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Linux/drivers/watchdog/imx2_wdt.c

  1 /*
  2  * Watchdog driver for IMX2 and later processors
  3  *
  4  *  Copyright (C) 2010 Wolfram Sang, Pengutronix e.K. <w.sang@pengutronix.de>
  5  *  Copyright (C) 2014 Freescale Semiconductor, Inc.
  6  *
  7  * some parts adapted by similar drivers from Darius Augulis and Vladimir
  8  * Zapolskiy, additional improvements by Wim Van Sebroeck.
  9  *
 10  * This program is free software; you can redistribute it and/or modify it
 11  * under the terms of the GNU General Public License version 2 as published by
 12  * the Free Software Foundation.
 13  *
 14  * NOTE: MX1 has a slightly different Watchdog than MX2 and later:
 15  *
 16  *                      MX1:            MX2+:
 17  *                      ----            -----
 18  * Registers:           32-bit          16-bit
 19  * Stopable timer:      Yes             No
 20  * Need to enable clk:  No              Yes
 21  * Halt on suspend:     Manual          Can be automatic
 22  */
 23 
 24 #include <linux/clk.h>
 25 #include <linux/delay.h>
 26 #include <linux/init.h>
 27 #include <linux/io.h>
 28 #include <linux/jiffies.h>
 29 #include <linux/kernel.h>
 30 #include <linux/module.h>
 31 #include <linux/moduleparam.h>
 32 #include <linux/notifier.h>
 33 #include <linux/of_address.h>
 34 #include <linux/platform_device.h>
 35 #include <linux/reboot.h>
 36 #include <linux/regmap.h>
 37 #include <linux/timer.h>
 38 #include <linux/watchdog.h>
 39 
 40 #define DRIVER_NAME "imx2-wdt"
 41 
 42 #define IMX2_WDT_WCR            0x00            /* Control Register */
 43 #define IMX2_WDT_WCR_WT         (0xFF << 8)     /* -> Watchdog Timeout Field */
 44 #define IMX2_WDT_WCR_WRE        (1 << 3)        /* -> WDOG Reset Enable */
 45 #define IMX2_WDT_WCR_WDE        (1 << 2)        /* -> Watchdog Enable */
 46 #define IMX2_WDT_WCR_WDZST      (1 << 0)        /* -> Watchdog timer Suspend */
 47 
 48 #define IMX2_WDT_WSR            0x02            /* Service Register */
 49 #define IMX2_WDT_SEQ1           0x5555          /* -> service sequence 1 */
 50 #define IMX2_WDT_SEQ2           0xAAAA          /* -> service sequence 2 */
 51 
 52 #define IMX2_WDT_WRSR           0x04            /* Reset Status Register */
 53 #define IMX2_WDT_WRSR_TOUT      (1 << 1)        /* -> Reset due to Timeout */
 54 
 55 #define IMX2_WDT_WMCR           0x08            /* Misc Register */
 56 
 57 #define IMX2_WDT_MAX_TIME       128
 58 #define IMX2_WDT_DEFAULT_TIME   60              /* in seconds */
 59 
 60 #define WDOG_SEC_TO_COUNT(s)    ((s * 2 - 1) << 8)
 61 
 62 struct imx2_wdt_device {
 63         struct clk *clk;
 64         struct regmap *regmap;
 65         struct timer_list timer;        /* Pings the watchdog when closed */
 66         struct watchdog_device wdog;
 67         struct notifier_block restart_handler;
 68 };
 69 
 70 static bool nowayout = WATCHDOG_NOWAYOUT;
 71 module_param(nowayout, bool, 0);
 72 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
 73                                 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
 74 
 75 
 76 static unsigned timeout = IMX2_WDT_DEFAULT_TIME;
 77 module_param(timeout, uint, 0);
 78 MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds (default="
 79                                 __MODULE_STRING(IMX2_WDT_DEFAULT_TIME) ")");
 80 
 81 static const struct watchdog_info imx2_wdt_info = {
 82         .identity = "imx2+ watchdog",
 83         .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE,
 84 };
 85 
 86 static int imx2_restart_handler(struct notifier_block *this, unsigned long mode,
 87                                 void *cmd)
 88 {
 89         unsigned int wcr_enable = IMX2_WDT_WCR_WDE;
 90         struct imx2_wdt_device *wdev = container_of(this,
 91                                                     struct imx2_wdt_device,
 92                                                     restart_handler);
 93         /* Assert SRS signal */
 94         regmap_write(wdev->regmap, IMX2_WDT_WCR, wcr_enable);
 95         /*
 96          * Due to imx6q errata ERR004346 (WDOG: WDOG SRS bit requires to be
 97          * written twice), we add another two writes to ensure there must be at
 98          * least two writes happen in the same one 32kHz clock period.  We save
 99          * the target check here, since the writes shouldn't be a huge burden
100          * for other platforms.
