topology/sysfs: provide drawer id and siblings attributes

The s390 cpu topology gained another hierarchy level. The top level is
now called drawer and contains several books. A book used to be the
top level.

In order to expose the cpu topology to user space allow to create new
sysfs attributes dependent on CONFIG_SCHED_DRAWER which an
architecture may define and select.

These additional attributes will be available:

/sys/devices/system/cpu/cpuX/topology/drawer_id
/sys/devices/system/cpu/cpuX/topology/drawer_siblings
/sys/devices/system/cpu/cpuX/topology/drawer_siblings_list

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

1 files changed, 32 insertions, 8 deletions

diff --git a/Documentation/cputopology.txt b/Documentation/cputopology.txt
index 12b1b25b4da9..f722f227a73b 100644
--- a/Documentation/cputopology.txt
+++ b/Documentation/cputopology.txt
@@ -20,48 +20,70 @@ to /proc/cpuinfo output of some architectures:
 	identifier (rather than the kernel's).	The actual value is
 	architecture and platform dependent.
 
-4) /sys/devices/system/cpu/cpuX/topology/thread_siblings:
+4) /sys/devices/system/cpu/cpuX/topology/drawer_id:
+
+	the drawer ID of cpuX. Typically it is the hardware platform's
+	identifier (rather than the kernel's).	The actual value is
+	architecture and platform dependent.
+
+5) /sys/devices/system/cpu/cpuX/topology/thread_siblings:
 
 	internal kernel map of cpuX's hardware threads within the same
 	core as cpuX.
 
-5) /sys/devices/system/cpu/cpuX/topology/thread_siblings_list:
+6) /sys/devices/system/cpu/cpuX/topology/thread_siblings_list:
 
 	human-readable list of cpuX's hardware threads within the same
 	core as cpuX.
 
-6) /sys/devices/system/cpu/cpuX/topology/core_siblings:
+7) /sys/devices/system/cpu/cpuX/topology/core_siblings:
 
 	internal kernel map of cpuX's hardware threads within the same
 	physical_package_id.
 
-7) /sys/devices/system/cpu/cpuX/topology/core_siblings_list:
+8) /sys/devices/system/cpu/cpuX/topology/core_siblings_list:
 
 	human-readable list of cpuX's hardware threads within the same
 	physical_package_id.
 
-8) /sys/devices/system/cpu/cpuX/topology/book_siblings:
+9) /sys/devices/system/cpu/cpuX/topology/book_siblings:
 
 	internal kernel map of cpuX's hardware threads within the same
 	book_id.
 
-9) /sys/devices/system/cpu/cpuX/topology/book_siblings_list:
+10) /sys/devices/system/cpu/cpuX/topology/book_siblings_list:
 
 	human-readable list of cpuX's hardware threads within the same
 	book_id.
 
+11) /sys/devices/system/cpu/cpuX/topology/drawer_siblings:
+
+	internal kernel map of cpuX's hardware threads within the same
+	drawer_id.
+
+12) /sys/devices/system/cpu/cpuX/topology/drawer_siblings_list:
+
+	human-readable list of cpuX's hardware threads within the same
+	drawer_id.
+
 To implement it in an architecture-neutral way, a new source file,
-drivers/base/topology.c, is to export the 6 or 9 attributes. The three book
-related sysfs files will only be created if CONFIG_SCHED_BOOK is selected.
+drivers/base/topology.c, is to export the 6 to 12 attributes. The book
+and drawer related sysfs files will only be created if CONFIG_SCHED_BOOK
+and CONFIG_SCHED_DRAWER are selected.
+
+CONFIG_SCHED_BOOK and CONFIG_DRAWER are currently only used on s390, where
+they reflect the cpu and cache hierarchy.
 
 For an architecture to support this feature, it must define some of
 these macros in include/asm-XXX/topology.h:
 #define topology_physical_package_id(cpu)
 #define topology_core_id(cpu)
 #define topology_book_id(cpu)
+#define topology_drawer_id(cpu)
 #define topology_sibling_cpumask(cpu)
 #define topology_core_cpumask(cpu)
 #define topology_book_cpumask(cpu)
+#define topology_drawer_cpumask(cpu)
 
 The type of **_id macros is int.
 The type of **_cpumask macros is (const) struct cpumask *. The latter
@@ -78,6 +100,8 @@ not defined by include/asm-XXX/topology.h:
 
 For architectures that don't support books (CONFIG_SCHED_BOOK) there are no
 default definitions for topology_book_id() and topology_book_cpumask().
+For architectures that don't support drawes (CONFIG_SCHED_DRAWER) there are
+no default definitions for topology_drawer_id() and topology_drawer_cpumask().
 
 Additionally, CPU topology information is provided under
 /sys/devices/system/cpu and includes these files.  The internal