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Linux/drivers/watchdog/ts72xx_wdt.c

  1 /*
  2  * Watchdog driver for Technologic Systems TS-72xx based SBCs
  3  * (TS-7200, TS-7250 and TS-7260). These boards have external
  4  * glue logic CPLD chip, which includes programmable watchdog
  5  * timer.
  6  *
  7  * Copyright (c) 2009 Mika Westerberg <mika.westerberg@iki.fi>
  8  *
  9  * This driver is based on ep93xx_wdt and wm831x_wdt drivers.
 10  *
 11  * This file is licensed under the terms of the GNU General Public
 12  * License version 2. This program is licensed "as is" without any
 13  * warranty of any kind, whether express or implied.
 14  */
 15 
 16 #include <linux/fs.h>
 17 #include <linux/io.h>
 18 #include <linux/module.h>
 19 #include <linux/moduleparam.h>
 20 #include <linux/miscdevice.h>
 21 #include <linux/mutex.h>
 22 #include <linux/platform_device.h>
 23 #include <linux/slab.h>
 24 #include <linux/watchdog.h>
 25 #include <linux/uaccess.h>
 26 
 27 #define TS72XX_WDT_FEED_VAL             0x05
 28 #define TS72XX_WDT_DEFAULT_TIMEOUT      8
 29 
 30 static int timeout = TS72XX_WDT_DEFAULT_TIMEOUT;
 31 module_param(timeout, int, 0);
 32 MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds. "
 33                           "(1 <= timeout <= 8, default="
 34                           __MODULE_STRING(TS72XX_WDT_DEFAULT_TIMEOUT)
 35                           ")");
 36 
 37 static bool nowayout = WATCHDOG_NOWAYOUT;
 38 module_param(nowayout, bool, 0);
 39 MODULE_PARM_DESC(nowayout, "Disable watchdog shutdown on close");
 40 
 41 /**
 42  * struct ts72xx_wdt - watchdog control structure
 43  * @lock: lock that protects this structure
 44  * @regval: watchdog timeout value suitable for control register
 45  * @flags: flags controlling watchdog device state
 46  * @control_reg: watchdog control register
 47  * @feed_reg: watchdog feed register
 48  * @pdev: back pointer to platform dev
 49  */
 50 struct ts72xx_wdt {
 51         struct mutex    lock;
 52         int             regval;
 53 
 54 #define TS72XX_WDT_BUSY_FLAG            1
 55 #define TS72XX_WDT_EXPECT_CLOSE_FLAG    2
 56         int             flags;
 57 
 58         void __iomem    *control_reg;
 59         void __iomem    *feed_reg;
 60 
 61         struct platform_device *pdev;
 62 };
 63 
 64 static struct platform_device *ts72xx_wdt_pdev;
 65 
 66 /*
 67  * TS-72xx Watchdog supports following timeouts (value written
 68  * to control register):
 69  *      value   description
 70  *      -------------------------
 71  *      0x00    watchdog disabled
 72  *      0x01    250ms
 73  *      0x02    500ms
 74  *      0x03    1s
 75  *      0x04    reserved
 76  *      0x05    2s
 77  *      0x06    4s
 78  *      0x07    8s
 79  *
 80  * Timeouts below 1s are not very usable so we don't
 81  * allow them at all.
 82  *
 83  * We provide two functions that convert between these:
 84  * timeout_to_regval() and regval_to_timeout().
 85  */
 86 static const struct {
 87         int     timeout;
 88         int     regval;
 89 } ts72xx_wdt_map[] = {
 90         { 1, 3 },
 91         { 2, 5 },
 92         { 4, 6 },
 93         { 8, 7 },
 94 };
 95 
 96 /**
 97  * timeout_to_regval() - converts given timeout to control register value
 98  * @new_timeout: timeout in seconds to be converted
 99  *
100  * Function converts given @new_timeout into valid value that can
101  * be programmed into watchdog control register. When conversion is
102  * not possible, function returns %-EINVAL.
