drivers/watchdog/ixp4xx_wdt.c

   1 /*
   2  * drivers/char/watchdog/ixp4xx_wdt.c
   3  *
   4  * Watchdog driver for Intel IXP4xx network processors
   5  *
   6  * Author: Deepak Saxena <dsaxena@plexity.net>
   7  *
   8  * Copyright 2004 (c) MontaVista, Software, Inc.
   9  * Based on sa1100 driver, Copyright (C) 2000 Oleg Drokin <green@crimea.edu>
  10  *
  11  * This file is licensed under  the terms of the GNU General Public
  12  * License version 2. This program is licensed "as is" without any
  13  * warranty of any kind, whether express or implied.
  14  */
  15
  16 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  17
  18 #include <linux/module.h>
  19 #include <linux/moduleparam.h>
  20 #include <linux/types.h>
  21 #include <linux/kernel.h>
  22 #include <linux/fs.h>
  23 #include <linux/miscdevice.h>
  24 #include <linux/watchdog.h>
  25 #include <linux/init.h>
  26 #include <linux/bitops.h>
  27 #include <linux/uaccess.h>
  28 #include <mach/hardware.h>
  29
  30 static bool nowayout = WATCHDOG_NOWAYOUT;
  31 static int heartbeat = 60;      /* (secs) Default is 1 minute */
  32 static unsigned long wdt_status;
  33 static unsigned long boot_status;
  34 static DEFINE_SPINLOCK(wdt_lock);
  35
  36 #define WDT_TICK_RATE (IXP4XX_PERIPHERAL_BUS_CLOCK * 1000000UL)
  37
  38 #define WDT_IN_USE              0
  39 #define WDT_OK_TO_CLOSE         1
  40
  41 static void wdt_enable(void)
  42 {
  43         spin_lock(&wdt_lock);
  44         *IXP4XX_OSWK = IXP4XX_WDT_KEY;
  45         *IXP4XX_OSWE = 0;
  46         *IXP4XX_OSWT = WDT_TICK_RATE * heartbeat;
  47         *IXP4XX_OSWE = IXP4XX_WDT_COUNT_ENABLE | IXP4XX_WDT_RESET_ENABLE;
  48         *IXP4XX_OSWK = 0;
  49         spin_unlock(&wdt_lock);
  50 }
  51
  52 static void wdt_disable(void)
  53 {
  54         spin_lock(&wdt_lock);
  55         *IXP4XX_OSWK = IXP4XX_WDT_KEY;
  56         *IXP4XX_OSWE = 0;
  57         *IXP4XX_OSWK = 0;
  58         spin_unlock(&wdt_lock);
  59 }
  60
  61 static int ixp4xx_wdt_open(struct inode *inode, struct file *file)
  62 {
  63         if (test_and_set_bit(WDT_IN_USE, &wdt_status))
  64                 return -EBUSY;
  65
  66         clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
  67         wdt_enable();
  68         return nonseekable_open(inode, file);
  69 }
  70
  71 static ssize_t
  72 ixp4xx_wdt_write(struct file *file, const char *data, size_t len, loff_t *ppos)
  73 {
  74         if (len) {
  75                 if (!nowayout) {
  76                         size_t i;
  77
  78                         clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
  79
  80                         for (i = 0; i != len; i++) {
  81                                 char c;
  82
  83                                 if (get_user(c, data + i))
  84                                         return -EFAULT;
  85                                 if (c == 'V')
  86                                         set_bit(WDT_OK_TO_CLOSE, &wdt_status);
  87                         }
  88                 }
  89                 wdt_enable();
  90         }
  91         return len;
  92 }
  93
  94 static const struct watchdog_info ident = {
  95         .options        = WDIOF_CARDRESET | WDIOF_MAGICCLOSE |
  96                           WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
  97         .identity       = "IXP4xx Watchdog",
  98 };
  99
 100
 101 static long ixp4xx_wdt_ioctl(struct file *file, unsigned int cmd,
 102                                                         unsigned long arg)
