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   1 /*
   2  * drivers/watchdog/orion5x_wdt.c
   3  *
   4  * Watchdog driver for Orion5x processors
   5  *
   6  * Author: Sylver Bruneau <sylver.bruneau@googlemail.com>
   7  *
   8  * This file is licensed under  the terms of the GNU General Public
   9  * License version 2. This program is licensed "as is" without any
  10  * warranty of any kind, whether express or implied.
  11  */
  12
  13 #include <linux/module.h>
  14 #include <linux/moduleparam.h>
  15 #include <linux/types.h>
  16 #include <linux/kernel.h>
  17 #include <linux/fs.h>
  18 #include <linux/miscdevice.h>
  19 #include <linux/watchdog.h>
  20 #include <linux/init.h>
  21 #include <linux/uaccess.h>
  22 #include <linux/io.h>
  23
  24 /*
  25  * Watchdog timer block registers.
  26  */
  27 #define TIMER_CTRL              (TIMER_VIRT_BASE + 0x0000)
  28 #define  WDT_EN                 0x0010
  29 #define WDT_VAL                 (TIMER_VIRT_BASE + 0x0024)
  30
  31 #define WDT_MAX_DURATION        (0xffffffff / ORION5X_TCLK)
  32 #define WDT_IN_USE              0
  33 #define WDT_OK_TO_CLOSE         1
  34
  35 static int nowayout = WATCHDOG_NOWAYOUT;
  36 static int heartbeat =  WDT_MAX_DURATION;       /* (seconds) */
  37 static unsigned long wdt_status;
  38
  39 static void wdt_enable(void)
  40 {
  41         u32 reg;
  42
  43         /* Set watchdog duration */
  44         writel(ORION5X_TCLK * heartbeat, WDT_VAL);
  45
  46         /* Clear watchdog timer interrupt */
  47         reg = readl(BRIDGE_CAUSE);
  48         reg &= ~WDT_INT_REQ;
  49         writel(reg, BRIDGE_CAUSE);
  50
  51         /* Enable watchdog timer */
  52         reg = readl(TIMER_CTRL);
  53         reg |= WDT_EN;
  54         writel(reg, TIMER_CTRL);
  55
  56         /* Enable reset on watchdog */
  57         reg = readl(CPU_RESET_MASK);
  58         reg |= WDT_RESET;
  59         writel(reg, CPU_RESET_MASK);
  60 }
  61
  62 static void wdt_disable(void)
  63 {
  64         u32 reg;
  65
  66         /* Disable reset on watchdog */
  67         reg = readl(CPU_RESET_MASK);
  68         reg &= ~WDT_RESET;
  69         writel(reg, CPU_RESET_MASK);
  70
  71         /* Disable watchdog timer */
  72         reg = readl(TIMER_CTRL);
  73         reg &= ~WDT_EN;
  74         writel(reg, TIMER_CTRL);
  75 }
  76
  77 static int orion5x_wdt_open(struct inode *inode, struct file *file)
  78 {
  79         if (test_and_set_bit(WDT_IN_USE, &wdt_status))
  80                 return -EBUSY;
  81         clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
  82         wdt_enable();
  83         return nonseekable_open(inode, file);
  84 }
  85
  86 static int orion5x_wdt_get_timeleft(int *time_left)
  87 {
  88         *time_left = readl(WDT_VAL) / ORION5X_TCLK;
  89         return 0;
  90 }
  91
  92 static ssize_t orion5x_wdt_write(struct file *file, const char *data,
  93                                         size_t len, loff_t *ppos)
  94 {
  95         if (len) {
  96                 if (!nowayout) {
  97                         size_t i;
  98
  99                         clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
 100                         for (i = 0; i != len; i++) {
 101                                 char c;
 102
 103                                 if (get_user(c, data + i))
 104                                         return -EFAULT;
 105                                 if (c == 'V')
 106                                         set_bit(WDT_OK_TO_CLOSE, &wdt_status);
 107                         }
 108                 }
 109                 wdt_enable();
 110         }
 111         return len;
 112 }
 113
 114 static struct watchdog_info ident = {
 115         .options        = WDIOF_MAGICCLOSE | WDIOF_SETTIMEOUT |
 116                           WDIOF_KEEPALIVEPING,
