pmb.c

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/*
 * arch/sh/mm/pmb.c
 *
 * Privileged Space Mapping Buffer (PMB) Support.
 *
 * Copyright (C) 2005 - 2011  Paul Mundt
 * Copyright (C) 2010  Matt Fleming
 *
 * This file is subject to the terms and conditions of the GNU General Public
 * License.  See the file "COPYING" in the main directory of this archive
 * for more details.
 */
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/syscore_ops.h>
#include <linux/cpu.h>
#include <linux/module.h>
#include <linux/bitops.h>
#include <linux/debugfs.h>
#include <linux/fs.h>
#include <linux/seq_file.h>
#include <linux/err.h>
#include <linux/io.h>
#include <linux/spinlock.h>
#include <linux/vmalloc.h>
#include <asm/cacheflush.h>
#include <asm/sizes.h>
#include <asm/uaccess.h>
#include <asm/pgtable.h>
#include <asm/page.h>
#include <asm/mmu.h>
#include <asm/mmu_context.h>

struct pmb_entry;

struct pmb_entry {
    unsigned long vpn;
    unsigned long ppn;
    unsigned long flags;
    unsigned long size;

    raw_spinlock_t lock;

    /*
     * 0 .. NR_PMB_ENTRIES for specific entry selection, or
     * PMB_NO_ENTRY to search for a free one
     */
    int entry;

    /* Adjacent entry link for contiguous multi-entry mappings */
    struct pmb_entry *link;
};

static struct {
    unsigned long size;
    int flag;
} pmb_sizes[] = {
    { .size = SZ_512M, .flag = PMB_SZ_512M, },
    { .size = SZ_128M, .flag = PMB_SZ_128M, },
    { .size = SZ_64M,  .flag = PMB_SZ_64M,  },
    { .size = SZ_16M,  .flag = PMB_SZ_16M,  },
};

static void pmb_unmap_entry(struct pmb_entry *, int depth);

static DEFINE_RWLOCK(pmb_rwlock);
static struct pmb_entry pmb_entry_list[NR_PMB_ENTRIES];
static DECLARE_BITMAP(pmb_map, NR_PMB_ENTRIES);

static unsigned int pmb_iomapping_enabled;

static __always_inline unsigned long mk_pmb_entry(unsigned int entry)
{
    return (entry & PMB_E_MASK) << PMB_E_SHIFT;
}

static __always_inline unsigned long mk_pmb_addr(unsigned int entry)
{
    return mk_pmb_entry(entry) | PMB_ADDR;
}

static __always_inline unsigned long mk_pmb_data(unsigned int entry)
{
    return mk_pmb_entry(entry) | PMB_DATA;
}

static __always_inline unsigned int pmb_ppn_in_range(unsigned long ppn)
{
    return ppn >= __pa(memory_start) && ppn < __pa(memory_end);
}

/*
 * Ensure that the PMB entries match our cache configuration.
 *
 * When we are in 32-bit address extended mode, CCR.CB becomes
 * invalid, so care must be taken to manually adjust cacheable
 * translations.
 */
static __always_inline unsigned long pmb_cache_flags(void)
{
    unsigned long flags = 0;

#if defined(CONFIG_CACHE_OFF)
    flags |= PMB_WT | PMB_UB;
#elif defined(CONFIG_CACHE_WRITETHROUGH)
    flags |= PMB_C | PMB_WT | PMB_UB;
#elif defined(CONFIG_CACHE_WRITEBACK)
    flags |= PMB_C;
#endif

    return flags;
}

/*
 * Convert typical pgprot value to the PMB equivalent
 */
static inline unsigned long pgprot_to_pmb_flags(pgprot_t prot)
{
    unsigned long pmb_flags = 0;
    u64 flags = pgprot_val(prot);

    if (flags & _PAGE_CACHABLE)
        pmb_flags |= PMB_C;
    if (flags & _PAGE_WT)
        pmb_flags |= PMB_WT | PMB_UB;

    return pmb_flags;
}

static inline bool pmb_can_merge(struct pmb_entry *a, struct pmb_entry *b)
{
    return (b->vpn == (a->vpn + a->size)) &&
           (b->ppn == (a->ppn + a->size)) &&
           (b->flags == a->flags);
}

static bool pmb_mapping_exists(unsigned long vaddr, phys_addr_t phys,
                   unsigned long size)
{
    int i;

    read_lock(&pmb_rwlock);

    for (i = 0; i < ARRAY_SIZE(pmb_entry_list); i++) {
        struct pmb_entry *pmbe, *iter;
        unsigned long span;

        if (!test_bit(i, pmb_map))
            continue;

        pmbe = &pmb_entry_list[i];

