1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * Watchdog driver for z/VM and LPAR using the diag 288 interface. 4 * 5 * Under z/VM, expiration of the watchdog will send a "system restart" command 6 * to CP. 7 * 8 * The command can be altered using the module parameter "cmd". This is 9 * not recommended because it's only supported on z/VM but not whith LPAR. 10 * 11 * On LPAR, the watchdog will always trigger a system restart. the module 12 * paramter cmd is meaningless here. 13 * 14 * 15 * Copyright IBM Corp. 2004, 2013 16 * Author(s): Arnd Bergmann (arndb@de.ibm.com) 17 * Philipp Hachtmann (phacht@de.ibm.com) 18 * 19 */ 20 21 #define KMSG_COMPONENT "diag288_wdt" 22 #define pr_fmt(fmt) KMSG_COMPONENT ": " fmt 23 24 #include <linux/init.h> 25 #include <linux/kernel.h> 26 #include <linux/module.h> 27 #include <linux/moduleparam.h> 28 #include <linux/slab.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 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("vmwatchdog"); 72 73 static int __diag288(unsigned int func, unsigned int timeout, 74 unsigned long action, unsigned int len) 75 { 76 register unsigned long __func asm("2") = func; 77 register unsigned long __timeout asm("3") = timeout; 78 register unsigned long __action asm("4") = action; 79 register unsigned long __len asm("5") = len; 80 int err; 81 82 err = -EINVAL; 83 asm volatile( 84 " diag %1, %3, 0x288\n" 85 "0: la %0, 0\n" 86 "1:\n" 87 EX_TABLE(0b, 1b) 88 : "+d" (err) : "d"(__func), "d"(__timeout), 89 "d"(__action), "d"(__len) : "1", "cc"); 90 return err; 91 } 92 93 static int __diag288_vm(unsigned int func, unsigned int timeout, 94 char *cmd, size_t len) 95 { 96 diag_stat_inc(DIAG_STAT_X288); 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 diag_stat_inc(DIAG_STAT_X288); 104 return __diag288(func, timeout, action, 0); 105 } 106 107 static unsigned long wdt_status; 108 109 #define DIAG_WDOG_BUSY 0 110 111 static int wdt_start(struct watchdog_device *dev) 112 { 113 char *ebc_cmd; 114 size_t len; 115 int ret; 116 unsigned int func; 117 118 if (test_and_set_bit(DIAG_WDOG_BUSY, &wdt_status)) 119 return -EBUSY; 120 121 if (MACHINE_IS_VM) { 122 ebc_cmd = kmalloc(MAX_CMDLEN, GFP_KERNEL); 123 if (!ebc_cmd) { 124 clear_bit(DIAG_WDOG_BUSY, &wdt_status); 125 return -ENOMEM; 126 } 127 len = strlcpy(ebc_cmd, wdt_cmd, MAX_CMDLEN); 128 ASCEBC(ebc_cmd, MAX_CMDLEN); 129 EBC_TOUPPER(ebc_cmd, MAX_CMDLEN); 130 131 func = conceal_on ? (WDT_FUNC_INIT | WDT_FUNC_CONCEAL) 132 : WDT_FUNC_INIT; 133 ret = __diag288_vm(func, dev->timeout, ebc_cmd, len); 134 WARN_ON(ret != 0); 135 kfree(ebc_cmd); 136 } else { 137 ret = __diag288_lpar(WDT_FUNC_INIT, 138 dev->timeout, LPARWDT_RESTART); 139 } 140 141 if (ret) { 142 pr_err("The watchdog cannot be activated\n"); 143 clear_bit(DIAG_WDOG_BUSY, &wdt_status); 144 return ret; 145 } 146 return 0; 147 } 148 149 static int wdt_stop(struct watchdog_device *dev) 150 { 151 int ret; 152 153 diag_stat_inc(DIAG_STAT_X288); 154 ret = __diag288(WDT_FUNC_CANCEL, 0, 0, 0); 155 156 clear_bit(DIAG_WDOG_BUSY, &wdt_status); 157 158 return ret; 159 } 160 161 static int wdt_ping(struct watchdog_device *dev) 162 { 163 char *ebc_cmd; 164 size_t len; 165 int ret; 166 unsigned int func; 167 168 if (MACHINE_IS_VM) { 169 ebc_cmd = kmalloc(MAX_CMDLEN, GFP_KERNEL); 170 if (!ebc_cmd) 171 return -ENOMEM; 172 len = strlcpy(ebc_cmd, wdt_cmd, MAX_CMDLEN); 173 ASCEBC(ebc_cmd, MAX_CMDLEN); 174 EBC_TOUPPER(ebc_cmd, MAX_CMDLEN); 175 176 /* 177 * It seems to be ok to z/VM to use the init function to 178 * retrigger the watchdog. On LPAR WDT_FUNC_CHANGE must 179 * be used when the watchdog is running. 180 */ 181 func = conceal_on ? (WDT_FUNC_INIT | WDT_FUNC_CONCEAL) 182 : WDT_FUNC_INIT; 183 184 ret = __diag288_vm(func, dev->timeout, ebc_cmd, len); 185 WARN_ON(ret != 0); 186 kfree(ebc_cmd); 187 } else { 188 ret = __diag288_lpar(WDT_FUNC_CHANGE, dev->timeout, 0); 189 } 190 191 if (ret) 192 pr_err("The watchdog timer cannot be started or reset\n"); 193 return ret; 194 } 195 196 static int wdt_set_timeout(struct watchdog_device * dev, unsigned int new_to) 197 { 198 dev->timeout = new_to; 199 return wdt_ping(dev); 200 } 201 202 static const struct watchdog_ops wdt_ops = { 203 .owner = THIS_MODULE, 204 .start = wdt_start, 205 .stop = wdt_stop, 206 .ping = wdt_ping, 207 .set_timeout = wdt_set_timeout, 208 }; 209 210 static const struct watchdog_info wdt_info = { 211 .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE, 212 .firmware_version = 0, 213 .identity = "z Watchdog", 214 }; 215 216 static struct watchdog_device wdt_dev = { 217 .parent = NULL, 218 .info = &wdt_info, 219 .ops = &wdt_ops, 220 .bootstatus = 0, 221 .timeout = WDT_DEFAULT_TIMEOUT, 222 .min_timeout = MIN_INTERVAL, 223 .max_timeout = MAX_INTERVAL, 224 }; 225 226 /* 227 * It makes no sense to go into suspend while the watchdog is running. 228 * Depending on the memory size, the watchdog might trigger, while we 229 * are still saving the memory. 230 */ 231 static int wdt_suspend(void) 232 { 233 if (test_and_set_bit(DIAG_WDOG_BUSY, &wdt_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(DIAG_WDOG_BUSY, &wdt_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); 311