[PATCH v9 0/5] Watchdog: introduce ARM SBSA watchdog driver

[PATCH v9 0/5] Watchdog: introduce ARM SBSA watchdog driver

[fu.wei]

From: Fu Wei <fu.wei@linaro.org>

This patchset:
    (1)Introduce Documentation/devicetree/bindings/watchdog/sbsa-gwdt.txt
    for FDT info of SBSA Generic Watchdog, and give two examples of
    adding SBSA Generic Watchdog device node into the dts files:
    foundation-v8.dts and amd-seattle-soc.dtsi.

    (2)Introduce "pretimeout" into the watchdog framework, and update
    Documentation/watchdog/watchdog-kernel-api.txt to introduce:
        (1)the new elements in the watchdog_device and watchdog_ops struct;
        (2)the new API "watchdog_init_timeouts".

    (3)Introduce ARM SBSA watchdog driver:
        a.Use linux kernel watchdog framework;
        b.Work with FDT on ARM64;
        c.Use "pretimeout" in watchdog framework;
        d.Support getting timeout and pretimeout from parameter and FDT
          at the driver init stage.
        e.In the first timeout, do panic to save system context;
        f.In the second stage, user can still feed the dog without
          cleaning WS0. By this feature, we can avoid the panic infinite
          loops, while backing up a large system context in a server.
        g.In the second stage, can trigger WS1 by setting pretimeout = 0
          if necessary.

This patchset has been tested with watchdog daemon
(ACPI/FDT, module/build-in) on the following platforms:
    (1)ARM Foundation v8 model
    (2)AMD Seattle platform

This patchset has been tested with kdump successfully.

Changelog:
v9: Rebase to latest kernel version(4.3).
    Update the Documentation of sbsa-gwdt device node info of FDT:
        (1) move some introduction to pretimeout patch
        (2) delete WS1 value from "interrupts" of binding documentation,
            since WS1 won't be handled by Linux.

v8: Rebase to latest kernel version(4.3-rc7).
    Separate the patches of GTDT support and arm_arch_timer. This
    clocksource relevant patch will upstreamed in a individual patchset.
    Update all the default timeout and pretimeout to 30s and 60s.
    Improve documentation and inline comments.
    Fix a bug in pretimeout support which makes timeout and pretimeout
    parameters initialization fail.

v7: Rebase to latest kernel version(4.2-rc7).
    Improve FDT support: geting resource by order, instead of name.
    According to the FDT support, Update the example dts file, gtdt.c
    and sbsa_gwdt.c.
    Pass the sparse test, and fix the warning.
    Fix the max_pretimeout and max_timeout value overflow bug.
    Delete the WCV output value.
    

v6: Improve the dtb example files: reduce the register frame size to 4K.
    Improve pretimeout support:
        (1) improve watchdog_init_timeouts function
	(2) rename watchdog_check_min_max_timeouts back to the original name
        (1) improve watchdog_timeout_invalid/watchdog_pretimeout_invalid
    Add the new features in the sbsa_gwdt driver:
	(1) In the second stage, user can feed the dog without cleaning WS0.
	(2) In the second stage, user can trigger WS1 by setting pretimeout = 0.
	(3) expand the max value of pretimeout, in case 10 second is not enough
	    for a kdump kernel reboot in panic.

v5: Improve pretimeout support:
        (1)fix typo in documentation and comments.
	(2)fix the timeout limits validation bug.
    Simplify sbsa_gwdt driver:
	(1)integrate all the registers access functions into caller.

v4: Refactor GTDT support code: remove it from arch/arm64/kernel/acpi.c,
    put it into drivers/acpi/gtdt.c file.
    Integrate the GTDT code of drivers/clocksource/arm_arch_timer.c into
    drivers/acpi/gtdt.c.
    Improve pretimeout support, fix "pretimeout == 0" problem.
    Simplify sbsa_gwdt driver:
        (1)timeout/pretimeout limits setup;
        (2)keepalive function;
        (3)delete "clk == 0" check;
        (4)delete WS0 status bit check in interrupt routine;
        (5)sbsa_gwdt_set_wcv function.

v3: Delete "export arch_timer_get_rate" patch.
    Driver back to use arch_timer_get_cntfrq.
    Improve watchdog_init_timeouts function and update relevant documentation.
    Improve watchdog_timeout_invalid and watchdog_pretimeout_invalid.
    Improve foundation-v8.dts: delete the unnecessary tag of device node.
    Remove "ARM64 || COMPILE_TEST" from Kconfig.
    Add comments in arch/arm64/kernel/acpi.c
    Fix typoes and incorrect comments.

v2: Improve watchdog-kernel-api.txt documentation for pretimeout support.
    Export "arch_timer_get_rate" in arm_arch_timer.c.
    Add watchdog_init_timeouts API for pretimeout support in framework.
    Improve suspend and resume foundation in driver
    Improve timeout/pretimeout values init code in driver.
    Delete unnecessary items of the sbsa_gwdt struct and #define.
    Delete all unnecessary debug info in driver.
    Fix 64bit division bug.
    Use the arch_timer interface to get watchdog clock rate.
    Add MODULE_DEVICE_TABLE for platform device id.
    Fix typoes.

v1: The first version upstream patchset to linux mailing list.

Fu Wei (5):
  Documentation: add sbsa-gwdt driver documentation
  ARM64: add SBSA Generic Watchdog device node in foundation-v8.dts
  ARM64: add SBSA Generic Watchdog device node in amd-seattle-soc.dtsi
  Watchdog: introdouce "pretimeout" into framework
  Watchdog: introduce ARM SBSA watchdog driver

 .../devicetree/bindings/watchdog/sbsa-gwdt.txt     |  34 ++
 Documentation/watchdog/watchdog-kernel-api.txt     |  61 ++-
 Documentation/watchdog/watchdog-parameters.txt     |   6 +
 arch/arm64/boot/dts/amd/amd-seattle-soc.dtsi       |   8 +
 arch/arm64/boot/dts/arm/foundation-v8.dts          |   7 +
 drivers/watchdog/Kconfig                           |  14 +
 drivers/watchdog/Makefile                          |   1 +
 drivers/watchdog/sbsa_gwdt.c                       | 459 +++++++++++++++++++++
 drivers/watchdog/watchdog_core.c                   | 127 ++++--
 drivers/watchdog/watchdog_dev.c                    |  53 +++
 include/linux/watchdog.h                           |  39 +-
 11 files changed, 767 insertions(+), 42 deletions(-)
 create mode 100644 Documentation/devicetree/bindings/watchdog/sbsa-gwdt.txt
 create mode 100644 drivers/watchdog/sbsa_gwdt.c

-- 
2.5.0

[PATCH v9 1/5] Documentation: add sbsa-gwdt driver documentation

[fu.wei]

From: Fu Wei <fu.wei@linaro.org>

The sbsa-gwdt.txt documentation in devicetree/bindings/watchdog is for
introducing SBSA(Server Base System Architecture) Generic Watchdog
device node info into FDT.

Also add sbsa-gwdt introduction in watchdog-parameters.txt

Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Fu Wei <fu.wei@linaro.org>
---
 .../devicetree/bindings/watchdog/sbsa-gwdt.txt     | 34 ++++++++++++++++++++++
 Documentation/watchdog/watchdog-parameters.txt     |  6 ++++
 2 files changed, 40 insertions(+)

diff --git a/Documentation/devicetree/bindings/watchdog/sbsa-gwdt.txt b/Documentation/devicetree/bindings/watchdog/sbsa-gwdt.txt
new file mode 100644
index 0000000..2da63db
--- /dev/null
+++ b/Documentation/devicetree/bindings/watchdog/sbsa-gwdt.txt
@@ -0,0 +1,34 @@
+* 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 and pre-timeout values.
+  If used, at least first timeout value (in seconds) must be provided.
+  A second optional value (in seconds) may also be provided and
+  will be used as the pre-timeout value, if it is given.
+
+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 = <60 30>;
+};
diff --git a/Documentation/watchdog/watchdog-parameters.txt b/Documentation/watchdog/watchdog-parameters.txt
index 9f9ec9f..e62c8c4 100644
--- a/Documentation/watchdog/watchdog-parameters.txt
+++ b/Documentation/watchdog/watchdog-parameters.txt
@@ -284,6 +284,12 @@ 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 60s)
+pretimeout: Watchdog pretimeout in seconds. (default 30s)
+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
-- 
2.5.0

[PATCH v9 2/5] ARM64: add SBSA Generic Watchdog device node in foundation-v8.dts

[fu.wei]

From: Fu Wei <fu.wei@linaro.org>

This can be a example of adding SBSA Generic Watchdog device node
into some dts files for the Soc which contains SBSA Generic Watchdog.

Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Fu Wei <fu.wei@linaro.org>
---
 arch/arm64/boot/dts/arm/foundation-v8.dts | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/arch/arm64/boot/dts/arm/foundation-v8.dts b/arch/arm64/boot/dts/arm/foundation-v8.dts
index 4eac8dc..1a4fc40 100644
--- a/arch/arm64/boot/dts/arm/foundation-v8.dts
+++ b/arch/arm64/boot/dts/arm/foundation-v8.dts
@@ -237,4 +237,11 @@
 			};
 		};
 	};
+	watchdog@2a440000 {
+		compatible = "arm,sbsa-gwdt";
+		reg = <0x0 0x2a440000 0 0x1000>,
+			<0x0 0x2a450000 0 0x1000>;
+		interrupts = <0 27 4>;
+		timeout-sec = <60 30>;
+	};
 };
-- 
2.5.0

[PATCH v9 2/5] ARM64: add SBSA Generic Watchdog device node in foundation-v8.dts

[fu.wei-QSEj5FYQhm4dnm+yROfE0A]

From: Fu Wei <fu.wei-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>

This can be a example of adding SBSA Generic Watchdog device node
into some dts files for the Soc which contains SBSA Generic Watchdog.

Acked-by: Arnd Bergmann <arnd-r2nGTMty4D4@public.gmane.org>
Signed-off-by: Fu Wei <fu.wei-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>
---
 arch/arm64/boot/dts/arm/foundation-v8.dts | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/arch/arm64/boot/dts/arm/foundation-v8.dts b/arch/arm64/boot/dts/arm/foundation-v8.dts
index 4eac8dc..1a4fc40 100644
--- a/arch/arm64/boot/dts/arm/foundation-v8.dts
+++ b/arch/arm64/boot/dts/arm/foundation-v8.dts
@@ -237,4 +237,11 @@
 			};
 		};
 	};
+	watchdog@2a440000 {
+		compatible = "arm,sbsa-gwdt";
+		reg = <0x0 0x2a440000 0 0x1000>,
+			<0x0 0x2a450000 0 0x1000>;
+		interrupts = <0 27 4>;
+		timeout-sec = <60 30>;
+	};
 };
-- 
2.5.0

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[PATCH v9 3/5] ARM64: add SBSA Generic Watchdog device node in amd-seattle-soc.dtsi

[fu.wei]

From: Fu Wei <fu.wei@linaro.org>

This can be a example of adding SBSA Generic Watchdog device node
into some dts files for the Soc which contains SBSA Generic Watchdog.