103  */
104 static int timeout_to_regval(int new_timeout)
105 {
106         int i;
107 
108         /* first limit it to 1 - 8 seconds */
109         new_timeout = clamp_val(new_timeout, 1, 8);
110 
111         for (i = 0; i < ARRAY_SIZE(ts72xx_wdt_map); i++) {
112                 if (ts72xx_wdt_map[i].timeout >= new_timeout)
113                         return ts72xx_wdt_map[i].regval;
114         }
115 
116         return -EINVAL;
117 }
118 
119 /**
120  * regval_to_timeout() - converts control register value to timeout
121  * @regval: control register value to be converted
122  *
123  * Function converts given @regval to timeout in seconds (1, 2, 4 or 8).
124  * If @regval cannot be converted, function returns %-EINVAL.
125  */
126 static int regval_to_timeout(int regval)
127 {
128         int i;
129 
130         for (i = 0; i < ARRAY_SIZE(ts72xx_wdt_map); i++) {
131                 if (ts72xx_wdt_map[i].regval == regval)
132                         return ts72xx_wdt_map[i].timeout;
133         }
134 
135         return -EINVAL;
136 }
137 
138 /**
139  * ts72xx_wdt_kick() - kick the watchdog
140  * @wdt: watchdog to be kicked
141  *
142  * Called with @wdt->lock held.
143  */
144 static inline void ts72xx_wdt_kick(struct ts72xx_wdt *wdt)
145 {
146         __raw_writeb(TS72XX_WDT_FEED_VAL, wdt->feed_reg);
147 }
148 
149 /**
150  * ts72xx_wdt_start() - starts the watchdog timer
151  * @wdt: watchdog to be started
152  *
153  * This function programs timeout to watchdog timer
154  * and starts it.
155  *
156  * Called with @wdt->lock held.
157  */
158 static void ts72xx_wdt_start(struct ts72xx_wdt *wdt)
159 {
160         /*
161          * To program the wdt, it first must be "fed" and
162          * only after that (within 30 usecs) the configuration
163          * can be changed.
164          */
165         ts72xx_wdt_kick(wdt);
166         __raw_writeb((u8)wdt->regval, wdt->control_reg);
167 }
168 
169 /**
170  * ts72xx_wdt_stop() - stops the watchdog timer
171  * @wdt: watchdog to be stopped
172  *
173  * Called with @wdt->lock held.
174  */
175 static void ts72xx_wdt_stop(struct ts72xx_wdt *wdt)
176 {
177         ts72xx_wdt_kick(wdt);
178         __raw_writeb(0, wdt->control_reg);
179 }
180 
181 static int ts72xx_wdt_open(struct inode *inode, struct file *file)
182 {
183         struct ts72xx_wdt *wdt = platform_get_drvdata(ts72xx_wdt_pdev);
184         int regval;
185 
186         /*
187          * Try to convert default timeout to valid register
188          * value first.
189          */
190         regval = timeout_to_regval(timeout);
191         if (regval < 0) {
192                 dev_err(&wdt->pdev->dev,
193                         "failed to convert timeout (%d) to register value\n",
194                         timeout);
195                 return regval;
196         }
197 
198         if (mutex_lock_interruptible(&wdt->lock))
199                 return -ERESTARTSYS;
200 
201         if ((wdt->flags & TS72XX_WDT_BUSY_FLAG) != 0) {
202                 mutex_unlock(&wdt->lock);
203                 return -EBUSY;
204         }
205 
206         wdt->flags = TS72XX_WDT_BUSY_FLAG;
207         wdt->regval = regval;
208         file->private_data = wdt;
209 
210         ts72xx_wdt_start(wdt);
211 
212         mutex_unlock(&wdt->lock);
213         return nonseekable_open(inode, file);
214 }
215 
216 static int ts72xx_wdt_release(struct inode *inode, struct file *file)
217 {
218         struct ts72xx_wdt *wdt = file->private_data;
219 
220         if (mutex_lock_interruptible(&wdt->lock))
221                 return -ERESTARTSYS;
222 
223         if ((wdt->flags & TS72XX_WDT_EXPECT_CLOSE_FLAG) != 0) {
224                 ts72xx_wdt_stop(wdt);
225         } else {
226                 dev_warn(&wdt->pdev->dev,
227                          "TS-72XX WDT device closed unexpectly. "
228                          "Watchdog timer will not stop!\n");
229                 /*
230                  * Kick it one more time, to give userland some time
231                  * to recover (for example, respawning the kicker
232                  * daemon).
