/*
 *      memrar_handler 1.0:  An Intel restricted access region handler device
 *
 *      Copyright (C) 2010 Intel Corporation. All rights reserved.
 *
 *      This program is free software; you can redistribute it and/or
 *      modify it under the terms of version 2 of the GNU General
 *      Public License as published by the Free Software Foundation.
 *
 *      This program is distributed in the hope that it will be
 *      useful, but WITHOUT ANY WARRANTY; without even the implied
 *      warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
 *      PURPOSE.  See the GNU General Public License for more details.
 *      You should have received a copy of the GNU General Public
 *      License along with this program; if not, write to the Free
 *      Software Foundation, Inc., 59 Temple Place - Suite 330,
 *      Boston, MA  02111-1307, USA.
 *      The full GNU General Public License is included in this
 *      distribution in the file called COPYING.
 *
 * -------------------------------------------------------------------
 *
 *      Moorestown restricted access regions (RAR) provide isolated
 *      areas of main memory that are only acceessible by authorized
 *      devices.
 *
 *      The Intel Moorestown RAR handler module exposes a kernel space
 *      RAR memory management mechanism.  It is essentially a
 *      RAR-specific allocator.
 *
 *      Besides providing RAR buffer management, the RAR handler also
 *      behaves in many ways like an OS virtual memory manager.  For
 *      example, the RAR "handles" created by the RAR handler are
 *      analogous to user space virtual addresses.
 *
 *      RAR memory itself is never accessed directly by the RAR
 *      handler.
 */

#include <linux/miscdevice.h>
#include <linux/fs.h>
#include <linux/slab.h>
#include <linux/kref.h>
#include <linux/mutex.h>
#include <linux/kernel.h>
#include <linux/uaccess.h>
#include <linux/mm.h>
#include <linux/ioport.h>
#include <linux/io.h>
#include <linux/rar_register.h>

#include "memrar.h"
#include "memrar_allocator.h"


#define MEMRAR_VER "1.0"

/*
 * Moorestown supports three restricted access regions.
 *
 * We only care about the first two, video and audio.  The third,
 * reserved for Chaabi and the P-unit, will be handled by their
 * respective drivers.
 */
#define MRST_NUM_RAR 2

/* ---------------- -------------------- ------------------- */

/**
 * struct memrar_buffer_info - struct that keeps track of all RAR buffers
 * @list:       Linked list of memrar_buffer_info objects.
 * @buffer:     Core RAR buffer information.
 * @refcount:   Reference count.
 * @owner:      File handle corresponding to process that reserved the
 *              block of memory in RAR.  This will be zero for buffers
 *              allocated by other drivers instead of by a user space
 *              process.
 *
 * This structure encapsulates a link list of RAR buffers, as well as
 * other characteristics specific to a given list node, such as the
 * reference count on the corresponding RAR buffer.
 */
struct memrar_buffer_info {
        struct list_head list;
        struct RAR_buffer buffer;
        struct kref refcount;
        struct file *owner;
};

/**
 * struct memrar_rar_info - characteristics of a given RAR
 * @base:       Base bus address of the RAR.
 * @length:     Length of the RAR.
 * @iobase:     Virtual address of RAR mapped into kernel.
 * @allocator:  Allocator associated with the RAR.  Note the allocator
 *              "capacity" may be smaller than the RAR length if the
 *              length is not a multiple of the configured allocator
 *              block size.
 * @buffers:    Table that keeps track of all reserved RAR buffers.
 * @lock:       Lock used to synchronize access to RAR-specific data
 *              structures.
 *
 * Each RAR has an associated memrar_rar_info structure that describes
 * where in memory the RAR is located, how large it is, and a list of
 * reserved RAR buffers inside that RAR.  Each RAR also has a mutex
 * associated with it to reduce lock contention when operations on
 * multiple RARs are performed in parallel.
 */
struct memrar_rar_info {
        dma_addr_t base;
        unsigned long length;
        void __iomem *iobase;
        struct memrar_allocator *allocator;
        struct memrar_buffer_info buffers;
        struct mutex lock;
        int allocated;  /* True if we own this RAR */
};

