Version:  2.0.40 2.2.26 2.4.37 2.6.39 3.0 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 3.9 3.10 3.11 3.12 3.13 3.14 3.15

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/init.h>
 25 #include <linux/kernel.h>
 26 #include <linux/miscdevice.h>
 27 #include <linux/module.h>
 28 #include <linux/moduleparam.h>
 29 #include <linux/platform_device.h>
 30 #include <linux/watchdog.h>
 31 #include <linux/clk.h>
 32 #include <linux/fs.h>
 33 #include <linux/io.h>
 34 #include <linux/uaccess.h>
 35 #include <linux/timer.h>
 36 #include <linux/jiffies.h>
 37 
 38 #define DRIVER_NAME "imx2-wdt"
 39 
 40 #define IMX2_WDT_WCR            0x00            /* Control Register */
 41 #define IMX2_WDT_WCR_WT         (0xFF << 8)     /* -> Watchdog Timeout Field */
 42 #define IMX2_WDT_WCR_WRE        (1 << 3)        /* -> WDOG Reset Enable */
 43 #define IMX2_WDT_WCR_WDE        (1 << 2)        /* -> Watchdog Enable */
 44 #define IMX2_WDT_WCR_WDZST      (1 << 0)        /* -> Watchdog timer Suspend */
 45 
 46 #define IMX2_WDT_WSR            0x02            /* Service Register */
 47 #define IMX2_WDT_SEQ1           0x5555          /* -> service sequence 1 */
 48 #define IMX2_WDT_SEQ2           0xAAAA          /* -> service sequence 2 */
 49 
 50 #define IMX2_WDT_WRSR           0x04            /* Reset Status Register */
 51 #define IMX2_WDT_WRSR_TOUT      (1 << 1)        /* -> Reset due to Timeout */
 52 
 53 #define IMX2_WDT_MAX_TIME       128
 54 #define IMX2_WDT_DEFAULT_TIME   60              /* in seconds */
 55 
 56 #define WDOG_SEC_TO_COUNT(s)    ((s * 2 - 1) << 8)
 57 
 58 #define IMX2_WDT_STATUS_OPEN    0
 59 #define IMX2_WDT_STATUS_STARTED 1
 60 #define IMX2_WDT_EXPECT_CLOSE   2
 61 
 62 static struct {
 63         struct clk *clk;
 64         void __iomem *base;
 65         unsigned timeout;
 66         unsigned long status;
 67         struct timer_list timer;        /* Pings the watchdog when closed */
 68 } imx2_wdt;
 69 
 70 static struct miscdevice imx2_wdt_miscdev;
 71 
 72 static bool nowayout = WATCHDOG_NOWAYOUT;
 73 module_param(nowayout, bool, 0);
 74 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
 75                                 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
 76 
 77 
 78 static unsigned timeout = IMX2_WDT_DEFAULT_TIME;
 79 module_param(timeout, uint, 0);
 80 MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds (default="
 81                                 __MODULE_STRING(IMX2_WDT_DEFAULT_TIME) ")");
 82 
 83 static const struct watchdog_info imx2_wdt_info = {
 84         .identity = "imx2+ watchdog",
 85         .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE,
 86 };
 87 
 88 static inline void imx2_wdt_setup(void)
 89 {
 90         u16 val = __raw_readw(imx2_wdt.base + IMX2_WDT_WCR);
 91 
 92         /* Suspend timer in low power mode, write once-only */
 93         val |= IMX2_WDT_WCR_WDZST;
 94         /* Strip the old watchdog Time-Out value */
 95         val &= ~IMX2_WDT_WCR_WT;
 96         /* Generate reset if WDOG times out */
 97         val &= ~IMX2_WDT_WCR_WRE;
 98         /* Keep Watchdog Disabled */
 99         val &= ~IMX2_WDT_WCR_WDE;
100         /* Set the watchdog's Time-Out value */
101         val |= WDOG_SEC_TO_COUNT(imx2_wdt.timeout);
102 
103         __raw_writew(val, imx2_wdt.base + IMX2_WDT_WCR);
104 
105         /* enable the watchdog */
106         val |= IMX2_WDT_WCR_WDE;
107         __raw_writew(val, imx2_wdt.base + IMX2_WDT_WCR);
108 }
109 
110 static inline void imx2_wdt_ping(void)
111 {
112         __raw_writew(IMX2_WDT_SEQ1, imx2_wdt.base + IMX2_WDT_WSR);
113         __raw_writew(IMX2_WDT_SEQ2, imx2_wdt.base + IMX2_WDT_WSR);
114 }
115 
116 static void imx2_wdt_timer_ping(unsigned long arg)
117 {
118         /* ping it every imx2_wdt.timeout / 2 seconds to prevent reboot */
119         imx2_wdt_ping();
120         mod_timer(&imx2_wdt.timer, jiffies + imx2_wdt.timeout * HZ / 2);
121 }
122 
123 static void imx2_wdt_start(void)
124 {
125         if (!test_and_set_bit(IMX2_WDT_STATUS_STARTED, &imx2_wdt.status)) {
126                 /* at our first start we enable clock and do initialisations */
127                 clk_prepare_enable(imx2_wdt.clk);
128 
129                 imx2_wdt_setup();
130         } else  /* delete the timer that pings the watchdog after close */
131                 del_timer_sync(&imx2_wdt.timer);
132 
133         /* Watchdog is enabled - time to reload the timeout value */
134         imx2_wdt_ping();
135 }
136 
137 static void imx2_wdt_stop(void)
138 {
139         /* we don't need a clk_disable, it cannot be disabled once started.
