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 <asm/ebcdic.h> 31 #include <asm/diag.h> 32 #include <linux/io.h> 33 34 #define MAX_CMDLEN 240 35 #define DEFAULT_CMD "SYSTEM RESTART" 36 37 #define MIN_INTERVAL 15 /* Minimal time supported by diag88 */ 38 #define MAX_INTERVAL 3600 /* One hour should be enough - pure estimation */ 39 40 #define WDT_DEFAULT_TIMEOUT 30 41 42 /* Function codes - init, change, cancel */ 43 #define WDT_FUNC_INIT 0 44 #define WDT_FUNC_CHANGE 1 45 #define WDT_FUNC_CANCEL 2 46 #define WDT_FUNC_CONCEAL 0x80000000 47 48 /* Action codes for LPAR watchdog */ 49 #define LPARWDT_RESTART 0 50 51 static char wdt_cmd[MAX_CMDLEN] = DEFAULT_CMD; 52 static bool conceal_on; 53 static bool nowayout_info = WATCHDOG_NOWAYOUT; 54 55 MODULE_LICENSE("GPL"); 56 MODULE_AUTHOR("Arnd Bergmann <arndb@de.ibm.com>"); 57 MODULE_AUTHOR("Philipp Hachtmann <phacht@de.ibm.com>"); 58 59 MODULE_DESCRIPTION("System z diag288 Watchdog Timer"); 60 61 module_param_string(cmd, wdt_cmd, MAX_CMDLEN, 0644); 62 MODULE_PARM_DESC(cmd, "CP command that is run when the watchdog triggers (z/VM only)"); 63 64 module_param_named(conceal, conceal_on, bool, 0644); 65 MODULE_PARM_DESC(conceal, "Enable the CONCEAL CP option while the watchdog is active (z/VM only)"); 66 67 module_param_named(nowayout, nowayout_info, bool, 0444); 68 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default = CONFIG_WATCHDOG_NOWAYOUT)"); 69 70 MODULE_ALIAS("vmwatchdog"); 71 72 static char *cmd_buf; 73 74 static int diag288(unsigned int func, unsigned int timeout, 75 unsigned long action, unsigned int len) 76 { 77 union register_pair r1 = { .even = func, .odd = timeout, }; 78 union register_pair r3 = { .even = action, .odd = len, }; 79 int err; 80 81 diag_stat_inc(DIAG_STAT_X288); 82 83 err = -EINVAL; 84 asm volatile( 85 " diag %[r1],%[r3],0x288\n" 86 "0: la %[err],0\n" 87 "1:\n" 88 EX_TABLE(0b, 1b) 89 : [err] "+d" (err) 90 : [r1] "d" (r1.pair), [r3] "d" (r3.pair) 91 : "cc", "memory"); 92 return err; 93 } 94 95 static int diag288_str(unsigned int func, unsigned int timeout, char *cmd) 96 { 97 ssize_t len; 98 99 len = strscpy(cmd_buf, cmd, MAX_CMDLEN); 100 if (len < 0) 101 return len; 102 ASCEBC(cmd_buf, MAX_CMDLEN); 103 EBC_TOUPPER(cmd_buf, MAX_CMDLEN); 104 105 return diag288(func, timeout, virt_to_phys(cmd_buf), len); 106 } 107 108 static int wdt_start(struct watchdog_device *dev) 109 { 110 int ret; 111 unsigned int func; 112 113 if (MACHINE_IS_VM) { 114 func = conceal_on ? (WDT_FUNC_INIT | WDT_FUNC_CONCEAL) 115 : WDT_FUNC_INIT; 116 ret = diag288_str(func, dev->timeout, wdt_cmd); 117 WARN_ON(ret != 0); 118 } else { 119 ret = diag288(WDT_FUNC_INIT, dev->timeout, LPARWDT_RESTART, 0); 120 } 121 122 if (ret) { 123 pr_err("The watchdog cannot be activated\n"); 124 return ret; 125 } 126 return 0; 127 } 128 129 static int wdt_stop(struct watchdog_device *dev) 130 { 131 return diag288(WDT_FUNC_CANCEL, 0, 0, 0); 132 } 133 134 static int wdt_ping(struct watchdog_device *dev) 135 { 136 int ret; 137 unsigned int func; 138 139 if (MACHINE_IS_VM) { 140 /* 141 * It seems to be ok to z/VM to use the init function to 142 * retrigger the watchdog. On LPAR WDT_FUNC_CHANGE must 143 * be used when the watchdog is running. 144 */ 145 func = conceal_on ? (WDT_FUNC_INIT | WDT_FUNC_CONCEAL) 146 : WDT_FUNC_INIT; 147 148 ret = diag288_str(func, dev->timeout, wdt_cmd); 149 WARN_ON(ret != 0); 150 } else { 151 ret = diag288(WDT_FUNC_CHANGE, dev->timeout, 0, 0); 152 } 153 154 if (ret) 155 pr_err("The watchdog timer cannot be started or reset\n"); 156 return ret; 157 } 158 159 static int wdt_set_timeout(struct watchdog_device * dev, unsigned int new_to) 160 { 161 dev->timeout = new_to; 162 return wdt_ping(dev); 163 } 164 165 static const struct watchdog_ops wdt_ops = { 166 .owner = THIS_MODULE, 167 .start = wdt_start, 168 .stop = wdt_stop, 169 .ping = wdt_ping, 170 .set_timeout = wdt_set_timeout, 171 }; 172 173 static const struct watchdog_info wdt_info = { 174 .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE, 175 .firmware_version = 0, 176 .identity = "z Watchdog", 177 }; 178 179 static struct watchdog_device wdt_dev = { 180 .parent = NULL, 181 .info = &wdt_info, 182 .ops = &wdt_ops, 183 .bootstatus = 0, 184 .timeout = WDT_DEFAULT_TIMEOUT, 185 .min_timeout = MIN_INTERVAL, 186 .max_timeout = MAX_INTERVAL, 187 }; 188 189 static int __init diag288_init(void) 190 { 191 int ret; 192 193 watchdog_set_nowayout(&wdt_dev, nowayout_info); 194 195 if (MACHINE_IS_VM) { 196 cmd_buf = kmalloc(MAX_CMDLEN, GFP_KERNEL); 197 if (!cmd_buf) { 198 pr_err("The watchdog cannot be initialized\n"); 199 return -ENOMEM; 200 } 201 202 ret = diag288_str(WDT_FUNC_INIT, MIN_INTERVAL, "BEGIN"); 203 if (ret != 0) { 204 pr_err("The watchdog cannot be initialized\n"); 205 kfree(cmd_buf); 206 return -EINVAL; 207 } 208 } else { 209 if (diag288(WDT_FUNC_INIT, WDT_DEFAULT_TIMEOUT, 210 LPARWDT_RESTART, 0)) { 211 pr_err("The watchdog cannot be initialized\n"); 212 return -EINVAL; 213 } 214 } 215 216 if (diag288(WDT_FUNC_CANCEL, 0, 0, 0)) { 217 pr_err("The watchdog cannot be deactivated\n"); 218 return -EINVAL; 219 } 220 221 return watchdog_register_device(&wdt_dev); 222 } 223 224 static void __exit diag288_exit(void) 225 { 226 watchdog_unregister_device(&wdt_dev); 227 kfree(cmd_buf); 228 } 229 230 module_init(diag288_init); 231 module_exit(diag288_exit); 232