[PATCH] watchdog: add sun4v_wdt device support

* [PATCH] watchdog: add sun4v_wdt device support
@ 2016-01-12 23:10 ` wim.coekaerts
  0 siblings, 0 replies; 34+ messages in thread
From: wim.coekaerts @ 2016-01-12 23:10 UTC (permalink / raw)
  To: wim; +Cc: linux-watchdog, sparclinux

From: Wim Coekaerts <wim.coekaerts@oracle.com>

This adds a simple watchdog timer for the SPARC sunv4 architecture.
Export the sun4v_mach_set_watchdog() hv call, and add the target.
The driver was based on the same model used by the Xen watchdog driver.

This was tested on T2, T4, T5 and T7.

Signed-off-by: Wim Coekaerts <wim.coekaerts@oracle.com>
---
 arch/sparc/kernel/sparc_ksyms_64.c |    1 +
 drivers/watchdog/Kconfig           |   10 +
 drivers/watchdog/Makefile          |    1 +
 drivers/watchdog/sun4v_wdt.c       |  421 ++++++++++++++++++++++++++++++++++++
 4 files changed, 433 insertions(+), 0 deletions(-)
 create mode 100644 drivers/watchdog/sun4v_wdt.c

diff --git a/arch/sparc/kernel/sparc_ksyms_64.c b/arch/sparc/kernel/sparc_ksyms_64.c
index a92d5d2..9e034f2 100644
--- a/arch/sparc/kernel/sparc_ksyms_64.c
+++ b/arch/sparc/kernel/sparc_ksyms_64.c
@@ -37,6 +37,7 @@ EXPORT_SYMBOL(sun4v_niagara_getperf);
 EXPORT_SYMBOL(sun4v_niagara_setperf);
 EXPORT_SYMBOL(sun4v_niagara2_getperf);
 EXPORT_SYMBOL(sun4v_niagara2_setperf);
+EXPORT_SYMBOL(sun4v_mach_set_watchdog);
 
 /* from hweight.S */
 EXPORT_SYMBOL(__arch_hweight8);
diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
index 1c427be..08834e4 100644
--- a/drivers/watchdog/Kconfig
+++ b/drivers/watchdog/Kconfig
@@ -1516,6 +1516,16 @@ config UML_WATCHDOG
 	tristate "UML watchdog"
 	depends on UML
 
+# SPARC sun4v
+
+config WATCHDOG_SUN4V 
+	tristate "Sun4v Watchdog support"
+	depends on SPARC64
+	help
+	  Say Y here to support the hypervisor watchdog capability provided
+	  by the sun4v architecture.  The watchdog timeout period is normally one
+	  minute but can be changed with a boot-time parameter.
+
 #
 # ISA-based Watchdog Cards
 #
diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
index 53d4827..9b8acb8 100644
--- a/drivers/watchdog/Makefile
+++ b/drivers/watchdog/Makefile
@@ -175,6 +175,7 @@ obj-$(CONFIG_SH_WDT) += shwdt.o
 
 obj-$(CONFIG_WATCHDOG_RIO)		+= riowd.o
 obj-$(CONFIG_WATCHDOG_CP1XXX)		+= cpwd.o
+obj-$(CONFIG_WATCHDOG_SUN4V)		+= sun4v_wdt.o
 
