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Merge branch 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/nab/target...
[linux-btrfs-devel.git] / drivers / watchdog / of_xilinx_wdt.c
blob4ec741ac952c292c4578b5148d3e840c2d9c73a1
1 /*
2 * of_xilinx_wdt.c 1.01 A Watchdog Device Driver for Xilinx xps_timebase_wdt
3 *
4 * (C) Copyright 2011 (Alejandro Cabrera <aldaya@gmail.com>)
5 *
6 * -----------------------
7 *
8 * This program is free software; you can redistribute it and/or
9 * modify it under the terms of the GNU General Public License
10 * as published by the Free Software Foundation; either version
11 * 2 of the License, or (at your option) any later version.
12 *
13 * -----------------------
14 * 30-May-2011 Alejandro Cabrera <aldaya@gmail.com>
15 * - If "xlnx,wdt-enable-once" wasn't found on device tree the
16 * module will use CONFIG_WATCHDOG_NOWAYOUT
17 * - If the device tree parameters ("clock-frequency" and
18 * "xlnx,wdt-interval") wasn't found the driver won't
19 * know the wdt reset interval
20 */
21
22 #include <linux/module.h>
23 #include <linux/types.h>
24 #include <linux/kernel.h>
25 #include <linux/fs.h>
26 #include <linux/miscdevice.h>
27 #include <linux/init.h>
28 #include <linux/ioport.h>
29 #include <linux/watchdog.h>
30 #include <linux/io.h>
31 #include <linux/uaccess.h>
32 #include <linux/of.h>
33 #include <linux/of_device.h>
34 #include <linux/of_address.h>
35
36 /* Register offsets for the Wdt device */
37 #define XWT_TWCSR0_OFFSET 0x0 /* Control/Status Register0 */
38 #define XWT_TWCSR1_OFFSET 0x4 /* Control/Status Register1 */
39 #define XWT_TBR_OFFSET 0x8 /* Timebase Register Offset */
40
41 /* Control/Status Register Masks */
42 #define XWT_CSR0_WRS_MASK 0x00000008 /* Reset status */
43 #define XWT_CSR0_WDS_MASK 0x00000004 /* Timer state */
44 #define XWT_CSR0_EWDT1_MASK 0x00000002 /* Enable bit 1 */
45
46 /* Control/Status Register 0/1 bits */
47 #define XWT_CSRX_EWDT2_MASK 0x00000001 /* Enable bit 2 */
48
49 /* SelfTest constants */
50 #define XWT_MAX_SELFTEST_LOOP_COUNT 0x00010000
51 #define XWT_TIMER_FAILED 0xFFFFFFFF
52
53 #define WATCHDOG_NAME "Xilinx Watchdog"
54 #define PFX WATCHDOG_NAME ": "
55
56 struct xwdt_device {
57 struct resource res;
58 void __iomem *base;
59 u32 nowayout;
60 u32 wdt_interval;
61 u32 boot_status;
62 };
63
64 static struct xwdt_device xdev;
65
66 static u32 timeout;
67 static u32 control_status_reg;
68 static u8 expect_close;
69 static u8 no_timeout;
70 static unsigned long driver_open;
71
72 static DEFINE_SPINLOCK(spinlock);
73
74 static void xwdt_start(void)
75 {
76 spin_lock(&spinlock);
77
78 /* Clean previous status and enable the watchdog timer */
79 control_status_reg = ioread32(xdev.base + XWT_TWCSR0_OFFSET);
80 control_status_reg |= (XWT_CSR0_WRS_MASK | XWT_CSR0_WDS_MASK);
81
82 iowrite32((control_status_reg | XWT_CSR0_EWDT1_MASK),
83 xdev.base + XWT_TWCSR0_OFFSET);
84
85 iowrite32(XWT_CSRX_EWDT2_MASK, xdev.base + XWT_TWCSR1_OFFSET);
86
87 spin_unlock(&spinlock);
88 }
89
90 static void xwdt_stop(void)
91 {
92 spin_lock(&spinlock);
93
94 control_status_reg = ioread32(xdev.base + XWT_TWCSR0_OFFSET);
95
96 iowrite32((control_status_reg & ~XWT_CSR0_EWDT1_MASK),
97 xdev.base + XWT_TWCSR0_OFFSET);
98
99 iowrite32(0, xdev.base + XWT_TWCSR1_OFFSET);
100