101          */
102         regmap_write(wdev->regmap, IMX2_WDT_WCR, wcr_enable);
103         regmap_write(wdev->regmap, IMX2_WDT_WCR, wcr_enable);
104 
105         /* wait for reset to assert... */
106         mdelay(500);
107 
108         return NOTIFY_DONE;
109 }
110 
111 static inline void imx2_wdt_setup(struct watchdog_device *wdog)
112 {
113         struct imx2_wdt_device *wdev = watchdog_get_drvdata(wdog);
114         u32 val;
115 
116         regmap_read(wdev->regmap, IMX2_WDT_WCR, &val);
117 
118         /* Suspend timer in low power mode, write once-only */
119         val |= IMX2_WDT_WCR_WDZST;
120         /* Strip the old watchdog Time-Out value */
121         val &= ~IMX2_WDT_WCR_WT;
122         /* Generate reset if WDOG times out */
123         val &= ~IMX2_WDT_WCR_WRE;
124         /* Keep Watchdog Disabled */
125         val &= ~IMX2_WDT_WCR_WDE;
126         /* Set the watchdog's Time-Out value */
127         val |= WDOG_SEC_TO_COUNT(wdog->timeout);
128 
129         regmap_write(wdev->regmap, IMX2_WDT_WCR, val);
130 
131         /* enable the watchdog */
132         val |= IMX2_WDT_WCR_WDE;
133         regmap_write(wdev->regmap, IMX2_WDT_WCR, val);
134 }
135 
136 static inline bool imx2_wdt_is_running(struct imx2_wdt_device *wdev)
137 {
138         u32 val;
139 
140         regmap_read(wdev->regmap, IMX2_WDT_WCR, &val);
141 
142         return val & IMX2_WDT_WCR_WDE;
143 }
144 
145 static int imx2_wdt_ping(struct watchdog_device *wdog)
146 {
147         struct imx2_wdt_device *wdev = watchdog_get_drvdata(wdog);
148 
149         regmap_write(wdev->regmap, IMX2_WDT_WSR, IMX2_WDT_SEQ1);
150         regmap_write(wdev->regmap, IMX2_WDT_WSR, IMX2_WDT_SEQ2);
151         return 0;
152 }
153 
154 static void imx2_wdt_timer_ping(unsigned long arg)
155 {
156         struct watchdog_device *wdog = (struct watchdog_device *)arg;
157         struct imx2_wdt_device *wdev = watchdog_get_drvdata(wdog);
158 
159         /* ping it every wdog->timeout / 2 seconds to prevent reboot */
160         imx2_wdt_ping(wdog);
161         mod_timer(&wdev->timer, jiffies + wdog->timeout * HZ / 2);
162 }
163 
164 static int imx2_wdt_set_timeout(struct watchdog_device *wdog,
165                                 unsigned int new_timeout)
166 {
167         struct imx2_wdt_device *wdev = watchdog_get_drvdata(wdog);
168 
169         wdog->timeout = new_timeout;
170 
171         regmap_update_bits(wdev->regmap, IMX2_WDT_WCR, IMX2_WDT_WCR_WT,
172                            WDOG_SEC_TO_COUNT(new_timeout));
173         return 0;
174 }
175 
176 static int imx2_wdt_start(struct watchdog_device *wdog)
177 {
178         struct imx2_wdt_device *wdev = watchdog_get_drvdata(wdog);
179 
180         if (imx2_wdt_is_running(wdev)) {
181                 /* delete the timer that pings the watchdog after close */
182                 del_timer_sync(&wdev->timer);
183                 imx2_wdt_set_timeout(wdog, wdog->timeout);
184         } else
185                 imx2_wdt_setup(wdog);
186 
187         return imx2_wdt_ping(wdog);
188 }
189 
190 static int imx2_wdt_stop(struct watchdog_device *wdog)
191 {
192         /*
193          * We don't need a clk_disable, it cannot be disabled once started.
