1 /*
2 * coh901327_wdt.c
3 *
4 * Copyright (C) 2008-2009 ST-Ericsson AB
5 * License terms: GNU General Public License (GPL) version 2
6 * Watchdog driver for the ST-Ericsson AB COH 901 327 IP core
7 * Author: Linus Walleij <linus.walleij@stericsson.com>
8 */
9 #include <linux/module.h>
10 #include <linux/types.h>
11 #include <linux/fs.h>
12 #include <linux/miscdevice.h>
13 #include <linux/watchdog.h>
14 #include <linux/interrupt.h>
15 #include <linux/pm.h>
16 #include <linux/platform_device.h>
17 #include <linux/io.h>
18 #include <linux/bitops.h>
19 #include <linux/uaccess.h>
20 #include <linux/clk.h>
21 #include <linux/delay.h>
22
23 #define DRV_NAME "WDOG COH 901 327"
24
25 /*
26 * COH 901 327 register definitions
27 */
28
29 /* WDOG_FEED Register 32bit (-/W) */
30 #define U300_WDOG_FR 0x00
31 #define U300_WDOG_FR_FEED_RESTART_TIMER 0xFEEDU
32 /* WDOG_TIMEOUT Register 32bit (R/W) */
33 #define U300_WDOG_TR 0x04
34 #define U300_WDOG_TR_TIMEOUT_MASK 0x7FFFU
35 /* WDOG_DISABLE1 Register 32bit (-/W) */
36 #define U300_WDOG_D1R 0x08
37 #define U300_WDOG_D1R_DISABLE1_DISABLE_TIMER 0x2BADU
38 /* WDOG_DISABLE2 Register 32bit (R/W) */
39 #define U300_WDOG_D2R 0x0C
40 #define U300_WDOG_D2R_DISABLE2_DISABLE_TIMER 0xCAFEU
41 #define U300_WDOG_D2R_DISABLE_STATUS_DISABLED 0xDABEU
42 #define U300_WDOG_D2R_DISABLE_STATUS_ENABLED 0x0000U
43 /* WDOG_STATUS Register 32bit (R/W) */
44 #define U300_WDOG_SR 0x10
45 #define U300_WDOG_SR_STATUS_TIMED_OUT 0xCFE8U
46 #define U300_WDOG_SR_STATUS_NORMAL 0x0000U
47 #define U300_WDOG_SR_RESET_STATUS_RESET 0xE8B4U
48 /* WDOG_COUNT Register 32bit (R/-) */
49 #define U300_WDOG_CR 0x14
50 #define U300_WDOG_CR_VALID_IND 0x8000U
51 #define U300_WDOG_CR_VALID_STABLE 0x0000U
52 #define U300_WDOG_CR_COUNT_VALUE_MASK 0x7FFFU
53 /* WDOG_JTAGOVR Register 32bit (R/W) */
54 #define U300_WDOG_JOR 0x18
55 #define U300_WDOG_JOR_JTAG_MODE_IND 0x0002U
56 #define U300_WDOG_JOR_JTAG_WATCHDOG_ENABLE 0x0001U
57 /* WDOG_RESTART Register 32bit (-/W) */
58 #define U300_WDOG_RR 0x1C
59 #define U300_WDOG_RR_RESTART_VALUE_RESUME 0xACEDU
60 /* WDOG_IRQ_EVENT Register 32bit (R/W) */
61 #define U300_WDOG_IER 0x20
62 #define U300_WDOG_IER_WILL_BARK_IRQ_EVENT_IND 0x0001U
63 #define U300_WDOG_IER_WILL_BARK_IRQ_ACK_ENABLE 0x0001U
64 /* WDOG_IRQ_MASK Register 32bit (R/W) */
65 #define U300_WDOG_IMR 0x24
66 #define U300_WDOG_IMR_WILL_BARK_IRQ_ENABLE 0x0001U
67 /* WDOG_IRQ_FORCE Register 32bit (R/W) */
68 #define U300_WDOG_IFR 0x28
69 #define U300_WDOG_IFR_WILL_BARK_IRQ_FORCE_ENABLE 0x0001U
70
71 /* Default timeout in seconds = 1 minute */
72 static int margin = 60;
73 static resource_size_t phybase;
74 static resource_size_t physize;
75 static int irq;
76 static void __iomem *virtbase;
77 static unsigned long coh901327_users;
78 static unsigned long boot_status;
79 static struct device *parent;
80
81 /*
82 * The watchdog block is of course always clocked, the
83 * clk_enable()/clk_disable() calls are mainly for performing reference
84 * counting higher up in the clock hierarchy.
