Merge git://www.linux-watchdog.org/linux-watchdog

Pull watchdog updates from Wim Van Sebroeck:

 - new drivers for: NI 903x/913x watchdog driver, WinSystems EBC-C384
   watchdog timer and ARM SBSA watchdog driver

 - Support for NCT6102D devices

 - Improvements of the generic watchdog framework (improve restart
   handler, make set_timeout optional, introduce infrastructure
   triggered keepalives, ...

 - improvements on the pnx4008 watchdog driver

 - several smaller fixes and improvements

* git://www.linux-watchdog.org/linux-watchdog: (28 commits)
  watchdog: Ensure that wdd is not dereferenced if NULL
  watchdog: imx2: Convert to use infrastructure triggered keepalives
  watchdog: dw_wdt: Convert to use watchdog infrastructure
  watchdog: Add support for minimum time between heartbeats
  watchdog: Make stop function optional
  watchdog: Introduce WDOG_HW_RUNNING flag
  watchdog: Introduce hardware maximum heartbeat in watchdog core
  watchdog: Make set_timeout function optional
  arm: lpc32xx: remove restart handler
  arm: lpc32xx: phy3250 remove restart hook
  watchdog: pnx4008: restart: support "cmd" from userspace
  watchdog: pnx4008: add support for soft reset
  watchdog: pnx4008: add restart handler
  watchdog: pnx4008: update logging during power-on
  watchdog: tangox_wdt: test clock rate to avoid division by 0
  watchdog: atlas7_wdt: test clock rate to avoid division by 0
  watchdog: s3c2410_wdt: Add max and min timeout values
  Watchdog: introduce ARM SBSA watchdog driver
  Documentation: add sbsa-gwdt driver documentation
  watchdog: Add watchdog timer support for the WinSystems EBC-C384
  ...

Documentation/devicetree/bindings/watchdog/sbsa-gwdt.txt

+* SBSA (Server Base System Architecture) Generic Watchdog
+
+The SBSA Generic Watchdog Timer is used to force a reset of the system
+after two stages of timeout have elapsed.  A detailed definition of the
+watchdog timer can be found in the ARM document: ARM-DEN-0029 - Server
+Base System Architecture (SBSA)
+
+Required properties:
+- compatible: Should at least contain "arm,sbsa-gwdt".
+
+- reg: Each entry specifies the base physical address of a register frame
+  and the length of that frame; currently, two frames must be defined,
+  in this order:
+  1: Watchdog control frame;
+  2: Refresh frame.
+
+- interrupts: Should contain the Watchdog Signal 0 (WS0) SPI (Shared
+  Peripheral Interrupt) number of SBSA Generic Watchdog.
+
+Optional properties
+- timeout-sec: Watchdog timeout values (in seconds).
+
+Example for FVP Foundation Model v8:
+
+watchdog@2a440000 {
+	compatible = "arm,sbsa-gwdt";
+	reg = <0x0 0x2a440000 0 0x1000>,
+	      <0x0 0x2a450000 0 0x1000>;
+	interrupts = <0 27 4>;
+	timeout-sec = <30>;
+};

Documentation/watchdog/watchdog-kernel-api.txt

@@ -52,6 +52,8 @@ struct watchdog_device {
 	unsigned int timeout;
 	unsigned int min_timeout;
 	unsigned int max_timeout;
+	unsigned int min_hw_heartbeat_ms;
+	unsigned int max_hw_heartbeat_ms;
 	struct notifier_block reboot_nb;
 	struct notifier_block restart_nb;
 	void *driver_data;
@@ -73,8 +75,21 @@ It contains following fields:
   additional information about the watchdog timer itself. (Like it's unique name)
 * ops: a pointer to the list of watchdog operations that the watchdog supports.
 * timeout: the watchdog timer's timeout value (in seconds).
+  This is the time after which the system will reboot if user space does
+  not send a heartbeat request if WDOG_ACTIVE is set.
 * min_timeout: the watchdog timer's minimum timeout value (in seconds).
-* max_timeout: the watchdog timer's maximum timeout value (in seconds).
+  If set, the minimum configurable value for 'timeout'.
+* max_timeout: the watchdog timer's maximum timeout value (in seconds),
+  as seen from userspace. If set, the maximum configurable value for
+  'timeout'. Not used if max_hw_heartbeat_ms is non-zero.
+* min_hw_heartbeat_ms: Minimum time between heartbeats sent to the chip,
+  in milli-seconds.
+* max_hw_heartbeat_ms: Maximum hardware heartbeat, in milli-seconds.
+  If set, the infrastructure will send heartbeats to the watchdog driver
+  if 'timeout' is larger than max_hw_heartbeat_ms, unless WDOG_ACTIVE
+  is set and userspace failed to send a heartbeat for at least 'timeout'
+  seconds. max_hw_heartbeat_ms must be set if a driver does not implement
+  the stop function.
 * reboot_nb: notifier block that is registered for reboot notifications, for
   internal use only. If the driver calls watchdog_stop_on_reboot, watchdog core
   will stop the watchdog on such notifications.
@@ -123,17 +138,20 @@ are:
   device.
   The routine needs a pointer to the watchdog timer device structure as a
   parameter. It returns zero on success or a negative errno code for failure.
-* stop: with this routine the watchdog timer device is being stopped.
-  The routine needs a pointer to the watchdog timer device structure as a
-  parameter. It returns zero on success or a negative errno code for failure.
-  Some watchdog timer hardware can only be started and not be stopped. The
-  driver supporting this hardware needs to make sure that a start and stop
-  routine is being provided. This can be done by using a timer in the driver
-  that regularly sends a keepalive ping to the watchdog timer hardware.
 
 Not all watchdog timer hardware supports the same functionality. That's why
 all other routines/operations are optional. They only need to be provided if
 they are supported. These optional routines/operations are:
+* stop: with this routine the watchdog timer device is being stopped.
+  The routine needs a pointer to the watchdog timer device structure as a
+  parameter. It returns zero on success or a negative errno code for failure.
+  Some watchdog timer hardware can only be started and not be stopped. A
+  driver supporting such hardware does not have to implement the stop routine.
+  If a driver has no stop function, the watchdog core will set WDOG_HW_RUNNING
+  and start calling the driver's keepalive pings function after the watchdog
+  device is closed.
+  If a watchdog driver does not implement the stop function, it must set
+  max_hw_heartbeat_ms.
 * ping: this is the routine that sends a keepalive ping to the watchdog timer
   hardware.
   The routine needs a pointer to the watchdog timer device structure as a
@@ -153,9 +171,18 @@ they are supported. These optional routines/operations are:
   and -EIO for "could not write value to the watchdog". On success this
   routine should set the timeout value of the watchdog_device to the
   achieved timeout value (which may be different from the requested one
-  because the watchdog does not necessarily has a 1 second resolution).
+  because the watchdog does not necessarily have a 1 second resolution).
+  Drivers implementing max_hw_heartbeat_ms set the hardware watchdog heartbeat
+  to the minimum of timeout and max_hw_heartbeat_ms. Those drivers set the
+  timeout value of the watchdog_device either to the requested timeout value
+  (if it is larger than max_hw_heartbeat_ms), or to the achieved timeout value.
   (Note: the WDIOF_SETTIMEOUT needs to be set in the options field of the
   watchdog's info structure).
+  If the watchdog driver does not have to perform any action but setting the
+  watchdog_device.timeout, this callback can be omitted.
+  If set_timeout is not provided but, WDIOF_SETTIMEOUT is set, the watchdog
+  infrastructure updates the timeout value of the watchdog_device internally
+  to the requested value.
 * get_timeleft: this routines returns the time that's left before a reset.
 * restart: this routine restarts the machine. It returns 0 on success or a
   negative errno code for failure.
@@ -169,11 +196,19 @@ The 'ref' and 'unref' operations are no longer used and deprecated.
 The status bits should (preferably) be set with the set_bit and clear_bit alike
 bit-operations. The status bits that are defined are:
 * WDOG_ACTIVE: this status bit indicates whether or not a watchdog timer device
-  is active or not. When the watchdog is active after booting, then you should
-  set this status bit (Note: when you register the watchdog timer device with
-  this bit set, then opening /dev/watchdog will skip the start operation)
+  is active or not from user perspective. User space is expected to send
+  heartbeat requests to the driver while this flag is set.
 * WDOG_NO_WAY_OUT: this bit stores the nowayout setting for the watchdog.
   If this bit is set then the watchdog timer will not be able to stop.
+* WDOG_HW_RUNNING: Set by the watchdog driver if the hardware watchdog is
+  running. The bit must be set if the watchdog timer hardware can not be
+  stopped. The bit may also be set if the watchdog timer is running after
+  booting, before the watchdog device is opened. If set, the watchdog
+  infrastructure will send keepalives to the watchdog hardware while
+  WDOG_ACTIVE is not set.
+  Note: when you register the watchdog timer device with this bit set,
+  then opening /dev/watchdog will skip the start operation but send a keepalive
+  request instead.
 
   To set the WDOG_NO_WAY_OUT status bit (before registering your watchdog
   timer device) you can either:

Documentation/watchdog/watchdog-parameters.txt

@@ -200,6 +200,11 @@ mv64x60_wdt:
 nowayout: Watchdog cannot be stopped once started
 	(default=kernel config parameter)
 -------------------------------------------------
+ni903x_wdt:
+timeout: Initial watchdog timeout in seconds (0<timeout<516, default=60)
+nowayout: Watchdog cannot be stopped once started
+	(default=kernel config parameter)
+-------------------------------------------------
 nuc900_wdt:
 heartbeat: Watchdog heartbeats in seconds.
 	(default = 15)
@@ -284,6 +289,13 @@ sbc_fitpc2_wdt:
 margin: Watchdog margin in seconds (default 60s)
 nowayout: Watchdog cannot be stopped once started
 -------------------------------------------------
+sbsa_gwdt:
+timeout: Watchdog timeout in seconds. (default 10s)
+action: Watchdog action at the first stage timeout,
+	set to 0 to ignore, 1 to panic. (default=0)
+nowayout: Watchdog cannot be stopped once started
+	(default=kernel config parameter)
+-------------------------------------------------
 sc1200wdt:
 isapnp: When set to 0 driver ISA PnP support will be disabled (default=1)
 io: io port

MAINTAINERS

@@ -11965,6 +11965,12 @@ M:	David Härdeman <david@hardeman.nu>
 S:	Maintained
 F:	drivers/media/rc/winbond-cir.c
 
+WINSYSTEMS EBC-C384 WATCHDOG DRIVER
+M:	William Breathitt Gray <vilhelm.gray@gmail.com>
+L:	linux-watchdog@vger.kernel.org
+S:	Maintained
+F:	drivers/watchdog/ebc-c384_wdt.c
+
 WINSYSTEMS WS16C48 GPIO DRIVER
 M:	William Breathitt Gray <vilhelm.gray@gmail.com>
 L:	linux-gpio@vger.kernel.org

arch/arm/mach-lpc32xx/common.c

@@ -194,21 +194,6 @@ void __init lpc32xx_map_io(void)
 	iotable_init(lpc32xx_io_desc, ARRAY_SIZE(lpc32xx_io_desc));
 }
 
-void lpc23xx_restart(enum reboot_mode mode, const char *cmd)
-{
-	/* Make sure WDT clocks are enabled */
-	__raw_writel(LPC32XX_CLKPWR_PWMCLK_WDOG_EN,
-		LPC32XX_CLKPWR_TIMER_CLK_CTRL);
-
-	/* Instant assert of RESETOUT_N with pulse length 1mS */
-	__raw_writel(13000, io_p2v(LPC32XX_WDTIM_BASE + 0x18));
-	__raw_writel(0x70, io_p2v(LPC32XX_WDTIM_BASE + 0xC));
-
-	/* Wait for watchdog to reset system */
-	while (1)
-		;
-}
-
 static int __init lpc32xx_check_uid(void)
 {
 	u32 uid[4];

arch/arm/mach-lpc32xx/common.h

@@ -30,7 +30,6 @@ extern void lpc32xx_timer_init(void);
 extern void __init lpc32xx_init_irq(void);
 extern void __init lpc32xx_map_io(void);
 extern void __init lpc32xx_serial_init(void);
-extern void lpc23xx_restart(enum reboot_mode, const char *);
 
 
 /*

arch/arm/mach-lpc32xx/phy3250.c

@@ -262,5 +262,4 @@ DT_MACHINE_START(LPC32XX_DT, "LPC32XX SoC (Flattened Device Tree)")
 	.init_time	= lpc32xx_timer_init,
 	.init_machine	= lpc3250_machine_init,
 	.dt_compat	= lpc32xx_dt_compat,
-	.restart	= lpc23xx_restart,
 MACHINE_END

drivers/watchdog/Kconfig

@@ -202,6 +202,26 @@ config ARM_SP805_WATCHDOG
 	  ARM Primecell SP805 Watchdog timer. This will reboot your system when
 	  the timeout is reached.
 