140          * We use a timer to ping the watchdog while /dev/watchdog is closed */
141         imx2_wdt_timer_ping(0);
142 }
143 
144 static void imx2_wdt_set_timeout(int new_timeout)
145 {
146         u16 val = __raw_readw(imx2_wdt.base + IMX2_WDT_WCR);
147 
148         /* set the new timeout value in the WSR */
149         val &= ~IMX2_WDT_WCR_WT;
150         val |= WDOG_SEC_TO_COUNT(new_timeout);
151         __raw_writew(val, imx2_wdt.base + IMX2_WDT_WCR);
152 }
153 
154 static int imx2_wdt_open(struct inode *inode, struct file *file)
155 {
156         if (test_and_set_bit(IMX2_WDT_STATUS_OPEN, &imx2_wdt.status))
157                 return -EBUSY;
158 
159         imx2_wdt_start();
160         return nonseekable_open(inode, file);
161 }
162 
163 static int imx2_wdt_close(struct inode *inode, struct file *file)
164 {
165         if (test_bit(IMX2_WDT_EXPECT_CLOSE, &imx2_wdt.status) && !nowayout)
166                 imx2_wdt_stop();
167         else {
168                 dev_crit(imx2_wdt_miscdev.parent,
169                         "Unexpected close: Expect reboot!\n");
170                 imx2_wdt_ping();
171         }
172 
173         clear_bit(IMX2_WDT_EXPECT_CLOSE, &imx2_wdt.status);
174         clear_bit(IMX2_WDT_STATUS_OPEN, &imx2_wdt.status);
175         return 0;
176 }
177 
178 static long imx2_wdt_ioctl(struct file *file, unsigned int cmd,
179                                                         unsigned long arg)
180 {
181         void __user *argp = (void __user *)arg;
182         int __user *p = argp;
183         int new_value;
184         u16 val;
185 
186         switch (cmd) {
187         case WDIOC_GETSUPPORT:
188                 return copy_to_user(argp, &imx2_wdt_info,
189                         sizeof(struct watchdog_info)) ? -EFAULT : 0;
190 
191         case WDIOC_GETSTATUS:
192                 return put_user(0, p);
193 
194         case WDIOC_GETBOOTSTATUS:
195                 val = __raw_readw(imx2_wdt.base + IMX2_WDT_WRSR);
196                 new_value = val & IMX2_WDT_WRSR_TOUT ? WDIOF_CARDRESET : 0;
197                 return put_user(new_value, p);
198 
199         case WDIOC_KEEPALIVE:
200                 imx2_wdt_ping();
201                 return 0;
202 
203         case WDIOC_SETTIMEOUT:
204                 if (get_user(new_value, p))
205                         return -EFAULT;
206                 if ((new_value < 1) || (new_value > IMX2_WDT_MAX_TIME))
207                         return -EINVAL;
208                 imx2_wdt_set_timeout(new_value);
209                 imx2_wdt.timeout = new_value;
210                 imx2_wdt_ping();
211 
212                 /* Fallthrough to return current value */
213         case WDIOC_GETTIMEOUT:
214                 return put_user(imx2_wdt.timeout, p);
215 
216         default:
217                 return -ENOTTY;
218         }
219 }
220 
221 static ssize_t imx2_wdt_write(struct file *file, const char __user *data,
222                                                 size_t len, loff_t *ppos)
223 {
224         size_t i;
225         char c;
226 
227         if (len == 0)   /* Can we see this even ? */
228                 return 0;
229 
230         clear_bit(IMX2_WDT_EXPECT_CLOSE, &imx2_wdt.status);
231         /* scan to see whether or not we got the magic character */
232         for (i = 0; i != len; i++) {
233                 if (get_user(c, data + i))
234                         return -EFAULT;
235                 if (c == 'V')
236                         set_bit(IMX2_WDT_EXPECT_CLOSE, &imx2_wdt.status);
237         }
238 
239         imx2_wdt_ping();
240         return len;
241 }
242 
243 static const struct file_operations imx2_wdt_fops = {
244         .owner = THIS_MODULE,
