drivers/watchdog/diag288_wdt.c

   1 /*
   2  * Watchdog driver for z/VM and LPAR using the diag 288 interface.
   3  *
   4  * Under z/VM, expiration of the watchdog will send a "system restart" command
   5  * to CP.
   6  *
   7  * The command can be altered using the module parameter "cmd". This is
   8  * not recommended because it's only supported on z/VM but not whith LPAR.
   9  *
  10  * On LPAR, the watchdog will always trigger a system restart. the module
  11  * paramter cmd is meaningless here.
  12  *
  13  *
  14  * Copyright IBM Corp. 2004, 2013
  15  * Author(s): Arnd Bergmann (arndb@de.ibm.com)
  16  *            Philipp Hachtmann (phacht@de.ibm.com)
  17  *
  18  */
  19
  20 #define KMSG_COMPONENT "diag288_wdt"
  21 #define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
  22
  23 #include <linux/init.h>
  24 #include <linux/kernel.h>
  25 #include <linux/module.h>
  26 #include <linux/moduleparam.h>
  27 #include <linux/slab.h>
  28 #include <linux/miscdevice.h>
  29 #include <linux/watchdog.h>
  30 #include <linux/suspend.h>
  31 #include <asm/ebcdic.h>
  32 #include <linux/io.h>
  33 #include <linux/uaccess.h>
  34
  35 #define MAX_CMDLEN 240
  36 #define DEFAULT_CMD "SYSTEM RESTART"
  37
  38 #define MIN_INTERVAL 15     /* Minimal time supported by diag88 */
  39 #define MAX_INTERVAL 3600   /* One hour should be enough - pure estimation */
  40
  41 #define WDT_DEFAULT_TIMEOUT 30
  42
  43 /* Function codes - init, change, cancel */
  44 #define WDT_FUNC_INIT 0
  45 #define WDT_FUNC_CHANGE 1
  46 #define WDT_FUNC_CANCEL 2
  47 #define WDT_FUNC_CONCEAL 0x80000000
  48
  49 /* Action codes for LPAR watchdog */
  50 #define LPARWDT_RESTART 0
  51
  52 static char wdt_cmd[MAX_CMDLEN] = DEFAULT_CMD;
  53 static bool conceal_on;
  54 static bool nowayout_info = WATCHDOG_NOWAYOUT;
  55
  56 MODULE_LICENSE("GPL");
  57 MODULE_AUTHOR("Arnd Bergmann <arndb@de.ibm.com>");
  58 MODULE_AUTHOR("Philipp Hachtmann <phacht@de.ibm.com>");
  59
  60 MODULE_DESCRIPTION("System z diag288  Watchdog Timer");
  61
  62 module_param_string(cmd, wdt_cmd, MAX_CMDLEN, 0644);
  63 MODULE_PARM_DESC(cmd, "CP command that is run when the watchdog triggers (z/VM only)");
  64
  65 module_param_named(conceal, conceal_on, bool, 0644);
  66 MODULE_PARM_DESC(conceal, "Enable the CONCEAL CP option while the watchdog is active (z/VM only)");
  67
  68 module_param_named(nowayout, nowayout_info, bool, 0444);
  69 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default = CONFIG_WATCHDOG_NOWAYOUT)");
  70
  71 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
  72 MODULE_ALIAS("vmwatchdog");
  73
  74 static int __diag288(unsigned int func, unsigned int timeout,
  75                      unsigned long action, unsigned int len)
  76 {
  77         register unsigned long __func asm("2") = func;
  78         register unsigned long __timeout asm("3") = timeout;
  79         register unsigned long __action asm("4") = action;
  80         register unsigned long __len asm("5") = len;
  81         int err;
  82
  83         err = -EINVAL;
  84         asm volatile(
  85                 "       diag    %1, %3, 0x288\n"
  86                 "0:     la      %0, 0\n"
  87                 "1:\n"
  88                 EX_TABLE(0b, 1b)
  89                 : "+d" (err) : "d"(__func), "d"(__timeout),
  90                   "d"(__action), "d"(__len) : "1", "cc");
  91         return err;
  92 }
  93
  94 static int __diag288_vm(unsigned int  func, unsigned int timeout,
  95                         char *cmd, size_t len)
  96 {
  97         return __diag288(func, timeout, virt_to_phys(cmd), len);
  98 }
  99
 100 static int __diag288_lpar(unsigned int func, unsigned int timeout,
 101                           unsigned long action)
 102 {
 103         return __diag288(func, timeout, action, 0);
 104 }
 105
