDT_EXP_SEL_04 0x0008 /* [04] Time-out = 2.03 s (with 33 Mhz clk). */
112#define WDT_EXP_SEL_05 0x0010 /* [05] Time-out = 4.07 s (with 33 Mhz clk). */
113#define WDT_EXP_SEL_06 0x0020 /* [06] Time-out = 8.13 s (with 33 Mhz clk). */
114#define WDT_EXP_SEL_07 0x0040 /* [07] Time-out = 16.27s (with 33 Mhz clk). */
115#define WDT_EXP_SEL_08 0x0080 /* [08] Time-out = 32.54s (with 33 Mhz clk). */
116#define WDT_IRQ_FLG 0x1000 /* [12] Interrupt Request Flag */
117#define WDT_WRST_ENB 0x4000 /* [14] Watchdog Timer Reset Enable */
118#define WDT_ENB 0x8000 /* [15] Watchdog Timer Enable */
119
120static __u16 __iomem *wdtmrctl;
121
122static void wdt_timer_ping(struct timer_list *);
123static DEFINE_TIMER(timer, wdt_timer_ping);
124static unsigned long next_heartbeat;
125static unsigned long wdt_is_open;
126static char wdt_expect_close;
127static DEFINE_SPINLOCK(wdt_spinlock);
128
129/*
130 * Whack the dog
131 */
132
133static void wdt_timer_ping(struct timer_list *unused)
134{
135 /* If we got a heartbeat pulse within the WDT_US_INTERVAL
136 * we agree to ping the WDT
137 */
138 if (time_before(jiffies, next_heartbeat)) {
139 /* Ping the WDT */
140 spin_lock(&wdt_spinlock);
141 writew(0xAAAA, wdtmrctl);
142 writew(0x5555, wdtmrctl);
143 spin_unlock(&wdt_spinlock);
144
145 /* Re-set the timer interval */
146 mod_timer(&timer, jiffies + WDT_INTERVAL);
147 } else
148 pr_warn("Heartbeat lost! Will not ping the watchdog\n");
149}
150
151/*
152 * Utility routines
153 */
154
155static void wdt_config(int writeval)
156{
157 unsigned long flags;
158
159 /* buy some time (ping) */
160 spin_lock_irqsave(&wdt_spinlock, flags);
161 readw(wdtmrctl); /* ensure write synchronization */
162 writew(0xAAAA, wdtmrctl);
163 writew(0x5555, wdtmrctl);
164 /* unlock WDT = make WDT configuration register writable one time */
165 writew(0x3333, wdtmrctl);
166 writew(0xCCCC, wdtmrctl);
167 /* write WDT configuration register */
168 writew(writeval, wdtmrctl);
169 spin_unlock_irqrestore(&wdt_spinlock, flags);
170}
171
172static int wdt_startup(void)
173{
174 next_heartbeat = jiffies + (timeout * HZ);
175
176 /* Start the timer */
177 mod_timer(&timer, jiffies + WDT_INTERVAL);
178
179 /* Start the watchdog */
180 wdt_config(WDT_ENB | WDT_WRST_ENB | WDT_EXP_SEL_04);
181
182 pr_info("Watchdog timer is now enabled\n");
183 return 0;
184}
185
186static int wdt_turnoff(void)
187{
188 /* Stop the timer */
189 del_timer_sync(&timer);
190
191 /* Stop the watchdog */
192 wdt_config(0);
193
194 pr_info("Watchdog timer is now disabled...\n");
195 return 0;
196}
197
198static int wdt_keepalive(void)
199{
200 /* user land ping */
201 next_heartbeat = jiffies + (timeout * HZ);
202 return 0;
203}
204
205static int wdt_set_heartbeat(int t)
206{
207 if ((t < 1) || (t > 3600)) /* arbitrary upper limit */
208 return -EINVAL;
209
210 timeout = t;
211 return 0;
212}
213
214/*
215 * /dev/watchdog handling
216 */
217
218static ssize_t fop_write(struct file *file, const char __user *buf,
219 size_t count, loff_t *ppos)
220{
221 /* See if we got the magic character 'V' and reload the timer */
222 if (count) {
223 if (!nowayout) {
224 size_t ofs;
225
226 /* note: just in case someone wrote the magic character
227 * five months ago... */
228 wdt_expect_close = 0;
229
230 /* now scan */
231 for (ofs = 0; ofs != count; ofs++) {
232 char c;
233 if (get_user(c, buf + ofs))
234 return -EFAULT;
235 if (c == 'V')
236 wdt_expect_close = 42;
237 }
238 }
239
240 /* Well, anyhow someone wrote to us, we should
241 return that favour */
242 wdt_keepalive();
243 }
244 return count;
245}
246
247static int fop_open(struct inode *inode, struct file *file)
248{
249 /* Just in case we're already talking to someone... */
250 if (test_and_set_bit(0, &wdt_is_open))
251 return -EBUSY;
252 if (nowayout)
253 __module_get(THIS_MODULE);
254
255 /* Good, fire up the show */
256 wdt_startup();
257 return stream_open(inode, file);
258}
259
