/*
 *  arch/s390/kernel/smp.c
 *
 *    Copyright IBM Corp. 1999, 2009
 *    Author(s): Denis Joseph Barrow (djbarrow@de.ibm.com,barrow_dj@yahoo.com),
 *               Martin Schwidefsky (schwidefsky@de.ibm.com)
 *               Heiko Carstens (heiko.carstens@de.ibm.com)
 *
 *  based on other smp stuff by
 *    (c) 1995 Alan Cox, CymruNET Ltd  <alan@cymru.net>
 *    (c) 1998 Ingo Molnar
 *
 * We work with logical cpu numbering everywhere we can. The only
 * functions using the real cpu address (got from STAP) are the sigp
 * functions. For all other functions we use the identity mapping.
 * That means that cpu_number_map[i] == i for every cpu. cpu_number_map is
 * used e.g. to find the idle task belonging to a logical cpu. Every array
 * in the kernel is sorted by the logical cpu number and not by the physical
 * one which is causing all the confusion with __cpu_logical_map and
 * cpu_number_map in other architectures.
 */

#define KMSG_COMPONENT "cpu"
#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt

#include <linux/module.h>
#include <linux/init.h>
#include <linux/mm.h>
#include <linux/err.h>
#include <linux/spinlock.h>
#include <linux/kernel_stat.h>
#include <linux/delay.h>
#include <linux/cache.h>
#include <linux/interrupt.h>
#include <linux/irqflags.h>
#include <linux/cpu.h>
#include <linux/timex.h>
#include <linux/bootmem.h>
#include <asm/ipl.h>
#include <asm/setup.h>
#include <asm/sigp.h>
#include <asm/pgalloc.h>
#include <asm/irq.h>
#include <asm/s390_ext.h>
#include <asm/cpcmd.h>
#include <asm/tlbflush.h>
#include <asm/timer.h>
#include <asm/lowcore.h>
#include <asm/sclp.h>
#include <asm/cputime.h>
#include <asm/vdso.h>
#include <asm/cpu.h>
#include "entry.h"

static struct task_struct *current_set[NR_CPUS];

static u8 smp_cpu_type;
static int smp_use_sigp_detection;

enum s390_cpu_state {
        CPU_STATE_STANDBY,
        CPU_STATE_CONFIGURED,
};

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);

static void smp_ext_bitcall(int, ec_bit_sig);

static int cpu_stopped(int cpu)
{
        __u32 status;

        switch (signal_processor_ps(&status, 0, cpu, sigp_sense)) {
        case sigp_status_stored:
                /* Check for stopped and check stop state */
                if (status & 0x50)
                        return 1;
                break;
        default:
                break;
        }
        return 0;
}

void smp_send_stop(void)
{
        int cpu, rc;

        /* Disable all interrupts/machine checks */
        __load_psw_mask(psw_kernel_bits & ~PSW_MASK_MCHECK);
        trace_hardirqs_off();

        /* stop all processors */
        for_each_online_cpu(cpu) {
                if (cpu == smp_processor_id())
                        continue;
                do {
                        rc = signal_processor(cpu, sigp_stop);
                } while (rc == sigp_busy);

                while (!cpu_stopped(cpu))
                        cpu_relax();
        }
}

/*
 * This is the main routine where commands issued by other
 * cpus are handled.
 */

static void do_ext_call_interrupt(__u16 code)
{
        unsigned long bits;

        /*
         * handle bit signal external calls
         *
         * For the ec_schedule signal we have to do nothing. All the work
         * is done automatically when we return from the interrupt.
         */
        bits = xchg(&S390_lowcore.ext_call_fast, 0);

        if (test_bit(ec_call_function, &bits))
                generic_smp_call_function_interrupt();

        if (test_bit(ec_call_function_single, &bits))
                generic_smp_call_function_single_interrupt();
}