 106 static int wdt_start(struct watchdog_device *dev)
 107 {
 108         char *ebc_cmd;
 109         size_t len;
 110         int ret;
 111         unsigned int func;
 112
 113         ret = -ENODEV;
 114
 115         if (MACHINE_IS_VM) {
 116                 ebc_cmd = kmalloc(MAX_CMDLEN, GFP_KERNEL);
 117                 if (!ebc_cmd)
 118                         return -ENOMEM;
 119                 len = strlcpy(ebc_cmd, wdt_cmd, MAX_CMDLEN);
 120                 ASCEBC(ebc_cmd, MAX_CMDLEN);
 121                 EBC_TOUPPER(ebc_cmd, MAX_CMDLEN);
 122
 123                 func = conceal_on ? (WDT_FUNC_INIT | WDT_FUNC_CONCEAL)
 124                         : WDT_FUNC_INIT;
 125                 ret = __diag288_vm(func, dev->timeout, ebc_cmd, len);
 126                 WARN_ON(ret != 0);
 127                 kfree(ebc_cmd);
 128         }
 129
 130         if (MACHINE_IS_LPAR) {
 131                 ret = __diag288_lpar(WDT_FUNC_INIT,
 132                                      dev->timeout, LPARWDT_RESTART);
 133         }
 134
 135         if (ret) {
 136                 pr_err("The watchdog cannot be activated\n");
 137                 return ret;
 138         }
 139         pr_info("The watchdog was activated\n");
 140         return 0;
 141 }
 142
 143 static int wdt_stop(struct watchdog_device *dev)
 144 {
 145         int ret;
 146
 147         ret = __diag288(WDT_FUNC_CANCEL, 0, 0, 0);
 148         pr_info("The watchdog was deactivated\n");
 149         return ret;
 150 }
 151
 152 static int wdt_ping(struct watchdog_device *dev)
 153 {
 154         char *ebc_cmd;
 155         size_t len;
 156         int ret;
 157         unsigned int func;
 158
 159         ret = -ENODEV;
 160
 161         if (MACHINE_IS_VM) {
 162                 ebc_cmd = kmalloc(MAX_CMDLEN, GFP_KERNEL);
 163                 if (!ebc_cmd)
 164                         return -ENOMEM;
 165                 len = strlcpy(ebc_cmd, wdt_cmd, MAX_CMDLEN);
 166                 ASCEBC(ebc_cmd, MAX_CMDLEN);
 167                 EBC_TOUPPER(ebc_cmd, MAX_CMDLEN);
 168
 169                 /*
 170                  * It seems to be ok to z/VM to use the init function to
 171                  * retrigger the watchdog. On LPAR WDT_FUNC_CHANGE must
 172                  * be used when the watchdog is running.
 173                  */
 174                 func = conceal_on ? (WDT_FUNC_INIT | WDT_FUNC_CONCEAL)
 175                         : WDT_FUNC_INIT;
 176
 177                 ret = __diag288_vm(func, dev->timeout, ebc_cmd, len);
 178                 WARN_ON(ret != 0);
 179                 kfree(ebc_cmd);
 180         }
 181
 182         if (MACHINE_IS_LPAR)
 183                 ret = __diag288_lpar(WDT_FUNC_CHANGE, dev->timeout, 0);
 184
 185         if (ret)
 186                 pr_err("The watchdog timer cannot be started or reset\n");
 187         return ret;
 188 }
 189
 190 static int wdt_set_timeout(struct watchdog_device * dev, unsigned int new_to)
 191 {
 192         dev->timeout = new_to;
 193         return wdt_ping(dev);
 194 }
 195
 196 static struct watchdog_ops wdt_ops = {
 197         .owner = THIS_MODULE,
 198         .start = wdt_start,
 199         .stop = wdt_stop,
 200         .ping = wdt_ping,
 201         .set_timeout = wdt_set_timeout,
 202 };
 203
 204 static struct watchdog_info wdt_info = {
 205         .options = WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE,
 206         .firmware_version = 0,
 207         .identity = "z Watchdog",
 208 };
 209
 210 static struct watchdog_device wdt_dev = {
 211         .parent = NULL,
 212         .info = &wdt_info,
 213         .ops = &wdt_ops,
 214         .bootstatus = 0,
 215         .timeout = WDT_DEFAULT_TIMEOUT,
 216         .min_timeout = MIN_INTERVAL,
 217         .max_timeout = MAX_INTERVAL,
 218 };
 219
 220 /*
 221  * It makes no sense to go into suspend while the watchdog is running.