Acked-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Suravee Suthikulpanit <Suravee.Suthikulpanit@amd.com>
Tested-by: Suravee Suthikulpanit <Suravee.Suthikulpanit@amd.com>
Signed-off-by: Fu Wei <fu.wei@linaro.org>
---
 arch/arm64/boot/dts/amd/amd-seattle-soc.dtsi | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/arch/arm64/boot/dts/amd/amd-seattle-soc.dtsi b/arch/arm64/boot/dts/amd/amd-seattle-soc.dtsi
index 2874d92..f62d60c1 100644
--- a/arch/arm64/boot/dts/amd/amd-seattle-soc.dtsi
+++ b/arch/arm64/boot/dts/amd/amd-seattle-soc.dtsi
@@ -84,6 +84,14 @@
 			clock-names = "uartclk", "apb_pclk";
 		};
 
+		watchdog0: watchdog@e0bb0000 {
+			compatible = "arm,sbsa-gwdt";
+			reg = <0x0 0xe0bc0000 0 0x1000>,
+				<0x0 0xe0bb0000 0 0x1000>;
+			interrupts = <0 337 4>;
+			timeout-sec = <60 30>;
+		};
+
 		spi0: ssp@e1020000 {
 			status = "disabled";
 			compatible = "arm,pl022", "arm,primecell";
-- 
2.5.0

[PATCH v9 4/5] Watchdog: introdouce "pretimeout" into framework

[fu.wei]

From: Fu Wei <fu.wei@linaro.org>

Also update Documentation/watchdog/watchdog-kernel-api.txt to
introduce:
(1)the new elements in the watchdog_device and watchdog_ops struct;
(2)the new API "watchdog_init_timeouts"

Reasons:
(1)kernel already has two watchdog drivers are using "pretimeout":
	drivers/char/ipmi/ipmi_watchdog.c
	drivers/watchdog/kempld_wdt.c(but the definition is different)
(2)some other drivers are going to use this: ARM SBSA Generic Watchdog

Signed-off-by: Fu Wei <fu.wei@linaro.org>
Tested-by: Pratyush Anand <panand@redhat.com>
---
 Documentation/watchdog/watchdog-kernel-api.txt |  61 ++++++++++--
 drivers/watchdog/watchdog_core.c               | 127 +++++++++++++++++++------
 drivers/watchdog/watchdog_dev.c                |  53 +++++++++++
 include/linux/watchdog.h                       |  39 +++++++-
 4 files changed, 238 insertions(+), 42 deletions(-)

diff --git a/Documentation/watchdog/watchdog-kernel-api.txt b/Documentation/watchdog/watchdog-kernel-api.txt
index d8b0d33..c123775 100644
--- a/Documentation/watchdog/watchdog-kernel-api.txt
+++ b/Documentation/watchdog/watchdog-kernel-api.txt
@@ -53,6 +53,9 @@ struct watchdog_device {
 	unsigned int timeout;
 	unsigned int min_timeout;
 	unsigned int max_timeout;
+	unsigned int pretimeout;
+	unsigned int min_pretimeout;
+	unsigned int max_pretimeout;
 	void *driver_data;
 	struct mutex lock;
 	unsigned long status;
@@ -75,6 +78,9 @@ It contains following fields:
 * timeout: the watchdog timer's timeout value (in seconds).
 * min_timeout: the watchdog timer's minimum timeout value (in seconds).
 * max_timeout: the watchdog timer's maximum timeout value (in seconds).
+* pretimeout: the watchdog timer's pretimeout value (in seconds).
+* min_pretimeout: the watchdog timer's minimum pretimeout value (in seconds).
+* max_pretimeout: the watchdog timer's maximum pretimeout value (in seconds).
 * bootstatus: status of the device after booting (reported with watchdog
   WDIOF_* status bits).
 * driver_data: a pointer to the drivers private data of a watchdog device.
@@ -99,6 +105,7 @@ struct watchdog_ops {
 	int (*ping)(struct watchdog_device *);
 	unsigned int (*status)(struct watchdog_device *);
 	int (*set_timeout)(struct watchdog_device *, unsigned int);
+	int (*set_pretimeout)(struct watchdog_device *, unsigned int);
 	unsigned int (*get_timeleft)(struct watchdog_device *);
 	void (*ref)(struct watchdog_device *);
 	void (*unref)(struct watchdog_device *);
@@ -156,13 +163,24 @@ they are supported. These optional routines/operations are:
 * status: this routine checks the status of the watchdog timer device. The
   status of the device is reported with watchdog WDIOF_* status flags/bits.
 * set_timeout: this routine checks and changes the timeout of the watchdog
-  timer device. It returns 0 on success, -EINVAL for "parameter out of range"
-  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).
+  timer device. It returns 0 on success, -EINVAL for "parameter out of
+  range" (e.g., if the driver supports pretimeout, then the requested
+  timeout value must be greater than the pretimeout value) and -EIO for
+  "could not write value to the watchdog". On success this routine will
+  set the timeout value of the watchdog_device to an actual timeout value
+  (which may be different from the requested one because the watchdog does
+  not necessarily have a 1 second resolution).
   (Note: the WDIOF_SETTIMEOUT needs to be set in the options field of the
   watchdog's info structure).
+* set_pretimeout: this routine checks and changes the pretimeout of the
+  watchdog timer device. It returns 0 on success, -EINVAL for "parameter
+  out of range" and -EIO for "could not write value to the watchdog". On
+  success this routine will set the pretimeout value of the
+  watchdog_device to an actual pretimeout value (which may be different
+  from the requested one because the watchdog does not necessarily have a
+  1 second resolution).
+  (Note: the WDIOF_PRETIMEOUT needs to be set in the options field of the
+  watchdog's info structure).
 * get_timeleft: this routines returns the time that's left before a reset.
 * ref: the operation that calls kref_get on the kref of a dynamically
   allocated watchdog_device struct.
@@ -220,14 +238,39 @@ The watchdog_get_drvdata function allows you to retrieve driver specific data.
 The argument of this function is the watchdog device where you want to retrieve
 data from. The function returns the pointer to the driver specific data.
 
+There are three possible sources of driver default timeout values:
+(1) the driver contains hard-coded default values;
+(2) the timeout-sec from the device tree;
+(3) module parameters can be given when the module is loaded.
 To initialize the timeout field, the following function can be used:
 
 extern int watchdog_init_timeout(struct watchdog_device *wdd,
                                   unsigned int timeout_parm, struct device *dev);
 
 The watchdog_init_timeout function allows you to initialize the timeout field
-using the module timeout parameter or by retrieving the timeout-sec property from
-the device tree (if the module timeout parameter is invalid). Best practice is
-to set the default timeout value as timeout value in the watchdog_device and
-then use this function to set the user "preferred" timeout value.
+using the module timeout parameter or by retrieving the first element of
+the timeout-sec property from the device tree (if the module timeout
+parameter is invalid). Best practice is to set the default timeout value
+as the timeout value in the watchdog_device and then use this function to
+set the user preferred timeout value. By this way, if timeout values are
+provided when the module loads, they will take priority. Second priority
+will be the timeout-sec from DTB, and third the hard-coded driver values.
+This routine returns zero on success and a negative errno code for failure.
+
+Some watchdog timers have two stages of timeout (timeout and pretimeout).
+To initialize the timeout and pretimeout fields at the same time, the
+following function can be used:
+
+int watchdog_init_timeouts(struct watchdog_device *wdd,
+                                  unsigned int pretimeout_parm,
+                                  unsigned int timeout_parm,
+                                  struct device *dev);
+
+The watchdog_init_timeouts function allows you to initialize the
+pretimeout and timeout fields using the module pretimeout and timeout
+parameter or by retrieving the elements in the timeout-sec property from
+the device tree (if the module pretimeout and timeout parameter are
+invalid). Best practice is to set the default pretimeout and timeout
+values as pretimeout and timeout values in the watchdog_device and then
+use this function to set the user preferred pretimeout and timeout value.
 This routine returns zero on success and a negative errno code for failure.
diff --git a/drivers/watchdog/watchdog_core.c b/drivers/watchdog/watchdog_core.c
index 1a80594..44918d5 100644
--- a/drivers/watchdog/watchdog_core.c
+++ b/drivers/watchdog/watchdog_core.c
@@ -85,57 +85,126 @@ static void watchdog_deferred_registration_del(struct watchdog_device *wdd)
 static void watchdog_check_min_max_timeout(struct watchdog_device *wdd)
 {
 	/*
-	 * Check that we have valid min and max timeout values, if
-	 * not reset them both to 0 (=not used or unknown)
+	 * Check that we have valid min and max pretimeout and timeout values,
+	 * if not, reset them all to 0 (=not used or unknown)
 	 */
-	if (wdd->min_timeout > wdd->max_timeout) {
-		pr_info("Invalid min and max timeout values, resetting to 0!\n");
+	if (wdd->min_pretimeout > wdd->max_pretimeout ||
+	    wdd->min_timeout > wdd->max_timeout ||
+	    wdd->min_timeout < wdd->min_pretimeout ||
+	    wdd->max_timeout < wdd->max_pretimeout) {
+		pr_info("Invalid min or max timeouts, resetting to 0\n");
+		wdd->min_pretimeout = 0;
+		wdd->max_pretimeout = 0;
 		wdd->min_timeout = 0;
 		wdd->max_timeout = 0;
 	}
 }
 