/*
 * Send an external call sigp to another cpu and return without waiting
 * for its completion.
 */
static void smp_ext_bitcall(int cpu, ec_bit_sig sig)
{
        /*
         * Set signaling bit in lowcore of target cpu and kick it
         */
        set_bit(sig, (unsigned long *) &lowcore_ptr[cpu]->ext_call_fast);
        while (signal_processor(cpu, sigp_emergency_signal) == sigp_busy)
                udelay(10);
}

void arch_send_call_function_ipi_mask(const struct cpumask *mask)
{
        int cpu;

        for_each_cpu(cpu, mask)
                smp_ext_bitcall(cpu, ec_call_function);
}

void arch_send_call_function_single_ipi(int cpu)
{
        smp_ext_bitcall(cpu, ec_call_function_single);
}

#ifndef CONFIG_64BIT
/*
 * this function sends a 'purge tlb' signal to another CPU.
 */
static void smp_ptlb_callback(void *info)
{
        __tlb_flush_local();
}

void smp_ptlb_all(void)
{
        on_each_cpu(smp_ptlb_callback, NULL, 1);
}
EXPORT_SYMBOL(smp_ptlb_all);
#endif /* ! CONFIG_64BIT */

/*
 * this function sends a 'reschedule' IPI to another CPU.
 * it goes straight through and wastes no time serializing
 * anything. Worst case is that we lose a reschedule ...
 */
void smp_send_reschedule(int cpu)
{
        smp_ext_bitcall(cpu, ec_schedule);
}

/*
 * parameter area for the set/clear control bit callbacks
 */
struct ec_creg_mask_parms {
        unsigned long orvals[16];
        unsigned long andvals[16];
};

/*
 * callback for setting/clearing control bits
 */
static void smp_ctl_bit_callback(void *info)
{
        struct ec_creg_mask_parms *pp = info;
        unsigned long cregs[16];
        int i;

        __ctl_store(cregs, 0, 15);
        for (i = 0; i <= 15; i++)
                cregs[i] = (cregs[i] & pp->andvals[i]) | pp->orvals[i];
        __ctl_load(cregs, 0, 15);
}

/*
 * Set a bit in a control register of all cpus
 */
void smp_ctl_set_bit(int cr, int bit)
{
        struct ec_creg_mask_parms parms;

        memset(&parms.orvals, 0, sizeof(parms.orvals));
        memset(&parms.andvals, 0xff, sizeof(parms.andvals));
        parms.orvals[cr] = 1 << bit;
        on_each_cpu(smp_ctl_bit_callback, &parms, 1);
}
EXPORT_SYMBOL(smp_ctl_set_bit);

/*
 * Clear a bit in a control register of all cpus
 */
void smp_ctl_clear_bit(int cr, int bit)
{
        struct ec_creg_mask_parms parms;

        memset(&parms.orvals, 0, sizeof(parms.orvals));
        memset(&parms.andvals, 0xff, sizeof(parms.andvals));
        parms.andvals[cr] = ~(1L << bit);
        on_each_cpu(smp_ctl_bit_callback, &parms, 1);
}
EXPORT_SYMBOL(smp_ctl_clear_bit);

/*
 * In early ipl state a temp. logically cpu number is needed, so the sigp
 * functions can be used to sense other cpus. Since NR_CPUS is >= 2 on
 * CONFIG_SMP and the ipl cpu is logical cpu 0, it must be 1.
 */
#define CPU_INIT_NO     1

#ifdef CONFIG_ZFCPDUMP

/*
 * zfcpdump_prefix_array holds prefix registers for the following scenario:
 * 64 bit zfcpdump kernel and 31 bit kernel which is to be dumped. We have to
 * save its prefix registers, since they get lost, when switching from 31 bit
 * to 64 bit.
 */
unsigned int zfcpdump_prefix_array[NR_CPUS + 1] \
        __attribute__((__section__(".data")));

