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