+config ARM_SBSA_WATCHDOG
+	tristate "ARM SBSA Generic Watchdog"
+	depends on ARM64
+	depends on ARM_ARCH_TIMER
+	select WATCHDOG_CORE
+	help
+	  ARM SBSA Generic Watchdog has two stage timeouts:
+	  the first signal (WS0) is for alerting the system by interrupt,
+	  the second one (WS1) is a real hardware reset.
+	  More details: ARM DEN0029B - Server Base System Architecture (SBSA)
+
+	  This driver can operate ARM SBSA Generic Watchdog as a single stage
+	  or a two stages watchdog, it depends on the module parameter "action".
+
+	  Note: the maximum timeout in the two stages mode is half of that in
+	  the single stage mode.
+
+	  To compile this driver as module, choose M here: The module
+	  will be called sbsa_gwdt.
+
 config ASM9260_WATCHDOG
 	tristate "Alphascale ASM9260 watchdog"
 	depends on MACH_ASM9260
@@ -330,6 +350,7 @@ config SA1100_WATCHDOG
 config DW_WATCHDOG
 	tristate "Synopsys DesignWare watchdog"
 	depends on HAS_IOMEM
+	select WATCHDOG_CORE
 	help
 	  Say Y here if to include support for the Synopsys DesignWare
 	  watchdog timer found in many chips.
@@ -399,6 +420,7 @@ config DAVINCI_WATCHDOG
 config ORION_WATCHDOG
 	tristate "Orion watchdog"
 	depends on ARCH_ORION5X || ARCH_DOVE || MACH_DOVE || ARCH_MVEBU
+	depends on ARM
 	select WATCHDOG_CORE
 	help
 	  Say Y here if to include support for the watchdog timer
@@ -468,6 +490,7 @@ config NUC900_WATCHDOG
 config TS4800_WATCHDOG
 	tristate "TS-4800 Watchdog"
 	depends on HAS_IOMEM && OF
+	depends on SOC_IMX51 || COMPILE_TEST
 	select WATCHDOG_CORE
 	select MFD_SYSCON
 	help
@@ -713,6 +736,15 @@ config ALIM7101_WDT
 
 	  Most people will say N.
 
+config EBC_C384_WDT
+	tristate "WinSystems EBC-C384 Watchdog Timer"
+	depends on X86
+	select WATCHDOG_CORE
+	help
+	  Enables watchdog timer support for the watchdog timer on the
+	  WinSystems EBC-C384 motherboard. The timeout may be configured via
+	  the timeout module parameter.
+
 config F71808E_WDT
 	tristate "Fintek F71808E, F71862FG, F71869, F71882FG and F71889FG Watchdog"
 	depends on X86
@@ -1142,6 +1174,7 @@ config W83627HF_WDT
 		NCT6779
 		NCT6791
 		NCT6792
+		NCT6102D/04D/06D
 
 	  This watchdog simply watches your kernel to make sure it doesn't
 	  freeze, and if it does, it reboots your computer after a certain
@@ -1229,6 +1262,17 @@ config INTEL_MEI_WDT
 	  To compile this driver as a module, choose M here:
 	  the module will be called mei_wdt.
 
+config NI903X_WDT
+	tristate "NI 903x/913x Watchdog"
+	depends on X86 && ACPI
+	select WATCHDOG_CORE
+	---help---
+	  This is the driver for the watchdog timer on the National Instruments
+	  903x/913x real-time controllers.
+
+	  To compile this driver as a module, choose M here: the module will be
+	  called ni903x_wdt.
+
 # M32R Architecture
 
 # M68K Architecture
@@ -1392,10 +1436,12 @@ config BCM7038_WDT
 	tristate "BCM7038 Watchdog"
 	select WATCHDOG_CORE
 	depends on HAS_IOMEM
+	depends on ARCH_BRCMSTB || BMIPS_GENERIC || COMPILE_TEST
 	help
-	 Watchdog driver for the built-in hardware in Broadcom 7038 SoCs.
-
-	 Say 'Y or 'M' here to enable the driver.
+	 Watchdog driver for the built-in hardware in Broadcom 7038 and
+	 later SoCs used in set-top boxes.  BCM7038 was made public
+	 during the 2004 CES, and since then, many Broadcom chips use this
+	 watchdog block, including some cable modem chips.
 
 config IMGPDC_WDT
 	tristate "Imagination Technologies PDC Watchdog Timer"

drivers/watchdog/Makefile

@@ -30,6 +30,7 @@ obj-$(CONFIG_USBPCWATCHDOG) += pcwd_usb.o
 
 # ARM Architecture
 obj-$(CONFIG_ARM_SP805_WATCHDOG) += sp805_wdt.o
+obj-$(CONFIG_ARM_SBSA_WATCHDOG) += sbsa_gwdt.o
 obj-$(CONFIG_ASM9260_WATCHDOG) += asm9260_wdt.o
 obj-$(CONFIG_AT91RM9200_WATCHDOG) += at91rm9200_wdt.o
 obj-$(CONFIG_AT91SAM9X_WATCHDOG) += at91sam9_wdt.o
@@ -88,6 +89,7 @@ obj-$(CONFIG_ACQUIRE_WDT) += acquirewdt.o
 obj-$(CONFIG_ADVANTECH_WDT) += advantechwdt.o
 obj-$(CONFIG_ALIM1535_WDT) += alim1535_wdt.o
 obj-$(CONFIG_ALIM7101_WDT) += alim7101_wdt.o
+obj-$(CONFIG_EBC_C384_WDT) += ebc-c384_wdt.o
 obj-$(CONFIG_F71808E_WDT) += f71808e_wdt.o
 obj-$(CONFIG_SP5100_TCO) += sp5100_tco.o
 obj-$(CONFIG_GEODE_WDT) += geodewdt.o
@@ -127,6 +129,7 @@ obj-$(CONFIG_SBC_EPX_C3_WATCHDOG) += sbc_epx_c3.o
 obj-$(CONFIG_INTEL_SCU_WATCHDOG) += intel_scu_watchdog.o
 obj-$(CONFIG_INTEL_MID_WATCHDOG) += intel-mid_wdt.o
 obj-$(CONFIG_INTEL_MEI_WDT) += mei_wdt.o
+obj-$(CONFIG_NI903X_WDT) += ni903x_wdt.o
 
 # M32R Architecture
 

drivers/watchdog/atlas7_wdt.c

@@ -154,6 +154,11 @@ static int atlas7_wdt_probe(struct platform_device *pdev)
 	writel(0, wdt->base + ATLAS7_WDT_CNT_CTRL);
 
 	wdt->tick_rate = clk_get_rate(clk);
+	if (!wdt->tick_rate) {
+		ret = -EINVAL;
+		goto err1;
+	}
+
 	wdt->clk = clk;
 	atlas7_wdd.min_timeout = 1;
 	atlas7_wdd.max_timeout = UINT_MAX / wdt->tick_rate;

drivers/watchdog/bcm47xx_wdt.c

@@ -87,7 +87,8 @@ static int bcm47xx_wdt_hard_set_timeout(struct watchdog_device *wdd,
 	return 0;
 }
 
-static int bcm47xx_wdt_restart(struct watchdog_device *wdd)
+static int bcm47xx_wdt_restart(struct watchdog_device *wdd,
+			       unsigned long action, void *data)
 {
 	struct bcm47xx_wdt *wdt = bcm47xx_wdt_get(wdd);
 

drivers/watchdog/da9063_wdt.c

@@ -119,7 +119,8 @@ static int da9063_wdt_set_timeout(struct watchdog_device *wdd,
 	return ret;
 }
 
-static int da9063_wdt_restart(struct watchdog_device *wdd)
+static int da9063_wdt_restart(struct watchdog_device *wdd, unsigned long action,
+			      void *data)
 {
 	struct da9063_watchdog *wdt = watchdog_get_drvdata(wdd);
 	int ret;

drivers/watchdog/digicolor_wdt.c

@@ -48,7 +48,8 @@ static void dc_wdt_set(struct dc_wdt *wdt, u32 ticks)
 	spin_unlock_irqrestore(&wdt->lock, flags);
 }
 
-static int dc_wdt_restart(struct watchdog_device *wdog)
+static int dc_wdt_restart(struct watchdog_device *wdog, unsigned long action,
+			  void *data)
 {
 	struct dc_wdt *wdt = watchdog_get_drvdata(wdog);
 

drivers/watchdog/dw_wdt.c

@@ -12,9 +12,8 @@
  * and these are a function of the input clock frequency.
  *
  * The DesignWare watchdog cannot be stopped once it has been started so we
- * use a software timer to implement a ping that will keep the watchdog alive.
- * If we receive an expected close for the watchdog then we keep the timer
- * running, otherwise the timer is stopped and the watchdog will expire.
+ * do not implement a stop function. The watchdog core will continue to send
+ * heartbeat requests after the watchdog device has been closed.
  */
 
 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
@@ -22,12 +21,9 @@
 #include <linux/bitops.h>
 #include <linux/clk.h>
 #include <linux/delay.h>
-#include <linux/device.h>
 #include <linux/err.h>
-#include <linux/fs.h>
 #include <linux/io.h>
 #include <linux/kernel.h>
-#include <linux/miscdevice.h>
 #include <linux/module.h>
 #include <linux/moduleparam.h>
 #include <linux/notifier.h>
@@ -35,8 +31,6 @@
 #include <linux/pm.h>
 #include <linux/platform_device.h>
 #include <linux/reboot.h>
-#include <linux/timer.h>
-#include <linux/uaccess.h>
 #include <linux/watchdog.h>
 
 #define WDOG_CONTROL_REG_OFFSET		    0x00
@@ -57,53 +51,50 @@ module_param(nowayout, bool, 0);
 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started "
 		 "(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
 
-#define WDT_TIMEOUT		(HZ / 2)
-
-static struct {
+struct dw_wdt {
 	void __iomem		*regs;
 	struct clk		*clk;
-	unsigned long		in_use;
-	unsigned long		next_heartbeat;
-	struct timer_list	timer;
-	int			expect_close;
 	struct notifier_block	restart_handler;
-} dw_wdt;
+	struct watchdog_device	wdd;
+};
+
+#define to_dw_wdt(wdd)	container_of(wdd, struct dw_wdt, wdd)
 
-static inline int dw_wdt_is_enabled(void)
+static inline int dw_wdt_is_enabled(struct dw_wdt *dw_wdt)
 {
-	return readl(dw_wdt.regs + WDOG_CONTROL_REG_OFFSET) &
+	return readl(dw_wdt->regs + WDOG_CONTROL_REG_OFFSET) &
 		WDOG_CONTROL_REG_WDT_EN_MASK;
 }
 
-static inline int dw_wdt_top_in_seconds(unsigned top)
+static inline int dw_wdt_top_in_seconds(struct dw_wdt *dw_wdt, unsigned top)
 {
 	/*
 	 * There are 16 possible timeout values in 0..15 where the number of
 	 * cycles is 2 ^ (16 + i) and the watchdog counts down.
 	 */
-	return (1U << (16 + top)) / clk_get_rate(dw_wdt.clk);
+	return (1U << (16 + top)) / clk_get_rate(dw_wdt->clk);
 }
 
-static int dw_wdt_get_top(void)
+static int dw_wdt_get_top(struct dw_wdt *dw_wdt)
 {
-	int top = readl(dw_wdt.regs + WDOG_TIMEOUT_RANGE_REG_OFFSET) & 0xF;
+	int top = readl(dw_wdt->regs + WDOG_TIMEOUT_RANGE_REG_OFFSET) & 0xF;
 
-	return dw_wdt_top_in_seconds(top);
+	return dw_wdt_top_in_seconds(dw_wdt, top);
 }
 
-static inline void dw_wdt_set_next_heartbeat(void)
+static int dw_wdt_ping(struct watchdog_device *wdd)
 {
-	dw_wdt.next_heartbeat = jiffies + dw_wdt_get_top() * HZ;
-}
+	struct dw_wdt *dw_wdt = to_dw_wdt(wdd);
 
-static void dw_wdt_keepalive(void)
-{
-	writel(WDOG_COUNTER_RESTART_KICK_VALUE, dw_wdt.regs +
+	writel(WDOG_COUNTER_RESTART_KICK_VALUE, dw_wdt->regs +
 	       WDOG_COUNTER_RESTART_REG_OFFSET);
+
+	return 0;
 }
 
-static int dw_wdt_set_top(unsigned top_s)
+static int dw_wdt_set_timeout(struct watchdog_device *wdd, unsigned int top_s)
 {
+	struct dw_wdt *dw_wdt = to_dw_wdt(wdd);
 	int i, top_val = DW_WDT_MAX_TOP;
 
 	/*
@@ -111,7 +102,7 @@ static int dw_wdt_set_top(unsigned top_s)
 	 * always look for >=.
 	 */
 	for (i = 0; i <= DW_WDT_MAX_TOP; ++i)
-		if (dw_wdt_top_in_seconds(i) >= top_s) {
+		if (dw_wdt_top_in_seconds(dw_wdt, i) >= top_s) {
 			top_val = i;
 			break;
 		}
@@ -123,33 +114,43 @@ static int dw_wdt_set_top(unsigned top_s)
 	 * effectively get a pat of the watchdog right here.
 	 */
 	writel(top_val | top_val << WDOG_TIMEOUT_RANGE_TOPINIT_SHIFT,
-		dw_wdt.regs + WDOG_TIMEOUT_RANGE_REG_OFFSET);
+	       dw_wdt->regs + WDOG_TIMEOUT_RANGE_REG_OFFSET);
 
-	/*
-	 * Add an explicit pat to handle versions of the watchdog that
-	 * don't have TOPINIT.  This won't hurt on versions that have
-	 * it.
-	 */
-	dw_wdt_keepalive();
+	wdd->timeout = dw_wdt_top_in_seconds(dw_wdt, top_val);
 
-	dw_wdt_set_next_heartbeat();
+	return 0;
+}
+
+static int dw_wdt_start(struct watchdog_device *wdd)
+{
+	struct dw_wdt *dw_wdt = to_dw_wdt(wdd);
+
+	dw_wdt_set_timeout(wdd, wdd->timeout);
 
-	return dw_wdt_top_in_seconds(top_val);
+	set_bit(WDOG_HW_RUNNING, &wdd->status);
+
+	writel(WDOG_CONTROL_REG_WDT_EN_MASK,
+	       dw_wdt->regs + WDOG_CONTROL_REG_OFFSET);
+
+	return 0;
 }
 
 static int dw_wdt_restart_handle(struct notifier_block *this,
-				unsigned long mode, void *cmd)
+				 unsigned long mode, void *cmd)
 {
+	struct dw_wdt *dw_wdt;
 	u32 val;
 