194          * We use a timer to ping the watchdog while /dev/watchdog is closed
195          */
196         imx2_wdt_timer_ping((unsigned long)wdog);
197         return 0;
198 }
199 
200 static inline void imx2_wdt_ping_if_active(struct watchdog_device *wdog)
201 {
202         struct imx2_wdt_device *wdev = watchdog_get_drvdata(wdog);
203 
204         if (imx2_wdt_is_running(wdev)) {
205                 imx2_wdt_set_timeout(wdog, wdog->timeout);
206                 imx2_wdt_timer_ping((unsigned long)wdog);
207         }
208 }
209 
210 static const struct watchdog_ops imx2_wdt_ops = {
211         .owner = THIS_MODULE,
212         .start = imx2_wdt_start,
213         .stop = imx2_wdt_stop,
214         .ping = imx2_wdt_ping,
215         .set_timeout = imx2_wdt_set_timeout,
216 };
217 
218 static const struct regmap_config imx2_wdt_regmap_config = {
219         .reg_bits = 16,
220         .reg_stride = 2,
221         .val_bits = 16,
222         .max_register = 0x8,
223 };
224 
225 static int __init imx2_wdt_probe(struct platform_device *pdev)
226 {
227         struct imx2_wdt_device *wdev;
228         struct watchdog_device *wdog;
229         struct resource *res;
230         void __iomem *base;
231         int ret;
232         u32 val;
233 
234         wdev = devm_kzalloc(&pdev->dev, sizeof(*wdev), GFP_KERNEL);
235         if (!wdev)
236                 return -ENOMEM;
237 
238         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
239         base = devm_ioremap_resource(&pdev->dev, res);
240         if (IS_ERR(base))
241                 return PTR_ERR(base);
242 
243         wdev->regmap = devm_regmap_init_mmio_clk(&pdev->dev, NULL, base,
244                                                  &imx2_wdt_regmap_config);
245         if (IS_ERR(wdev->regmap)) {
246                 dev_err(&pdev->dev, "regmap init failed\n");
247                 return PTR_ERR(wdev->regmap);
248         }
249 
250         wdev->clk = devm_clk_get(&pdev->dev, NULL);
251         if (IS_ERR(wdev->clk)) {
252                 dev_err(&pdev->dev, "can't get Watchdog clock\n");
253                 return PTR_ERR(wdev->clk);
254         }
255 
256         wdog                    = &wdev->wdog;
257         wdog->info              = &imx2_wdt_info;
258         wdog->ops               = &imx2_wdt_ops;
259         wdog->min_timeout       = 1;
260         wdog->max_timeout       = IMX2_WDT_MAX_TIME;
261         wdog->parent            = &pdev->dev;
262 
263         ret = clk_prepare_enable(wdev->clk);
264         if (ret)
265                 return ret;
266 
267         regmap_read(wdev->regmap, IMX2_WDT_WRSR, &val);
268         wdog->bootstatus = val & IMX2_WDT_WRSR_TOUT ? WDIOF_CARDRESET : 0;
269 
270         wdog->timeout = clamp_t(unsigned, timeout, 1, IMX2_WDT_MAX_TIME);
271         if (wdog->timeout != timeout)
272                 dev_warn(&pdev->dev, "Initial timeout out of range! Clamped from %u to %u\n",
273                          timeout, wdog->timeout);
274 
275         platform_set_drvdata(pdev, wdog);
276         watchdog_set_drvdata(wdog, wdev);
277         watchdog_set_nowayout(wdog, nowayout);
278         watchdog_init_timeout(wdog, timeout, &pdev->dev);
279 
280         setup_timer(&wdev->timer, imx2_wdt_timer_ping, (unsigned long)wdog);
281 
282         imx2_wdt_ping_if_active(wdog);
283 
284         /*
285          * Disable the watchdog power down counter at boot. Otherwise the power
286          * down counter will pull down the #WDOG interrupt line for one clock
287          * cycle.
