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 <asm/diag.h>
  33 #include <linux/io.h>
  34 #include <linux/uaccess.h>
  35
  36 #define MAX_CMDLEN 240
  37 #define DEFAULT_CMD "SYSTEM RESTART"
  38
  39 #define MIN_INTERVAL 15     /* Minimal time supported by diag88 */
  40 #define MAX_INTERVAL 3600   /* One hour should be enough - pure estimation */
  41
  42 #define WDT_DEFAULT_TIMEOUT 30
  43
  44 /* Function codes - init, change, cancel */
  45 #define WDT_FUNC_INIT 0
  46 #define WDT_FUNC_CHANGE 1
  47 #define WDT_FUNC_CANCEL 2
  48 #define WDT_FUNC_CONCEAL 0x80000000
  49
  50 /* Action codes for LPAR watchdog */
  51 #define LPARWDT_RESTART 0
  52
  53 static char wdt_cmd[MAX_CMDLEN] = DEFAULT_CMD;
  54 static bool conceal_on;
  55 static bool nowayout_info = WATCHDOG_NOWAYOUT;
  56
  57 MODULE_LICENSE("GPL");
  58 MODULE_AUTHOR("Arnd Bergmann <arndb@de.ibm.com>");
  59 MODULE_AUTHOR("Philipp Hachtmann <phacht@de.ibm.com>");
  60
  61 MODULE_DESCRIPTION("System z diag288  Watchdog Timer");
  62
  63 module_param_string(cmd, wdt_cmd, MAX_CMDLEN, 0644);
  64 MODULE_PARM_DESC(cmd, "CP command that is run when the watchdog triggers (z/VM only)");
  65
  66 module_param_named(conceal, conceal_on, bool, 0644);
  67 MODULE_PARM_DESC(conceal, "Enable the CONCEAL CP option while the watchdog is active (z/VM only)");
  68
  69 module_param_named(nowayout, nowayout_info, bool, 0444);
  70 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default = CONFIG_WATCHDOG_NOWAYOUT)");
  71
  72 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
  73 MODULE_ALIAS("vmwatchdog");
  74
  75 static int __diag288(unsigned int func, unsigned int timeout,
  76                      unsigned long action, unsigned int len)
  77 {
  78         register unsigned long __func asm("2") = func;
  79         register unsigned long __timeout asm("3") = timeout;
  80         register unsigned long __action asm("4") = action;
  81         register unsigned long __len asm("5") = len;
  82         int err;
  83
  84         err = -EINVAL;
  85         asm volatile(
  86                 "       diag    %1, %3, 0x288\n"
  87                 "0:     la      %0, 0\n"
  88                 "1:\n"
  89                 EX_TABLE(0b, 1b)
  90                 : "+d" (err) : "d"(__func), "d"(__timeout),
  91                   "d"(__action), "d"(__len) : "1", "cc");
  92         return err;
  93 }
  94
  95 static int __diag288_vm(unsigned int  func, unsigned int timeout,
  96                         char *cmd, size_t len)
  97 {
  98         diag_stat_inc(DIAG_STAT_X288);
  99         return __diag288(func, timeout, virt_to_phys(cmd), len);
 100 }
 101
 102 static int __diag288_lpar(unsigned int func, unsigned int timeout,
 103                           unsigned long action)
 104 {
 105         diag_stat_inc(DIAG_STAT_X288);
 106         return __diag288(func, timeout, action, 0);
 107 }
 108
 109 static unsigned long wdt_status;
 110
 111 #define DIAG_WDOG_BUSY  0
 112
 113 static int wdt_start(struct watchdog_device *dev)
 114 {
 115         char *ebc_cmd;
 116         size_t len;
 117         int ret;
 118         unsigned int func;
 119
 120         if (test_and_set_bit(DIAG_WDOG_BUSY, &wdt_status))
 121                 return -EBUSY;
 122
 123         ret = -ENODEV;
 124
 125         if (MACHINE_IS_VM) {
 126                 ebc_cmd = kmalloc(MAX_CMDLEN, GFP_KERNEL);
 127                 if (!ebc_cmd) {
 128                         clear_bit(DIAG_WDOG_BUSY, &wdt_status);
 129                         return -ENOMEM;
 130                 }
 131                 len = strlcpy(ebc_cmd, wdt_cmd, MAX_CMDLEN);
 132                 ASCEBC(ebc_cmd, MAX_CMDLEN);
 133                 EBC_TOUPPER(ebc_cmd, MAX_CMDLEN);
 134
 135                 func = conceal_on ? (WDT_FUNC_INIT | WDT_FUNC_CONCEAL)
 136                         : WDT_FUNC_INIT;
 137                 ret = __diag288_vm(func, dev->timeout, ebc_cmd, len);
 138                 WARN_ON(ret != 0);
 139                 kfree(ebc_cmd);
 140         } else {
 141                 ret = __diag288_lpar(WDT_FUNC_INIT,
 142                                      dev->timeout, LPARWDT_RESTART);
 143         }
 144
 145         if (ret) {
 146                 pr_err("The watchdog cannot be activated\n");
 147                 clear_bit(DIAG_WDOG_BUSY, &wdt_status);
 148                 return ret;
 149         }
 150         return 0;
 151 }
 152
 153 static int wdt_stop(struct watchdog_device *dev)
 154 {
 155         int ret;
 156
 157         diag_stat_inc(DIAG_STAT_X288);
 158         ret = __diag288(WDT_FUNC_CANCEL, 0, 0, 0);
 159
 160         clear_bit(DIAG_WDOG_BUSY, &wdt_status);
 161
 162         return ret;
 163 }
 164
 165 static int wdt_ping(struct watchdog_device *dev)
 166 {
 167         char *ebc_cmd;
 168         size_t len;
 169         int ret;
 170         unsigned int func;
 171
 172         ret = -ENODEV;
 173
 174         if (MACHINE_IS_VM) {
 175                 ebc_cmd = kmalloc(MAX_CMDLEN, GFP_KERNEL);
 176                 if (!ebc_cmd)
 177                         return -ENOMEM;
 178                 len = strlcpy(ebc_cmd, wdt_cmd, MAX_CMDLEN);
 179                 ASCEBC(ebc_cmd, MAX_CMDLEN);
 180                 EBC_TOUPPER(ebc_cmd, MAX_CMDLEN);
 181
 182                 /*
 183                  * It seems to be ok to z/VM to use the init function to
 184                  * retrigger the watchdog. On LPAR WDT_FUNC_CHANGE must
 185                  * be used when the watchdog is running.
