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Linux/drivers/watchdog/at91sam9_wdt.c

  1 /*
  2  * Watchdog driver for Atmel AT91SAM9x processors.
  3  *
  4  * Copyright (C) 2008 Renaud CERRATO r.cerrato@til-technologies.fr
  5  *
  6  * This program is free software; you can redistribute it and/or
  7  * modify it under the terms of the GNU General Public License
  8  * as published by the Free Software Foundation; either version
  9  * 2 of the License, or (at your option) any later version.
 10  */
 11 
 12 /*
 13  * The Watchdog Timer Mode Register can be only written to once. If the
 14  * timeout need to be set from Linux, be sure that the bootstrap or the
 15  * bootloader doesn't write to this register.
 16  */
 17 
 18 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 19 
 20 #include <linux/errno.h>
 21 #include <linux/init.h>
 22 #include <linux/interrupt.h>
 23 #include <linux/io.h>
 24 #include <linux/kernel.h>
 25 #include <linux/module.h>
 26 #include <linux/moduleparam.h>
 27 #include <linux/platform_device.h>
 28 #include <linux/reboot.h>
 29 #include <linux/types.h>
 30 #include <linux/watchdog.h>
 31 #include <linux/jiffies.h>
 32 #include <linux/timer.h>
 33 #include <linux/bitops.h>
 34 #include <linux/uaccess.h>
 35 #include <linux/of.h>
 36 #include <linux/of_irq.h>
 37 
 38 #include "at91sam9_wdt.h"
 39 
 40 #define DRV_NAME "AT91SAM9 Watchdog"
 41 
 42 #define wdt_read(wdt, field) \
 43         __raw_readl((wdt)->base + (field))
 44 #define wdt_write(wtd, field, val) \
 45         __raw_writel((val), (wdt)->base + (field))
 46 
 47 /* AT91SAM9 watchdog runs a 12bit counter @ 256Hz,
 48  * use this to convert a watchdog
 49  * value from/to milliseconds.
 50  */
 51 #define ticks_to_hz_rounddown(t)        ((((t) + 1) * HZ) >> 8)
 52 #define ticks_to_hz_roundup(t)          (((((t) + 1) * HZ) + 255) >> 8)
 53 #define ticks_to_secs(t)                (((t) + 1) >> 8)
 54 #define secs_to_ticks(s)                ((s) ? (((s) << 8) - 1) : 0)
 55 
 56 #define WDT_MR_RESET    0x3FFF2FFF
 57 
 58 /* Watchdog max counter value in ticks */
 59 #define WDT_COUNTER_MAX_TICKS   0xFFF
 60 
 61 /* Watchdog max delta/value in secs */
 62 #define WDT_COUNTER_MAX_SECS    ticks_to_secs(WDT_COUNTER_MAX_TICKS)
 63 
 64 /* Hardware timeout in seconds */
 65 #define WDT_HW_TIMEOUT 2
 66 
 67 /* Timer heartbeat (500ms) */
 68 #define WDT_TIMEOUT     (HZ/2)
 69 
 70 /* User land timeout */
 71 #define WDT_HEARTBEAT 15
 72 static int heartbeat;
 73 module_param(heartbeat, int, 0);
 74 MODULE_PARM_DESC(heartbeat, "Watchdog heartbeats in seconds. "
 75         "(default = " __MODULE_STRING(WDT_HEARTBEAT) ")");
 76 
 77 static bool nowayout = WATCHDOG_NOWAYOUT;
 78 module_param(nowayout, bool, 0);
 79 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started "
 80         "(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
 81 
 82 #define to_wdt(wdd) container_of(wdd, struct at91wdt, wdd)
 83 struct at91wdt {
 84         struct watchdog_device wdd;
 85         void __iomem *base;
 86         unsigned long next_heartbeat;   /* the next_heartbeat for the timer */
 87         struct timer_list timer;        /* The timer that pings the watchdog */
 88         u32 mr;
 89         u32 mr_mask;
 90         unsigned long heartbeat;        /* WDT heartbeat in jiffies */
 91         bool nowayout;
 92         unsigned int irq;
 93 };
 94 