288          */
289         regmap_write(wdev->regmap, IMX2_WDT_WMCR, 0);
290 
291         ret = watchdog_register_device(wdog);
292         if (ret) {
293                 dev_err(&pdev->dev, "cannot register watchdog device\n");
294                 goto disable_clk;
295         }
296 
297         wdev->restart_handler.notifier_call = imx2_restart_handler;
298         wdev->restart_handler.priority = 128;
299         ret = register_restart_handler(&wdev->restart_handler);
300         if (ret)
301                 dev_err(&pdev->dev, "cannot register restart handler\n");
302 
303         dev_info(&pdev->dev, "timeout %d sec (nowayout=%d)\n",
304                  wdog->timeout, nowayout);
305 
306         return 0;
307 
308 disable_clk:
309         clk_disable_unprepare(wdev->clk);
310         return ret;
311 }
312 
313 static int __exit imx2_wdt_remove(struct platform_device *pdev)
314 {
315         struct watchdog_device *wdog = platform_get_drvdata(pdev);
316         struct imx2_wdt_device *wdev = watchdog_get_drvdata(wdog);
317 
318         unregister_restart_handler(&wdev->restart_handler);
319 
320         watchdog_unregister_device(wdog);
321 
322         if (imx2_wdt_is_running(wdev)) {
323                 del_timer_sync(&wdev->timer);
324                 imx2_wdt_ping(wdog);
325                 dev_crit(&pdev->dev, "Device removed: Expect reboot!\n");
326         }
327         return 0;
328 }
329 
330 static void imx2_wdt_shutdown(struct platform_device *pdev)
331 {
332         struct watchdog_device *wdog = platform_get_drvdata(pdev);
333         struct imx2_wdt_device *wdev = watchdog_get_drvdata(wdog);
334 
335         if (imx2_wdt_is_running(wdev)) {
336                 /*
337                  * We are running, we need to delete the timer but will
338                  * give max timeout before reboot will take place
339                  */
340                 del_timer_sync(&wdev->timer);
341                 imx2_wdt_set_timeout(wdog, IMX2_WDT_MAX_TIME);
342                 imx2_wdt_ping(wdog);
343                 dev_crit(&pdev->dev, "Device shutdown: Expect reboot!\n");
344         }
345 }
346 
347 #ifdef CONFIG_PM_SLEEP
348 /* Disable watchdog if it is active or non-active but still running */
349 static int imx2_wdt_suspend(struct device *dev)
350 {
351         struct watchdog_device *wdog = dev_get_drvdata(dev);
352         struct imx2_wdt_device *wdev = watchdog_get_drvdata(wdog);
353 
354         /* The watchdog IP block is running */
355         if (imx2_wdt_is_running(wdev)) {
356                 imx2_wdt_set_timeout(wdog, IMX2_WDT_MAX_TIME);
357                 imx2_wdt_ping(wdog);
358 
359                 /* The watchdog is not active */
360                 if (!watchdog_active(wdog))
361                         del_timer_sync(&wdev->timer);
362         }
363 
364         clk_disable_unprepare(wdev->clk);
365 
366         return 0;
367 }
368 
369 /* Enable watchdog and configure it if necessary */
370 static int imx2_wdt_resume(struct device *dev)
371 {
372         struct watchdog_device *wdog = dev_get_drvdata(dev);
373         struct imx2_wdt_device *wdev = watchdog_get_drvdata(wdog);
374         int ret;
375 
376         ret = clk_prepare_enable(wdev->clk);
377         if (ret)
378                 return ret;
379 
380         if (watchdog_active(wdog) && !imx2_wdt_is_running(wdev)) {
381                 /*
382                  * If the watchdog is still active and resumes
383                  * from deep sleep state, need to restart the
384                  * watchdog again.
385                  */
386                 imx2_wdt_setup(wdog);
387                 imx2_wdt_set_timeout(wdog, wdog->timeout);
388                 imx2_wdt_ping(wdog);
389         } else if (imx2_wdt_is_running(wdev)) {
390                 /* Resuming from non-deep sleep state. */
391                 imx2_wdt_set_timeout(wdog, wdog->timeout);
392                 imx2_wdt_ping(wdog);
393                 /*
394                  * But the watchdog is not active, then start
395                  * the timer again.
396                  */
397                 if (!watchdog_active(wdog))
398                         mod_timer(&wdev->timer,
399                                   jiffies + wdog->timeout * HZ / 2);
400         }
401 
402         return 0;
403 }
404 #endif
405 
406 static SIMPLE_DEV_PM_OPS(imx2_wdt_pm_ops, imx2_wdt_suspend,
407                          imx2_wdt_resume);
408 
409 static const struct of_device_id imx2_wdt_dt_ids[] = {
410         { .compatible = "fsl,imx21-wdt", },
411         { /* sentinel */ }
412 };
413 MODULE_DEVICE_TABLE(of, imx2_wdt_dt_ids);
414 
415 static struct platform_driver imx2_wdt_driver = {
416         .remove         = __exit_p(imx2_wdt_remove),
417         .shutdown       = imx2_wdt_shutdown,
418         .driver         = {
419                 .name   = DRIVER_NAME,
420                 .pm     = &imx2_wdt_pm_ops,
421                 .of_match_table = imx2_wdt_dt_ids,
422         },
423 };
424 
425 module_platform_driver_probe(imx2_wdt_driver, imx2_wdt_probe);
426 
427 MODULE_AUTHOR("Wolfram Sang");
428 MODULE_DESCRIPTION("Watchdog driver for IMX2 and later");
429 MODULE_LICENSE("GPL v2");
430 MODULE_ALIAS("platform:" DRIVER_NAME);
431 

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