/**************************************************************************
*
* 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;
}
