[S390] topology: get rid of ifdefs

Remove all ifdefs from topology code and also only compile it for the
CONFIG_SCHED_BOOK case. The new code selects SCHED_MC if SCHED_BOOK is
selected. SCHED_MC without SCHED_BOOK is not possible anymore.
Furthermore various sysfs attributes are not available anymore for the
!SCHED_BOOK case. In particular all attributes that correspond to
CPU polarization.
But since all real world kernels have SCHED_BOOK selected anyway this
doesn't matter too much.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

6 files changed, 176 insertions, 162 deletions

diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig
index 373679b3744a..6b35b41a09ca 100644
--- a/arch/s390/Kconfig
+++ b/arch/s390/Kconfig
@@ -191,18 +191,13 @@ config HOTPLUG_CPU
 	  Say N if you want to disable CPU hotplug.
 
 config SCHED_MC
-	def_bool y
-	prompt "Multi-core scheduler support"
-	depends on SMP
-	help
-	  Multi-core scheduler support improves the CPU scheduler's decision
-	  making when dealing with multi-core CPU chips at a cost of slightly
-	  increased overhead in some places.
+	def_bool n
 
 config SCHED_BOOK
 	def_bool y
 	prompt "Book scheduler support"
-	depends on SMP && SCHED_MC
+	depends on SMP
+	select SCHED_MC
 	help
 	  Book scheduler support improves the CPU scheduler's decision making
 	  when dealing with machines that have several books.
diff --git a/arch/s390/include/asm/smp.h b/arch/s390/include/asm/smp.h
index ab47a69fdf07..c32e9123b40c 100644
--- a/arch/s390/include/asm/smp.h
+++ b/arch/s390/include/asm/smp.h
@@ -23,7 +23,6 @@ extern void __cpu_die (unsigned int cpu);
 extern int __cpu_up (unsigned int cpu);
 
 extern struct mutex smp_cpu_state_mutex;
-extern int smp_cpu_polarization[];
 
 extern void arch_send_call_function_single_ipi(int cpu);
 extern void arch_send_call_function_ipi_mask(const struct cpumask *mask);
diff --git a/arch/s390/include/asm/topology.h b/arch/s390/include/asm/topology.h
index 005d77d8ae2a..7016dd7b6bc4 100644
--- a/arch/s390/include/asm/topology.h
+++ b/arch/s390/include/asm/topology.h
@@ -4,6 +4,10 @@
 #include <linux/cpumask.h>
 #include <asm/sysinfo.h>
 
+struct cpu;
+
+#ifdef CONFIG_SCHED_BOOK
+
 extern unsigned char cpu_core_id[NR_CPUS];
 extern cpumask_t cpu_core_map[NR_CPUS];
 
@@ -16,8 +20,6 @@ static inline const struct cpumask *cpu_coregroup_mask(int cpu)
 #define topology_core_cpumask(cpu)	(&cpu_core_map[cpu])
 #define mc_capable()			(1)
 
-#ifdef CONFIG_SCHED_BOOK
-
 extern unsigned char cpu_book_id[NR_CPUS];
 extern cpumask_t cpu_book_map[NR_CPUS];
 
@@ -29,19 +31,43 @@ static inline const struct cpumask *cpu_book_mask(int cpu)
 #define topology_book_id(cpu)		(cpu_book_id[cpu])
 #define topology_book_cpumask(cpu)	(&cpu_book_map[cpu])
 
-#endif /* CONFIG_SCHED_BOOK */
-
+int topology_cpu_init(struct cpu *);
 int topology_set_cpu_management(int fc);
 void topology_schedule_update(void);
 void store_topology(struct sysinfo_15_1_x *info);
 
-#define POLARIZATION_UNKNWN	(-1)
+#else /* CONFIG_SCHED_BOOK */
+
+static inline void topology_schedule_update(void) { }
+static inline int topology_cpu_init(struct cpu *cpu) { return 0; }
+
+#endif /* CONFIG_SCHED_BOOK */
+
+#define POLARIZATION_UNKNOWN	(-1)
 #define POLARIZATION_HRZ	(0)
 #define POLARIZATION_VL		(1)
 #define POLARIZATION_VM		(2)
 #define POLARIZATION_VH		(3)
 