 103 {
 104         int ret = -ENOTTY;
 105         int time;
 106
 107         switch (cmd) {
 108         case WDIOC_GETSUPPORT:
 109                 ret = copy_to_user((struct watchdog_info *)arg, &ident,
 110                                    sizeof(ident)) ? -EFAULT : 0;
 111                 break;
 112
 113         case WDIOC_GETSTATUS:
 114                 ret = put_user(0, (int *)arg);
 115                 break;
 116
 117         case WDIOC_GETBOOTSTATUS:
 118                 ret = put_user(boot_status, (int *)arg);
 119                 break;
 120
 121         case WDIOC_KEEPALIVE:
 122                 wdt_enable();
 123                 ret = 0;
 124                 break;
 125
 126         case WDIOC_SETTIMEOUT:
 127                 ret = get_user(time, (int *)arg);
 128                 if (ret)
 129                         break;
 130
 131                 if (time <= 0 || time > 60) {
 132                         ret = -EINVAL;
 133                         break;
 134                 }
 135
 136                 heartbeat = time;
 137                 wdt_enable();
 138                 /* Fall through */
 139
 140         case WDIOC_GETTIMEOUT:
 141                 ret = put_user(heartbeat, (int *)arg);
 142                 break;
 143         }
 144         return ret;
 145 }
 146
 147 static int ixp4xx_wdt_release(struct inode *inode, struct file *file)
 148 {
 149         if (test_bit(WDT_OK_TO_CLOSE, &wdt_status))
 150                 wdt_disable();
 151         else
 152                 pr_crit("Device closed unexpectedly - timer will not stop\n");
 153         clear_bit(WDT_IN_USE, &wdt_status);
 154         clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
 155
 156         return 0;
 157 }
 158
 159
 160 static const struct file_operations ixp4xx_wdt_fops = {
 161         .owner          = THIS_MODULE,
 162         .llseek         = no_llseek,
 163         .write          = ixp4xx_wdt_write,
 164         .unlocked_ioctl = ixp4xx_wdt_ioctl,
 165         .open           = ixp4xx_wdt_open,
 166         .release        = ixp4xx_wdt_release,
 167 };
 168
 169 static struct miscdevice ixp4xx_wdt_miscdev = {
 170         .minor          = WATCHDOG_MINOR,
 171         .name           = "watchdog",
 172         .fops           = &ixp4xx_wdt_fops,
 173 };
 174
 175 static int __init ixp4xx_wdt_init(void)
 176 {
 177         int ret;
 178
 179         if (!(read_cpuid_id() & 0xf) && !cpu_is_ixp46x()) {
 180                 pr_err("Rev. A0 IXP42x CPU detected - watchdog disabled\n");
 181
 182                 return -ENODEV;
 183         }
 184         boot_status = (*IXP4XX_OSST & IXP4XX_OSST_TIMER_WARM_RESET) ?
 185                         WDIOF_CARDRESET : 0;
 186         ret = misc_register(&ixp4xx_wdt_miscdev);
 187         if (ret == 0)
 188                 pr_info("timer heartbeat %d sec\n", heartbeat);
 189         return ret;
 190 }
 191
 192 static void __exit ixp4xx_wdt_exit(void)
 193 {
 194         misc_deregister(&ixp4xx_wdt_miscdev);
 195 }
 196
 197
 198 module_init(ixp4xx_wdt_init);
 199 module_exit(ixp4xx_wdt_exit);
 200
 201 MODULE_AUTHOR("Deepak Saxena <dsaxena@plexity.net>");
 202 MODULE_DESCRIPTION("IXP4xx Network Processor Watchdog");
 203
 204 module_param(heartbeat, int, 0);
 205 MODULE_PARM_DESC(heartbeat, "Watchdog heartbeat in seconds (default 60s)");
 206
 207 module_param(nowayout, bool, 0);
 208 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started");
 209
 210 MODULE_LICENSE("GPL");