/*
 * Array of RAR characteristics.
 */
static struct memrar_rar_info memrars[MRST_NUM_RAR];

/* ---------------- -------------------- ------------------- */

/* Validate RAR type. */
static inline int memrar_is_valid_rar_type(u32 type)
{
        return type == RAR_TYPE_VIDEO || type == RAR_TYPE_AUDIO;
}

/* Check if an address/handle falls with the given RAR memory range. */
static inline int memrar_handle_in_range(struct memrar_rar_info *rar,
                                         u32 vaddr)
{
        unsigned long const iobase = (unsigned long) (rar->iobase);
        return (vaddr >= iobase && vaddr < iobase + rar->length);
}

/* Retrieve RAR information associated with the given handle. */
static struct memrar_rar_info *memrar_get_rar_info(u32 vaddr)
{
        int i;
        for (i = 0; i < MRST_NUM_RAR; ++i) {
                struct memrar_rar_info * const rar = &memrars[i];
                if (memrar_handle_in_range(rar, vaddr))
                        return rar;
        }

        return NULL;
}

/**
 *      memrar_get_bus address          -       handle to bus address
 *
 *      Retrieve bus address from given handle.
 *
 *      Returns address corresponding to given handle.  Zero if handle is
 *      invalid.
 */
static dma_addr_t memrar_get_bus_address(
        struct memrar_rar_info *rar,
        u32 vaddr)
{
        unsigned long const iobase = (unsigned long) (rar->iobase);

        if (!memrar_handle_in_range(rar, vaddr))
                return 0;

        /*
         * An assumption is made that the virtual address offset is
         * the same as the bus address offset, at least based on the
         * way this driver is implemented.  For example, vaddr + 2 ==
         * baddr + 2.
         *
         * @todo Is that a valid assumption?
         */
        return rar->base + (vaddr - iobase);
}

/**
 *      memrar_get_physical_address     -       handle to physical address
 *
 *      Retrieve physical address from given handle.
 *
 *      Returns address corresponding to given handle.  Zero if handle is
 *      invalid.
 */
static dma_addr_t memrar_get_physical_address(
        struct memrar_rar_info *rar,
        u32 vaddr)
{
        /*
         * @todo This assumes that the bus address and physical
         *       address are the same.  That is true for Moorestown
         *       but not necessarily on other platforms.  This
         *       deficiency should be addressed at some point.
         */
        return memrar_get_bus_address(rar, vaddr);
}

/**
 *      memrar_release_block    -       release a block to the pool
 *      @kref: kref of block
 *
 *      Core block release code. A node has hit zero references so can
 *      be released and the lists must be updated.
 *
 *      Note: This code removes the node from a list.  Make sure any list
 *      iteration is performed using list_for_each_safe().
 */
static void memrar_release_block_i(struct kref *ref)
{
        /*
         * Last reference is being released.  Remove from the table,
         * and reclaim resources.
         */

        struct memrar_buffer_info * const node =
                container_of(ref, struct memrar_buffer_info, refcount);

        struct RAR_block_info * const user_info =
                &node->buffer.info;

        struct memrar_allocator * const allocator =
                memrars[user_info->type].allocator;

        list_del(&node->list);

        memrar_allocator_free(allocator, user_info->handle);

        kfree(node);
}

/**
 *      memrar_init_rar_resources       -       configure a RAR
 *      @rarnum: rar that has been allocated
 *      @devname: name of our device
 *
 *      Initialize RAR parameters, such as bus addresses, etc and make
 *      the resource accessible.
 */
static int memrar_init_rar_resources(int rarnum, char const *devname)
{
        /* ---- Sanity Checks ----
         * 1. RAR bus addresses in both Lincroft and Langwell RAR
         *    registers should be the same.
         *    a. There's no way we can do this through IA.
         *
         * 2. Secure device ID in Langwell RAR registers should be set
         *    appropriately, e.g. only LPE DMA for the audio RAR, and
         *    security for the other Langwell based RAR registers.
         *    a. There's no way we can do this through IA.
         *
         * 3. Audio and video RAR registers and RAR access should be
         *    locked down.  If not, enable RAR access control.  Except
         *    for debugging purposes, there is no reason for them to
         *    be unlocked.
         *    a.  We can only do this for the Lincroft (IA) side.
         *
         * @todo Should the RAR handler driver even be aware of audio
         *       and video RAR settings?
         */

