1 files changed, 231 insertions, 0 deletions
diff --git a/drivers/watchdog/diag288_wdt.c b/drivers/watchdog/diag288_wdt.c
new file mode 100644
index 0000000000..4631d0a386
--- /dev/null
+++ b/drivers/watchdog/diag288_wdt.c
@@ -0,0 +1,231 @@
+// 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 (arndb@de.ibm.com)
+ *	      Philipp Hachtmann (phacht@de.ibm.com)
+ *
+ */
+
+#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 <arndb@de.ibm.com>");
+MODULE_AUTHOR("Philipp Hachtmann <phacht@de.ibm.com>");
+
+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);