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Linux/drivers/watchdog/rc32434_wdt.c

  1 /*
  2  *  IDT Interprise 79RC32434 watchdog driver
  3  *
  4  *  Copyright (C) 2006, Ondrej Zajicek <santiago@crfreenet.org>
  5  *  Copyright (C) 2008, Florian Fainelli <florian@openwrt.org>
  6  *
  7  *  based on
  8  *  SoftDog 0.05:       A Software Watchdog Device
  9  *
 10  *  (c) Copyright 1996 Alan Cox <alan@lxorguk.ukuu.org.uk>,
 11  *                                      All Rights Reserved.
 12  *
 13  *  This program is free software; you can redistribute it and/or
 14  *  modify it under the terms of the GNU General Public License
 15  *  as published by the Free Software Foundation; either version
 16  *  2 of the License, or (at your option) any later version.
 17  *
 18  */
 19 
 20 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 21 
 22 #include <linux/module.h>               /* For module specific items */
 23 #include <linux/moduleparam.h>          /* For new moduleparam's */
 24 #include <linux/types.h>                /* For standard types (like size_t) */
 25 #include <linux/errno.h>                /* For the -ENODEV/... values */
 26 #include <linux/kernel.h>               /* For printk/panic/... */
 27 #include <linux/fs.h>                   /* For file operations */
 28 #include <linux/miscdevice.h>           /* For struct miscdevice */
 29 #include <linux/watchdog.h>             /* For the watchdog specific items */
 30 #include <linux/init.h>                 /* For __init/__exit/... */
 31 #include <linux/platform_device.h>      /* For platform_driver framework */
 32 #include <linux/spinlock.h>             /* For spin_lock/spin_unlock/... */
 33 #include <linux/uaccess.h>              /* For copy_to_user/put_user/... */
 34 #include <linux/io.h>                   /* For devm_ioremap_nocache */
 35 
 36 #include <asm/mach-rc32434/integ.h>     /* For the Watchdog registers */
 37 
 38 #define VERSION "1.0"
 39 
 40 static struct {
 41         unsigned long inuse;
 42         spinlock_t io_lock;
 43 } rc32434_wdt_device;
 44 
 45 static struct integ __iomem *wdt_reg;
 46 
 47 static int expect_close;
 48 
 49 /* Board internal clock speed in Hz,
 50  * the watchdog timer ticks at. */
 51 extern unsigned int idt_cpu_freq;
 52 
 53 /* translate wtcompare value to seconds and vice versa */
 54 #define WTCOMP2SEC(x)   (x / idt_cpu_freq)
 55 #define SEC2WTCOMP(x)   (x * idt_cpu_freq)
 56 
 57 /* Use a default timeout of 20s. This should be
 58  * safe for CPU clock speeds up to 400MHz, as
 59  * ((2 ^ 32) - 1) / (400MHz / 2) = 21s.  */
 60 #define WATCHDOG_TIMEOUT 20
 61 
 62 static int timeout = WATCHDOG_TIMEOUT;
 63 module_param(timeout, int, 0);
 64 MODULE_PARM_DESC(timeout, "Watchdog timeout value, in seconds (default="
 65                 __MODULE_STRING(WATCHDOG_TIMEOUT) ")");
 66 
 67 static bool nowayout = WATCHDOG_NOWAYOUT;
 68 module_param(nowayout, bool, 0);
 69 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
 70         __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
 71 
 72 /* apply or and nand masks to data read from addr and write back */
 73 #define SET_BITS(addr, or, nand) \
 74         writel((readl(&addr) | or) & ~nand, &addr)
 75 
 76 static int rc32434_wdt_set(int new_timeout)
 77 {
 78         int max_to = WTCOMP2SEC((u32)-1);
 79 
 80         if (new_timeout < 0 || new_timeout > max_to) {
 81                 pr_err("timeout value must be between 0 and %d\n", max_to);
 82                 return -EINVAL;
 83         }
 84         timeout = new_timeout;
 85         spin_lock(&rc32434_wdt_device.io_lock);
 86         writel(SEC2WTCOMP(timeout), &wdt_reg->wtcompare);
 87         spin_unlock(&rc32434_wdt_device.io_lock);
 88 
 89         return 0;
 90 }
 91 
 92 static void rc32434_wdt_start(void)
 93 {
 94         u32 or, nand;
 95 
 96         spin_lock(&rc32434_wdt_device.io_lock);
 97 
 98         /* zero the counter before enabling */
 99         writel(0, &wdt_reg->wtcount);
100 
