[PATCH v3] kernel.h: add comments for system_states

[Randy Dunlap]

Provide some basic comments about the system_states and what they imply.
Also convert the comments to kernel-doc format.

Signed-off-by: Randy Dunlap <rdunlap@xxxxxxxxxxxxx>
Cc: "Rafael J. Wysocki" <rafael@xxxxxxxxxx>
Cc: Pavel Machek <pavel@xxxxxx>
Cc: Len Brown <len.brown@xxxxxxxxx>
Cc: linux-pm@xxxxxxxxxxxxxxx
Cc: "James E.J. Bottomley" <James.Bottomley@xxxxxxxxxxxxxxxxxxxxx>
Acked-by: Rafael J. Wysocki <rafael@xxxxxxxxxx>
---
v2: add Rafael's Ack.
v3: add Andrew for merging.

 include/linux/kernel.h |   14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

--- linux-next-20250814.orig/include/linux/kernel.h
+++ linux-next-20250814/include/linux/kernel.h
@@ -164,9 +164,19 @@ extern int root_mountflags;
 
 extern bool early_boot_irqs_disabled;
 
-/*
- * Values used for system_state. Ordering of the states must not be changed
+/**
+ * enum system_states - Values used for system_state.
+ * Ordering of the states must not be changed
  * as code checks for <, <=, >, >= STATE.
+ *
+ * @SYSTEM_BOOTING:	%0, no init needed
+ * @SYSTEM_SCHEDULING:	system is ready for scheduling; OK to use RCU
+ * @SYSTEM_FREEING_INITMEM: system is freeing all of initmem; almost running
+ * @SYSTEM_RUNNING:	system is up and running
+ * @SYSTEM_HALT:	system entered clean system halt state
+ * @SYSTEM_POWER_OFF:	system entered shutdown/clean power off state
+ * @SYSTEM_RESTART:	system entered emergency power off or normal restart
+ * @SYSTEM_SUSPEND:	system entered suspend or hibernate state
  */
 extern enum system_states {
 	SYSTEM_BOOTING,