drivers/watchdog/mv64x60_wdt.c

   1 /*
   2  * mv64x60_wdt.c - MV64X60 (Marvell Discovery) watchdog userspace interface
   3  *
   4  * Author: James Chapman <jchapman@katalix.com>
   5  *
   6  * Platform-specific setup code should configure the dog to generate
   7  * interrupt or reset as required.  This code only enables/disables
   8  * and services the watchdog.
   9  *
  10  * Derived from mpc8xx_wdt.c, with the following copyright.
  11  *
  12  * 2002 (c) Florian Schirmer <jolt@tuxbox.org> This file is licensed under
  13  * the terms of the GNU General Public License version 2. This program
  14  * is licensed "as is" without any warranty of any kind, whether express
  15  * or implied.
  16  */
  17
  18 #include <linux/fs.h>
  19 #include <linux/init.h>
  20 #include <linux/kernel.h>
  21 #include <linux/miscdevice.h>
  22 #include <linux/module.h>
  23 #include <linux/watchdog.h>
  24 #include <linux/platform_device.h>
  25
  26 #include <linux/mv643xx.h>
  27 #include <asm/uaccess.h>
  28 #include <asm/io.h>
  29
  30 #define MV64x60_WDT_WDC_OFFSET  0
  31
  32 /*
  33  * The watchdog configuration register contains a pair of 2-bit fields,
  34  *   1.  a reload field, bits 27-26, which triggers a reload of
  35  *       the countdown register, and
  36  *   2.  an enable field, bits 25-24, which toggles between
  37  *       enabling and disabling the watchdog timer.
  38  * Bit 31 is a read-only field which indicates whether the
  39  * watchdog timer is currently enabled.
  40  *
  41  * The low 24 bits contain the timer reload value.
  42  */
  43 #define MV64x60_WDC_ENABLE_SHIFT        24
  44 #define MV64x60_WDC_SERVICE_SHIFT       26
  45 #define MV64x60_WDC_ENABLED_SHIFT       31
  46
  47 #define MV64x60_WDC_ENABLED_TRUE        1
  48 #define MV64x60_WDC_ENABLED_FALSE       0
  49
  50 /* Flags bits */
  51 #define MV64x60_WDOG_FLAG_OPENED        0
  52
  53 static unsigned long wdt_flags;
  54 static int wdt_status;
  55 static void __iomem *mv64x60_wdt_regs;
  56 static int mv64x60_wdt_timeout;
  57 static int mv64x60_wdt_count;
  58 static unsigned int bus_clk;
  59 static char expect_close;
  60 static DEFINE_SPINLOCK(mv64x60_wdt_spinlock);
  61
  62 static int nowayout = WATCHDOG_NOWAYOUT;
  63 module_param(nowayout, int, 0);
  64 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  65
  66 static int mv64x60_wdt_toggle_wdc(int enabled_predicate, int field_shift)
  67 {
  68         u32 data;
  69         u32 enabled;
  70         int ret = 0;
  71
  72         spin_lock(&mv64x60_wdt_spinlock);
  73         data = readl(mv64x60_wdt_regs + MV64x60_WDT_WDC_OFFSET);
  74         enabled = (data >> MV64x60_WDC_ENABLED_SHIFT) & 1;
  75
  76         /* only toggle the requested field if enabled state matches predicate */
  77         if ((enabled ^ enabled_predicate) == 0) {
  78                 /* We write a 1, then a 2 -- to the appropriate field */
  79                 data = (1 << field_shift) | mv64x60_wdt_count;
  80                 writel(data, mv64x60_wdt_regs + MV64x60_WDT_WDC_OFFSET);
  81
  82                 data = (2 << field_shift) | mv64x60_wdt_count;
  83                 writel(data, mv64x60_wdt_regs + MV64x60_WDT_WDC_OFFSET);
  84                 ret = 1;
  85         }
  86         spin_unlock(&mv64x60_wdt_spinlock);
  87
  88         return ret;
  89 }
  90
  91 static void mv64x60_wdt_service(void)
  92 {
  93         mv64x60_wdt_toggle_wdc(MV64x60_WDC_ENABLED_TRUE,
  94                                MV64x60_WDC_SERVICE_SHIFT);
  95 }
  96
  97 static void mv64x60_wdt_handler_enable(void)
  98 {
  99         if (mv64x60_wdt_toggle_wdc(MV64x60_WDC_ENABLED_FALSE,
 100                                    MV64x60_WDC_ENABLE_SHIFT)) {
 101                 mv64x60_wdt_service();