 # XTENSA Architecture
 
diff --git a/drivers/watchdog/sun4v_wdt.c b/drivers/watchdog/sun4v_wdt.c
new file mode 100644
index 0000000..1213a1f
--- /dev/null
+++ b/drivers/watchdog/sun4v_wdt.c
@@ -0,0 +1,421 @@
+/*
+ *	Sun4v Watchdog Driver
+ *	(c) Copyright 2015 Oracle Corporation
+ *
+ *	Heavily modified version of xen_wdt.c 
+ *      (c) Copyright 2010 Novell, Inc.
+ *
+ *
+ *	This program is free software; you can redistribute it and/or
+ *	modify it under the terms of the GNU General Public License
+ *	as published by the Free Software Foundation; either version
+ *	2 of the License, or (at your option) any later version.
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#define DRV_NAME	"sun4v_wdt"
+#define DRV_VERSION	"0.01"
+
+#include <linux/bug.h>
+#include <linux/errno.h>
+#include <linux/fs.h>
+#include <linux/hrtimer.h>
+#include <linux/kernel.h>
+#include <linux/ktime.h>
+#include <linux/init.h>
+#include <linux/miscdevice.h>
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include <linux/platform_device.h>
+#include <linux/spinlock.h>
+#include <linux/uaccess.h>
+#include <linux/watchdog.h>
+#include <asm/hypervisor.h>
+#include <asm/mdesc.h>
+
+
+static struct platform_device *platform_device;
+static DEFINE_SPINLOCK(wdt_lock);
+static __kernel_time_t wdt_expires;
+static unsigned long is_active;
+static bool expect_release;
+
+unsigned long wdt_timeout = 0;
+
+#define WATCHDOG_TIMEOUT 60 /* in seconds */
+static unsigned long timeout = WATCHDOG_TIMEOUT;
+module_param(timeout, ulong, S_IRUGO);
+MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds "
+	"(default=" __MODULE_STRING(WATCHDOG_TIMEOUT) ")");
+
+static bool nowayout = WATCHDOG_NOWAYOUT;
+module_param(nowayout, bool, S_IRUGO);
+MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started "
+	"(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
+
+static inline __kernel_time_t set_timeout(void)
+{
+	/* 
+	 * The hypervisor specifies WD timeout in milliseconds 
+	 * Change it to seconds here and 
+	 * to do it in one place rather than every call to
+	 * sun4v_mach_set_watchdog()
+	 * The hvcall expects milliseconds while the parameters
+	 * and the rest of the code expects seconds. wdt_timeout
+	 * is the variable that we pass to the hvcall.
+	 */
+	wdt_timeout = timeout * 1000; 
+	return ktime_to_timespec(ktime_get()).tv_sec + timeout;
+}
+
+static int sun4v_wdt_start(void)
+{
+	__kernel_time_t expires;
+	unsigned long time_remaining;
+	int err;
+
+	spin_lock(&wdt_lock);
+
+	expires = set_timeout();
+	err = sun4v_mach_set_watchdog(wdt_timeout, &time_remaining);
+
+	spin_unlock(&wdt_lock);
+
+	pr_info("Watchdog timer enabled\n");
+	return err;
+}
+
+static int sun4v_wdt_stop(void)
+{
+	int err;
+	unsigned long time_remaining;
+
+	spin_lock(&wdt_lock);
+
+        err = sun4v_mach_set_watchdog(0, &time_remaining);
+
+	spin_unlock(&wdt_lock);
+
+	pr_info("Watchdog timer disabled\n");
+	return err;
+}
+
+static int sun4v_wdt_kick(void)
+{
+	__kernel_time_t expires;
+	int err;
+	unsigned long time_remaining;
+
+	spin_lock(&wdt_lock);
+
+	expires = set_timeout();
+        err = sun4v_mach_set_watchdog(wdt_timeout, &time_remaining);
+	if (!err)
+		wdt_expires = expires;
+
+	spin_unlock(&wdt_lock);
+
+	return err;
+}
+
+static int sun4v_wdt_open(struct inode *inode, struct file *file)
+{
+	int err;
+
+	/* /dev/watchdog can only be opened once */
+	if (test_and_set_bit(0, &is_active)) 
+		return -EBUSY;
+
+	/* prevent someone from rmmod'ing the module */