 95 /* ......................................................................... */
 96 
 97 static irqreturn_t wdt_interrupt(int irq, void *dev_id)
 98 {
 99         struct at91wdt *wdt = (struct at91wdt *)dev_id;
100 
101         if (wdt_read(wdt, AT91_WDT_SR)) {
102                 pr_crit("at91sam9 WDT software reset\n");
103                 emergency_restart();
104                 pr_crit("Reboot didn't ?????\n");
105         }
106 
107         return IRQ_HANDLED;
108 }
109 
110 /*
111  * Reload the watchdog timer.  (ie, pat the watchdog)
112  */
113 static inline void at91_wdt_reset(struct at91wdt *wdt)
114 {
115         wdt_write(wdt, AT91_WDT_CR, AT91_WDT_KEY | AT91_WDT_WDRSTT);
116 }
117 
118 /*
119  * Timer tick
120  */
121 static void at91_ping(unsigned long data)
122 {
123         struct at91wdt *wdt = (struct at91wdt *)data;
124         if (time_before(jiffies, wdt->next_heartbeat) ||
125             !watchdog_active(&wdt->wdd)) {
126                 at91_wdt_reset(wdt);
127                 mod_timer(&wdt->timer, jiffies + wdt->heartbeat);
128         } else {
129                 pr_crit("I will reset your machine !\n");
130         }
131 }
132 
133 static int at91_wdt_start(struct watchdog_device *wdd)
134 {
135         struct at91wdt *wdt = to_wdt(wdd);
136         /* calculate when the next userspace timeout will be */
137         wdt->next_heartbeat = jiffies + wdd->timeout * HZ;
138         return 0;
139 }
140 
141 static int at91_wdt_stop(struct watchdog_device *wdd)
142 {
143         /* The watchdog timer hardware can not be stopped... */
144         return 0;
145 }
146 
147 static int at91_wdt_set_timeout(struct watchdog_device *wdd, unsigned int new_timeout)
148 {
149         wdd->timeout = new_timeout;
150         return at91_wdt_start(wdd);
151 }
152 
153 static int at91_wdt_init(struct platform_device *pdev, struct at91wdt *wdt)
154 {
155         u32 tmp;
156         u32 delta;
157         u32 value;
158         int err;
159         u32 mask = wdt->mr_mask;
160         unsigned long min_heartbeat = 1;
161         unsigned long max_heartbeat;
162         struct device *dev = &pdev->dev;
163 
164         tmp = wdt_read(wdt, AT91_WDT_MR);
165         if ((tmp & mask) != (wdt->mr & mask)) {
166                 if (tmp == WDT_MR_RESET) {
167                         wdt_write(wdt, AT91_WDT_MR, wdt->mr);
168                         tmp = wdt_read(wdt, AT91_WDT_MR);
169                 }
170         }
171 
172         if (tmp & AT91_WDT_WDDIS) {
173                 if (wdt->mr & AT91_WDT_WDDIS)
174                         return 0;
175                 dev_err(dev, "watchdog is disabled\n");
176                 return -EINVAL;
177         }
178 
179         value = tmp & AT91_WDT_WDV;
180         delta = (tmp & AT91_WDT_WDD) >> 16;
181 
182         if (delta < value)
183                 min_heartbeat = ticks_to_hz_roundup(value - delta);
184 
185         max_heartbeat = ticks_to_hz_rounddown(value);
186         if (!max_heartbeat) {
187                 dev_err(dev,
188                         "heartbeat is too small for the system to handle it correctly\n");
189                 return -EINVAL;
190         }
191 
192         /*
193          * Try to reset the watchdog counter 4 or 2 times more often than
194          * actually requested, to avoid spurious watchdog reset.
195          * If this is not possible because of the min_heartbeat value, reset
196          * it at the min_heartbeat period.