static void __init smp_get_save_area(unsigned int cpu, unsigned int phy_cpu)
{
        if (ipl_info.type != IPL_TYPE_FCP_DUMP)
                return;
        if (cpu >= NR_CPUS) {
                pr_warning("CPU %i exceeds the maximum %i and is excluded from "
                           "the dump\n", cpu, NR_CPUS - 1);
                return;
        }
        zfcpdump_save_areas[cpu] = kmalloc(sizeof(union save_area), GFP_KERNEL);
        __cpu_logical_map[CPU_INIT_NO] = (__u16) phy_cpu;
        while (signal_processor(CPU_INIT_NO, sigp_stop_and_store_status) ==
               sigp_busy)
                cpu_relax();
        memcpy(zfcpdump_save_areas[cpu],
               (void *)(unsigned long) store_prefix() + SAVE_AREA_BASE,
               SAVE_AREA_SIZE);
#ifdef CONFIG_64BIT
        /* copy original prefix register */
        zfcpdump_save_areas[cpu]->s390x.pref_reg = zfcpdump_prefix_array[cpu];
#endif
}

union save_area *zfcpdump_save_areas[NR_CPUS + 1];
EXPORT_SYMBOL_GPL(zfcpdump_save_areas);

#else

static inline void smp_get_save_area(unsigned int cpu, unsigned int phy_cpu) { }

#endif /* CONFIG_ZFCPDUMP */

static int cpu_known(int cpu_id)
{
        int cpu;

        for_each_present_cpu(cpu) {
                if (__cpu_logical_map[cpu] == cpu_id)
                        return 1;
        }
        return 0;
}

static int smp_rescan_cpus_sigp(cpumask_t avail)
{
        int cpu_id, logical_cpu;

        logical_cpu = cpumask_first(&avail);
        if (logical_cpu >= nr_cpu_ids)
                return 0;
        for (cpu_id = 0; cpu_id <= MAX_CPU_ADDRESS; cpu_id++) {
                if (cpu_known(cpu_id))
                        continue;
                __cpu_logical_map[logical_cpu] = cpu_id;
                smp_cpu_polarization[logical_cpu] = POLARIZATION_UNKNWN;
                if (!cpu_stopped(logical_cpu))
                        continue;
                cpu_set(logical_cpu, cpu_present_map);
                smp_cpu_state[logical_cpu] = CPU_STATE_CONFIGURED;
                logical_cpu = cpumask_next(logical_cpu, &avail);
                if (logical_cpu >= nr_cpu_ids)
                        break;
        }
        return 0;
}

static int smp_rescan_cpus_sclp(cpumask_t avail)
{
        struct sclp_cpu_info *info;
        int cpu_id, logical_cpu, cpu;
        int rc;

        logical_cpu = cpumask_first(&avail);
        if (logical_cpu >= nr_cpu_ids)
                return 0;
        info = kmalloc(sizeof(*info), GFP_KERNEL);
        if (!info)
                return -ENOMEM;
        rc = sclp_get_cpu_info(info);
        if (rc)
                goto out;
        for (cpu = 0; cpu < info->combined; cpu++) {
                if (info->has_cpu_type && info->cpu[cpu].type != smp_cpu_type)
                        continue;
                cpu_id = info->cpu[cpu].address;
                if (cpu_known(cpu_id))
                        continue;
                __cpu_logical_map[logical_cpu] = cpu_id;
                smp_cpu_polarization[logical_cpu] = POLARIZATION_UNKNWN;
                cpu_set(logical_cpu, cpu_present_map);
                if (cpu >= info->configured)
                        smp_cpu_state[logical_cpu] = CPU_STATE_STANDBY;
                else
                        smp_cpu_state[logical_cpu] = CPU_STATE_CONFIGURED;
                logical_cpu = cpumask_next(logical_cpu, &avail);
                if (logical_cpu >= nr_cpu_ids)
                        break;
        }
out:
        kfree(info);
        return rc;
}

static int __smp_rescan_cpus(void)
{
        cpumask_t avail;

        cpus_xor(avail, cpu_possible_map, cpu_present_map);
        if (smp_use_sigp_detection)
                return smp_rescan_cpus_sigp(avail);
        else
                return smp_rescan_cpus_sclp(avail);
}

static void __init smp_detect_cpus(void)
{
        unsigned int cpu, c_cpus, s_cpus;
        struct sclp_cpu_info *info;
        u16 boot_cpu_addr, cpu_addr;

