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.h>
  43
  44 #include <asm/mach-au1x00/au1000.h>
  45
  46 #define MTX1_WDT_INTERVAL       (5 * HZ)
  47
  48 static int ticks = 100 * HZ;
  49
  50 static struct {
  51         struct completion stop;
  52         spinlock_t lock;
  53         int running;
  54         struct timer_list timer;
  55         int queue;
  56         int default_ticks;
  57         unsigned long inuse;
  58         unsigned gpio;
  59         unsigned int gstate;
  60 } mtx1_wdt_device;
  61
  62 static void mtx1_wdt_trigger(struct timer_list *unused)
  63 {
  64         spin_lock(&mtx1_wdt_device.lock);
  65         if (mtx1_wdt_device.running)
  66                 ticks--;
  67
  68         /* toggle wdt gpio */
  69         mtx1_wdt_device.gstate = !mtx1_wdt_device.gstate;
  70         gpio_set_value(mtx1_wdt_device.gpio, mtx1_wdt_device.gstate);
  71
  72         if (mtx1_wdt_device.queue && ticks)
  73                 mod_timer(&mtx1_wdt_device.timer, jiffies + MTX1_WDT_INTERVAL);
  74         else
  75                 complete(&mtx1_wdt_device.stop);
  76         spin_unlock(&mtx1_wdt_device.lock);
  77 }
  78
  79 static void mtx1_wdt_reset(void)
  80 {
  81         ticks = mtx1_wdt_device.default_ticks;
  82 }
  83
  84
  85 static void mtx1_wdt_start(void)
  86 {
  87         unsigned long flags;
  88
  89         spin_lock_irqsave(&mtx1_wdt_device.lock, flags);
  90         if (!mtx1_wdt_device.queue) {
  91                 mtx1_wdt_device.queue = 1;
  92                 mtx1_wdt_device.gstate = 1;
  93                 gpio_set_value(mtx1_wdt_device.gpio, 1);
  94                 mod_timer(&mtx1_wdt_device.timer, jiffies + MTX1_WDT_INTERVAL);
  95         }
  96         mtx1_wdt_device.running++;
  97         spin_unlock_irqrestore(&mtx1_wdt_device.lock, flags);
  98 }
  99
 100 static int mtx1_wdt_stop(void)
 101 {
 102         unsigned long flags;
 103
 104         spin_lock_irqsave(&mtx1_wdt_device.lock, flags);
 105         if (mtx1_wdt_device.queue) {
 106                 mtx1_wdt_device.queue = 0;
 107                 mtx1_wdt_device.gstate = 0;
 108                 gpio_set_value(mtx1_wdt_device.gpio, 0);
 109         }
 110         ticks = mtx1_wdt_device.default_ticks;
 111         spin_unlock_irqrestore(&mtx1_wdt_device.lock, flags);
 112         return 0;
 113 }
 114
 115 /* Filesystem functions */
 116
 117 static int mtx1_wdt_open(struct inode *inode, struct file *file)
 118 {
 119         if (test_and_set_bit(0, &mtx1_wdt_device.inuse))
 120                 return -EBUSY;
 121         return nonseekable_open(inode, file);
 122 }
 123
 124
 125 static int mtx1_wdt_release(struct inode *inode, struct file *file)
 126 {
 127         clear_bit(0, &mtx1_wdt_device.inuse);
 128         return 0;
 129 }
 130
 131 static long mtx1_wdt_ioctl(struct file *file, unsigned int cmd,
 132                                                         unsigned long arg)
 133 {
 134         void __user *argp = (void __user *)arg;
 135         int __user *p = (int __user *)argp;
 136         unsigned int value;
 137         static const struct watchdog_info ident = {
 138                 .options = WDIOF_CARDRESET,
 139                 .identity = "MTX-1 WDT",
 140         };
 141
 142         switch (cmd) {
 143         case WDIOC_GETSUPPORT:
 144                 if (copy_to_user(argp, &ident, sizeof(ident)))
 145                         return -EFAULT;
 146                 break;
 147         case WDIOC_GETSTATUS:
