[PATCH RFC 4/5] powerpc:numa Add helper functions to maintain chipid to nid mapping

[Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com>]

Create arrays that maps serial nids and sparse chipids.

Note: My original idea had only two arrays of chipid to nid map. Final
code is inspired by driver/acpi/numa.c that maps a proximity node with
a logical node by Takayoshi Kochi <t-kochi@bq.jp.nec.com>, and thus
uses an additional chipid_map nodemask. The mask helps in first unused
nid easily by knowing first unset bit in the mask.

No change in functionality.

Signed-off-by: Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com>
---
 arch/powerpc/mm/numa.c | 48 +++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 47 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/mm/numa.c b/arch/powerpc/mm/numa.c
index dd2073b..f015cad 100644
--- a/arch/powerpc/mm/numa.c
+++ b/arch/powerpc/mm/numa.c
@@ -63,6 +63,11 @@ static int form1_affinity;
 static int distance_ref_points_depth;
 static const __be32 *distance_ref_points;
 static int distance_lookup_table[MAX_NUMNODES][MAX_DISTANCE_REF_POINTS];
+static nodemask_t chipid_map = NODE_MASK_NONE;
+static int chipid_to_nid_map[MAX_NUMNODES]
+				= { [0 ... MAX_NUMNODES - 1] = NUMA_NO_NODE };
+static int nid_to_chipid_map[MAX_NUMNODES]
+				= { [0 ... MAX_NUMNODES - 1] = NUMA_NO_NODE };
 
 /*
  * Allocate node_to_cpumask_map based on number of available nodes
@@ -133,6 +138,48 @@ static int __init fake_numa_create_new_node(unsigned long end_pfn,
 	return 0;
 }
 
+int chipid_to_nid(int chipid)
+{
+	if (chipid < 0)
+		return NUMA_NO_NODE;
+	return chipid_to_nid_map[chipid];
+}
+
+int nid_to_chipid(int nid)
+{
+	if (nid < 0)
+		return NUMA_NO_NODE;
+	return nid_to_chipid_map[nid];
+}
+
+static void __map_chipid_to_nid(int chipid, int nid)
+{
+	if (chipid_to_nid_map[chipid] == NUMA_NO_NODE
+	     || nid < chipid_to_nid_map[chipid])
+		chipid_to_nid_map[chipid] = nid;
+	if (nid_to_chipid_map[nid] == NUMA_NO_NODE
+	    || chipid < nid_to_chipid_map[nid])
+		nid_to_chipid_map[nid] = chipid;
+}
+
+int map_chipid_to_nid(int chipid)
+{
+	int nid;
+
+	if (chipid < 0 || chipid >= MAX_NUMNODES)
+		return NUMA_NO_NODE;
+
+	nid = chipid_to_nid_map[chipid];
+	if (nid == NUMA_NO_NODE) {
+		if (nodes_weight(chipid_map) >= MAX_NUMNODES)
+			return NUMA_NO_NODE;
+		nid = first_unset_node(chipid_map);
+		__map_chipid_to_nid(chipid, nid);
+		node_set(nid, chipid_map);
+	}
+	return nid;
+}
+
 int numa_cpu_lookup(int cpu)
 {
 	return numa_cpu_lookup_table[cpu];
@@ -264,7 +311,6 @@ out:
 	return chipid;
 }
 
-
  /* Return the nid from associativity */
 static int associativity_to_nid(const __be32 *associativity)
 {
-- 
1.7.11.7