85 */
86 static struct clk *clk;
87
88 /*
89 * Enabling and disabling functions.
90 */
coh901327_enable(u16 timeout)91 static void coh901327_enable(u16 timeout)
92 {
93 u16 val;
94 unsigned long freq;
95 unsigned long delay_ns;
96
97 clk_enable(clk);
98 /* Restart timer if it is disabled */
99 val = readw(virtbase + U300_WDOG_D2R);
100 if (val == U300_WDOG_D2R_DISABLE_STATUS_DISABLED)
101 writew(U300_WDOG_RR_RESTART_VALUE_RESUME,
102 virtbase + U300_WDOG_RR);
103 /* Acknowledge any pending interrupt so it doesn't just fire off */
104 writew(U300_WDOG_IER_WILL_BARK_IRQ_ACK_ENABLE,
105 virtbase + U300_WDOG_IER);
106 /*
107 * The interrupt is cleared in the 32 kHz clock domain.
108 * Wait 3 32 kHz cycles for it to take effect
109 */
110 freq = clk_get_rate(clk);
111 delay_ns = DIV_ROUND_UP(1000000000, freq); /* Freq to ns and round up */
112 delay_ns = 3 * delay_ns; /* Wait 3 cycles */
113 ndelay(delay_ns);
114 /* Enable the watchdog interrupt */
115 writew(U300_WDOG_IMR_WILL_BARK_IRQ_ENABLE, virtbase + U300_WDOG_IMR);
116 /* Activate the watchdog timer */
117 writew(timeout, virtbase + U300_WDOG_TR);
118 /* Start the watchdog timer */
119 writew(U300_WDOG_FR_FEED_RESTART_TIMER, virtbase + U300_WDOG_FR);
120 /*
121 * Extra read so that this change propagate in the watchdog.
122 */
123 (void) readw(virtbase + U300_WDOG_CR);
124 val = readw(virtbase + U300_WDOG_D2R);
125 clk_disable(clk);
126 if (val != U300_WDOG_D2R_DISABLE_STATUS_ENABLED)
127 dev_err(parent,
128 "%s(): watchdog not enabled! D2R value %04x\n",
129 __func__, val);
130 }
131
coh901327_disable(void)132 static void coh901327_disable(void)
133 {
134 u16 val;
135
136 clk_enable(clk);
137 /* Disable the watchdog interrupt if it is active */
138 writew(0x0000U, virtbase + U300_WDOG_IMR);
139 /* If the watchdog is currently enabled, attempt to disable it */
140 val = readw(virtbase + U300_WDOG_D2R);
141 if (val != U300_WDOG_D2R_DISABLE_STATUS_DISABLED) {
142 writew(U300_WDOG_D1R_DISABLE1_DISABLE_TIMER,
143 virtbase + U300_WDOG_D1R);
144 writew(U300_WDOG_D2R_DISABLE2_DISABLE_TIMER,
145 virtbase + U300_WDOG_D2R);
146 /* Write this twice (else problems occur) */
147 writew(U300_WDOG_D2R_DISABLE2_DISABLE_TIMER,
148 virtbase + U300_WDOG_D2R);
149 }
150 val = readw(virtbase + U300_WDOG_D2R);
151 clk_disable(clk);
152 if (val != U300_WDOG_D2R_DISABLE_STATUS_DISABLED)
153 dev_err(parent,
154 "%s(): watchdog not disabled! D2R value %04x\n",
155 __func__, val);
156 }
157
coh901327_start(void)158 static void coh901327_start(void)
159 {
160 coh901327_enable(margin * 100);
161 }
162
coh901327_keepalive(void)163 static void coh901327_keepalive(void)
164 {
165 clk_enable(clk);
166 /* Feed the watchdog */
167 writew(U300_WDOG_FR_FEED_RESTART_TIMER,
168 virtbase + U300_WDOG_FR);
169 clk_disable(clk);
170 }
171
coh901327_settimeout(int time)172 static int coh901327_settimeout(int time)
173 {
174 /*
175 * Max margin is 327 since the 10ms
176 * timeout register is max
177 * 0x7FFF = 327670ms ~= 327s.
