Please find hereafter a new version of the patch with a documentation file and that builds with CONFIG_ACPI unset.
>From a7135e6b4bc7c91d6ac72a4f38157f7f2308615b Mon Sep 17 00:00:00 2001
From: Francois-Nicolas Muller <francois-nicolas.muller@xxxxxxxxx>
Date: Tue, 20 Jan 2015 14:55:42 +0100
Subject: [PATCH] Adding TCO watchdog warning interrupt handling.
This feature is useful to root cause watchdog expiration.
It is activated by boot parameter 'warn_irq' (disabled by default).
Upon first expiration of the TCO watchdog, a warning interrupt is fired, then
the interrupt handler dumps registers and call stack of all available cpus.
TCO watchdog reloads with 2.4 seconds timeout for second expiration.
If CONFIG_ITCO_WARN_PANIC is set, the warning interrupt also calls panic()
which notifies the panic handlers then reboots the platform, depending on
CONFIG_PANIC_TIMEOUT value :
- If CONFIG_PANIC_TIMEOUT is zero or greater than 3 seconds, TCO watchdog will
reset the platform if second expiration happens before TCO has been kicked
again.
- If CONFIG_PANIC_TIMEOUT is < 0, platform will reboot immediately (emergency
restart procedure).
- If CONFIG_PANIC_TIMEOUT is 1 or 2 seconds, platform will reboot after 1 or 2
seconds delay (emergency restart procedure).
See Documentation/watchdog/tco-wdt-warning-interrupt.txt for more details.
Change-Id: I7314a50812529423b117cf28e4a195a356da2f57
Signed-off-by: Francois-Nicolas Muller <francois-nicolas.muller@xxxxxxxxx>
---
.../watchdog/tco-wdt-warning-interrupt.txt | 85 ++++++++++++++++++++
drivers/watchdog/Kconfig | 13 +++
drivers/watchdog/iTCO_wdt.c | 80 ++++++++++++++++++
3 files changed, 178 insertions(+)
create mode 100644 Documentation/watchdog/tco-wdt-warning-interrupt.txt
diff --git a/Documentation/watchdog/tco-wdt-warning-interrupt.txt b/Documentation/watchdog/tco-wdt-warning-interrupt.txt
new file mode 100644
index 0000000..2e4eebf
--- /dev/null
+++ b/Documentation/watchdog/tco-wdt-warning-interrupt.txt
@@ -0,0 +1,85 @@
+Last reviewed: 02/12/2015
+
+ TCO watchdog warning interrupt
+ handled by drivers/watchdog/iTCO_wdt.c
+ Documentation and code by
+ Francois-Nicolas Muller <francois-nicolas.muller@xxxxxxxxx>
+
+
+Introduction
+------------
+Intel TCO watchdog is intended to detect and recover from locks up of the
+platform. It contains a countdown timer, that should be reloaded on-time by
+software before reaching zero.
+
+If the platform locks up and is not able to reload the timer, then when it
+reaches zero:
+- the timer is automatically reloaded with 04h and starts decrementing again,
+- timeout bit is set in TCO1_STS register,
+- SMI or SCI interrupt is generated (optional).
+
+If it reaches zero a second time while timeout bit is set,
+- second_to_sts bit is set,
+- reset of the platform is initiated.
+
+At first timeout, the SMI (or SCI) can be used to provide debug information
+about the system state and help on fixing the cause of the hang. This is the
+"warning interrupt".
+
+Warning interrupt
+-----------------
+Warning interrupt handler is called when system is hung, so it is useful to
+gather maximum information about system state at this point for root-causing the
+issue.
+
+When the interrupt occurs,
+- call stacks of all running cpus are dumped,
+- panic() is called (optional)
+
+Enabling the warning interrupt
+------------------------------
+Boot parameter "warn_irq" (boolean) enables warning interrupt generation at
+first timer expiration (disabled by default).
+
+As this is a command line option, configuration can be changed easily without
+building again the code.
+
+Enabling panic upon warning interrupt
+-------------------------------------
+Warning interrupt handler can call panic() when Kconfig option
+CONFIG_ITCO_WARNING_PANIC is set.
+
+panic() call is useful in case of some panic handlers have been registered and
+need to be run at this time.
+
+When CONFIG_ITCO_WARN_PANIC is set,
+- If CONFIG_PANIC_TIMEOUT is zero or greater than 3 seconds, TCO watchdog will
+ reset the platform if second expiration happens before TCO has been kicked
+ again.
+- If CONFIG_PANIC_TIMEOUT is < 0, platform will reboot immediately (emergency
+ restart procedure).
+- If CONFIG_PANIC_TIMEOUT is 1 or 2 seconds, platform will reboot after 1 or 2
+ seconds delay (emergency restart procedure).