        c_cpus = 1;
        s_cpus = 0;
        boot_cpu_addr = __cpu_logical_map[0];
        info = kmalloc(sizeof(*info), GFP_KERNEL);
        if (!info)
                panic("smp_detect_cpus failed to allocate memory\n");
        /* Use sigp detection algorithm if sclp doesn't work. */
        if (sclp_get_cpu_info(info)) {
                smp_use_sigp_detection = 1;
                for (cpu = 0; cpu <= MAX_CPU_ADDRESS; cpu++) {
                        if (cpu == boot_cpu_addr)
                                continue;
                        __cpu_logical_map[CPU_INIT_NO] = cpu;
                        if (!cpu_stopped(CPU_INIT_NO))
                                continue;
                        smp_get_save_area(c_cpus, cpu);
                        c_cpus++;
                }
                goto out;
        }

        if (info->has_cpu_type) {
                for (cpu = 0; cpu < info->combined; cpu++) {
                        if (info->cpu[cpu].address == boot_cpu_addr) {
                                smp_cpu_type = info->cpu[cpu].type;
                                break;
                        }
                }
        }

        for (cpu = 0; cpu < info->combined; cpu++) {
                if (info->has_cpu_type && info->cpu[cpu].type != smp_cpu_type)
                        continue;
                cpu_addr = info->cpu[cpu].address;
                if (cpu_addr == boot_cpu_addr)
                        continue;
                __cpu_logical_map[CPU_INIT_NO] = cpu_addr;
                if (!cpu_stopped(CPU_INIT_NO)) {
                        s_cpus++;
                        continue;
                }
                smp_get_save_area(c_cpus, cpu_addr);
                c_cpus++;
        }
out:
        kfree(info);
        pr_info("%d configured CPUs, %d standby CPUs\n", c_cpus, s_cpus);
        get_online_cpus();
        __smp_rescan_cpus();
        put_online_cpus();
}

/*
 *      Activate a secondary processor.
 */
int __cpuinit start_secondary(void *cpuvoid)
{
        /* Setup the cpu */
        cpu_init();
        preempt_disable();
        /* Enable TOD clock interrupts on the secondary cpu. */
        init_cpu_timer();
        /* Enable cpu timer interrupts on the secondary cpu. */
        init_cpu_vtimer();
        /* Enable pfault pseudo page faults on this cpu. */
        pfault_init();

        /* call cpu notifiers */
        notify_cpu_starting(smp_processor_id());
        /* Mark this cpu as online */
        ipi_call_lock();
        cpu_set(smp_processor_id(), cpu_online_map);
        ipi_call_unlock();
        /* Switch on interrupts */
        local_irq_enable();
        /* Print info about this processor */
        print_cpu_info();
        /* cpu_idle will call schedule for us */
        cpu_idle();
        return 0;
}

static void __init smp_create_idle(unsigned int cpu)
{
        struct task_struct *p;

        /*
         *  don't care about the psw and regs settings since we'll never
         *  reschedule the forked task.
         */
        p = fork_idle(cpu);
        if (IS_ERR(p))
                panic("failed fork for CPU %u: %li", cpu, PTR_ERR(p));
        current_set[cpu] = p;
}

static int __cpuinit smp_alloc_lowcore(int cpu)
{
        unsigned long async_stack, panic_stack;
        struct _lowcore *lowcore;

        lowcore = (void *) __get_free_pages(GFP_KERNEL | GFP_DMA, LC_ORDER);
        if (!lowcore)
                return -ENOMEM;
        async_stack = __get_free_pages(GFP_KERNEL, ASYNC_ORDER);
        panic_stack = __get_free_page(GFP_KERNEL);
        if (!panic_stack || !async_stack)
                goto out;
        memcpy(lowcore, &S390_lowcore, 512);
        memset((char *)lowcore + 512, 0, sizeof(*lowcore) - 512);
        lowcore->async_stack = async_stack + ASYNC_SIZE;
        lowcore->panic_stack = panic_stack + PAGE_SIZE;

