[RFC patch] powerpc: Add topology_ready to machdep calls

Add a new member topology_ready to the powerpc machdep_calls
structure.

The NUMA hot plug memory routines require the NUMA node to have
been registered via register_one_node() prior to adding memory
to the node.  The powerpc arch registers NUMA nodes during
startup in its topology_init() routine.

Currently, there is no mechanism for the platform code to know
when the nodes have been registered, and hence, when it is safe
to add hot plug memory.

Signed-off-by: Geoff Levand <redacted>
---
 arch/powerpc/include/asm/machdep.h |    1 +
 arch/powerpc/kernel/sysfs.c        |    3 +++
 2 files changed, 4 insertions(+)

--- a/arch/powerpc/include/asm/machdep.h
+++ b/arch/powerpc/include/asm/machdep.h

@@ -106,6 +106,7 @@ struct machdep_calls {
 	void		(*setup_arch)(void); /* Optional, may be NULL */
 	void		(*init_early)(void);
 	/* Optional, may be NULL. */
+	void		(*topology_ready)(void); /* Optional, may be NULL */
 	void		(*show_cpuinfo)(struct seq_file *m);
 	void		(*show_percpuinfo)(struct seq_file *m, int i);
 
--- a/arch/powerpc/kernel/sysfs.c
+++ b/arch/powerpc/kernel/sysfs.c

@@ -647,6 +647,9 @@ static int __init topology_init(void)
 			register_cpu_online(cpu);
 	}
 
+	if (ppc_md.topology_ready)
+		ppc_md.topology_ready();
+
 	return 0;
 }
 subsys_initcall(topology_init);