[PATCH 5/6] powerpc: Implement DISCONTIGMEM and allow selection on PPC32

[Jonathan Neuschäfer]

The implementation of pfn_to_nid and pfn_valid in mmzone.h is based on
arch/metag's implementation.

Signed-off-by: Jonathan Neuschäfer <j.neuschae...@gmx.net>
---

NOTE: Checking NODE_DATA(nid) in pfn_to_nid appears to be uncommon.
Running up to MAX_NUMNODES instead of checking NODE_DATA(nid) would
require the node_data array to be filled with valid pointers.
---
 arch/powerpc/Kconfig              |  5 ++++-
 arch/powerpc/include/asm/mmzone.h | 21 +++++++++++++++++++++
 arch/powerpc/mm/numa.c            |  7 +++++++
 3 files changed, 32 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 73ce5dd07642..c2633b7b8ed9 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -639,7 +639,6 @@ config HAVE_MEMORYLESS_NODES
 
 config ARCH_SELECT_MEMORY_MODEL
        def_bool y
-       depends on PPC64
 
 config ARCH_FLATMEM_ENABLE
        def_bool y
@@ -654,6 +653,10 @@ config ARCH_SPARSEMEM_DEFAULT
        def_bool y
        depends on PPC_BOOK3S_64
 
+config ARCH_DISCONTIGMEM_ENABLE
+       def_bool y
+       depends on PPC32
+
 config SYS_SUPPORTS_HUGETLBFS
        bool
 
diff --git a/arch/powerpc/include/asm/mmzone.h 
b/arch/powerpc/include/asm/mmzone.h
index 91c69ff53a8a..1684a5c98d23 100644
--- a/arch/powerpc/include/asm/mmzone.h
+++ b/arch/powerpc/include/asm/mmzone.h
@@ -26,6 +26,27 @@ extern struct pglist_data *node_data[];
  */
 #define NODE_DATA(nid)         (node_data[nid])
 
+static inline int pfn_to_nid(unsigned long pfn)
+{
+       int nid;
+
+       for (nid = 0; nid < MAX_NUMNODES && NODE_DATA(nid); nid++)
+               if (pfn >= node_start_pfn(nid) && pfn <= node_end_pfn(nid))
+                       return nid;
+
+       return -1;
+}
+
+static inline int pfn_valid(int pfn)
+{
+       int nid = pfn_to_nid(pfn);
+
+       if (nid >= 0)
+               return pfn < node_end_pfn(nid);
+
+       return 0;
+}
+
 /*
  * Following are specific to this numa platform.
  */
diff --git a/arch/powerpc/mm/numa.c b/arch/powerpc/mm/numa.c
index dfe279529463..ec47f1081509 100644
--- a/arch/powerpc/mm/numa.c
+++ b/arch/powerpc/mm/numa.c
@@ -744,6 +744,13 @@ static void __init setup_nonnuma(void)
                                  PFN_PHYS(end_pfn - start_pfn),
                                  &memblock.memory, nid);
                node_set_online(nid);
+
+               /*
+                * On DISCONTIGMEM systems, place different memory blocks into
+                * different nodes.
+                */
+               if (IS_ENABLED(CONFIG_DISCONTIGMEM) && nid < MAX_NUMNODES - 1)
+                       nid++;
        }
 }
 
-- 
2.16.1