197          */
198         if ((max_heartbeat / 4) >= min_heartbeat)
199                 wdt->heartbeat = max_heartbeat / 4;
200         else if ((max_heartbeat / 2) >= min_heartbeat)
201                 wdt->heartbeat = max_heartbeat / 2;
202         else
203                 wdt->heartbeat = min_heartbeat;
204 
205         if (max_heartbeat < min_heartbeat + 4)
206                 dev_warn(dev,
207                          "min heartbeat and max heartbeat might be too close for the system to handle it correctly\n");
208 
209         if ((tmp & AT91_WDT_WDFIEN) && wdt->irq) {
210                 err = request_irq(wdt->irq, wdt_interrupt,
211                                   IRQF_SHARED | IRQF_IRQPOLL |
212                                   IRQF_NO_SUSPEND,
213                                   pdev->name, wdt);
214                 if (err)
215                         return err;
216         }
217 
218         if ((tmp & wdt->mr_mask) != (wdt->mr & wdt->mr_mask))
219                 dev_warn(dev,
220                          "watchdog already configured differently (mr = %x expecting %x)\n",
221                          tmp & wdt->mr_mask, wdt->mr & wdt->mr_mask);
222 
223         setup_timer(&wdt->timer, at91_ping, (unsigned long)wdt);
224 
225         /*
226          * Use min_heartbeat the first time to avoid spurious watchdog reset:
227          * we don't know for how long the watchdog counter is running, and
228          *  - resetting it right now might trigger a watchdog fault reset
229          *  - waiting for heartbeat time might lead to a watchdog timeout
230          *    reset
231          */
232         mod_timer(&wdt->timer, jiffies + min_heartbeat);
233 
234         /* Try to set timeout from device tree first */
235         if (watchdog_init_timeout(&wdt->wdd, 0, dev))
236                 watchdog_init_timeout(&wdt->wdd, heartbeat, dev);
237         watchdog_set_nowayout(&wdt->wdd, wdt->nowayout);
238         err = watchdog_register_device(&wdt->wdd);
239         if (err)
240                 goto out_stop_timer;
241 
242         wdt->next_heartbeat = jiffies + wdt->wdd.timeout * HZ;
243 
244         return 0;
245 
246 out_stop_timer:
247         del_timer(&wdt->timer);
248         return err;
249 }
250 
251 /* ......................................................................... */
252 
253 static const struct watchdog_info at91_wdt_info = {
254         .identity       = DRV_NAME,
255         .options        = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING |
256                                                 WDIOF_MAGICCLOSE,
257 };
258 
259 static const struct watchdog_ops at91_wdt_ops = {
260         .owner =        THIS_MODULE,
261         .start =        at91_wdt_start,
262         .stop =         at91_wdt_stop,
263         .set_timeout =  at91_wdt_set_timeout,
264 };
265 
266 #if defined(CONFIG_OF)
267 static int of_at91wdt_init(struct device_node *np, struct at91wdt *wdt)
268 {
269         u32 min = 0;
270         u32 max = WDT_COUNTER_MAX_SECS;
271         const char *tmp;
272 
273         /* Get the interrupts property */
274         wdt->irq = irq_of_parse_and_map(np, 0);
275         if (!wdt->irq)
276                 dev_warn(wdt->wdd.parent, "failed to get IRQ from DT\n");
277 
278         if (!of_property_read_u32_index(np, "atmel,max-heartbeat-sec", 0,
279                                         &max)) {
280                 if (!max || max > WDT_COUNTER_MAX_SECS)
281                         max = WDT_COUNTER_MAX_SECS;
282 
283                 if (!of_property_read_u32_index(np, "atmel,min-heartbeat-sec",
284                                                 0, &min)) {
285                         if (min >= max)
286                                 min = max - 1;
287                 }
288         }
289 
290         min = secs_to_ticks(min);
