drivers/watchdog/diag288_wdt.c

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