178 */
179 if (time <= 0 || time > 327)
180 return -EINVAL;
181
182 margin = time;
183 clk_enable(clk);
184 /* Set new timeout value */
185 writew(margin * 100, virtbase + U300_WDOG_TR);
186 /* Feed the dog */
187 writew(U300_WDOG_FR_FEED_RESTART_TIMER,
188 virtbase + U300_WDOG_FR);
189 clk_disable(clk);
190 return 0;
191 }
192
193 /*
194 * This interrupt occurs 10 ms before the watchdog WILL bark.
195 */
coh901327_interrupt(int irq,void * data)196 static irqreturn_t coh901327_interrupt(int irq, void *data)
197 {
198 u16 val;
199
200 /*
201 * Ack IRQ? If this occurs we're FUBAR anyway, so
202 * just acknowledge, disable the interrupt and await the imminent end.
203 * If you at some point need a host of callbacks to be called
204 * when the system is about to watchdog-reset, add them here!
205 *
206 * NOTE: on future versions of this IP-block, it will be possible
207 * to prevent a watchdog reset by feeding the watchdog at this
208 * point.
209 */
210 clk_enable(clk);
211 val = readw(virtbase + U300_WDOG_IER);
212 if (val == U300_WDOG_IER_WILL_BARK_IRQ_EVENT_IND)
213 writew(U300_WDOG_IER_WILL_BARK_IRQ_ACK_ENABLE,
214 virtbase + U300_WDOG_IER);
215 writew(0x0000U, virtbase + U300_WDOG_IMR);
216 clk_disable(clk);
217 dev_crit(parent, "watchdog is barking!\n");
218 return IRQ_HANDLED;
219 }
220
221 /*
222 * Allow only one user (daemon) to open the watchdog
223 */
coh901327_open(struct inode * inode,struct file * file)224 static int coh901327_open(struct inode *inode, struct file *file)
225 {
226 if (test_and_set_bit(1, &coh901327_users))
227 return -EBUSY;
228 coh901327_start();
229 return nonseekable_open(inode, file);
230 }
231
coh901327_release(struct inode * inode,struct file * file)232 static int coh901327_release(struct inode *inode, struct file *file)
233 {
234 clear_bit(1, &coh901327_users);
235 coh901327_disable();
236 return 0;
237 }
238
coh901327_write(struct file * file,const char __user * data,size_t len,loff_t * ppos)239 static ssize_t coh901327_write(struct file *file, const char __user *data,
240 size_t len, loff_t *ppos)
241 {
242 if (len)
243 coh901327_keepalive();
244 return len;
245 }
246
coh901327_ioctl(struct file * file,unsigned int cmd,unsigned long arg)247 static long coh901327_ioctl(struct file *file, unsigned int cmd,
248 unsigned long arg)
249 {
250 int ret = -ENOTTY;
251 u16 val;
252 int time;
253 int new_options;
254 union {
255 struct watchdog_info __user *ident;
256 int __user *i;
257 } uarg;
258 static const struct watchdog_info ident = {
259 .options = WDIOF_CARDRESET |
260 WDIOF_SETTIMEOUT |
261 WDIOF_KEEPALIVEPING,
262 .identity = "COH 901 327 Watchdog",
263 .firmware_version = 1,
264 };
265 uarg.i = (int __user *)arg;
266
267 switch (cmd) {
268 case WDIOC_GETSUPPORT:
269 ret = copy_to_user(uarg.ident, &ident,
270 sizeof(ident)) ? -EFAULT : 0;
271 break;
272
273 case WDIOC_GETSTATUS:
274 ret = put_user(0, uarg.i);
275 break;
276
277 case WDIOC_GETBOOTSTATUS:
278 ret = put_user(boot_status, uarg.i);
279 break;
280
281 case WDIOC_SETOPTIONS:
282 ret = get_user(new_options, uarg.i);
283 if (ret)
284 break;
285 if (new_options & WDIOS_DISABLECARD)
286 coh901327_disable();
287 if (new_options & WDIOS_ENABLECARD)
288 coh901327_start();
289 ret = 0;
290 break;
291
292 case WDIOC_KEEPALIVE:
293 coh901327_keepalive();
294 ret = 0;
295 break;
296
297 case WDIOC_SETTIMEOUT:
298 ret = get_user(time, uarg.i);
299 if (ret)
300 break;
301
302 ret = coh901327_settimeout(time);
303 if (ret)
304 break;