291         max = secs_to_ticks(max);
292 
293         wdt->mr_mask = 0x3FFFFFFF;
294         wdt->mr = 0;
295         if (!of_property_read_string(np, "atmel,watchdog-type", &tmp) &&
296             !strcmp(tmp, "software")) {
297                 wdt->mr |= AT91_WDT_WDFIEN;
298                 wdt->mr_mask &= ~AT91_WDT_WDRPROC;
299         } else {
300                 wdt->mr |= AT91_WDT_WDRSTEN;
301         }
302 
303         if (!of_property_read_string(np, "atmel,reset-type", &tmp) &&
304             !strcmp(tmp, "proc"))
305                 wdt->mr |= AT91_WDT_WDRPROC;
306 
307         if (of_property_read_bool(np, "atmel,disable")) {
308                 wdt->mr |= AT91_WDT_WDDIS;
309                 wdt->mr_mask &= AT91_WDT_WDDIS;
310         }
311 
312         if (of_property_read_bool(np, "atmel,idle-halt"))
313                 wdt->mr |= AT91_WDT_WDIDLEHLT;
314 
315         if (of_property_read_bool(np, "atmel,dbg-halt"))
316                 wdt->mr |= AT91_WDT_WDDBGHLT;
317 
318         wdt->mr |= max | ((max - min) << 16);
319 
320         return 0;
321 }
322 #else
323 static inline int of_at91wdt_init(struct device_node *np, struct at91wdt *wdt)
324 {
325         return 0;
326 }
327 #endif
328 
329 static int __init at91wdt_probe(struct platform_device *pdev)
330 {
331         struct resource *r;
332         int err;
333         struct at91wdt *wdt;
334 
335         wdt = devm_kzalloc(&pdev->dev, sizeof(*wdt), GFP_KERNEL);
336         if (!wdt)
337                 return -ENOMEM;
338 
339         wdt->mr = (WDT_HW_TIMEOUT * 256) | AT91_WDT_WDRSTEN | AT91_WDT_WDD |
340                   AT91_WDT_WDDBGHLT | AT91_WDT_WDIDLEHLT;
341         wdt->mr_mask = 0x3FFFFFFF;
342         wdt->nowayout = nowayout;
343         wdt->wdd.parent = &pdev->dev;
344         wdt->wdd.info = &at91_wdt_info;
345         wdt->wdd.ops = &at91_wdt_ops;
346         wdt->wdd.timeout = WDT_HEARTBEAT;
347         wdt->wdd.min_timeout = 1;
348         wdt->wdd.max_timeout = 0xFFFF;
349 
350         r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
351         wdt->base = devm_ioremap_resource(&pdev->dev, r);
352         if (IS_ERR(wdt->base))
353                 return PTR_ERR(wdt->base);
354 
355         if (pdev->dev.of_node) {
356                 err = of_at91wdt_init(pdev->dev.of_node, wdt);
357                 if (err)
358                         return err;
359         }
360 
361         err = at91_wdt_init(pdev, wdt);
362         if (err)
363                 return err;
364 
365         platform_set_drvdata(pdev, wdt);
366 
367         pr_info("enabled (heartbeat=%d sec, nowayout=%d)\n",
368                 wdt->wdd.timeout, wdt->nowayout);
369 
370         return 0;
371 }
372 
373 static int __exit at91wdt_remove(struct platform_device *pdev)
374 {
375         struct at91wdt *wdt = platform_get_drvdata(pdev);
376         watchdog_unregister_device(&wdt->wdd);
377 
378         pr_warn("I quit now, hardware will probably reboot!\n");
379         del_timer(&wdt->timer);
380 
381         return 0;
382 }
383 
384 #if defined(CONFIG_OF)
385 static const struct of_device_id at91_wdt_dt_ids[] = {
386         { .compatible = "atmel,at91sam9260-wdt" },
387         { /* sentinel */ }
388 };
389 
390 MODULE_DEVICE_TABLE(of, at91_wdt_dt_ids);
391 #endif
392 
393 static struct platform_driver at91wdt_driver = {
394         .remove         = __exit_p(at91wdt_remove),
395         .driver         = {
396                 .name   = "at91_wdt",
397                 .of_match_table = of_match_ptr(at91_wdt_dt_ids),
398         },
399 };
400 
401 module_platform_driver_probe(at91wdt_driver, at91wdt_probe);
402 
403 MODULE_AUTHOR("Renaud CERRATO <r.cerrato@til-technologies.fr>");
404 MODULE_DESCRIPTION("Watchdog driver for Atmel AT91SAM9x processors");
405 MODULE_LICENSE("GPL");
406 

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