// SPDX-License-Identifier: GPL-2.0-only
/*
* Watchdog driver for z/VM and LPAR using the diag 288 interface.
*
* Under z/VM, expiration of the watchdog will send a "system restart" command
* to CP.
*
* The command can be altered using the module parameter "cmd". This is
* not recommended because it's only supported on z/VM but not whith LPAR.
*
* On LPAR, the watchdog will always trigger a system restart. the module
* paramter cmd is meaningless here.
*
*
* Copyright IBM Corp. 2004, 2013
* Author(s): Arnd Bergmann ([email protected])
* Philipp Hachtmann ([email protected])
*
*/
#define KMSG_COMPONENT "diag288_wdt"
#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/slab.h>
#include <linux/watchdog.h>
#include <asm/ebcdic.h>
#include <asm/diag.h>
#include <linux/io.h>
#define MAX_CMDLEN 240
#define DEFAULT_CMD "SYSTEM RESTART"
#define MIN_INTERVAL 15 /* Minimal time supported by diag88 */
#define MAX_INTERVAL 3600 /* One hour should be enough - pure estimation */
#define WDT_DEFAULT_TIMEOUT 30
/* Function codes - init, change, cancel */
#define WDT_FUNC_INIT 0
#define WDT_FUNC_CHANGE 1
#define WDT_FUNC_CANCEL 2
#define WDT_FUNC_CONCEAL 0x80000000
/* Action codes for LPAR watchdog */
#define LPARWDT_RESTART 0
static char wdt_cmd[MAX_CMDLEN] = DEFAULT_CMD;
static bool conceal_on;
static bool nowayout_info = WATCHDOG_NOWAYOUT;
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Arnd Bergmann <[email protected]>");
MODULE_AUTHOR("Philipp Hachtmann <[email protected]>");
MODULE_DESCRIPTION("System z diag288 Watchdog Timer");
module_param_string(cmd, wdt_cmd, MAX_CMDLEN, 0644);
MODULE_PARM_DESC(cmd, "CP command that is run when the watchdog triggers (z/VM only)");
module_param_named(conceal, conceal_on, bool, 0644);
MODULE_PARM_DESC(conceal, "Enable the CONCEAL CP option while the watchdog is active (z/VM only)");
module_param_named(nowayout, nowayout_info, bool, 0444);
MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default = CONFIG_WATCHDOG_NOWAYOUT)");
MODULE_ALIAS("vmwatchdog");
static char *cmd_buf;
static int diag288(unsigned int func, unsigned int timeout,
unsigned long action, unsigned int len)
{
union register_pair r1 = { .even = func, .odd = timeout, };
union register_pair r3 = { .even = action, .odd = len, };
int err;
diag_stat_inc(DIAG_STAT_X288);
err = -EINVAL;
asm volatile(
" diag %[r1],%[r3],0x288\n"
"0: la %[err],0\n"
"1:\n"
EX_TABLE(0b, 1b)
: [err] "+d" (err)
: [r1] "d" (r1.pair), [r3] "d" (r3.pair)
: "cc", "memory");
return err;
}
static int diag288_str(unsigned int func, unsigned int timeout, char *cmd)
{
ssize_t len;
len = strscpy(cmd_buf, cmd, MAX_CMDLEN);
if (len < 0)
return len;
ASCEBC(cmd_buf, MAX_CMDLEN);
EBC_TOUPPER(cmd_buf, MAX_CMDLEN);
return diag288(func, timeout, virt_to_phys(cmd_buf), len);
}
static int wdt_start(struct watchdog_device *dev)
{
int ret;
unsigned int func;
if (MACHINE_IS_VM) {
func = conceal_on ? (WDT_FUNC_INIT | WDT_FUNC_CONCEAL)
: WDT_FUNC_INIT;
ret = diag288_str(func, dev->timeout, wdt_cmd);
WARN_ON(ret != 0);
} else {
ret = diag288(WDT_FUNC_INIT, dev->timeout, LPARWDT_RESTART, 0);
}
if (ret) {
pr_err("The watchdog cannot be activated\n");
return ret;
}
return 0;
}
static int wdt_stop(struct watchdog_device *dev)
{
return diag288(WDT_FUNC_CANCEL, 0, 0, 0);
}
static int wdt_ping(struct watchdog_device *dev)
{
int ret;
unsigned int func;
if (MACHINE_IS_VM) {
/*
* It seems to be ok to z/VM to use the init function to
* retrigger the watchdog. On LPAR WDT_FUNC_CHANGE must
* be used when the watchdog is running.
*/
func = conceal_on ? (WDT_FUNC_INIT | WDT_FUNC_CONCEAL)
: WDT_FUNC_INIT;
ret = diag288_str(func, dev->timeout, wdt_cmd);
WARN_ON(ret != 0);
} else {
ret = diag288(WDT_FUNC_CHANGE, dev->timeout, 0, 0);
}
if (ret)
pr_err("The watchdog timer cannot be started or reset\n");
return ret;
}
static int wdt_set_timeout(struct watchdog_device * dev, unsigned int new_to)
{
dev->timeout = new_to;
return wdt_ping(dev);
}
static const struct watchdog_ops wdt_ops = {
.owner = THIS_MODULE,
.start = wdt_start,
.stop = wdt_stop,
.ping = wdt_ping,
.set_timeout = wdt_set_timeout,
};
static const struct watchdog_info wdt_info = {
.options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
.firmware_version = 0,
.identity = "z Watchdog",
};
static struct watchdog_device wdt_dev = {
.parent = NULL,
.info = &wdt_info,
.ops = &wdt_ops,
.bootstatus = 0,
.timeout = WDT_DEFAULT_TIMEOUT,
.min_timeout = MIN_INTERVAL,
.max_timeout = MAX_INTERVAL,
};
static int __init diag288_init(void)
{
int ret;
watchdog_set_nowayout(&wdt_dev, nowayout_info);
if (MACHINE_IS_VM) {
cmd_buf = kmalloc(MAX_CMDLEN, GFP_KERNEL);
if (!cmd_buf) {
pr_err("The watchdog cannot be initialized\n");
return -ENOMEM;
}
ret = diag288_str(WDT_FUNC_INIT, MIN_INTERVAL, "BEGIN");
if (ret != 0) {
pr_err("The watchdog cannot be initialized\n");
kfree(cmd_buf);
return -EINVAL;
}
} else {
if (diag288(WDT_FUNC_INIT, WDT_DEFAULT_TIMEOUT,
LPARWDT_RESTART, 0)) {
pr_err("The watchdog cannot be initialized\n");
return -EINVAL;
}
}
if (diag288(WDT_FUNC_CANCEL, 0, 0, 0)) {
pr_err("The watchdog cannot be deactivated\n");
return -EINVAL;
}
return watchdog_register_device(&wdt_dev);
}
static void __exit diag288_exit(void)
{
watchdog_unregister_device(&wdt_dev);
kfree(cmd_buf);
}
module_init(diag288_init);
module_exit(diag288_exit);
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