305 /* Then fall through to return set value */
306
307 case WDIOC_GETTIMEOUT:
308 ret = put_user(margin, uarg.i);
309 break;
310
311 case WDIOC_GETTIMELEFT:
312 clk_enable(clk);
313 /* Read repeatedly until the value is stable! */
314 val = readw(virtbase + U300_WDOG_CR);
315 while (val & U300_WDOG_CR_VALID_IND)
316 val = readw(virtbase + U300_WDOG_CR);
317 val &= U300_WDOG_CR_COUNT_VALUE_MASK;
318 clk_disable(clk);
319 if (val != 0)
320 val /= 100;
321 ret = put_user(val, uarg.i);
322 break;
323 }
324 return ret;
325 }
326
327 static const struct file_operations coh901327_fops = {
328 .owner = THIS_MODULE,
329 .llseek = no_llseek,
330 .write = coh901327_write,
331 .unlocked_ioctl = coh901327_ioctl,
332 .open = coh901327_open,
333 .release = coh901327_release,
334 };
335
336 static struct miscdevice coh901327_miscdev = {
337 .minor = WATCHDOG_MINOR,
338 .name = "watchdog",
339 .fops = &coh901327_fops,
340 };
341
coh901327_remove(struct platform_device * pdev)342 static int __exit coh901327_remove(struct platform_device *pdev)
343 {
344 misc_deregister(&coh901327_miscdev);
345 coh901327_disable();
346 free_irq(irq, pdev);
347 clk_put(clk);
348 iounmap(virtbase);
349 release_mem_region(phybase, physize);
350 return 0;
351 }
352
353
coh901327_probe(struct platform_device * pdev)354 static int __init coh901327_probe(struct platform_device *pdev)
355 {
356 int ret;
357 u16 val;
358 struct resource *res;
359
360 res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
361 if (!res)
362 return -ENOENT;
363
364 parent = &pdev->dev;
365 physize = resource_size(res);
366 phybase = res->start;
367
368 if (request_mem_region(phybase, physize, DRV_NAME) == NULL) {
369 ret = -EBUSY;
370 goto out;
371 }
372
373 virtbase = ioremap(phybase, physize);
374 if (!virtbase) {
375 ret = -ENOMEM;
376 goto out_no_remap;
377 }
378
379 clk = clk_get(&pdev->dev, NULL);
380 if (IS_ERR(clk)) {
381 ret = PTR_ERR(clk);
382 dev_err(&pdev->dev, "could not get clock\n");
383 goto out_no_clk;
384 }
385 ret = clk_enable(clk);
386 if (ret) {
387 dev_err(&pdev->dev, "could not enable clock\n");
388 goto out_no_clk_enable;
389 }
390
391 val = readw(virtbase + U300_WDOG_SR);
392 switch (val) {
393 case U300_WDOG_SR_STATUS_TIMED_OUT:
394 dev_info(&pdev->dev,
395 "watchdog timed out since last chip reset!\n");
396 boot_status = WDIOF_CARDRESET;
397 /* Status will be cleared below */
398 break;
399 case U300_WDOG_SR_STATUS_NORMAL:
400 dev_info(&pdev->dev,
401 "in normal status, no timeouts have occurred.\n");
402 break;
403 default:
404 dev_info(&pdev->dev,
405 "contains an illegal status code (%08x)\n", val);
406 break;
407 }
408
409 val = readw(virtbase + U300_WDOG_D2R);
410 switch (val) {
411 case U300_WDOG_D2R_DISABLE_STATUS_DISABLED:
412 dev_info(&pdev->dev, "currently disabled.\n");
413 break;
414 case U300_WDOG_D2R_DISABLE_STATUS_ENABLED:
415 dev_info(&pdev->dev,
416 "currently enabled! (disabling it now)\n");
417 coh901327_disable();
418 break;
419 default:
420 dev_err(&pdev->dev,
421 "contains an illegal enable/disable code (%08x)\n",
422 val);
423 break;
424 }
425
426 /* Reset the watchdog */
427 writew(U300_WDOG_SR_RESET_STATUS_RESET, virtbase + U300_WDOG_SR);
428
429 irq = platform_get_irq(pdev, 0);
430 if (request_irq(irq, coh901327_interrupt, 0,
431 DRV_NAME " Bark", pdev)) {
432 ret = -EIO;
433 goto out_no_irq;
434 }
435
436 clk_disable(clk);
437
438 ret = misc_register(&coh901327_miscdev);
439 if (ret == 0)
440 dev_info(&pdev->dev,
441 "initialized. timer margin=%d sec\n", margin);
442 else