+
+SCI vs SMI
+----------
+For the moment, the TCO watchdog warning interrupt feature is only available for
+platforms that are able to trigger a SCI upon first expiration of TCO watchdog.
+
+There is no support of the SMI option yet.
+
+ACPI configuration
+------------------
+Bios is configuring the GPE associated to the warning interrupt. The driver uses
+acpi tables to get the GPE number.
+
+This change is intended for Intel Cherrytrail platform. As TCO watchdog is part
+of lpc_ich module, its _HID is used in the driver to retrieve GPE configuration
+from Bios.
+
+If no GPE information is provided by the Bios, the interrupt is not handled and
+appears in the dmesg log as a warning. Second timeout is still able to trigger a
+reset.
+
+-- Francois-Nicolas Muller
+ (francois-nicolas.muller@xxxxxxxxx)
diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
index 79d2589..41f3647 100644
--- a/drivers/watchdog/Kconfig
+++ b/drivers/watchdog/Kconfig
@@ -674,6 +674,19 @@ config ITCO_VENDOR_SUPPORT
devices. At this moment we only have additional support for some
SuperMicro Inc. motherboards.
+config ITCO_WARNING_PANIC
+ bool "Intel TCO Timer/Watchdog panic on warning interrupt"
+ depends on ITCO_WDT && ACPI
+ default y
+ ---help---
+ Force a call to panic() when TCO warning interrupt occurs.
+
+ Warning interrupt happens if warn_irq module parameter is set and
+ TCO timer first expires.
+
+ If not set, only cpu backtraces are dumped, no call to panic() and
+ no notification of panic are done.
+
config IT8712F_WDT
tristate "IT8712F (Smart Guardian) Watchdog Timer"
depends on X86
diff --git a/drivers/watchdog/iTCO_wdt.c b/drivers/watchdog/iTCO_wdt.c
index e802a54..a25794c 100644
--- a/drivers/watchdog/iTCO_wdt.c
+++ b/drivers/watchdog/iTCO_wdt.c
@@ -49,6 +49,8 @@
/* Module and version information */
#define DRV_NAME "iTCO_wdt"
#define DRV_VERSION "1.11"
+#define DRV_NAME_ACPI "iTCO_wdt_wirq"
+#define TCO_CLASS DRV_NAME
/* Includes */
#include <linux/module.h> /* For module specific items */
@@ -68,6 +70,11 @@
#include <linux/pm.h> /* For suspend/resume */
#include <linux/mfd/core.h>
#include <linux/mfd/lpc_ich.h>
+#include <linux/nmi.h>
+#ifdef CONFIG_ACPI
+#include <linux/acpi.h>
+#include <acpi/actypes.h>
+#endif
#include "iTCO_vendor.h"
@@ -107,6 +114,14 @@ static struct { /* this is private data for the iTCO_wdt device */
bool started;
} iTCO_wdt_private;
+#ifdef CONFIG_ACPI
+static const struct acpi_device_id iTCO_wdt_ids[] = {
+ {"8086229C", 0},
+ {"", 0},
+};
+MODULE_DEVICE_TABLE(acpi, iTCO_wdt_ids);
+#endif
+
/* module parameters */
#define WATCHDOG_TIMEOUT 30 /* 30 sec default heartbeat */
static int heartbeat = WATCHDOG_TIMEOUT; /* in seconds */
@@ -126,6 +141,15 @@ module_param(turn_SMI_watchdog_clear_off, int, 0);
MODULE_PARM_DESC(turn_SMI_watchdog_clear_off,
"Turn off SMI clearing watchdog (depends on TCO-version)(default=1)");
+static bool warn_irq;
+module_param(warn_irq, bool, 0);
+MODULE_PARM_DESC(warn_irq,
+ "Dump all cpus backtraces at first watchdog timer expiration (default=0)");
+
+#ifdef CONFIG_ACPI
+static bool warn_irq_panic = CONFIG_ITCO_WARNING_PANIC;
+#endif
+
/*
* Some TCO specific functions
*/
@@ -200,6 +224,37 @@ static int iTCO_wdt_unset_NO_REBOOT_bit(void)
return ret; /* returns: 0 = OK, -EIO = Error */
