Add sun4v_wdt watchdog driver

This driver adds sparc hypervisor watchdog support. The default
timeout is 60 seconds and the range is between 1 and
31536000 seconds. Both watchdog-resolution and
watchdog-max-timeout MD properties settings are supported.

Signed-off-by: Wim Coekaerts <wim.coekaerts@oracle.com>
Reviewed-by: Julian Calaby <julian.calaby@gmail.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

6 files changed, 210 insertions, 1 deletions

diff --git a/Documentation/watchdog/watchdog-parameters.txt b/Documentation/watchdog/watchdog-parameters.txt
index 9f9ec9f76039..4e4b6f10d841 100644
--- a/Documentation/watchdog/watchdog-parameters.txt
+++ b/Documentation/watchdog/watchdog-parameters.txt
@@ -400,3 +400,7 @@ wm8350_wdt:
 nowayout: Watchdog cannot be stopped once started
         (default=kernel config parameter)
 -------------------------------------------------
+sun4v_wdt:
+timeout_ms: Watchdog timeout in milliseconds 1..180000, default=60000)
+nowayout: Watchdog cannot be stopped once started
+-------------------------------------------------
diff --git a/arch/sparc/kernel/hvcalls.S b/arch/sparc/kernel/hvcalls.S
index afbaba52d2f1..d127130bf424 100644
--- a/arch/sparc/kernel/hvcalls.S
+++ b/arch/sparc/kernel/hvcalls.S
@@ -338,8 +338,9 @@ ENTRY(sun4v_mach_set_watchdog)
         mov     %o1, %o4
         mov     HV_FAST_MACH_SET_WATCHDOG, %o5
         ta      HV_FAST_TRAP
+        brnz,a,pn %o4, 0f
         stx     %o1, [%o4]
-        retl
+0:      retl
          nop
 ENDPROC(sun4v_mach_set_watchdog)
 
diff --git a/arch/sparc/kernel/sparc_ksyms_64.c b/arch/sparc/kernel/sparc_ksyms_64.c
index a92d5d2c46a3..9e034f29dcc5 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 4f0e7be0da34..30d38ae685f6 100644
--- a/drivers/watchdog/Kconfig
+++ b/drivers/watchdog/Kconfig
@@ -1565,6 +1565,17 @@ config WATCHDOG_RIO
           machines.  The watchdog timeout period is normally one minute but
           can be changed with a boot-time parameter.
 
+config WATCHDOG_SUN4V
+        tristate "Sun4v Watchdog support"
+        select WATCHDOG_CORE
+        depends on SPARC64
+        help
+          Say Y here to support the hypervisor watchdog capability embedded
+          in the SPARC sun4v architecture.
+
+          To compile this driver as a module, choose M here. The module will
+          be called sun4v_wdt.
+
 # XTENSA Architecture
 