+	if (nowayout)
+		__module_get(THIS_MODULE);
+
+	err = sun4v_wdt_start();
+	if (err == -EBUSY) {
+		err = sun4v_wdt_kick();
+	}
+
+	return err ?: nonseekable_open(inode, file);
+}
+
+static int sun4v_wdt_release(struct inode *inode, struct file *file)
+{
+	int err;
+
+	if (expect_release)
+		err = sun4v_wdt_stop();
+	else {
+		pr_crit("Unexpected close, not stopping watchdog!\n");
+		sun4v_wdt_kick();
+	}
+
+	clear_bit(0, &is_active);
+	expect_release = false;
+
+	return 0;
+}
+
+static ssize_t sun4v_wdt_write(struct file *file, const char __user *data,
+			     size_t len, loff_t *ppos)
+{
+	/* See if we got the magic character 'V' and reload the timer */
+	if (len) {
+		if (!nowayout) {
+			size_t i;
+
+			/* in case it was set long ago */
+			expect_release = false;
+
+			/* scan to see whether or not we got the magic
+			   character */
+			for (i = 0; i != len; i++) {
+				char c;
+				if (get_user(c, data + i))
+					return -EFAULT;
+				if (c == 'V') 
+					expect_release = true;
+			}
+		}
+
+		/* someone wrote to us, we should reload the timer */
+		sun4v_wdt_kick();
+	}
+	return len;
+}
+
+static long sun4v_wdt_ioctl(struct file *file, unsigned int cmd,
+			  unsigned long arg)
+{
+	int new_options, retval = -EINVAL;
+	int new_timeout;
+	int __user *argp = (void __user *)arg;
+	static const struct watchdog_info ident = {
+		.options =		WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE,
+		.firmware_version =	0,
+		.identity =		"SUN4V Watchdog",
+	};
+
+	switch (cmd) {
+	case WDIOC_GETSUPPORT:
+		return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
+
+	case WDIOC_GETSTATUS:
+	case WDIOC_GETBOOTSTATUS:
+		return put_user(0, argp);
+
+	case WDIOC_SETOPTIONS:
+		if (get_user(new_options, argp))
+			return -EFAULT;
+
+		if (new_options & WDIOS_DISABLECARD)
+			retval = sun4v_wdt_stop();
+		if (new_options & WDIOS_ENABLECARD) {
+			retval = sun4v_wdt_start();
+			if (retval == -EBUSY)
+				retval = sun4v_wdt_kick();
+		}
+		return retval;
+
+	case WDIOC_KEEPALIVE:
+		sun4v_wdt_kick();
+		return 0;
+
+	case WDIOC_SETTIMEOUT:
+		if (get_user(new_timeout, argp))
+			return -EFAULT;
+		if (!new_timeout)
+			return -EINVAL;
+		timeout = new_timeout;
+		sun4v_wdt_kick();
+		/* fall through */
+	case WDIOC_GETTIMEOUT:
+		return put_user(timeout, argp);
+
+	case WDIOC_GETTIMELEFT:
+		retval = wdt_expires - ktime_to_timespec(ktime_get()).tv_sec;
+		return put_user(retval, argp);
+	}
+
+	return -ENOTTY;
+}
+
+static const struct file_operations sun4v_wdt_fops = {
+	.owner =		THIS_MODULE,
+	.llseek =		no_llseek,
+	.write =		sun4v_wdt_write,
+	.unlocked_ioctl =	sun4v_wdt_ioctl,
+	.open =			sun4v_wdt_open,
+	.release =		sun4v_wdt_release,
+};
+
+static struct miscdevice sun4v_wdt_miscdev = {
+	.minor =	WATCHDOG_MINOR,
+	.name =		"watchdog",
+	.fops =		&sun4v_wdt_fops,
+};
+
+static int sun4v_wdt_probe(struct platform_device *dev)
+{
+	unsigned long wd_timeout = 0;
+	unsigned long time_remaining;
+	int ret;
+
+	ret = sun4v_mach_set_watchdog(wd_timeout, &time_remaining);
+
+	switch (ret) {
+	case HV_EOK:
+		if (!timeout) {
+			timeout = WATCHDOG_TIMEOUT;
+			pr_info("timeout value invalid, using %lu\n", timeout);
+		}
+
+		ret = misc_register(&sun4v_wdt_miscdev);
+		if (ret) {
+			pr_err("cannot register miscdev on minor=%d (%d)\n",
+			       WATCHDOG_MINOR, ret);
+			break;
+		}
+
+		pr_info("initialized (timeout=%lus, nowayout=%d)\n",
+			timeout, nowayout);
+		break;
+
+	case -ENOSYS:
