[S390] cpu topology support for s390.

Add s390 backend so we can give the scheduler some hints about the
cpu topology.

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

arch/s390/kernel/topology.c

@@ -0,0 +1,272 @@
+/*
+ *  arch/s390/kernel/topology.c
+ *
+ *    Copyright IBM Corp. 2007
+ *    Author(s): Heiko Carstens <heiko.carstens@de.ibm.com>
+ */
+
+#include <linux/kernel.h>
+#include <linux/mm.h>
+#include <linux/init.h>
+#include <linux/device.h>
+#include <linux/bootmem.h>
+#include <linux/sched.h>
+#include <linux/workqueue.h>
+#include <linux/cpu.h>
+#include <linux/smp.h>
+#include <asm/delay.h>
+#include <asm/s390_ext.h>
+#include <asm/sysinfo.h>
+
+#define CPU_BITS 64
+
+struct tl_cpu {
+	unsigned char reserved[6];
+	unsigned short origin;
+	unsigned long mask[CPU_BITS / BITS_PER_LONG];
+};
+
+struct tl_container {
+	unsigned char reserved[8];
+};
+
+union tl_entry {
+	unsigned char nl;
+	struct tl_cpu cpu;
+	struct tl_container container;
+};
+
+#define NR_MAG 6
+
+struct tl_info {
+	unsigned char reserved0[2];
+	unsigned short length;
+	unsigned char mag[NR_MAG];
+	unsigned char reserved1;
+	unsigned char mnest;
+	unsigned char reserved2[4];
+	union tl_entry tle[0];
+};
+
+struct core_info {
+	struct core_info *next;
+	cpumask_t mask;
+};
+
+static void topology_work_fn(struct work_struct *work);
+static struct tl_info *tl_info;
+static struct core_info core_info;
+static int machine_has_topology;
+static int machine_has_topology_irq;
+static struct timer_list topology_timer;
+static void set_topology_timer(void);
+static DECLARE_WORK(topology_work, topology_work_fn);
+
+cpumask_t cpu_coregroup_map(unsigned int cpu)
+{
+	struct core_info *core = &core_info;
+	cpumask_t mask;
+
+	cpus_clear(mask);
+	if (!machine_has_topology)
+		return cpu_present_map;
+	mutex_lock(&smp_cpu_state_mutex);
+	while (core) {
+		if (cpu_isset(cpu, core->mask)) {
+			mask = core->mask;
+			break;
+		}
+		core = core->next;
+	}
+	mutex_unlock(&smp_cpu_state_mutex);
+	if (cpus_empty(mask))
+		mask = cpumask_of_cpu(cpu);
+	return mask;
+}
+
+static void add_cpus_to_core(struct tl_cpu *tl_cpu, struct core_info *core)
+{
+	unsigned int cpu;
+
+	for (cpu = find_first_bit(&tl_cpu->mask[0], CPU_BITS);
+	     cpu < CPU_BITS;
+	     cpu = find_next_bit(&tl_cpu->mask[0], CPU_BITS, cpu + 1))
+	{
+		unsigned int rcpu, lcpu;
+
+		rcpu = CPU_BITS - 1 - cpu + tl_cpu->origin;
+		for_each_present_cpu(lcpu) {
+			if (__cpu_logical_map[lcpu] == rcpu)
+				cpu_set(lcpu, core->mask);
+		}
+	}
+}
+
+static void clear_cores(void)
+{
+	struct core_info *core = &core_info;
+
+	while (core) {
+		cpus_clear(core->mask);
+		core = core->next;
+	}
+}
+
+static union tl_entry *next_tle(union tl_entry *tle)
+{
+	if (tle->nl)
+		return (union tl_entry *)((struct tl_container *)tle + 1);
+	else
+		return (union tl_entry *)((struct tl_cpu *)tle + 1);
+}
+
+static void tl_to_cores(struct tl_info *info)
+{
+	union tl_entry *tle, *end;