-	writel(0, dw_wdt.regs + WDOG_TIMEOUT_RANGE_REG_OFFSET);
-	val = readl(dw_wdt.regs + WDOG_CONTROL_REG_OFFSET);
+	dw_wdt = container_of(this, struct dw_wdt, restart_handler);
+
+	writel(0, dw_wdt->regs + WDOG_TIMEOUT_RANGE_REG_OFFSET);
+	val = readl(dw_wdt->regs + WDOG_CONTROL_REG_OFFSET);
 	if (val & WDOG_CONTROL_REG_WDT_EN_MASK)
-		writel(WDOG_COUNTER_RESTART_KICK_VALUE, dw_wdt.regs +
-			WDOG_COUNTER_RESTART_REG_OFFSET);
+		writel(WDOG_COUNTER_RESTART_KICK_VALUE,
+		       dw_wdt->regs + WDOG_COUNTER_RESTART_REG_OFFSET);
 	else
 		writel(WDOG_CONTROL_REG_WDT_EN_MASK,
-		       dw_wdt.regs + WDOG_CONTROL_REG_OFFSET);
+		       dw_wdt->regs + WDOG_CONTROL_REG_OFFSET);
 
 	/* wait for reset to assert... */
 	mdelay(500);
@@ -157,74 +158,12 @@ static int dw_wdt_restart_handle(struct notifier_block *this,
 	return NOTIFY_DONE;
 }
 
-static void dw_wdt_ping(unsigned long data)
+static unsigned int dw_wdt_get_timeleft(struct watchdog_device *wdd)
 {
-	if (time_before(jiffies, dw_wdt.next_heartbeat) ||
-	    (!nowayout && !dw_wdt.in_use)) {
-		dw_wdt_keepalive();
-		mod_timer(&dw_wdt.timer, jiffies + WDT_TIMEOUT);
-	} else
-		pr_crit("keepalive missed, machine will reset\n");
-}
-
-static int dw_wdt_open(struct inode *inode, struct file *filp)
-{
-	if (test_and_set_bit(0, &dw_wdt.in_use))
-		return -EBUSY;
-
-	/* Make sure we don't get unloaded. */
-	__module_get(THIS_MODULE);
-
-	if (!dw_wdt_is_enabled()) {
-		/*
-		 * The watchdog is not currently enabled. Set the timeout to
-		 * something reasonable and then start it.
-		 */
-		dw_wdt_set_top(DW_WDT_DEFAULT_SECONDS);
-		writel(WDOG_CONTROL_REG_WDT_EN_MASK,
-		       dw_wdt.regs + WDOG_CONTROL_REG_OFFSET);
-	}
-
-	dw_wdt_set_next_heartbeat();
-
-	return nonseekable_open(inode, filp);
-}
-
-static ssize_t dw_wdt_write(struct file *filp, const char __user *buf,
-			    size_t len, loff_t *offset)
-{
-	if (!len)
-		return 0;
-
-	if (!nowayout) {
-		size_t i;
-
-		dw_wdt.expect_close = 0;
-
-		for (i = 0; i < len; ++i) {
-			char c;
-
-			if (get_user(c, buf + i))
-				return -EFAULT;
-
-			if (c == 'V') {
-				dw_wdt.expect_close = 1;
-				break;
-			}
-		}
-	}
+	struct dw_wdt *dw_wdt = to_dw_wdt(wdd);
 
-	dw_wdt_set_next_heartbeat();
-	dw_wdt_keepalive();
-	mod_timer(&dw_wdt.timer, jiffies + WDT_TIMEOUT);
-
-	return len;
-}
-
-static u32 dw_wdt_time_left(void)
-{
-	return readl(dw_wdt.regs + WDOG_CURRENT_COUNT_REG_OFFSET) /
-		clk_get_rate(dw_wdt.clk);
+	return readl(dw_wdt->regs + WDOG_CURRENT_COUNT_REG_OFFSET) /
+		clk_get_rate(dw_wdt->clk);
 }
 
 static const struct watchdog_info dw_wdt_ident = {
@@ -233,78 +172,33 @@ static const struct watchdog_info dw_wdt_ident = {
 	.identity	= "Synopsys DesignWare Watchdog",
 };
 
-static long dw_wdt_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
-{
-	unsigned long val;
-	int timeout;
-
-	switch (cmd) {
-	case WDIOC_GETSUPPORT:
-		return copy_to_user((void __user *)arg, &dw_wdt_ident,
-				    sizeof(dw_wdt_ident)) ? -EFAULT : 0;
-
-	case WDIOC_GETSTATUS:
-	case WDIOC_GETBOOTSTATUS:
-		return put_user(0, (int __user *)arg);
-
-	case WDIOC_KEEPALIVE:
-		dw_wdt_set_next_heartbeat();
-		return 0;
-
-	case WDIOC_SETTIMEOUT:
-		if (get_user(val, (int __user *)arg))
-			return -EFAULT;
-		timeout = dw_wdt_set_top(val);
-		return put_user(timeout , (int __user *)arg);
-
-	case WDIOC_GETTIMEOUT:
-		return put_user(dw_wdt_get_top(), (int __user *)arg);
-
-	case WDIOC_GETTIMELEFT:
-		/* Get the time left until expiry. */
-		if (get_user(val, (int __user *)arg))
-			return -EFAULT;
-		return put_user(dw_wdt_time_left(), (int __user *)arg);
-
-	default:
-		return -ENOTTY;
-	}
-}
-
-static int dw_wdt_release(struct inode *inode, struct file *filp)
-{
-	clear_bit(0, &dw_wdt.in_use);
-
-	if (!dw_wdt.expect_close) {
-		del_timer(&dw_wdt.timer);
-
-		if (!nowayout)
-			pr_crit("unexpected close, system will reboot soon\n");
-		else
-			pr_crit("watchdog cannot be disabled, system will reboot soon\n");
-	}
-
-	dw_wdt.expect_close = 0;
-
-	return 0;
-}
+static const struct watchdog_ops dw_wdt_ops = {
+	.owner		= THIS_MODULE,
+	.start		= dw_wdt_start,
+	.ping		= dw_wdt_ping,
+	.set_timeout	= dw_wdt_set_timeout,
+	.get_timeleft	= dw_wdt_get_timeleft,
+};
 
 #ifdef CONFIG_PM_SLEEP
 static int dw_wdt_suspend(struct device *dev)
 {
-	clk_disable_unprepare(dw_wdt.clk);
+	struct dw_wdt *dw_wdt = dev_get_drvdata(dev);
+
+	clk_disable_unprepare(dw_wdt->clk);
 
 	return 0;
 }
 
 static int dw_wdt_resume(struct device *dev)
 {
-	int err = clk_prepare_enable(dw_wdt.clk);
+	struct dw_wdt *dw_wdt = dev_get_drvdata(dev);
+	int err = clk_prepare_enable(dw_wdt->clk);
 
 	if (err)
 		return err;
 
-	dw_wdt_keepalive();
+	dw_wdt_ping(&dw_wdt->wdd);
 
 	return 0;
 }
@@ -312,67 +206,82 @@ static int dw_wdt_resume(struct device *dev)
 
 static SIMPLE_DEV_PM_OPS(dw_wdt_pm_ops, dw_wdt_suspend, dw_wdt_resume);
 
-static const struct file_operations wdt_fops = {
-	.owner		= THIS_MODULE,
-	.llseek		= no_llseek,
-	.open		= dw_wdt_open,
-	.write		= dw_wdt_write,
-	.unlocked_ioctl	= dw_wdt_ioctl,
-	.release	= dw_wdt_release
-};
-
-static struct miscdevice dw_wdt_miscdev = {
-	.fops		= &wdt_fops,
-	.name		= "watchdog",
-	.minor		= WATCHDOG_MINOR,
-};
-
 static int dw_wdt_drv_probe(struct platform_device *pdev)
 {
+	struct device *dev = &pdev->dev;
+	struct watchdog_device *wdd;
+	struct dw_wdt *dw_wdt;
+	struct resource *mem;
 	int ret;
-	struct resource *mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 
-	dw_wdt.regs = devm_ioremap_resource(&pdev->dev, mem);
-	if (IS_ERR(dw_wdt.regs))
-		return PTR_ERR(dw_wdt.regs);
+	dw_wdt = devm_kzalloc(dev, sizeof(*dw_wdt), GFP_KERNEL);
+	if (!dw_wdt)
+		return -ENOMEM;
+
+	mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	dw_wdt->regs = devm_ioremap_resource(dev, mem);
+	if (IS_ERR(dw_wdt->regs))
+		return PTR_ERR(dw_wdt->regs);
 
-	dw_wdt.clk = devm_clk_get(&pdev->dev, NULL);
-	if (IS_ERR(dw_wdt.clk))
-		return PTR_ERR(dw_wdt.clk);
+	dw_wdt->clk = devm_clk_get(dev, NULL);
+	if (IS_ERR(dw_wdt->clk))
+		return PTR_ERR(dw_wdt->clk);
 
-	ret = clk_prepare_enable(dw_wdt.clk);
+	ret = clk_prepare_enable(dw_wdt->clk);
 	if (ret)
 		return ret;
 
-	ret = misc_register(&dw_wdt_miscdev);
+	wdd = &dw_wdt->wdd;
+	wdd->info = &dw_wdt_ident;
+	wdd->ops = &dw_wdt_ops;
+	wdd->min_timeout = 1;
+	wdd->max_hw_heartbeat_ms =
+		dw_wdt_top_in_seconds(dw_wdt, DW_WDT_MAX_TOP) * 1000;
+	wdd->parent = dev;
+
+	watchdog_set_drvdata(wdd, dw_wdt);
+	watchdog_set_nowayout(wdd, nowayout);
+	watchdog_init_timeout(wdd, 0, dev);
+
+	/*
+	 * If the watchdog is already running, use its already configured
+	 * timeout. Otherwise use the default or the value provided through
+	 * devicetree.
+	 */
+	if (dw_wdt_is_enabled(dw_wdt)) {
+		wdd->timeout = dw_wdt_get_top(dw_wdt);
+		set_bit(WDOG_HW_RUNNING, &wdd->status);
+	} else {
+		wdd->timeout = DW_WDT_DEFAULT_SECONDS;
+		watchdog_init_timeout(wdd, 0, dev);
+	}
+
+	platform_set_drvdata(pdev, dw_wdt);
+
+	ret = watchdog_register_device(wdd);
 	if (ret)
 		goto out_disable_clk;
 
-	dw_wdt.restart_handler.notifier_call = dw_wdt_restart_handle;
-	dw_wdt.restart_handler.priority = 128;
-	ret = register_restart_handler(&dw_wdt.restart_handler);
+	dw_wdt->restart_handler.notifier_call = dw_wdt_restart_handle;
+	dw_wdt->restart_handler.priority = 128;
+	ret = register_restart_handler(&dw_wdt->restart_handler);
 	if (ret)
 		pr_warn("cannot register restart handler\n");
 
-	dw_wdt_set_next_heartbeat();
-	setup_timer(&dw_wdt.timer, dw_wdt_ping, 0);
-	mod_timer(&dw_wdt.timer, jiffies + WDT_TIMEOUT);
-
 	return 0;
 
 out_disable_clk:
-	clk_disable_unprepare(dw_wdt.clk);
-
+	clk_disable_unprepare(dw_wdt->clk);
 	return ret;
 }
 
 static int dw_wdt_drv_remove(struct platform_device *pdev)
 {
-	unregister_restart_handler(&dw_wdt.restart_handler);
-
-	misc_deregister(&dw_wdt_miscdev);
+	struct dw_wdt *dw_wdt = platform_get_drvdata(pdev);
 
-	clk_disable_unprepare(dw_wdt.clk);
+	unregister_restart_handler(&dw_wdt->restart_handler);
+	watchdog_unregister_device(&dw_wdt->wdd);
+	clk_disable_unprepare(dw_wdt->clk);
 
