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iTCO_wdt: mask NMI_NOW bit for update_no_reboot_bit() call

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[ Upstream commit daa814d784ac034c62ab3fb0ef83daeafef527e2 ]

Commit da23b6faa8bf ("watchdog: iTCO: Add support for Cannon Lake
PCH iTCO") does not mask NMI_NOW bit during TCO1_CNT register's
value comparison for update_no_reboot_bit() call causing following
failure:

   ...
   iTCO_vendor_support: vendor-support=0
   iTCO_wdt iTCO_wdt: unable to reset NO_REBOOT flag, device
                                    disabled by hardware/BIOS
   ...

and this can lead to unexpected NMIs later during regular
crashkernel's workflow because of watchdog probe call failures.

This change masks NMI_NOW bit for TCO1_CNT register values to
avoid unexpected NMI_NOW bit inversions.

Fixes: da23b6faa8bf ("watchdog: iTCO: Add support for Cannon Lake PCH iTCO")
Signed-off-by: Oleksandr Ocheretnyi <oocheret@cisco.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Link: https://lore.kernel.org/r/20240913191403.2560805-1-oocheret@cisco.com
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Oleksandr Ocheretnyi 2024-09-13 12:14:03 -07:00 committed by Greg Kroah-Hartman
parent d17b991ac4
commit 0bcea01215
1 changed files with 19 additions and 2 deletions
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21
drivers/watchdog/iTCO_wdt.c
View File

@ -82,6 +82,13 @@
#define TCO2_CNT(p) (TCOBASE(p) + 0x0a) /* TCO2 Control Register */ #define TCO2_CNT(p) (TCOBASE(p) + 0x0a) /* TCO2 Control Register */
#define TCOv2_TMR(p) (TCOBASE(p) + 0x12) /* TCOv2 Timer Initial Value*/ #define TCOv2_TMR(p) (TCOBASE(p) + 0x12) /* TCOv2 Timer Initial Value*/
/*
* NMI_NOW is bit 8 of TCO1_CNT register
* Read/Write
* This bit is implemented as RW but has no effect on HW.
*/
#define NMI_NOW BIT(8)
/* internal variables */ /* internal variables */
struct iTCO_wdt_private { struct iTCO_wdt_private {
struct watchdog_device wddev; struct watchdog_device wddev;
@ -219,13 +226,23 @@ static int update_no_reboot_bit_cnt(void *priv, bool set)
struct iTCO_wdt_private *p = priv; struct iTCO_wdt_private *p = priv;
u16 val, newval; u16 val, newval;
val = inw(TCO1_CNT(p)); /*
* writing back 1b1 to NMI_NOW of TCO1_CNT register
* causes NMI_NOW bit inversion what consequently does
* not allow to perform the register's value comparison
* properly.
*
* NMI_NOW bit masking for TCO1_CNT register values
* helps to avoid possible NMI_NOW bit inversions on
* following write operation.
*/
val = inw(TCO1_CNT(p)) & ~NMI_NOW;
if (set) if (set)
val |= BIT(0); val |= BIT(0);
else else
val &= ~BIT(0); val &= ~BIT(0);
outw(val, TCO1_CNT(p)); outw(val, TCO1_CNT(p));
newval = inw(TCO1_CNT(p)); newval = inw(TCO1_CNT(p)) & ~NMI_NOW;
/* make sure the update is successful */ /* make sure the update is successful */
return val != newval ? -EIO : 0; return val != newval ? -EIO : 0;