[PATCH v3 0/4] pseries-wdt: initial support for H_WATCHDOG-based watchdog timers

[Scott Cheloha <cheloha@linux.ibm.com>]

PAPR v2.12 defines a new hypercall, H_WATCHDOG.  This patch series
adds support for this hypercall to powerpc/pseries kernels and
introduces a new watchdog driver, "pseries-wdt", for the virtual
timers exposed by the hypercall.

This series is preceded by the following:

RFC v1: https://lore.kernel.org/linux-watchdog/20220413165104.179144-1-cheloha@linux.ibm.com/
RFC v2: https://lore.kernel.org/linux-watchdog/20220509174357.5448-1-cheloha@linux.ibm.com/
PATCH v1: https://lore.kernel.org/linux-watchdog/20220520183552.33426-1-cheloha@linux.ibm.com/
PATCH v2: https://lore.kernel.org/linux-watchdog/20220602175353.68942-1-cheloha@linux.ibm.com/

Changes of note from PATCH v2:

- Don't keep a pointer to the platform device at registration
  time.  We don't use the pointer for anything and we cannot
  hotplug the "device".

- Drop the GETFIELD() and SETFIELD() macros: Michael Ellerman really
  doesn't like them.  Use plain integer constants and custom bitfield
  extraction macros for the capability output instead.

  (After making the change I can see the upside to plain constants.)

- Actually use PSERIES_WDTQ_MAX_NUMBER(): check that the hypervisor
  gave us at least one timer to work with.

- Use MSEC_PER_SEC in a few places instead of the literal 1000 to
  show the reader what we're doing.

- Use "reverse xmas tree" sorting for automatic variable declarations.

- Note where the max_timeout of (UINT_MAX / 1000) comes from.

- Nix email addresses from the MODULE_AUTHOR() macros, they tend to
  rot.