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); 185