 /**
- * watchdog_init_timeout() - initialize the timeout field
+ * watchdog_init_timeouts() - initialize the pretimeout and timeout field
+ * @pretimeout_parm: pretimeout module parameter
  * @timeout_parm: timeout module parameter
  * @dev: Device that stores the timeout-sec property
  *
- * Initialize the timeout field of the watchdog_device struct with either the
- * timeout module parameter (if it is valid value) or the timeout-sec property
- * (only if it is a valid value and the timeout_parm is out of bounds).
- * If none of them are valid then we keep the old value (which should normally
- * be the default timeout value.
+ * Initialize the pretimeout and timeout field of the watchdog_device struct
+ * with both the pretimeout and timeout module parameters (if they are valid) or
+ * the timeout-sec property (only if they are valid and the pretimeout_parm or
+ * timeout_parm is out of bounds). If one of them is invalid, then we keep
+ * the old value (which should normally be the default timeout value).
  *
  * A zero is returned on success and -EINVAL for failure.
  */
-int watchdog_init_timeout(struct watchdog_device *wdd,
-				unsigned int timeout_parm, struct device *dev)
+int watchdog_init_timeouts(struct watchdog_device *wdd,
+			   unsigned int pretimeout_parm,
+			   unsigned int timeout_parm,
+			   struct device *dev)
 {
-	unsigned int t = 0;
-	int ret = 0;
+	int ret = 0, length = 0;
+	u32 timeouts[2] = {0};
+	struct property *prop;
 
 	watchdog_check_min_max_timeout(wdd);
 
-	/* try to get the timeout module parameter first */
-	if (!watchdog_timeout_invalid(wdd, timeout_parm) && timeout_parm) {
-		wdd->timeout = timeout_parm;
-		return ret;
-	}
-	if (timeout_parm)
+	/*
+	 * Backup the timeouts of wdd, and set them to the parameters,
+	 * because watchdog_pretimeout_invalid uses wdd->timeout to validate
+	 * the pretimeout_parm, and watchdog_timeout_invalid uses
+	 * wdd->pretimeout to validate timeout_parm.
+	 * if any of parameters is wrong, restore the default values before
+	 * return.
+	 */
+	timeouts[0] = wdd->timeout;
+	timeouts[1] = wdd->pretimeout;
+	wdd->timeout = timeout_parm;
+	wdd->pretimeout = pretimeout_parm;
+
+	/*
+	 * Try to get the pretimeout module parameter first.
+	 * Note: zero is a valid value for pretimeout.
+	 */
+	if (watchdog_pretimeout_invalid(wdd, pretimeout_parm))
 		ret = -EINVAL;
 
-	/* try to get the timeout_sec property */
-	if (dev == NULL || dev->of_node == NULL)
-		return ret;
-	of_property_read_u32(dev->of_node, "timeout-sec", &t);
-	if (!watchdog_timeout_invalid(wdd, t) && t)
-		wdd->timeout = t;
-	else
+	/*
+	 * Try to get the timeout module parameter,
+	 * if it's valid and pretimeout is valid(ret == 0),
+	 * assignment and return zero. Otherwise, try dtb.
+	 */
+	if (timeout_parm && !ret) {
+		if (!watchdog_timeout_invalid(wdd, timeout_parm))
+			return 0;
 		ret = -EINVAL;
+	}
 
-	return ret;
+	/*
+	 * Either at least one of the module parameters is invalid,
+	 * or timeout_parm is 0. Try to get the timeout_sec property.
+	 */
+	if (!dev || !dev->of_node) {
+		wdd->timeout = timeouts[0];
+		wdd->pretimeout = timeouts[1];
+		return ret;
+	}
+
+	/*
+	 * Backup default values to *_parms,
+	 * timeouts[] will be used by of_property_read_u32_array.
+	 */
+	timeout_parm = timeouts[0];
+	pretimeout_parm = timeouts[1];
+
+	prop = of_find_property(dev->of_node, "timeout-sec", &length);
+	if (prop && length > 0 && length <= sizeof(u32) * 2) {
+		of_property_read_u32_array(dev->of_node,
+					   "timeout-sec", timeouts,
+					   length / sizeof(u32));
+		wdd->timeout = timeouts[0];
+		wdd->pretimeout = timeouts[1];
+
+		if (length == sizeof(u32) * 2) {
+			if (watchdog_pretimeout_invalid(wdd, timeouts[1]))
+				goto error;
+			ret = 0;
+		} else {
+			ret = -EINVAL;
+		}
+
+		if (!watchdog_timeout_invalid(wdd, timeouts[0]) &&
+		    timeouts[0]) {
+			if (ret) /* Only one value in "timeout-sec" */
+				wdd->pretimeout = pretimeout_parm;
+			return 0;
+		}
+	}
+
+error:
+	/* restore default values */
+	wdd->timeout = timeout_parm;
+	wdd->pretimeout = pretimeout_parm;
+
+	return -EINVAL;
 }
-EXPORT_SYMBOL_GPL(watchdog_init_timeout);
+EXPORT_SYMBOL_GPL(watchdog_init_timeouts);
 
 static int __watchdog_register_device(struct watchdog_device *wdd)
 {
diff --git a/drivers/watchdog/watchdog_dev.c b/drivers/watchdog/watchdog_dev.c
index 6aaefba..af0777e 100644
--- a/drivers/watchdog/watchdog_dev.c
+++ b/drivers/watchdog/watchdog_dev.c
@@ -218,6 +218,38 @@ out_timeout:
 }
 
 /*
+ *	watchdog_set_pretimeout: set the watchdog timer pretimeout
+ *	@wddev: the watchdog device to set the timeout for
+ *	@pretimeout: pretimeout to set in seconds
+ */
+
+static int watchdog_set_pretimeout(struct watchdog_device *wddev,
+				   unsigned int pretimeout)
+{
+	int err;
+
+	if (!wddev->ops->set_pretimeout ||
+	    !(wddev->info->options & WDIOF_PRETIMEOUT))
+		return -EOPNOTSUPP;
+
+	if (watchdog_pretimeout_invalid(wddev, pretimeout))
+		return -EINVAL;
+
+	mutex_lock(&wddev->lock);
+
+	if (test_bit(WDOG_UNREGISTERED, &wddev->status)) {
+		err = -ENODEV;
+		goto out_pretimeout;
+	}
+
+	err = wddev->ops->set_pretimeout(wddev, pretimeout);
+
+out_pretimeout:
+	mutex_unlock(&wddev->lock);
+	return err;
+}
+
+/*
  *	watchdog_get_timeleft: wrapper to get the time left before a reboot
  *	@wddev: the watchdog device to get the remaining time from
  *	@timeleft: the time that's left
@@ -388,6 +420,27 @@ static long watchdog_ioctl(struct file *file, unsigned int cmd,
 		if (wdd->timeout == 0)
 			return -EOPNOTSUPP;
 		return put_user(wdd->timeout, p);
+	case WDIOC_SETPRETIMEOUT:
+		/* check if we support the pretimeout */
+		if (!(wdd->info->options & WDIOF_PRETIMEOUT))
+			return -EOPNOTSUPP;
+		if (get_user(val, p))
+			return -EFAULT;
+		err = watchdog_set_pretimeout(wdd, val);
+		if (err < 0)
+			return err;
+		/*
+		 * If the watchdog is active then we send a keepalive ping
+		 * to make sure that the watchdog keeps running (and if
+		 * possible that it takes the new pretimeout)
+		 */
+		watchdog_ping(wdd);
+		/* Fall */
+	case WDIOC_GETPRETIMEOUT:
+		/* check if we support the pretimeout */
+		if (wdd->info->options & WDIOF_PRETIMEOUT)
+			return put_user(wdd->pretimeout, p);
+		return -EOPNOTSUPP;
 	case WDIOC_GETTIMELEFT:
 		err = watchdog_get_timeleft(wdd, &val);
 		if (err)
diff --git a/include/linux/watchdog.h b/include/linux/watchdog.h
index d74a0e9..eaea7b0 100644
--- a/include/linux/watchdog.h
+++ b/include/linux/watchdog.h
@@ -25,6 +25,7 @@ struct watchdog_device;
  * @ping:	The routine that sends a keepalive ping to the watchdog device.
  * @status:	The routine that shows the status of the watchdog device.
  * @set_timeout:The routine for setting the watchdog devices timeout value.
+ * @set_pretimeout:The routine for setting the watchdog devices pretimeout value
  * @get_timeleft:The routine that get's the time that's left before a reset.
  * @ref:	The ref operation for dyn. allocated watchdog_device structs
  * @unref:	The unref operation for dyn. allocated watchdog_device structs
@@ -44,6 +45,7 @@ struct watchdog_ops {
 	int (*ping)(struct watchdog_device *);
 	unsigned int (*status)(struct watchdog_device *);
 	int (*set_timeout)(struct watchdog_device *, unsigned int);
+	int (*set_pretimeout)(struct watchdog_device *, unsigned int);
 	unsigned int (*get_timeleft)(struct watchdog_device *);
 	void (*ref)(struct watchdog_device *);
 	void (*unref)(struct watchdog_device *);
@@ -62,6 +64,9 @@ struct watchdog_ops {
  * @timeout:	The watchdog devices timeout value.
  * @min_timeout:The watchdog devices minimum timeout value.
  * @max_timeout:The watchdog devices maximum timeout value.
+ * @pretimeout:	The watchdog devices pretimeout value.
+ * @min_pretimeout:The watchdog devices minimum pretimeout value.
+ * @max_pretimeout:The watchdog devices maximum pretimeout value.
  * @driver-data:Pointer to the drivers private data.
  * @lock:	Lock for watchdog core internal use only.
  * @status:	Field that contains the devices internal status bits.
@@ -88,6 +93,9 @@ struct watchdog_device {
 	unsigned int timeout;
 	unsigned int min_timeout;
 	unsigned int max_timeout;
+	unsigned int pretimeout;
+	unsigned int min_pretimeout;
+	unsigned int max_pretimeout;
 	void *driver_data;
 	struct mutex lock;
 	unsigned long status;
@@ -119,8 +127,22 @@ static inline void watchdog_set_nowayout(struct watchdog_device *wdd, bool noway
 /* Use the following function to check if a timeout value is invalid */
 static inline bool watchdog_timeout_invalid(struct watchdog_device *wdd, unsigned int t)
 {
-	return ((wdd->max_timeout != 0) &&
-		(t < wdd->min_timeout || t > wdd->max_timeout));
+	return (wdd->max_timeout &&
+		(t < wdd->min_timeout || t > wdd->max_timeout)) ||
+	       (wdd->pretimeout && t <= wdd->pretimeout);
+}
+
+/*
+ * Use the following function to check if a pretimeout value is invalid.
+ * It can be "0", that means we don't use pretimeout.
+ * This function returns false, when pretimeout is 0.
+ */
+static inline bool watchdog_pretimeout_invalid(struct watchdog_device *wdd,
+					       unsigned int t)
+{
+	return t && ((wdd->max_pretimeout &&
+		      (t < wdd->min_pretimeout || t > wdd->max_pretimeout)) ||
+		     (wdd->timeout && t >= wdd->timeout));
 }
 
 /* Use the following functions to manipulate watchdog driver specific data */
@@ -135,8 +157,17 @@ static inline void *watchdog_get_drvdata(struct watchdog_device *wdd)
 }
 
