--- /dev/null
+/**************************************************************************
+ *
+ * Copyright 2010 Pauli Nieminen.
+ * All Rights Reserved.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the
+ * "Software"), to deal in the Software without restriction, including
+ * without limitation the rights to use, copy, modify, merge, publish,
+ * distribute, sub license, and/or sell copies of the Software, and to
+ * permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the
+ * next paragraph) shall be included in all copies or substantial portions
+ * of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL
+ * THE COPYRIGHT HOLDERS, AUTHORS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM,
+ * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
+ * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
+ * USE OR OTHER DEALINGS IN THE SOFTWARE.
+ *
+ *
+ **************************************************************************/
+/*
+ * Multipart buffer for coping data which is larger than the page size.
+ *
+ * Authors:
+ * Pauli Nieminen <suokkos-at-gmail-dot-com>
+ */
+
+#include <linux/export.h>
+#include "drm_buffer.h"
+
+/**
+ * Allocate the drm buffer object.
+ *
+ * buf: Pointer to a pointer where the object is stored.
+ * size: The number of bytes to allocate.
+ */
+int drm_buffer_alloc(struct drm_buffer **buf, int size)
+{
+ int nr_pages = size / PAGE_SIZE + 1;
+ int idx;
+
+ /* Allocating pointer table to end of structure makes drm_buffer
+ * variable sized */
+ *buf = kzalloc(sizeof(struct drm_buffer) + nr_pages*sizeof(char *),
+ GFP_KERNEL);
+
+ if (*buf == NULL) {
+ DRM_ERROR("Failed to allocate drm buffer object to hold"
+ " %d bytes in %d pages.\n",
+ size, nr_pages);
+ return -ENOMEM;
+ }
+
+ (*buf)->size = size;
+
+ for (idx = 0; idx < nr_pages; ++idx) {
+
+ (*buf)->data[idx] =
+ kmalloc(min(PAGE_SIZE, size - idx * PAGE_SIZE),
+ GFP_KERNEL);
+
+
+ if ((*buf)->data[idx] == NULL) {
+ DRM_ERROR("Failed to allocate %dth page for drm"
+ " buffer with %d bytes and %d pages.\n",
+ idx + 1, size, nr_pages);
+ goto error_out;
+ }
+
+ }
+
+ return 0;
+
+error_out:
+
+ for (; idx >= 0; --idx)
+ kfree((*buf)->data[idx]);
+
+ kfree(*buf);
+ return -ENOMEM;
+}
+
+/**
+ * Copy the user data to the begin of the buffer and reset the processing
+ * iterator.
+ *
+ * user_data: A pointer the data that is copied to the buffer.
+ * size: The Number of bytes to copy.
+ */
+int drm_buffer_copy_from_user(struct drm_buffer *buf,
+ void __user *user_data, int size)
+{
+ int nr_pages = size / PAGE_SIZE + 1;
+ int idx;
+
+ if (size > buf->size) {
+ DRM_ERROR("Requesting to copy %d bytes to a drm buffer with"
+ " %d bytes space\n",
+ size, buf->size);
+ return -EFAULT;
+ }
+
+ for (idx = 0; idx < nr_pages; ++idx) {
+
+ if (copy_from_user(buf->data[idx],
+ user_data + idx * PAGE_SIZE,
+ min(PAGE_SIZE, size - idx * PAGE_SIZE))) {
+ DRM_ERROR("Failed to copy user data (%p) to drm buffer"
+ " (%p) %dth page.\n",
+ user_data, buf, idx);
+ return -EFAULT;
+
+ }
+ }
+ buf->iterator = 0;
+ return 0;
+}
+
+/**
+ * Free the drm buffer object
+ */
+void drm_buffer_free(struct drm_buffer *buf)
+{
+
+ if (buf != NULL) {
+
+ int nr_pages = buf->size / PAGE_SIZE + 1;
+ int idx;
+ for (idx = 0; idx < nr_pages; ++idx)
+ kfree(buf->data[idx]);
+
+ kfree(buf);
+ }
+}
+
+/**
+ * Read an object from buffer that may be split to multiple parts. If object
+ * is not split function just returns the pointer to object in buffer. But in
+ * case of split object data is copied to given stack object that is suplied
+ * by caller.
+ *
+ * The processing location of the buffer is also advanced to the next byte
+ * after the object.
+ *
+ * objsize: The size of the objet in bytes.
+ * stack_obj: A pointer to a memory location where object can be copied.
+ */
+void *drm_buffer_read_object(struct drm_buffer *buf,
+ int objsize, void *stack_obj)
+{
+ int idx = drm_buffer_index(buf);
+ int page = drm_buffer_page(buf);
+ void *obj = NULL;
+
+ if (idx + objsize <= PAGE_SIZE) {
+ obj = &buf->data[page][idx];
+ } else {
+ /* The object is split which forces copy to temporary object.*/
+ int beginsz = PAGE_SIZE - idx;
+ memcpy(stack_obj, &buf->data[page][idx], beginsz);
+
+ memcpy(stack_obj + beginsz, &buf->data[page + 1][0],
+ objsize - beginsz);
+
+ obj = stack_obj;
+ }
+
+ drm_buffer_advance(buf, objsize);
+ return obj;
+}
Code Review / kvmfornfv.git / blobdiff