        /*
         * See if VPN and PPN are bounded by an existing mapping.
         */
        if ((vaddr < pmbe->vpn) || (vaddr >= (pmbe->vpn + pmbe->size)))
            continue;
        if ((phys < pmbe->ppn) || (phys >= (pmbe->ppn + pmbe->size)))
            continue;

        /*
         * Now see if we're in range of a simple mapping.
         */
        if (size <= pmbe->size) {
            read_unlock(&pmb_rwlock);
            return true;
        }

        span = pmbe->size;

        /*
         * Finally for sizes that involve compound mappings, walk
         * the chain.
         */
        for (iter = pmbe->link; iter; iter = iter->link)
            span += iter->size;

        /*
         * Nothing else to do if the range requirements are met.
         */
        if (size <= span) {
            read_unlock(&pmb_rwlock);
            return true;
        }
    }

    read_unlock(&pmb_rwlock);
    return false;
}

static bool pmb_size_valid(unsigned long size)
{
    int i;

    for (i = 0; i < ARRAY_SIZE(pmb_sizes); i++)
        if (pmb_sizes[i].size == size)
            return true;

    return false;
}

static inline bool pmb_addr_valid(unsigned long addr, unsigned long size)
{
    return (addr >= P1SEG && (addr + size - 1) < P3SEG);
}

static inline bool pmb_prot_valid(pgprot_t prot)
{
    return (pgprot_val(prot) & _PAGE_USER) == 0;
}

static int pmb_size_to_flags(unsigned long size)
{
    int i;

    for (i = 0; i < ARRAY_SIZE(pmb_sizes); i++)
        if (pmb_sizes[i].size == size)
            return pmb_sizes[i].flag;

    return 0;
}

static int pmb_alloc_entry(void)
{
    int pos;

    pos = find_first_zero_bit(pmb_map, NR_PMB_ENTRIES);
    if (pos >= 0 && pos < NR_PMB_ENTRIES)
        __set_bit(pos, pmb_map);
    else
        pos = -ENOSPC;

    return pos;
}

static struct pmb_entry *pmb_alloc(unsigned long vpn, unsigned long ppn,
                   unsigned long flags, int entry)
{
    struct pmb_entry *pmbe;
    unsigned long irqflags;
    void *ret = NULL;
    int pos;

    write_lock_irqsave(&pmb_rwlock, irqflags);

    if (entry == PMB_NO_ENTRY) {
        pos = pmb_alloc_entry();
        if (unlikely(pos < 0)) {
            ret = ERR_PTR(pos);
            goto out;
        }
    } else {
        if (__test_and_set_bit(entry, pmb_map)) {
            ret = ERR_PTR(-ENOSPC);
            goto out;
        }

        pos = entry;
    }

    write_unlock_irqrestore(&pmb_rwlock, irqflags);

    pmbe = &pmb_entry_list[pos];

    memset(pmbe, 0, sizeof(struct pmb_entry));

    raw_spin_lock_init(&pmbe->lock);

    pmbe->vpn   = vpn;
    pmbe->ppn   = ppn;
    pmbe->flags = flags;
    pmbe->entry = pos;

    return pmbe;

out:
    write_unlock_irqrestore(&pmb_rwlock, irqflags);
    return ret;
}

static void pmb_free(struct pmb_entry *pmbe)
{
    __clear_bit(pmbe->entry, pmb_map);

    pmbe->entry = PMB_NO_ENTRY;
    pmbe->link  = NULL;
}

/*
 * Must be run uncached.
 */
static void __set_pmb_entry(struct pmb_entry *pmbe)
{
    unsigned long addr, data;

    addr = mk_pmb_addr(pmbe->entry);
    data = mk_pmb_data(pmbe->entry);

    jump_to_uncached();