 /* drivers/watchdog/watchdog_core.c */
-extern int watchdog_init_timeout(struct watchdog_device *wdd,
-				  unsigned int timeout_parm, struct device *dev);
+int watchdog_init_timeouts(struct watchdog_device *wdd,
+			   unsigned int pretimeout_parm,
+			   unsigned int timeout_parm,
+			   struct device *dev);
+static inline int watchdog_init_timeout(struct watchdog_device *wdd,
+					unsigned int timeout_parm,
+					struct device *dev)
+{
+	return watchdog_init_timeouts(wdd, 0, timeout_parm, dev);
+}
+
 extern int watchdog_register_device(struct watchdog_device *);
 extern void watchdog_unregister_device(struct watchdog_device *);
 
-- 
2.5.0

[PATCH v9 4/5] Watchdog: introdouce "pretimeout" into framework

[fu.wei-QSEj5FYQhm4dnm+yROfE0A]

From: Fu Wei <fu.wei-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>

Also update Documentation/watchdog/watchdog-kernel-api.txt to
introduce:
(1)the new elements in the watchdog_device and watchdog_ops struct;
(2)the new API "watchdog_init_timeouts"

Reasons:
(1)kernel already has two watchdog drivers are using "pretimeout":
	drivers/char/ipmi/ipmi_watchdog.c
	drivers/watchdog/kempld_wdt.c(but the definition is different)
(2)some other drivers are going to use this: ARM SBSA Generic Watchdog

Signed-off-by: Fu Wei <fu.wei-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>
Tested-by: Pratyush Anand <panand-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
---
 Documentation/watchdog/watchdog-kernel-api.txt |  61 ++++++++++--
 drivers/watchdog/watchdog_core.c               | 127 +++++++++++++++++++------
 drivers/watchdog/watchdog_dev.c                |  53 +++++++++++
 include/linux/watchdog.h                       |  39 +++++++-
 4 files changed, 238 insertions(+), 42 deletions(-)

diff --git a/Documentation/watchdog/watchdog-kernel-api.txt b/Documentation/watchdog/watchdog-kernel-api.txt
index d8b0d33..c123775 100644
--- a/Documentation/watchdog/watchdog-kernel-api.txt
+++ b/Documentation/watchdog/watchdog-kernel-api.txt
@@ -53,6 +53,9 @@ struct watchdog_device {
 	unsigned int timeout;
 	unsigned int min_timeout;
 	unsigned int max_timeout;
+	unsigned int pretimeout;
+	unsigned int min_pretimeout;
+	unsigned int max_pretimeout;
 	void *driver_data;
 	struct mutex lock;
 	unsigned long status;
@@ -75,6 +78,9 @@ It contains following fields:
 * timeout: the watchdog timer's timeout value (in seconds).
 * min_timeout: the watchdog timer's minimum timeout value (in seconds).
 * max_timeout: the watchdog timer's maximum timeout value (in seconds).
+* pretimeout: the watchdog timer's pretimeout value (in seconds).
+* min_pretimeout: the watchdog timer's minimum pretimeout value (in seconds).
+* max_pretimeout: the watchdog timer's maximum pretimeout value (in seconds).
 * bootstatus: status of the device after booting (reported with watchdog
   WDIOF_* status bits).
 * driver_data: a pointer to the drivers private data of a watchdog device.
@@ -99,6 +105,7 @@ struct watchdog_ops {
 	int (*ping)(struct watchdog_device *);
 	unsigned int (*status)(struct watchdog_device *);
 	int (*set_timeout)(struct watchdog_device *, unsigned int);
+	int (*set_pretimeout)(struct watchdog_device *, unsigned int);
 	unsigned int (*get_timeleft)(struct watchdog_device *);
 	void (*ref)(struct watchdog_device *);
 	void (*unref)(struct watchdog_device *);
@@ -156,13 +163,24 @@ they are supported. These optional routines/operations are:
 * status: this routine checks the status of the watchdog timer device. The
   status of the device is reported with watchdog WDIOF_* status flags/bits.
 * set_timeout: this routine checks and changes the timeout of the watchdog
-  timer device. It returns 0 on success, -EINVAL for "parameter out of range"
-  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).
+  timer device. It returns 0 on success, -EINVAL for "parameter out of
+  range" (e.g., if the driver supports pretimeout, then the requested
+  timeout value must be greater than the pretimeout value) and -EIO for
+  "could not write value to the watchdog". On success this routine will
+  set the timeout value of the watchdog_device to an actual timeout value
+  (which may be different from the requested one because the watchdog does
+  not necessarily have a 1 second resolution).
   (Note: the WDIOF_SETTIMEOUT needs to be set in the options field of the
   watchdog's info structure).
+* set_pretimeout: this routine checks and changes the pretimeout of the
+  watchdog timer device. It returns 0 on success, -EINVAL for "parameter
+  out of range" and -EIO for "could not write value to the watchdog". On
+  success this routine will set the pretimeout value of the
+  watchdog_device to an actual pretimeout value (which may be different
+  from the requested one because the watchdog does not necessarily have a
+  1 second resolution).
+  (Note: the WDIOF_PRETIMEOUT needs to be set in the options field of the
+  watchdog's info structure).
 * get_timeleft: this routines returns the time that's left before a reset.
 * ref: the operation that calls kref_get on the kref of a dynamically
   allocated watchdog_device struct.
@@ -220,14 +238,39 @@ The watchdog_get_drvdata function allows you to retrieve driver specific data.
 The argument of this function is the watchdog device where you want to retrieve
 data from. The function returns the pointer to the driver specific data.
 
+There are three possible sources of driver default timeout values:
+(1) the driver contains hard-coded default values;
+(2) the timeout-sec from the device tree;
+(3) module parameters can be given when the module is loaded.
 To initialize the timeout field, the following function can be used:
 
 extern int watchdog_init_timeout(struct watchdog_device *wdd,
                                   unsigned int timeout_parm, struct device *dev);
 
 The watchdog_init_timeout function allows you to initialize the timeout field
-using the module timeout parameter or by retrieving the timeout-sec property from
-the device tree (if the module timeout parameter is invalid). Best practice is
-to set the default timeout value as timeout value in the watchdog_device and
-then use this function to set the user "preferred" timeout value.
+using the module timeout parameter or by retrieving the first element of
+the timeout-sec property from the device tree (if the module timeout
+parameter is invalid). Best practice is to set the default timeout value
+as the timeout value in the watchdog_device and then use this function to
+set the user preferred timeout value. By this way, if timeout values are
+provided when the module loads, they will take priority. Second priority
+will be the timeout-sec from DTB, and third the hard-coded driver values.
+This routine returns zero on success and a negative errno code for failure.
+
+Some watchdog timers have two stages of timeout (timeout and pretimeout).
+To initialize the timeout and pretimeout fields at the same time, the
+following function can be used:
+
+int watchdog_init_timeouts(struct watchdog_device *wdd,
+                                  unsigned int pretimeout_parm,
+                                  unsigned int timeout_parm,
+                                  struct device *dev);
+
+The watchdog_init_timeouts function allows you to initialize the
+pretimeout and timeout fields using the module pretimeout and timeout
+parameter or by retrieving the elements in the timeout-sec property from
+the device tree (if the module pretimeout and timeout parameter are
+invalid). Best practice is to set the default pretimeout and timeout
+values as pretimeout and timeout values in the watchdog_device and then
+use this function to set the user preferred pretimeout and timeout value.
 This routine returns zero on success and a negative errno code for failure.
diff --git a/drivers/watchdog/watchdog_core.c b/drivers/watchdog/watchdog_core.c
index 1a80594..44918d5 100644
--- a/drivers/watchdog/watchdog_core.c
+++ b/drivers/watchdog/watchdog_core.c
@@ -85,57 +85,126 @@ static void watchdog_deferred_registration_del(struct watchdog_device *wdd)
 static void watchdog_check_min_max_timeout(struct watchdog_device *wdd)
 {
 	/*
-	 * Check that we have valid min and max timeout values, if
-	 * not reset them both to 0 (=not used or unknown)
+	 * Check that we have valid min and max pretimeout and timeout values,
+	 * if not, reset them all to 0 (=not used or unknown)
 	 */
-	if (wdd->min_timeout > wdd->max_timeout) {
-		pr_info("Invalid min and max timeout values, resetting to 0!\n");
+	if (wdd->min_pretimeout > wdd->max_pretimeout ||
+	    wdd->min_timeout > wdd->max_timeout ||
+	    wdd->min_timeout < wdd->min_pretimeout ||
+	    wdd->max_timeout < wdd->max_pretimeout) {
+		pr_info("Invalid min or max timeouts, resetting to 0\n");
+		wdd->min_pretimeout = 0;
+		wdd->max_pretimeout = 0;
 		wdd->min_timeout = 0;
 		wdd->max_timeout = 0;
 	}
 }
 
 /**
- * watchdog_init_timeout() - initialize the timeout field
+ * watchdog_init_timeouts() - initialize the pretimeout and timeout field
+ * @pretimeout_parm: pretimeout module parameter
  * @timeout_parm: timeout module parameter
  * @dev: Device that stores the timeout-sec property
  *
- * Initialize the timeout field of the watchdog_device struct with either the
- * timeout module parameter (if it is valid value) or the timeout-sec property
- * (only if it is a valid value and the timeout_parm is out of bounds).
- * If none of them are valid then we keep the old value (which should normally
- * be the default timeout value.
+ * Initialize the pretimeout and timeout field of the watchdog_device struct
+ * with both the pretimeout and timeout module parameters (if they are valid) or
+ * the timeout-sec property (only if they are valid and the pretimeout_parm or
+ * timeout_parm is out of bounds). If one of them is invalid, then we keep
+ * the old value (which should normally be the default timeout value).
  *
  * A zero is returned on success and -EINVAL for failure.
  */
-int watchdog_init_timeout(struct watchdog_device *wdd,
-				unsigned int timeout_parm, struct device *dev)
+int watchdog_init_timeouts(struct watchdog_device *wdd,
+			   unsigned int pretimeout_parm,
+			   unsigned int timeout_parm,
+			   struct device *dev)
 {
-	unsigned int t = 0;
-	int ret = 0;
+	int ret = 0, length = 0;
+	u32 timeouts[2] = {0};
+	struct property *prop;
 
 	watchdog_check_min_max_timeout(wdd);
 