101 spin_unlock(&spinlock);
102 printk(KERN_INFO PFX "Stopped!\n");
103 }
104
105 static void xwdt_keepalive(void)
106 {
107 spin_lock(&spinlock);
108
109 control_status_reg = ioread32(xdev.base + XWT_TWCSR0_OFFSET);
110 control_status_reg |= (XWT_CSR0_WRS_MASK | XWT_CSR0_WDS_MASK);
111 iowrite32(control_status_reg, xdev.base + XWT_TWCSR0_OFFSET);
112
113 spin_unlock(&spinlock);
114 }
115
116 static void xwdt_get_status(int *status)
117 {
118 int new_status;
119
120 spin_lock(&spinlock);
121
122 control_status_reg = ioread32(xdev.base + XWT_TWCSR0_OFFSET);
123 new_status = ((control_status_reg &
124 (XWT_CSR0_WRS_MASK | XWT_CSR0_WDS_MASK)) != 0);
125 spin_unlock(&spinlock);
126
127 *status = 0;
128 if (new_status & 1)
129 *status |= WDIOF_CARDRESET;
130 }
131
132 static u32 xwdt_selftest(void)
133 {
134 int i;
135 u32 timer_value1;
136 u32 timer_value2;
137
138 spin_lock(&spinlock);
139
140 timer_value1 = ioread32(xdev.base + XWT_TBR_OFFSET);
141 timer_value2 = ioread32(xdev.base + XWT_TBR_OFFSET);
142
143 for (i = 0;
144 ((i <= XWT_MAX_SELFTEST_LOOP_COUNT) &&
145 (timer_value2 == timer_value1)); i++) {
146 timer_value2 = ioread32(xdev.base + XWT_TBR_OFFSET);
147 }
148
149 spin_unlock(&spinlock);
150
151 if (timer_value2 != timer_value1)
152 return ~XWT_TIMER_FAILED;
153 else
154 return XWT_TIMER_FAILED;
155 }
156
157 static int xwdt_open(struct inode *inode, struct file *file)
158 {
159 /* Only one process can handle the wdt at a time */
160 if (test_and_set_bit(0, &driver_open))
161 return -EBUSY;
162
163 /* Make sure that the module are always loaded...*/
164 if (xdev.nowayout)
165 __module_get(THIS_MODULE);
166
167 xwdt_start();
168 printk(KERN_INFO PFX "Started...\n");
169
170 return nonseekable_open(inode, file);
171 }
172
173 static int xwdt_release(struct inode *inode, struct file *file)
174 {
175 if (expect_close == 42) {
176 xwdt_stop();
177 } else {
178 printk(KERN_CRIT PFX
179 "Unexpected close, not stopping watchdog!\n");
180 xwdt_keepalive();
181 }
182
183 clear_bit(0, &driver_open);
184 expect_close = 0;
185 return 0;
186 }
187
188 /*
189 * xwdt_write:
190 * @file: file handle to the watchdog
191 * @buf: buffer to write (unused as data does not matter here
192 * @count: count of bytes
193 * @ppos: pointer to the position to write. No seeks allowed
194 *
195 * A write to a watchdog device is defined as a keepalive signal. Any
196 * write of data will do, as we don't define content meaning.
197 */
198 static ssize_t xwdt_write(struct file *file, const char __user *buf,
199 size_t len, loff_t *ppos)
200 {
201 if (len) {
202 if (!xdev.nowayout) {
203 size_t i;
204
205 /* In case it was set long ago */
206 expect_close = 0;
207
208 for (i = 0; i != len; i++) {
209 char c;
210
211 if (get_user(c, buf + i))
212 return -EFAULT;
213 if (c == 'V')
214 expect_close = 42;
215 }
216 }
217 xwdt_keepalive();
218 }
219 return len;
220 }
221
222 static const struct watchdog_info ident = {
223 .options = WDIOF_MAGICCLOSE |
224 WDIOF_KEEPALIVEPING,
225 .firmware_version = 1,
226 .identity = WATCHDOG_NAME,
227 };
228
229 /*
230 * xwdt_ioctl:
231 * @file: file handle to the device
232 * @cmd: watchdog command
233 * @arg: argument pointer
234 *
235 * The watchdog API defines a common set of functions for all watchdogs
236 * according to their available features.
