powerpc: Use ibm, chip-id property to compute cpu_core_mask if available

Some systems have an ibm,chip-id property in the cpu nodes in the
device tree.  On these systems, we now use that to compute the
cpu_core_mask (i.e. the set of core siblings) rather than looking
at cache properties.

Signed-off-by: Paul Mackerras <paulus@samba.org>
Tested-by: Vasant Hegde <hegdevasant@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

diff --git a/arch/powerpc/kernel/smp.c b/arch/powerpc/kernel/smp.c
index 0cc69d5deac9bc022d1d98721e589a9973b95bca..009900dd8f2525f050a179e3983248860cec1682 100644 (file)
--- a/arch/powerpc/kernel/smp.c
+++ b/arch/powerpc/kernel/smp.c
@@ -609,6 +609,33 @@ int cpu_first_thread_of_core(int core)
 }
 EXPORT_SYMBOL_GPL(cpu_first_thread_of_core);
 
+static void traverse_siblings_chip_id(int cpu, bool add, int chipid)
+{
+       const struct cpumask *mask;
+       struct device_node *np;
+       int i, plen;
+       const __be32 *prop;
+
+       mask = add ? cpu_online_mask : cpu_present_mask;
+       for_each_cpu(i, mask) {
+               np = of_get_cpu_node(i, NULL);
+               if (!np)
+                       continue;
+               prop = of_get_property(np, "ibm,chip-id", &plen);
+               if (prop && plen == sizeof(int) &&
+                   of_read_number(prop, 1) == chipid) {
+                       if (add) {
+                               cpumask_set_cpu(cpu, cpu_core_mask(i));
+                               cpumask_set_cpu(i, cpu_core_mask(cpu));
+                       } else {
+                               cpumask_clear_cpu(cpu, cpu_core_mask(i));
+                               cpumask_clear_cpu(i, cpu_core_mask(cpu));
+                       }
+               }
+               of_node_put(np);
+       }
+}
+
 /* Must be called when no change can occur to cpu_present_mask,
  * i.e. during cpu online or offline.
  */
@@ -633,14 +660,29 @@ static struct device_node *cpu_to_l2cache(int cpu)
 
 static void traverse_core_siblings(int cpu, bool add)
 {
-       struct device_node *l2_cache;
+       struct device_node *l2_cache, *np;
        const struct cpumask *mask;
-       int i;
+       int i, chip, plen;
+       const __be32 *prop;
+
+       /* First see if we have ibm,chip-id properties in cpu nodes */
+       np = of_get_cpu_node(cpu, NULL);
+       if (np) {
+               chip = -1;
+               prop = of_get_property(np, "ibm,chip-id", &plen);
+               if (prop && plen == sizeof(int))
+                       chip = of_read_number(prop, 1);
+               of_node_put(np);
+               if (chip >= 0) {
+                       traverse_siblings_chip_id(cpu, add, chip);
+                       return;
+               }
+       }
 
        l2_cache = cpu_to_l2cache(cpu);
        mask = add ? cpu_online_mask : cpu_present_mask;
        for_each_cpu(i, mask) {
-               struct device_node *np = cpu_to_l2cache(i);
+               np = cpu_to_l2cache(i);
                if (!np)
                        continue;
                if (np == l2_cache) {