 117         .identity       = "Orion5x Watchdog",
 118 };
 119
 120
 121 static long orion5x_wdt_ioctl(struct file *file, unsigned int cmd,
 122                                 unsigned long arg)
 123 {
 124         int ret = -ENOTTY;
 125         int time;
 126
 127         switch (cmd) {
 128         case WDIOC_GETSUPPORT:
 129                 ret = copy_to_user((struct watchdog_info *)arg, &ident,
 130                                    sizeof(ident)) ? -EFAULT : 0;
 131                 break;
 132
 133         case WDIOC_GETSTATUS:
 134         case WDIOC_GETBOOTSTATUS:
 135                 ret = put_user(0, (int *)arg);
 136                 break;
 137
 138         case WDIOC_KEEPALIVE:
 139                 wdt_enable();
 140                 ret = 0;
 141                 break;
 142
 143         case WDIOC_SETTIMEOUT:
 144                 ret = get_user(time, (int *)arg);
 145                 if (ret)
 146                         break;
 147
 148                 if (time <= 0 || time > WDT_MAX_DURATION) {
 149                         ret = -EINVAL;
 150                         break;
 151                 }
 152                 heartbeat = time;
 153                 wdt_enable();
 154                 /* Fall through */
 155
 156         case WDIOC_GETTIMEOUT:
 157                 ret = put_user(heartbeat, (int *)arg);
 158                 break;
 159
 160         case WDIOC_GETTIMELEFT:
 161                 if (orion5x_wdt_get_timeleft(&time)) {
 162                         ret = -EINVAL;
 163                         break;
 164                 }
 165                 ret = put_user(time, (int *)arg);
 166                 break;
 167         }
 168         return ret;
 169 }
 170
 171 static int orion5x_wdt_release(struct inode *inode, struct file *file)
 172 {
 173         if (test_bit(WDT_OK_TO_CLOSE, &wdt_status))
 174                 wdt_disable();
 175         else
 176                 printk(KERN_CRIT "WATCHDOG: Device closed unexpectedly - "
 177                                         "timer will not stop\n");
 178         clear_bit(WDT_IN_USE, &wdt_status);
 179         clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
 180
 181         return 0;
 182 }
 183
 184
 185 static const struct file_operations orion5x_wdt_fops = {
 186         .owner          = THIS_MODULE,
 187         .llseek         = no_llseek,
 188         .write          = orion5x_wdt_write,
 189         .unlocked_ioctl = orion5x_wdt_ioctl,
 190         .open           = orion5x_wdt_open,
 191         .release        = orion5x_wdt_release,
 192 };
 193
 194 static struct miscdevice orion5x_wdt_miscdev = {
 195         .minor          = WATCHDOG_MINOR,
 196         .name           = "watchdog",
 197         .fops           = &orion5x_wdt_fops,
 198 };
 199
 200 static int __init orion5x_wdt_init(void)
 201 {
 202         int ret;
 203
 204         ret = misc_register(&orion5x_wdt_miscdev);
 205         if (ret == 0)
 206                 printk("Orion5x Watchdog Timer: heartbeat %d sec\n",
 207                                                                 heartbeat);
 208
 209         return ret;
 210 }
 211
 212 static void __exit orion5x_wdt_exit(void)
 213 {
 214         misc_deregister(&orion5x_wdt_miscdev);
 215 }
 216
 217 module_init(orion5x_wdt_init);
 218 module_exit(orion5x_wdt_exit);
 219
 220 MODULE_AUTHOR("Sylver Bruneau <sylver.bruneau@googlemail.com>");
 221 MODULE_DESCRIPTION("Orion5x Processor Watchdog");
 222
 223 module_param(heartbeat, int, 0);
 224 MODULE_PARM_DESC(heartbeat, "Watchdog heartbeat in seconds (default is "
 225                                         __MODULE_STRING(WDT_MAX_DURATION) ")");
 226
 227 module_param(nowayout, int, 0);
 228 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started");
 229
 230 MODULE_LICENSE("GPL");
 231 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);