-#ifdef CONFIG_SMP
+extern int cpu_polarization[];
+
+static inline void cpu_set_polarization(int cpu, int val)
+{
+#ifdef CONFIG_SCHED_BOOK
+	cpu_polarization[cpu] = val;
+#endif
+}
+
+static inline int cpu_read_polarization(int cpu)
+{
+#ifdef CONFIG_SCHED_BOOK
+	return cpu_polarization[cpu];
+#else
+	return POLARIZATION_HRZ;
+#endif
+}
+
+#ifdef CONFIG_SCHED_BOOK
 void s390_init_cpu_topology(void);
 #else
 static inline void s390_init_cpu_topology(void)
diff --git a/arch/s390/kernel/Makefile b/arch/s390/kernel/Makefile
index dd4f07640919..7d9ec924e7e7 100644
--- a/arch/s390/kernel/Makefile
+++ b/arch/s390/kernel/Makefile
@@ -32,7 +32,8 @@ extra-y				+= head.o init_task.o vmlinux.lds
 extra-y				+= $(if $(CONFIG_64BIT),head64.o,head31.o)
 
 obj-$(CONFIG_MODULES)		+= s390_ksyms.o module.o
-obj-$(CONFIG_SMP)		+= smp.o topology.o
+obj-$(CONFIG_SMP)		+= smp.o
+obj-$(CONFIG_SCHED_BOOK)	+= topology.o
 obj-$(CONFIG_SMP)		+= $(if $(CONFIG_64BIT),switch_cpu64.o, \
 							switch_cpu.o)
 obj-$(CONFIG_HIBERNATION)	+= suspend.o swsusp_asm64.o
diff --git a/arch/s390/kernel/smp.c b/arch/s390/kernel/smp.c
index 14d5211a185d..9cf01e455e50 100644
--- a/arch/s390/kernel/smp.c
+++ b/arch/s390/kernel/smp.c
@@ -69,9 +69,7 @@ enum s390_cpu_state {
 };
 
 DEFINE_MUTEX(smp_cpu_state_mutex);
-int smp_cpu_polarization[NR_CPUS];
 static int smp_cpu_state[NR_CPUS];
-static int cpu_management;
 
 static DEFINE_PER_CPU(struct cpu, cpu_devices);
 
@@ -369,7 +367,7 @@ static int smp_rescan_cpus_sigp(cpumask_t avail)
 		if (cpu_known(cpu_id))
 			continue;
 		__cpu_logical_map[logical_cpu] = cpu_id;
-		smp_cpu_polarization[logical_cpu] = POLARIZATION_UNKNWN;
+		cpu_set_polarization(logical_cpu, POLARIZATION_UNKNOWN);
 		if (!cpu_stopped(logical_cpu))
 			continue;
 		set_cpu_present(logical_cpu, true);
@@ -403,7 +401,7 @@ static int smp_rescan_cpus_sclp(cpumask_t avail)
 		if (cpu_known(cpu_id))
 			continue;
 		__cpu_logical_map[logical_cpu] = cpu_id;
-		smp_cpu_polarization[logical_cpu] = POLARIZATION_UNKNWN;
+		cpu_set_polarization(logical_cpu, POLARIZATION_UNKNOWN);
 		set_cpu_present(logical_cpu, true);
 		if (cpu >= info->configured)
 			smp_cpu_state[logical_cpu] = CPU_STATE_STANDBY;
@@ -806,7 +804,7 @@ void __init smp_prepare_boot_cpu(void)
 	S390_lowcore.percpu_offset = __per_cpu_offset[0];
 	current_set[0] = current;
 	smp_cpu_state[0] = CPU_STATE_CONFIGURED;
-	smp_cpu_polarization[0] = POLARIZATION_UNKNWN;
+	cpu_set_polarization(0, POLARIZATION_UNKNOWN);
 }
 
