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 int wdt_start(struct watchdog_device *dev)
 110 {
 111         char *ebc_cmd;
 112         size_t len;
 113         int ret;
 114         unsigned int func;
 115
 116         ret = -ENODEV;
 117
 118         if (MACHINE_IS_VM) {
 119                 ebc_cmd = kmalloc(MAX_CMDLEN, GFP_KERNEL);
 120                 if (!ebc_cmd)
 121                         return -ENOMEM;
 122                 len = strlcpy(ebc_cmd, wdt_cmd, MAX_CMDLEN);
 123                 ASCEBC(ebc_cmd, MAX_CMDLEN);
 124                 EBC_TOUPPER(ebc_cmd, MAX_CMDLEN);
 125
 126                 func = conceal_on ? (WDT_FUNC_INIT | WDT_FUNC_CONCEAL)
 127                         : WDT_FUNC_INIT;
 128                 ret = __diag288_vm(func, dev->timeout, ebc_cmd, len);
 129                 WARN_ON(ret != 0);
 130                 kfree(ebc_cmd);
 131         } else {
 132                 ret = __diag288_lpar(WDT_FUNC_INIT,
 133                                      dev->timeout, LPARWDT_RESTART);
 134         }
 135
 136         if (ret) {
 137                 pr_err("The watchdog cannot be activated\n");
 138                 return ret;
 139         }
 140         return 0;
 141 }
 142
 143 static int wdt_stop(struct watchdog_device *dev)
 144 {
 145         int ret;
 146
 147         diag_stat_inc(DIAG_STAT_X288);
 148         ret = __diag288(WDT_FUNC_CANCEL, 0, 0, 0);
 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         } else {
 181                 ret = __diag288_lpar(WDT_FUNC_CHANGE, dev->timeout, 0);
 182         }
 183
 184         if (ret)
 185                 pr_err("The watchdog timer cannot be started or reset\n");
 186         return ret;
 187 }
 188
 189 static int wdt_set_timeout(struct watchdog_device * dev, unsigned int new_to)
 190 {
 191         dev->timeout = new_to;
 192         return wdt_ping(dev);
 193 }
 194
 195 static struct watchdog_ops wdt_ops = {
 196         .owner = THIS_MODULE,
 197         .start = wdt_start,
 198         .stop = wdt_stop,
 199         .ping = wdt_ping,
 200         .set_timeout = wdt_set_timeout,
 201 };
 202
 203 static struct watchdog_info wdt_info = {
 204         .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
 205         .firmware_version = 0,
 206         .identity = "z Watchdog",
 207 };
 208
 209 static struct watchdog_device wdt_dev = {
 210         .parent = NULL,
 211         .info = &wdt_info,
 212         .ops = &wdt_ops,
 213         .bootstatus = 0,
 214         .timeout = WDT_DEFAULT_TIMEOUT,
 215         .min_timeout = MIN_INTERVAL,
 216         .max_timeout = MAX_INTERVAL,
 217 };
 218
 219 /*
 220  * It makes no sense to go into suspend while the watchdog is running.
 221  * Depending on the memory size, the watchdog might trigger, while we
 222  * are still saving the memory.
 223  * We reuse the open flag to ensure that suspend and watchdog open are
 224  * exclusive operations
 225  */
 226 static int wdt_suspend(void)
 227 {
 228         if (test_and_set_bit(WDOG_DEV_OPEN, &wdt_dev.status)) {
 229                 pr_err("Linux cannot be suspended while the watchdog is in use\n");
 230                 return notifier_from_errno(-EBUSY);
 231         }
 232         if (test_bit(WDOG_ACTIVE, &wdt_dev.status)) {
 233                 clear_bit(WDOG_DEV_OPEN, &wdt_dev.status);
 234                 pr_err("Linux cannot be suspended while the watchdog is in use\n");
 235                 return notifier_from_errno(-EBUSY);
 236         }
 237         return NOTIFY_DONE;
 238 }
 239
 240 static int wdt_resume(void)
 241 {
 242         clear_bit(WDOG_DEV_OPEN, &wdt_dev.status);
 243         return NOTIFY_DONE;
 244 }
 245
 246 static int wdt_power_event(struct notifier_block *this, unsigned long event,
 247                            void *ptr)
 248 {
 249         switch (event) {
 250         case PM_POST_HIBERNATION:
 251         case PM_POST_SUSPEND:
 252                 return wdt_resume();
 253         case PM_HIBERNATION_PREPARE:
 254         case PM_SUSPEND_PREPARE:
 255                 return wdt_suspend();
 256         default:
 257                 return NOTIFY_DONE;
 258         }
 259 }
 260
 261 static struct notifier_block wdt_power_notifier = {
 262         .notifier_call = wdt_power_event,
 263 };
 264
 265 static int __init diag288_init(void)
 266 {
 267         int ret;
 268         char ebc_begin[] = {
 269                 194, 197, 199, 201, 213
 270         };
 271
 272         watchdog_set_nowayout(&wdt_dev, nowayout_info);
 273
 274         if (MACHINE_IS_VM) {
 275                 if (__diag288_vm(WDT_FUNC_INIT, 15,
 276                                  ebc_begin, sizeof(ebc_begin)) != 0) {
 277                         pr_err("The watchdog cannot be initialized\n");
 278                         return -EINVAL;
 279                 }
 280         } else {
 281                 if (__diag288_lpar(WDT_FUNC_INIT, 30, LPARWDT_RESTART)) {
 282                         pr_err("The watchdog cannot be initialized\n");
 283                         return -EINVAL;
 284                 }
 285         }
 286
 287         if (__diag288_lpar(WDT_FUNC_CANCEL, 0, 0)) {
 288                 pr_err("The watchdog cannot be deactivated\n");
 289                 return -EINVAL;
 290         }
 291
 292         ret = register_pm_notifier(&wdt_power_notifier);
 293         if (ret)
 294                 return ret;
 295
 296         ret = watchdog_register_device(&wdt_dev);
 297         if (ret)
 298                 unregister_pm_notifier(&wdt_power_notifier);
 299
 300         return ret;
 301 }
 302
 303 static void __exit diag288_exit(void)
 304 {
 305         watchdog_unregister_device(&wdt_dev);
 306         unregister_pm_notifier(&wdt_power_notifier);
 307 }
 308
 309 module_init(diag288_init);
 310 module_exit(diag288_exit);