On Tue, Dec 06, 2016 at 04:18:15AM +0530, Julius Hemanth Pitti wrote: > 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. >
Not really sure how to handle this. The registers accessed are definitely not available on all versions of the iTCO watchdog, so it would have to be enabled on a per chip version basis. Old versions of Intel documents state that bit 9 of TCO1_CNT must not be changed, and list bit 8 as reserved. Also, doesn't using the NMI/SMI to detect the timeout mean that the watchdog fires earlier ? Then there is the question if this would be better handled using the pretimeout framework. Guenter > Cc: [email protected] > Cc: [email protected] > Signed-off-by: Julius Hemanth Pitti <[email protected]> > --- > 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) { Yoda programming in kernel not desirable is (even more so if used inconsistently). > + val &= ~(NMI2SMI_EN); Unnecessary ( ) > + 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 >