+	struct core_info *core = &core_info;
+
+	mutex_lock(&smp_cpu_state_mutex);
+	clear_cores();
+	tle = (union tl_entry *)&info->tle;
+	end = (union tl_entry *)((unsigned long)info + info->length);
+	while (tle < end) {
+		switch (tle->nl) {
+		case 5:
+		case 4:
+		case 3:
+		case 2:
+			break;
+		case 1:
+			core = core->next;
+			break;
+		case 0:
+			add_cpus_to_core(&tle->cpu, core);
+			break;
+		default:
+			clear_cores();
+			machine_has_topology = 0;
+			return;
+		}
+		tle = next_tle(tle);
+	}
+	mutex_unlock(&smp_cpu_state_mutex);
+}
+
+static int ptf(void)
+{
+	int rc;
+
+	asm volatile(
+		"	.insn	rre,0xb9a20000,%1,%1\n"
+		"	ipm	%0\n"
+		"	srl	%0,28\n"
+		: "=d" (rc)
+		: "d" (2UL)  : "cc");
+	return rc;
+}
+
+void arch_update_cpu_topology(void)
+{
+	struct tl_info *info = tl_info;
+	struct sys_device *sysdev;
+	int cpu;
+
+	if (!machine_has_topology)
+		return;
+	ptf();
+	stsi(info, 15, 1, 2);
+	tl_to_cores(info);
+	for_each_online_cpu(cpu) {
+		sysdev = get_cpu_sysdev(cpu);
+		kobject_uevent(&sysdev->kobj, KOBJ_CHANGE);
+	}
+}
+
+static void topology_work_fn(struct work_struct *work)
+{
+	arch_reinit_sched_domains();
+}
+
+static void topology_timer_fn(unsigned long ignored)
+{
+	if (ptf())
+		schedule_work(&topology_work);
+	set_topology_timer();
+}
+
+static void set_topology_timer(void)
+{
+	topology_timer.function = topology_timer_fn;
+	topology_timer.data = 0;
+	topology_timer.expires = jiffies + 60 * HZ;
+	add_timer(&topology_timer);
+}
+
+static void topology_interrupt(__u16 code)
+{
+	schedule_work(&topology_work);
+}
+
+static int __init init_topology_update(void)
+{
+	int rc;
+
+	if (!machine_has_topology)
+		return 0;
+	init_timer(&topology_timer);
+	if (machine_has_topology_irq) {
+		rc = register_external_interrupt(0x2005, topology_interrupt);
+		if (rc)
+			return rc;
+		ctl_set_bit(0, 8);
+	}
+	else
+		set_topology_timer();
+	return 0;
+}
+__initcall(init_topology_update);
+
+void __init s390_init_cpu_topology(void)
+{
+	unsigned long long facility_bits;
+	struct tl_info *info;
+	struct core_info *core;
+	int nr_cores;
+	int i;
+
+	if (stfle(&facility_bits, 1) <= 0)
+		return;
+	if (!(facility_bits & (1ULL << 52)) || !(facility_bits & (1ULL << 61)))
+		return;
+	machine_has_topology = 1;
+
+	if (facility_bits & (1ULL << 51))
+		machine_has_topology_irq = 1;
+
+	tl_info = alloc_bootmem_pages(PAGE_SIZE);
+	if (!tl_info)
+		goto error;
+	info = tl_info;
+	stsi(info, 15, 1, 2);
+
+	nr_cores = info->mag[NR_MAG - 2];
+	for (i = 0; i < info->mnest - 2; i++)
+		nr_cores *= info->mag[NR_MAG - 3 - i];
+
+	printk(KERN_INFO "CPU topology:");
+	for (i = 0; i < NR_MAG; i++)
+		printk(" %d", info->mag[i]);
+	printk(" / %d\n", info->mnest);
+
+	core = &core_info;
+	for (i = 0; i < nr_cores; i++) {
+		core->next = alloc_bootmem(sizeof(struct core_info));
+		core = core->next;
+		if (!core)
+			goto error;
+	}
+	return;
+error:
+	machine_has_topology = 0;
+	machine_has_topology_irq = 0;
+}