 102                 printk(KERN_NOTICE "mv64x60_wdt: watchdog activated\n");
 103         }
 104 }
 105
 106 static void mv64x60_wdt_handler_disable(void)
 107 {
 108         if (mv64x60_wdt_toggle_wdc(MV64x60_WDC_ENABLED_TRUE,
 109                                    MV64x60_WDC_ENABLE_SHIFT))
 110                 printk(KERN_NOTICE "mv64x60_wdt: watchdog deactivated\n");
 111 }
 112
 113 static void mv64x60_wdt_set_timeout(unsigned int timeout)
 114 {
 115         /* maximum bus cycle count is 0xFFFFFFFF */
 116         if (timeout > 0xFFFFFFFF / bus_clk)
 117                 timeout = 0xFFFFFFFF / bus_clk;
 118
 119         mv64x60_wdt_count = timeout * bus_clk >> 8;
 120         mv64x60_wdt_timeout = timeout;
 121 }
 122
 123 static int mv64x60_wdt_open(struct inode *inode, struct file *file)
 124 {
 125         if (test_and_set_bit(MV64x60_WDOG_FLAG_OPENED, &wdt_flags))
 126                 return -EBUSY;
 127
 128         if (nowayout)
 129                 __module_get(THIS_MODULE);
 130
 131         mv64x60_wdt_handler_enable();
 132
 133         return nonseekable_open(inode, file);
 134 }
 135
 136 static int mv64x60_wdt_release(struct inode *inode, struct file *file)
 137 {
 138         if (expect_close == 42)
 139                 mv64x60_wdt_handler_disable();
 140         else {
 141                 printk(KERN_CRIT
 142                        "mv64x60_wdt: unexpected close, not stopping timer!\n");
 143                 mv64x60_wdt_service();
 144         }
 145         expect_close = 0;
 146
 147         clear_bit(MV64x60_WDOG_FLAG_OPENED, &wdt_flags);
 148
 149         return 0;
 150 }
 151
 152 static ssize_t mv64x60_wdt_write(struct file *file, const char __user *data,
 153                                  size_t len, loff_t * ppos)
 154 {
 155         if (len) {
 156                 if (!nowayout) {
 157                         size_t i;
 158
 159                         expect_close = 0;
 160
 161                         for (i = 0; i != len; i++) {
 162                                 char c;
 163                                 if(get_user(c, data + i))
 164                                         return -EFAULT;
 165                                 if (c == 'V')
 166                                         expect_close = 42;
 167                         }
 168                 }
 169                 mv64x60_wdt_service();
 170         }
 171
 172         return len;
 173 }
 174
 175 static int mv64x60_wdt_ioctl(struct inode *inode, struct file *file,
 176                              unsigned int cmd, unsigned long arg)
 177 {
 178         int timeout;
 179         int options;
 180         void __user *argp = (void __user *)arg;
 181         static struct watchdog_info info = {
 182                 .options =      WDIOF_SETTIMEOUT        |
 183                                 WDIOF_MAGICCLOSE        |
 184                                 WDIOF_KEEPALIVEPING,
 185                 .firmware_version = 0,
 186                 .identity = "MV64x60 watchdog",
 187         };
 188
 189         switch (cmd) {
 190         case WDIOC_GETSUPPORT:
 191                 if (copy_to_user(argp, &info, sizeof(info)))
 192                         return -EFAULT;
 193                 break;
 194
 195         case WDIOC_GETSTATUS:
 196         case WDIOC_GETBOOTSTATUS:
 197                 if (put_user(wdt_status, (int __user *)argp))
 198                         return -EFAULT;
 199                 wdt_status &= ~WDIOF_KEEPALIVEPING;
 200                 break;
 201
 202         case WDIOC_GETTEMP:
 203                 return -EOPNOTSUPP;
 204
 205         case WDIOC_SETOPTIONS:
 206                 if (get_user(options, (int __user *)argp))
 207                         return -EFAULT;
 208
 209                 if (options & WDIOS_DISABLECARD)