101         /* don't generate a non-maskable interrupt,
102          * do a warm reset instead */
103         nand = 1 << RC32434_ERR_WNE;
104         or = 1 << RC32434_ERR_WRE;
105 
106         /* reset the ERRCS timeout bit in case it's set */
107         nand |= 1 << RC32434_ERR_WTO;
108 
109         SET_BITS(wdt_reg->errcs, or, nand);
110 
111         /* set the timeout (either default or based on module param) */
112         rc32434_wdt_set(timeout);
113 
114         /* reset WTC timeout bit and enable WDT */
115         nand = 1 << RC32434_WTC_TO;
116         or = 1 << RC32434_WTC_EN;
117 
118         SET_BITS(wdt_reg->wtc, or, nand);
119 
120         spin_unlock(&rc32434_wdt_device.io_lock);
121         pr_info("Started watchdog timer\n");
122 }
123 
124 static void rc32434_wdt_stop(void)
125 {
126         spin_lock(&rc32434_wdt_device.io_lock);
127 
128         /* Disable WDT */
129         SET_BITS(wdt_reg->wtc, 0, 1 << RC32434_WTC_EN);
130 
131         spin_unlock(&rc32434_wdt_device.io_lock);
132         pr_info("Stopped watchdog timer\n");
133 }
134 
135 static void rc32434_wdt_ping(void)
136 {
137         spin_lock(&rc32434_wdt_device.io_lock);
138         writel(0, &wdt_reg->wtcount);
139         spin_unlock(&rc32434_wdt_device.io_lock);
140 }
141 
142 static int rc32434_wdt_open(struct inode *inode, struct file *file)
143 {
144         if (test_and_set_bit(0, &rc32434_wdt_device.inuse))
145                 return -EBUSY;
146 
147         if (nowayout)
148                 __module_get(THIS_MODULE);
149 
150         rc32434_wdt_start();
151         rc32434_wdt_ping();
152 
153         return nonseekable_open(inode, file);
154 }
155 
156 static int rc32434_wdt_release(struct inode *inode, struct file *file)
157 {
158         if (expect_close == 42) {
159                 rc32434_wdt_stop();
160                 module_put(THIS_MODULE);
161         } else {
162                 pr_crit("device closed unexpectedly. WDT will not stop!\n");
163                 rc32434_wdt_ping();
164         }
165         clear_bit(0, &rc32434_wdt_device.inuse);
166         return 0;
167 }
168 
169 static ssize_t rc32434_wdt_write(struct file *file, const char *data,
170                                 size_t len, loff_t *ppos)
171 {
172         if (len) {
173                 if (!nowayout) {
174                         size_t i;
175 
176                         /* In case it was set long ago */
177                         expect_close = 0;
178 
179                         for (i = 0; i != len; i++) {
180                                 char c;
181                                 if (get_user(c, data + i))
182                                         return -EFAULT;
183                                 if (c == 'V')
184                                         expect_close = 42;
185                         }
186                 }
187                 rc32434_wdt_ping();
188                 return len;
189         }
190         return 0;
191 }
192 
193 static long rc32434_wdt_ioctl(struct file *file, unsigned int cmd,
194                                 unsigned long arg)
195 {
196         void __user *argp = (void __user *)arg;
197         int new_timeout;
198         unsigned int value;
199         static const struct watchdog_info ident = {
200                 .options =              WDIOF_SETTIMEOUT |
201                                         WDIOF_KEEPALIVEPING |
202                                         WDIOF_MAGICCLOSE,
203                 .identity =             "RC32434_WDT Watchdog",
204         };
205         switch (cmd) {
206         case WDIOC_GETSUPPORT:
207                 if (copy_to_user(argp, &ident, sizeof(ident)))
208                         return -EFAULT;
209                 break;
210         case WDIOC_GETSTATUS:
211         case WDIOC_GETBOOTSTATUS:
212                 value = 0;
213                 if (copy_to_user(argp, &value, sizeof(int)))
214                         return -EFAULT;
215                 break;
216         case WDIOC_SETOPTIONS:
217                 if (copy_from_user(&value, argp, sizeof(int)))
218                         return -EFAULT;
219                 switch (value) {
220                 case WDIOS_ENABLECARD:
221                         rc32434_wdt_start();
222                         break;
223                 case WDIOS_DISABLECARD:
224                         rc32434_wdt_stop();
225                         break;
226                 default:
227                         return -EINVAL;
228                 }
229                 break;
230         case WDIOC_KEEPALIVE:
231                 rc32434_wdt_ping();
232                 break;
233         case WDIOC_SETTIMEOUT:
234                 if (copy_from_user(&new_timeout, argp, sizeof(int)))
235                         return -EFAULT;
236                 if (rc32434_wdt_set(new_timeout))
237                         return -EINVAL;
238                 /* Fall through */
239         case WDIOC_GETTIMEOUT:
240                 return copy_to_user(argp, &timeout, sizeof(int));
241         default:
242                 return -ENOTTY;
243         }
244 
245         return 0;
246 }
247 
248 static const struct file_operations rc32434_wdt_fops = {
249         .owner          = THIS_MODULE,
250         .llseek         = no_llseek,
251         .write          = rc32434_wdt_write,
252         .unlocked_ioctl = rc32434_wdt_ioctl,
253         .open           = rc32434_wdt_open,
254         .release        = rc32434_wdt_release,
255 };
256 
257 static struct miscdevice rc32434_wdt_miscdev = {
258         .minor  = WATCHDOG_MINOR,
259         .name   = "watchdog",
260         .fops   = &rc32434_wdt_fops,
261 };
262 
263 static int rc32434_wdt_probe(struct platform_device *pdev)
264 {
265         int ret;
266         struct resource *r;
267 
268         r = platform_get_resource_byname(pdev, IORESOURCE_MEM, "rb532_wdt_res");
269         if (!r) {
270                 pr_err("failed to retrieve resources\n");
271                 return -ENODEV;
272         }
273 
274         wdt_reg = devm_ioremap_nocache(&pdev->dev, r->start, resource_size(r));
275         if (!wdt_reg) {
276                 pr_err("failed to remap I/O resources\n");
277                 return -ENXIO;
278         }
279 
280         spin_lock_init(&rc32434_wdt_device.io_lock);
281 
282         /* Make sure the watchdog is not running */
283         rc32434_wdt_stop();
284 
285         /* Check that the heartbeat value is within it's range;
286          * if not reset to the default */
287         if (rc32434_wdt_set(timeout)) {
288                 rc32434_wdt_set(WATCHDOG_TIMEOUT);
289                 pr_info("timeout value must be between 0 and %d\n",
290                         WTCOMP2SEC((u32)-1));
291         }
292 
293         ret = misc_register(&rc32434_wdt_miscdev);
294         if (ret < 0) {
295                 pr_err("failed to register watchdog device\n");
296                 return ret;
297         }
298 
299         pr_info("Watchdog Timer version " VERSION ", timer margin: %d sec\n",
300                 timeout);
301 
302         return 0;
303 }
304 
305 static int rc32434_wdt_remove(struct platform_device *pdev)
306 {
307         misc_deregister(&rc32434_wdt_miscdev);
308         return 0;
309 }
310 
311 static void rc32434_wdt_shutdown(struct platform_device *pdev)
312 {
313         rc32434_wdt_stop();
314 }
315 
316 static struct platform_driver rc32434_wdt_driver = {
317         .probe          = rc32434_wdt_probe,
318         .remove         = rc32434_wdt_remove,
319         .shutdown       = rc32434_wdt_shutdown,
320         .driver         = {
321                         .name = "rc32434_wdt",
322         }
323 };
324 
325 module_platform_driver(rc32434_wdt_driver);
326 
327 MODULE_AUTHOR("Ondrej Zajicek <santiago@crfreenet.org>,"
328                 "Florian Fainelli <florian@openwrt.org>");
329 MODULE_DESCRIPTION("Driver for the IDT RC32434 SoC watchdog");
330 MODULE_LICENSE("GPL");
331 

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