260static int fop_close(struct inode *inode, struct file *file)
261{
262 if (wdt_expect_close == 42)
263 wdt_turnoff();
264 else {
265 pr_crit("Unexpected close, not stopping watchdog!\n");
266 wdt_keepalive();
267 }
268 clear_bit(0, &wdt_is_open);
269 wdt_expect_close = 0;
270 return 0;
271}
272
273static long fop_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
274{
275 void __user *argp = (void __user *)arg;
276 int __user *p = argp;
277 static const struct watchdog_info ident = {
278 .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT
279 | WDIOF_MAGICCLOSE,
280 .firmware_version = 1,
281 .identity = "SC520",
282 };
283
284 switch (cmd) {
285 case WDIOC_GETSUPPORT:
286 return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
287 case WDIOC_GETSTATUS:
288 case WDIOC_GETBOOTSTATUS:
289 return put_user(0, p);
290 case WDIOC_SETOPTIONS:
291 {
292 int new_options, retval = -EINVAL;
293
294 if (get_user(new_options, p))
295 return -EFAULT;
296
297 if (new_options & WDIOS_DISABLECARD) {
298 wdt_turnoff();
299 retval = 0;
300 }
301
302 if (new_options & WDIOS_ENABLECARD) {
303 wdt_startup();
304 retval = 0;
305 }
306
307 return retval;
308 }
309 case WDIOC_KEEPALIVE:
310 wdt_keepalive();
311 return 0;
312 case WDIOC_SETTIMEOUT:
313 {
314 int new_timeout;
315
316 if (get_user(new_timeout, p))
317 return -EFAULT;
318
319 if (wdt_set_heartbeat(new_timeout))
320 return -EINVAL;
321
322 wdt_keepalive();
323 }
324 fallthrough;
325 case WDIOC_GETTIMEOUT:
326 return put_user(timeout, p);
327 default:
328 return -ENOTTY;
329 }
330}
331
332static const struct file_operations wdt_fops = {
333 .owner = THIS_MODULE,
334 .write = fop_write,
335 .open = fop_open,
336 .release = fop_close,
337 .unlocked_ioctl = fop_ioctl,
338 .compat_ioctl = compat_ptr_ioctl,
339};
340
341static struct miscdevice wdt_miscdev = {
342 .minor = WATCHDOG_MINOR,
343 .name = "watchdog",
344 .fops = &wdt_fops,
345};
346
347/*
348 * Notifier for system down
349 */
350
351static int wdt_notify_sys(struct notifier_block *this, unsigned long code,
352 void *unused)
353{
354 if (code == SYS_DOWN || code == SYS_HALT)
355 wdt_turnoff();
356 return NOTIFY_DONE;
357}
358
359/*
360 * The WDT needs to learn about soft shutdowns in order to
361 * turn the timebomb registers off.
362 */
363
364static struct notifier_block wdt_notifier = {
365 .notifier_call = wdt_notify_sys,
366};
367
368static void __exit sc520_wdt_unload(void)
369{
370 if (!nowayout)
371 wdt_turnoff();
372
373 /* Deregister */
374 misc_deregister(&wdt_miscdev);
375 unregister_reboot_notifier(&wdt_notifier);
376 iounmap(wdtmrctl);
377}
378
379static int __init sc520_wdt_init(void)
380{
381 int rc = -EBUSY;
382
383 /* Check that the timeout value is within it's range ;
384 if not reset to the default */
385 if (wdt_set_heartbeat(timeout)) {
386 wdt_set_heartbeat(WATCHDOG_TIMEOUT);
387 pr_info("timeout value must be 1 <= timeout <= 3600, using %d\n",
388 WATCHDOG_TIMEOUT);
389 }
390
391 wdtmrctl = ioremap(MMCR_BASE + OFFS_WDTMRCTL, 2);
392 if (!wdtmrctl) {
393 pr_err("Unable to remap memory\n");
394 rc = -ENOMEM;
395 goto err_out_region2;
396 }
397
398 rc = register_reboot_notifier(&wdt_notifier);
399 if (rc) {
400 pr_err("cannot register reboot notifier (err=%d)\n", rc);
401 goto err_out_ioremap;
402 }
403
404 rc = misc_register(&wdt_miscdev);
405 if (rc) {
406 pr_err("cannot register miscdev on minor=%d (err=%d)\n",
407 WATCHDOG_MINOR, rc);
408 goto err_out_notifier;
409 }
410
411 pr_info("WDT driver for SC520 initialised. timeout=%d sec (nowayout=%d)\n",
412 timeout, nowayout);
413
414 return 0;
415
416err_out_notifier:
417 unregister_reboot_notifier(&wdt_notifier);
418err_out_ioremap:
419 iounmap(wdtmrctl);
420err_out_region2:
421 return rc;
422}
423
424module_init(sc520_wdt_init);
425module_exit(sc520_wdt_unload);
426
427MODULE_AUTHOR("Scott and Bill Jennings");
428MODULE_DESCRIPTION(
429 "Driver for watchdog timer in AMD \"Elan\" SC520 uProcessor");
430MODULE_LICENSE("GPL");