233                  */
234                 ts72xx_wdt_kick(wdt);
235         }
236 
237         wdt->flags = 0;
238 
239         mutex_unlock(&wdt->lock);
240         return 0;
241 }
242 
243 static ssize_t ts72xx_wdt_write(struct file *file,
244                                 const char __user *data,
245                                 size_t len,
246                                 loff_t *ppos)
247 {
248         struct ts72xx_wdt *wdt = file->private_data;
249 
250         if (!len)
251                 return 0;
252 
253         if (mutex_lock_interruptible(&wdt->lock))
254                 return -ERESTARTSYS;
255 
256         ts72xx_wdt_kick(wdt);
257 
258         /*
259          * Support for magic character closing. User process
260          * writes 'V' into the device, just before it is closed.
261          * This means that we know that the wdt timer can be
262          * stopped after user closes the device.
263          */
264         if (!nowayout) {
265                 int i;
266 
267                 for (i = 0; i < len; i++) {
268                         char c;
269 
270                         /* In case it was set long ago */
271                         wdt->flags &= ~TS72XX_WDT_EXPECT_CLOSE_FLAG;
272 
273                         if (get_user(c, data + i)) {
274                                 mutex_unlock(&wdt->lock);
275                                 return -EFAULT;
276                         }
277                         if (c == 'V') {
278                                 wdt->flags |= TS72XX_WDT_EXPECT_CLOSE_FLAG;
279                                 break;
280                         }
281                 }
282         }
283 
284         mutex_unlock(&wdt->lock);
285         return len;
286 }
287 
288 static const struct watchdog_info winfo = {
289         .options                = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT |
290                                   WDIOF_MAGICCLOSE,
291         .firmware_version       = 1,
292         .identity               = "TS-72XX WDT",
293 };
294 
295 static long ts72xx_wdt_ioctl(struct file *file, unsigned int cmd,
296                              unsigned long arg)
297 {
298         struct ts72xx_wdt *wdt = file->private_data;
299         void __user *argp = (void __user *)arg;
300         int __user *p = (int __user *)argp;
301         int error = 0;
302 
303         if (mutex_lock_interruptible(&wdt->lock))
304                 return -ERESTARTSYS;
305 
306         switch (cmd) {
307         case WDIOC_GETSUPPORT:
308                 if (copy_to_user(argp, &winfo, sizeof(winfo)))
309                         error = -EFAULT;
310                 break;
311 
312         case WDIOC_GETSTATUS:
313         case WDIOC_GETBOOTSTATUS:
314                 error = put_user(0, p);
315                 break;
316 
317         case WDIOC_KEEPALIVE:
318                 ts72xx_wdt_kick(wdt);
319                 break;
320 
321         case WDIOC_SETOPTIONS: {
322                 int options;
323 
324                 error = get_user(options, p);
325                 if (error)
326                         break;
327 
328                 error = -EINVAL;
329 
330                 if ((options & WDIOS_DISABLECARD) != 0) {
331                         ts72xx_wdt_stop(wdt);
332                         error = 0;
333                 }
334                 if ((options & WDIOS_ENABLECARD) != 0) {
335                         ts72xx_wdt_start(wdt);
336                         error = 0;
337                 }
338 
339                 break;
340         }
341 
342         case WDIOC_SETTIMEOUT: {