#ifndef CONFIG_64BIT
        if (MACHINE_HAS_IEEE) {
                unsigned long save_area;

                save_area = get_zeroed_page(GFP_KERNEL);
                if (!save_area)
                        goto out;
                lowcore->extended_save_area_addr = (u32) save_area;
        }
#else
        if (vdso_alloc_per_cpu(cpu, lowcore))
                goto out;
#endif
        lowcore_ptr[cpu] = lowcore;
        return 0;

out:
        free_page(panic_stack);
        free_pages(async_stack, ASYNC_ORDER);
        free_pages((unsigned long) lowcore, LC_ORDER);
        return -ENOMEM;
}

static void smp_free_lowcore(int cpu)
{
        struct _lowcore *lowcore;

        lowcore = lowcore_ptr[cpu];
#ifndef CONFIG_64BIT
        if (MACHINE_HAS_IEEE)
                free_page((unsigned long) lowcore->extended_save_area_addr);
#else
        vdso_free_per_cpu(cpu, lowcore);
#endif
        free_page(lowcore->panic_stack - PAGE_SIZE);
        free_pages(lowcore->async_stack - ASYNC_SIZE, ASYNC_ORDER);
        free_pages((unsigned long) lowcore, LC_ORDER);
        lowcore_ptr[cpu] = NULL;
}

/* Upping and downing of CPUs */
int __cpuinit __cpu_up(unsigned int cpu)
{
        struct task_struct *idle;
        struct _lowcore *cpu_lowcore;
        struct stack_frame *sf;
        sigp_ccode ccode;
        u32 lowcore;

        if (smp_cpu_state[cpu] != CPU_STATE_CONFIGURED)
                return -EIO;
        if (smp_alloc_lowcore(cpu))
                return -ENOMEM;
        do {
                ccode = signal_processor(cpu, sigp_initial_cpu_reset);
                if (ccode == sigp_busy)
                        udelay(10);
                if (ccode == sigp_not_operational)
                        goto err_out;
        } while (ccode == sigp_busy);

        lowcore = (u32)(unsigned long)lowcore_ptr[cpu];
        while (signal_processor_p(lowcore, cpu, sigp_set_prefix) == sigp_busy)
                udelay(10);

        idle = current_set[cpu];
        cpu_lowcore = lowcore_ptr[cpu];
        cpu_lowcore->kernel_stack = (unsigned long)
                task_stack_page(idle) + THREAD_SIZE;
        cpu_lowcore->thread_info = (unsigned long) task_thread_info(idle);
        sf = (struct stack_frame *) (cpu_lowcore->kernel_stack
                                     - sizeof(struct pt_regs)
                                     - sizeof(struct stack_frame));
        memset(sf, 0, sizeof(struct stack_frame));
        sf->gprs[9] = (unsigned long) sf;
        cpu_lowcore->save_area[15] = (unsigned long) sf;
        __ctl_store(cpu_lowcore->cregs_save_area, 0, 15);
        asm volatile(
                "       stam    0,15,0(%0)"
                : : "a" (&cpu_lowcore->access_regs_save_area) : "memory");
        cpu_lowcore->percpu_offset = __per_cpu_offset[cpu];
        cpu_lowcore->current_task = (unsigned long) idle;
        cpu_lowcore->cpu_nr = cpu;
        cpu_lowcore->kernel_asce = S390_lowcore.kernel_asce;
        cpu_lowcore->machine_flags = S390_lowcore.machine_flags;
        cpu_lowcore->ftrace_func = S390_lowcore.ftrace_func;
        eieio();

        while (signal_processor(cpu, sigp_restart) == sigp_busy)
                udelay(10);

        while (!cpu_online(cpu))
                cpu_relax();
        return 0;

err_out:
        smp_free_lowcore(cpu);
        return -EIO;
}

static int __init setup_possible_cpus(char *s)
{
        int pcpus, cpu;

        pcpus = simple_strtoul(s, NULL, 0);
        init_cpu_possible(cpumask_of(0));
        for (cpu = 1; cpu < pcpus && cpu < nr_cpu_ids; cpu++)
                set_cpu_possible(cpu, true);
        return 0;
}
early_param("possible_cpus", setup_possible_cpus);