443 goto out_no_wdog;
444
445 return 0;
446
447 out_no_wdog:
448 free_irq(irq, pdev);
449 out_no_irq:
450 clk_disable(clk);
451 out_no_clk_enable:
452 clk_put(clk);
453 out_no_clk:
454 iounmap(virtbase);
455 out_no_remap:
456 release_mem_region(phybase, SZ_4K);
457 out:
458 return ret;
459 }
460
461 #ifdef CONFIG_PM
462
463 static u16 wdogenablestore;
464 static u16 irqmaskstore;
465
coh901327_suspend(struct platform_device * pdev,pm_message_t state)466 static int coh901327_suspend(struct platform_device *pdev, pm_message_t state)
467 {
468 irqmaskstore = readw(virtbase + U300_WDOG_IMR) & 0x0001U;
469 wdogenablestore = readw(virtbase + U300_WDOG_D2R);
470 /* If watchdog is on, disable it here and now */
471 if (wdogenablestore == U300_WDOG_D2R_DISABLE_STATUS_ENABLED)
472 coh901327_disable();
473 return 0;
474 }
475
coh901327_resume(struct platform_device * pdev)476 static int coh901327_resume(struct platform_device *pdev)
477 {
478 /* Restore the watchdog interrupt */
479 writew(irqmaskstore, virtbase + U300_WDOG_IMR);
480 if (wdogenablestore == U300_WDOG_D2R_DISABLE_STATUS_ENABLED) {
481 /* Restart the watchdog timer */
482 writew(U300_WDOG_RR_RESTART_VALUE_RESUME,
483 virtbase + U300_WDOG_RR);
484 writew(U300_WDOG_FR_FEED_RESTART_TIMER,
485 virtbase + U300_WDOG_FR);
486 }
487 return 0;
488 }
489 #else
490 #define coh901327_suspend NULL
491 #define coh901327_resume NULL
492 #endif
493
494 /*
495 * Mistreating the watchdog is the only way to perform a software reset of the
496 * system on EMP platforms. So we implement this and export a symbol for it.
497 */
coh901327_watchdog_reset(void)498 void coh901327_watchdog_reset(void)
499 {
500 /* Enable even if on JTAG too */
501 writew(U300_WDOG_JOR_JTAG_WATCHDOG_ENABLE,
502 virtbase + U300_WDOG_JOR);
503 /*
504 * Timeout = 5s, we have to wait for the watchdog reset to
505 * actually take place: the watchdog will be reloaded with the
506 * default value immediately, so we HAVE to reboot and get back
507 * into the kernel in 30s, or the device will reboot again!
508 * The boot loader will typically deactivate the watchdog, so we
509 * need time enough for the boot loader to get to the point of
510 * deactivating the watchdog before it is shut down by it.
511 *
512 * NOTE: on future versions of the watchdog, this restriction is
513 * gone: the watchdog will be reloaded with a default value (1 min)
514 * instead of last value, and you can conveniently set the watchdog
515 * timeout to 10ms (value = 1) without any problems.
516 */
517 coh901327_enable(500);
518 /* Return and await doom */
519 }
520
521 static struct platform_driver coh901327_driver = {
522 .driver = {
523 .owner = THIS_MODULE,
524 .name = "coh901327_wdog",
525 },
526 .remove = __exit_p(coh901327_remove),
527 .suspend = coh901327_suspend,
528 .resume = coh901327_resume,
529 };
530
coh901327_init(void)531 static int __init coh901327_init(void)
532 {
533 return platform_driver_probe(&coh901327_driver, coh901327_probe);
534 }
535 module_init(coh901327_init);
536
coh901327_exit(void)537 static void __exit coh901327_exit(void)
538 {
539 platform_driver_unregister(&coh901327_driver);
540 }
541 module_exit(coh901327_exit);
542
543 MODULE_AUTHOR("Linus Walleij <linus.walleij@stericsson.com>");
544 MODULE_DESCRIPTION("COH 901 327 Watchdog");
545
546 module_param(margin, int, 0);
547 MODULE_PARM_DESC(margin, "Watchdog margin in seconds (default 60s)");
548
549 MODULE_LICENSE("GPL");
550 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
551