1/**************************************************************************
  2 *
  3 * Copyright 2010 Pauli Nieminen.
  4 * All Rights Reserved.
  5 *
  6 * Permission is hereby granted, free of charge, to any person obtaining a
  7 * copy of this software and associated documentation files (the
  8 * "Software"), to deal in the Software without restriction, including
  9 * without limitation the rights to use, copy, modify, merge, publish,
 10 * distribute, sub license, and/or sell copies of the Software, and to
 11 * permit persons to whom the Software is furnished to do so, subject to
 12 * the following conditions:
 13 *
 14 * The above copyright notice and this permission notice (including the
 15 * next paragraph) shall be included in all copies or substantial portions
 16 * of the Software.
 17 *
 18 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 19 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 20 * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL
 21 * THE COPYRIGHT HOLDERS, AUTHORS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM,
 22 * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
 23 * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
 24 * USE OR OTHER DEALINGS IN THE SOFTWARE.
 25 *
 26 *
 27 **************************************************************************/
 28/*
 29 * Multipart buffer for coping data which is larger than the page size.
 30 *
 31 * Authors:
 32 * Pauli Nieminen <suokkos-at-gmail-dot-com>
 33 */
 34
 35#include "drm_buffer.h"
 36
 37/**
 38 * Allocate the drm buffer object.
 39 *
 40 *   buf: Pointer to a pointer where the object is stored.
 41 *   size: The number of bytes to allocate.
 42 */
 43int drm_buffer_alloc(struct drm_buffer **buf, int size)
 44{
 45	int nr_pages = size / PAGE_SIZE + 1;
 46	int idx;
 47
 48	/* Allocating pointer table to end of structure makes drm_buffer
 49	 * variable sized */
 50	*buf = kzalloc(sizeof(struct drm_buffer) + nr_pages*sizeof(char *),
 51			GFP_KERNEL);
 52
 53	if (*buf == NULL) {
 54		DRM_ERROR("Failed to allocate drm buffer object to hold"
 55				" %d bytes in %d pages.\n",
 56				size, nr_pages);
 57		return -ENOMEM;
 58	}
 59
 60	(*buf)->size = size;
 61
 62	for (idx = 0; idx < nr_pages; ++idx) {
 63
 64		(*buf)->data[idx] =
 65			kmalloc(min(PAGE_SIZE, size - idx * PAGE_SIZE),
 66				GFP_KERNEL);
 67
 68
 69		if ((*buf)->data[idx] == NULL) {
 70			DRM_ERROR("Failed to allocate %dth page for drm"
 71					" buffer with %d bytes and %d pages.\n",
 72					idx + 1, size, nr_pages);
 73			goto error_out;
 74		}
 75
 76	}
 77
 78	return 0;
 79
 80error_out:
 81
 82	/* Only last element can be null pointer so check for it first. */
 83	if ((*buf)->data[idx])
 84		kfree((*buf)->data[idx]);
 85
 86	for (--idx; idx >= 0; --idx)
 87		kfree((*buf)->data[idx]);
 88
 89	kfree(*buf);
 90	return -ENOMEM;
 91}
 92EXPORT_SYMBOL(drm_buffer_alloc);
 93
 94/**
 95 * Copy the user data to the begin of the buffer and reset the processing
 96 * iterator.
 97 *
 98 *   user_data: A pointer the data that is copied to the buffer.
 99 *   size: The Number of bytes to copy.
100 */
101int drm_buffer_copy_from_user(struct drm_buffer *buf,
102			      void __user *user_data, int size)
103{
104	int nr_pages = size / PAGE_SIZE + 1;
105	int idx;
106
107	if (size > buf->size) {
108		DRM_ERROR("Requesting to copy %d bytes to a drm buffer with"
109				" %d bytes space\n",
110				size, buf->size);
111		return -EFAULT;
112	}
113
114	for (idx = 0; idx < nr_pages; ++idx) {
115
116		if (DRM_COPY_FROM_USER(buf->data[idx],
117			user_data + idx * PAGE_SIZE,
118			min(PAGE_SIZE, size - idx * PAGE_SIZE))) {
119			DRM_ERROR("Failed to copy user data (%p) to drm buffer"
120					" (%p) %dth page.\n",
121					user_data, buf, idx);
122			return -EFAULT;
123
124		}
125	}
126	buf->iterator = 0;
127	return 0;
128}
129EXPORT_SYMBOL(drm_buffer_copy_from_user);
130
131/**
132 * Free the drm buffer object
133 */
134void drm_buffer_free(struct drm_buffer *buf)
135{
136
137	if (buf != NULL) {
138
139		int nr_pages = buf->size / PAGE_SIZE + 1;
140		int idx;
141		for (idx = 0; idx < nr_pages; ++idx)
142			kfree(buf->data[idx]);
143
144		kfree(buf);
145	}
146}
147EXPORT_SYMBOL(drm_buffer_free);
148
149/**
150 * Read an object from buffer that may be split to multiple parts. If object
151 * is not split function just returns the pointer to object in buffer. But in
152 * case of split object data is copied to given stack object that is suplied
153 * by caller.
154 *
155 * The processing location of the buffer is also advanced to the next byte
156 * after the object.
157 *
158 *   objsize: The size of the objet in bytes.
159 *   stack_obj: A pointer to a memory location where object can be copied.
160 */
161void *drm_buffer_read_object(struct drm_buffer *buf,
162		int objsize, void *stack_obj)
163{
164	int idx = drm_buffer_index(buf);
165	int page = drm_buffer_page(buf);
166	void *obj = NULL;
167
168	if (idx + objsize <= PAGE_SIZE) {
169		obj = &buf->data[page][idx];
170	} else {
171		/* The object is split which forces copy to temporary object.*/
172		int beginsz = PAGE_SIZE - idx;
173		memcpy(stack_obj, &buf->data[page][idx], beginsz);
174
175		memcpy(stack_obj + beginsz, &buf->data[page + 1][0],
176				objsize - beginsz);
177
178		obj = stack_obj;
179	}
180
181	drm_buffer_advance(buf, objsize);
182	return obj;
183}
184EXPORT_SYMBOL(drm_buffer_read_object);