#ifdef CONFIG_HOTPLUG_CPU

int __cpu_disable(void)
{
        struct ec_creg_mask_parms cr_parms;
        int cpu = smp_processor_id();

        cpu_clear(cpu, cpu_online_map);

        /* Disable pfault pseudo page faults on this cpu. */
        pfault_fini();

        memset(&cr_parms.orvals, 0, sizeof(cr_parms.orvals));
        memset(&cr_parms.andvals, 0xff, sizeof(cr_parms.andvals));

        /* disable all external interrupts */
        cr_parms.orvals[0] = 0;
        cr_parms.andvals[0] = ~(1 << 15 | 1 << 14 | 1 << 13 | 1 << 12 |
                                1 << 11 | 1 << 10 | 1 <<  6 | 1 <<  4);
        /* disable all I/O interrupts */
        cr_parms.orvals[6] = 0;
        cr_parms.andvals[6] = ~(1 << 31 | 1 << 30 | 1 << 29 | 1 << 28 |
                                1 << 27 | 1 << 26 | 1 << 25 | 1 << 24);
        /* disable most machine checks */
        cr_parms.orvals[14] = 0;
        cr_parms.andvals[14] = ~(1 << 28 | 1 << 27 | 1 << 26 |
                                 1 << 25 | 1 << 24);

        smp_ctl_bit_callback(&cr_parms);

        return 0;
}

void __cpu_die(unsigned int cpu)
{
        /* Wait until target cpu is down */
        while (!cpu_stopped(cpu))
                cpu_relax();
        while (signal_processor_p(0, cpu, sigp_set_prefix) == sigp_busy)
                udelay(10);
        smp_free_lowcore(cpu);
        pr_info("Processor %d stopped\n", cpu);
}

void cpu_die(void)
{
        idle_task_exit();
        while (signal_processor(smp_processor_id(), sigp_stop) == sigp_busy)
                cpu_relax();
        for (;;);
}

#endif /* CONFIG_HOTPLUG_CPU */

void __init smp_prepare_cpus(unsigned int max_cpus)
{
#ifndef CONFIG_64BIT
        unsigned long save_area = 0;
#endif
        unsigned long async_stack, panic_stack;
        struct _lowcore *lowcore;
        unsigned int cpu;

        smp_detect_cpus();

        /* request the 0x1201 emergency signal external interrupt */
        if (register_external_interrupt(0x1201, do_ext_call_interrupt) != 0)
                panic("Couldn't request external interrupt 0x1201");
        print_cpu_info();

        /* Reallocate current lowcore, but keep its contents. */
        lowcore = (void *) __get_free_pages(GFP_KERNEL | GFP_DMA, LC_ORDER);
        panic_stack = __get_free_page(GFP_KERNEL);
        async_stack = __get_free_pages(GFP_KERNEL, ASYNC_ORDER);
        BUG_ON(!lowcore || !panic_stack || !async_stack);
#ifndef CONFIG_64BIT
        if (MACHINE_HAS_IEEE)
                save_area = get_zeroed_page(GFP_KERNEL);
#endif
        local_irq_disable();
        local_mcck_disable();
        lowcore_ptr[smp_processor_id()] = lowcore;
        *lowcore = S390_lowcore;
        lowcore->panic_stack = panic_stack + PAGE_SIZE;
        lowcore->async_stack = async_stack + ASYNC_SIZE;
#ifndef CONFIG_64BIT
        if (MACHINE_HAS_IEEE)
                lowcore->extended_save_area_addr = (u32) save_area;
#endif
        set_prefix((u32)(unsigned long) lowcore);
        local_mcck_enable();
        local_irq_enable();
#ifdef CONFIG_64BIT
        if (vdso_alloc_per_cpu(smp_processor_id(), &S390_lowcore))
                BUG();
#endif
        for_each_possible_cpu(cpu)
                if (cpu != smp_processor_id())
                        smp_create_idle(cpu);
}