 void __init smp_cpus_done(unsigned int max_cpus)
@@ -868,7 +866,7 @@ static ssize_t cpu_configure_store(struct sys_device *dev,
 			rc = sclp_cpu_deconfigure(__cpu_logical_map[cpu]);
 			if (!rc) {
 				smp_cpu_state[cpu] = CPU_STATE_STANDBY;
-				smp_cpu_polarization[cpu] = POLARIZATION_UNKNWN;
+				cpu_set_polarization(cpu, POLARIZATION_UNKNOWN);
 			}
 		}
 		break;
@@ -877,7 +875,7 @@ static ssize_t cpu_configure_store(struct sys_device *dev,
 			rc = sclp_cpu_configure(__cpu_logical_map[cpu]);
 			if (!rc) {
 				smp_cpu_state[cpu] = CPU_STATE_CONFIGURED;
-				smp_cpu_polarization[cpu] = POLARIZATION_UNKNWN;
+				cpu_set_polarization(cpu, POLARIZATION_UNKNOWN);
 			}
 		}
 		break;
@@ -892,35 +890,6 @@ out:
 static SYSDEV_ATTR(configure, 0644, cpu_configure_show, cpu_configure_store);
 #endif /* CONFIG_HOTPLUG_CPU */
 
-static ssize_t cpu_polarization_show(struct sys_device *dev,
-				     struct sysdev_attribute *attr, char *buf)
-{
-	int cpu = dev->id;
-	ssize_t count;
-
-	mutex_lock(&smp_cpu_state_mutex);
-	switch (smp_cpu_polarization[cpu]) {
-	case POLARIZATION_HRZ:
-		count = sprintf(buf, "horizontal\n");
-		break;
-	case POLARIZATION_VL:
-		count = sprintf(buf, "vertical:low\n");
-		break;
-	case POLARIZATION_VM:
-		count = sprintf(buf, "vertical:medium\n");
-		break;
-	case POLARIZATION_VH:
-		count = sprintf(buf, "vertical:high\n");
-		break;
-	default:
-		count = sprintf(buf, "unknown\n");
-		break;
-	}
-	mutex_unlock(&smp_cpu_state_mutex);
-	return count;
-}
-static SYSDEV_ATTR(polarization, 0444, cpu_polarization_show, NULL);
-
 static ssize_t show_cpu_address(struct sys_device *dev,
 				struct sysdev_attribute *attr, char *buf)
 {
@@ -928,13 +897,11 @@ static ssize_t show_cpu_address(struct sys_device *dev,
 }
 static SYSDEV_ATTR(address, 0444, show_cpu_address, NULL);
 
-
 static struct attribute *cpu_common_attrs[] = {
 #ifdef CONFIG_HOTPLUG_CPU
 	&attr_configure.attr,
 #endif
 	&attr_address.attr,
-	&attr_polarization.attr,
 	NULL,
 };
 
@@ -1055,11 +1022,20 @@ static int __devinit smp_add_present_cpu(int cpu)
 	rc = sysfs_create_group(&s->kobj, &cpu_common_attr_group);
 	if (rc)
 		goto out_cpu;
-	if (!cpu_online(cpu))
-		goto out;
-	rc = sysfs_create_group(&s->kobj, &cpu_online_attr_group);
-	if (!rc)
-		return 0;
+	if (cpu_online(cpu)) {
+		rc = sysfs_create_group(&s->kobj, &cpu_online_attr_group);
+		if (rc)
+			goto out_online;
+	}
+	rc = topology_cpu_init(c);
+	if (rc)
+		goto out_topology;
+	return 0;
+
+out_topology:
+	if (cpu_online(cpu))
+		sysfs_remove_group(&s->kobj, &cpu_online_attr_group);
+out_online:
 	sysfs_remove_group(&s->kobj, &cpu_common_attr_group);
 out_cpu:
 #ifdef CONFIG_HOTPLUG_CPU
@@ -1111,61 +1087,16 @@ static ssize_t __ref rescan_store(struct sysdev_class *class,
 static SYSDEV_CLASS_ATTR(rescan, 0200, NULL, rescan_store);
 #endif /* CONFIG_HOTPLUG_CPU */
 