 	return 0;
 }

drivers/watchdog/ebc-c384_wdt.c

+/*
+ * Watchdog timer driver for the WinSystems EBC-C384
+ * Copyright (C) 2016 William Breathitt Gray
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License, version 2, as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ */
+#include <linux/device.h>
+#include <linux/dmi.h>
+#include <linux/errno.h>
+#include <linux/io.h>
+#include <linux/ioport.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include <linux/platform_device.h>
+#include <linux/types.h>
+#include <linux/watchdog.h>
+
+#define MODULE_NAME		"ebc-c384_wdt"
+#define WATCHDOG_TIMEOUT	60
+/*
+ * The timeout value in minutes must fit in a single byte when sent to the
+ * watchdog timer; the maximum timeout possible is 15300 (255 * 60) seconds.
+ */
+#define WATCHDOG_MAX_TIMEOUT	15300
+#define BASE_ADDR		0x564
+#define ADDR_EXTENT		5
+#define CFG_ADDR		(BASE_ADDR + 1)
+#define PET_ADDR		(BASE_ADDR + 2)
+
+static bool nowayout = WATCHDOG_NOWAYOUT;
+module_param(nowayout, bool, 0);
+MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
+	__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
+
+static unsigned timeout;
+module_param(timeout, uint, 0);
+MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds (default="
+	__MODULE_STRING(WATCHDOG_TIMEOUT) ")");
+
+static int ebc_c384_wdt_start(struct watchdog_device *wdev)
+{
+	unsigned t = wdev->timeout;
+
+	/* resolution is in minutes for timeouts greater than 255 seconds */
+	if (t > 255)
+		t = DIV_ROUND_UP(t, 60);
+
+	outb(t, PET_ADDR);
+
+	return 0;
+}
+
+static int ebc_c384_wdt_stop(struct watchdog_device *wdev)
+{
+	outb(0x00, PET_ADDR);
+
+	return 0;
+}
+
+static int ebc_c384_wdt_set_timeout(struct watchdog_device *wdev, unsigned t)
+{
+	/* resolution is in minutes for timeouts greater than 255 seconds */
+	if (t > 255) {
+		/* round second resolution up to minute granularity */
+		wdev->timeout = roundup(t, 60);
+
+		/* set watchdog timer for minutes */
+		outb(0x00, CFG_ADDR);
+	} else {
+		wdev->timeout = t;
+
+		/* set watchdog timer for seconds */
+		outb(0x80, CFG_ADDR);
+	}
+
+	return 0;
+}
+
+static const struct watchdog_ops ebc_c384_wdt_ops = {
+	.start = ebc_c384_wdt_start,
+	.stop = ebc_c384_wdt_stop,
+	.set_timeout = ebc_c384_wdt_set_timeout
+};
+
+static const struct watchdog_info ebc_c384_wdt_info = {
+	.options = WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE | WDIOF_SETTIMEOUT,
+	.identity = MODULE_NAME
+};
+
+static int __init ebc_c384_wdt_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct watchdog_device *wdd;
+
+	if (!devm_request_region(dev, BASE_ADDR, ADDR_EXTENT, dev_name(dev))) {
+		dev_err(dev, "Unable to lock port addresses (0x%X-0x%X)\n",
+			BASE_ADDR, BASE_ADDR + ADDR_EXTENT);
+		return -EBUSY;
+	}
+
+	wdd = devm_kzalloc(dev, sizeof(*wdd), GFP_KERNEL);
+	if (!wdd)
+		return -ENOMEM;
+
+	wdd->info = &ebc_c384_wdt_info;
+	wdd->ops = &ebc_c384_wdt_ops;
+	wdd->timeout = WATCHDOG_TIMEOUT;
+	wdd->min_timeout = 1;
+	wdd->max_timeout = WATCHDOG_MAX_TIMEOUT;
+
+	watchdog_set_nowayout(wdd, nowayout);
+
+	if (watchdog_init_timeout(wdd, timeout, dev))
+		dev_warn(dev, "Invalid timeout (%u seconds), using default (%u seconds)\n",
+			timeout, WATCHDOG_TIMEOUT);
+
+	platform_set_drvdata(pdev, wdd);
+
+	return watchdog_register_device(wdd);
+}
+
+static int ebc_c384_wdt_remove(struct platform_device *pdev)
+{
+	struct watchdog_device *wdd = platform_get_drvdata(pdev);
+
+	watchdog_unregister_device(wdd);
+
+	return 0;
+}
+
+static struct platform_driver ebc_c384_wdt_driver = {
+	.driver = {
+		.name = MODULE_NAME
+	},
+	.remove = ebc_c384_wdt_remove
+};
+
+static struct platform_device *ebc_c384_wdt_device;
+
+static int __init ebc_c384_wdt_init(void)
+{
+	int err;
+
+	if (!dmi_match(DMI_BOARD_NAME, "EBC-C384 SBC"))
+		return -ENODEV;
+
+	ebc_c384_wdt_device = platform_device_alloc(MODULE_NAME, -1);
+	if (!ebc_c384_wdt_device)
+		return -ENOMEM;
+
+	err = platform_device_add(ebc_c384_wdt_device);
+	if (err)
+		goto err_platform_device;
+
+	err = platform_driver_probe(&ebc_c384_wdt_driver, ebc_c384_wdt_probe);
+	if (err)
+		goto err_platform_driver;
+
+	return 0;
+
+err_platform_driver:
+	platform_device_del(ebc_c384_wdt_device);
+err_platform_device:
+	platform_device_put(ebc_c384_wdt_device);
+	return err;
+}
+
+static void __exit ebc_c384_wdt_exit(void)
+{
+	platform_device_unregister(ebc_c384_wdt_device);
+	platform_driver_unregister(&ebc_c384_wdt_driver);
+}
+
+module_init(ebc_c384_wdt_init);
+module_exit(ebc_c384_wdt_exit);
+
+MODULE_AUTHOR("William Breathitt Gray <vilhelm.gray@gmail.com>");
+MODULE_DESCRIPTION("WinSystems EBC-C384 watchdog timer driver");
+MODULE_LICENSE("GPL v2");
+MODULE_ALIAS("platform:" MODULE_NAME);

drivers/watchdog/imgpdc_wdt.c

@@ -150,7 +150,8 @@ static int pdc_wdt_start(struct watchdog_device *wdt_dev)
 	return 0;
 }
 
-static int pdc_wdt_restart(struct watchdog_device *wdt_dev)
+static int pdc_wdt_restart(struct watchdog_device *wdt_dev,
+			   unsigned long action, void *data)
 {
 	struct pdc_wdt_dev *wdt = watchdog_get_drvdata(wdt_dev);
 

drivers/watchdog/imx2_wdt.c

@@ -25,14 +25,12 @@
 #include <linux/delay.h>
 #include <linux/init.h>
 #include <linux/io.h>
-#include <linux/jiffies.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/moduleparam.h>
 #include <linux/of_address.h>
 #include <linux/platform_device.h>
 #include <linux/regmap.h>
-#include <linux/timer.h>
 #include <linux/watchdog.h>
 
 #define DRIVER_NAME "imx2-wdt"
@@ -60,7 +58,6 @@
 struct imx2_wdt_device {
 	struct clk *clk;
 	struct regmap *regmap;
-	struct timer_list timer;	/* Pings the watchdog when closed */
 	struct watchdog_device wdog;
 };
 
@@ -80,7 +77,8 @@ static const struct watchdog_info imx2_wdt_info = {
 	.options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE,
 };
 
-static int imx2_wdt_restart(struct watchdog_device *wdog)
+static int imx2_wdt_restart(struct watchdog_device *wdog, unsigned long action,
+			    void *data)
 {
 	struct imx2_wdt_device *wdev = watchdog_get_drvdata(wdog);
 	unsigned int wcr_enable = IMX2_WDT_WCR_WDE;
@@ -146,16 +144,6 @@ static int imx2_wdt_ping(struct watchdog_device *wdog)
 	return 0;
 }
 
-static void imx2_wdt_timer_ping(unsigned long arg)
-{
-	struct watchdog_device *wdog = (struct watchdog_device *)arg;
-	struct imx2_wdt_device *wdev = watchdog_get_drvdata(wdog);
-
-	/* ping it every wdog->timeout / 2 seconds to prevent reboot */
-	imx2_wdt_ping(wdog);
-	mod_timer(&wdev->timer, jiffies + wdog->timeout * HZ / 2);
-}
-
 static int imx2_wdt_set_timeout(struct watchdog_device *wdog,
 				unsigned int new_timeout)
 {
@@ -172,40 +160,19 @@ static int imx2_wdt_start(struct watchdog_device *wdog)
 {
 	struct imx2_wdt_device *wdev = watchdog_get_drvdata(wdog);
 
-	if (imx2_wdt_is_running(wdev)) {
-		/* delete the timer that pings the watchdog after close */
-		del_timer_sync(&wdev->timer);
+	if (imx2_wdt_is_running(wdev))
 		imx2_wdt_set_timeout(wdog, wdog->timeout);
-	} else
+	else
 		imx2_wdt_setup(wdog);
 
-	return imx2_wdt_ping(wdog);
-}
-
-static int imx2_wdt_stop(struct watchdog_device *wdog)
-{
-	/*
-	 * We don't need a clk_disable, it cannot be disabled once started.
-	 * We use a timer to ping the watchdog while /dev/watchdog is closed
-	 */
-	imx2_wdt_timer_ping((unsigned long)wdog);
-	return 0;
-}
-
-static inline void imx2_wdt_ping_if_active(struct watchdog_device *wdog)
-{
-	struct imx2_wdt_device *wdev = watchdog_get_drvdata(wdog);
+	set_bit(WDOG_HW_RUNNING, &wdog->status);
 
-	if (imx2_wdt_is_running(wdev)) {
-		imx2_wdt_set_timeout(wdog, wdog->timeout);
-		imx2_wdt_timer_ping((unsigned long)wdog);
-	}
+	return imx2_wdt_ping(wdog);
 }
 
 static const struct watchdog_ops imx2_wdt_ops = {
 	.owner = THIS_MODULE,
 	.start = imx2_wdt_start,
-	.stop = imx2_wdt_stop,
 	.ping = imx2_wdt_ping,
 	.set_timeout = imx2_wdt_set_timeout,
 	.restart = imx2_wdt_restart,
@@ -253,7 +220,7 @@ static int __init imx2_wdt_probe(struct platform_device *pdev)
 	wdog->info		= &imx2_wdt_info;
 	wdog->ops		= &imx2_wdt_ops;
 	wdog->min_timeout	= 1;
-	wdog->max_timeout	= IMX2_WDT_MAX_TIME;
+	wdog->max_hw_heartbeat_ms = IMX2_WDT_MAX_TIME * 1000;
 	wdog->parent		= &pdev->dev;
 
 	ret = clk_prepare_enable(wdev->clk);
@@ -274,9 +241,10 @@ static int __init imx2_wdt_probe(struct platform_device *pdev)
 	watchdog_set_restart_priority(wdog, 128);
 	watchdog_init_timeout(wdog, timeout, &pdev->dev);
 
-	setup_timer(&wdev->timer, imx2_wdt_timer_ping, (unsigned long)wdog);
-
-	imx2_wdt_ping_if_active(wdog);
+	if (imx2_wdt_is_running(wdev)) {
+		imx2_wdt_set_timeout(wdog, wdog->timeout);
+		set_bit(WDOG_HW_RUNNING, &wdog->status);
+	}
 
 	/*
 	 * Disable the watchdog power down counter at boot. Otherwise the power
@@ -309,7 +277,6 @@ static int __exit imx2_wdt_remove(struct platform_device *pdev)
 	watchdog_unregister_device(wdog);
 
 	if (imx2_wdt_is_running(wdev)) {
-		del_timer_sync(&wdev->timer);
 		imx2_wdt_ping(wdog);
 		dev_crit(&pdev->dev, "Device removed: Expect reboot!\n");
 	}
@@ -323,10 +290,9 @@ static void imx2_wdt_shutdown(struct platform_device *pdev)
 
 	if (imx2_wdt_is_running(wdev)) {
 		/*
-		 * We are running, we need to delete the timer but will
-		 * give max timeout before reboot will take place
+		 * We are running, configure max timeout before reboot
+		 * will take place.
 		 */
-		del_timer_sync(&wdev->timer);
 		imx2_wdt_set_timeout(wdog, IMX2_WDT_MAX_TIME);
 		imx2_wdt_ping(wdog);
 		dev_crit(&pdev->dev, "Device shutdown: Expect reboot!\n");
@@ -344,10 +310,6 @@ static int imx2_wdt_suspend(struct device *dev)
 	if (imx2_wdt_is_running(wdev)) {
 		imx2_wdt_set_timeout(wdog, IMX2_WDT_MAX_TIME);
 		imx2_wdt_ping(wdog);
-
-		/* The watchdog is not active */
-		if (!watchdog_active(wdog))
-			del_timer_sync(&wdev->timer);
 	}
 
 	clk_disable_unprepare(wdev->clk);
@@ -373,19 +335,10 @@ static int imx2_wdt_resume(struct device *dev)
 		 * watchdog again.
 		 */
 		imx2_wdt_setup(wdog);
+	}
+	if (imx2_wdt_is_running(wdev)) {
 		imx2_wdt_set_timeout(wdog, wdog->timeout);
 		imx2_wdt_ping(wdog);
-	} else if (imx2_wdt_is_running(wdev)) {
-		/* Resuming from non-deep sleep state. */
-		imx2_wdt_set_timeout(wdog, wdog->timeout);
-		imx2_wdt_ping(wdog);
-		/*
-		 * But the watchdog is not active, then start
-		 * the timer again.
-		 */
-		if (!watchdog_active(wdog))
-			mod_timer(&wdev->timer,
-				  jiffies + wdog->timeout * HZ / 2);
 	}
 
 	return 0;

drivers/watchdog/lpc18xx_wdt.c

@@ -153,7 +153,8 @@ static int lpc18xx_wdt_start(struct watchdog_device *wdt_dev)
 	return 0;
 }
 
-static int lpc18xx_wdt_restart(struct watchdog_device *wdt_dev)
+static int lpc18xx_wdt_restart(struct watchdog_device *wdt_dev,
+			       unsigned long action, void *data)
 {
 	struct lpc18xx_wdt_dev *lpc18xx_wdt = watchdog_get_drvdata(wdt_dev);
 	unsigned long flags;

drivers/watchdog/meson_wdt.c

@@ -62,7 +62,8 @@ struct meson_wdt_dev {
 	const struct meson_wdt_data *data;
 };
 
-static int meson_wdt_restart(struct watchdog_device *wdt_dev)
+static int meson_wdt_restart(struct watchdog_device *wdt_dev,
+			     unsigned long action, void *data)
 {
 	struct meson_wdt_dev *meson_wdt = watchdog_get_drvdata(wdt_dev);
 	u32 tc_reboot = MESON_WDT_DC_RESET;

drivers/watchdog/moxart_wdt.c

@@ -31,7 +31,8 @@ struct moxart_wdt_dev {
 
 static int heartbeat;
 
-static int moxart_wdt_restart(struct watchdog_device *wdt_dev)
+static int moxart_wdt_restart(struct watchdog_device *wdt_dev,
+			      unsigned long action, void *data)
 {
 	struct moxart_wdt_dev *moxart_wdt = watchdog_get_drvdata(wdt_dev);
 

drivers/watchdog/mtk_wdt.c

@@ -64,7 +64,8 @@ struct mtk_wdt_dev {
 	void __iomem *wdt_base;
 };
 