    /* Set V-bit */
    __raw_writel(pmbe->vpn | PMB_V, addr);
    __raw_writel(pmbe->ppn | pmbe->flags | PMB_V, data);

    back_to_cached();
}

static void __clear_pmb_entry(struct pmb_entry *pmbe)
{
    unsigned long addr, data;
    unsigned long addr_val, data_val;

    addr = mk_pmb_addr(pmbe->entry);
    data = mk_pmb_data(pmbe->entry);

    addr_val = __raw_readl(addr);
    data_val = __raw_readl(data);

    /* Clear V-bit */
    writel_uncached(addr_val & ~PMB_V, addr);
    writel_uncached(data_val & ~PMB_V, data);
}

#ifdef CONFIG_PM
static void set_pmb_entry(struct pmb_entry *pmbe)
{
    unsigned long flags;

    raw_spin_lock_irqsave(&pmbe->lock, flags);
    __set_pmb_entry(pmbe);
    raw_spin_unlock_irqrestore(&pmbe->lock, flags);
}
#endif /* CONFIG_PM */

int pmb_bolt_mapping(unsigned long vaddr, phys_addr_t phys,
             unsigned long size, pgprot_t prot)
{
    struct pmb_entry *pmbp, *pmbe;
    unsigned long orig_addr, orig_size;
    unsigned long flags, pmb_flags;
    int i, mapped;

    if (size < SZ_16M)
        return -EINVAL;
    if (!pmb_addr_valid(vaddr, size))
        return -EFAULT;
    if (pmb_mapping_exists(vaddr, phys, size))
        return 0;

    orig_addr = vaddr;
    orig_size = size;

    flush_tlb_kernel_range(vaddr, vaddr + size);

    pmb_flags = pgprot_to_pmb_flags(prot);
    pmbp = NULL;

    do {
        for (i = mapped = 0; i < ARRAY_SIZE(pmb_sizes); i++) {
            if (size < pmb_sizes[i].size)
                continue;

            pmbe = pmb_alloc(vaddr, phys, pmb_flags |
                     pmb_sizes[i].flag, PMB_NO_ENTRY);
            if (IS_ERR(pmbe)) {
                pmb_unmap_entry(pmbp, mapped);
                return PTR_ERR(pmbe);
            }

            raw_spin_lock_irqsave(&pmbe->lock, flags);

            pmbe->size = pmb_sizes[i].size;

            __set_pmb_entry(pmbe);

            phys    += pmbe->size;
            vaddr   += pmbe->size;
            size    -= pmbe->size;

            /*
             * Link adjacent entries that span multiple PMB
             * entries for easier tear-down.
             */
            if (likely(pmbp)) {
                raw_spin_lock_nested(&pmbp->lock,
                             SINGLE_DEPTH_NESTING);
                pmbp->link = pmbe;
                raw_spin_unlock(&pmbp->lock);
            }

            pmbp = pmbe;

            /*
             * Instead of trying smaller sizes on every
             * iteration (even if we succeed in allocating
             * space), try using pmb_sizes[i].size again.
             */
            i--;
            mapped++;

            raw_spin_unlock_irqrestore(&pmbe->lock, flags);
        }
    } while (size >= SZ_16M);

    flush_cache_vmap(orig_addr, orig_addr + orig_size);

    return 0;
}

void __iomem *pmb_remap_caller(phys_addr_t phys, unsigned long size,
                   pgprot_t prot, void *caller)
{
    unsigned long vaddr;
    phys_addr_t offset, last_addr;
    phys_addr_t align_mask;
    unsigned long aligned;
    struct vm_struct *area;
    int i, ret;

    if (!pmb_iomapping_enabled)
        return NULL;

    /*
     * Small mappings need to go through the TLB.
     */
    if (size < SZ_16M)
        return ERR_PTR(-EINVAL);
    if (!pmb_prot_valid(prot))
        return ERR_PTR(-EINVAL);

    for (i = 0; i < ARRAY_SIZE(pmb_sizes); i++)
        if (size >= pmb_sizes[i].size)
            break;

    last_addr = phys + size;
    align_mask = ~(pmb_sizes[i].size - 1);
    offset = phys & ~align_mask;
    phys &= align_mask;
    aligned = ALIGN(last_addr, pmb_sizes[i].size) - phys;