-static ssize_t dispatching_show(struct sysdev_class *class,
-				struct sysdev_class_attribute *attr,
-				char *buf)
+static int __init s390_smp_init(void)
 {
-	ssize_t count;
-
-	mutex_lock(&smp_cpu_state_mutex);
-	count = sprintf(buf, "%d\n", cpu_management);
-	mutex_unlock(&smp_cpu_state_mutex);
-	return count;
-}
-
-static ssize_t dispatching_store(struct sysdev_class *dev,
-				 struct sysdev_class_attribute *attr,
-				 const char *buf,
-				 size_t count)
-{
-	int val, rc;
-	char delim;
-
-	if (sscanf(buf, "%d %c", &val, &delim) != 1)
-		return -EINVAL;
-	if (val != 0 && val != 1)
-		return -EINVAL;
-	rc = 0;
-	get_online_cpus();
-	mutex_lock(&smp_cpu_state_mutex);
-	if (cpu_management == val)
-		goto out;
-	rc = topology_set_cpu_management(val);
-	if (!rc)
-		cpu_management = val;
-out:
-	mutex_unlock(&smp_cpu_state_mutex);
-	put_online_cpus();
-	return rc ? rc : count;
-}
-static SYSDEV_CLASS_ATTR(dispatching, 0644, dispatching_show,
-			 dispatching_store);
-
-static int __init topology_init(void)
-{
-	int cpu;
-	int rc;
+	int cpu, rc;
 
 	register_cpu_notifier(&smp_cpu_nb);
-
 #ifdef CONFIG_HOTPLUG_CPU
 	rc = sysdev_class_create_file(&cpu_sysdev_class, &attr_rescan);
 	if (rc)
 		return rc;
 #endif
-	rc = sysdev_class_create_file(&cpu_sysdev_class, &attr_dispatching);
-	if (rc)
-		return rc;
 	for_each_present_cpu(cpu) {
 		rc = smp_add_present_cpu(cpu);
 		if (rc)
@@ -1173,4 +1104,4 @@ static int __init topology_init(void)
 	}
 	return 0;
 }
-subsys_initcall(topology_init);
+subsys_initcall(s390_smp_init);
diff --git a/arch/s390/kernel/topology.c b/arch/s390/kernel/topology.c
index fdb5b8cb260f..621f89e36c8a 100644
--- a/arch/s390/kernel/topology.c
+++ b/arch/s390/kernel/topology.c
@@ -6,17 +6,17 @@
 #define KMSG_COMPONENT "cpu"
 #define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
 
-#include <linux/kernel.h>
-#include <linux/mm.h>
-#include <linux/init.h>
-#include <linux/device.h>
+#include <linux/workqueue.h>
 #include <linux/bootmem.h>
+#include <linux/cpuset.h>
+#include <linux/device.h>
+#include <linux/kernel.h>
 #include <linux/sched.h>
-#include <linux/workqueue.h>
+#include <linux/init.h>
+#include <linux/delay.h>
 #include <linux/cpu.h>
 #include <linux/smp.h>
-#include <linux/cpuset.h>
-#include <asm/delay.h>
+#include <linux/mm.h>
 
 #define PTF_HORIZONTAL	(0UL)
 #define PTF_VERTICAL	(1UL)
@@ -41,11 +41,12 @@ static struct mask_info core_info;
 cpumask_t cpu_core_map[NR_CPUS];
 unsigned char cpu_core_id[NR_CPUS];
 
-#ifdef CONFIG_SCHED_BOOK
 static struct mask_info book_info;
 cpumask_t cpu_book_map[NR_CPUS];
 unsigned char cpu_book_id[NR_CPUS];
-#endif
+
+/* smp_cpu_state_mutex must be held when accessing this array */
+int cpu_polarization[NR_CPUS];
 
 static cpumask_t cpu_group_map(struct mask_info *info, unsigned int cpu)
 {
@@ -85,10 +86,8 @@ static struct mask_info *add_cpus_to_mask(struct topology_cpu *tl_cpu,
 		for_each_present_cpu(lcpu) {
 			if (cpu_logical_map(lcpu) != rcpu)
 				continue;
-#ifdef CONFIG_SCHED_BOOK
 			cpumask_set_cpu(lcpu, &book->mask);
 			cpu_book_id[lcpu] = book->id;
-#endif
 			cpumask_set_cpu(lcpu, &core->mask);
 			if (z10) {
 				cpu_core_id[lcpu] = rcpu;
@@ -96,7 +95,7 @@ static struct mask_info *add_cpus_to_mask(struct topology_cpu *tl_cpu,
 			} else {
 				cpu_core_id[lcpu] = core->id;
 			}
-			smp_cpu_polarization[lcpu] = tl_cpu->pp;
+			cpu_set_polarization(lcpu, tl_cpu->pp);
 		}
 	}
 	return core;
@@ -111,13 +110,11 @@ static void clear_masks(void)
 		cpumask_clear(&info->mask);
 		info = info->next;
 	}
-#ifdef CONFIG_SCHED_BOOK
 	info = &book_info;
 	while (info) {
 		cpumask_clear(&info->mask);
 		info = info->next;
 	}
-#endif
 }
 
