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