    /*
     * XXX: This should really start from uncached_end, but this
     * causes the MMU to reset, so for now we restrict it to the
     * 0xb000...0xc000 range.
     */
    area = __get_vm_area_caller(aligned, VM_IOREMAP, 0xb0000000,
                    P3SEG, caller);
    if (!area)
        return NULL;

    area->phys_addr = phys;
    vaddr = (unsigned long)area->addr;

    ret = pmb_bolt_mapping(vaddr, phys, size, prot);
    if (unlikely(ret != 0))
        return ERR_PTR(ret);

    return (void __iomem *)(offset + (char *)vaddr);
}

int pmb_unmap(void __iomem *addr)
{
    struct pmb_entry *pmbe = NULL;
    unsigned long vaddr = (unsigned long __force)addr;
    int i, found = 0;

    read_lock(&pmb_rwlock);

    for (i = 0; i < ARRAY_SIZE(pmb_entry_list); i++) {
        if (test_bit(i, pmb_map)) {
            pmbe = &pmb_entry_list[i];
            if (pmbe->vpn == vaddr) {
                found = 1;
                break;
            }
        }
    }

    read_unlock(&pmb_rwlock);

    if (found) {
        pmb_unmap_entry(pmbe, NR_PMB_ENTRIES);
        return 0;
    }

    return -EINVAL;
}

static void __pmb_unmap_entry(struct pmb_entry *pmbe, int depth)
{
    do {
        struct pmb_entry *pmblink = pmbe;

        /*
         * We may be called before this pmb_entry has been
         * entered into the PMB table via set_pmb_entry(), but
         * that's OK because we've allocated a unique slot for
         * this entry in pmb_alloc() (even if we haven't filled
         * it yet).
         *
         * Therefore, calling __clear_pmb_entry() is safe as no
         * other mapping can be using that slot.
         */
        __clear_pmb_entry(pmbe);

        flush_cache_vunmap(pmbe->vpn, pmbe->vpn + pmbe->size);

        pmbe = pmblink->link;

        pmb_free(pmblink);
    } while (pmbe && --depth);
}

static void pmb_unmap_entry(struct pmb_entry *pmbe, int depth)
{
    unsigned long flags;

    if (unlikely(!pmbe))
        return;

    write_lock_irqsave(&pmb_rwlock, flags);
    __pmb_unmap_entry(pmbe, depth);
    write_unlock_irqrestore(&pmb_rwlock, flags);
}

static void __init pmb_notify(void)
{
    int i;

    pr_info("PMB: boot mappings:\n");

    read_lock(&pmb_rwlock);

    for (i = 0; i < ARRAY_SIZE(pmb_entry_list); i++) {
        struct pmb_entry *pmbe;

        if (!test_bit(i, pmb_map))
            continue;

        pmbe = &pmb_entry_list[i];

        pr_info("       0x%08lx -> 0x%08lx [ %4ldMB %2scached ]\n",
            pmbe->vpn >> PAGE_SHIFT, pmbe->ppn >> PAGE_SHIFT,
            pmbe->size >> 20, (pmbe->flags & PMB_C) ? "" : "un");
    }

    read_unlock(&pmb_rwlock);
}

/*
 * Sync our software copy of the PMB mappings with those in hardware. The
 * mappings in the hardware PMB were either set up by the bootloader or
 * very early on by the kernel.
 */
static void __init pmb_synchronize(void)
{
    struct pmb_entry *pmbp = NULL;
    int i, j;

    /*
     * Run through the initial boot mappings, log the established
     * ones, and blow away anything that falls outside of the valid
     * PPN range. Specifically, we only care about existing mappings
     * that impact the cached/uncached sections.
     *
     * Note that touching these can be a bit of a minefield; the boot
     * loader can establish multi-page mappings with the same caching
     * attributes, so we need to ensure that we aren't modifying a
     * mapping that we're presently executing from, or may execute
     * from in the case of straddling page boundaries.
     *
     * In the future we will have to tidy up after the boot loader by
     * jumping between the cached and uncached mappings and tearing
     * down alternating mappings while executing from the other.
     */
    for (i = 0; i < NR_PMB_ENTRIES; i++) {
        unsigned long addr, data;
        unsigned long addr_val, data_val;
        unsigned long ppn, vpn, flags;
        unsigned long irqflags;
        unsigned int size;
        struct pmb_entry *pmbe;

        addr = mk_pmb_addr(i);
        data = mk_pmb_data(i);

        addr_val = __raw_readl(addr);
        data_val = __raw_readl(data);