}
+#ifdef CONFIG_ACPI
+static u32 iTCO_wdt_wirq(acpi_handle gpe_device, u32 gpe, void *context)
+{
+ trigger_all_cpu_backtrace();
+ if (warn_irq_panic)
+ panic("Kernel Watchdog");
+
+ return IRQ_HANDLED;
+}
+
+static int iTCO_wdt_acpi_add(struct acpi_device *device)
+{
+ unsigned long long gpe;
+ acpi_status status;
+
+ status = acpi_evaluate_integer(device->handle, "_GPE", NULL, &gpe);
+ if (ACPI_FAILURE(status))
+ return -EINVAL;
+
+ status = acpi_install_gpe_handler(NULL, gpe, ACPI_GPE_EDGE_TRIGGERED,
+ iTCO_wdt_wirq, NULL);
+ if (ACPI_FAILURE(status))
+ return -ENODEV;
+
+ acpi_enable_gpe(NULL, gpe);
+
+ pr_debug("interrupt=SCI GPE=0x%02llx", gpe);
+ return 0;
+}
+#endif
+
static int iTCO_wdt_start(struct watchdog_device *wd_dev)
{
unsigned int val;
@@ -628,6 +683,17 @@ static struct platform_driver iTCO_wdt_driver = {
},
};
+#ifdef CONFIG_ACPI
+static struct acpi_driver iTCO_wdt_acpi_driver = {
+ .name = DRV_NAME_ACPI,
+ .class = TCO_CLASS,
+ .ids = iTCO_wdt_ids,
+ .ops = {
+ .add = iTCO_wdt_acpi_add,
+ },
+};
+#endif
+
static int __init iTCO_wdt_init_module(void)
{
int err;
@@ -638,12 +704,26 @@ static int __init iTCO_wdt_init_module(void)
if (err)
return err;
+#ifdef CONFIG_ACPI
+ if (warn_irq) {
+ err = acpi_bus_register_driver(&iTCO_wdt_acpi_driver);
+ if (err) {
+ platform_driver_unregister(&iTCO_wdt_driver);
+ return err;
+ }
+ }
+#endif
+
return 0;
}
static void __exit iTCO_wdt_cleanup_module(void)
{
platform_driver_unregister(&iTCO_wdt_driver);
+#ifdef CONFIG_ACPI
+ if (warn_irq)
+ acpi_bus_unregister_driver(&iTCO_wdt_acpi_driver);
+#endif
pr_info("Watchdog Module Unloaded\n");
}
--
1.7.9.5
-----Original Message-----
From: Rafael J. Wysocki [mailto:rjw@xxxxxxxxxxxxx]
Sent: Tuesday, January 20, 2015 4:00 PM
To: Muller, Francois-nicolas
Cc: Guenter Roeck; Darren Hart; 'platform-driver-x86@xxxxxxxxxxxxxxx'; Linux ACPI Mailing List; linux-watchdog@xxxxxxxxxxxxxxx; Wim Van Sebroeck
Subject: Re: [PATCH] TCO Watchdog warning interrupt driver creation
On Wednesday, January 14, 2015 04:38:49 PM Muller, Francois-nicolas wrote:
> From 54d2ff5e13c1b35d5019b82376dabb903ebe30d6 Mon Sep 17 00:00:00 2001
> From: Francois-Nicolas Muller <francois-nicolas.muller@xxxxxxxxx>
> Date: Wed, 14 Jan 2015 14:27:43 +0100
> Subject: [PATCH] Adding TCO watchdog warning interrupt handling.
>
> This feature is useful to root cause watchdog expiration.
> It is activated by boot parameter 'warn_irq' (disabled by default).
>
> Upon first expiration of the TCO watchdog, a warning interrupt is
> fired then the interrupt handler dumps registers and call stack of all available cores.
>
> Finally panic() is called and notifies the panic handlers if any. At
> the same time, the TCO watchdog reloads with 2.4 seconds timeout value.
>
> When warning interrupt is enabled, platform reboot depends on
> CONFIG_PANIC_TIMEOUT value :
>
> - If CONFIG_PANIC_TIMEOUT is zero or greater than 3 seconds, TCO
> watchdog will reset the platform if second expiration happens before
> TCO has been kicked again.
>
> - If CONFIG_PANIC_TIMEOUT is < 0, platform will reboot immediately
> (emergency restart procedure).
>
> - If CONFIG_PANIC_TIMEOUT is 1 or 2 seconds, platform will reboot
> after 1 or 2 seconds delay (emergency restart procedure).
