[PATCH] Export cpu topology in sysfs

The patch implements cpu topology exportation by sysfs.

Items (attributes) are similar to /proc/cpuinfo.

1) /sys/devices/system/cpu/cpuX/topology/physical_package_id:
	represent the physical package id of  cpu X;
2) /sys/devices/system/cpu/cpuX/topology/core_id:
	represent the cpu core id to cpu X;
3) /sys/devices/system/cpu/cpuX/topology/thread_siblings:
	represent the thread siblings to cpu X in the same core;
4) /sys/devices/system/cpu/cpuX/topology/core_siblings:
	represent the thread siblings to cpu X in the same physical package;

To implement it in an architecture-neutral way, a new source file,
driver/base/topology.c, is to export the 5 attributes.

If one architecture wants to support this feature, it just needs to
implement 4 defines, typically in file include/asm-XXX/topology.h.
The 4 defines are:
#define topology_physical_package_id(cpu)
#define topology_core_id(cpu)
#define topology_thread_siblings(cpu)
#define topology_core_siblings(cpu)

The type of **_id is int.
The type of siblings is cpumask_t.

To be consistent on all architectures, the 4 attributes should have
deafult values if their values are unavailable. Below is the rule.

1) physical_package_id: If cpu has no physical package id, -1 is the
default value.

2) core_id: If cpu doesn't support multi-core, its core id is 0.

3) thread_siblings: Just include itself, if the cpu doesn't support
HT/multi-thread.

4) core_siblings: Just include itself, if the cpu doesn't support
multi-core and HT/Multi-thread.

So be careful when declaring the 4 defines in include/asm-XXX/topology.h.

If an attribute isn't defined on an architecture, it won't be exported.

Thank Nathan, Greg, Andi, Paul and Venki.

The patch provides defines for i386/x86_64/ia64.

Signed-off-by: Zhang, Yanmin <yanmin.zhang@intel.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: Greg KH <greg@kroah.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

7 files changed, 225 insertions, 8 deletions

diff --git a/Documentation/cputopology.txt b/Documentation/cputopology.txt
new file mode 100644
index 000000000000..ff280e2e1613
--- /dev/null
+++ b/Documentation/cputopology.txt
@@ -0,0 +1,41 @@
+
+Export cpu topology info by sysfs. Items (attributes) are similar
+to /proc/cpuinfo.
+
+1) /sys/devices/system/cpu/cpuX/topology/physical_package_id:
+represent the physical package id of  cpu X;
+2) /sys/devices/system/cpu/cpuX/topology/core_id:
+represent the cpu core id to cpu X;
+3) /sys/devices/system/cpu/cpuX/topology/thread_siblings:
+represent the thread siblings to cpu X in the same core;
+4) /sys/devices/system/cpu/cpuX/topology/core_siblings:
+represent the thread siblings to cpu X in the same physical package;
+
+To implement it in an architecture-neutral way, a new source file,
+driver/base/topology.c, is to export the 5 attributes.
+
+If one architecture wants to support this feature, it just needs to
+implement 4 defines, typically in file include/asm-XXX/topology.h.
+The 4 defines are:
+#define topology_physical_package_id(cpu)
+#define topology_core_id(cpu)
+#define topology_thread_siblings(cpu)
+#define topology_core_siblings(cpu)
+
+The type of **_id is int.
+The type of siblings is cpumask_t.
+
+To be consistent on all architectures, the 4 attributes should have
+deafult values if their values are unavailable. Below is the rule.
+1) physical_package_id: If cpu has no physical package id, -1 is the
+default value.
+2) core_id: If cpu doesn't support multi-core, its core id is 0.
+3) thread_siblings: Just include itself, if the cpu doesn't support
+HT/multi-thread.
+4) core_siblings: Just include itself, if the cpu doesn't support
+multi-core and HT/Multi-thread.
+
+So be careful when declaring the 4 defines in include/asm-XXX/topology.h.
+
+If an attribute isn't defined on an architecture, it won't be exported.
+
diff --git a/arch/ia64/kernel/topology.c b/arch/ia64/kernel/topology.c
index 706b7734e191..6e5eea19fa67 100644
--- a/arch/ia64/kernel/topology.c
+++ b/arch/ia64/kernel/topology.c
@@ -71,31 +71,33 @@ static int __init topology_init(void)
         int i, err = 0;
 
 #ifdef CONFIG_NUMA
-        sysfs_nodes = kmalloc(sizeof(struct node) * MAX_NUMNODES, GFP_KERNEL);
+        sysfs_nodes = kzalloc(sizeof(struct node) * MAX_NUMNODES, GFP_KERNEL);
         if (!sysfs_nodes) {
                 err = -ENOMEM;
                 goto out;
         }
-        memset(sysfs_nodes, 0, sizeof(struct node) * MAX_NUMNODES);
 