-	/* try to get the timeout module parameter first */
-	if (!watchdog_timeout_invalid(wdd, timeout_parm) && timeout_parm) {
-		wdd->timeout = timeout_parm;
-		return ret;
-	}
-	if (timeout_parm)
+	/*
+	 * Backup the timeouts of wdd, and set them to the parameters,
+	 * because watchdog_pretimeout_invalid uses wdd->timeout to validate
+	 * the pretimeout_parm, and watchdog_timeout_invalid uses
+	 * wdd->pretimeout to validate timeout_parm.
+	 * if any of parameters is wrong, restore the default values before
+	 * return.
+	 */
+	timeouts[0] = wdd->timeout;
+	timeouts[1] = wdd->pretimeout;
+	wdd->timeout = timeout_parm;
+	wdd->pretimeout = pretimeout_parm;
+
+	/*
+	 * Try to get the pretimeout module parameter first.
+	 * Note: zero is a valid value for pretimeout.
+	 */
+	if (watchdog_pretimeout_invalid(wdd, pretimeout_parm))
 		ret = -EINVAL;
 
-	/* try to get the timeout_sec property */
-	if (dev == NULL || dev->of_node == NULL)
-		return ret;
-	of_property_read_u32(dev->of_node, "timeout-sec", &t);
-	if (!watchdog_timeout_invalid(wdd, t) && t)
-		wdd->timeout = t;
-	else
+	/*
+	 * Try to get the timeout module parameter,
+	 * if it's valid and pretimeout is valid(ret == 0),
+	 * assignment and return zero. Otherwise, try dtb.
+	 */
+	if (timeout_parm && !ret) {
+		if (!watchdog_timeout_invalid(wdd, timeout_parm))
+			return 0;
 		ret = -EINVAL;
+	}
 
-	return ret;
+	/*
+	 * Either at least one of the module parameters is invalid,
+	 * or timeout_parm is 0. Try to get the timeout_sec property.
+	 */
+	if (!dev || !dev->of_node) {
+		wdd->timeout = timeouts[0];
+		wdd->pretimeout = timeouts[1];
+		return ret;
+	}
+
+	/*
+	 * Backup default values to *_parms,
+	 * timeouts[] will be used by of_property_read_u32_array.
+	 */
+	timeout_parm = timeouts[0];
+	pretimeout_parm = timeouts[1];
+
+	prop = of_find_property(dev->of_node, "timeout-sec", &length);
+	if (prop && length > 0 && length <= sizeof(u32) * 2) {
+		of_property_read_u32_array(dev->of_node,
+					   "timeout-sec", timeouts,
+					   length / sizeof(u32));
+		wdd->timeout = timeouts[0];
+		wdd->pretimeout = timeouts[1];
+
+		if (length == sizeof(u32) * 2) {
+			if (watchdog_pretimeout_invalid(wdd, timeouts[1]))
+				goto error;
+			ret = 0;
+		} else {
+			ret = -EINVAL;
+		}
+
+		if (!watchdog_timeout_invalid(wdd, timeouts[0]) &&
+		    timeouts[0]) {
+			if (ret) /* Only one value in "timeout-sec" */
+				wdd->pretimeout = pretimeout_parm;
+			return 0;
+		}
+	}
+
+error:
+	/* restore default values */
+	wdd->timeout = timeout_parm;
+	wdd->pretimeout = pretimeout_parm;
+
+	return -EINVAL;
 }
-EXPORT_SYMBOL_GPL(watchdog_init_timeout);
+EXPORT_SYMBOL_GPL(watchdog_init_timeouts);
 
 static int __watchdog_register_device(struct watchdog_device *wdd)
 {
diff --git a/drivers/watchdog/watchdog_dev.c b/drivers/watchdog/watchdog_dev.c
index 6aaefba..af0777e 100644
--- a/drivers/watchdog/watchdog_dev.c
+++ b/drivers/watchdog/watchdog_dev.c
@@ -218,6 +218,38 @@ out_timeout:
 }
 
 /*
+ *	watchdog_set_pretimeout: set the watchdog timer pretimeout
+ *	@wddev: the watchdog device to set the timeout for
+ *	@pretimeout: pretimeout to set in seconds
+ */
+
+static int watchdog_set_pretimeout(struct watchdog_device *wddev,
+				   unsigned int pretimeout)
+{
+	int err;
+
+	if (!wddev->ops->set_pretimeout ||
+	    !(wddev->info->options & WDIOF_PRETIMEOUT))
+		return -EOPNOTSUPP;
+
+	if (watchdog_pretimeout_invalid(wddev, pretimeout))
+		return -EINVAL;
+
+	mutex_lock(&wddev->lock);
+
+	if (test_bit(WDOG_UNREGISTERED, &wddev->status)) {
+		err = -ENODEV;
+		goto out_pretimeout;
+	}
+
+	err = wddev->ops->set_pretimeout(wddev, pretimeout);
+
+out_pretimeout:
+	mutex_unlock(&wddev->lock);
+	return err;
+}
+
+/*
  *	watchdog_get_timeleft: wrapper to get the time left before a reboot
  *	@wddev: the watchdog device to get the remaining time from
  *	@timeleft: the time that's left
@@ -388,6 +420,27 @@ static long watchdog_ioctl(struct file *file, unsigned int cmd,
 		if (wdd->timeout == 0)
 			return -EOPNOTSUPP;
 		return put_user(wdd->timeout, p);
+	case WDIOC_SETPRETIMEOUT:
+		/* check if we support the pretimeout */
+		if (!(wdd->info->options & WDIOF_PRETIMEOUT))
+			return -EOPNOTSUPP;
+		if (get_user(val, p))
+			return -EFAULT;
+		err = watchdog_set_pretimeout(wdd, val);
+		if (err < 0)
+			return err;
+		/*
+		 * If the watchdog is active then we send a keepalive ping
+		 * to make sure that the watchdog keeps running (and if
+		 * possible that it takes the new pretimeout)
+		 */
+		watchdog_ping(wdd);
+		/* Fall */
+	case WDIOC_GETPRETIMEOUT:
+		/* check if we support the pretimeout */
+		if (wdd->info->options & WDIOF_PRETIMEOUT)
+			return put_user(wdd->pretimeout, p);
+		return -EOPNOTSUPP;
 	case WDIOC_GETTIMELEFT:
 		err = watchdog_get_timeleft(wdd, &val);
 		if (err)
diff --git a/include/linux/watchdog.h b/include/linux/watchdog.h
index d74a0e9..eaea7b0 100644
--- a/include/linux/watchdog.h
+++ b/include/linux/watchdog.h
@@ -25,6 +25,7 @@ struct watchdog_device;
  * @ping:	The routine that sends a keepalive ping to the watchdog device.
  * @status:	The routine that shows the status of the watchdog device.
  * @set_timeout:The routine for setting the watchdog devices timeout value.
+ * @set_pretimeout:The routine for setting the watchdog devices pretimeout value
  * @get_timeleft:The routine that get's the time that's left before a reset.
  * @ref:	The ref operation for dyn. allocated watchdog_device structs
  * @unref:	The unref operation for dyn. allocated watchdog_device structs
@@ -44,6 +45,7 @@ struct watchdog_ops {
 	int (*ping)(struct watchdog_device *);
 	unsigned int (*status)(struct watchdog_device *);
 	int (*set_timeout)(struct watchdog_device *, unsigned int);
+	int (*set_pretimeout)(struct watchdog_device *, unsigned int);
 	unsigned int (*get_timeleft)(struct watchdog_device *);
 	void (*ref)(struct watchdog_device *);
 	void (*unref)(struct watchdog_device *);
@@ -62,6 +64,9 @@ struct watchdog_ops {
  * @timeout:	The watchdog devices timeout value.
  * @min_timeout:The watchdog devices minimum timeout value.
  * @max_timeout:The watchdog devices maximum timeout value.
+ * @pretimeout:	The watchdog devices pretimeout value.
+ * @min_pretimeout:The watchdog devices minimum pretimeout value.
+ * @max_pretimeout:The watchdog devices maximum pretimeout value.
  * @driver-data:Pointer to the drivers private data.
  * @lock:	Lock for watchdog core internal use only.
  * @status:	Field that contains the devices internal status bits.
@@ -88,6 +93,9 @@ struct watchdog_device {
 	unsigned int timeout;
 	unsigned int min_timeout;
 	unsigned int max_timeout;
+	unsigned int pretimeout;
+	unsigned int min_pretimeout;
+	unsigned int max_pretimeout;
 	void *driver_data;
 	struct mutex lock;
 	unsigned long status;
@@ -119,8 +127,22 @@ static inline void watchdog_set_nowayout(struct watchdog_device *wdd, bool noway
 /* Use the following function to check if a timeout value is invalid */
 static inline bool watchdog_timeout_invalid(struct watchdog_device *wdd, unsigned int t)
 {
-	return ((wdd->max_timeout != 0) &&
-		(t < wdd->min_timeout || t > wdd->max_timeout));
+	return (wdd->max_timeout &&
+		(t < wdd->min_timeout || t > wdd->max_timeout)) ||
+	       (wdd->pretimeout && t <= wdd->pretimeout);
+}
+
+/*
+ * Use the following function to check if a pretimeout value is invalid.
+ * It can be "0", that means we don't use pretimeout.
+ * This function returns false, when pretimeout is 0.
+ */
+static inline bool watchdog_pretimeout_invalid(struct watchdog_device *wdd,
+					       unsigned int t)
+{
+	return t && ((wdd->max_pretimeout &&
+		      (t < wdd->min_pretimeout || t > wdd->max_pretimeout)) ||
+		     (wdd->timeout && t >= wdd->timeout));
 }
 
 /* Use the following functions to manipulate watchdog driver specific data */
@@ -135,8 +157,17 @@ static inline void *watchdog_get_drvdata(struct watchdog_device *wdd)
 }
 
 /* drivers/watchdog/watchdog_core.c */
-extern int watchdog_init_timeout(struct watchdog_device *wdd,
-				  unsigned int timeout_parm, struct device *dev);
+int watchdog_init_timeouts(struct watchdog_device *wdd,
+			   unsigned int pretimeout_parm,
+			   unsigned int timeout_parm,
+			   struct device *dev);
+static inline int watchdog_init_timeout(struct watchdog_device *wdd,
+					unsigned int timeout_parm,
+					struct device *dev)
+{
+	return watchdog_init_timeouts(wdd, 0, timeout_parm, dev);
+}
+
 extern int watchdog_register_device(struct watchdog_device *);
 extern void watchdog_unregister_device(struct watchdog_device *);
 
-- 
2.5.0

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[PATCH v9 5/5] Watchdog: introduce ARM SBSA watchdog driver

[fu.wei]

From: Fu Wei <fu.wei@linaro.org>

This driver bases on linux kernel watchdog framework, and
use "pretimeout" in the framework. It supports getting timeout and
pretimeout from parameter and FDT at the driver init stage.
In first timeout, the interrupt routine run panic to save
system context.