237 */
238 static long xwdt_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
239 {
240 int status;
241
242 union {
243 struct watchdog_info __user *ident;
244 int __user *i;
245 } uarg;
246
247 uarg.i = (int __user *)arg;
248
249 switch (cmd) {
250 case WDIOC_GETSUPPORT:
251 return copy_to_user(uarg.ident, &ident,
252 sizeof(ident)) ? -EFAULT : 0;
253
254 case WDIOC_GETBOOTSTATUS:
255 return put_user(xdev.boot_status, uarg.i);
256
257 case WDIOC_GETSTATUS:
258 xwdt_get_status(&status);
259 return put_user(status, uarg.i);
260
261 case WDIOC_KEEPALIVE:
262 xwdt_keepalive();
263 return 0;
264
265 case WDIOC_GETTIMEOUT:
266 if (no_timeout)
267 return -ENOTTY;
268 else
269 return put_user(timeout, uarg.i);
270
271 default:
272 return -ENOTTY;
273 }
274 }
275
276 static const struct file_operations xwdt_fops = {
277 .owner = THIS_MODULE,
278 .llseek = no_llseek,
279 .write = xwdt_write,
280 .open = xwdt_open,
281 .release = xwdt_release,
282 .unlocked_ioctl = xwdt_ioctl,
283 };
284
285 static struct miscdevice xwdt_miscdev = {
286 .minor = WATCHDOG_MINOR,
287 .name = "watchdog",
288 .fops = &xwdt_fops,
289 };
290
291 static int __devinit xwdt_probe(struct platform_device *pdev)
292 {
293 int rc;
294 u32 *tmptr;
295 u32 *pfreq;
296
297 no_timeout = 0;
298
299 pfreq = (u32 *)of_get_property(pdev->dev.of_node->parent,
300 "clock-frequency", NULL);
301
302 if (pfreq == NULL) {
303 printk(KERN_WARNING PFX
304 "The watchdog clock frequency cannot be obtained!\n");
305 no_timeout = 1;
306 }
307
308 rc = of_address_to_resource(pdev->dev.of_node, 0, &xdev.res);
309 if (rc) {
310 printk(KERN_WARNING PFX "invalid address!\n");
311 return rc;
312 }
313
314 tmptr = (u32 *)of_get_property(pdev->dev.of_node,
315 "xlnx,wdt-interval", NULL);
316 if (tmptr == NULL) {
317 printk(KERN_WARNING PFX "Parameter \"xlnx,wdt-interval\""
318 " not found in device tree!\n");
319 no_timeout = 1;
320 } else {
321 xdev.wdt_interval = *tmptr;
322 }
323
324 tmptr = (u32 *)of_get_property(pdev->dev.of_node,
325 "xlnx,wdt-enable-once", NULL);
326 if (tmptr == NULL) {
327 printk(KERN_WARNING PFX "Parameter \"xlnx,wdt-enable-once\""
328 " not found in device tree!\n");
329 xdev.nowayout = WATCHDOG_NOWAYOUT;
330 }
331
332 /*
333 * Twice of the 2^wdt_interval / freq because the first wdt overflow is
334 * ignored (interrupt), reset is only generated at second wdt overflow
335 */
336 if (!no_timeout)
337 timeout = 2 * ((1<<xdev.wdt_interval) / *pfreq);
338
339 if (!request_mem_region(xdev.res.start,
340 xdev.res.end - xdev.res.start + 1, WATCHDOG_NAME)) {
341 rc = -ENXIO;
342 printk(KERN_ERR PFX "memory request failure!\n");
343 goto err_out;
344 }
345
346 xdev.base = ioremap(xdev.res.start, xdev.res.end - xdev.res.start + 1);
347 if (xdev.base == NULL) {
348 rc = -ENOMEM;
349 printk(KERN_ERR PFX "ioremap failure!\n");
350 goto release_mem;
351 }
352
353 rc = xwdt_selftest();
354 if (rc == XWT_TIMER_FAILED) {
355 printk(KERN_ERR PFX "SelfTest routine error!\n");
356 goto unmap_io;
357 }
358
359 xwdt_get_status(&xdev.boot_status);
360
361 rc = misc_register(&xwdt_miscdev);
362 if (rc) {
363 printk(KERN_ERR PFX
364 "cannot register miscdev on minor=%d (err=%d)\n",
365 xwdt_miscdev.minor, rc);
366 goto unmap_io;
367 }
368
369 if (no_timeout)
370 printk(KERN_INFO PFX
371 "driver loaded (timeout=? sec, nowayout=%d)\n",
372 xdev.nowayout);
373 else
374 printk(KERN_INFO PFX
375 "driver loaded (timeout=%d sec, nowayout=%d)\n",
376 timeout, xdev.nowayout);
377
378 expect_close = 0;
379 clear_bit(0, &driver_open);
380
381 return 0;
382
383 unmap_io:
384 iounmap(xdev.base);
385 release_mem:
386 release_mem_region(xdev.res.start, resource_size(&xdev.res));
387 err_out:
388 return rc;
389 }
390
391 static int __devexit xwdt_remove(struct platform_device *dev)
392 {
393 misc_deregister(&xwdt_miscdev);
394 iounmap(xdev.base);
395 release_mem_region(xdev.res.start, resource_size(&xdev.res));
396
397 return 0;
398 }
399
400 /* Match table for of_platform binding */
401 static struct of_device_id __devinitdata xwdt_of_match[] = {
402 { .compatible = "xlnx,xps-timebase-wdt-1.01.a", },
403 {},
404 };
405 MODULE_DEVICE_TABLE(of, xwdt_of_match);
406
407 static struct platform_driver xwdt_driver = {
408 .probe = xwdt_probe,
409 .remove = __devexit_p(xwdt_remove),
410 .driver = {
411 .owner = THIS_MODULE,
412 .name = WATCHDOG_NAME,
413 .of_match_table = xwdt_of_match,
414 },
415 };
416
417 static int __init xwdt_init(void)
418 {
419 return platform_driver_register(&xwdt_driver);
420 }
421
422 static void __exit xwdt_exit(void)
423 {
424 platform_driver_unregister(&xwdt_driver);
425 }
426
427 module_init(xwdt_init);
428 module_exit(xwdt_exit);
429
430 MODULE_AUTHOR("Alejandro Cabrera <aldaya@gmail.com>");
431 MODULE_DESCRIPTION("Xilinx Watchdog driver");
432 MODULE_LICENSE("GPL");
433 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
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