Martin noticed that nct6775 driver does not load properly on his system
in v5.4+ kernels. The issue was bisected to commit b84398d6 ("i2c:
i801: Use iTCO version 6 in Cannon Lake PCH and beyond") but it is
likely not the culprit because the faulty code has been in the driver
already since commit 94246930 ("i2c: i801: Create iTCO device on
newer Intel PCHs"). So more likely some commit that added PCI IDs of
recent chipsets made the driver to create the iTCO_wdt device on Martins
system.

The issue was debugged to be PCI configuration access to the PMC device
that is not present. This returns all 1's when read and this caused the
iTCO_wdt driver to accidentally request resourses used by nct6775.

It turns out that the SMI resource is only required for some ancient
systems, not the ones supported by this driver. For this reason do not
populate the SMI resource at all and drop all the related code. The
driver now always populates the main I/O resource and only in case of SPT
(Intel Sunrisepoint) compatible devices it adds another resource for the
NO_REBOOT bit. These two resources are of different types so
platform_get_resource() used by the iTCO_wdt driver continues to find
the both resources at index 0.

Link: https://lore.kernel.org/linux-hwmon/CAM1AHpQ4196tyD=HhBu-2donSsuogabkfP03v1YF26Q7_BgvgA@mail.gmail.com/
Fixes: 94246930 ("i2c: i801: Create iTCO device on newer Intel PCHs")
[wsa: complete fix needs all of http://patchwork.ozlabs.org/project/linux-i2c/list/?series=160959&state=*]
Reported-by: Martin Volf <martin.volf.42@gmail.com>
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>