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 <sys/cdefs.h> 36 #ifndef _DRM_BUFFER_H_ 37 #define _DRM_BUFFER_H_ 38 39 #include <dev/drm2/drmP.h> 40 41 struct drm_buffer { 42 int iterator; 43 int size; 44 char *data[]; 45 }; 46 47 48 /** 49 * Return the index of page that buffer is currently pointing at. 50 */ 51 static inline int drm_buffer_page(struct drm_buffer *buf) 52 { 53 return buf->iterator / PAGE_SIZE; 54 } 55 /** 56 * Return the index of the current byte in the page 57 */ 58 static inline int drm_buffer_index(struct drm_buffer *buf) 59 { 60 return buf->iterator & (PAGE_SIZE - 1); 61 } 62 /** 63 * Return number of bytes that is left to process 64 */ 65 static inline int drm_buffer_unprocessed(struct drm_buffer *buf) 66 { 67 return buf->size - buf->iterator; 68 } 69 70 /** 71 * Advance the buffer iterator number of bytes that is given. 72 */ 73 static inline void drm_buffer_advance(struct drm_buffer *buf, int bytes) 74 { 75 buf->iterator += bytes; 76 } 77 78 /** 79 * Allocate the drm buffer object. 80 * 81 * buf: A pointer to a pointer where the object is stored. 82 * size: The number of bytes to allocate. 83 */ 84 extern int drm_buffer_alloc(struct drm_buffer **buf, int size); 85 86 /** 87 * Copy the user data to the begin of the buffer and reset the processing 88 * iterator. 89 * 90 * user_data: A pointer the data that is copied to the buffer. 91 * size: The Number of bytes to copy. 92 */ 93 extern int drm_buffer_copy_from_user(struct drm_buffer *buf, 94 void __user *user_data, int size); 95 96 /** 97 * Free the drm buffer object 98 */ 99 extern void drm_buffer_free(struct drm_buffer *buf); 100 101 /** 102 * Read an object from buffer that may be split to multiple parts. If object 103 * is not split function just returns the pointer to object in buffer. But in 104 * case of split object data is copied to given stack object that is suplied 105 * by caller. 106 * 107 * The processing location of the buffer is also advanced to the next byte 108 * after the object. 109 * 110 * objsize: The size of the objet in bytes. 111 * stack_obj: A pointer to a memory location where object can be copied. 112 */ 113 extern void *drm_buffer_read_object(struct drm_buffer *buf, 114 int objsize, void *stack_obj); 115 116 /** 117 * Returns the pointer to the dword which is offset number of elements from the 118 * current processing location. 119 * 120 * Caller must make sure that dword is not split in the buffer. This 121 * requirement is easily met if all the sizes of objects in buffer are 122 * multiples of dword and PAGE_SIZE is multiple dword. 123 * 124 * Call to this function doesn't change the processing location. 125 * 126 * offset: The index of the dword relative to the internat iterator. 127 */ 128 static inline void *drm_buffer_pointer_to_dword(struct drm_buffer *buffer, 129 int offset) 130 { 131 int iter = buffer->iterator + offset * 4; 132 return &buffer->data[iter / PAGE_SIZE][iter & (PAGE_SIZE - 1)]; 133 } 134 /** 135 * Returns the pointer to the dword which is offset number of elements from 136 * the current processing location. 137 * 138 * Call to this function doesn't change the processing location. 139 * 140 * offset: The index of the byte relative to the internat iterator. 141 */ 142 static inline void *drm_buffer_pointer_to_byte(struct drm_buffer *buffer, 143 int offset) 144 { 145 int iter = buffer->iterator + offset; 146 return &buffer->data[iter / PAGE_SIZE][iter & (PAGE_SIZE - 1)]; 147 } 148 149 #endif 150