Signed-off-by: Fu Wei <fu.wei@linaro.org>
Tested-by: Pratyush Anand <panand@redhat.com>
---
 drivers/watchdog/Kconfig     |  14 ++
 drivers/watchdog/Makefile    |   1 +
 drivers/watchdog/sbsa_gwdt.c | 459 +++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 474 insertions(+)

diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
index 79e1aa1..5cc8455 100644
--- a/drivers/watchdog/Kconfig
+++ b/drivers/watchdog/Kconfig
@@ -173,6 +173,20 @@ 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. This watchdog has two Watchdog timeouts.
+	  The first timeout will trigger a panic; the second timeout will
+	  trigger a system reset.
+	  More details: ARM DEN0029B - Server Base System Architecture (SBSA)
+
+	  To compile this driver as module, choose M here: The module
+	  will be called sbsa_gwdt.
+
 config AT91RM9200_WATCHDOG
 	tristate "AT91RM9200 watchdog"
 	depends on SOC_AT91RM9200 && MFD_SYSCON
diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
index 0c616e3..b74a3ea 100644
--- a/drivers/watchdog/Makefile
+++ b/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-$(CONFIG_AT91RM9200_WATCHDOG) += at91rm9200_wdt.o
 obj-$(CONFIG_AT91SAM9X_WATCHDOG) += at91sam9_wdt.o
 obj-$(CONFIG_CADENCE_WATCHDOG) += cadence_wdt.o
diff --git a/drivers/watchdog/sbsa_gwdt.c b/drivers/watchdog/sbsa_gwdt.c
new file mode 100644
index 0000000..6fd1c63
--- /dev/null
+++ b/drivers/watchdog/sbsa_gwdt.c
@@ -0,0 +1,459 @@
+/*
+ * 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>
+ *
+ * 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.
+ *
+ * The SBSA Generic watchdog driver is compatible with the pretimeout
+ * concept of Linux kernel.
+ * The timeout and pretimeout are determined by WCV or WOR.
+ * The first watch period is set by writing WCV directly, that can
+ * support more than 10s timeout at the maximum system counter
+ * frequency (400MHz).
+ * When WS0 is triggered, the second watch period (pretimeout) is
+ * determined by one of these registers:
+ * (1)WOR: 32bit register, this gives a maximum watch period of
+ * around 10s at the maximum system counter frequency. It's loaded
+ * automatically by hardware.
+ * (2)WCV: If the pretimeout value is greater then "max_wor_timeout",
+ * it will be loaded in WS0 interrupt routine. If system is in
+ * ws0_mode (reboot with watchdog enabled and WS0 == true), the ping
+ * operation will only reload WCV.
+ * More details about the hardware specification of this device:
+ * ARM DEN0029B - Server Base System Architecture (SBSA)
+ *
+ * Kernel/API:                         P------------------| pretimeout
+ *               |----------------------------------------T timeout
+ * SBSA GWDT:                          P---WOR (or WCV)---WS1 pretimeout
+ *               |-------WCV----------WS0~~~(ws0_mode)~~~~T timeout
+ */
+
+#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>
+
+/* 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_LO			0x010
+#define SBSA_GWDT_WCV_HI			0x014
+
+/* 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.
+ * @ws0_mode:		indicate the system boot in the second stage timeout.
+ * @max_wor_timeout:	the maximum timeout value for WOR (in seconds).
+ * @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;
+	bool			ws0_mode;
+	int			max_wor_timeout;
+	void __iomem		*refresh_base;
+	void __iomem		*control_base;
+};
+
+#define to_sbsa_gwdt(e) container_of(e, struct sbsa_gwdt, wdd)
+
+#define DEFAULT_TIMEOUT		60 /* seconds, the 1st + 2nd watch periods*/
+#define DEFAULT_PRETIMEOUT	30 /* seconds, the 2nd watch period*/
+
+static unsigned int timeout;
+module_param(timeout, uint, 0);
+MODULE_PARM_DESC(timeout,
+		 "Watchdog timeout in seconds. (>=0, default="
+		 __MODULE_STRING(DEFAULT_TIMEOUT) ")");
+
+static unsigned int pretimeout;
+module_param(pretimeout, uint, 0);
+MODULE_PARM_DESC(pretimeout,
+		 "Watchdog pretimeout in seconds. (>=0, default="
+		 __MODULE_STRING(DEFAULT_PRETIMEOUT) ")");
+
+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) ")");
+
+/*
+ * help functions for accessing 64bit WCV register
+ */
+static u64 sbsa_gwdt_get_wcv(struct watchdog_device *wdd)
+{
+	u32 wcv_lo, wcv_hi;
+	struct sbsa_gwdt *gwdt = to_sbsa_gwdt(wdd);
+
+	do {
+		wcv_hi = readl_relaxed(gwdt->control_base + SBSA_GWDT_WCV_HI);
+		wcv_lo = readl_relaxed(gwdt->control_base + SBSA_GWDT_WCV_LO);
+	} while (wcv_hi != readl_relaxed(gwdt->control_base +
+					 SBSA_GWDT_WCV_HI));
+
+	return (((u64)wcv_hi << 32) | wcv_lo);
+}
+
+static void sbsa_gwdt_set_wcv(struct watchdog_device *wdd, unsigned int t)
+{
+	struct sbsa_gwdt *gwdt = to_sbsa_gwdt(wdd);
+	u64 wcv;
+
+	wcv = arch_counter_get_cntvct() + (u64)t * gwdt->clk;
+
+	writel_relaxed(upper_32_bits(wcv),
+		       gwdt->control_base + SBSA_GWDT_WCV_HI);
+	writel_relaxed(lower_32_bits(wcv),
+		       gwdt->control_base + SBSA_GWDT_WCV_LO);
+}
+
+/*
+ * inline functions for reloading 64bit WCV register
+ */
+static inline void reload_pretimeout_to_wcv(struct watchdog_device *wdd)
+{
+	sbsa_gwdt_set_wcv(wdd, wdd->pretimeout);
+}
+
+static inline void reload_first_stage_to_wcv(struct watchdog_device *wdd)
+{
+	sbsa_gwdt_set_wcv(wdd, wdd->timeout - wdd->pretimeout);
+}
+
+/*
+ * watchdog operation functions
+ */
+static int sbsa_gwdt_set_timeout(struct watchdog_device *wdd,
+				 unsigned int timeout)
+{
+	wdd->timeout = timeout;
+
+	return 0;
+}
+
+static int sbsa_gwdt_set_pretimeout(struct watchdog_device *wdd,
+				    unsigned int pretimeout)
+{
+	struct sbsa_gwdt *gwdt = to_sbsa_gwdt(wdd);
+	u32 wor;
+
+	wdd->pretimeout = pretimeout;
+
+	/* If ws0_mode == true, we won't touch WOR */
+	if (!gwdt->ws0_mode) {
+		if (!pretimeout)
+			/*
+			 * If pretimeout is 0, it gives driver a timeslot (1s)
+			 * to update WCV after an explicit refresh
+			 * (sbsa_gwdt_start)
+			 */
+			wor = gwdt->clk;
+		else
+			if (pretimeout > gwdt->max_wor_timeout)
+				wor = U32_MAX;
+			else
+				wor = pretimeout * gwdt->clk;
+
+		/* wtite WOR, that will cause an explicit watchdog refresh */
+		writel_relaxed(wor, gwdt->control_base + SBSA_GWDT_WOR);
+	}
+
+	return 0;
+}
+
+static unsigned int sbsa_gwdt_get_timeleft(struct watchdog_device *wdd)
+{
+	struct sbsa_gwdt *gwdt = to_sbsa_gwdt(wdd);
+	u64 timeleft = sbsa_gwdt_get_wcv(wdd) - arch_counter_get_cntvct();
+
+	do_div(timeleft, gwdt->clk);
+
+	return timeleft;
+}
+
+static int sbsa_gwdt_keepalive(struct watchdog_device *wdd)
+{
+	struct sbsa_gwdt *gwdt = to_sbsa_gwdt(wdd);
+
+	if (gwdt->ws0_mode)
+		reload_pretimeout_to_wcv(wdd);
+	else
+		reload_first_stage_to_wcv(wdd);
+
+	return 0;
+}
+
+static int sbsa_gwdt_start(struct watchdog_device *wdd)
+{
+	struct sbsa_gwdt *gwdt = to_sbsa_gwdt(wdd);
+
+	/* If ws0_mode == true, the watchdog is enabled */
+	if (!gwdt->ws0_mode)
+		/* writing WCS will cause an explicit watchdog refresh */
+		writel_relaxed(SBSA_GWDT_WCS_EN,
+			       gwdt->control_base + SBSA_GWDT_WCS);
+
+	return sbsa_gwdt_keepalive(wdd);
+}
+
+static int sbsa_gwdt_stop(struct watchdog_device *wdd)
+{
+	struct sbsa_gwdt *gwdt = to_sbsa_gwdt(wdd);
+
+	writel_relaxed(0, gwdt->control_base + SBSA_GWDT_WCS);
+	/*
+	 * Writing WCS has caused an explicit watchdog refresh.
+	 * Both watchdog signals are deasserted, so clean ws0_mode flag.
+	 */
+	gwdt->ws0_mode = false;
+
+	return 0;
+}
+
+static irqreturn_t sbsa_gwdt_interrupt(int irq, void *dev_id)
+{
+	struct sbsa_gwdt *gwdt = (struct sbsa_gwdt *)dev_id;
+	struct watchdog_device *wdd = &gwdt->wdd;
+
+	/* We don't use pretimeout, trigger WS1 now */
+	if (!wdd->pretimeout)
+		sbsa_gwdt_set_wcv(wdd, 0);
+
+	/*
+	 * The pretimeout is valid, go panic
+	 * If pretimeout is greater then "max_wor_timeout",
+	 * reload the right value to WCV, then panic
+	 */
+	if (wdd->pretimeout > gwdt->max_wor_timeout)
+		reload_pretimeout_to_wcv(wdd);
+	panic("SBSA Watchdog pre-timeout");
+
+	return IRQ_HANDLED;
+}
+
+static struct watchdog_info sbsa_gwdt_info = {
+	.identity	= "SBSA Generic Watchdog",
+	.options	= WDIOF_SETTIMEOUT |
+			  WDIOF_KEEPALIVEPING |
+			  WDIOF_MAGICCLOSE |
+			  WDIOF_PRETIMEOUT |
+			  WDIOF_CARDRESET,
+};
+
+static struct watchdog_ops sbsa_gwdt_ops = {
+	.owner		= THIS_MODULE,
+	.start		= sbsa_gwdt_start,
+	.stop		= sbsa_gwdt_stop,
+	.ping		= sbsa_gwdt_keepalive,
+	.set_timeout	= sbsa_gwdt_set_timeout,
+	.set_pretimeout	= sbsa_gwdt_set_pretimeout,
+	.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);
+
+	irq = platform_get_irq(pdev, 0);
+	if (irq < 0) {
+		dev_err(dev, "unable to get ws0 interrupt.\n");
+		return irq;
+	}
+
+	/*
+	 * 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;
+	gwdt->max_wor_timeout = U32_MAX / gwdt->clk;
+	gwdt->ws0_mode = false;
+
+	wdd = &gwdt->wdd;
+	wdd->parent = dev;
+	wdd->info = &sbsa_gwdt_info;
+	wdd->ops = &sbsa_gwdt_ops;
+	watchdog_set_drvdata(wdd, gwdt);
+	watchdog_set_nowayout(wdd, nowayout);
+
+	wdd->min_pretimeout = 0;
+	wdd->min_timeout = 1;
+
+	/*
+	 * Because the maximum of gwdt->clk is 400MHz and the maximum of WCV is
+	 * U64_MAX, so the result of (U64_MAX / gwdt->clk) is always greater
+	 * than U32_MAX. And the maximum of "unsigned int" is U32_MAX on ARM64.
+	 * So we set the maximum value of pretimeout and timeout below.
+	 */
+	wdd->max_pretimeout = U32_MAX - 1;
+	wdd->max_timeout = U32_MAX;
+
+	wdd->pretimeout = DEFAULT_PRETIMEOUT;
+	wdd->timeout = DEFAULT_TIMEOUT;
+	watchdog_init_timeouts(wdd, pretimeout, timeout, dev);
+
+	status = readl_relaxed(gwdt->control_base + SBSA_GWDT_WCS);
+	if (status & SBSA_GWDT_WCS_WS1) {
+		dev_warn(dev, "System reset by WDT.\n");
+		wdd->bootstatus |= WDIOF_CARDRESET;
+	} else if (status == (SBSA_GWDT_WCS_WS0 | SBSA_GWDT_WCS_EN)) {
+		gwdt->ws0_mode = true;
+	}
+
+	ret = devm_request_irq(dev, irq, sbsa_gwdt_interrupt, 0,
+			       pdev->name, gwdt);
+	if (ret) {
+		dev_err(dev, "unable to request IRQ %d\n", irq);
+		return ret;
+	}
+
+	ret = watchdog_register_device(wdd);
+	if (ret)
+		return ret;
+
+	/* If ws0_mode == true, the line won't update WOR */
+	sbsa_gwdt_set_pretimeout(wdd, wdd->pretimeout);
+
+	/*
+	 * If watchdog is already enabled, do a ping operation
+	 * to keep system running
+	 */
+	if (status & SBSA_GWDT_WCS_EN)
+		sbsa_gwdt_keepalive(wdd);
+
+	dev_info(dev, "Initialized with %ds timeout, %ds pretimeout @ %u Hz%s\n",
+		 wdd->timeout, wdd->pretimeout, gwdt->clk,
+		 status & SBSA_GWDT_WCS_EN ?
+			gwdt->ws0_mode ? " [second stage]" : " [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 and configure it 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 = "sbsa-gwdt", },
+	{},
+};
+MODULE_DEVICE_TABLE(platform, sbsa_gwdt_pdev_match);
+
+static struct platform_driver sbsa_gwdt_driver = {
+	.driver = {
+		.name = "sbsa-gwdt",
+		.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_LICENSE("GPL v2");
-- 
2.5.0