void __init smp_prepare_boot_cpu(void)
{
        BUG_ON(smp_processor_id() != 0);

        current_thread_info()->cpu = 0;
        cpu_set(0, cpu_present_map);
        cpu_set(0, cpu_online_map);
        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;
}

void __init smp_cpus_done(unsigned int max_cpus)
{
}

/*
 * the frequency of the profiling timer can be changed
 * by writing a multiplier value into /proc/profile.
 *
 * usually you want to run this on all CPUs ;)
 */
int setup_profiling_timer(unsigned int multiplier)
{
        return 0;
}

#ifdef CONFIG_HOTPLUG_CPU
static ssize_t cpu_configure_show(struct sys_device *dev,
                                struct sysdev_attribute *attr, char *buf)
{
        ssize_t count;

        mutex_lock(&smp_cpu_state_mutex);
        count = sprintf(buf, "%d\n", smp_cpu_state[dev->id]);
        mutex_unlock(&smp_cpu_state_mutex);
        return count;
}

static ssize_t cpu_configure_store(struct sys_device *dev,
                                  struct sysdev_attribute *attr,
                                  const char *buf, size_t count)
{
        int cpu = dev->id;
        int val, rc;
        char delim;

        if (sscanf(buf, "%d %c", &val, &delim) != 1)
                return -EINVAL;
        if (val != 0 && val != 1)
                return -EINVAL;

        get_online_cpus();
        mutex_lock(&smp_cpu_state_mutex);
        rc = -EBUSY;
        if (cpu_online(cpu))
                goto out;
        rc = 0;
        switch (val) {
        case 0:
                if (smp_cpu_state[cpu] == CPU_STATE_CONFIGURED) {
                        rc = sclp_cpu_deconfigure(__cpu_logical_map[cpu]);
                        if (!rc) {
                                smp_cpu_state[cpu] = CPU_STATE_STANDBY;
                                smp_cpu_polarization[cpu] = POLARIZATION_UNKNWN;
                        }
                }
                break;
        case 1:
                if (smp_cpu_state[cpu] == CPU_STATE_STANDBY) {
                        rc = sclp_cpu_configure(__cpu_logical_map[cpu]);
                        if (!rc) {
                                smp_cpu_state[cpu] = CPU_STATE_CONFIGURED;
                                smp_cpu_polarization[cpu] = POLARIZATION_UNKNWN;
                        }
                }
                break;
        default:
                break;
        }
out:
        mutex_unlock(&smp_cpu_state_mutex);
        put_online_cpus();
        return rc ? rc : count;
}
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)
{
        return sprintf(buf, "%d\n", __cpu_logical_map[dev->id]);
}
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,
};

static struct attribute_group cpu_common_attr_group = {
        .attrs = cpu_common_attrs,
};

static ssize_t show_capability(struct sys_device *dev,
                                struct sysdev_attribute *attr, char *buf)
{
        unsigned int capability;
        int rc;

        rc = get_cpu_capability(&capability);
        if (rc)
                return rc;
        return sprintf(buf, "%u\n", capability);
}
static SYSDEV_ATTR(capability, 0444, show_capability, NULL);

static ssize_t show_idle_count(struct sys_device *dev,
                                struct sysdev_attribute *attr, char *buf)
{
        struct s390_idle_data *idle;
        unsigned long long idle_count;
        unsigned int sequence;

        idle = &per_cpu(s390_idle, dev->id);
repeat:
        sequence = idle->sequence;
        smp_rmb();
        if (sequence & 1)
                goto repeat;
        idle_count = idle->idle_count;
        if (idle->idle_enter)
                idle_count++;
        smp_rmb();
        if (idle->sequence != sequence)
                goto repeat;
        return sprintf(buf, "%llu\n", idle_count);
}
static SYSDEV_ATTR(idle_count, 0444, show_idle_count, NULL);

