length.h 4.9 KB

123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154155156157158159160161162163164165166167168169170171172173174175176
  1. /* SPDX-License-Identifier: GPL-2.0 */
  2. /* Copyright (C) 2020 Oliver Hartkopp <[email protected]>
  3. * Copyright (C) 2020 Marc Kleine-Budde <[email protected]>
  4. */
  5. #ifndef _CAN_LENGTH_H
  6. #define _CAN_LENGTH_H
  7. /*
  8. * Size of a Classical CAN Standard Frame
  9. *
  10. * Name of Field Bits
  11. * ---------------------------------------------------------
  12. * Start-of-frame 1
  13. * Identifier 11
  14. * Remote transmission request (RTR) 1
  15. * Identifier extension bit (IDE) 1
  16. * Reserved bit (r0) 1
  17. * Data length code (DLC) 4
  18. * Data field 0...64
  19. * CRC 15
  20. * CRC delimiter 1
  21. * ACK slot 1
  22. * ACK delimiter 1
  23. * End-of-frame (EOF) 7
  24. * Inter frame spacing 3
  25. *
  26. * rounded up and ignoring bitstuffing
  27. */
  28. #define CAN_FRAME_OVERHEAD_SFF DIV_ROUND_UP(47, 8)
  29. /*
  30. * Size of a Classical CAN Extended Frame
  31. *
  32. * Name of Field Bits
  33. * ---------------------------------------------------------
  34. * Start-of-frame 1
  35. * Identifier A 11
  36. * Substitute remote request (SRR) 1
  37. * Identifier extension bit (IDE) 1
  38. * Identifier B 18
  39. * Remote transmission request (RTR) 1
  40. * Reserved bits (r1, r0) 2
  41. * Data length code (DLC) 4
  42. * Data field 0...64
  43. * CRC 15
  44. * CRC delimiter 1
  45. * ACK slot 1
  46. * ACK delimiter 1
  47. * End-of-frame (EOF) 7
  48. * Inter frame spacing 3
  49. *
  50. * rounded up and ignoring bitstuffing
  51. */
  52. #define CAN_FRAME_OVERHEAD_EFF DIV_ROUND_UP(67, 8)
  53. /*
  54. * Size of a CAN-FD Standard Frame
  55. *
  56. * Name of Field Bits
  57. * ---------------------------------------------------------
  58. * Start-of-frame 1
  59. * Identifier 11
  60. * Reserved bit (r1) 1
  61. * Identifier extension bit (IDE) 1
  62. * Flexible data rate format (FDF) 1
  63. * Reserved bit (r0) 1
  64. * Bit Rate Switch (BRS) 1
  65. * Error Status Indicator (ESI) 1
  66. * Data length code (DLC) 4
  67. * Data field 0...512
  68. * Stuff Bit Count (SBC) 4
  69. * CRC 0...16: 17 20...64:21
  70. * CRC delimiter (CD) 1
  71. * Fixed Stuff bits (FSB) 0...16: 6 20...64:7
  72. * ACK slot (AS) 1
  73. * ACK delimiter (AD) 1
  74. * End-of-frame (EOF) 7
  75. * Inter frame spacing 3
  76. *
  77. * assuming CRC21, rounded up and ignoring dynamic bitstuffing
  78. */
  79. #define CANFD_FRAME_OVERHEAD_SFF DIV_ROUND_UP(67, 8)
  80. /*
  81. * Size of a CAN-FD Extended Frame
  82. *
  83. * Name of Field Bits
  84. * ---------------------------------------------------------
  85. * Start-of-frame 1
  86. * Identifier A 11
  87. * Substitute remote request (SRR) 1
  88. * Identifier extension bit (IDE) 1
  89. * Identifier B 18
  90. * Reserved bit (r1) 1
  91. * Flexible data rate format (FDF) 1
  92. * Reserved bit (r0) 1
  93. * Bit Rate Switch (BRS) 1
  94. * Error Status Indicator (ESI) 1
  95. * Data length code (DLC) 4
  96. * Data field 0...512
  97. * Stuff Bit Count (SBC) 4
  98. * CRC 0...16: 17 20...64:21
  99. * CRC delimiter (CD) 1
  100. * Fixed Stuff bits (FSB) 0...16: 6 20...64:7
  101. * ACK slot (AS) 1
  102. * ACK delimiter (AD) 1
  103. * End-of-frame (EOF) 7
  104. * Inter frame spacing 3
  105. *
  106. * assuming CRC21, rounded up and ignoring dynamic bitstuffing
  107. */
  108. #define CANFD_FRAME_OVERHEAD_EFF DIV_ROUND_UP(86, 8)
  109. /*
  110. * Maximum size of a Classical CAN frame
  111. * (rounded up and ignoring bitstuffing)
  112. */
  113. #define CAN_FRAME_LEN_MAX (CAN_FRAME_OVERHEAD_EFF + CAN_MAX_DLEN)
  114. /*
  115. * Maximum size of a CAN-FD frame
  116. * (rounded up and ignoring bitstuffing)
  117. */
  118. #define CANFD_FRAME_LEN_MAX (CANFD_FRAME_OVERHEAD_EFF + CANFD_MAX_DLEN)
  119. /*
  120. * can_cc_dlc2len(value) - convert a given data length code (dlc) of a
  121. * Classical CAN frame into a valid data length of max. 8 bytes.
  122. *
  123. * To be used in the CAN netdriver receive path to ensure conformance with
  124. * ISO 11898-1 Chapter 8.4.2.3 (DLC field)
  125. */
  126. #define can_cc_dlc2len(dlc) (min_t(u8, (dlc), CAN_MAX_DLEN))
  127. /* helper to get the data length code (DLC) for Classical CAN raw DLC access */
  128. static inline u8 can_get_cc_dlc(const struct can_frame *cf, const u32 ctrlmode)
  129. {
  130. /* return len8_dlc as dlc value only if all conditions apply */
  131. if ((ctrlmode & CAN_CTRLMODE_CC_LEN8_DLC) &&
  132. (cf->len == CAN_MAX_DLEN) &&
  133. (cf->len8_dlc > CAN_MAX_DLEN && cf->len8_dlc <= CAN_MAX_RAW_DLC))
  134. return cf->len8_dlc;
  135. /* return the payload length as dlc value */
  136. return cf->len;
  137. }
  138. /* helper to set len and len8_dlc value for Classical CAN raw DLC access */
  139. static inline void can_frame_set_cc_len(struct can_frame *cf, const u8 dlc,
  140. const u32 ctrlmode)
  141. {
  142. /* the caller already ensured that dlc is a value from 0 .. 15 */
  143. if (ctrlmode & CAN_CTRLMODE_CC_LEN8_DLC && dlc > CAN_MAX_DLEN)
  144. cf->len8_dlc = dlc;
  145. /* limit the payload length 'len' to CAN_MAX_DLEN */
  146. cf->len = can_cc_dlc2len(dlc);
  147. }
  148. /* get data length from raw data length code (DLC) */
  149. u8 can_fd_dlc2len(u8 dlc);
  150. /* map the sanitized data length to an appropriate data length code */
  151. u8 can_fd_len2dlc(u8 len);
  152. /* calculate the CAN Frame length in bytes of a given skb */
  153. unsigned int can_skb_get_frame_len(const struct sk_buff *skb);
  154. /* map the data length to an appropriate data link layer length */
  155. static inline u8 canfd_sanitize_len(u8 len)
  156. {
  157. return can_fd_dlc2len(can_fd_len2dlc(len));
  158. }
  159. #endif /* !_CAN_LENGTH_H */