-static int mtk_wdt_restart(struct watchdog_device *wdt_dev)
+static int mtk_wdt_restart(struct watchdog_device *wdt_dev,
+			   unsigned long action, void *data)
 {
 	struct mtk_wdt_dev *mtk_wdt = watchdog_get_drvdata(wdt_dev);
 	void __iomem *wdt_base;

drivers/watchdog/ni903x_wdt.c

+/*
+ * Copyright (C) 2016 National Instruments Corp.
+ *
+ * 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.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/acpi.h>
+#include <linux/device.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/watchdog.h>
+
+#define NIWD_CONTROL	0x01
+#define NIWD_COUNTER2	0x02
+#define NIWD_COUNTER1	0x03
+#define NIWD_COUNTER0	0x04
+#define NIWD_SEED2	0x05
+#define NIWD_SEED1	0x06
+#define NIWD_SEED0	0x07
+
+#define NIWD_IO_SIZE	0x08
+
+#define NIWD_CONTROL_MODE		0x80
+#define NIWD_CONTROL_PROC_RESET		0x20
+#define NIWD_CONTROL_PET		0x10
+#define NIWD_CONTROL_RUNNING		0x08
+#define NIWD_CONTROL_CAPTURECOUNTER	0x04
+#define NIWD_CONTROL_RESET		0x02
+#define NIWD_CONTROL_ALARM		0x01
+
+#define NIWD_PERIOD_NS		30720
+#define NIWD_MIN_TIMEOUT	1
+#define NIWD_MAX_TIMEOUT	515
+#define NIWD_DEFAULT_TIMEOUT	60
+
+#define NIWD_NAME		"ni903x_wdt"
+
+struct ni903x_wdt {
+	struct device *dev;
+	u16 io_base;
+	struct watchdog_device wdd;
+};
+
+static unsigned int timeout;
+module_param(timeout, uint, 0);
+MODULE_PARM_DESC(timeout,
+		 "Watchdog timeout in seconds. (default="
+		 __MODULE_STRING(NIWD_DEFAULT_TIMEOUT) ")");
+
+static int nowayout = WATCHDOG_NOWAYOUT;
+module_param(nowayout, int, S_IRUGO);
+MODULE_PARM_DESC(nowayout,
+		 "Watchdog cannot be stopped once started (default="
+		 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
+
+static void ni903x_start(struct ni903x_wdt *wdt)
+{
+	u8 control = inb(wdt->io_base + NIWD_CONTROL);
+
+	outb(control | NIWD_CONTROL_RESET, wdt->io_base + NIWD_CONTROL);
+	outb(control | NIWD_CONTROL_PET, wdt->io_base + NIWD_CONTROL);
+}
+
+static int ni903x_wdd_set_timeout(struct watchdog_device *wdd,
+				  unsigned int timeout)
+{
+	struct ni903x_wdt *wdt = watchdog_get_drvdata(wdd);
+	u32 counter = timeout * (1000000000 / NIWD_PERIOD_NS);
+
+	outb(((0x00FF0000 & counter) >> 16), wdt->io_base + NIWD_SEED2);
+	outb(((0x0000FF00 & counter) >> 8), wdt->io_base + NIWD_SEED1);
+	outb((0x000000FF & counter), wdt->io_base + NIWD_SEED0);
+
+	wdd->timeout = timeout;
+
+	return 0;
+}
+
+static unsigned int ni903x_wdd_get_timeleft(struct watchdog_device *wdd)
+{
+	struct ni903x_wdt *wdt = watchdog_get_drvdata(wdd);
+	u8 control, counter0, counter1, counter2;
+	u32 counter;
+
+	control = inb(wdt->io_base + NIWD_CONTROL);
+	control |= NIWD_CONTROL_CAPTURECOUNTER;
+	outb(control, wdt->io_base + NIWD_CONTROL);
+
+	counter2 = inb(wdt->io_base + NIWD_COUNTER2);
+	counter1 = inb(wdt->io_base + NIWD_COUNTER1);
+	counter0 = inb(wdt->io_base + NIWD_COUNTER0);
+
+	counter = (counter2 << 16) | (counter1 << 8) | counter0;
+
+	return counter / (1000000000 / NIWD_PERIOD_NS);
+}
+
+static int ni903x_wdd_ping(struct watchdog_device *wdd)
+{
+	struct ni903x_wdt *wdt = watchdog_get_drvdata(wdd);
+	u8 control;
+
+	control = inb(wdt->io_base + NIWD_CONTROL);
+	outb(control | NIWD_CONTROL_PET, wdt->io_base + NIWD_CONTROL);
+
+	return 0;
+}
+
+static int ni903x_wdd_start(struct watchdog_device *wdd)
+{
+	struct ni903x_wdt *wdt = watchdog_get_drvdata(wdd);
+
+	outb(NIWD_CONTROL_RESET | NIWD_CONTROL_PROC_RESET,
+	     wdt->io_base + NIWD_CONTROL);
+
+	ni903x_wdd_set_timeout(wdd, wdd->timeout);
+	ni903x_start(wdt);
+
+	return 0;
+}
+
+static int ni903x_wdd_stop(struct watchdog_device *wdd)
+{
+	struct ni903x_wdt *wdt = watchdog_get_drvdata(wdd);
+
+	outb(NIWD_CONTROL_RESET, wdt->io_base + NIWD_CONTROL);
+
+	return 0;
+}
+
+static acpi_status ni903x_resources(struct acpi_resource *res, void *data)
+{
+	struct ni903x_wdt *wdt = data;
+	u16 io_size;
+
+	switch (res->type) {
+	case ACPI_RESOURCE_TYPE_IO:
+		if (wdt->io_base != 0) {
+			dev_err(wdt->dev, "too many IO resources\n");
+			return AE_ERROR;
+		}
+
+		wdt->io_base = res->data.io.minimum;
+		io_size = res->data.io.address_length;
+
+		if (io_size < NIWD_IO_SIZE) {
+			dev_err(wdt->dev, "memory region too small\n");
+			return AE_ERROR;
+		}
+
+		if (!devm_request_region(wdt->dev, wdt->io_base, io_size,
+					 NIWD_NAME)) {
+			dev_err(wdt->dev, "failed to get memory region\n");
+			return AE_ERROR;
+		}
+
+		return AE_OK;
+
+	case ACPI_RESOURCE_TYPE_END_TAG:
+	default:
+		/* Ignore unsupported resources, e.g. IRQ */
+		return AE_OK;
+	}
+}
+
+static const struct watchdog_info ni903x_wdd_info = {
+	.options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
+	.identity = "NI Watchdog",
+};
+
+static const struct watchdog_ops ni903x_wdd_ops = {
+	.owner = THIS_MODULE,
+	.start = ni903x_wdd_start,
+	.stop = ni903x_wdd_stop,
+	.ping = ni903x_wdd_ping,
+	.set_timeout = ni903x_wdd_set_timeout,
+	.get_timeleft = ni903x_wdd_get_timeleft,
+};
+
+static int ni903x_acpi_add(struct acpi_device *device)
+{
+	struct device *dev = &device->dev;
+	struct watchdog_device *wdd;
+	struct ni903x_wdt *wdt;
+	acpi_status status;
+	int ret;
+
+	wdt = devm_kzalloc(dev, sizeof(*wdt), GFP_KERNEL);
+	if (!wdt)
+		return -ENOMEM;
+
+	device->driver_data = wdt;
+	wdt->dev = dev;
+
+	status = acpi_walk_resources(device->handle, METHOD_NAME__CRS,
+				     ni903x_resources, wdt);
+	if (ACPI_FAILURE(status) || wdt->io_base == 0) {
+		dev_err(dev, "failed to get resources\n");
+		return -ENODEV;
+	}
+
+	wdd = &wdt->wdd;
+	wdd->info = &ni903x_wdd_info;
+	wdd->ops = &ni903x_wdd_ops;
+	wdd->min_timeout = NIWD_MIN_TIMEOUT;
+	wdd->max_timeout = NIWD_MAX_TIMEOUT;
+	wdd->timeout = NIWD_DEFAULT_TIMEOUT;
+	wdd->parent = dev;
+	watchdog_set_drvdata(wdd, wdt);
+	watchdog_set_nowayout(wdd, nowayout);
+	ret = watchdog_init_timeout(wdd, timeout, dev);
+	if (ret)
+		dev_err(dev, "unable to set timeout value, using default\n");
+
+	ret = watchdog_register_device(wdd);
+	if (ret) {
+		dev_err(dev, "failed to register watchdog\n");
+		return ret;
+	}
+
+	/* Switch from boot mode to user mode */
+	outb(NIWD_CONTROL_RESET | NIWD_CONTROL_MODE,
+	     wdt->io_base + NIWD_CONTROL);
+
+	dev_dbg(dev, "io_base=0x%04X, timeout=%d, nowayout=%d\n",
+		wdt->io_base, timeout, nowayout);
+
+	return 0;
+}
+
+static int ni903x_acpi_remove(struct acpi_device *device)
+{
+	struct ni903x_wdt *wdt = acpi_driver_data(device);
+
+	ni903x_wdd_stop(&wdt->wdd);
+	watchdog_unregister_device(&wdt->wdd);
+
+	return 0;
+}
+
+static const struct acpi_device_id ni903x_device_ids[] = {
+	{"NIC775C", 0},
+	{"", 0},
+};
+MODULE_DEVICE_TABLE(acpi, ni903x_device_ids);
+
+static struct acpi_driver ni903x_acpi_driver = {
+	.name = NIWD_NAME,
+	.ids = ni903x_device_ids,
+	.ops = {
+		.add = ni903x_acpi_add,
+		.remove = ni903x_acpi_remove,
+	},
+};
+
+module_acpi_driver(ni903x_acpi_driver);
+
+MODULE_DESCRIPTION("NI 903x Watchdog");
+MODULE_AUTHOR("Jeff Westfahl <jeff.westfahl@ni.com>");
+MODULE_AUTHOR("Kyle Roeschley <kyle.roeschley@ni.com>");
+MODULE_LICENSE("GPL");

drivers/watchdog/pnx4008_wdt.c

@@ -31,6 +31,8 @@
 #include <linux/slab.h>
 #include <linux/err.h>
 #include <linux/of.h>
+#include <linux/delay.h>
+#include <linux/reboot.h>
 #include <mach/hardware.h>
 
 /* WatchDog Timer - Chapter 23 Page 207 */
@@ -124,6 +126,41 @@ static int pnx4008_wdt_set_timeout(struct watchdog_device *wdd,
 	return 0;
 }
 
+static int pnx4008_restart_handler(struct watchdog_device *wdd,
+				   unsigned long mode, void *cmd)
+{
+	const char *boot_cmd = cmd;
+
+	/*
+	 * Verify if a "cmd" passed from the userspace program rebooting
+	 * the system; if available, handle it.
+	 * - For details, see the 'reboot' syscall in kernel/reboot.c
+	 * - If the received "cmd" is not supported, use the default mode.
+	 */
+	if (boot_cmd) {
+		if (boot_cmd[0] == 'h')
+			mode = REBOOT_HARD;
+		else if (boot_cmd[0] == 's')
+			mode = REBOOT_SOFT;
+	}
+
+	if (mode == REBOOT_SOFT) {
+		/* Force match output active */
+		writel(EXT_MATCH0, WDTIM_EMR(wdt_base));
+		/* Internal reset on match output (RESOUT_N not asserted) */
+		writel(M_RES1, WDTIM_MCTRL(wdt_base));
+	} else {
+		/* Instant assert of RESETOUT_N with pulse length 1mS */
+		writel(13000, WDTIM_PULSE(wdt_base));
+		writel(M_RES2 | RESFRC1 | RESFRC2, WDTIM_MCTRL(wdt_base));
+	}
+
+	/* Wait for watchdog to reset system */
+	mdelay(1000);
+
+	return NOTIFY_DONE;
+}
+
 static const struct watchdog_info pnx4008_wdt_ident = {
 	.options = WDIOF_CARDRESET | WDIOF_MAGICCLOSE |
 	    WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
@@ -135,6 +172,7 @@ static const struct watchdog_ops pnx4008_wdt_ops = {
 	.start = pnx4008_wdt_start,
 	.stop = pnx4008_wdt_stop,
 	.set_timeout = pnx4008_wdt_set_timeout,
+	.restart = pnx4008_restart_handler,
 };
 
 static struct watchdog_device pnx4008_wdd = {
@@ -169,6 +207,7 @@ static int pnx4008_wdt_probe(struct platform_device *pdev)
 			WDIOF_CARDRESET : 0;
 	pnx4008_wdd.parent = &pdev->dev;
 	watchdog_set_nowayout(&pnx4008_wdd, nowayout);
+	watchdog_set_restart_priority(&pnx4008_wdd, 128);
 
 	pnx4008_wdt_stop(&pnx4008_wdd);	/* disable for now */
 
@@ -178,8 +217,7 @@ static int pnx4008_wdt_probe(struct platform_device *pdev)
 		goto disable_clk;
 	}
 
-	dev_info(&pdev->dev, "PNX4008 Watchdog Timer: heartbeat %d sec\n",
-		 pnx4008_wdd.timeout);
+	dev_info(&pdev->dev, "heartbeat %d sec\n", pnx4008_wdd.timeout);
 
 	return 0;
 

drivers/watchdog/qcom-wdt.c

@@ -70,7 +70,8 @@ static int qcom_wdt_set_timeout(struct watchdog_device *wdd,
 	return qcom_wdt_start(wdd);
 }
 
-static int qcom_wdt_restart(struct watchdog_device *wdd)
+static int qcom_wdt_restart(struct watchdog_device *wdd, unsigned long action,
+			    void *data)
 {
 	struct qcom_wdt *wdt = to_qcom_wdt(wdd);
 	u32 timeout;

drivers/watchdog/rc32434_wdt.c

@@ -237,7 +237,7 @@ static long rc32434_wdt_ioctl(struct file *file, unsigned int cmd,
 			return -EINVAL;
 		/* Fall through */
 	case WDIOC_GETTIMEOUT:
-		return copy_to_user(argp, &timeout, sizeof(int));
+		return copy_to_user(argp, &timeout, sizeof(int)) ? -EFAULT : 0;
 	default:
 		return -ENOTTY;
 	}

drivers/watchdog/s3c2410_wdt.c

@@ -47,6 +47,8 @@
 #define S3C2410_WTDAT		0x04
 #define S3C2410_WTCNT		0x08
 
+#define S3C2410_WTCNT_MAXCNT	0xffff
+
 #define S3C2410_WTCON_RSTEN	(1 << 0)
 #define S3C2410_WTCON_INTEN	(1 << 2)
 #define S3C2410_WTCON_ENABLE	(1 << 5)
@@ -56,8 +58,11 @@
 #define S3C2410_WTCON_DIV64	(2 << 3)
 #define S3C2410_WTCON_DIV128	(3 << 3)
 
