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SubjectRe: [PATCH v2] iTCO_wdt: all versions count down twice
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On 06/04/2017 13:46, Guenter Roeck wrote:
> On 04/05/2017 04:41 AM, Paolo Bonzini wrote:
>> The ICH9 is listed as having TCO v2, and indeed the behavior in the
>> datasheet corresponds to v2 (for example the NO_REBOOT flag is
>> accessible via the 16KiB-aligned Root Complex Base Address).
>>
>> However, the TCO counts twice just like in v1; the documentation
>> of the SECOND_TO_STS bit says: "ICH9 sets this bit to 1 to indicate
>> that the TIMEOUT bit had been (or is currently) set and a second
>> timeout occurred before the TCO_RLD register was written. If this
>> bit is set and the NO_REBOOT config bit is 0, then the ICH9 will
>> reboot the system after the second timeout. The same can be found
>> in the BayTrail (Atom E3800) datasheet, and even HOWTOs around
>> the Internet say that it will reboot after _twice_ the specified
>> heartbeat.
>>
>> I did not find the Apollo Lake datasheet, but because v4/v5 has
>> a SECOND_TO_STS bit just like the previous version I'm enabling
>> this for Apollo Lake as well.
>>
>> Cc: Wim Van Sebroeck <wim@iguana.be>
>> Cc: Guenter Roeck <linux@roeck-us.net>
>> Cc: linux-watchdog@vger.kernel.org
>> Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
>> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
>
> Reviewed-by: Guenter Roeck <linux@roeck-us.net>

Wim, has this been included in a tree for 4.12? The trees at
linux-watchdog.git still seem empty.

Thanks,

Paolo

>> ---
>> Documentation/watchdog/watchdog-parameters.txt | 2 +-
>> drivers/watchdog/iTCO_wdt.c | 22 ++++++++++------------
>> 2 files changed, 11 insertions(+), 13 deletions(-)
>>
>> diff --git a/Documentation/watchdog/watchdog-parameters.txt
>> b/Documentation/watchdog/watchdog-parameters.txt
>> index 4f7d86dd0a5d..914518aeb972 100644
>> --- a/Documentation/watchdog/watchdog-parameters.txt
>> +++ b/Documentation/watchdog/watchdog-parameters.txt
>> @@ -117,7 +117,7 @@ nowayout: Watchdog cannot be stopped once started
>> -------------------------------------------------
>> iTCO_wdt:
>> heartbeat: Watchdog heartbeat in seconds.
>> - (2<heartbeat<39 (TCO v1) or 613 (TCO v2), default=30)
>> + (5<=heartbeat<=74 (TCO v1) or 1226 (TCO v2), default=30)
>> nowayout: Watchdog cannot be stopped once started
>> (default=kernel config parameter)
>> -------------------------------------------------
>> diff --git a/drivers/watchdog/iTCO_wdt.c b/drivers/watchdog/iTCO_wdt.c
>> index 3d0abc0d59b4..d1d0446011c4 100644
>> --- a/drivers/watchdog/iTCO_wdt.c
>> +++ b/drivers/watchdog/iTCO_wdt.c
>> @@ -280,16 +280,15 @@ static int iTCO_wdt_ping(struct watchdog_device
>> *wd_dev)
>>
>> iTCO_vendor_pre_keepalive(p->smi_res, wd_dev->timeout);
>>
>> + /* Reset the timeout status bit so that the timer
>> + * needs to count down twice again before rebooting */
>> + outw(0x0008, TCO1_STS(p)); /* write 1 to clear bit */
>> +
>> /* Reload the timer by writing to the TCO Timer Counter register */
>> - if (p->iTCO_version >= 2) {
>> + if (p->iTCO_version >= 2)
>> outw(0x01, TCO_RLD(p));
>> - } else if (p->iTCO_version == 1) {
>> - /* Reset the timeout status bit so that the timer
>> - * needs to count down twice again before rebooting */
>> - outw(0x0008, TCO1_STS(p)); /* write 1 to clear bit */
>> -
>> + else if (p->iTCO_version == 1)
>> outb(0x01, TCO_RLD(p));
>> - }
>>
>> spin_unlock(&p->io_lock);
>> return 0;
>> @@ -302,11 +301,8 @@ static int iTCO_wdt_set_timeout(struct
>> watchdog_device *wd_dev, unsigned int t)
>> unsigned char val8;
>> unsigned int tmrval;
>>
>> - tmrval = seconds_to_ticks(p, t);
>> -
>> - /* For TCO v1 the timer counts down twice before rebooting */
>> - if (p->iTCO_version == 1)
>> - tmrval /= 2;
>> + /* The timer counts down twice before rebooting */
>> + tmrval = seconds_to_ticks(p, t) / 2;
>>
>> /* from the specs: */
>> /* "Values of 0h-3h are ignored and should not be attempted" */
>> @@ -359,6 +355,8 @@ static unsigned int iTCO_wdt_get_timeleft(struct
>> watchdog_device *wd_dev)
>> spin_lock(&p->io_lock);
>> val16 = inw(TCO_RLD(p));
>> val16 &= 0x3ff;
>> + if (!(inw(TCO1_STS(p)) & 0x0008))
>> + val16 += (inw(TCOv2_TMR(p)) & 0x3ff);
>> spin_unlock(&p->io_lock);
>>
>> time_left = ticks_to_seconds(p, val16);
>>
>
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