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Message-Id: <20161205224815.23335-1-jpitti@cisco.com>
Date: Tue, 6 Dec 2016 04:18:15 +0530
From: Julius Hemanth Pitti <jpitti@...co.com>
To: Wim Van Sebroeck <wim@...ana.be>,
Guenter Roeck <linux@...ck-us.net>
Cc: xe-kernel@...ernal.cisco.com, jpitti@...sta.com,
linux-watchdog@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [RFC] watchdog: iTCO_wdt: Introduce panic_on_timeout module param
Currently iTCO_wdt silently resets the board when timeout
occurs.
This patch introduces new "panic_on_timeout" module param,
which when set allows the iTCO_wdt to call panic when
watchdog timeout occurs, this help to boot to crash
kernel and collect core dump for further analysis.
Cc: xe-kernel@...ernal.cisco.com
Cc: jpitti@...sta.com
Signed-off-by: Julius Hemanth Pitti <jpitti@...co.com>
---
drivers/watchdog/iTCO_wdt.c | 61 +++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 61 insertions(+)
diff --git a/drivers/watchdog/iTCO_wdt.c b/drivers/watchdog/iTCO_wdt.c
index 06fcb6c..23ddcf4 100644
--- a/drivers/watchdog/iTCO_wdt.c
+++ b/drivers/watchdog/iTCO_wdt.c
@@ -66,6 +66,7 @@
#include <linux/spinlock.h> /* For spin_lock/spin_unlock/... */
#include <linux/uaccess.h> /* For copy_to_user/put_user/... */
#include <linux/io.h> /* For inb/outb/... */
+#include <linux/nmi.h>
#include <linux/platform_data/itco_wdt.h>
#include "iTCO_vendor.h"
@@ -76,6 +77,24 @@
/* SMI Control and Enable Register */
#define SMI_EN (iTCO_wdt_private.smi_res->start)
+static int panic_on_timeout;
+module_param(panic_on_timeout, int, 0);
+MODULE_PARM_DESC(panic_on_timeout,
+ "Panic on NMI instead of Reset (1 = panic), default=0.");
+
+/* NMI2SMI_EN is bit 9 of TCO1_CNT register
+ * Read/Write
+ * 0 = Normal NMI functionality.
+ * 1 = Forces all NMIs to instead cause SMIs
+ * This depends on NMI_EN and GBL_SMI_EN bits.
+ */
+#define NMI2SMI_EN (1 << 9)
+
+/* NMI_NOW is bit 8 of TCO1_CNT register.
+ * Read/'Write to Clear'
+ */
+#define NMI_NOW (1 << 8)
+
#define TCO_RLD (TCOBASE + 0x00) /* TCO Timer Reload and Curr. Value */
#define TCOv1_TMR (TCOBASE + 0x01) /* TCOv1 Timer Initial Value */
#define TCO_DAT_IN (TCOBASE + 0x02) /* TCO Data In Register */
@@ -236,6 +255,15 @@ static int iTCO_wdt_start(struct watchdog_device *wd_dev)
val &= 0xf7ff;
outw(val, TCO1_CNT);
val = inw(TCO1_CNT);
+
+ if (panic_on_timeout) {
+ /* Make sure NMIs are allowed to fire */
+ if (NMI2SMI_EN & val) {
+ val &= ~(NMI2SMI_EN);
+ outw(val, TCO1_CNT);
+ pr_info("NMIs are no longer routed to SMIs\n");
+ }
+ }
spin_unlock(&iTCO_wdt_private.io_lock);
if (val & 0x0800)
@@ -422,6 +450,26 @@ static void iTCO_wdt_cleanup(void)
iTCO_wdt_private.gcs_pmc = NULL;
}
+/*
+ * iTCO_wdt_timeout_handler: Handler for watchdog timeout NMI event.
+ */
+int iTCO_wdt_timeout_handler(unsigned int ulReason, struct pt_regs *regs)
+{
+ unsigned long val32 = inw(TCO1_CNT);
+
+ if (val32 & NMI_NOW) {
+ /* Clear NMI - Bit 8 within TCO1_CNT is write to clear */
+ outw(val32, TCO1_CNT);
+
+ /* Crash the system */
+ nmi_panic(regs, "iTCO_wdt: Watchdog timeout");
+
+ /* Never returns */
+ return NMI_HANDLED;
+ }
+ return NMI_DONE;
+}
+
static int iTCO_wdt_probe(struct platform_device *dev)
{
int ret = -ENODEV;
@@ -552,11 +600,21 @@ static int iTCO_wdt_probe(struct platform_device *dev)
goto unreg_tco;
}
+ if (panic_on_timeout) {
+ ret = register_nmi_handler(NMI_UNKNOWN, iTCO_wdt_timeout_handler, 0, "iTCO_wdt");
+ if (ret != 0) {
+ pr_err("cannot register NMI Handler for iTCO_wdt watchdog (err=%d)\n", ret);
+ goto unreg_wd;
+ }
+ }
+
pr_info("initialized. heartbeat=%d sec (nowayout=%d)\n",
heartbeat, nowayout);
return 0;
+unreg_wd:
+ watchdog_unregister_device(&iTCO_wdt_watchdog_dev);
unreg_tco:
release_region(iTCO_wdt_private.tco_res->start,
resource_size(iTCO_wdt_private.tco_res));
@@ -581,6 +639,9 @@ static int iTCO_wdt_probe(struct platform_device *dev)
static int iTCO_wdt_remove(struct platform_device *dev)
{
+ if (panic_on_timeout)
+ unregister_nmi_handler(NMI_UNKNOWN, "iTCO_wdt");
+
if (iTCO_wdt_private.tco_res || iTCO_wdt_private.smi_res)
iTCO_wdt_cleanup();
--
2.10.1
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