+#define S3C2410_WTCON_MAXDIV	0x80
+
 #define S3C2410_WTCON_PRESCALE(x)	((x) << 8)
 #define S3C2410_WTCON_PRESCALE_MASK	(0xff << 8)
+#define S3C2410_WTCON_PRESCALE_MAX	0xff
 
 #define CONFIG_S3C2410_WATCHDOG_ATBOOT		(0)
 #define CONFIG_S3C2410_WATCHDOG_DEFAULT_TIME	(15)
@@ -198,6 +203,14 @@ do {							\
 
 /* functions */
 
+static inline unsigned int s3c2410wdt_max_timeout(struct clk *clock)
+{
+	unsigned long freq = clk_get_rate(clock);
+
+	return S3C2410_WTCNT_MAXCNT / (freq / (S3C2410_WTCON_PRESCALE_MAX + 1)
+				       / S3C2410_WTCON_MAXDIV);
+}
+
 static inline struct s3c2410_wdt *freq_to_wdt(struct notifier_block *nb)
 {
 	return container_of(nb, struct s3c2410_wdt, freq_transition);
@@ -349,7 +362,8 @@ static int s3c2410wdt_set_heartbeat(struct watchdog_device *wdd, unsigned timeou
 	return 0;
 }
 
-static int s3c2410wdt_restart(struct watchdog_device *wdd)
+static int s3c2410wdt_restart(struct watchdog_device *wdd, unsigned long action,
+			      void *data)
 {
 	struct s3c2410_wdt *wdt = watchdog_get_drvdata(wdd);
 	void __iomem *wdt_base = wdt->reg_base;
@@ -567,6 +581,9 @@ static int s3c2410wdt_probe(struct platform_device *pdev)
 		return ret;
 	}
 
+	wdt->wdt_device.min_timeout = 1;
+	wdt->wdt_device.max_timeout = s3c2410wdt_max_timeout(wdt->clock);
+
 	ret = s3c2410wdt_cpufreq_register(wdt);
 	if (ret < 0) {
 		dev_err(dev, "failed to register cpufreq\n");

drivers/watchdog/sbsa_gwdt.c

+/*
+ * SBSA(Server Base System Architecture) Generic Watchdog driver
+ *
+ * Copyright (c) 2015, Linaro Ltd.
+ * Author: Fu Wei <fu.wei@linaro.org>
+ *         Suravee Suthikulpanit <Suravee.Suthikulpanit@amd.com>
+ *         Al Stone <al.stone@linaro.org>
+ *         Timur Tabi <timur@codeaurora.org>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License 2 as published
+ * by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * ARM SBSA Generic Watchdog has two stage timeouts:
+ * the first signal (WS0) is for alerting the system by interrupt,
+ * the second one (WS1) is a real hardware reset.
+ * More details about the hardware specification of this device:
+ * ARM DEN0029B - Server Base System Architecture (SBSA)
+ *
+ * This driver can operate ARM SBSA Generic Watchdog as a single stage watchdog
+ * or a two stages watchdog, it's set up by the module parameter "action".
+ * In the single stage mode, when the timeout is reached, your system
+ * will be reset by WS1. The first signal (WS0) is ignored.
+ * In the two stages mode, when the timeout is reached, the first signal (WS0)
+ * will trigger panic. If the system is getting into trouble and cannot be reset
+ * by panic or restart properly by the kdump kernel(if supported), then the
+ * second stage (as long as the first stage) will be reached, system will be
+ * reset by WS1. This function can help administrator to backup the system
+ * context info by panic console output or kdump.
+ *
+ * SBSA GWDT:
+ * if action is 1 (the two stages mode):
+ * |--------WOR-------WS0--------WOR-------WS1
+ * |----timeout-----(panic)----timeout-----reset
+ *
+ * if action is 0 (the single stage mode):
+ * |------WOR-----WS0(ignored)-----WOR------WS1
+ * |--------------timeout-------------------reset
+ *
+ * Note: Since this watchdog timer has two stages, and each stage is determined
+ * by WOR, in the single stage mode, the timeout is (WOR * 2); in the two
+ * stages mode, the timeout is WOR. The maximum timeout in the two stages mode
+ * is half of that in the single stage mode.
+ *
+ */
+
+#include <linux/io.h>
+#include <linux/interrupt.h>
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+#include <linux/platform_device.h>
+#include <linux/uaccess.h>
+#include <linux/watchdog.h>
+#include <asm/arch_timer.h>
+
+#define DRV_NAME		"sbsa-gwdt"
+#define WATCHDOG_NAME		"SBSA Generic Watchdog"
+
+/* SBSA Generic Watchdog register definitions */
+/* refresh frame */
+#define SBSA_GWDT_WRR		0x000
+
+/* control frame */
+#define SBSA_GWDT_WCS		0x000
+#define SBSA_GWDT_WOR		0x008
+#define SBSA_GWDT_WCV		0x010
+
+/* refresh/control frame */
+#define SBSA_GWDT_W_IIDR	0xfcc
+#define SBSA_GWDT_IDR		0xfd0
+
+/* Watchdog Control and Status Register */
+#define SBSA_GWDT_WCS_EN	BIT(0)
+#define SBSA_GWDT_WCS_WS0	BIT(1)
+#define SBSA_GWDT_WCS_WS1	BIT(2)
+
+/**
+ * struct sbsa_gwdt - Internal representation of the SBSA GWDT
+ * @wdd:		kernel watchdog_device structure
+ * @clk:		store the System Counter clock frequency, in Hz.
+ * @refresh_base:	Virtual address of the watchdog refresh frame
+ * @control_base:	Virtual address of the watchdog control frame
+ */
+struct sbsa_gwdt {
+	struct watchdog_device	wdd;
+	u32			clk;
+	void __iomem		*refresh_base;
+	void __iomem		*control_base;
+};
+
+#define DEFAULT_TIMEOUT		10 /* seconds */
+
+static unsigned int timeout;
+module_param(timeout, uint, 0);
+MODULE_PARM_DESC(timeout,
+		 "Watchdog timeout in seconds. (>=0, default="
+		 __MODULE_STRING(DEFAULT_TIMEOUT) ")");
+
+/*
+ * action refers to action taken when watchdog gets WS0
+ * 0 = skip
+ * 1 = panic
+ * defaults to skip (0)
+ */
+static int action;
+module_param(action, int, 0);
+MODULE_PARM_DESC(action, "after watchdog gets WS0 interrupt, do: "
+		 "0 = skip(*)  1 = panic");
+
+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) ")");
+
+/*
+ * watchdog operation functions
+ */
+static int sbsa_gwdt_set_timeout(struct watchdog_device *wdd,
+				 unsigned int timeout)
+{
+	struct sbsa_gwdt *gwdt = watchdog_get_drvdata(wdd);
+
+	wdd->timeout = timeout;
+
+	if (action)
+		writel(gwdt->clk * timeout,
+		       gwdt->control_base + SBSA_GWDT_WOR);
+	else
+		/*
+		 * In the single stage mode, The first signal (WS0) is ignored,
+		 * the timeout is (WOR * 2), so the WOR should be configured
+		 * to half value of timeout.
+		 */
+		writel(gwdt->clk / 2 * timeout,
+		       gwdt->control_base + SBSA_GWDT_WOR);
+
+	return 0;
+}
+
+static unsigned int sbsa_gwdt_get_timeleft(struct watchdog_device *wdd)
+{
+	struct sbsa_gwdt *gwdt = watchdog_get_drvdata(wdd);
+	u64 timeleft = 0;
+
+	/*
+	 * In the single stage mode, if WS0 is deasserted
+	 * (watchdog is in the first stage),
+	 * timeleft = WOR + (WCV - system counter)
+	 */
+	if (!action &&
+	    !(readl(gwdt->control_base + SBSA_GWDT_WCS) & SBSA_GWDT_WCS_WS0))
+		timeleft += readl(gwdt->control_base + SBSA_GWDT_WOR);
+
+	timeleft += readq(gwdt->control_base + SBSA_GWDT_WCV) -
+		    arch_counter_get_cntvct();
+
+	do_div(timeleft, gwdt->clk);
+
+	return timeleft;
+}
+
+static int sbsa_gwdt_keepalive(struct watchdog_device *wdd)
+{
+	struct sbsa_gwdt *gwdt = watchdog_get_drvdata(wdd);
+
+	/*
+	 * Writing WRR for an explicit watchdog refresh.
+	 * You can write anyting (like 0).
+	 */
+	writel(0, gwdt->refresh_base + SBSA_GWDT_WRR);
+
+	return 0;
+}
+
+static unsigned int sbsa_gwdt_status(struct watchdog_device *wdd)
+{
+	struct sbsa_gwdt *gwdt = watchdog_get_drvdata(wdd);
+	u32 status = readl(gwdt->control_base + SBSA_GWDT_WCS);
+
+	/* is the watchdog timer running? */
+	return (status & SBSA_GWDT_WCS_EN) << WDOG_ACTIVE;
+}
+
+static int sbsa_gwdt_start(struct watchdog_device *wdd)
+{
+	struct sbsa_gwdt *gwdt = watchdog_get_drvdata(wdd);
+
+	/* writing WCS will cause an explicit watchdog refresh */
+	writel(SBSA_GWDT_WCS_EN, gwdt->control_base + SBSA_GWDT_WCS);
+
+	return 0;
+}
+
+static int sbsa_gwdt_stop(struct watchdog_device *wdd)
+{
+	struct sbsa_gwdt *gwdt = watchdog_get_drvdata(wdd);
+
+	/* Simply write 0 to WCS to clean WCS_EN bit */
+	writel(0, gwdt->control_base + SBSA_GWDT_WCS);
+
+	return 0;
+}
+
+static irqreturn_t sbsa_gwdt_interrupt(int irq, void *dev_id)
+{
+	panic(WATCHDOG_NAME " timeout");
+
+	return IRQ_HANDLED;
+}
+
+static struct watchdog_info sbsa_gwdt_info = {
+	.identity	= WATCHDOG_NAME,
+	.options	= WDIOF_SETTIMEOUT |
+			  WDIOF_KEEPALIVEPING |
+			  WDIOF_MAGICCLOSE |
+			  WDIOF_CARDRESET,
+};
+
+static struct watchdog_ops sbsa_gwdt_ops = {
+	.owner		= THIS_MODULE,
+	.start		= sbsa_gwdt_start,
+	.stop		= sbsa_gwdt_stop,
+	.status		= sbsa_gwdt_status,
+	.ping		= sbsa_gwdt_keepalive,
+	.set_timeout	= sbsa_gwdt_set_timeout,
+	.get_timeleft	= sbsa_gwdt_get_timeleft,
+};
+
+static int sbsa_gwdt_probe(struct platform_device *pdev)
+{
+	void __iomem *rf_base, *cf_base;
+	struct device *dev = &pdev->dev;
+	struct watchdog_device *wdd;
+	struct sbsa_gwdt *gwdt;
+	struct resource *res;
+	int ret, irq;
+	u32 status;
+
+	gwdt = devm_kzalloc(dev, sizeof(*gwdt), GFP_KERNEL);
+	if (!gwdt)
+		return -ENOMEM;
+	platform_set_drvdata(pdev, gwdt);
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	cf_base = devm_ioremap_resource(dev, res);
+	if (IS_ERR(cf_base))
+		return PTR_ERR(cf_base);
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 1);
+	rf_base = devm_ioremap_resource(dev, res);
+	if (IS_ERR(rf_base))
+		return PTR_ERR(rf_base);
+
+	/*
+	 * Get the frequency of system counter from the cp15 interface of ARM
+	 * Generic timer. We don't need to check it, because if it returns "0",
+	 * system would panic in very early stage.
+	 */
+	gwdt->clk = arch_timer_get_cntfrq();
+	gwdt->refresh_base = rf_base;
+	gwdt->control_base = cf_base;
+
+	wdd = &gwdt->wdd;
+	wdd->parent = dev;
+	wdd->info = &sbsa_gwdt_info;
+	wdd->ops = &sbsa_gwdt_ops;
+	wdd->min_timeout = 1;
+	wdd->max_timeout = U32_MAX / gwdt->clk;
+	wdd->timeout = DEFAULT_TIMEOUT;
+	watchdog_set_drvdata(wdd, gwdt);
+	watchdog_set_nowayout(wdd, nowayout);
+
+	status = readl(cf_base + SBSA_GWDT_WCS);
+	if (status & SBSA_GWDT_WCS_WS1) {
+		dev_warn(dev, "System reset by WDT.\n");
+		wdd->bootstatus |= WDIOF_CARDRESET;
+	}
+
+	if (action) {
+		irq = platform_get_irq(pdev, 0);
+		if (irq < 0) {
+			action = 0;
+			dev_warn(dev, "unable to get ws0 interrupt.\n");
+		} else {
+			/*
+			 * In case there is a pending ws0 interrupt, just ping
+			 * the watchdog before registering the interrupt routine
+			 */
+			writel(0, rf_base + SBSA_GWDT_WRR);
+			if (devm_request_irq(dev, irq, sbsa_gwdt_interrupt, 0,
+					     pdev->name, gwdt)) {
+				action = 0;
+				dev_warn(dev, "unable to request IRQ %d.\n",
+					 irq);
+			}
+		}
+		if (!action)
+			dev_warn(dev, "falling back to single stage mode.\n");
+	}
+	/*
+	 * In the single stage mode, The first signal (WS0) is ignored,
+	 * the timeout is (WOR * 2), so the maximum timeout should be doubled.
+	 */
+	if (!action)
+		wdd->max_timeout *= 2;
+
+	watchdog_init_timeout(wdd, timeout, dev);
+	/*
+	 * Update timeout to WOR.
+	 * Because of the explicit watchdog refresh mechanism,
+	 * it's also a ping, if watchdog is enabled.
+	 */
+	sbsa_gwdt_set_timeout(wdd, wdd->timeout);
+
+	ret = watchdog_register_device(wdd);
+	if (ret)
+		return ret;
+
+	dev_info(dev, "Initialized with %ds timeout @ %u Hz, action=%d.%s\n",
+		 wdd->timeout, gwdt->clk, action,
+		 status & SBSA_GWDT_WCS_EN ? " [enabled]" : "");
+
+	return 0;
+}
+
+static void sbsa_gwdt_shutdown(struct platform_device *pdev)
+{
+	struct sbsa_gwdt *gwdt = platform_get_drvdata(pdev);
+
+	sbsa_gwdt_stop(&gwdt->wdd);
+}
+
+static int sbsa_gwdt_remove(struct platform_device *pdev)
+{
+	struct sbsa_gwdt *gwdt = platform_get_drvdata(pdev);
+
+	watchdog_unregister_device(&gwdt->wdd);
+
+	return 0;
+}
+
+/* Disable watchdog if it is active during suspend */
+static int __maybe_unused sbsa_gwdt_suspend(struct device *dev)
+{
+	struct sbsa_gwdt *gwdt = dev_get_drvdata(dev);
+
+	if (watchdog_active(&gwdt->wdd))
+		sbsa_gwdt_stop(&gwdt->wdd);
+
+	return 0;
+}
+
+/* Enable watchdog if necessary */
+static int __maybe_unused sbsa_gwdt_resume(struct device *dev)
+{
+	struct sbsa_gwdt *gwdt = dev_get_drvdata(dev);
+
+	if (watchdog_active(&gwdt->wdd))
+		sbsa_gwdt_start(&gwdt->wdd);
+
+	return 0;
+}
+
+static const struct dev_pm_ops sbsa_gwdt_pm_ops = {
+	SET_SYSTEM_SLEEP_PM_OPS(sbsa_gwdt_suspend, sbsa_gwdt_resume)
+};
+
+static const struct of_device_id sbsa_gwdt_of_match[] = {
+	{ .compatible = "arm,sbsa-gwdt", },
+	{},
+};
+MODULE_DEVICE_TABLE(of, sbsa_gwdt_of_match);
+
+static const struct platform_device_id sbsa_gwdt_pdev_match[] = {
+	{ .name = DRV_NAME, },
+	{},
+};
+MODULE_DEVICE_TABLE(platform, sbsa_gwdt_pdev_match);
+
+static struct platform_driver sbsa_gwdt_driver = {
+	.driver = {
+		.name = DRV_NAME,
+		.pm = &sbsa_gwdt_pm_ops,
+		.of_match_table = sbsa_gwdt_of_match,
+	},
+	.probe = sbsa_gwdt_probe,
+	.remove = sbsa_gwdt_remove,
+	.shutdown = sbsa_gwdt_shutdown,
+	.id_table = sbsa_gwdt_pdev_match,
+};
+
+module_platform_driver(sbsa_gwdt_driver);
+
+MODULE_DESCRIPTION("SBSA Generic Watchdog Driver");
+MODULE_AUTHOR("Fu Wei <fu.wei@linaro.org>");
+MODULE_AUTHOR("Suravee Suthikulpanit <Suravee.Suthikulpanit@amd.com>");
+MODULE_AUTHOR("Al Stone <al.stone@linaro.org>");
+MODULE_AUTHOR("Timur Tabi <timur@codeaurora.org>");
+MODULE_LICENSE("GPL v2");
+MODULE_ALIAS("platform:" DRV_NAME);

