powerpc: Cleanup APIs for cpu/thread/core mappings

These APIs take logical cpu number as input
Change cpu_first_thread_in_core() to cpu_first_thread_sibling()
Change cpu_last_thread_in_core() to cpu_last_thread_sibling()

These APIs convert core number (index) to logical cpu/thread numbers
Add cpu_first_thread_of_core(int core)
Changed cpu_thread_to_core() to cpu_core_index_of_thread(int cpu)

The goal is to make 'threads_per_core' accessible to the
pseries_energy module.  Instead of making an API to read
threads_per_core, this is a higher level wrapper function to
convert from logical cpu number to core number.

The current APIs cpu_first_thread_in_core() and
cpu_last_thread_in_core() returns logical CPU number while
cpu_thread_to_core() returns core number or index which is
not a logical CPU number.  The new APIs are now clearly named to
distinguish 'core number' versus first and last 'logical cpu
number' in that core.

The new APIs cpu_{first,last}_thread_sibling() work on
logical cpu numbers.  While cpu_first_thread_of_core() and
cpu_core_index_of_thread() work on core index.

Example usage:  (4 threads per core system)

cpu_first_thread_sibling(5) = 4
cpu_last_thread_sibling(5) = 7
cpu_core_index_of_thread(5) = 1
cpu_first_thread_of_core(1) = 4

cpu_core_index_of_thread() is used in cpu_to_drc_index() in the
module and cpu_first_thread_of_core() is used in
drc_index_to_cpu() in the module.

Make API changes to few callers.  Export symbols for use in modules.

Signed-off-by: Vaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

1 files changed, 6 insertions, 6 deletions

diff --git a/arch/powerpc/mm/mmu_context_nohash.c b/arch/powerpc/mm/mmu_context_nohash.c
index 5ce99848d91e..c0aab52da3a5 100644
--- a/arch/powerpc/mm/mmu_context_nohash.c
+++ b/arch/powerpc/mm/mmu_context_nohash.c
@@ -111,8 +111,8 @@ static unsigned int steal_context_smp(unsigned int id)
                  * a core map instead but this will do for now.
                  */
                 for_each_cpu(cpu, mm_cpumask(mm)) {
-                        for (i = cpu_first_thread_in_core(cpu);
-                             i <= cpu_last_thread_in_core(cpu); i++)
+                        for (i = cpu_first_thread_sibling(cpu);
+                             i <= cpu_last_thread_sibling(cpu); i++)
                                 __set_bit(id, stale_map[i]);
                         cpu = i - 1;
                 }
@@ -264,14 +264,14 @@ void switch_mmu_context(struct mm_struct *prev, struct mm_struct *next)
          */
         if (test_bit(id, stale_map[cpu])) {
                 pr_hardcont(" | stale flush %d [%d..%d]",
-                            id, cpu_first_thread_in_core(cpu),
-                            cpu_last_thread_in_core(cpu));
+                            id, cpu_first_thread_sibling(cpu),
+                            cpu_last_thread_sibling(cpu));
 
                 local_flush_tlb_mm(next);
 
                 /* XXX This clear should ultimately be part of local_flush_tlb_mm */
-                for (i = cpu_first_thread_in_core(cpu);
-                     i <= cpu_last_thread_in_core(cpu); i++) {
+                for (i = cpu_first_thread_sibling(cpu);
+                     i <= cpu_last_thread_sibling(cpu); i++) {
                         __clear_bit(id, stale_map[i]);
                 }
         }