        /*
         * RAR buffer block size.
         *
         * We choose it to be the size of a page to simplify the
         * /dev/memrar mmap() implementation and usage.  Otherwise
         * paging is not involved once an RAR is locked down.
         */
        static size_t const RAR_BLOCK_SIZE = PAGE_SIZE;

        dma_addr_t low, high;
        struct memrar_rar_info * const rar = &memrars[rarnum];

        BUG_ON(MRST_NUM_RAR != ARRAY_SIZE(memrars));
        BUG_ON(!memrar_is_valid_rar_type(rarnum));
        BUG_ON(rar->allocated);

        if (rar_get_address(rarnum, &low, &high) != 0)
                /* No RAR is available. */
                return -ENODEV;

        if (low == 0 || high == 0) {
                rar->base      = 0;
                rar->length    = 0;
                rar->iobase    = NULL;
                rar->allocator = NULL;
                return -ENOSPC;
        }

        /*
         * @todo Verify that LNC and LNW RAR register contents
         *       addresses, security, etc are compatible and
         *       consistent).
         */

        rar->length = high - low + 1;

        /* Claim RAR memory as our own. */
        if (request_mem_region(low, rar->length, devname) == NULL) {
                rar->length = 0;
                pr_err("%s: Unable to claim RAR[%d] memory.\n",
                       devname, rarnum);
                pr_err("%s: RAR[%d] disabled.\n", devname, rarnum);
                return -EBUSY;
        }

        rar->base = low;

        /*
         * Now map it into the kernel address space.
         *
         * Note that the RAR memory may only be accessed by IA
         * when debugging.  Otherwise attempts to access the
         * RAR memory when it is locked down will result in
         * behavior similar to writing to /dev/null and
         * reading from /dev/zero.  This behavior is enforced
         * by the hardware.  Even if we don't access the
         * memory, mapping it into the kernel provides us with
         * a convenient RAR handle to bus address mapping.
         */
        rar->iobase = ioremap_nocache(rar->base, rar->length);
        if (rar->iobase == NULL) {
                pr_err("%s: Unable to map RAR memory.\n", devname);
                release_mem_region(low, rar->length);
                return -ENOMEM;
        }

        /* Initialize corresponding memory allocator. */
        rar->allocator = memrar_create_allocator((unsigned long) rar->iobase,
                                                rar->length, RAR_BLOCK_SIZE);
        if (rar->allocator == NULL) {
                iounmap(rar->iobase);
                release_mem_region(low, rar->length);
                return -ENOMEM;
        }

        pr_info("%s: BRAR[%d] bus address range = [0x%lx, 0x%lx]\n",
                devname, rarnum, (unsigned long) low, (unsigned long) high);

        pr_info("%s: BRAR[%d] size = %zu KiB\n",
                        devname, rarnum, rar->allocator->capacity / 1024);

        rar->allocated = 1;
        return 0;
}

/**
 *      memrar_fini_rar_resources       -       free up RAR resources
 *
 *      Finalize RAR resources. Free up the resource tables, hand the memory
 *      back to the kernel, unmap the device and release the address space.
 */
static void memrar_fini_rar_resources(void)
{
        int z;
        struct memrar_buffer_info *pos;
        struct memrar_buffer_info *tmp;

        /*
         * @todo Do we need to hold a lock at this point in time?
         *       (module initialization failure or exit?)
         */

        for (z = MRST_NUM_RAR; z-- != 0; ) {
                struct memrar_rar_info * const rar = &memrars[z];

                if (!rar->allocated)
                        continue;