 148         case WDIOC_GETBOOTSTATUS:
 149                 put_user(0, p);
 150                 break;
 151         case WDIOC_SETOPTIONS:
 152                 if (get_user(value, p))
 153                         return -EFAULT;
 154                 if (value & WDIOS_ENABLECARD)
 155                         mtx1_wdt_start();
 156                 else if (value & WDIOS_DISABLECARD)
 157                         mtx1_wdt_stop();
 158                 else
 159                         return -EINVAL;
 160                 return 0;
 161         case WDIOC_KEEPALIVE:
 162                 mtx1_wdt_reset();
 163                 break;
 164         default:
 165                 return -ENOTTY;
 166         }
 167         return 0;
 168 }
 169
 170
 171 static ssize_t mtx1_wdt_write(struct file *file, const char *buf,
 172                                                 size_t count, loff_t *ppos)
 173 {
 174         if (!count)
 175                 return -EIO;
 176         mtx1_wdt_reset();
 177         return count;
 178 }
 179
 180 static const struct file_operations mtx1_wdt_fops = {
 181         .owner          = THIS_MODULE,
 182         .llseek         = no_llseek,
 183         .unlocked_ioctl = mtx1_wdt_ioctl,
 184         .open           = mtx1_wdt_open,
 185         .write          = mtx1_wdt_write,
 186         .release        = mtx1_wdt_release,
 187 };
 188
 189
 190 static struct miscdevice mtx1_wdt_misc = {
 191         .minor  = WATCHDOG_MINOR,
 192         .name   = "watchdog",
 193         .fops   = &mtx1_wdt_fops,
 194 };
 195
 196
 197 static int mtx1_wdt_probe(struct platform_device *pdev)
 198 {
 199         int ret;
 200
 201         mtx1_wdt_device.gpio = pdev->resource[0].start;
 202         ret = devm_gpio_request_one(&pdev->dev, mtx1_wdt_device.gpio,
 203                                 GPIOF_OUT_INIT_HIGH, "mtx1-wdt");
 204         if (ret < 0) {
 205                 dev_err(&pdev->dev, "failed to request gpio");
 206                 return ret;
 207         }
 208
 209         spin_lock_init(&mtx1_wdt_device.lock);
 210         init_completion(&mtx1_wdt_device.stop);
 211         mtx1_wdt_device.queue = 0;
 212         clear_bit(0, &mtx1_wdt_device.inuse);
 213         timer_setup(&mtx1_wdt_device.timer, mtx1_wdt_trigger, 0);
 214         mtx1_wdt_device.default_ticks = ticks;
 215
 216         ret = misc_register(&mtx1_wdt_misc);
 217         if (ret < 0) {
 218                 dev_err(&pdev->dev, "failed to register\n");
 219                 return ret;
 220         }
 221         mtx1_wdt_start();
 222         dev_info(&pdev->dev, "MTX-1 Watchdog driver\n");
 223         return 0;
 224 }
 225
 226 static int mtx1_wdt_remove(struct platform_device *pdev)
 227 {
 228         /* FIXME: do we need to lock this test ? */
 229         if (mtx1_wdt_device.queue) {
 230                 mtx1_wdt_device.queue = 0;
 231                 wait_for_completion(&mtx1_wdt_device.stop);
 232         }
 233
 234         misc_deregister(&mtx1_wdt_misc);
 235         return 0;
 236 }
 237
 238 static struct platform_driver mtx1_wdt_driver = {
 239         .probe = mtx1_wdt_probe,
 240         .remove = mtx1_wdt_remove,
 241         .driver.name = "mtx1-wdt",
 242         .driver.owner = THIS_MODULE,
 243 };
 244
 245 module_platform_driver(mtx1_wdt_driver);
 246
 247 MODULE_AUTHOR("Michael Stickel, Florian Fainelli");
 248 MODULE_DESCRIPTION("Driver for the MTX-1 watchdog");
 249 MODULE_LICENSE("GPL");
 250 MODULE_ALIAS("platform:mtx1-wdt");