 186                  */
 187                 func = conceal_on ? (WDT_FUNC_INIT | WDT_FUNC_CONCEAL)
 188                         : WDT_FUNC_INIT;
 189
 190                 ret = __diag288_vm(func, dev->timeout, ebc_cmd, len);
 191                 WARN_ON(ret != 0);
 192                 kfree(ebc_cmd);
 193         } else {
 194                 ret = __diag288_lpar(WDT_FUNC_CHANGE, dev->timeout, 0);
 195         }
 196
 197         if (ret)
 198                 pr_err("The watchdog timer cannot be started or reset\n");
 199         return ret;
 200 }
 201
 202 static int wdt_set_timeout(struct watchdog_device * dev, unsigned int new_to)
 203 {
 204         dev->timeout = new_to;
 205         return wdt_ping(dev);
 206 }
 207
 208 static const struct watchdog_ops wdt_ops = {
 209         .owner = THIS_MODULE,
 210         .start = wdt_start,
 211         .stop = wdt_stop,
 212         .ping = wdt_ping,
 213         .set_timeout = wdt_set_timeout,
 214 };
 215
 216 static const struct watchdog_info wdt_info = {
 217         .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
 218         .firmware_version = 0,
 219         .identity = "z Watchdog",
 220 };
 221
 222 static struct watchdog_device wdt_dev = {
 223         .parent = NULL,
 224         .info = &wdt_info,
 225         .ops = &wdt_ops,
 226         .bootstatus = 0,
 227         .timeout = WDT_DEFAULT_TIMEOUT,
 228         .min_timeout = MIN_INTERVAL,
 229         .max_timeout = MAX_INTERVAL,
 230 };
 231
 232 /*
 233  * It makes no sense to go into suspend while the watchdog is running.
 234  * Depending on the memory size, the watchdog might trigger, while we
 235  * are still saving the memory.
 236  */
 237 static int wdt_suspend(void)
 238 {
 239         if (test_and_set_bit(DIAG_WDOG_BUSY, &wdt_status)) {
 240                 pr_err("Linux cannot be suspended while the watchdog is in use\n");
 241                 return notifier_from_errno(-EBUSY);
 242         }
 243         return NOTIFY_DONE;
 244 }
 245
 246 static int wdt_resume(void)
 247 {
 248         clear_bit(DIAG_WDOG_BUSY, &wdt_status);
 249         return NOTIFY_DONE;
 250 }
 251
 252 static int wdt_power_event(struct notifier_block *this, unsigned long event,
 253                            void *ptr)
 254 {
 255         switch (event) {
 256         case PM_POST_HIBERNATION:
 257         case PM_POST_SUSPEND:
 258                 return wdt_resume();
 259         case PM_HIBERNATION_PREPARE:
 260         case PM_SUSPEND_PREPARE:
 261                 return wdt_suspend();
 262         default:
 263                 return NOTIFY_DONE;
 264         }
 265 }
 266
 267 static struct notifier_block wdt_power_notifier = {
 268         .notifier_call = wdt_power_event,
 269 };
 270
 271 static int __init diag288_init(void)
 272 {
 273         int ret;
 274         char ebc_begin[] = {
 275                 194, 197, 199, 201, 213
 276         };
 277
 278         watchdog_set_nowayout(&wdt_dev, nowayout_info);
 279
 280         if (MACHINE_IS_VM) {
 281                 if (__diag288_vm(WDT_FUNC_INIT, 15,
 282                                  ebc_begin, sizeof(ebc_begin)) != 0) {
 283                         pr_err("The watchdog cannot be initialized\n");
 284                         return -EINVAL;
 285                 }
 286         } else {
 287                 if (__diag288_lpar(WDT_FUNC_INIT, 30, LPARWDT_RESTART)) {
 288                         pr_err("The watchdog cannot be initialized\n");
 289                         return -EINVAL;
 290                 }
 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);