+		pr_info("not supported\n");
+		ret = -ENODEV;
+		break;
+
+	default:
+		pr_info("bogus return value %d\n", ret);
+		break;
+	}
+
+	return ret;
+}
+
+static int sun4v_wdt_remove(struct platform_device *dev)
+{
+	/* Stop the timer before we leave */
+
+	if (!nowayout)
+		sun4v_wdt_stop();
+
+	misc_deregister(&sun4v_wdt_miscdev);
+
+	return 0;
+}
+
+static void sun4v_wdt_shutdown(struct platform_device *dev)
+{
+	sun4v_wdt_stop();
+}
+
+static int sun4v_wdt_suspend(struct platform_device *dev, pm_message_t state)
+{
+	int ret = sun4v_wdt_stop();
+	return ret;
+}
+
+static int sun4v_wdt_resume(struct platform_device *dev)
+{
+	return sun4v_wdt_start();
+}
+
+static struct platform_driver sun4v_wdt_driver = {
+	.probe          = sun4v_wdt_probe,
+	.remove         = sun4v_wdt_remove,
+	.shutdown       = sun4v_wdt_shutdown,
+	.suspend        = sun4v_wdt_suspend,
+	.resume         = sun4v_wdt_resume,
+	.driver         = {
+		.name   = DRV_NAME,
+	},
+};
+
+static int __init sun4v_wdt_init_module(void)
+{
+	int err;
+	struct mdesc_handle *hp;
+	u64 pn;
+	const u64 *v;
+	u64 max_timeout = 0;
+	u64 resolution;
+
+	/*
+	 * There are 2 properties that can be set from the control
+	 * domain for the watchdog. 
+	 * watchdog-resolution (in ms defaulting to 1000) 
+	 * watchdog-max-timeout (in ms)
+	 * Right now, only support the default 1s (1000ms) resolution
+	 * so just verify against the property, and make sure
+	 * max timeout is taken into account, if set.
+	 */
+	hp = mdesc_grab();
+	pn = mdesc_node_by_name(hp, MDESC_NODE_NULL, "platform");
+
+	if (pn == MDESC_NODE_NULL) {
+		pr_info("No platform node \n");
+		return -ENODEV;
+	}
+
+	v = mdesc_get_property(hp, pn, "watchdog-resolution", NULL);
+	if (v) {
+		resolution = *v;
+		pr_info("Platform watchdog-resolution [%llux]\n", *v);
+		/* default resolution is 1000ms, should be fine */
+		/* not supporting anything else right now */
+		if (resolution != 1000) {
+			pr_crit("Only 1000ms is supported.\n");
+			return -EINVAL;	
+		}
+	}
+
+	v = mdesc_get_property(hp, pn, "watchdog-max-timeout", NULL);
+	if (v) {
+		max_timeout = *v;
+		pr_info("Platform watchdog-max-timeout [%llu ms]\n", *v);
+		if (max_timeout < 1000) {
+			pr_crit("Timeout should be at least 1s(1000ms)\n");
+			return -EINVAL;
+		}
+	}
+
+	/* have to convert timeout in seconds to timeout in milliseconds */
+	if (timeout * 1000 > max_timeout) { 
+		/* and convert down to seconds again */
+		timeout = max_timeout / 1000;
+		pr_info("Timeout larger than watchdog-max-timeout\n");
+		pr_info("Setting timeout to watchdog-max-timeout [%llu ms]\n", max_timeout);
+	}
+
+	pr_info("Sun4v WatchDog Timer Driver v%s\n", DRV_VERSION);
+
+	err = platform_driver_register(&sun4v_wdt_driver);
+	if (err)
+		return err;
+
+	platform_device = platform_device_register_simple(DRV_NAME,
+								  -1, NULL, 0);
+	if (IS_ERR(platform_device)) {
+		err = PTR_ERR(platform_device);
+		platform_driver_unregister(&sun4v_wdt_driver);
+	}
+
+	return err;
+}
+
+static void __exit sun4v_wdt_cleanup_module(void)
+{
+	platform_device_unregister(platform_device);
+	platform_driver_unregister(&sun4v_wdt_driver);
+	pr_info("module unloaded\n");
+}
+
+module_init(sun4v_wdt_init_module);
+module_exit(sun4v_wdt_cleanup_module);
+
+MODULE_AUTHOR("Wim Coekaerts <wim.coekaerts@oracle.com>");
+MODULE_DESCRIPTION("Sun4v WatchDog Timer Driver");
+MODULE_VERSION(DRV_VERSION);
+MODULE_LICENSE("GPL");
-- 
1.7.1


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