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sq.c

/*
 * 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/sysdev.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 <asm/page.h>
#include <asm/cacheflush.h>
#include <asm/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)ctrl_inl(P4SEG_STORE_QUE);    \
      ctrl_outl(0, P4SEG_STORE_QUE + 0);  \
      ctrl_outl(0, P4SEG_STORE_QUE + 8);  \
} while (0);

/**
 * sq_flush_range - Flush (prefetch) a specific SQ range
 * @start: the store queue address to start flushing from
 * @len: the length to flush
 *
 * Flushes the store queue cache from @start to @start + @len in a
 * linear fashion.
 */
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, unsigned long flags)
{
#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, __pgprot(flags))) {
            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.
       */
      ctrl_outl(((map->addr >> 26) << 2) & 0x1c, SQ_QACR0);
      ctrl_outl(((map->addr >> 26) << 2) & 0x1c, SQ_QACR1);
#endif

      return 0;
}

/**
 * sq_remap - Map a physical address through the Store Queues
 * @phys: Physical address of mapping.
 * @size: Length of mapping.
 * @name: User invoking mapping.
 * @flags: Protection flags.
 *
 * Remaps the physical address @phys through the next available store queue
 * address of @size length. @name is logged at boot time as well as through
 * the sysfs interface.
 */
unsigned long sq_remap(unsigned long phys, unsigned int size,
                   const char *name, unsigned long flags)
{
      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, pgprot_val(PAGE_KERNEL_NOCACHE) | flags);
      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);

/**
 * sq_unmap - Unmap a Store Queue allocation
 * @map: Pre-allocated Store Queue mapping.
 *
 * Unmaps the store queue allocation @map that was previously created by
 * sq_remap(). Also frees up the pte that was previously inserted into
 * the kernel page table and discards the UTLB translation.
 */
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",
                   __FUNCTION__, 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",
                         __FUNCTION__, 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(attr)      container_of(attr, 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",
                           pgprot_val(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 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 __devinit sq_sysdev_add(struct sys_device *sysdev)
{
      unsigned int cpu = sysdev->id;
      struct kobject *kobj;

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

      kobj = sq_kobject[cpu];
      kobj->parent = &sysdev->kobj;
      kobject_set_name(kobj, "%s", "sq");
      kobj->ktype = &ktype_percpu_entry;

      return kobject_register(kobj);
}

static int __devexit sq_sysdev_remove(struct sys_device *sysdev)
{
      unsigned int cpu = sysdev->id;
      struct kobject *kobj = sq_kobject[cpu];

      kobject_unregister(kobj);
      return 0;
}

static struct sysdev_driver sq_sysdev_driver = {
      .add        = sq_sysdev_add,
      .remove           = __devexit_p(sq_sysdev_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 = sysdev_driver_register(&cpu_sysdev_class, &sq_sysdev_driver);
      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)
{
      sysdev_driver_unregister(&cpu_sysdev_class, &sq_sysdev_driver);
      kfree(sq_bitmap);
      kmem_cache_destroy(sq_cache);
}

module_init(sq_api_init);
module_exit(sq_api_exit);

MODULE_AUTHOR("Paul Mundt <lethal@linux-sh.org>, M. R. Brown <mrbrown@0xd6.org>");
MODULE_DESCRIPTION("Simple API for SH-4 integrated Store Queues");
MODULE_LICENSE("GPL");

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