        /*
         * Skip over any bogus entries
         */
        if (!(data_val & PMB_V) || !(addr_val & PMB_V))
            continue;

        ppn = data_val & PMB_PFN_MASK;
        vpn = addr_val & PMB_PFN_MASK;

        /*
         * Only preserve in-range mappings.
         */
        if (!pmb_ppn_in_range(ppn)) {
            /*
             * Invalidate anything out of bounds.
             */
            writel_uncached(addr_val & ~PMB_V, addr);
            writel_uncached(data_val & ~PMB_V, data);
            continue;
        }

        /*
         * Update the caching attributes if necessary
         */
        if (data_val & PMB_C) {
            data_val &= ~PMB_CACHE_MASK;
            data_val |= pmb_cache_flags();

            writel_uncached(data_val, data);
        }

        size = data_val & PMB_SZ_MASK;
        flags = size | (data_val & PMB_CACHE_MASK);

        pmbe = pmb_alloc(vpn, ppn, flags, i);
        if (IS_ERR(pmbe)) {
            WARN_ON_ONCE(1);
            continue;
        }

        raw_spin_lock_irqsave(&pmbe->lock, irqflags);

        for (j = 0; j < ARRAY_SIZE(pmb_sizes); j++)
            if (pmb_sizes[j].flag == size)
                pmbe->size = pmb_sizes[j].size;

        if (pmbp) {
            raw_spin_lock_nested(&pmbp->lock, SINGLE_DEPTH_NESTING);
            /*
             * Compare the previous entry against the current one to
             * see if the entries span a contiguous mapping. If so,
             * setup the entry links accordingly. Compound mappings
             * are later coalesced.
             */
            if (pmb_can_merge(pmbp, pmbe))
                pmbp->link = pmbe;
            raw_spin_unlock(&pmbp->lock);
        }

        pmbp = pmbe;

        raw_spin_unlock_irqrestore(&pmbe->lock, irqflags);
    }
}

static void __init pmb_merge(struct pmb_entry *head)
{
    unsigned long span, newsize;
    struct pmb_entry *tail;
    int i = 1, depth = 0;

    span = newsize = head->size;

    tail = head->link;
    while (tail) {
        span += tail->size;

        if (pmb_size_valid(span)) {
            newsize = span;
            depth = i;
        }

        /* This is the end of the line.. */
        if (!tail->link)
            break;

        tail = tail->link;
        i++;
    }

    /*
     * The merged page size must be valid.
     */
    if (!depth || !pmb_size_valid(newsize))
        return;

    head->flags &= ~PMB_SZ_MASK;
    head->flags |= pmb_size_to_flags(newsize);

    head->size = newsize;

    __pmb_unmap_entry(head->link, depth);
    __set_pmb_entry(head);
}

static void __init pmb_coalesce(void)
{
    unsigned long flags;
    int i;

    write_lock_irqsave(&pmb_rwlock, flags);

    for (i = 0; i < ARRAY_SIZE(pmb_entry_list); i++) {
        struct pmb_entry *pmbe;

        if (!test_bit(i, pmb_map))
            continue;

        pmbe = &pmb_entry_list[i];

        /*
         * We're only interested in compound mappings
         */
        if (!pmbe->link)
            continue;

        /*
         * Nothing to do if it already uses the largest possible
         * page size.
         */
        if (pmbe->size == SZ_512M)
            continue;

        pmb_merge(pmbe);
    }

    write_unlock_irqrestore(&pmb_rwlock, flags);
}

#ifdef CONFIG_UNCACHED_MAPPING
static void __init pmb_resize(void)
{
    int i;

    /*
     * If the uncached mapping was constructed by the kernel, it will
     * already be a reasonable size.
     */
    if (uncached_size == SZ_16M)
        return;

    read_lock(&pmb_rwlock);

    for (i = 0; i < ARRAY_SIZE(pmb_entry_list); i++) {
        struct pmb_entry *pmbe;
        unsigned long flags;

        if (!test_bit(i, pmb_map))
            continue;

        pmbe = &pmb_entry_list[i];

        if (pmbe->vpn != uncached_start)
            continue;