                /* Clean up remaining resources. */

                list_for_each_entry_safe(pos,
                                         tmp,
                                         &rar->buffers.list,
                                         list) {
                        kref_put(&pos->refcount, memrar_release_block_i);
                }

                memrar_destroy_allocator(rar->allocator);
                rar->allocator = NULL;

                iounmap(rar->iobase);
                release_mem_region(rar->base, rar->length);

                rar->iobase = NULL;
                rar->base = 0;
                rar->length = 0;

                unregister_rar(z);
        }
}

/**
 *      memrar_reserve_block    -       handle an allocation request
 *      @request: block being requested
 *      @filp: owner it is tied to
 *
 *      Allocate a block of the requested RAR. If successful return the
 *      request object filled in and zero, if not report an error code
 */

static long memrar_reserve_block(struct RAR_buffer *request,
                                 struct file *filp)
{
        struct RAR_block_info * const rinfo = &request->info;
        struct RAR_buffer *buffer;
        struct memrar_buffer_info *buffer_info;
        u32 handle;
        struct memrar_rar_info *rar = NULL;

        /* Prevent array overflow. */
        if (!memrar_is_valid_rar_type(rinfo->type))
                return -EINVAL;

        rar = &memrars[rinfo->type];
        if (!rar->allocated)
                return -ENODEV;

        /* Reserve memory in RAR. */
        handle = memrar_allocator_alloc(rar->allocator, rinfo->size);
        if (handle == 0)
                return -ENOMEM;

        buffer_info = kmalloc(sizeof(*buffer_info), GFP_KERNEL);

        if (buffer_info == NULL) {
                memrar_allocator_free(rar->allocator, handle);
                return -ENOMEM;
        }

        buffer = &buffer_info->buffer;
        buffer->info.type = rinfo->type;
        buffer->info.size = rinfo->size;

        /* Memory handle corresponding to the bus address. */
        buffer->info.handle = handle;
        buffer->bus_address = memrar_get_bus_address(rar, handle);

        /*
         * Keep track of owner so that we can later cleanup if
         * necessary.
         */
        buffer_info->owner = filp;

        kref_init(&buffer_info->refcount);

        mutex_lock(&rar->lock);
        list_add(&buffer_info->list, &rar->buffers.list);
        mutex_unlock(&rar->lock);

        rinfo->handle = buffer->info.handle;
        request->bus_address = buffer->bus_address;

        return 0;
}

/**
 *      memrar_release_block            -       release a RAR block
 *      @addr: address in RAR space
 *
 *      Release a previously allocated block. Releases act on complete
 *      blocks, partially freeing a block is not supported
 */

static long memrar_release_block(u32 addr)
{
        struct memrar_buffer_info *pos;
        struct memrar_buffer_info *tmp;
        struct memrar_rar_info * const rar = memrar_get_rar_info(addr);
        long result = -EINVAL;

        if (rar == NULL)
                return -ENOENT;

        mutex_lock(&rar->lock);

        /*
         * Iterate through the buffer list to find the corresponding
         * buffer to be released.
         */
        list_for_each_entry_safe(pos,
                                 tmp,
                                 &rar->buffers.list,
                                 list) {
                struct RAR_block_info * const info =
                        &pos->buffer.info;

                /*
                 * Take into account handle offsets that may have been
                 * added to the base handle, such as in the following
                 * scenario:
                 *
                 *     u32 handle = base + offset;
                 *     rar_handle_to_bus(handle);
                 *     rar_release(handle);
                 */
                if (addr >= info->handle
                    && addr < (info->handle + info->size)
                    && memrar_is_valid_rar_type(info->type)) {
                        kref_put(&pos->refcount, memrar_release_block_i);
                        result = 0;
                        break;
                }
        }

        mutex_unlock(&rar->lock);

        return result;
}

/**
 *      memrar_get_stats        -       read statistics for a RAR
 *      @r: statistics to be filled in
 *
 *      Returns the statistics data for the RAR, or an error code if
 *      the request cannot be completed
 */
static long memrar_get_stat(struct RAR_stat *r)
{
        struct memrar_allocator *allocator;

        if (!memrar_is_valid_rar_type(r->type))
                return -EINVAL;

        if (!memrars[r->type].allocated)
                return -ENODEV;

        allocator = memrars[r->type].allocator;

        BUG_ON(allocator == NULL);

        /*
         * Allocator capacity doesn't change over time.  No
         * need to synchronize.
         */
        r->capacity = allocator->capacity;

        mutex_lock(&allocator->lock);
        r->largest_block_size = allocator->largest_free_area;
        mutex_unlock(&allocator->lock);
        return 0;
}