-        /* MCD - Do we want to register all ONLINE nodes, or all POSSIBLE nodes? */
-        for_each_online_node(i)
+        /*
+         * MCD - Do we want to register all ONLINE nodes, or all POSSIBLE nodes?
+         */
+        for_each_online_node(i) {
                 if ((err = register_node(&sysfs_nodes[i], i, 0)))
                         goto out;
+        }
 #endif
 
-        sysfs_cpus = kmalloc(sizeof(struct ia64_cpu) * NR_CPUS, GFP_KERNEL);
+        sysfs_cpus = kzalloc(sizeof(struct ia64_cpu) * NR_CPUS, GFP_KERNEL);
         if (!sysfs_cpus) {
                 err = -ENOMEM;
                 goto out;
         }
-        memset(sysfs_cpus, 0, sizeof(struct ia64_cpu) * NR_CPUS);
 
-        for_each_present_cpu(i)
+        for_each_present_cpu(i) {
                 if((err = arch_register_cpu(i)))
                         goto out;
+        }
 out:
         return err;
 }
 
-__initcall(topology_init);
+subsys_initcall(topology_init);
diff --git a/drivers/base/Makefile b/drivers/base/Makefile
index f12898d53078..e99471d3232b 100644
--- a/drivers/base/Makefile
+++ b/drivers/base/Makefile
@@ -8,6 +8,7 @@ obj-y			+= power/
 obj-$(CONFIG_FW_LOADER) += firmware_class.o
 obj-$(CONFIG_NUMA)      += node.o
 obj-$(CONFIG_MEMORY_HOTPLUG) += memory.o
+obj-$(CONFIG_SMP)       += topology.o
 
 ifeq ($(CONFIG_DEBUG_DRIVER),y)
 EXTRA_CFLAGS += -DDEBUG
diff --git a/drivers/base/topology.c b/drivers/base/topology.c
new file mode 100644
index 000000000000..915810f6237e
--- /dev/null
+++ b/drivers/base/topology.c
@@ -0,0 +1,148 @@
+/*
+ * driver/base/topology.c - Populate sysfs with cpu topology information
+ *
+ * Written by: Zhang Yanmin, Intel Corporation
+ *
+ * Copyright (C) 2006, Intel Corp.
+ *
+ * All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
+ * NON INFRINGEMENT.  See the GNU General Public License for more
+ * details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ *
+ */
+#include <linux/sysdev.h>
+#include <linux/init.h>
+#include <linux/mm.h>
+#include <linux/cpu.h>
+#include <linux/module.h>
+#include <linux/topology.h>
+
+#define define_one_ro(_name)            \
+static SYSDEV_ATTR(_name, 0444, show_##_name, NULL)
+
+#define define_id_show_func(name)                               \
+static ssize_t show_##name(struct sys_device *dev, char *buf)   \
+{                                                               \
+        unsigned int cpu = dev->id;                             \
+        return sprintf(buf, "%d\n", topology_##name(cpu));      \
+}
+
+#define define_siblings_show_func(name)                                 \
+static ssize_t show_##name(struct sys_device *dev, char *buf)           \
+{                                                                       \
+        ssize_t len = -1;                                               \
+        unsigned int cpu = dev->id;                                     \
+        len = cpumask_scnprintf(buf, NR_CPUS+1, topology_##name(cpu));  \
+        return (len + sprintf(buf + len, "\n"));                        \
+}
+
+#ifdef  topology_physical_package_id
+define_id_show_func(physical_package_id);
+define_one_ro(physical_package_id);
+#define ref_physical_package_id_attr    &attr_physical_package_id.attr,
+#else
+#define ref_physical_package_id_attr
+#endif
+
+#ifdef topology_core_id
+define_id_show_func(core_id);
+define_one_ro(core_id);
+#define ref_core_id_attr                &attr_core_id.attr,
+#else
+#define ref_core_id_attr
+#endif
+
+#ifdef topology_thread_siblings
+define_siblings_show_func(thread_siblings);
+define_one_ro(thread_siblings);
+#define ref_thread_siblings_attr        &attr_thread_siblings.attr,
+#else
+#define ref_thread_siblings_attr
+#endif
+
+#ifdef topology_core_siblings
+define_siblings_show_func(core_siblings);
+define_one_ro(core_siblings);
+#define ref_core_siblings_attr          &attr_core_siblings.attr,
+#else
+#define ref_core_siblings_attr
+#endif
+
+static struct attribute *default_attrs[] = {
+        ref_physical_package_id_attr
+        ref_core_id_attr
+        ref_thread_siblings_attr
+        ref_core_siblings_attr
+        NULL
+};
+
+static struct attribute_group topology_attr_group = {
+        .attrs = default_attrs,
+        .name = "topology"
+};
+
+/* Add/Remove cpu_topology interface for CPU device */
+static int __cpuinit topology_add_dev(struct sys_device * sys_dev)
+{
+        sysfs_create_group(&sys_dev->kobj, &topology_attr_group);
+        return 0;
+}
+
+static int __cpuinit topology_remove_dev(struct sys_device * sys_dev)
+{
+        sysfs_remove_group(&sys_dev->kobj, &topology_attr_group);
+        return 0;
+}
+
+static int __cpuinit topology_cpu_callback(struct notifier_block *nfb,
+                unsigned long action, void *hcpu)
+{
+        unsigned int cpu = (unsigned long)hcpu;
+        struct sys_device *sys_dev;
+
+        sys_dev = get_cpu_sysdev(cpu);
+        switch (action) {
+        case CPU_ONLINE:
+                topology_add_dev(sys_dev);
+                break;
+        case CPU_DEAD:
+                topology_remove_dev(sys_dev);
+                break;
+        }
+        return NOTIFY_OK;
+}
+
+static struct notifier_block topology_cpu_notifier =
+{
+        .notifier_call = topology_cpu_callback,
+};
+
+static int __cpuinit topology_sysfs_init(void)
+{
+        int i;
+
+        for_each_online_cpu(i) {
+                topology_cpu_callback(&topology_cpu_notifier, CPU_ONLINE,
+                                (void *)(long)i);
+        }
+
+        register_cpu_notifier(&topology_cpu_notifier);
+
+        return 0;
+}
+
+device_initcall(topology_sysfs_init);
+
diff --git a/include/asm-i386/topology.h b/include/asm-i386/topology.h
index d7e19eb344b7..af503a122b23 100644
--- a/include/asm-i386/topology.h
+++ b/include/asm-i386/topology.h
@@ -27,6 +27,15 @@
 #ifndef _ASM_I386_TOPOLOGY_H
 #define _ASM_I386_TOPOLOGY_H
 
