diff mbox

[v7] Add sun4v_wdt watchdog driver

Message ID 1454089178-29836-1-git-send-email-wim.coekaerts@oracle.com
State Accepted
Delegated to: David Miller
Headers show

Commit Message

Wim Coekaerts Jan. 29, 2016, 5:39 p.m. UTC 
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>
---

Change in v7:
  - remove static wdt_max_timeout
  - directly use value in _probe instead of extra variables
    comments around it should make it clear enough
  - add WDIOF_KEEPALIVEPING (oversight)
  - fix typo

Change in v6:
  - Cleanup goto
  - remove timeout checks and rely on watchdog_init_timout()
  - move sun4v_hv_api_register under mdesc similar to ldc.c

Change in v5:
  - After proper review of the hv watchdog api, the hv takes care of
    rounding to multiple of resolution internally so just check
    if it's <= 1 second.
  - Clean up _ping() and simplify _probe() value checking

Change in v4:
  - timeout in seconds
  - call the hv with support for microsecond resolution

Changes in v3:
  - Modify sun4v_mach_set_watchdog to allow for NULL and remove
    time_remaining
  - Cleanup includes
  - Consolidate _start and _ping into _ping since they were the same
  - Fix checkpatch warnings
  - Remove pr_info()s
  - Clean up return codes to be standard kernel return values
  - Consolidate _init and _probe into _init
    Don't use platform_device anymore because this is really
    just a driver that depends on a hv call. This now looks more
    like softdog.
  - Cleanly check for sun4v architecture and remove extra tests
  - Convert to ms timer support and honor resolution
    since most drivers use seconds I added _ms to make it clear
  - Clean up validation against the properties
  - Use sane values for MIN/MAX
---
 Documentation/watchdog/watchdog-parameters.txt |    4 +
 arch/sparc/kernel/hvcalls.S                    |    3 +-
 arch/sparc/kernel/sparc_ksyms_64.c             |    1 +
 drivers/watchdog/Kconfig                       |   11 ++
 drivers/watchdog/Makefile                      |    1 +
 drivers/watchdog/sun4v_wdt.c                   |  191 ++++++++++++++++++++++++
 6 files changed, 210 insertions(+), 1 deletions(-)
 create mode 100644 drivers/watchdog/sun4v_wdt.c

Comments

Julian Calaby Jan. 29, 2016, 10:06 p.m. UTC | #1 
Hi Wim,

On Sat, Jan 30, 2016 at 4:39 AM, Wim Coekaerts <wim.coekaerts@oracle.com> wrote:
> 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>

Looks good to me.

FWIW this is:

Reviewed-by: Julian Calaby <julian.calaby@gmail.com>

> ---
>
> Change in v7:
>   - remove static wdt_max_timeout
>   - directly use value in _probe instead of extra variables
>     comments around it should make it clear enough
>   - add WDIOF_KEEPALIVEPING (oversight)
>   - fix typo
>
> Change in v6:
>   - Cleanup goto
>   - remove timeout checks and rely on watchdog_init_timout()
>   - move sun4v_hv_api_register under mdesc similar to ldc.c
>
> Change in v5:
>   - After proper review of the hv watchdog api, the hv takes care of
>     rounding to multiple of resolution internally so just check
>     if it's <= 1 second.
>   - Clean up _ping() and simplify _probe() value checking
>
> Change in v4:
>   - timeout in seconds
>   - call the hv with support for microsecond resolution
>
> Changes in v3:
>   - Modify sun4v_mach_set_watchdog to allow for NULL and remove
>     time_remaining
>   - Cleanup includes
>   - Consolidate _start and _ping into _ping since they were the same
>   - Fix checkpatch warnings
>   - Remove pr_info()s
>   - Clean up return codes to be standard kernel return values
>   - Consolidate _init and _probe into _init
>     Don't use platform_device anymore because this is really
>     just a driver that depends on a hv call. This now looks more
>     like softdog.
>   - Cleanly check for sun4v architecture and remove extra tests
>   - Convert to ms timer support and honor resolution
>     since most drivers use seconds I added _ms to make it clear
>   - Clean up validation against the properties
>   - Use sane values for MIN/MAX
> ---
>  Documentation/watchdog/watchdog-parameters.txt |    4 +
>  arch/sparc/kernel/hvcalls.S                    |    3 +-
>  arch/sparc/kernel/sparc_ksyms_64.c             |    1 +
>  drivers/watchdog/Kconfig                       |   11 ++
>  drivers/watchdog/Makefile                      |    1 +
>  drivers/watchdog/sun4v_wdt.c                   |  191 ++++++++++++++++++++++++
>  6 files changed, 210 insertions(+), 1 deletions(-)
>  create mode 100644 drivers/watchdog/sun4v_wdt.c
>
> diff --git a/Documentation/watchdog/watchdog-parameters.txt b/Documentation/watchdog/watchdog-parameters.txt
> index 9f9ec9f..4e4b6f1 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 afbaba5..d127130 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 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 4f0e7be..30d38ae 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 f566753..f6a6a38 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 0000000..1467fe5
> --- /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");
> --
> 1.7.1
>
> --
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Guenter Roeck Jan. 29, 2016, 11:06 p.m. UTC | #2 
On 01/29/2016 09:39 AM, Wim Coekaerts wrote:
> 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: Guenter Roeck <linux@roeck-us.net>

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David Miller Jan. 31, 2016, 7:06 p.m. UTC | #3 
From: Wim Coekaerts <wim.coekaerts@oracle.com>
Date: Fri, 29 Jan 2016 09:39:38 -0800

> 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>

Applied, thanks.
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Wim Van Sebroeck March 1, 2016, 3:34 p.m. UTC | #4 
> From: Wim Coekaerts <wim.coekaerts@oracle.com>
> Date: Fri, 29 Jan 2016 09:39:38 -0800
> 
> > 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>
> 
> Applied, thanks.

This also has my signed-off-by as watchdog maintainer.

Signed-off-by: Wim Van Sebroeck <wim@iguana.be>

I presume you will take this via the SUN architecture tree?

Kind regards,
Wim.
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David Miller March 1, 2016, 4:43 p.m. UTC | #5 
From: Wim Van Sebroeck <wim@iguana.be>
Date: Tue, 1 Mar 2016 16:34:37 +0100

>> From: Wim Coekaerts <wim.coekaerts@oracle.com>
>> Date: Fri, 29 Jan 2016 09:39:38 -0800
>> 
>> > 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>
>> 
>> Applied, thanks.
> 
> This also has my signed-off-by as watchdog maintainer.
> 
> Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
> 
> I presume you will take this via the SUN architecture tree?

Yes and I already send a pull request with this in it last night
to Linus.
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diff mbox

Patch

diff --git a/Documentation/watchdog/watchdog-parameters.txt b/Documentation/watchdog/watchdog-parameters.txt
index 9f9ec9f..4e4b6f1 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 afbaba5..d127130 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 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 4f0e7be..30d38ae 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 f566753..f6a6a38 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 0000000..1467fe5
--- /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");