        /*
         * Found it, now resize it.
         */
        raw_spin_lock_irqsave(&pmbe->lock, flags);

        pmbe->size = SZ_16M;
        pmbe->flags &= ~PMB_SZ_MASK;
        pmbe->flags |= pmb_size_to_flags(pmbe->size);

        uncached_resize(pmbe->size);

        __set_pmb_entry(pmbe);

        raw_spin_unlock_irqrestore(&pmbe->lock, flags);
    }

    read_unlock(&pmb_rwlock);
}
#endif

static int __init early_pmb(char *p)
{
    if (!p)
        return 0;

    if (strstr(p, "iomap"))
        pmb_iomapping_enabled = 1;

    return 0;
}
early_param("pmb", early_pmb);

void __init pmb_init(void)
{
    /* Synchronize software state */
    pmb_synchronize();

    /* Attempt to combine compound mappings */
    pmb_coalesce();

#ifdef CONFIG_UNCACHED_MAPPING
    /* Resize initial mappings, if necessary */
    pmb_resize();
#endif

    /* Log them */
    pmb_notify();

    writel_uncached(0, PMB_IRMCR);

    /* Flush out the TLB */
    local_flush_tlb_all();
    ctrl_barrier();
}

bool __in_29bit_mode(void)
{
        return (__raw_readl(PMB_PASCR) & PASCR_SE) == 0;
}

static int pmb_seq_show(struct seq_file *file, void *iter)
{
    int i;

    seq_printf(file, "V: Valid, C: Cacheable, WT: Write-Through\n"
             "CB: Copy-Back, B: Buffered, UB: Unbuffered\n");
    seq_printf(file, "ety   vpn  ppn  size   flags\n");

    for (i = 0; i < NR_PMB_ENTRIES; i++) {
        unsigned long addr, data;
        unsigned int size;
        char *sz_str = NULL;

        addr = __raw_readl(mk_pmb_addr(i));
        data = __raw_readl(mk_pmb_data(i));

        size = data & PMB_SZ_MASK;
        sz_str = (size == PMB_SZ_16M)  ? " 16MB":
             (size == PMB_SZ_64M)  ? " 64MB":
             (size == PMB_SZ_128M) ? "128MB":
                             "512MB";

        /* 02: V 0x88 0x08 128MB C CB  B */
        seq_printf(file, "%02d: %c 0x%02lx 0x%02lx %s %c %s %s\n",
               i, ((addr & PMB_V) && (data & PMB_V)) ? 'V' : ' ',
               (addr >> 24) & 0xff, (data >> 24) & 0xff,
               sz_str, (data & PMB_C) ? 'C' : ' ',
               (data & PMB_WT) ? "WT" : "CB",
               (data & PMB_UB) ? "UB" : " B");
    }

    return 0;
}

static int pmb_debugfs_open(struct inode *inode, struct file *file)
{
    return single_open(file, pmb_seq_show, NULL);
}

static const struct file_operations pmb_debugfs_fops = {
    .owner      = THIS_MODULE,
    .open       = pmb_debugfs_open,
    .read       = seq_read,
    .llseek     = seq_lseek,
    .release    = single_release,
};

static int __init pmb_debugfs_init(void)
{
    struct dentry *dentry;

    dentry = debugfs_create_file("pmb", S_IFREG | S_IRUGO,
                     arch_debugfs_dir, NULL, &pmb_debugfs_fops);
    if (!dentry)
        return -ENOMEM;

    return 0;
}
subsys_initcall(pmb_debugfs_init);

#ifdef CONFIG_PM
static void pmb_syscore_resume(void)
{
    struct pmb_entry *pmbe;
    int i;

    read_lock(&pmb_rwlock);

    for (i = 0; i < ARRAY_SIZE(pmb_entry_list); i++) {
        if (test_bit(i, pmb_map)) {
            pmbe = &pmb_entry_list[i];
            set_pmb_entry(pmbe);
        }
    }

    read_unlock(&pmb_rwlock);
}

static struct syscore_ops pmb_syscore_ops = {
    .resume = pmb_syscore_resume,
};

static int __init pmb_sysdev_init(void)
{
    register_syscore_ops(&pmb_syscore_ops);
    return 0;
}
subsys_initcall(pmb_sysdev_init);
#endif