The core infrastructure has everything in place to switch ICU to per
device MSI domains and avoid the convoluted construct of the existing
platform-MSI layering violation.

The new infrastructure provides a wired interrupt specific interface in the
MSI core which converts the 'hardware interrupt number + trigger type'
allocation which is required for wired interrupts in the regular irqdomain
code to a normal MSI allocation.

The hardware interrupt number and the trigger type are stored in the MSI
descriptor device cookie by the core code so the ICU specific code can
retrieve them.

The new per device domain is only instantiated when the irqdomain which is
associated to the ICU device provides MSI parent functionality. Up to
that point it invokes the existing code. Once the parent is converted the
code for the current platform-MSI mechanism is removed.

The new domain shares the interrupt chip callbacks and the translation
function. The only new functionality aside of filling out the
msi_domain_templates is a domain specific set_desc() callback, which will go
away once all platform-MSI code has been converted.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Anna-Maria Behnsen <anna-maria@linutronix.de>
Signed-off-by: Shivamurthy Shastri <shivamurthy.shastri@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20240623142235.635015886@linutronix.de