• Mika Westerberg's avatar
    ACPI / watchdog: Add support for WDAT hardware watchdog · 058dfc76
    Mika Westerberg authored
    Starting from Intel Skylake the iTCO watchdog timer registers were moved to
    reside in the same register space with SMBus host controller.  Not all
    needed registers are available though and we need to unhide P2SB (Primary
    to Sideband) device briefly to be able to read status of required NO_REBOOT
    bit. The i2c-i801.c SMBus driver used to handle this and creation of the
    iTCO watchdog platform device.
    
    Windows, on the other hand, does not use the iTCO watchdog hardware
    directly even if it is available. Instead it relies on ACPI Watchdog Action
    Table (WDAT) table to describe the watchdog hardware to the OS. This table
    contains necessary information about the the hardware and also set of
    actions which are executed by a driver as needed.
    
    This patch implements a new watchdog driver that takes advantage of the
    ACPI WDAT table. We split the functionality into two parts: first part
    enumerates the WDAT table and if found, populates resources and creates
    platform device for the actual driver. The second part is the driver
    itself.
    
    The reason for the split is that this way we can make the driver itself to
    be a module and loaded automatically if the WDAT table is found. Otherwise
    the module is not loaded.
    Signed-off-by: default avatarMika Westerberg <mika.westerberg@linux.intel.com>
    Reviewed-by: default avatarGuenter Roeck <linux@roeck-us.net>
    Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
    058dfc76
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