>
> Change-Id: I009c41f2f3dc3bd091b4d2a45b4ea0be85c8ce27
> Signed-off-by: Francois-Nicolas Muller
> <francois-nicolas.muller@xxxxxxxxx>
> ---
> drivers/watchdog/iTCO_wdt.c | 64
> +++++++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 64 insertions(+)
>
> diff --git a/drivers/watchdog/iTCO_wdt.c b/drivers/watchdog/iTCO_wdt.c
> index e802a54..a8c16d2 100644
> --- a/drivers/watchdog/iTCO_wdt.c
> +++ b/drivers/watchdog/iTCO_wdt.c
> @@ -49,6 +49,8 @@
> /* Module and version information */
> #define DRV_NAME "iTCO_wdt"
> #define DRV_VERSION "1.11"
> +#define DRV_NAME_ACPI "iTCO_wdt_wirq"
> +#define TCO_CLASS DRV_NAME
>
> /* Includes */
> #include <linux/module.h> /* For module specific items */
> @@ -68,6 +70,9 @@
> #include <linux/pm.h> /* For suspend/resume */
> #include <linux/mfd/core.h>
> #include <linux/mfd/lpc_ich.h>
> +#include <linux/nmi.h>
> +#include <linux/acpi.h>
> +#include <acpi/actypes.h>
>
> #include "iTCO_vendor.h"
>
> @@ -107,6 +112,12 @@ static struct { /* this is private data for the iTCO_wdt device */
> bool started;
> } iTCO_wdt_private;
>
> +static const struct acpi_device_id iTCO_wdt_ids[] = {
> + {"8086229C", 0},
This is not a proper ACPI or PNP device name as far as I can say.
What is it?
> + {"", 0},
> +};
> +MODULE_DEVICE_TABLE(acpi, iTCO_wdt_ids);
> +
> /* module parameters */
> #define WATCHDOG_TIMEOUT 30 /* 30 sec default heartbeat */
> static int heartbeat = WATCHDOG_TIMEOUT; /* in seconds */ @@ -126,6
> +137,11 @@ module_param(turn_SMI_watchdog_clear_off, int, 0);
> MODULE_PARM_DESC(turn_SMI_watchdog_clear_off,
> "Turn off SMI clearing watchdog (depends on
> TCO-version)(default=1)");
>
> +static bool warn_irq;
> +module_param(warn_irq, bool, 0);
> +MODULE_PARM_DESC(warn_irq,
> + "Watchdog trigs a panic at first expiration (default=0)");
> +
> /*
> * Some TCO specific functions
> */
> @@ -200,6 +216,35 @@ static int iTCO_wdt_unset_NO_REBOOT_bit(void)
> return ret; /* returns: 0 = OK, -EIO = Error */ }
>
> +static u32 iTCO_wdt_wirq(acpi_handle gpe_device, u32 gpe, void
> +*context) {
> + trigger_all_cpu_backtrace();
> + panic("Kernel Watchdog");
> +
> + /* This code should not be reached */
> + return IRQ_HANDLED;
> +}
> +
> +static int iTCO_wdt_acpi_add(struct acpi_device *device) {
> + unsigned long long gpe;
> + acpi_status status;
> +
The code below seems to mean: "If the device _HID returns '8086229C', there should be a _GPE object under it which then returns the number of the GPE to bind to within the FADT GPE blocks."
Where is this documented?
> + status = acpi_evaluate_integer(device->handle, "_GPE", NULL, &gpe);
> + if (ACPI_FAILURE(status))
> + return -EINVAL;
> +
> + status = acpi_install_gpe_handler(NULL, gpe, ACPI_GPE_EDGE_TRIGGERED,
> + iTCO_wdt_wirq, NULL);
> + if (ACPI_FAILURE(status))
> + return -ENODEV;
> +
> + acpi_enable_gpe(NULL, gpe);
> +
> + pr_debug("interrupt=SCI GPE=0x%02llx", gpe);
> + return 0;
> +}
> +
> static int iTCO_wdt_start(struct watchdog_device *wd_dev) {
> unsigned int val;
> @@ -628,6 +673,15 @@ static struct platform_driver iTCO_wdt_driver = {
> },
> };
>
> +static struct acpi_driver iTCO_wdt_acpi_driver = {
> + .name = DRV_NAME_ACPI,
> + .class = TCO_CLASS,
> + .ids = iTCO_wdt_ids,
> + .ops = {
> + .add = iTCO_wdt_acpi_add,
> + },
> +};
> +
> static int __init iTCO_wdt_init_module(void) {
> int err;
> @@ -638,12 +692,22 @@ static int __init iTCO_wdt_init_module(void)
> if (err)
> return err;
>
> + if (warn_irq) {
> + err = acpi_bus_register_driver(&iTCO_wdt_acpi_driver);
> + if (err) {
> + platform_driver_unregister(&iTCO_wdt_driver);
> + return err;
> + }
> + }
> +
> return 0;
> }
>
> static void __exit iTCO_wdt_cleanup_module(void) {
> platform_driver_unregister(&iTCO_wdt_driver);
> + if (warn_irq)
> + acpi_bus_unregister_driver(&iTCO_wdt_acpi_driver);
> pr_info("Watchdog Module Unloaded\n"); }
>
> --
> 1.9.1
And does it build for CONFIG_ACPI unset?
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