 static union topology_entry *next_tle(union topology_entry *tle)
@@ -129,26 +126,19 @@ static union topology_entry *next_tle(union topology_entry *tle)
 
 static void tl_to_cores(struct sysinfo_15_1_x *info)
 {
-#ifdef CONFIG_SCHED_BOOK
-	struct mask_info *book = &book_info;
-	struct cpuid cpu_id;
-#else
-	struct mask_info *book = NULL;
-#endif
 	struct mask_info *core = &core_info;
+	struct mask_info *book = &book_info;
 	union topology_entry *tle, *end;
+	struct cpuid cpu_id;
 	int z10 = 0;
 
-#ifdef CONFIG_SCHED_BOOK
 	get_cpu_id(&cpu_id);
 	z10 = cpu_id.machine == 0x2097 || cpu_id.machine == 0x2098;
-#endif
 	spin_lock_irq(&topology_lock);
 	clear_masks();
 	tle = info->tle;
 	end = (union topology_entry *)((unsigned long)info + info->length);
 	while (tle < end) {
-#ifdef CONFIG_SCHED_BOOK
 		if (z10) {
 			switch (tle->nl) {
 			case 1:
@@ -165,14 +155,11 @@ static void tl_to_cores(struct sysinfo_15_1_x *info)
 			tle = next_tle(tle);
 			continue;
 		}
-#endif
 		switch (tle->nl) {
-#ifdef CONFIG_SCHED_BOOK
 		case 2:
 			book = book->next;
 			book->id = tle->container.id;
 			break;
-#endif
 		case 1:
 			core = core->next;
 			core->id = tle->container.id;
@@ -196,7 +183,7 @@ static void topology_update_polarization_simple(void)
 
 	mutex_lock(&smp_cpu_state_mutex);
 	for_each_possible_cpu(cpu)
-		smp_cpu_polarization[cpu] = POLARIZATION_HRZ;
+		cpu_set_polarization(cpu, POLARIZATION_HRZ);
 	mutex_unlock(&smp_cpu_state_mutex);
 }
 
@@ -215,8 +202,7 @@ static int ptf(unsigned long fc)
 
 int topology_set_cpu_management(int fc)
 {
-	int cpu;
-	int rc;
+	int cpu, rc;
 
 	if (!MACHINE_HAS_TOPOLOGY)
 		return -EOPNOTSUPP;
@@ -227,7 +213,7 @@ int topology_set_cpu_management(int fc)
 	if (rc)
 		return -EBUSY;
 	for_each_possible_cpu(cpu)
-		smp_cpu_polarization[cpu] = POLARIZATION_UNKNWN;
+		cpu_set_polarization(cpu, POLARIZATION_UNKNOWN);
 	return rc;
 }
 
@@ -239,22 +225,18 @@ static void update_cpu_core_map(void)
 	spin_lock_irqsave(&topology_lock, flags);
 	for_each_possible_cpu(cpu) {
 		cpu_core_map[cpu] = cpu_group_map(&core_info, cpu);
-#ifdef CONFIG_SCHED_BOOK
 		cpu_book_map[cpu] = cpu_group_map(&book_info, cpu);
-#endif
 	}
 	spin_unlock_irqrestore(&topology_lock, flags);
 }
 
 void store_topology(struct sysinfo_15_1_x *info)
 {
-#ifdef CONFIG_SCHED_BOOK
 	int rc;
 
 	rc = stsi(info, 15, 1, 3);
 	if (rc != -ENOSYS)
 		return;
-#endif
 	stsi(info, 15, 1, 2);
 }
 
@@ -313,23 +295,6 @@ static int __init early_parse_topology(char *p)
 }
 early_param("topology", early_parse_topology);
 