+#ifdef CONFIG_SMP
+#define topology_physical_package_id(cpu)                               \
+        (phys_proc_id[cpu] == BAD_APICID ? -1 : phys_proc_id[cpu])
+#define topology_core_id(cpu)                                           \
+        (cpu_core_id[cpu] == BAD_APICID ? 0 : cpu_core_id[cpu])
+#define topology_core_siblings(cpu)             (cpu_core_map[cpu])
+#define topology_thread_siblings(cpu)           (cpu_sibling_map[cpu])
+#endif
+
 #ifdef CONFIG_NUMA
 
 #include <asm/mpspec.h>
diff --git a/include/asm-ia64/topology.h b/include/asm-ia64/topology.h
index 412ef8e493a8..3ee19dfa46df 100644
--- a/include/asm-ia64/topology.h
+++ b/include/asm-ia64/topology.h
@@ -102,6 +102,13 @@ void build_cpu_to_node_map(void);
 
 #endif /* CONFIG_NUMA */
 
+#ifdef CONFIG_SMP
+#define topology_physical_package_id(cpu)       (cpu_data(cpu)->socket_id)
+#define topology_core_id(cpu)                   (cpu_data(cpu)->core_id)
+#define topology_core_siblings(cpu)             (cpu_core_map[cpu])
+#define topology_thread_siblings(cpu)           (cpu_sibling_map[cpu])
+#endif
+
 #include <asm-generic/topology.h>
 
 #endif /* _ASM_IA64_TOPOLOGY_H */
diff --git a/include/asm-x86_64/topology.h b/include/asm-x86_64/topology.h
index 2fa7f27381b4..c642f5d9882d 100644
--- a/include/asm-x86_64/topology.h
+++ b/include/asm-x86_64/topology.h
@@ -57,6 +57,15 @@ extern int __node_distance(int, int);
 
 #endif
 
+#ifdef CONFIG_SMP
+#define topology_physical_package_id(cpu)                               \
+        (phys_proc_id[cpu] == BAD_APICID ? -1 : phys_proc_id[cpu])
+#define topology_core_id(cpu)                                           \
+        (cpu_core_id[cpu] == BAD_APICID ? 0 : cpu_core_id[cpu])
+#define topology_core_siblings(cpu)             (cpu_core_map[cpu])
+#define topology_thread_siblings(cpu)           (cpu_sibling_map[cpu])
+#endif
+
 #include <asm-generic/topology.h>
 
 #endif