drivers/watchdog/mtx-1_wdt.c

   1 // SPDX-License-Identifier: GPL-2.0+
   2 /*
   3  *      Driver for the MTX-1 Watchdog.
   4  *
   5  *      (C) Copyright 2005 4G Systems <info@4g-systems.biz>,
   6  *                                                      All Rights Reserved.
   7  *                              http://www.4g-systems.biz
   8  *
   9  *      (C) Copyright 2007 OpenWrt.org, Florian Fainelli <florian@openwrt.org>
  10  *      (c) Copyright 2005    4G Systems <info@4g-systems.biz>
  11  *
  12  *      Release 0.01.
  13  *      Author: Michael Stickel  michael.stickel@4g-systems.biz
  14  *
  15  *      Release 0.02.
  16  *      Author: Florian Fainelli florian@openwrt.org
  17  *              use the Linux watchdog/timer APIs
  18  *
  19  *      The Watchdog is configured to reset the MTX-1
  20  *      if it is not triggered for 100 seconds.
  21  *      It should not be triggered more often than 1.6 seconds.
  22  *
  23  *      A timer triggers the watchdog every 5 seconds, until
  24  *      it is opened for the first time. After the first open
  25  *      it MUST be triggered every 2..95 seconds.
  26  */
  27
  28 #include <linux/module.h>
  29 #include <linux/moduleparam.h>
  30 #include <linux/types.h>
  31 #include <linux/errno.h>
  32 #include <linux/miscdevice.h>
  33 #include <linux/fs.h>
  34 #include <linux/ioport.h>
  35 #include <linux/timer.h>
  36 #include <linux/completion.h>
  37 #include <linux/jiffies.h>
  38 #include <linux/watchdog.h>
  39 #include <linux/platform_device.h>
  40 #include <linux/io.h>
  41 #include <linux/uaccess.h>
  42 #include <linux/gpio/consumer.h>
  43
  44 #define MTX1_WDT_INTERVAL       (5 * HZ)
  45
  46 static int ticks = 100 * HZ;
  47
  48 static struct {
  49         struct completion stop;
  50         spinlock_t lock;
  51         int running;
  52         struct timer_list timer;
  53         int queue;
  54         int default_ticks;
  55         unsigned long inuse;
  56         struct gpio_desc *gpiod;
  57         unsigned int gstate;
  58 } mtx1_wdt_device;
  59
  60 static void mtx1_wdt_trigger(struct timer_list *unused)
  61 {
  62         spin_lock(&mtx1_wdt_device.lock);
  63         if (mtx1_wdt_device.running)
  64                 ticks--;
  65
  66         /* toggle wdt gpio */
  67         mtx1_wdt_device.gstate = !mtx1_wdt_device.gstate;
  68         gpiod_set_value(mtx1_wdt_device.gpiod, mtx1_wdt_device.gstate);
  69
  70         if (mtx1_wdt_device.queue && ticks)
  71                 mod_timer(&mtx1_wdt_device.timer, jiffies + MTX1_WDT_INTERVAL);
  72         else
  73                 complete(&mtx1_wdt_device.stop);
  74         spin_unlock(&mtx1_wdt_device.lock);
  75 }
  76
  77 static void mtx1_wdt_reset(void)
  78 {
  79         ticks = mtx1_wdt_device.default_ticks;
  80 }
  81
  82
  83 static void mtx1_wdt_start(void)
  84 {
  85         unsigned long flags;
  86
  87         spin_lock_irqsave(&mtx1_wdt_device.lock, flags);
  88         if (!mtx1_wdt_device.queue) {
  89                 mtx1_wdt_device.queue = 1;
  90                 mtx1_wdt_device.gstate = 1;
  91                 gpiod_set_value(mtx1_wdt_device.gpiod, 1);
  92                 mod_timer(&mtx1_wdt_device.timer, jiffies + MTX1_WDT_INTERVAL);
  93         }
  94         mtx1_wdt_device.running++;
  95         spin_unlock_irqrestore(&mtx1_wdt_device.lock, flags);
  96 }
  97
  98 static int mtx1_wdt_stop(void)
  99 {
 100         unsigned long flags;
 101
 102         spin_lock_irqsave(&mtx1_wdt_device.lock, flags);
 103         if (mtx1_wdt_device.queue) {
 104                 mtx1_wdt_device.queue = 0;
 105                 mtx1_wdt_device.gstate = 0;
 106                 gpiod_set_value(mtx1_wdt_device.gpiod, 0);
 107         }
 108         ticks = mtx1_wdt_device.default_ticks;
 109         spin_unlock_irqrestore(&mtx1_wdt_device.lock, flags);
 110         return 0;
 111 }
 112
 113 /* Filesystem functions */
 114
 115 static int mtx1_wdt_open(struct inode *inode, struct file *file)
 116 {
 117         if (test_and_set_bit(0, &mtx1_wdt_device.inuse))
 118                 return -EBUSY;
 119         return stream_open(inode, file);
 120 }
 121
 122
 123 static int mtx1_wdt_release(struct inode *inode, struct file *file)