343                 int new_timeout;
344                 int regval;
345 
346                 error = get_user(new_timeout, p);
347                 if (error)
348                         break;
349 
350                 regval = timeout_to_regval(new_timeout);
351                 if (regval < 0) {
352                         error = regval;
353                         break;
354                 }
355                 ts72xx_wdt_stop(wdt);
356                 wdt->regval = regval;
357                 ts72xx_wdt_start(wdt);
358 
359                 /*FALLTHROUGH*/
360         }
361 
362         case WDIOC_GETTIMEOUT:
363                 error = put_user(regval_to_timeout(wdt->regval), p);
364                 break;
365 
366         default:
367                 error = -ENOTTY;
368                 break;
369         }
370 
371         mutex_unlock(&wdt->lock);
372         return error;
373 }
374 
375 static const struct file_operations ts72xx_wdt_fops = {
376         .owner          = THIS_MODULE,
377         .llseek         = no_llseek,
378         .open           = ts72xx_wdt_open,
379         .release        = ts72xx_wdt_release,
380         .write          = ts72xx_wdt_write,
381         .unlocked_ioctl = ts72xx_wdt_ioctl,
382 };
383 
384 static struct miscdevice ts72xx_wdt_miscdev = {
385         .minor          = WATCHDOG_MINOR,
386         .name           = "watchdog",
387         .fops           = &ts72xx_wdt_fops,
388 };
389 
390 static int ts72xx_wdt_probe(struct platform_device *pdev)
391 {
392         struct ts72xx_wdt *wdt;
393         struct resource *r1, *r2;
394         int error = 0;
395 
396         wdt = devm_kzalloc(&pdev->dev, sizeof(struct ts72xx_wdt), GFP_KERNEL);
397         if (!wdt)
398                 return -ENOMEM;
399 
400         r1 = platform_get_resource(pdev, IORESOURCE_MEM, 0);
401         wdt->control_reg = devm_ioremap_resource(&pdev->dev, r1);
402         if (IS_ERR(wdt->control_reg))
403                 return PTR_ERR(wdt->control_reg);
404 
405         r2 = platform_get_resource(pdev, IORESOURCE_MEM, 1);
406         wdt->feed_reg = devm_ioremap_resource(&pdev->dev, r2);
407         if (IS_ERR(wdt->feed_reg))
408                 return PTR_ERR(wdt->feed_reg);
409 
410         platform_set_drvdata(pdev, wdt);
411         ts72xx_wdt_pdev = pdev;
412         wdt->pdev = pdev;
413         mutex_init(&wdt->lock);
414 
415         /* make sure that the watchdog is disabled */
416         ts72xx_wdt_stop(wdt);
417 
418         error = misc_register(&ts72xx_wdt_miscdev);
419         if (error) {
420                 dev_err(&pdev->dev, "failed to register miscdev\n");
421                 return error;
422         }
423 
424         dev_info(&pdev->dev, "TS-72xx Watchdog driver\n");
425 
426         return 0;
427 }
428 
429 static int ts72xx_wdt_remove(struct platform_device *pdev)
430 {
431         int error;
432 
433         error = misc_deregister(&ts72xx_wdt_miscdev);
434 
435         return error;
436 }
437 
438 static struct platform_driver ts72xx_wdt_driver = {
439         .probe          = ts72xx_wdt_probe,
440         .remove         = ts72xx_wdt_remove,
441         .driver         = {
442                 .name   = "ts72xx-wdt",
443                 .owner  = THIS_MODULE,
444         },
445 };
446 
447 module_platform_driver(ts72xx_wdt_driver);
448 
449 MODULE_AUTHOR("Mika Westerberg <mika.westerberg@iki.fi>");
450 MODULE_DESCRIPTION("TS-72xx SBC Watchdog");
451 MODULE_LICENSE("GPL");
452 MODULE_ALIAS("platform:ts72xx-wdt");
453 

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