sq.c

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/*
 * arch/sh/kernel/cpu/sh4/sq.c
 *
 * General management API for SH-4 integrated Store Queues
 *
 * Copyright (C) 2001 - 2006  Paul Mundt
 * Copyright (C) 2001, 2002  M. R. Brown
 *
 * 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/cpu.h>
#include <linux/bitmap.h>
#include <linux/device.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/vmalloc.h>
#include <linux/mm.h>
#include <linux/io.h>
#include <linux/prefetch.h>
#include <asm/page.h>
#include <asm/cacheflush.h>
#include <cpu/sq.h>

struct sq_mapping;

struct sq_mapping {
    const char *name;

    unsigned long sq_addr;
    unsigned long addr;
    unsigned int size;

    struct sq_mapping *next;
};

static struct sq_mapping *sq_mapping_list;
static DEFINE_SPINLOCK(sq_mapping_lock);
static struct kmem_cache *sq_cache;
static unsigned long *sq_bitmap;

#define store_queue_barrier()           \
do {                        \
    (void)__raw_readl(P4SEG_STORE_QUE); \
    __raw_writel(0, P4SEG_STORE_QUE + 0);   \
    __raw_writel(0, P4SEG_STORE_QUE + 8);   \
} while (0);

void sq_flush_range(unsigned long start, unsigned int len)
{
    unsigned long *sq = (unsigned long *)start;

    /* Flush the queues */
    for (len >>= 5; len--; sq += 8)
        prefetchw(sq);

    /* Wait for completion */
    store_queue_barrier();
}
EXPORT_SYMBOL(sq_flush_range);

static inline void sq_mapping_list_add(struct sq_mapping *map)
{
    struct sq_mapping **p, *tmp;

    spin_lock_irq(&sq_mapping_lock);

    p = &sq_mapping_list;
    while ((tmp = *p) != NULL)
        p = &tmp->next;

    map->next = tmp;
    *p = map;

    spin_unlock_irq(&sq_mapping_lock);
}

static inline void sq_mapping_list_del(struct sq_mapping *map)
{
    struct sq_mapping **p, *tmp;

    spin_lock_irq(&sq_mapping_lock);

    for (p = &sq_mapping_list; (tmp = *p); p = &tmp->next)
        if (tmp == map) {
            *p = tmp->next;
            break;
        }

    spin_unlock_irq(&sq_mapping_lock);
}

static int __sq_remap(struct sq_mapping *map, pgprot_t prot)
{
#if defined(CONFIG_MMU)
    struct vm_struct *vma;

    vma = __get_vm_area(map->size, VM_ALLOC, map->sq_addr, SQ_ADDRMAX);
    if (!vma)
        return -ENOMEM;

    vma->phys_addr = map->addr;

    if (ioremap_page_range((unsigned long)vma->addr,
                   (unsigned long)vma->addr + map->size,
                   vma->phys_addr, prot)) {
        vunmap(vma->addr);
        return -EAGAIN;
    }
#else
    /*
     * Without an MMU (or with it turned off), this is much more
     * straightforward, as we can just load up each queue's QACR with
     * the physical address appropriately masked.
     */
    __raw_writel(((map->addr >> 26) << 2) & 0x1c, SQ_QACR0);
    __raw_writel(((map->addr >> 26) << 2) & 0x1c, SQ_QACR1);
#endif

    return 0;
}

unsigned long sq_remap(unsigned long phys, unsigned int size,
               const char *name, pgprot_t prot)
{
    struct sq_mapping *map;
    unsigned long end;
    unsigned int psz;
    int ret, page;

    /* Don't allow wraparound or zero size */
    end = phys + size - 1;
    if (unlikely(!size || end < phys))
        return -EINVAL;
    /* Don't allow anyone to remap normal memory.. */
    if (unlikely(phys < virt_to_phys(high_memory)))
        return -EINVAL;

    phys &= PAGE_MASK;
    size = PAGE_ALIGN(end + 1) - phys;

    map = kmem_cache_alloc(sq_cache, GFP_KERNEL);
    if (unlikely(!map))
        return -ENOMEM;

    map->addr = phys;
    map->size = size;
    map->name = name;

    page = bitmap_find_free_region(sq_bitmap, 0x04000000 >> PAGE_SHIFT,
                       get_order(map->size));
    if (unlikely(page < 0)) {
        ret = -ENOSPC;
        goto out;
    }

    map->sq_addr = P4SEG_STORE_QUE + (page << PAGE_SHIFT);

    ret = __sq_remap(map, prot);
    if (unlikely(ret != 0))
        goto out;

    psz = (size + (PAGE_SIZE - 1)) >> PAGE_SHIFT;
    pr_info("sqremap: %15s  [%4d page%s]  va 0x%08lx   pa 0x%08lx\n",
        likely(map->name) ? map->name : "???",
        psz, psz == 1 ? " " : "s",
        map->sq_addr, map->addr);

    sq_mapping_list_add(map);

    return map->sq_addr;

out:
    kmem_cache_free(sq_cache, map);
    return ret;
}
EXPORT_SYMBOL(sq_remap);

void sq_unmap(unsigned long vaddr)
{
    struct sq_mapping **p, *map;
    int page;

    for (p = &sq_mapping_list; (map = *p); p = &map->next)
        if (map->sq_addr == vaddr)
            break;

    if (unlikely(!map)) {
        printk("%s: bad store queue address 0x%08lx\n",
               __func__, vaddr);
        return;
    }

    page = (map->sq_addr - P4SEG_STORE_QUE) >> PAGE_SHIFT;
    bitmap_release_region(sq_bitmap, page, get_order(map->size));