245         .llseek = no_llseek,
246         .unlocked_ioctl = imx2_wdt_ioctl,
247         .open = imx2_wdt_open,
248         .release = imx2_wdt_close,
249         .write = imx2_wdt_write,
250 };
251 
252 static struct miscdevice imx2_wdt_miscdev = {
253         .minor = WATCHDOG_MINOR,
254         .name = "watchdog",
255         .fops = &imx2_wdt_fops,
256 };
257 
258 static int __init imx2_wdt_probe(struct platform_device *pdev)
259 {
260         int ret;
261         struct resource *res;
262 
263         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
264         imx2_wdt.base = devm_ioremap_resource(&pdev->dev, res);
265         if (IS_ERR(imx2_wdt.base))
266                 return PTR_ERR(imx2_wdt.base);
267 
268         imx2_wdt.clk = devm_clk_get(&pdev->dev, NULL);
269         if (IS_ERR(imx2_wdt.clk)) {
270                 dev_err(&pdev->dev, "can't get Watchdog clock\n");
271                 return PTR_ERR(imx2_wdt.clk);
272         }
273 
274         imx2_wdt.timeout = clamp_t(unsigned, timeout, 1, IMX2_WDT_MAX_TIME);
275         if (imx2_wdt.timeout != timeout)
276                 dev_warn(&pdev->dev, "Initial timeout out of range! "
277                         "Clamped from %u to %u\n", timeout, imx2_wdt.timeout);
278 
279         setup_timer(&imx2_wdt.timer, imx2_wdt_timer_ping, 0);
280 
281         imx2_wdt_miscdev.parent = &pdev->dev;
282         ret = misc_register(&imx2_wdt_miscdev);
283         if (ret)
284                 goto fail;
285 
286         dev_info(&pdev->dev,
287                 "IMX2+ Watchdog Timer enabled. timeout=%ds (nowayout=%d)\n",
288                                                 imx2_wdt.timeout, nowayout);
289         return 0;
290 
291 fail:
292         imx2_wdt_miscdev.parent = NULL;
293         return ret;
294 }
295 
296 static int __exit imx2_wdt_remove(struct platform_device *pdev)
297 {
298         misc_deregister(&imx2_wdt_miscdev);
299 
300         if (test_bit(IMX2_WDT_STATUS_STARTED, &imx2_wdt.status)) {
301                 del_timer_sync(&imx2_wdt.timer);
302 
303                 dev_crit(imx2_wdt_miscdev.parent,
304                         "Device removed: Expect reboot!\n");
305         }
306 
307         imx2_wdt_miscdev.parent = NULL;
308         return 0;
309 }
310 
311 static void imx2_wdt_shutdown(struct platform_device *pdev)
312 {
313         if (test_bit(IMX2_WDT_STATUS_STARTED, &imx2_wdt.status)) {
314                 /* we are running, we need to delete the timer but will give
315                  * max timeout before reboot will take place */
316                 del_timer_sync(&imx2_wdt.timer);
317                 imx2_wdt_set_timeout(IMX2_WDT_MAX_TIME);
318                 imx2_wdt_ping();
319 
320                 dev_crit(imx2_wdt_miscdev.parent,
321                         "Device shutdown: Expect reboot!\n");
322         }
323 }
324 
325 static const struct of_device_id imx2_wdt_dt_ids[] = {
326         { .compatible = "fsl,imx21-wdt", },
327         { /* sentinel */ }
328 };
329 MODULE_DEVICE_TABLE(of, imx2_wdt_dt_ids);
330 
331 static struct platform_driver imx2_wdt_driver = {
332         .remove         = __exit_p(imx2_wdt_remove),
333         .shutdown       = imx2_wdt_shutdown,
334         .driver         = {
335                 .name   = DRIVER_NAME,
336                 .owner  = THIS_MODULE,
337                 .of_match_table = imx2_wdt_dt_ids,
338         },
339 };
340 
341 module_platform_driver_probe(imx2_wdt_driver, imx2_wdt_probe);
342 
343 MODULE_AUTHOR("Wolfram Sang");
344 MODULE_DESCRIPTION("Watchdog driver for IMX2 and later");
345 MODULE_LICENSE("GPL v2");
346 MODULE_ALIAS("platform:" DRIVER_NAME);
347 

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