/**
 *      memrar_ioctl            -       ioctl callback
 *      @filp: file issuing the request
 *      @cmd: command
 *      @arg: pointer to control information
 *
 *      Perform one of the ioctls supported by the memrar device
 */

static long memrar_ioctl(struct file *filp,
                         unsigned int cmd,
                         unsigned long arg)
{
        void __user *argp = (void __user *)arg;
        long result = 0;

        struct RAR_buffer buffer;
        struct RAR_block_info * const request = &buffer.info;
        struct RAR_stat rar_info;
        u32 rar_handle;

        switch (cmd) {
        case RAR_HANDLER_RESERVE:
                if (copy_from_user(request,
                                   argp,
                                   sizeof(*request)))
                        return -EFAULT;

                result = memrar_reserve_block(&buffer, filp);
                if (result != 0)
                        return result;

                return copy_to_user(argp, request, sizeof(*request));

        case RAR_HANDLER_RELEASE:
                if (copy_from_user(&rar_handle,
                                   argp,
                                   sizeof(rar_handle)))
                        return -EFAULT;

                return memrar_release_block(rar_handle);

        case RAR_HANDLER_STAT:
                if (copy_from_user(&rar_info,
                                   argp,
                                   sizeof(rar_info)))
                        return -EFAULT;

                /*
                 * Populate the RAR_stat structure based on the RAR
                 * type given by the user
                 */
                if (memrar_get_stat(&rar_info) != 0)
                        return -EINVAL;

                /*
                 * @todo Do we need to verify destination pointer
                 *       "argp" is non-zero?  Is that already done by
                 *       copy_to_user()?
                 */
                return copy_to_user(argp,
                                    &rar_info,
                                    sizeof(rar_info)) ? -EFAULT : 0;

        default:
                return -ENOTTY;
        }

        return 0;
}

/**
 *      memrar_mmap             -       mmap helper for deubgging
 *      @filp: handle doing the mapping
 *      @vma: memory area
 *
 *      Support the mmap operation on the RAR space for debugging systems
 *      when the memory is not locked down.
 */

static int memrar_mmap(struct file *filp, struct vm_area_struct *vma)
{
        /*
         * This mmap() implementation is predominantly useful for
         * debugging since the CPU will be prevented from accessing
         * RAR memory by the hardware when RAR is properly locked
         * down.
         *
         * In order for this implementation to be useful RAR memory
         * must be not be locked down.  However, we only want to do
         * that when debugging.  DO NOT leave RAR memory unlocked in a
         * deployed device that utilizes RAR.
         */

        size_t const size = vma->vm_end - vma->vm_start;

        /* Users pass the RAR handle as the mmap() offset parameter. */
        unsigned long const handle = vma->vm_pgoff << PAGE_SHIFT;

        struct memrar_rar_info * const rar = memrar_get_rar_info(handle);
        unsigned long pfn;

        /* Only allow priviledged apps to go poking around this way */
        if (!capable(CAP_SYS_RAWIO))
                return -EPERM;

        /* Invalid RAR handle or size passed to mmap(). */
        if (rar == NULL
            || handle == 0
            || size > (handle - (unsigned long) rar->iobase))
                return -EINVAL;

        /*
         * Retrieve physical address corresponding to the RAR handle,
         * and convert it to a page frame.
         */
        pfn = memrar_get_physical_address(rar, handle) >> PAGE_SHIFT;


        pr_debug("memrar: mapping RAR range [0x%lx, 0x%lx) into user space.\n",
                 handle,
                 handle + size);

        /*
         * Map RAR memory into user space.  This is really only useful
         * for debugging purposes since the memory won't be
         * accessible, i.e. reads return zero and writes are ignored,
         * when RAR access control is enabled.
         */
        if (remap_pfn_range(vma,
                            vma->vm_start,
                            pfn,
                            size,
                            vma->vm_page_prot))
                return -EAGAIN;

        /* vma->vm_ops = &memrar_mem_ops; */

        return 0;
}

/**
 *      memrar_open             -       device open method
 *      @inode: inode to open
 *      @filp: file handle
 *
 *      As we support multiple arbitary opens there is no work to be done
 *      really.
 */

static int memrar_open(struct inode *inode, struct file *filp)
{
        nonseekable_open(inode, filp);
        return 0;
}

