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Linux/drivers/watchdog/mtx-1_wdt.c

  1 /*
  2  *      Driver for the MTX-1 Watchdog.
  3  *
  4  *      (C) Copyright 2005 4G Systems <info@4g-systems.biz>,
  5  *                                                      All Rights Reserved.
  6  *                              http://www.4g-systems.biz
  7  *
  8  *      (C) Copyright 2007 OpenWrt.org, Florian Fainelli <florian@openwrt.org>
  9  *
 10  *      This program is free software; you can redistribute it and/or
 11  *      modify it under the terms of the GNU General Public License
 12  *      as published by the Free Software Foundation; either version
 13  *      2 of the License, or (at your option) any later version.
 14  *
 15  *      Neither Michael Stickel nor 4G Systems admit liability nor provide
 16  *      warranty for any of this software. This material is provided
 17  *      "AS-IS" and at no charge.
 18  *
 19  *      (c) Copyright 2005    4G Systems <info@4g-systems.biz>
 20  *
 21  *      Release 0.01.
 22  *      Author: Michael Stickel  michael.stickel@4g-systems.biz
 23  *
 24  *      Release 0.02.
 25  *      Author: Florian Fainelli florian@openwrt.org
 26  *              use the Linux watchdog/timer APIs
 27  *
 28  *      The Watchdog is configured to reset the MTX-1
 29  *      if it is not triggered for 100 seconds.
 30  *      It should not be triggered more often than 1.6 seconds.
 31  *
 32  *      A timer triggers the watchdog every 5 seconds, until
 33  *      it is opened for the first time. After the first open
 34  *      it MUST be triggered every 2..95 seconds.
 35  */
 36 
 37 #include <linux/module.h>
 38 #include <linux/moduleparam.h>
 39 #include <linux/types.h>
 40 #include <linux/errno.h>
 41 #include <linux/miscdevice.h>
 42 #include <linux/fs.h>
 43 #include <linux/ioport.h>
 44 #include <linux/timer.h>
 45 #include <linux/completion.h>
 46 #include <linux/jiffies.h>
 47 #include <linux/watchdog.h>
 48 #include <linux/platform_device.h>
 49 #include <linux/io.h>
 50 #include <linux/uaccess.h>
 51 #include <linux/gpio.h>
 52 
 53 #include <asm/mach-au1x00/au1000.h>
 54 
 55 #define MTX1_WDT_INTERVAL       (5 * HZ)
 56 
 57 static int ticks = 100 * HZ;
 58 
 59 static struct {
 60         struct completion stop;
 61         spinlock_t lock;
 62         int running;
 63         struct timer_list timer;
 64         int queue;
 65         int default_ticks;
 66         unsigned long inuse;
 67         unsigned gpio;
 68         unsigned int gstate;
 69 } mtx1_wdt_device;
 70 
 71 static void mtx1_wdt_trigger(unsigned long unused)
 72 {
 73         spin_lock(&mtx1_wdt_device.lock);
 74         if (mtx1_wdt_device.running)
 75                 ticks--;
 76 
 77         /* toggle wdt gpio */
 78         mtx1_wdt_device.gstate = !mtx1_wdt_device.gstate;
 79         gpio_set_value(mtx1_wdt_device.gpio, mtx1_wdt_device.gstate);
 80 
 81         if (mtx1_wdt_device.queue && ticks)
 82                 mod_timer(&mtx1_wdt_device.timer, jiffies + MTX1_WDT_INTERVAL);
 83         else
 84                 complete(&mtx1_wdt_device.stop);
 85         spin_unlock(&mtx1_wdt_device.lock);
 86 }
 87 
 88 static void mtx1_wdt_reset(void)
 89 {
 90         ticks = mtx1_wdt_device.default_ticks;
 91 }
 92 
 93 
 94 static void mtx1_wdt_start(void)
 95 {
 96         unsigned long flags;
 97 
 98         spin_lock_irqsave(&mtx1_wdt_device.lock, flags);
 99         if (!mtx1_wdt_device.queue) {
100                 mtx1_wdt_device.queue = 1;
101                 mtx1_wdt_device.gstate = 1;
102                 gpio_set_value(mtx1_wdt_device.gpio, 1);
103                 mod_timer(&mtx1_wdt_device.timer, jiffies + MTX1_WDT_INTERVAL);
104         }
105         mtx1_wdt_device.running++;
106         spin_unlock_irqrestore(&mtx1_wdt_device.lock, flags);
107 }
108 
109 static int mtx1_wdt_stop(void)
110 {
111         unsigned long flags;
112 
113         spin_lock_irqsave(&mtx1_wdt_device.lock, flags);
114         if (mtx1_wdt_device.queue) {
115                 mtx1_wdt_device.queue = 0;
116                 mtx1_wdt_device.gstate = 0;
117                 gpio_set_value(mtx1_wdt_device.gpio, 0);
118         }
119         ticks = mtx1_wdt_device.default_ticks;
120         spin_unlock_irqrestore(&mtx1_wdt_device.lock, flags);
121         return 0;
122 }
123 
124 /* Filesystem functions */
125 
126 static int mtx1_wdt_open(struct inode *inode, struct file *file)
127 {
