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 } else { 129 ret = __diag288_lpar(WDT_FUNC_INIT, 130 dev->timeout, LPARWDT_RESTART); 131 } 132 133 if (ret) { 134 pr_err("The watchdog cannot be activated\n"); 135 return ret; 136 } 137 return 0; 138 } 139 140 static int wdt_stop(struct watchdog_device *dev) 141 { 142 int ret; 143 144 ret = __diag288(WDT_FUNC_CANCEL, 0, 0, 0); 145 return ret; 146 } 147 148 static int wdt_ping(struct watchdog_device *dev) 149 { 150 char *ebc_cmd; 151 size_t len; 152 int ret; 153 unsigned int func; 154 155 ret = -ENODEV; 156 157 if (MACHINE_IS_VM) { 158 ebc_cmd = kmalloc(MAX_CMDLEN, GFP_KERNEL); 159 if (!ebc_cmd) 160 return -ENOMEM; 161 len = strlcpy(ebc_cmd, wdt_cmd, MAX_CMDLEN); 162 ASCEBC(ebc_cmd, MAX_CMDLEN); 163 EBC_TOUPPER(ebc_cmd, MAX_CMDLEN); 164 165 /* 166 * It seems to be ok to z/VM to use the init function to 167 * retrigger the watchdog. On LPAR WDT_FUNC_CHANGE must 168 * be used when the watchdog is running. 169 */ 170 func = conceal_on ? (WDT_FUNC_INIT | WDT_FUNC_CONCEAL) 171 : WDT_FUNC_INIT; 172 173 ret = __diag288_vm(func, dev->timeout, ebc_cmd, len); 174 WARN_ON(ret != 0); 175 kfree(ebc_cmd); 176 } else { 177 ret = __diag288_lpar(WDT_FUNC_CHANGE, dev->timeout, 0); 178 } 179 180 if (ret) 181 pr_err("The watchdog timer cannot be started or reset\n"); 182 return ret; 183 } 184 185 static int wdt_set_timeout(struct watchdog_device * dev, unsigned int new_to) 186 { 187 dev->timeout = new_to; 188 return wdt_ping(dev); 189 } 190 191 static struct watchdog_ops wdt_ops = { 192 .owner = THIS_MODULE, 193 .start = wdt_start, 194 .stop = wdt_stop, 195 .ping = wdt_ping, 196 .set_timeout = wdt_set_timeout, 197 }; 198 199 static struct watchdog_info wdt_info = { 200 .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE, 201 .firmware_version = 0, 202 .identity = "z Watchdog", 203 }; 204 205 static struct watchdog_device wdt_dev = { 206 .parent = NULL, 207 .info = &wdt_info, 208 .ops = &wdt_ops, 209 .bootstatus = 0, 210 .timeout = WDT_DEFAULT_TIMEOUT, 211 .min_timeout = MIN_INTERVAL, 212 .max_timeout = MAX_INTERVAL, 213 }; 214 215 /* 216 * It makes no sense to go into suspend while the watchdog is running. 217 * Depending on the memory size, the watchdog might trigger, while we 218 * are still saving the memory. 219 * We reuse the open flag to ensure that suspend and watchdog open are 220 * exclusive operations 221 */ 222 static int wdt_suspend(void) 223 { 224 if (test_and_set_bit(WDOG_DEV_OPEN, &wdt_dev.status)) { 225 pr_err("Linux cannot be suspended while the watchdog is in use\n"); 226 return notifier_from_errno(-EBUSY); 227 } 228 if (test_bit(WDOG_ACTIVE, &wdt_dev.status)) { 229 clear_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 return NOTIFY_DONE; 234 } 235 236 static int wdt_resume(void) 237 { 238 clear_bit(WDOG_DEV_OPEN, &wdt_dev.status); 239 return NOTIFY_DONE; 240 } 241 242 static int wdt_power_event(struct notifier_block *this, unsigned long event, 243 void *ptr) 244 { 245 switch (event) { 246 case PM_POST_HIBERNATION: 247 case PM_POST_SUSPEND: 248 return wdt_resume(); 249 case PM_HIBERNATION_PREPARE: 250 case PM_SUSPEND_PREPARE: 251 return wdt_suspend(); 252 default: 253 return NOTIFY_DONE; 254 } 255 } 256 257 static struct notifier_block wdt_power_notifier = { 258 .notifier_call = wdt_power_event, 259 }; 260 261 static int __init diag288_init(void) 262 { 263 int ret; 264 char ebc_begin[] = { 265 194, 197, 199, 201, 213 266 }; 267 268 watchdog_set_nowayout(&wdt_dev, nowayout_info); 269 270 if (MACHINE_IS_VM) { 271 if (__diag288_vm(WDT_FUNC_INIT, 15, 272 ebc_begin, sizeof(ebc_begin)) != 0) { 273 pr_err("The watchdog cannot be initialized\n"); 274 return -EINVAL; 275 } 276 } else { 277 if (__diag288_lpar(WDT_FUNC_INIT, 30, LPARWDT_RESTART)) { 278 pr_err("The watchdog cannot be initialized\n"); 279 return -EINVAL; 280 } 281 } 282 283 if (__diag288_lpar(WDT_FUNC_CANCEL, 0, 0)) { 284 pr_err("The watchdog cannot be deactivated\n"); 285 return -EINVAL; 286 } 287 288 ret = register_pm_notifier(&wdt_power_notifier); 289 if (ret) 290 return ret; 291 292 ret = watchdog_register_device(&wdt_dev); 293 if (ret) 294 unregister_pm_notifier(&wdt_power_notifier); 295 296 return ret; 297 } 298 299 static void __exit diag288_exit(void) 300 { 301 watchdog_unregister_device(&wdt_dev); 302 unregister_pm_notifier(&wdt_power_notifier); 303 } 304 305 module_init(diag288_init); 306 module_exit(diag288_exit); 307