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1// SPDX-License-Identifier: GPL-2.0-only2/*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" command6 * to CP.7 *8 * The command can be altered using the module parameter "cmd". This is9 * 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 module12 * paramter cmd is meaningless here.13 *14 *15 * Copyright IBM Corp. 2004, 201316 * 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 ": " fmt23 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 24035#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 3041 42/* Function codes - init, change, cancel */43#define WDT_FUNC_INIT 044#define WDT_FUNC_CHANGE 145#define WDT_FUNC_CANCEL 246#define WDT_FUNC_CONCEAL 0x8000000047 48/* Action codes for LPAR watchdog */49#define LPARWDT_RESTART 050 51static char wdt_cmd[MAX_CMDLEN] = DEFAULT_CMD;52static bool conceal_on;53static bool nowayout_info = WATCHDOG_NOWAYOUT;54 55MODULE_LICENSE("GPL");56MODULE_AUTHOR("Arnd Bergmann <arndb@de.ibm.com>");57MODULE_AUTHOR("Philipp Hachtmann <phacht@de.ibm.com>");58 59MODULE_DESCRIPTION("System z diag288 Watchdog Timer");60 61module_param_string(cmd, wdt_cmd, MAX_CMDLEN, 0644);62MODULE_PARM_DESC(cmd, "CP command that is run when the watchdog triggers (z/VM only)");63 64module_param_named(conceal, conceal_on, bool, 0644);65MODULE_PARM_DESC(conceal, "Enable the CONCEAL CP option while the watchdog is active (z/VM only)");66 67module_param_named(nowayout, nowayout_info, bool, 0444);68MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default = CONFIG_WATCHDOG_NOWAYOUT)");69 70MODULE_ALIAS("vmwatchdog");71 72static char *cmd_buf;73 74static 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 95static 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 108static 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 129static int wdt_stop(struct watchdog_device *dev)130{131 return diag288(WDT_FUNC_CANCEL, 0, 0, 0);132}133 134static 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 to142 * retrigger the watchdog. On LPAR WDT_FUNC_CHANGE must143 * 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 159static 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 165static 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 173static const struct watchdog_info wdt_info = {174 .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,175 .firmware_version = 0,176 .identity = "z Watchdog",177};178 179static 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 189static 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 224static void __exit diag288_exit(void)225{226 watchdog_unregister_device(&wdt_dev);227 kfree(cmd_buf);228}229 230module_init(diag288_init);231module_exit(diag288_exit);232