128         if (test_and_set_bit(0, &mtx1_wdt_device.inuse))
129                 return -EBUSY;
130         return nonseekable_open(inode, file);
131 }
132 
133 
134 static int mtx1_wdt_release(struct inode *inode, struct file *file)
135 {
136         clear_bit(0, &mtx1_wdt_device.inuse);
137         return 0;
138 }
139 
140 static long mtx1_wdt_ioctl(struct file *file, unsigned int cmd,
141                                                         unsigned long arg)
142 {
143         void __user *argp = (void __user *)arg;
144         int __user *p = (int __user *)argp;
145         unsigned int value;
146         static const struct watchdog_info ident = {
147                 .options = WDIOF_CARDRESET,
148                 .identity = "MTX-1 WDT",
149         };
150 
151         switch (cmd) {
152         case WDIOC_GETSUPPORT:
153                 if (copy_to_user(argp, &ident, sizeof(ident)))
154                         return -EFAULT;
155                 break;
156         case WDIOC_GETSTATUS:
157         case WDIOC_GETBOOTSTATUS:
158                 put_user(0, p);
159                 break;
160         case WDIOC_SETOPTIONS:
161                 if (get_user(value, p))
162                         return -EFAULT;
163                 if (value & WDIOS_ENABLECARD)
164                         mtx1_wdt_start();
165                 else if (value & WDIOS_DISABLECARD)
166                         mtx1_wdt_stop();
167                 else
168                         return -EINVAL;
169                 return 0;
170         case WDIOC_KEEPALIVE:
171                 mtx1_wdt_reset();
172                 break;
173         default:
174                 return -ENOTTY;
175         }
176         return 0;
177 }
178 
179 
180 static ssize_t mtx1_wdt_write(struct file *file, const char *buf,
181                                                 size_t count, loff_t *ppos)
182 {
183         if (!count)
184                 return -EIO;
185         mtx1_wdt_reset();
186         return count;
187 }
188 
189 static const struct file_operations mtx1_wdt_fops = {
190         .owner          = THIS_MODULE,
191         .llseek         = no_llseek,
192         .unlocked_ioctl = mtx1_wdt_ioctl,
193         .open           = mtx1_wdt_open,
194         .write          = mtx1_wdt_write,
195         .release        = mtx1_wdt_release,
196 };
197 
198 
199 static struct miscdevice mtx1_wdt_misc = {
200         .minor  = WATCHDOG_MINOR,
201         .name   = "watchdog",
202         .fops   = &mtx1_wdt_fops,
203 };
204 
205 
206 static int mtx1_wdt_probe(struct platform_device *pdev)
207 {
208         int ret;
209 
210         mtx1_wdt_device.gpio = pdev->resource[0].start;
211         ret = devm_gpio_request_one(&pdev->dev, mtx1_wdt_device.gpio,
212                                 GPIOF_OUT_INIT_HIGH, "mtx1-wdt");
213         if (ret < 0) {
214                 dev_err(&pdev->dev, "failed to request gpio");
215                 return ret;
216         }
217 
218         spin_lock_init(&mtx1_wdt_device.lock);
219         init_completion(&mtx1_wdt_device.stop);
220         mtx1_wdt_device.queue = 0;
221         clear_bit(0, &mtx1_wdt_device.inuse);
222         setup_timer(&mtx1_wdt_device.timer, mtx1_wdt_trigger, 0L);
223         mtx1_wdt_device.default_ticks = ticks;
224 
225         ret = misc_register(&mtx1_wdt_misc);
226         if (ret < 0) {
227                 dev_err(&pdev->dev, "failed to register\n");
228                 return ret;
229         }
230         mtx1_wdt_start();
231         dev_info(&pdev->dev, "MTX-1 Watchdog driver\n");
232         return 0;
233 }
234 
235 static int mtx1_wdt_remove(struct platform_device *pdev)
236 {
237         /* FIXME: do we need to lock this test ? */
238         if (mtx1_wdt_device.queue) {
239                 mtx1_wdt_device.queue = 0;
240                 wait_for_completion(&mtx1_wdt_device.stop);
241         }
242 
243         misc_deregister(&mtx1_wdt_misc);
244         return 0;
245 }
246 
247 static struct platform_driver mtx1_wdt_driver = {
248         .probe = mtx1_wdt_probe,
249         .remove = mtx1_wdt_remove,
250         .driver.name = "mtx1-wdt",
251         .driver.owner = THIS_MODULE,
252 };
253 
254 module_platform_driver(mtx1_wdt_driver);
255 
256 MODULE_AUTHOR("Michael Stickel, Florian Fainelli");
257 MODULE_DESCRIPTION("Driver for the MTX-1 watchdog");
258 MODULE_LICENSE("GPL");
259 MODULE_ALIAS("platform:mtx1-wdt");
260 

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