 # Xen Architecture
diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
index f566753256ab..f6a6a387c6c7 100644
--- a/drivers/watchdog/Makefile
+++ b/drivers/watchdog/Makefile
@@ -179,6 +179,7 @@ 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 000000000000..1467fe50a76f
--- /dev/null
+++ b/drivers/watchdog/sun4v_wdt.c
@@ -0,0 +1,191 @@
+/*
+ *      sun4v watchdog timer
+ *      (c) Copyright 2016 Oracle Corporation
+ *
+ *      Implement a simple watchdog driver using the built-in sun4v hypervisor
+ *      watchdog support. If time expires, the hypervisor stops or bounces
+ *      the guest domain.
+ *
+ *      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
+
+#include <linux/errno.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include <linux/watchdog.h>
+#include <asm/hypervisor.h>
+#include <asm/mdesc.h>
+
+#define WDT_TIMEOUT                     60
+#define WDT_MAX_TIMEOUT                 31536000
+#define WDT_MIN_TIMEOUT                 1
+#define WDT_DEFAULT_RESOLUTION_MS       1000    /* 1 second */
+
+static unsigned int timeout;
+module_param(timeout, uint, 0);
+MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds (default="
+        __MODULE_STRING(WDT_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 int sun4v_wdt_stop(struct watchdog_device *wdd)
+{
+        sun4v_mach_set_watchdog(0, NULL);
+
+        return 0;
+}
+
+static int sun4v_wdt_ping(struct watchdog_device *wdd)
+{
+        int hverr;
+
+        /*
+         * HV watchdog timer will round up the timeout
+         * passed in to the nearest multiple of the
+         * watchdog resolution in milliseconds.
+         */
+        hverr = sun4v_mach_set_watchdog(wdd->timeout * 1000, NULL);
+        if (hverr == HV_EINVAL)
+                return -EINVAL;
+
+        return 0;
+}
+
+static int sun4v_wdt_set_timeout(struct watchdog_device *wdd,
+                                 unsigned int timeout)
+{
+        wdd->timeout = timeout;
+
+        return 0;
+}
+
+static const struct watchdog_info sun4v_wdt_ident = {
+        .options =      WDIOF_SETTIMEOUT |
+                        WDIOF_MAGICCLOSE |
+                        WDIOF_KEEPALIVEPING,
+        .identity =     "sun4v hypervisor watchdog",
+        .firmware_version = 0,
+};
+
+static struct watchdog_ops sun4v_wdt_ops = {
+        .owner =        THIS_MODULE,
+        .start =        sun4v_wdt_ping,
+        .stop =         sun4v_wdt_stop,
+        .ping =         sun4v_wdt_ping,
+        .set_timeout =  sun4v_wdt_set_timeout,
+};
+
+static struct watchdog_device wdd = {
+        .info = &sun4v_wdt_ident,
+        .ops = &sun4v_wdt_ops,
+        .min_timeout = WDT_MIN_TIMEOUT,
+        .max_timeout = WDT_MAX_TIMEOUT,
+        .timeout = WDT_TIMEOUT,
+};
+
+static int __init sun4v_wdt_init(void)
+{
+        struct mdesc_handle *handle;
+        u64 node;
+        const u64 *value;
+        int err = 0;
+        unsigned long major = 1, minor = 1;
+
+        /*
+         * There are 2 properties that can be set from the control
+         * domain for the watchdog.
+         * watchdog-resolution
+         * watchdog-max-timeout
+         *
+         * We can expect a handle to be returned otherwise something
+         * serious is wrong. Correct to return -ENODEV here.
+         */
+
+        handle = mdesc_grab();
+        if (!handle)
+                return -ENODEV;
+
+        node = mdesc_node_by_name(handle, MDESC_NODE_NULL, "platform");
+        err = -ENODEV;
+        if (node == MDESC_NODE_NULL)
+                goto out_release;
+
+        /*
+         * This is a safe way to validate if we are on the right
+         * platform.
+         */
+        if (sun4v_hvapi_register(HV_GRP_CORE, major, &minor))
+                goto out_hv_unreg;
+
+        /* Allow value of watchdog-resolution up to 1s (default) */
+        value = mdesc_get_property(handle, node, "watchdog-resolution", NULL);
+        err = -EINVAL;
+        if (value) {
+                if (*value == 0 ||
+                    *value > WDT_DEFAULT_RESOLUTION_MS)
+                        goto out_hv_unreg;
+        }
+
+        value = mdesc_get_property(handle, node, "watchdog-max-timeout", NULL);
+        if (value) {
+                /*
+                 * If the property value (in ms) is smaller than
+                 * min_timeout, return -EINVAL.
+                 */
+                if (*value < wdd.min_timeout * 1000)
+                        goto out_hv_unreg;
+
+                /*
+                 * If the property value is smaller than
+                 * default max_timeout  then set watchdog max_timeout to
+                 * the value of the property in seconds.
+                 */
+                if (*value < wdd.max_timeout * 1000)
+                        wdd.max_timeout = *value  / 1000;
+        }
+
+        watchdog_init_timeout(&wdd, timeout, NULL);
+
+        watchdog_set_nowayout(&wdd, nowayout);
+
+        err = watchdog_register_device(&wdd);
+        if (err)
+                goto out_hv_unreg;
+
+        pr_info("initialized (timeout=%ds, nowayout=%d)\n",
+                 wdd.timeout, nowayout);
+
+        mdesc_release(handle);
+
+        return 0;
+
+out_hv_unreg:
+        sun4v_hvapi_unregister(HV_GRP_CORE);
+
+out_release:
+        mdesc_release(handle);
+        return err;
+}
+
+static void __exit sun4v_wdt_exit(void)
+{
+        sun4v_hvapi_unregister(HV_GRP_CORE);
+        watchdog_unregister_device(&wdd);
+}
+
+module_init(sun4v_wdt_init);
+module_exit(sun4v_wdt_exit);
+
+MODULE_AUTHOR("Wim Coekaerts <wim.coekaerts@oracle.com>");
+MODULE_DESCRIPTION("sun4v watchdog driver");
+MODULE_LICENSE("GPL");