#ifdef CONFIG_MMU
    {
        /*
         * Tear down the VMA in the MMU case.
         */
        struct vm_struct *vma;

        vma = remove_vm_area((void *)(map->sq_addr & PAGE_MASK));
        if (!vma) {
            printk(KERN_ERR "%s: bad address 0x%08lx\n",
                   __func__, map->sq_addr);
            return;
        }
    }
#endif

    sq_mapping_list_del(map);

    kmem_cache_free(sq_cache, map);
}
EXPORT_SYMBOL(sq_unmap);

/*
 * Needlessly complex sysfs interface. Unfortunately it doesn't seem like
 * there is any other easy way to add things on a per-cpu basis without
 * putting the directory entries somewhere stupid and having to create
 * links in sysfs by hand back in to the per-cpu directories.
 *
 * Some day we may want to have an additional abstraction per store
 * queue, but considering the kobject hell we already have to deal with,
 * it's simply not worth the trouble.
 */
static struct kobject *sq_kobject[NR_CPUS];

struct sq_sysfs_attr {
    struct attribute attr;
    ssize_t (*show)(char *buf);
    ssize_t (*store)(const char *buf, size_t count);
};

#define to_sq_sysfs_attr(a) container_of(a, struct sq_sysfs_attr, attr)

static ssize_t sq_sysfs_show(struct kobject *kobj, struct attribute *attr,
                 char *buf)
{
    struct sq_sysfs_attr *sattr = to_sq_sysfs_attr(attr);

    if (likely(sattr->show))
        return sattr->show(buf);

    return -EIO;
}

static ssize_t sq_sysfs_store(struct kobject *kobj, struct attribute *attr,
                  const char *buf, size_t count)
{
    struct sq_sysfs_attr *sattr = to_sq_sysfs_attr(attr);

    if (likely(sattr->store))
        return sattr->store(buf, count);

    return -EIO;
}

static ssize_t mapping_show(char *buf)
{
    struct sq_mapping **list, *entry;
    char *p = buf;

    for (list = &sq_mapping_list; (entry = *list); list = &entry->next)
        p += sprintf(p, "%08lx-%08lx [%08lx]: %s\n",
                 entry->sq_addr, entry->sq_addr + entry->size,
                 entry->addr, entry->name);

    return p - buf;
}

static ssize_t mapping_store(const char *buf, size_t count)
{
    unsigned long base = 0, len = 0;

    sscanf(buf, "%lx %lx", &base, &len);
    if (!base)
        return -EIO;

    if (likely(len)) {
        int ret = sq_remap(base, len, "Userspace", PAGE_SHARED);
        if (ret < 0)
            return ret;
    } else
        sq_unmap(base);

    return count;
}

static struct sq_sysfs_attr mapping_attr =
    __ATTR(mapping, 0644, mapping_show, mapping_store);

static struct attribute *sq_sysfs_attrs[] = {
    &mapping_attr.attr,
    NULL,
};

static const struct sysfs_ops sq_sysfs_ops = {
    .show   = sq_sysfs_show,
    .store  = sq_sysfs_store,
};

static struct kobj_type ktype_percpu_entry = {
    .sysfs_ops  = &sq_sysfs_ops,
    .default_attrs  = sq_sysfs_attrs,
};

static int sq_dev_add(struct device *dev, struct subsys_interface *sif)
{
    unsigned int cpu = dev->id;
    struct kobject *kobj;
    int error;

    sq_kobject[cpu] = kzalloc(sizeof(struct kobject), GFP_KERNEL);
    if (unlikely(!sq_kobject[cpu]))
        return -ENOMEM;

    kobj = sq_kobject[cpu];
    error = kobject_init_and_add(kobj, &ktype_percpu_entry, &dev->kobj,
                     "%s", "sq");
    if (!error)
        kobject_uevent(kobj, KOBJ_ADD);
    return error;
}

static int sq_dev_remove(struct device *dev, struct subsys_interface *sif)
{
    unsigned int cpu = dev->id;
    struct kobject *kobj = sq_kobject[cpu];

    kobject_put(kobj);
    return 0;
}

static struct subsys_interface sq_interface = {
    .name       = "sq",
    .subsys     = &cpu_subsys,
    .add_dev    = sq_dev_add,
    .remove_dev = sq_dev_remove,
};

static int __init sq_api_init(void)
{
    unsigned int nr_pages = 0x04000000 >> PAGE_SHIFT;
    unsigned int size = (nr_pages + (BITS_PER_LONG - 1)) / BITS_PER_LONG;
    int ret = -ENOMEM;

    printk(KERN_NOTICE "sq: Registering store queue API.\n");

    sq_cache = kmem_cache_create("store_queue_cache",
                sizeof(struct sq_mapping), 0, 0, NULL);
    if (unlikely(!sq_cache))
        return ret;

    sq_bitmap = kzalloc(size, GFP_KERNEL);
    if (unlikely(!sq_bitmap))
        goto out;

    ret = subsys_interface_register(&sq_interface);
    if (unlikely(ret != 0))
        goto out;

    return 0;

out:
    kfree(sq_bitmap);
    kmem_cache_destroy(sq_cache);

    return ret;
}

static void __exit sq_api_exit(void)
{
    subsys_interface_unregister(&sq_interface);
    kfree(sq_bitmap);
    kmem_cache_destroy(sq_cache);
}

module_init(sq_api_init);
module_exit(sq_api_exit);

MODULE_AUTHOR("Paul Mundt <[email protected]>, M. R. Brown <[email protected]>");
MODULE_DESCRIPTION("Simple API for SH-4 integrated Store Queues");
MODULE_LICENSE("GPL");