drivers/watchdog/sunxi_wdt.c

@@ -83,7 +83,8 @@ static const int wdt_timeout_map[] = {
 };
 
 
-static int sunxi_wdt_restart(struct watchdog_device *wdt_dev)
+static int sunxi_wdt_restart(struct watchdog_device *wdt_dev,
+			     unsigned long action, void *data)
 {
 	struct sunxi_wdt_dev *sunxi_wdt = watchdog_get_drvdata(wdt_dev);
 	void __iomem *wdt_base = sunxi_wdt->wdt_base;

drivers/watchdog/tangox_wdt.c

@@ -139,6 +139,10 @@ static int tangox_wdt_probe(struct platform_device *pdev)
 		return err;
 
 	dev->clk_rate = clk_get_rate(dev->clk);
+	if (!dev->clk_rate) {
+		err = -EINVAL;
+		goto err;
+	}
 
 	dev->wdt.parent = &pdev->dev;
 	dev->wdt.info = &tangox_wdt_info;
@@ -171,10 +175,8 @@ static int tangox_wdt_probe(struct platform_device *pdev)
 	}
 
 	err = watchdog_register_device(&dev->wdt);
-	if (err) {
-		clk_disable_unprepare(dev->clk);
-		return err;
-	}
+	if (err)
+		goto err;
 
 	platform_set_drvdata(pdev, dev);
 
@@ -187,6 +189,10 @@ static int tangox_wdt_probe(struct platform_device *pdev)
 	dev_info(&pdev->dev, "SMP86xx/SMP87xx watchdog registered\n");
 
 	return 0;
+
+ err:
+	clk_disable_unprepare(dev->clk);
+	return err;
 }
 
 static int tangox_wdt_remove(struct platform_device *pdev)

drivers/watchdog/w83627hf_wdt.c

@@ -45,10 +45,11 @@
 static int wdt_io;
 static int cr_wdt_timeout;	/* WDT timeout register */
 static int cr_wdt_control;	/* WDT control register */
+static int cr_wdt_csr;		/* WDT control & status register */
 
 enum chips { w83627hf, w83627s, w83697hf, w83697ug, w83637hf, w83627thf,
 	     w83687thf, w83627ehf, w83627dhg, w83627uhg, w83667hg, w83627dhg_p,
-	     w83667hg_b, nct6775, nct6776, nct6779, nct6791, nct6792 };
+	     w83667hg_b, nct6775, nct6776, nct6779, nct6791, nct6792, nct6102 };
 
 static int timeout;			/* in seconds */
 module_param(timeout, int, 0);
@@ -92,15 +93,21 @@ MODULE_PARM_DESC(early_disable, "Disable watchdog at boot time (default=0)");
 #define W83667HG_B_ID		0xb3
 #define NCT6775_ID		0xb4
 #define NCT6776_ID		0xc3
+#define NCT6102_ID		0xc4
 #define NCT6779_ID		0xc5
 #define NCT6791_ID		0xc8
 #define NCT6792_ID		0xc9
 
 #define W83627HF_WDT_TIMEOUT	0xf6
 #define W83697HF_WDT_TIMEOUT	0xf4
+#define NCT6102D_WDT_TIMEOUT	0xf1
 
 #define W83627HF_WDT_CONTROL	0xf5
 #define W83697HF_WDT_CONTROL	0xf3
+#define NCT6102D_WDT_CONTROL	0xf0
+
+#define W836X7HF_WDT_CSR	0xf7
+#define NCT6102D_WDT_CSR	0xf2
 
 static void superio_outb(int reg, int val)
 {
@@ -197,6 +204,7 @@ static int w83627hf_init(struct watchdog_device *wdog, enum chips chip)
 	case nct6779:
 	case nct6791:
 	case nct6792:
+	case nct6102:
 		/*
 		 * These chips have a fixed WDTO# output pin (W83627UHG),
 		 * or support more than one WDTO# output pin.
@@ -229,8 +237,8 @@ static int w83627hf_init(struct watchdog_device *wdog, enum chips chip)
 	superio_outb(cr_wdt_control, t);
 
 	/* reset trigger, disable keyboard & mouse turning off watchdog */
-	t = superio_inb(0xF7) & ~0xD0;
-	superio_outb(0xF7, t);
+	t = superio_inb(cr_wdt_csr) & ~0xD0;
+	superio_outb(cr_wdt_csr, t);
 
 	superio_exit();
 
@@ -322,6 +330,7 @@ static int wdt_find(int addr)
 
 	cr_wdt_timeout = W83627HF_WDT_TIMEOUT;
 	cr_wdt_control = W83627HF_WDT_CONTROL;
+	cr_wdt_csr = W836X7HF_WDT_CSR;
 
 	ret = superio_enter();
 	if (ret)
@@ -387,6 +396,12 @@ static int wdt_find(int addr)
 	case NCT6792_ID:
 		ret = nct6792;
 		break;
+	case NCT6102_ID:
+		ret = nct6102;
+		cr_wdt_timeout = NCT6102D_WDT_TIMEOUT;
+		cr_wdt_control = NCT6102D_WDT_CONTROL;
+		cr_wdt_csr = NCT6102D_WDT_CSR;
+		break;
 	case 0xff:
 		ret = -ENODEV;
 		break;
@@ -422,6 +437,7 @@ static int __init wdt_init(void)
 		"NCT6779",
 		"NCT6791",
 		"NCT6792",
+		"NCT6102",
 	};
 
 	wdt_io = 0x2e;

drivers/watchdog/watchdog_core.c

@@ -164,7 +164,7 @@ static int watchdog_restart_notifier(struct notifier_block *nb,
 
 	int ret;
 
-	ret = wdd->ops->restart(wdd);
+	ret = wdd->ops->restart(wdd, action, data);
 	if (ret)
 		return NOTIFY_BAD;
 
@@ -199,7 +199,7 @@ static int __watchdog_register_device(struct watchdog_device *wdd)
 		return -EINVAL;
 
 	/* Mandatory operations need to be supported */
-	if (wdd->ops->start == NULL || wdd->ops->stop == NULL)
+	if (!wdd->ops->start || (!wdd->ops->stop && !wdd->max_hw_heartbeat_ms))
 		return -EINVAL;
 
 	watchdog_check_min_max_timeout(wdd);

drivers/watchdog/watchdog_dev.c

@@ -36,6 +36,7 @@
 #include <linux/errno.h>	/* For the -ENODEV/... values */
 #include <linux/fs.h>		/* For file operations */
 #include <linux/init.h>		/* For __init/__exit/... */
+#include <linux/jiffies.h>	/* For timeout functions */
 #include <linux/kernel.h>	/* For printk/panic/... */
 #include <linux/kref.h>		/* For data references */
 #include <linux/miscdevice.h>	/* For handling misc devices */
@@ -44,6 +45,7 @@
 #include <linux/slab.h>		/* For memory functions */
 #include <linux/types.h>	/* For standard types (like size_t) */
 #include <linux/watchdog.h>	/* For watchdog specific items */
+#include <linux/workqueue.h>	/* For workqueue */
 #include <linux/uaccess.h>	/* For copy_to_user/put_user/... */
 
 #include "watchdog_core.h"
@@ -61,6 +63,9 @@ struct watchdog_core_data {
 	struct cdev cdev;
 	struct watchdog_device *wdd;
 	struct mutex lock;
+	unsigned long last_keepalive;
+	unsigned long last_hw_keepalive;
+	struct delayed_work work;
 	unsigned long status;		/* Internal status bits */
 #define _WDOG_DEV_OPEN		0	/* Opened ? */
 #define _WDOG_ALLOW_RELEASE	1	/* Did we receive the magic char ? */
@@ -71,6 +76,91 @@ static dev_t watchdog_devt;
 /* Reference to watchdog device behind /dev/watchdog */
 static struct watchdog_core_data *old_wd_data;
 
+static struct workqueue_struct *watchdog_wq;
+
+static inline bool watchdog_need_worker(struct watchdog_device *wdd)
+{
+	/* All variables in milli-seconds */
+	unsigned int hm = wdd->max_hw_heartbeat_ms;
+	unsigned int t = wdd->timeout * 1000;
+
+	/*
+	 * A worker to generate heartbeat requests is needed if all of the
+	 * following conditions are true.
+	 * - Userspace activated the watchdog.
+	 * - The driver provided a value for the maximum hardware timeout, and
+	 *   thus is aware that the framework supports generating heartbeat
+	 *   requests.
+	 * - Userspace requests a longer timeout than the hardware can handle.
+	 */
+	return hm && ((watchdog_active(wdd) && t > hm) ||
+		      (t && !watchdog_active(wdd) && watchdog_hw_running(wdd)));
+}
+
+static long watchdog_next_keepalive(struct watchdog_device *wdd)
+{
+	struct watchdog_core_data *wd_data = wdd->wd_data;
+	unsigned int timeout_ms = wdd->timeout * 1000;
+	unsigned long keepalive_interval;
+	unsigned long last_heartbeat;
+	unsigned long virt_timeout;
+	unsigned int hw_heartbeat_ms;
+
+	virt_timeout = wd_data->last_keepalive + msecs_to_jiffies(timeout_ms);
+	hw_heartbeat_ms = min(timeout_ms, wdd->max_hw_heartbeat_ms);
+	keepalive_interval = msecs_to_jiffies(hw_heartbeat_ms / 2);
+
+	if (!watchdog_active(wdd))
+		return keepalive_interval;
+
+	/*
+	 * To ensure that the watchdog times out wdd->timeout seconds
+	 * after the most recent ping from userspace, the last
+	 * worker ping has to come in hw_heartbeat_ms before this timeout.
+	 */
+	last_heartbeat = virt_timeout - msecs_to_jiffies(hw_heartbeat_ms);
+	return min_t(long, last_heartbeat - jiffies, keepalive_interval);
+}
+
+static inline void watchdog_update_worker(struct watchdog_device *wdd)
+{
+	struct watchdog_core_data *wd_data = wdd->wd_data;
+
+	if (watchdog_need_worker(wdd)) {
+		long t = watchdog_next_keepalive(wdd);
+
+		if (t > 0)
+			mod_delayed_work(watchdog_wq, &wd_data->work, t);
+	} else {
+		cancel_delayed_work(&wd_data->work);
+	}
+}
+
+static int __watchdog_ping(struct watchdog_device *wdd)
+{
+	struct watchdog_core_data *wd_data = wdd->wd_data;
+	unsigned long earliest_keepalive = wd_data->last_hw_keepalive +
+				msecs_to_jiffies(wdd->min_hw_heartbeat_ms);
+	int err;
+
+	if (time_is_after_jiffies(earliest_keepalive)) {
+		mod_delayed_work(watchdog_wq, &wd_data->work,
+				 earliest_keepalive - jiffies);
+		return 0;
+	}
+
+	wd_data->last_hw_keepalive = jiffies;
+
+	if (wdd->ops->ping)
+		err = wdd->ops->ping(wdd);  /* ping the watchdog */
+	else
+		err = wdd->ops->start(wdd); /* restart watchdog */
+
+	watchdog_update_worker(wdd);
+
+	return err;
+}
+
 /*
  *	watchdog_ping: ping the watchdog.
  *	@wdd: the watchdog device to ping
@@ -85,17 +175,28 @@ static struct watchdog_core_data *old_wd_data;
 
 static int watchdog_ping(struct watchdog_device *wdd)
 {
-	int err;
+	struct watchdog_core_data *wd_data = wdd->wd_data;
 