Re: [Linaro-acpi] [PATCH v9 5/5] Watchdog: introduce ARM SBSA watchdog driver

[Graeme Gregory]

Hi Fu Wei,

Looks ok to me.

Reviewed by: Graeme Gregory <graeme.gregory@linaro.org>

Thanks

On Mon, Nov 09, 2015 at 03:31:19PM +0800, fu.wei@linaro.org wrote:
> From: Fu Wei <fu.wei@linaro.org>
> 
> This driver bases on linux kernel watchdog framework, and
> use "pretimeout" in the framework. It supports getting timeout and
> pretimeout from parameter and FDT at the driver init stage.
> In first timeout, the interrupt routine run panic to save
> system context.
> 
> Signed-off-by: Fu Wei <fu.wei@linaro.org>
> Tested-by: Pratyush Anand <panand@redhat.com>
> ---
>  drivers/watchdog/Kconfig     |  14 ++
>  drivers/watchdog/Makefile    |   1 +
>  drivers/watchdog/sbsa_gwdt.c | 459 +++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 474 insertions(+)
> 
> diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
> index 79e1aa1..5cc8455 100644
> --- a/drivers/watchdog/Kconfig
> +++ b/drivers/watchdog/Kconfig
> @@ -173,6 +173,20 @@ 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. This watchdog has two Watchdog timeouts.
> +	  The first timeout will trigger a panic; the second timeout will
> +	  trigger a system reset.
> +	  More details: ARM DEN0029B - Server Base System Architecture (SBSA)
> +
> +	  To compile this driver as module, choose M here: The module
> +	  will be called sbsa_gwdt.
> +
>  config AT91RM9200_WATCHDOG
>  	tristate "AT91RM9200 watchdog"
>  	depends on SOC_AT91RM9200 && MFD_SYSCON
> diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
> index 0c616e3..b74a3ea 100644
> --- a/drivers/watchdog/Makefile
> +++ b/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_AT91RM9200_WATCHDOG) += at91rm9200_wdt.o
>  obj-$(CONFIG_AT91SAM9X_WATCHDOG) += at91sam9_wdt.o
>  obj-$(CONFIG_CADENCE_WATCHDOG) += cadence_wdt.o
> diff --git a/drivers/watchdog/sbsa_gwdt.c b/drivers/watchdog/sbsa_gwdt.c
> new file mode 100644
> index 0000000..6fd1c63
> --- /dev/null
> +++ b/drivers/watchdog/sbsa_gwdt.c
> @@ -0,0 +1,459 @@
> +/*
> + * 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>
> + *
> + * 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.
> + *
> + * The SBSA Generic watchdog driver is compatible with the pretimeout
> + * concept of Linux kernel.
> + * The timeout and pretimeout are determined by WCV or WOR.
> + * The first watch period is set by writing WCV directly, that can
> + * support more than 10s timeout at the maximum system counter
> + * frequency (400MHz).
> + * When WS0 is triggered, the second watch period (pretimeout) is
> + * determined by one of these registers:
> + * (1)WOR: 32bit register, this gives a maximum watch period of
> + * around 10s at the maximum system counter frequency. It's loaded
> + * automatically by hardware.
> + * (2)WCV: If the pretimeout value is greater then "max_wor_timeout",
> + * it will be loaded in WS0 interrupt routine. If system is in
> + * ws0_mode (reboot with watchdog enabled and WS0 == true), the ping
> + * operation will only reload WCV.
> + * More details about the hardware specification of this device:
> + * ARM DEN0029B - Server Base System Architecture (SBSA)
> + *
> + * Kernel/API:                         P------------------| pretimeout
> + *               |----------------------------------------T timeout
> + * SBSA GWDT:                          P---WOR (or WCV)---WS1 pretimeout
> + *               |-------WCV----------WS0~~~(ws0_mode)~~~~T timeout
> + */
> +
> +#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>
> +
> +/* 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_LO			0x010
> +#define SBSA_GWDT_WCV_HI			0x014
> +
> +/* 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.
> + * @ws0_mode:		indicate the system boot in the second stage timeout.
> + * @max_wor_timeout:	the maximum timeout value for WOR (in seconds).
> + * @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;
> +	bool			ws0_mode;
> +	int			max_wor_timeout;
> +	void __iomem		*refresh_base;
> +	void __iomem		*control_base;
> +};
> +
> +#define to_sbsa_gwdt(e) container_of(e, struct sbsa_gwdt, wdd)
> +
> +#define DEFAULT_TIMEOUT		60 /* seconds, the 1st + 2nd watch periods*/
> +#define DEFAULT_PRETIMEOUT	30 /* seconds, the 2nd watch period*/
> +
> +static unsigned int timeout;
> +module_param(timeout, uint, 0);
> +MODULE_PARM_DESC(timeout,
> +		 "Watchdog timeout in seconds. (>=0, default="
> +		 __MODULE_STRING(DEFAULT_TIMEOUT) ")");
> +
> +static unsigned int pretimeout;
> +module_param(pretimeout, uint, 0);
> +MODULE_PARM_DESC(pretimeout,
> +		 "Watchdog pretimeout in seconds. (>=0, default="
> +		 __MODULE_STRING(DEFAULT_PRETIMEOUT) ")");
> +
> +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) ")");
> +
> +/*
> + * help functions for accessing 64bit WCV register
> + */
> +static u64 sbsa_gwdt_get_wcv(struct watchdog_device *wdd)
> +{
> +	u32 wcv_lo, wcv_hi;
> +	struct sbsa_gwdt *gwdt = to_sbsa_gwdt(wdd);
> +
> +	do {
> +		wcv_hi = readl_relaxed(gwdt->control_base + SBSA_GWDT_WCV_HI);
> +		wcv_lo = readl_relaxed(gwdt->control_base + SBSA_GWDT_WCV_LO);
> +	} while (wcv_hi != readl_relaxed(gwdt->control_base +
> +					 SBSA_GWDT_WCV_HI));
> +
> +	return (((u64)wcv_hi << 32) | wcv_lo);
> +}
> +
> +static void sbsa_gwdt_set_wcv(struct watchdog_device *wdd, unsigned int t)
> +{
> +	struct sbsa_gwdt *gwdt = to_sbsa_gwdt(wdd);
> +	u64 wcv;
> +
> +	wcv = arch_counter_get_cntvct() + (u64)t * gwdt->clk;
> +
> +	writel_relaxed(upper_32_bits(wcv),
> +		       gwdt->control_base + SBSA_GWDT_WCV_HI);
> +	writel_relaxed(lower_32_bits(wcv),
> +		       gwdt->control_base + SBSA_GWDT_WCV_LO);
> +}
> +
> +/*
> + * inline functions for reloading 64bit WCV register
> + */
> +static inline void reload_pretimeout_to_wcv(struct watchdog_device *wdd)
> +{
> +	sbsa_gwdt_set_wcv(wdd, wdd->pretimeout);
> +}
> +
> +static inline void reload_first_stage_to_wcv(struct watchdog_device *wdd)
> +{
> +	sbsa_gwdt_set_wcv(wdd, wdd->timeout - wdd->pretimeout);
> +}
> +
> +/*
> + * watchdog operation functions
> + */
> +static int sbsa_gwdt_set_timeout(struct watchdog_device *wdd,
> +				 unsigned int timeout)
> +{
> +	wdd->timeout = timeout;
> +
> +	return 0;
> +}
> +
> +static int sbsa_gwdt_set_pretimeout(struct watchdog_device *wdd,
> +				    unsigned int pretimeout)
> +{
> +	struct sbsa_gwdt *gwdt = to_sbsa_gwdt(wdd);
> +	u32 wor;
> +
> +	wdd->pretimeout = pretimeout;
> +
> +	/* If ws0_mode == true, we won't touch WOR */
> +	if (!gwdt->ws0_mode) {
> +		if (!pretimeout)
> +			/*
> +			 * If pretimeout is 0, it gives driver a timeslot (1s)
> +			 * to update WCV after an explicit refresh
> +			 * (sbsa_gwdt_start)
> +			 */
> +			wor = gwdt->clk;
> +		else
> +			if (pretimeout > gwdt->max_wor_timeout)
> +				wor = U32_MAX;
> +			else
> +				wor = pretimeout * gwdt->clk;
> +
> +		/* wtite WOR, that will cause an explicit watchdog refresh */
> +		writel_relaxed(wor, gwdt->control_base + SBSA_GWDT_WOR);
> +	}
> +
> +	return 0;