-static int __init init_topology_update(void)
-{
-	int rc;
-
-	rc = 0;
-	if (!MACHINE_HAS_TOPOLOGY) {
-		topology_update_polarization_simple();
-		goto out;
-	}
-	init_timer_deferrable(&topology_timer);
-	set_topology_timer();
-out:
-	update_cpu_core_map();
-	return rc;
-}
-__initcall(init_topology_update);
-
 static void __init alloc_masks(struct sysinfo_15_1_x *info,
 			       struct mask_info *mask, int offset)
 {
@@ -357,10 +322,107 @@ void __init s390_init_cpu_topology(void)
 	store_topology(info);
 	pr_info("The CPU configuration topology of the machine is:");
 	for (i = 0; i < TOPOLOGY_NR_MAG; i++)
-		printk(" %d", info->mag[i]);
-	printk(" / %d\n", info->mnest);
+		printk(KERN_CONT " %d", info->mag[i]);
+	printk(KERN_CONT " / %d\n", info->mnest);
 	alloc_masks(info, &core_info, 1);
-#ifdef CONFIG_SCHED_BOOK
 	alloc_masks(info, &book_info, 2);
-#endif
 }
+
+static int cpu_management;
+
+static ssize_t dispatching_show(struct sysdev_class *class,
+				struct sysdev_class_attribute *attr,
+				char *buf)
+{
+	ssize_t count;
+
+	mutex_lock(&smp_cpu_state_mutex);
+	count = sprintf(buf, "%d\n", cpu_management);
+	mutex_unlock(&smp_cpu_state_mutex);
+	return count;
+}
+
+static ssize_t dispatching_store(struct sysdev_class *dev,
+				 struct sysdev_class_attribute *attr,
+				 const char *buf,
+				 size_t count)
+{
+	int val, rc;
+	char delim;
+
+	if (sscanf(buf, "%d %c", &val, &delim) != 1)
+		return -EINVAL;
+	if (val != 0 && val != 1)
+		return -EINVAL;
+	rc = 0;
+	get_online_cpus();
+	mutex_lock(&smp_cpu_state_mutex);
+	if (cpu_management == val)
+		goto out;
+	rc = topology_set_cpu_management(val);
+	if (!rc)
+		cpu_management = val;
+out:
+	mutex_unlock(&smp_cpu_state_mutex);
+	put_online_cpus();
+	return rc ? rc : count;
+}
+static SYSDEV_CLASS_ATTR(dispatching, 0644, dispatching_show,
+			 dispatching_store);
+
+static ssize_t cpu_polarization_show(struct sys_device *dev,
+				     struct sysdev_attribute *attr, char *buf)
+{
+	int cpu = dev->id;
+	ssize_t count;
+
+	mutex_lock(&smp_cpu_state_mutex);
+	switch (cpu_read_polarization(cpu)) {
+	case POLARIZATION_HRZ:
+		count = sprintf(buf, "horizontal\n");
+		break;
+	case POLARIZATION_VL:
+		count = sprintf(buf, "vertical:low\n");
+		break;
+	case POLARIZATION_VM:
+		count = sprintf(buf, "vertical:medium\n");
+		break;
+	case POLARIZATION_VH:
+		count = sprintf(buf, "vertical:high\n");
+		break;
+	default:
+		count = sprintf(buf, "unknown\n");
+		break;
+	}
+	mutex_unlock(&smp_cpu_state_mutex);
+	return count;
+}
+static SYSDEV_ATTR(polarization, 0444, cpu_polarization_show, NULL);
+
+static struct attribute *topology_cpu_attrs[] = {
+	&attr_polarization.attr,
+	NULL,
+};
+
+static struct attribute_group topology_cpu_attr_group = {
+	.attrs = topology_cpu_attrs,
+};
+
+int topology_cpu_init(struct cpu *cpu)
+{
+	return sysfs_create_group(&cpu->sysdev.kobj, &topology_cpu_attr_group);
+}
+
+static int __init topology_init(void)
+{
+	if (!MACHINE_HAS_TOPOLOGY) {
+		topology_update_polarization_simple();
+		goto out;
+	}
+	init_timer_deferrable(&topology_timer);
+	set_topology_timer();
+out:
+	update_cpu_core_map();
+	return sysdev_class_create_file(&cpu_sysdev_class, &attr_dispatching);
+}
+device_initcall(topology_init);