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authorOssama Othman <ossama.othman@intel.com>2010-03-15 16:23:56 -0700
committerGreg Kroah-Hartman <gregkh@suse.de>2010-05-11 11:35:33 -0700
commitff13209b00dd4f67f676dd8567a9e95f13f4388c (patch)
tree381ae33e482157b3bfe68c50c67bf12c5c78932f /drivers/staging/memrar/memrar_handler.c
parent3504e0c87892c272d9784e12918910d74077da0d (diff)
staging: Intel Restricted Access Region Handler
The Intel Restricted Access Region Handler provides a buffer allocation mechanism to RAR users. Since the intended usage model is to lock out CPU access to RAR (the CPU will not be able to access RAR memory), this driver does not access RAR memory, and merely keeps track of what areas of RAR memory are in use. It has it's own simple allocator that does not rely on existing kernel allocators (SLAB, etc) since those allocators are too tightly coupled with the paging mechanism, which isn't needed for the intended RAR use cases. An mmap() implementation is provided for debugging purposes to simplify RAR memory access from the user space. However, it will effectively be a no-op when RAR access control is enabled since the CPU will not be able to access RAR. This driver should not be confused with the rar_register driver. That driver exposes an interface to access RAR registers on the Moorestown platform. The RAR handler driver relies on the rar_register driver for low level RAR register reads and writes. This patch was generated and built against the latest linux-2.6 master branch. Signed-off-by: Ossama Othman <ossama.othman@intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'drivers/staging/memrar/memrar_handler.c')
-rw-r--r--drivers/staging/memrar/memrar_handler.c937
1 files changed, 937 insertions, 0 deletions
diff --git a/drivers/staging/memrar/memrar_handler.c b/drivers/staging/memrar/memrar_handler.c
new file mode 100644
index 00000000000..4bbf66f4223
--- /dev/null
+++ b/drivers/staging/memrar/memrar_handler.c
@@ -0,0 +1,937 @@
+/*
+ * 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 "../rar_register/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;
+};
+
+/*
+ * 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;
+}
+
+/*
+ * 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);
+}
+
+/*
+ * 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);
+}
+
+/*
+ * Core block release code.
+ *
+ * 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);
+}
+
+/*
+ * Initialize RAR parameters, such as bus addresses, etc.
+ */
+static int memrar_init_rar_resources(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;
+
+ int z;
+ int found_rar = 0;
+
+ BUG_ON(MRST_NUM_RAR != ARRAY_SIZE(memrars));
+
+ for (z = 0; z != MRST_NUM_RAR; ++z) {
+ dma_addr_t low, high;
+ struct memrar_rar_info * const rar = &memrars[z];
+
+ BUG_ON(!memrar_is_valid_rar_type(z));
+
+ mutex_init(&rar->lock);
+
+ /*
+ * Initialize the process table before we reach any
+ * code that exit on failure since the finalization
+ * code requires an initialized list.
+ */
+ INIT_LIST_HEAD(&rar->buffers.list);
+
+ if (rar_get_address(z, &low, &high) != 0) {
+ /* No RAR is available. */
+ break;
+ } else if (low == 0 || high == 0) {
+ /*
+ * We don't immediately break out of the loop
+ * since the next type of RAR may be enabled.
+ */
+ rar->base = 0;
+ rar->length = 0;
+ rar->iobase = NULL;
+ rar->allocator = NULL;
+ continue;
+ }
+
+ /*
+ * @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,
+ z);
+ pr_err("%s: RAR[%d] disabled.\n", devname, z);
+
+ /*
+ * Rather than break out of the loop by
+ * returning -EBUSY, for example, we may be
+ * able to claim memory of the next RAR region
+ * as our own.
+ */
+ continue;
+ }
+
+ 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);
+ return -ENOMEM;
+ }
+
+ /* Initialize corresponding memory allocator. */
+ rar->allocator = memrar_create_allocator(
+ (unsigned long) rar->iobase,
+ rar->length,
+ RAR_BLOCK_SIZE);
+ if (rar->allocator == NULL)
+ return -1;
+
+ /*
+ * -------------------------------------------------
+ * Make sure all RARs handled by us are locked down.