> +}
> +
> +static unsigned int sbsa_gwdt_get_timeleft(struct watchdog_device *wdd)
> +{
> +	struct sbsa_gwdt *gwdt = to_sbsa_gwdt(wdd);
> +	u64 timeleft = sbsa_gwdt_get_wcv(wdd) - arch_counter_get_cntvct();
> +
> +	do_div(timeleft, gwdt->clk);
> +
> +	return timeleft;
> +}
> +
> +static int sbsa_gwdt_keepalive(struct watchdog_device *wdd)
> +{
> +	struct sbsa_gwdt *gwdt = to_sbsa_gwdt(wdd);
> +
> +	if (gwdt->ws0_mode)
> +		reload_pretimeout_to_wcv(wdd);
> +	else
> +		reload_first_stage_to_wcv(wdd);
> +
> +	return 0;
> +}
> +
> +static int sbsa_gwdt_start(struct watchdog_device *wdd)
> +{
> +	struct sbsa_gwdt *gwdt = to_sbsa_gwdt(wdd);
> +
> +	/* If ws0_mode == true, the watchdog is enabled */
> +	if (!gwdt->ws0_mode)
> +		/* writing WCS will cause an explicit watchdog refresh */
> +		writel_relaxed(SBSA_GWDT_WCS_EN,
> +			       gwdt->control_base + SBSA_GWDT_WCS);
> +
> +	return sbsa_gwdt_keepalive(wdd);
> +}
> +
> +static int sbsa_gwdt_stop(struct watchdog_device *wdd)
> +{
> +	struct sbsa_gwdt *gwdt = to_sbsa_gwdt(wdd);
> +
> +	writel_relaxed(0, gwdt->control_base + SBSA_GWDT_WCS);
> +	/*
> +	 * Writing WCS has caused an explicit watchdog refresh.
> +	 * Both watchdog signals are deasserted, so clean ws0_mode flag.
> +	 */
> +	gwdt->ws0_mode = false;
> +
> +	return 0;
> +}
> +
> +static irqreturn_t sbsa_gwdt_interrupt(int irq, void *dev_id)
> +{
> +	struct sbsa_gwdt *gwdt = (struct sbsa_gwdt *)dev_id;
> +	struct watchdog_device *wdd = &gwdt->wdd;
> +
> +	/* We don't use pretimeout, trigger WS1 now */
> +	if (!wdd->pretimeout)
> +		sbsa_gwdt_set_wcv(wdd, 0);
> +
> +	/*
> +	 * The pretimeout is valid, go panic
> +	 * If pretimeout is greater then "max_wor_timeout",
> +	 * reload the right value to WCV, then panic
> +	 */
> +	if (wdd->pretimeout > gwdt->max_wor_timeout)
> +		reload_pretimeout_to_wcv(wdd);
> +	panic("SBSA Watchdog pre-timeout");
> +
> +	return IRQ_HANDLED;
> +}
> +
> +static struct watchdog_info sbsa_gwdt_info = {
> +	.identity	= "SBSA Generic Watchdog",
> +	.options	= WDIOF_SETTIMEOUT |
> +			  WDIOF_KEEPALIVEPING |
> +			  WDIOF_MAGICCLOSE |
> +			  WDIOF_PRETIMEOUT |
> +			  WDIOF_CARDRESET,
> +};
> +
> +static struct watchdog_ops sbsa_gwdt_ops = {
> +	.owner		= THIS_MODULE,
> +	.start		= sbsa_gwdt_start,
> +	.stop		= sbsa_gwdt_stop,
> +	.ping		= sbsa_gwdt_keepalive,
> +	.set_timeout	= sbsa_gwdt_set_timeout,
> +	.set_pretimeout	= sbsa_gwdt_set_pretimeout,
> +	.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);
> +
> +	irq = platform_get_irq(pdev, 0);
> +	if (irq < 0) {
> +		dev_err(dev, "unable to get ws0 interrupt.\n");
> +		return irq;
> +	}
> +
> +	/*
> +	 * 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;
> +	gwdt->max_wor_timeout = U32_MAX / gwdt->clk;
> +	gwdt->ws0_mode = false;
> +
> +	wdd = &gwdt->wdd;
> +	wdd->parent = dev;
> +	wdd->info = &sbsa_gwdt_info;
> +	wdd->ops = &sbsa_gwdt_ops;
> +	watchdog_set_drvdata(wdd, gwdt);
> +	watchdog_set_nowayout(wdd, nowayout);
> +
> +	wdd->min_pretimeout = 0;
> +	wdd->min_timeout = 1;
> +
> +	/*
> +	 * Because the maximum of gwdt->clk is 400MHz and the maximum of WCV is
> +	 * U64_MAX, so the result of (U64_MAX / gwdt->clk) is always greater
> +	 * than U32_MAX. And the maximum of "unsigned int" is U32_MAX on ARM64.
> +	 * So we set the maximum value of pretimeout and timeout below.
> +	 */
> +	wdd->max_pretimeout = U32_MAX - 1;
> +	wdd->max_timeout = U32_MAX;
> +
> +	wdd->pretimeout = DEFAULT_PRETIMEOUT;
> +	wdd->timeout = DEFAULT_TIMEOUT;
> +	watchdog_init_timeouts(wdd, pretimeout, timeout, dev);
> +
> +	status = readl_relaxed(gwdt->control_base + SBSA_GWDT_WCS);
> +	if (status & SBSA_GWDT_WCS_WS1) {
> +		dev_warn(dev, "System reset by WDT.\n");
> +		wdd->bootstatus |= WDIOF_CARDRESET;
> +	} else if (status == (SBSA_GWDT_WCS_WS0 | SBSA_GWDT_WCS_EN)) {
> +		gwdt->ws0_mode = true;
> +	}
> +
> +	ret = devm_request_irq(dev, irq, sbsa_gwdt_interrupt, 0,
> +			       pdev->name, gwdt);
> +	if (ret) {
> +		dev_err(dev, "unable to request IRQ %d\n", irq);
> +		return ret;
> +	}
> +
> +	ret = watchdog_register_device(wdd);
> +	if (ret)
> +		return ret;
> +
> +	/* If ws0_mode == true, the line won't update WOR */
> +	sbsa_gwdt_set_pretimeout(wdd, wdd->pretimeout);
> +
> +	/*
> +	 * If watchdog is already enabled, do a ping operation
> +	 * to keep system running
> +	 */
> +	if (status & SBSA_GWDT_WCS_EN)
> +		sbsa_gwdt_keepalive(wdd);
> +
> +	dev_info(dev, "Initialized with %ds timeout, %ds pretimeout @ %u Hz%s\n",
> +		 wdd->timeout, wdd->pretimeout, gwdt->clk,
> +		 status & SBSA_GWDT_WCS_EN ?
> +			gwdt->ws0_mode ? " [second stage]" : " [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 and configure it 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 = "sbsa-gwdt", },
> +	{},
> +};
> +MODULE_DEVICE_TABLE(platform, sbsa_gwdt_pdev_match);
> +
> +static struct platform_driver sbsa_gwdt_driver = {
> +	.driver = {
> +		.name = "sbsa-gwdt",
> +		.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_LICENSE("GPL v2");
> -- 
> 2.5.0
> 
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> Linaro-acpi@lists.linaro.org
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Re: [PATCH v9 1/5] Documentation: add sbsa-gwdt driver documentation

[Rob Herring]

On Mon, Nov 09, 2015 at 03:31:15PM +0800, fu.wei@linaro.org wrote:
> From: Fu Wei <fu.wei@linaro.org>
> 
> The sbsa-gwdt.txt documentation in devicetree/bindings/watchdog is for
> introducing SBSA(Server Base System Architecture) Generic Watchdog
> device node info into FDT.
> 
> Also add sbsa-gwdt introduction in watchdog-parameters.txt
> 
> Acked-by: Arnd Bergmann <arnd@arndb.de>
> Signed-off-by: Fu Wei <fu.wei@linaro.org>

Acked-by: Rob Herring <robh@kernel.org>

> ---
>  .../devicetree/bindings/watchdog/sbsa-gwdt.txt     | 34 ++++++++++++++++++++++
>  Documentation/watchdog/watchdog-parameters.txt     |  6 ++++
>  2 files changed, 40 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/watchdog/sbsa-gwdt.txt b/Documentation/devicetree/bindings/watchdog/sbsa-gwdt.txt
> new file mode 100644
> index 0000000..2da63db
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/watchdog/sbsa-gwdt.txt
> @@ -0,0 +1,34 @@
> +* 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 and pre-timeout values.
> +  If used, at least first timeout value (in seconds) must be provided.
> +  A second optional value (in seconds) may also be provided and
> +  will be used as the pre-timeout value, if it is given.
> +
> +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 = <60 30>;
> +};
> diff --git a/Documentation/watchdog/watchdog-parameters.txt b/Documentation/watchdog/watchdog-parameters.txt
> index 9f9ec9f..e62c8c4 100644
> --- a/Documentation/watchdog/watchdog-parameters.txt
> +++ b/Documentation/watchdog/watchdog-parameters.txt
> @@ -284,6 +284,12 @@ 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 60s)
> +pretimeout: Watchdog pretimeout in seconds. (default 30s)
> +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
> -- 
> 2.5.0
>