 210                         mv64x60_wdt_handler_disable();
 211
 212                 if (options & WDIOS_ENABLECARD)
 213                         mv64x60_wdt_handler_enable();
 214                 break;
 215
 216         case WDIOC_KEEPALIVE:
 217                 mv64x60_wdt_service();
 218                 wdt_status |= WDIOF_KEEPALIVEPING;
 219                 break;
 220
 221         case WDIOC_SETTIMEOUT:
 222                 if (get_user(timeout, (int __user *)argp))
 223                         return -EFAULT;
 224                 mv64x60_wdt_set_timeout(timeout);
 225                 /* Fall through */
 226
 227         case WDIOC_GETTIMEOUT:
 228                 if (put_user(mv64x60_wdt_timeout, (int __user *)argp))
 229                         return -EFAULT;
 230                 break;
 231
 232         default:
 233                 return -ENOTTY;
 234         }
 235
 236         return 0;
 237 }
 238
 239 static const struct file_operations mv64x60_wdt_fops = {
 240         .owner = THIS_MODULE,
 241         .llseek = no_llseek,
 242         .write = mv64x60_wdt_write,
 243         .ioctl = mv64x60_wdt_ioctl,
 244         .open = mv64x60_wdt_open,
 245         .release = mv64x60_wdt_release,
 246 };
 247
 248 static struct miscdevice mv64x60_wdt_miscdev = {
 249         .minor = WATCHDOG_MINOR,
 250         .name = "watchdog",
 251         .fops = &mv64x60_wdt_fops,
 252 };
 253
 254 static int __devinit mv64x60_wdt_probe(struct platform_device *dev)
 255 {
 256         struct mv64x60_wdt_pdata *pdata = dev->dev.platform_data;
 257         struct resource *r;
 258         int timeout = 10;
 259
 260         bus_clk = 133;                  /* in MHz */
 261         if (pdata) {
 262                 timeout = pdata->timeout;
 263                 bus_clk = pdata->bus_clk;
 264         }
 265
 266         /* Since bus_clk is truncated MHz, actual frequency could be
 267          * up to 1MHz higher.  Round up, since it's better to time out
 268          * too late than too soon.
 269          */
 270         bus_clk++;
 271         bus_clk *= 1000000;             /* convert to Hz */
 272
 273         r = platform_get_resource(dev, IORESOURCE_MEM, 0);
 274         if (!r)
 275                 return -ENODEV;
 276
 277         mv64x60_wdt_regs = ioremap(r->start, r->end - r->start + 1);
 278         if (mv64x60_wdt_regs == NULL)
 279                 return -ENOMEM;
 280
 281         mv64x60_wdt_set_timeout(timeout);
 282
 283         mv64x60_wdt_handler_disable();  /* in case timer was already running */
 284
 285         return misc_register(&mv64x60_wdt_miscdev);
 286 }
 287
 288 static int __devexit mv64x60_wdt_remove(struct platform_device *dev)
 289 {
 290         misc_deregister(&mv64x60_wdt_miscdev);
 291
 292         mv64x60_wdt_handler_disable();
 293
 294         iounmap(mv64x60_wdt_regs);
 295
 296         return 0;
 297 }
 298
 299 static struct platform_driver mv64x60_wdt_driver = {
 300         .probe = mv64x60_wdt_probe,
 301         .remove = __devexit_p(mv64x60_wdt_remove),
 302         .driver = {
 303                 .owner = THIS_MODULE,
 304                 .name = MV64x60_WDT_NAME,
 305         },
 306 };
 307
 308 static int __init mv64x60_wdt_init(void)
 309 {
 310         printk(KERN_INFO "MV64x60 watchdog driver\n");
 311
 312         return platform_driver_register(&mv64x60_wdt_driver);
 313 }
 314
 315 static void __exit mv64x60_wdt_exit(void)
 316 {
 317         platform_driver_unregister(&mv64x60_wdt_driver);
 318 }
 319
 320 module_init(mv64x60_wdt_init);
 321 module_exit(mv64x60_wdt_exit);
 322
 323 MODULE_AUTHOR("James Chapman <jchapman@katalix.com>");
 324 MODULE_DESCRIPTION("MV64x60 watchdog driver");
 325 MODULE_LICENSE("GPL");
 326 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);