static ssize_t show_idle_time(struct sys_device *dev,
                                struct sysdev_attribute *attr, char *buf)
{
        struct s390_idle_data *idle;
        unsigned long long now, idle_time, idle_enter;
        unsigned int sequence;

        idle = &per_cpu(s390_idle, dev->id);
        now = get_clock();
repeat:
        sequence = idle->sequence;
        smp_rmb();
        if (sequence & 1)
                goto repeat;
        idle_time = idle->idle_time;
        idle_enter = idle->idle_enter;
        if (idle_enter != 0ULL && idle_enter < now)
                idle_time += now - idle_enter;
        smp_rmb();
        if (idle->sequence != sequence)
                goto repeat;
        return sprintf(buf, "%llu\n", idle_time >> 12);
}
static SYSDEV_ATTR(idle_time_us, 0444, show_idle_time, NULL);

static struct attribute *cpu_online_attrs[] = {
        &attr_capability.attr,
        &attr_idle_count.attr,
        &attr_idle_time_us.attr,
        NULL,
};

static struct attribute_group cpu_online_attr_group = {
        .attrs = cpu_online_attrs,
};

static int __cpuinit smp_cpu_notify(struct notifier_block *self,
                                    unsigned long action, void *hcpu)
{
        unsigned int cpu = (unsigned int)(long)hcpu;
        struct cpu *c = &per_cpu(cpu_devices, cpu);
        struct sys_device *s = &c->sysdev;
        struct s390_idle_data *idle;

        switch (action) {
        case CPU_ONLINE:
        case CPU_ONLINE_FROZEN:
                idle = &per_cpu(s390_idle, cpu);
                memset(idle, 0, sizeof(struct s390_idle_data));
                if (sysfs_create_group(&s->kobj, &cpu_online_attr_group))
                        return NOTIFY_BAD;
                break;
        case CPU_DEAD:
        case CPU_DEAD_FROZEN:
                sysfs_remove_group(&s->kobj, &cpu_online_attr_group);
                break;
        }
        return NOTIFY_OK;
}

static struct notifier_block __cpuinitdata smp_cpu_nb = {
        .notifier_call = smp_cpu_notify,
};

static int __devinit smp_add_present_cpu(int cpu)
{
        struct cpu *c = &per_cpu(cpu_devices, cpu);
        struct sys_device *s = &c->sysdev;
        int rc;

        c->hotpluggable = 1;
        rc = register_cpu(c, cpu);
        if (rc)
                goto out;
        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;
        sysfs_remove_group(&s->kobj, &cpu_common_attr_group);
out_cpu:
#ifdef CONFIG_HOTPLUG_CPU
        unregister_cpu(c);
#endif
out:
        return rc;
}

#ifdef CONFIG_HOTPLUG_CPU

int __ref smp_rescan_cpus(void)
{
        cpumask_t newcpus;
        int cpu;
        int rc;

        get_online_cpus();
        mutex_lock(&smp_cpu_state_mutex);
        newcpus = cpu_present_map;
        rc = __smp_rescan_cpus();
        if (rc)
                goto out;
        cpus_andnot(newcpus, cpu_present_map, newcpus);
        for_each_cpu_mask(cpu, newcpus) {
                rc = smp_add_present_cpu(cpu);
                if (rc)
                        cpu_clear(cpu, cpu_present_map);
        }
        rc = 0;
out:
        mutex_unlock(&smp_cpu_state_mutex);
        put_online_cpus();
        if (!cpus_empty(newcpus))
                topology_schedule_update();
        return rc;
}

static ssize_t __ref rescan_store(struct sysdev_class *class, const char *buf,
                                  size_t count)
{

        int rc;

        rc = smp_rescan_cpus();
        return rc ? rc : count;
}
static SYSDEV_CLASS_ATTR(rescan, 0200, NULL, rescan_store);
#endif /* CONFIG_HOTPLUG_CPU */

static ssize_t dispatching_show(struct sysdev_class *class, 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, 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;

        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)
                        return rc;
        }
        return 0;
}
subsys_initcall(topology_init);