 222  * Depending on the memory size, the watchdog might trigger, while we
 223  * are still saving the memory.
 224  * We reuse the open flag to ensure that suspend and watchdog open are
 225  * exclusive operations
 226  */
 227 static int wdt_suspend(void)
 228 {
 229         if (test_and_set_bit(WDOG_DEV_OPEN, &wdt_dev.status)) {
 230                 pr_err("Linux cannot be suspended while the watchdog is in use\n");
 231                 return notifier_from_errno(-EBUSY);
 232         }
 233         if (test_bit(WDOG_ACTIVE, &wdt_dev.status)) {
 234                 clear_bit(WDOG_DEV_OPEN, &wdt_dev.status);
 235                 pr_err("Linux cannot be suspended while the watchdog is in use\n");
 236                 return notifier_from_errno(-EBUSY);
 237         }
 238         return NOTIFY_DONE;
 239 }
 240
 241 static int wdt_resume(void)
 242 {
 243         clear_bit(WDOG_DEV_OPEN, &wdt_dev.status);
 244         return NOTIFY_DONE;
 245 }
 246
 247 static int wdt_power_event(struct notifier_block *this, unsigned long event,
 248                            void *ptr)
 249 {
 250         switch (event) {
 251         case PM_POST_HIBERNATION:
 252         case PM_POST_SUSPEND:
 253                 return wdt_resume();
 254         case PM_HIBERNATION_PREPARE:
 255         case PM_SUSPEND_PREPARE:
 256                 return wdt_suspend();
 257         default:
 258                 return NOTIFY_DONE;
 259         }
 260 }
 261
 262 static struct notifier_block wdt_power_notifier = {
 263         .notifier_call = wdt_power_event,
 264 };
 265
 266 static int __init diag288_init(void)
 267 {
 268         int ret;
 269         char ebc_begin[] = {
 270                 194, 197, 199, 201, 213
 271         };
 272
 273         watchdog_set_nowayout(&wdt_dev, nowayout_info);
 274
 275         if (MACHINE_IS_VM) {
 276                 pr_info("The watchdog device driver detected a z/VM environment\n");
 277                 if (__diag288_vm(WDT_FUNC_INIT, 15,
 278                                  ebc_begin, sizeof(ebc_begin)) != 0) {
 279                         pr_err("The watchdog cannot be initialized\n");
 280                         return -EINVAL;
 281                 }
 282         } else if (MACHINE_IS_LPAR) {
 283                 pr_info("The watchdog device driver detected an LPAR environment\n");
 284                 if (__diag288_lpar(WDT_FUNC_INIT, 30, LPARWDT_RESTART)) {
 285                         pr_err("The watchdog cannot be initialized\n");
 286                         return -EINVAL;
 287                 }
 288         } else {
 289                 pr_err("Linux runs in an environment that does not support the diag288 watchdog\n");
 290                 return -ENODEV;
 291         }
 292
 293         if (__diag288_lpar(WDT_FUNC_CANCEL, 0, 0)) {
 294                 pr_err("The watchdog cannot be deactivated\n");
 295                 return -EINVAL;
 296         }
 297
 298         ret = register_pm_notifier(&wdt_power_notifier);
 299         if (ret)
 300                 return ret;
 301
 302         ret = watchdog_register_device(&wdt_dev);
 303         if (ret)
 304                 unregister_pm_notifier(&wdt_power_notifier);
 305
 306         return ret;
 307 }
 308
 309 static void __exit diag288_exit(void)
 310 {
 311         watchdog_unregister_device(&wdt_dev);
 312         unregister_pm_notifier(&wdt_power_notifier);
 313 }
 314
 315 module_init(diag288_init);
 316 module_exit(diag288_exit);