+ * -------------------------------------------------
+ */
+
+ /* Enable RAR protection on the Lincroft side. */
+ if (0) {
+ /*
+ * This is mostly a sanity check since the
+ * vendor should have locked down RAR in the
+ * SMIP header RAR configuration.
+ */
+ rar_lock(z);
+ } else {
+ pr_warning("%s: LNC RAR[%d] no lock sanity check.\n",
+ devname,
+ z);
+ }
+
+ /* ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ */
+ /* |||||||||||||||||||||||||||||||||||||||||||||||||| */
+
+ /*
+ * It would be nice if we could verify that RAR
+ * protection on the Langwell side is enabled, but
+ * there is no way to do that from here. The
+ * necessary Langwell RAR registers are not accessible
+ * from the Lincroft (IA) side.
+ *
+ * Hopefully the ODM did the right thing and enabled
+ * Langwell side RAR protection in the integrated
+ * firmware SMIP header.
+ */
+
+ pr_info("%s: BRAR[%d] bus address range = "
+ "[0x%lx, 0x%lx]\n",
+ devname,
+ z,
+ (unsigned long) low,
+ (unsigned long) high);
+
+ pr_info("%s: BRAR[%d] size = %u KiB\n",
+ devname,
+ z,
+ rar->allocator->capacity / 1024);
+
+ found_rar = 1;
+ }
+
+ if (!found_rar) {
+ /*
+ * No RAR support. Don't bother continuing.
+ *
+ * Note that this is not a failure.
+ */
+ pr_info("%s: No Moorestown RAR support available.\n",
+ devname);
+ return -ENODEV;
+ }
+
+ return 0;
+}
+
+/*
+ * Finalize RAR resources.
+ */
+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];
+
+ /* 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);
+ rar->iobase = NULL;
+
+ release_mem_region(rar->base, rar->length);
+ rar->base = 0;
+
+ rar->length = 0;
+ }
+}
+
+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];
+
+ /* 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;
+}
+
+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 -EFAULT;
+
+ 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;
+}
+
+static long memrar_get_stat(struct RAR_stat *r)
+{
+ long result = -EINVAL;
+
+ if (likely(r != NULL) && memrar_is_valid_rar_type(r->type)) {
+ struct memrar_allocator * const 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);
+
+ result = 0;
+ }
+
+ return result;
+}
+
+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;
+}
+
+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;
+
+ /* 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;
+}
+
+static int memrar_open(struct inode *inode, struct file *filp)
+{
+ /* Nothing to do yet. */
+
+ return 0;
+}
+
+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;
+}
+
+/*
+ * This function is part of the kernel space memrar driver API.
+ */
+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);
+
+/*
+ * This function is part of the kernel space memrar driver API.
+ */
+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);
+
+/*
+ * This function is part of the kernel space driver API.
+ */
+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,
+};
+
+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";
+
+static int memrar_registration_callback(void *ctx)
+{
+ /*
+ * We initialize the RAR parameters early on so that we can
+ * discontinue memrar device initialization and registration
+ * if suitably configured RARs are not available.
+ */
+ int result = memrar_init_rar_resources(memrar_miscdev.name);
+
+ if (result != 0)
+ return result;
+
+ result = misc_register(&memrar_miscdev);
+
+ if (result != 0) {
+ pr_err("%s: misc_register() failed.\n",
+ memrar_miscdev.name);
+
+ /* Clean up resources previously reserved. */
+ memrar_fini_rar_resources();
+ }
+
+ return result;
+}
+
+static int __init memrar_init(void)
+{
+ printk(banner);
+
+ return register_rar(&memrar_registration_callback, 0);
+}
+
+static void __exit memrar_exit(void)
+{
+ memrar_fini_rar_resources();
+
+ misc_deregister(&memrar_miscdev);
+}
+
+
+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_ALIAS_MISCDEV(MISC_DYNAMIC_MINOR);
+MODULE_VERSION(MEMRAR_VER);
+
+
+
+/*
+ Local Variables:
+ c-file-style: "linux"
+ End:
+*/