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[WATCHDOG] iTCO_wdt: Fix ICH7+ reboot issue.

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Bugzilla: 9868 & 10195.
There seems to be a bug into the SMM code that handles TCO Timeout SMI.
Andriy Gapon found that the code on his DG33TL system does the following:
> The handler is quite simple - it tests value in TCO1_CNT against 0x800, i.e.
> checks TCO_TMR_HLT. If the bit is set the handler goes into an infinite loop,
> apparently to allow the second timeout and reboot. Otherwise it simply clears
> TIMEOUT bit in TCO1_STS and that's it.
> So the logic seems to be reversed, because it is hard to see how TIMEOUT can
> get set to 1 and SMI generated when TCO_TMR_HLT is set (other than a
> transitional effect).

The only trick we have is to bypass the SMM code by turning of the generation
of the SMI#. The trick can only be enabled by setting the vendorsupport module
parameter to 911. This trick doesn't work well on laptop's.

Note: this is a dirty hack. Please handle with care. The only real fix is that
the bug in the SMM bios code get's fixed.

Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
This commit is contained in:
Wim Van Sebroeck 2009-06-08 17:41:51 +00:00
parent de8cd9a306
commit 55e8ddecec
1 changed files with 76 additions and 6 deletions
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82
drivers/watchdog/iTCO_vendor_support.c
View file

@ -19,7 +19,7 @@
/* Module and version information */
#define DRV_NAME "iTCO_vendor_support"
#define DRV_VERSION "1.03"
#define DRV_VERSION "1.04"
#define PFX DRV_NAME ": "
/* Includes */
@ -44,11 +44,14 @@
#define SUPERMICRO_OLD_BOARD 1
/* SuperMicro Pentium 4 / Xeon 4 / EMT64T Era Systems */
#define SUPERMICRO_NEW_BOARD 2
/* Broken BIOS */
#define BROKEN_BIOS 911
static int vendorsupport;
module_param(vendorsupport, int, 0);
MODULE_PARM_DESC(vendorsupport, "iTCO vendor specific support mode, default="
"0 (none), 1=SuperMicro Pent3, 2=SuperMicro Pent4+");
"0 (none), 1=SuperMicro Pent3, 2=SuperMicro Pent4+, "
"911=Broken SMI BIOS");
/*
* Vendor Specific Support
@ -242,6 +245,59 @@ static void supermicro_new_pre_set_heartbeat(unsigned int heartbeat)
supermicro_new_lock_watchdog();
}
/*
* Vendor Support: 911
* Board: Some Intel ICHx based motherboards
* iTCO chipset: ICH7+
*
* Some Intel motherboards have a broken BIOS implementation: i.e.
* the SMI handler clear's the TIMEOUT bit in the TC01_STS register
* and does not reload the time. Thus the TCO watchdog does not reboot
* the system.
*
* These are the conclusions of Andriy Gapon <avg@icyb.net.ua> after
* debugging: the SMI handler is quite simple - it tests value in
* TCO1_CNT against 0x800, i.e. checks TCO_TMR_HLT. If the bit is set
* the handler goes into an infinite loop, apparently to allow the
* second timeout and reboot. Otherwise it simply clears TIMEOUT bit
* in TCO1_STS and that's it.
* So the logic seems to be reversed, because it is hard to see how
* TIMEOUT can get set to 1 and SMI generated when TCO_TMR_HLT is set
* (other than a transitional effect).
*
* The only fix found to get the motherboard(s) to reboot is to put
* the glb_smi_en bit to 0. This is a dirty hack that bypasses the
* broken code by disabling Global SMI.
*
* WARNING: globally disabling SMI could possibly lead to dramatic
* problems, especially on laptops! I.e. various ACPI things where
* SMI is used for communication between OS and firmware.
*
* Don't use this fix if you don't need to!!!
*/
static void broken_bios_start(unsigned long acpibase)
{
unsigned long val32;
val32 = inl(SMI_EN);
/* Bit 13: TCO_EN -> 0 = Disables TCO logic generating an SMI#
Bit 0: GBL_SMI_EN -> 0 = No SMI# will be generated by ICH. */
val32 &= 0xffffdffe;
outl(val32, SMI_EN);
}
static void broken_bios_stop(unsigned long acpibase)
{
unsigned long val32;
val32 = inl(SMI_EN);
/* Bit 13: TCO_EN -> 1 = Enables TCO logic generating an SMI#
Bit 0: GBL_SMI_EN -> 1 = Turn global SMI on again. */
val32 |= 0x00002001;
outl(val32, SMI_EN);
}
/*
* Generic Support Functions
*/
@ -249,19 +305,33 @@ static void supermicro_new_pre_set_heartbeat(unsigned int heartbeat)
void iTCO_vendor_pre_start(unsigned long acpibase,
unsigned int heartbeat)
{
if (vendorsupport == SUPERMICRO_OLD_BOARD)
switch (vendorsupport) {
case SUPERMICRO_OLD_BOARD:
supermicro_old_pre_start(acpibase);
else if (vendorsupport == SUPERMICRO_NEW_BOARD)
break;
case SUPERMICRO_NEW_BOARD:
supermicro_new_pre_start(heartbeat);
break;
case BROKEN_BIOS:
broken_bios_start(acpibase);
break;
}
}
EXPORT_SYMBOL(iTCO_vendor_pre_start);
void iTCO_vendor_pre_stop(unsigned long acpibase)
{
if (vendorsupport == SUPERMICRO_OLD_BOARD)
switch (vendorsupport) {
case SUPERMICRO_OLD_BOARD:
supermicro_old_pre_stop(acpibase);
else if (vendorsupport == SUPERMICRO_NEW_BOARD)
break;
case SUPERMICRO_NEW_BOARD:
supermicro_new_pre_stop();
break;
case BROKEN_BIOS:
broken_bios_stop(acpibase);
break;
}
}
EXPORT_SYMBOL(iTCO_vendor_pre_stop);