-	if (!watchdog_active(wdd))
+	if (!watchdog_active(wdd) && !watchdog_hw_running(wdd))
 		return 0;
 
-	if (wdd->ops->ping)
-		err = wdd->ops->ping(wdd);	/* ping the watchdog */
-	else
-		err = wdd->ops->start(wdd);	/* restart watchdog */
+	wd_data->last_keepalive = jiffies;
+	return __watchdog_ping(wdd);
+}
 
-	return err;
+static void watchdog_ping_work(struct work_struct *work)
+{
+	struct watchdog_core_data *wd_data;
+	struct watchdog_device *wdd;
+
+	wd_data = container_of(to_delayed_work(work), struct watchdog_core_data,
+			       work);
+
+	mutex_lock(&wd_data->lock);
+	wdd = wd_data->wdd;
+	if (wdd && (watchdog_active(wdd) || watchdog_hw_running(wdd)))
+		__watchdog_ping(wdd);
+	mutex_unlock(&wd_data->lock);
 }
 
 /*
@@ -111,14 +212,23 @@ static int watchdog_ping(struct watchdog_device *wdd)
 
 static int watchdog_start(struct watchdog_device *wdd)
 {
+	struct watchdog_core_data *wd_data = wdd->wd_data;
+	unsigned long started_at;
 	int err;
 
 	if (watchdog_active(wdd))
 		return 0;
 
-	err = wdd->ops->start(wdd);
-	if (err == 0)
+	started_at = jiffies;
+	if (watchdog_hw_running(wdd) && wdd->ops->ping)
+		err = wdd->ops->ping(wdd);
+	else
+		err = wdd->ops->start(wdd);
+	if (err == 0) {
 		set_bit(WDOG_ACTIVE, &wdd->status);
+		wd_data->last_keepalive = started_at;
+		watchdog_update_worker(wdd);
+	}
 
 	return err;
 }
@@ -137,7 +247,7 @@ static int watchdog_start(struct watchdog_device *wdd)
 
 static int watchdog_stop(struct watchdog_device *wdd)
 {
-	int err;
+	int err = 0;
 
 	if (!watchdog_active(wdd))
 		return 0;
@@ -148,9 +258,15 @@ static int watchdog_stop(struct watchdog_device *wdd)
 		return -EBUSY;
 	}
 
-	err = wdd->ops->stop(wdd);
-	if (err == 0)
+	if (wdd->ops->stop)
+		err = wdd->ops->stop(wdd);
+	else
+		set_bit(WDOG_HW_RUNNING, &wdd->status);
+
+	if (err == 0) {
 		clear_bit(WDOG_ACTIVE, &wdd->status);
+		watchdog_update_worker(wdd);
+	}
 
 	return err;
 }
@@ -183,13 +299,22 @@ static unsigned int watchdog_get_status(struct watchdog_device *wdd)
 static int watchdog_set_timeout(struct watchdog_device *wdd,
 							unsigned int timeout)
 {
-	if (!wdd->ops->set_timeout || !(wdd->info->options & WDIOF_SETTIMEOUT))
+	int err = 0;
+
+	if (!(wdd->info->options & WDIOF_SETTIMEOUT))
 		return -EOPNOTSUPP;
 
 	if (watchdog_timeout_invalid(wdd, timeout))
 		return -EINVAL;
 
-	return wdd->ops->set_timeout(wdd, timeout);
+	if (wdd->ops->set_timeout)
+		err = wdd->ops->set_timeout(wdd, timeout);
+	else
+		wdd->timeout = timeout;
+
+	watchdog_update_worker(wdd);
+
+	return err;
 }
 
 /*
@@ -538,7 +663,7 @@ static int watchdog_open(struct inode *inode, struct file *file)
 	 * If the /dev/watchdog device is open, we don't want the module
 	 * to be unloaded.
 	 */
-	if (!try_module_get(wdd->ops->owner)) {
+	if (!watchdog_hw_running(wdd) && !try_module_get(wdd->ops->owner)) {
 		err = -EBUSY;
 		goto out_clear;
 	}
@@ -549,7 +674,8 @@ static int watchdog_open(struct inode *inode, struct file *file)
 
 	file->private_data = wd_data;
 
-	kref_get(&wd_data->kref);
+	if (!watchdog_hw_running(wdd))
+		kref_get(&wd_data->kref);
 
 	/* dev/watchdog is a virtual (and thus non-seekable) filesystem */
 	return nonseekable_open(inode, file);
@@ -585,6 +711,7 @@ static int watchdog_release(struct inode *inode, struct file *file)
 	struct watchdog_core_data *wd_data = file->private_data;
 	struct watchdog_device *wdd;
 	int err = -EBUSY;
+	bool running;
 
 	mutex_lock(&wd_data->lock);
 
@@ -609,14 +736,24 @@ static int watchdog_release(struct inode *inode, struct file *file)
 		watchdog_ping(wdd);
 	}
 
+	cancel_delayed_work_sync(&wd_data->work);
+	watchdog_update_worker(wdd);
+
 	/* make sure that /dev/watchdog can be re-opened */
 	clear_bit(_WDOG_DEV_OPEN, &wd_data->status);
 
 done:
+	running = wdd && watchdog_hw_running(wdd);
 	mutex_unlock(&wd_data->lock);
-	/* Allow the owner module to be unloaded again */
-	module_put(wd_data->cdev.owner);
-	kref_put(&wd_data->kref, watchdog_core_data_release);
+	/*
+	 * Allow the owner module to be unloaded again unless the watchdog
+	 * is still running. If the watchdog is still running, it can not
+	 * be stopped, and its driver must not be unloaded.
+	 */
+	if (!running) {
+		module_put(wd_data->cdev.owner);
+		kref_put(&wd_data->kref, watchdog_core_data_release);
+	}
 	return 0;
 }
 
@@ -658,6 +795,11 @@ static int watchdog_cdev_register(struct watchdog_device *wdd, dev_t devno)
 	wd_data->wdd = wdd;
 	wdd->wd_data = wd_data;
 
+	if (!watchdog_wq)
+		return -ENODEV;
+
+	INIT_DELAYED_WORK(&wd_data->work, watchdog_ping_work);
+
 	if (wdd->id == 0) {
 		old_wd_data = wd_data;
 		watchdog_miscdev.parent = wdd->parent;
@@ -688,8 +830,23 @@ static int watchdog_cdev_register(struct watchdog_device *wdd, dev_t devno)
 			old_wd_data = NULL;
 			kref_put(&wd_data->kref, watchdog_core_data_release);
 		}
+		return err;
 	}
-	return err;
+
+	/* Record time of most recent heartbeat as 'just before now'. */
+	wd_data->last_hw_keepalive = jiffies - 1;
+
+	/*
+	 * If the watchdog is running, prevent its driver from being unloaded,
+	 * and schedule an immediate ping.
+	 */
+	if (watchdog_hw_running(wdd)) {
+		__module_get(wdd->ops->owner);
+		kref_get(&wd_data->kref);
+		queue_delayed_work(watchdog_wq, &wd_data->work, 0);
+	}
+
+	return 0;
 }
 
 /*
@@ -715,6 +872,8 @@ static void watchdog_cdev_unregister(struct watchdog_device *wdd)
 	wdd->wd_data = NULL;
 	mutex_unlock(&wd_data->lock);
 
+	cancel_delayed_work_sync(&wd_data->work);
+
 	kref_put(&wd_data->kref, watchdog_core_data_release);
 }
 
@@ -780,6 +939,13 @@ int __init watchdog_dev_init(void)
 {
 	int err;
 
+	watchdog_wq = alloc_workqueue("watchdogd",
+				      WQ_HIGHPRI | WQ_MEM_RECLAIM, 0);
+	if (!watchdog_wq) {
+		pr_err("Failed to create watchdog workqueue\n");
+		return -ENOMEM;
+	}
+
 	err = class_register(&watchdog_class);
 	if (err < 0) {
 		pr_err("couldn't register class\n");
@@ -806,4 +972,5 @@ void __exit watchdog_dev_exit(void)
 {
 	unregister_chrdev_region(watchdog_devt, MAX_DOGS);
 	class_unregister(&watchdog_class);
+	destroy_workqueue(watchdog_wq);
 }

drivers/watchdog/ziirave_wdt.c

@@ -36,7 +36,7 @@
 #define ZIIRAVE_STATE_OFF	0x1
 #define ZIIRAVE_STATE_ON	0x2
 
-static char *ziirave_reasons[] = {"power cycle", "triggered", NULL, NULL,
+static char *ziirave_reasons[] = {"power cycle", "hw watchdog", NULL, NULL,
 				  "host request", NULL, "illegal configuration",
 				  "illegal instruction", "illegal trap",
 				  "unknown"};

include/linux/watchdog.h

@@ -10,8 +10,9 @@
 
 
 #include <linux/bitops.h>
-#include <linux/device.h>
 #include <linux/cdev.h>
+#include <linux/device.h>
+#include <linux/kernel.h>
 #include <linux/notifier.h>
 #include <uapi/linux/watchdog.h>
 
@@ -46,7 +47,7 @@ struct watchdog_ops {
 	unsigned int (*status)(struct watchdog_device *);
 	int (*set_timeout)(struct watchdog_device *, unsigned int);
 	unsigned int (*get_timeleft)(struct watchdog_device *);
-	int (*restart)(struct watchdog_device *);
+	int (*restart)(struct watchdog_device *, unsigned long, void *);
 	long (*ioctl)(struct watchdog_device *, unsigned int, unsigned long);
 };
 
@@ -61,14 +62,21 @@ struct watchdog_ops {
  * @bootstatus:	Status of the watchdog device at boot.
  * @timeout:	The watchdog devices timeout value (in seconds).
  * @min_timeout:The watchdog devices minimum timeout value (in seconds).
- * @max_timeout:The watchdog devices maximum timeout value (in seconds).
+ * @max_timeout:The watchdog devices maximum timeout value (in seconds)
+ *		as configurable from user space. Only relevant if
+ *		max_hw_heartbeat_ms is not provided.
+ * @min_hw_heartbeat_ms:
+ *		Minimum time between heartbeats, in milli-seconds.
+ * @max_hw_heartbeat_ms:
+ *		Hardware limit for maximum timeout, in milli-seconds.
+ *		Replaces max_timeout if specified.
  * @reboot_nb:	The notifier block to stop watchdog on reboot.
  * @restart_nb:	The notifier block to register a restart function.
  * @driver_data:Pointer to the drivers private data.
  * @wd_data:	Pointer to watchdog core internal data.
  * @status:	Field that contains the devices internal status bits.
- * @deferred: entry in wtd_deferred_reg_list which is used to
- *			   register early initialized watchdogs.
+ * @deferred:	Entry in wtd_deferred_reg_list which is used to
+ *		register early initialized watchdogs.
  *
  * The watchdog_device structure contains all information about a
  * watchdog timer device.
@@ -89,6 +97,8 @@ struct watchdog_device {
 	unsigned int timeout;
 	unsigned int min_timeout;
 	unsigned int max_timeout;
+	unsigned int min_hw_heartbeat_ms;
+	unsigned int max_hw_heartbeat_ms;
 	struct notifier_block reboot_nb;
 	struct notifier_block restart_nb;
 	void *driver_data;
@@ -98,6 +108,7 @@ struct watchdog_device {
 #define WDOG_ACTIVE		0	/* Is the watchdog running/active */
 #define WDOG_NO_WAY_OUT		1	/* Is 'nowayout' feature set ? */
 #define WDOG_STOP_ON_REBOOT	2	/* Should be stopped on reboot */
+#define WDOG_HW_RUNNING		3	/* True if HW watchdog running */
 	struct list_head deferred;
 };
 
@@ -110,6 +121,15 @@ static inline bool watchdog_active(struct watchdog_device *wdd)
 	return test_bit(WDOG_ACTIVE, &wdd->status);
 }
 
+/*
+ * Use the following function to check whether or not the hardware watchdog
+ * is running
+ */
+static inline bool watchdog_hw_running(struct watchdog_device *wdd)
+{
+	return test_bit(WDOG_HW_RUNNING, &wdd->status);
+}
+
 /* Use the following function to set the nowayout feature */
 static inline void watchdog_set_nowayout(struct watchdog_device *wdd, bool nowayout)
 {
@@ -128,13 +148,18 @@ static inline bool watchdog_timeout_invalid(struct watchdog_device *wdd, unsigne
 {
 	/*
 	 * The timeout is invalid if
+	 * - the requested value is larger than UINT_MAX / 1000
+	 *   (since internal calculations are done in milli-seconds),
+	 * or
 	 * - the requested value is smaller than the configured minimum timeout,
 	 * or
-	 * - a maximum timeout is configured, and the requested value is larger
-	 *   than the maximum timeout.
+	 * - a maximum hardware timeout is not configured, a maximum timeout
+	 *   is configured, and the requested value is larger than the
+	 *   configured maximum timeout.
 	 */
-	return t < wdd->min_timeout ||
-		(wdd->max_timeout && t > wdd->max_timeout);
+	return t > UINT_MAX / 1000 || t < wdd->min_timeout ||
+		(!wdd->max_hw_heartbeat_ms && wdd->max_timeout &&
+		 t > wdd->max_timeout);
 }
 
 /* Use the following functions to manipulate watchdog driver specific data */