 124 {
 125         clear_bit(0, &mtx1_wdt_device.inuse);
 126         return 0;
 127 }
 128
 129 static long mtx1_wdt_ioctl(struct file *file, unsigned int cmd,
 130                                                         unsigned long arg)
 131 {
 132         void __user *argp = (void __user *)arg;
 133         int __user *p = (int __user *)argp;
 134         unsigned int value;
 135         static const struct watchdog_info ident = {
 136                 .options = WDIOF_CARDRESET,
 137                 .identity = "MTX-1 WDT",
 138         };
 139
 140         switch (cmd) {
 141         case WDIOC_GETSUPPORT:
 142                 if (copy_to_user(argp, &ident, sizeof(ident)))
 143                         return -EFAULT;
 144                 break;
 145         case WDIOC_GETSTATUS:
 146         case WDIOC_GETBOOTSTATUS:
 147                 put_user(0, p);
 148                 break;
 149         case WDIOC_SETOPTIONS:
 150                 if (get_user(value, p))
 151                         return -EFAULT;
 152                 if (value & WDIOS_ENABLECARD)
 153                         mtx1_wdt_start();
 154                 else if (value & WDIOS_DISABLECARD)
 155                         mtx1_wdt_stop();
 156                 else
 157                         return -EINVAL;
 158                 return 0;
 159         case WDIOC_KEEPALIVE:
 160                 mtx1_wdt_reset();
 161                 break;
 162         default:
 163                 return -ENOTTY;
 164         }
 165         return 0;
 166 }
 167
 168
 169 static ssize_t mtx1_wdt_write(struct file *file, const char *buf,
 170                                                 size_t count, loff_t *ppos)
 171 {
 172         if (!count)
 173                 return -EIO;
 174         mtx1_wdt_reset();
 175         return count;
 176 }
 177
 178 static const struct file_operations mtx1_wdt_fops = {
 179         .owner          = THIS_MODULE,
 180         .unlocked_ioctl = mtx1_wdt_ioctl,
 181         .compat_ioctl   = compat_ptr_ioctl,
 182         .open           = mtx1_wdt_open,
 183         .write          = mtx1_wdt_write,
 184         .release        = mtx1_wdt_release,
 185 };
 186
 187
 188 static struct miscdevice mtx1_wdt_misc = {
 189         .minor  = WATCHDOG_MINOR,
 190         .name   = "watchdog",
 191         .fops   = &mtx1_wdt_fops,
 192 };
 193
 194
 195 static int mtx1_wdt_probe(struct platform_device *pdev)
 196 {
 197         int ret;
 198
 199         mtx1_wdt_device.gpiod = devm_gpiod_get(&pdev->dev,
 200                                                NULL, GPIOD_OUT_HIGH);
 201         if (IS_ERR(mtx1_wdt_device.gpiod)) {
 202                 dev_err(&pdev->dev, "failed to request gpio");
 203                 return PTR_ERR(mtx1_wdt_device.gpiod);
 204         }
 205
 206         spin_lock_init(&mtx1_wdt_device.lock);
 207         init_completion(&mtx1_wdt_device.stop);
 208         mtx1_wdt_device.queue = 0;
 209         clear_bit(0, &mtx1_wdt_device.inuse);
 210         timer_setup(&mtx1_wdt_device.timer, mtx1_wdt_trigger, 0);
 211         mtx1_wdt_device.default_ticks = ticks;
 212
 213         ret = misc_register(&mtx1_wdt_misc);
 214         if (ret < 0) {
 215                 dev_err(&pdev->dev, "failed to register\n");
 216                 return ret;
 217         }
 218         mtx1_wdt_start();
 219         dev_info(&pdev->dev, "MTX-1 Watchdog driver\n");
 220         return 0;
 221 }
 222
 223 static void mtx1_wdt_remove(struct platform_device *pdev)
 224 {
 225         /* FIXME: do we need to lock this test ? */
 226         if (mtx1_wdt_device.queue) {
 227                 mtx1_wdt_device.queue = 0;
 228                 wait_for_completion(&mtx1_wdt_device.stop);
 229         }
 230
 231         misc_deregister(&mtx1_wdt_misc);
 232 }
 233
 234 static struct platform_driver mtx1_wdt_driver = {
 235         .probe = mtx1_wdt_probe,
 236         .remove = mtx1_wdt_remove,
 237         .driver.name = "mtx1-wdt",
 238 };
 239
 240 module_platform_driver(mtx1_wdt_driver);
 241
 242 MODULE_AUTHOR("Michael Stickel, Florian Fainelli");
 243 MODULE_DESCRIPTION("Driver for the MTX-1 watchdog");
 244 MODULE_LICENSE("GPL");
 245 MODULE_ALIAS("platform:mtx1-wdt");