linux/drivers/watchdog/diag288_wdt.c
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   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
  53static char wdt_cmd[MAX_CMDLEN] = DEFAULT_CMD;
  54static bool conceal_on;
  55static bool nowayout_info = WATCHDOG_NOWAYOUT;
  56
  57MODULE_LICENSE("GPL");
  58MODULE_AUTHOR("Arnd Bergmann <arndb@de.ibm.com>");
  59MODULE_AUTHOR("Philipp Hachtmann <phacht@de.ibm.com>");
  60
  61MODULE_DESCRIPTION("System z diag288  Watchdog Timer");
  62
  63module_param_string(cmd, wdt_cmd, MAX_CMDLEN, 0644);
  64MODULE_PARM_DESC(cmd, "CP command that is run when the watchdog triggers (z/VM only)");
  65
  66module_param_named(conceal, conceal_on, bool, 0644);
  67MODULE_PARM_DESC(conceal, "Enable the CONCEAL CP option while the watchdog is active (z/VM only)");
  68
  69module_param_named(nowayout, nowayout_info, bool, 0444);
  70MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default = CONFIG_WATCHDOG_NOWAYOUT)");
  71
  72MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
  73MODULE_ALIAS("vmwatchdog");
  74
  75static 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
  95static 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
 102static 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
 109static unsigned long wdt_status;
 110
 111#define DIAG_WDOG_BUSY  0
 112
 113static 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
 153static 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
 165static 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
 202static 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
 208static 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
 216static const struct watchdog_info wdt_info = {
 217        .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
 218        .firmware_version = 0,
 219        .identity = "z Watchdog",
 220};
 221
 222static 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 */
 237static 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
 246static int wdt_resume(void)
 247{
 248        clear_bit(DIAG_WDOG_BUSY, &wdt_status);
 249        return NOTIFY_DONE;
 250}
 251
 252static 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
 267static struct notifier_block wdt_power_notifier = {
 268        .notifier_call = wdt_power_event,
 269};
 270
 271static 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
 309static void __exit diag288_exit(void)
 310{
 311        watchdog_unregister_device(&wdt_dev);
 312        unregister_pm_notifier(&wdt_power_notifier);
 313}
 314
 315module_init(diag288_init);
 316module_exit(diag288_exit);
 317