Documentation: irqdomain: Update it

The irqdomain documentaion became obsolete over time. Update and extend
it a bit with respect to the current code and HW.

Most notably the doubled documentation of irq_domain (from .rst and .h)
was unified and let only in .rst. A reference link was added to .h.

Furthermore:
 * Add some 'struct' keywords, so that the respective structs are
   hyperlinked
 * :c:member: use where appropriate to mark a member of a struct
 * Rephrase some wording to improve readability/understanding

Signed-off-by: Jiri Slaby (SUSE) <jirislaby@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/all/20250319092951.37667-57-jirislaby@kernel.org

1 files changed, 2 insertions, 24 deletions

diff --git a/include/linux/irqdomain.h b/include/linux/irqdomain.h
index a70e2ba0b91f..1a1786dc19d2 100644
--- a/include/linux/irqdomain.h
+++ b/include/linux/irqdomain.h
@@ -1,30 +1,8 @@
 /* SPDX-License-Identifier: GPL-2.0 */
 /*
- * irq_domain - IRQ translation domains
+ * irq_domain - IRQ Translation Domains
  *
- * Translation infrastructure between hw and linux irq numbers.  This is
- * helpful for interrupt controllers to implement mapping between hardware
- * irq numbers and the Linux irq number space.
- *
- * irq_domains also have hooks for translating device tree or other
- * firmware interrupt representations into a hardware irq number that
- * can be mapped back to a Linux irq number without any extra platform
- * support code.
- *
- * Interrupt controller "domain" data structure. This could be defined as a
- * irq domain controller. That is, it handles the mapping between hardware
- * and virtual interrupt numbers for a given interrupt domain. The domain
- * structure is generally created by the PIC code for a given PIC instance
- * (though a domain can cover more than one PIC if they have a flat number
- * model). It's the domain callbacks that are responsible for setting the
- * irq_chip on a given irq_desc after it's been mapped.
- *
- * The host code and data structures use a fwnode_handle pointer to
- * identify the domain. In some cases, and in order to preserve source
- * code compatibility, this fwnode pointer is "upgraded" to a DT
- * device_node. For those firmware infrastructures that do not provide
- * a unique identifier for an interrupt controller, the irq_domain
- * code offers a fwnode allocator.
+ * See Documentation/core-api/irq/irq-domain.rst for the details.
  */
 
 #ifndef _LINUX_IRQDOMAIN_H