/**
 *      memrar_release          -       close method for miscev
 *      @inode: inode of device
 *      @filp: handle that is going away
 *
 *      Free up all the regions that belong to this file handle. We use
 *      the handle as a natural Linux style 'lifetime' indicator and to
 *      ensure resources are not leaked when their owner explodes in an
 *      unplanned fashion.
 */

static int memrar_release(struct inode *inode, struct file *filp)
{
        /* Free all regions associated with the given file handle. */

        struct memrar_buffer_info *pos;
        struct memrar_buffer_info *tmp;
        int z;

        for (z = 0; z != MRST_NUM_RAR; ++z) {
                struct memrar_rar_info * const rar = &memrars[z];

                mutex_lock(&rar->lock);

                list_for_each_entry_safe(pos,
                                         tmp,
                                         &rar->buffers.list,
                                         list) {
                        if (filp == pos->owner)
                                kref_put(&pos->refcount,
                                         memrar_release_block_i);
                }

                mutex_unlock(&rar->lock);
        }

        return 0;
}

/**
 *      rar_reserve             -       reserve RAR memory
 *      @buffers: buffers to reserve
 *      @count: number wanted
 *
 *      Reserve a series of buffers in the RAR space. Returns the number of
 *      buffers successfully allocated
 */

size_t rar_reserve(struct RAR_buffer *buffers, size_t count)
{
        struct RAR_buffer * const end =
                (buffers == NULL ? buffers : buffers + count);
        struct RAR_buffer *i;

        size_t reserve_count = 0;

        for (i = buffers; i != end; ++i) {
                if (memrar_reserve_block(i, NULL) == 0)
                        ++reserve_count;
                else
                        i->bus_address = 0;
        }

        return reserve_count;
}
EXPORT_SYMBOL(rar_reserve);

/**
 *      rar_release             -       return RAR buffers
 *      @buffers: buffers to release
 *      @size: size of released block
 *
 *      Return a set of buffers to the RAR pool
 */

size_t rar_release(struct RAR_buffer *buffers, size_t count)
{
        struct RAR_buffer * const end =
                (buffers == NULL ? buffers : buffers + count);
        struct RAR_buffer *i;

        size_t release_count = 0;

        for (i = buffers; i != end; ++i) {
                u32 * const handle = &i->info.handle;
                if (memrar_release_block(*handle) == 0) {
                        /*
                         * @todo We assume we should do this each time
                         *       the ref count is decremented.  Should
                         *       we instead only do this when the ref
                         *       count has dropped to zero, and the
                         *       buffer has been completely
                         *       released/unmapped?
                         */
                        *handle = 0;
                        ++release_count;
                }
        }

        return release_count;
}
EXPORT_SYMBOL(rar_release);

/**
 *      rar_handle_to_bus       -       RAR to bus address
 *      @buffers: RAR buffer structure
 *      @count: number of buffers to convert
 *
 *      Turn a list of RAR handle mappings into actual bus addresses. Note
 *      that when the device is locked down the bus addresses in question
 *      are not CPU accessible.
 */

size_t rar_handle_to_bus(struct RAR_buffer *buffers, size_t count)
{
        struct RAR_buffer * const end =
                (buffers == NULL ? buffers : buffers + count);
        struct RAR_buffer *i;
        struct memrar_buffer_info *pos;

        size_t conversion_count = 0;

        /*
         * Find all bus addresses corresponding to the given handles.
         *
         * @todo Not liking this nested loop.  Optimize.
         */
        for (i = buffers; i != end; ++i) {
                struct memrar_rar_info * const rar =
                        memrar_get_rar_info(i->info.handle);

                /*
                 * Check if we have a bogus handle, and then continue
                 * with remaining buffers.
                 */
                if (rar == NULL) {
                        i->bus_address = 0;
                        continue;
                }

                mutex_lock(&rar->lock);

                list_for_each_entry(pos, &rar->buffers.list, list) {
                        struct RAR_block_info * const user_info =
                                &pos->buffer.info;

                        /*
                         * Take into account handle offsets that may
                         * have been added to the base handle, such as
                         * in the following scenario:
                         *
                         *     u32 handle = base + offset;
                         *     rar_handle_to_bus(handle);
                         */

                        if (i->info.handle >= user_info->handle
                            && i->info.handle < (user_info->handle
                                                 + user_info->size)) {
                                u32 const offset =
                                        i->info.handle - user_info->handle;

                                i->info.type = user_info->type;
                                i->info.size = user_info->size - offset;
                                i->bus_address =
                                        pos->buffer.bus_address
                                        + offset;

                                /* Increment the reference count. */
                                kref_get(&pos->refcount);

                                ++conversion_count;
                                break;
                        } else {
                                i->bus_address = 0;
                        }
                }

                mutex_unlock(&rar->lock);
        }

        return conversion_count;
}
EXPORT_SYMBOL(rar_handle_to_bus);

static const struct file_operations memrar_fops = {
        .owner = THIS_MODULE,
        .unlocked_ioctl = memrar_ioctl,
        .mmap           = memrar_mmap,
        .open           = memrar_open,
        .release        = memrar_release,
        .llseek         = no_llseek,
};

static struct miscdevice memrar_miscdev = {
        .minor = MISC_DYNAMIC_MINOR,    /* dynamic allocation */
        .name = "memrar",               /* /dev/memrar */
        .fops = &memrar_fops
};

static char const banner[] __initdata =
        KERN_INFO
        "Intel RAR Handler: " MEMRAR_VER " initialized.\n";

/**
 *      memrar_registration_callback    -       RAR obtained
 *      @rar: RAR number
 *
 *      We have been granted ownership of the RAR. Add it to our memory
 *      management tables
 */

static int memrar_registration_callback(unsigned long rar)
{
        /*
         * We initialize the RAR parameters early on so that we can
         * discontinue memrar device initialization and registration
         * if suitably configured RARs are not available.
         */
        return memrar_init_rar_resources(rar, memrar_miscdev.name);
}

/**
 *      memrar_init     -       initialise RAR support
 *
 *      Initialise support for RAR handlers. This may get loaded before
 *      the RAR support is activated, but the callbacks on the registration
 *      will handle that situation for us anyway.
 */

static int __init memrar_init(void)
{
        int err;
        int i;

        printk(banner);

        /*
         * Some delayed initialization is performed in this driver.
         * Make sure resources that are used during driver clean-up
         * (e.g. during driver's release() function) are fully
         * initialized before first use.  This is particularly
         * important for the case when the delayed initialization
         * isn't completed, leaving behind a partially initialized
         * driver.
         *
         * Such a scenario can occur when RAR is not available on the
         * platform, and the driver is release()d.
         */
        for (i = 0; i != ARRAY_SIZE(memrars); ++i) {
                struct memrar_rar_info * const rar = &memrars[i];
                mutex_init(&rar->lock);
                INIT_LIST_HEAD(&rar->buffers.list);
        }

        err = misc_register(&memrar_miscdev);
        if (err)
                return err;

        /* Now claim the two RARs we want */
        err = register_rar(0, memrar_registration_callback, 0);
        if (err)
                goto fail;

        err = register_rar(1, memrar_registration_callback, 1);
        if (err == 0)
                return 0;

        /* It is possible rar 0 registered and allocated resources then rar 1
           failed so do a full resource free */
        memrar_fini_rar_resources();
fail:
        misc_deregister(&memrar_miscdev);
        return err;
}

/**
 *      memrar_exit     -       unregister and unload
 *
 *      Unregister the device and then unload any mappings and release
 *      the RAR resources
 */

static void __exit memrar_exit(void)
{
        misc_deregister(&memrar_miscdev);
        memrar_fini_rar_resources();
}


module_init(memrar_init);
module_exit(memrar_exit);


MODULE_AUTHOR("Ossama Othman <ossama.othman@intel.com>");
MODULE_DESCRIPTION("Intel Restricted Access Region Handler");
MODULE_LICENSE("GPL");
MODULE_VERSION(MEMRAR_VER);

/*
  Local Variables:
    c-file-style: "linux"
  End:
*/