Stefan Wahren | 291ab06 | 2014-09-26 22:21:21 +0000 | [diff] [blame] | 1 | /* |
| 2 | * Copyright (c) 2011, 2012, Atheros Communications Inc. |
| 3 | * Copyright (c) 2014, I2SE GmbH |
| 4 | * |
| 5 | * Permission to use, copy, modify, and/or distribute this software |
| 6 | * for any purpose with or without fee is hereby granted, provided |
| 7 | * that the above copyright notice and this permission notice appear |
| 8 | * in all copies. |
| 9 | * |
| 10 | * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL |
| 11 | * WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED |
| 12 | * WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL |
| 13 | * THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR |
| 14 | * CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM |
| 15 | * LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, |
| 16 | * NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN |
| 17 | * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. |
| 18 | */ |
| 19 | |
| 20 | /* Atheros ethernet framing. Every Ethernet frame is surrounded |
| 21 | * by an atheros frame while transmitted over a serial channel; |
| 22 | */ |
| 23 | |
| 24 | #include <linux/kernel.h> |
| 25 | |
| 26 | #include "qca_framing.h" |
| 27 | |
| 28 | u16 |
| 29 | qcafrm_create_header(u8 *buf, u16 length) |
| 30 | { |
| 31 | __le16 len; |
| 32 | |
| 33 | if (!buf) |
| 34 | return 0; |
| 35 | |
| 36 | len = cpu_to_le16(length); |
| 37 | |
| 38 | buf[0] = 0xAA; |
| 39 | buf[1] = 0xAA; |
| 40 | buf[2] = 0xAA; |
| 41 | buf[3] = 0xAA; |
| 42 | buf[4] = len & 0xff; |
| 43 | buf[5] = (len >> 8) & 0xff; |
| 44 | buf[6] = 0; |
| 45 | buf[7] = 0; |
| 46 | |
| 47 | return QCAFRM_HEADER_LEN; |
| 48 | } |
| 49 | |
| 50 | u16 |
| 51 | qcafrm_create_footer(u8 *buf) |
| 52 | { |
| 53 | if (!buf) |
| 54 | return 0; |
| 55 | |
| 56 | buf[0] = 0x55; |
| 57 | buf[1] = 0x55; |
| 58 | return QCAFRM_FOOTER_LEN; |
| 59 | } |
| 60 | |
| 61 | /* Gather received bytes and try to extract a full ethernet frame by |
| 62 | * following a simple state machine. |
| 63 | * |
| 64 | * Return: QCAFRM_GATHER No ethernet frame fully received yet. |
| 65 | * QCAFRM_NOHEAD Header expected but not found. |
| 66 | * QCAFRM_INVLEN Atheros frame length is invalid |
| 67 | * QCAFRM_NOTAIL Footer expected but not found. |
| 68 | * > 0 Number of byte in the fully received |
| 69 | * Ethernet frame |
| 70 | */ |
| 71 | |
| 72 | s32 |
| 73 | qcafrm_fsm_decode(struct qcafrm_handle *handle, u8 *buf, u16 buf_len, u8 recv_byte) |
| 74 | { |
| 75 | s32 ret = QCAFRM_GATHER; |
| 76 | u16 len; |
| 77 | |
| 78 | switch (handle->state) { |
| 79 | case QCAFRM_HW_LEN0: |
| 80 | case QCAFRM_HW_LEN1: |
| 81 | /* by default, just go to next state */ |
| 82 | handle->state--; |
| 83 | |
| 84 | if (recv_byte != 0x00) { |
| 85 | /* first two bytes of length must be 0 */ |
| 86 | handle->state = QCAFRM_HW_LEN0; |
| 87 | } |
| 88 | break; |
| 89 | case QCAFRM_HW_LEN2: |
| 90 | case QCAFRM_HW_LEN3: |
| 91 | handle->state--; |
| 92 | break; |
| 93 | /* 4 bytes header pattern */ |
| 94 | case QCAFRM_WAIT_AA1: |
| 95 | case QCAFRM_WAIT_AA2: |
| 96 | case QCAFRM_WAIT_AA3: |
| 97 | case QCAFRM_WAIT_AA4: |
| 98 | if (recv_byte != 0xAA) { |
| 99 | ret = QCAFRM_NOHEAD; |
| 100 | handle->state = QCAFRM_HW_LEN0; |
| 101 | } else { |
| 102 | handle->state--; |
| 103 | } |
| 104 | break; |
| 105 | /* 2 bytes length. */ |
| 106 | /* Borrow offset field to hold length for now. */ |
| 107 | case QCAFRM_WAIT_LEN_BYTE0: |
| 108 | handle->offset = recv_byte; |
| 109 | handle->state = QCAFRM_WAIT_LEN_BYTE1; |
| 110 | break; |
| 111 | case QCAFRM_WAIT_LEN_BYTE1: |
| 112 | handle->offset = handle->offset | (recv_byte << 8); |
| 113 | handle->state = QCAFRM_WAIT_RSVD_BYTE1; |
| 114 | break; |
| 115 | case QCAFRM_WAIT_RSVD_BYTE1: |
| 116 | handle->state = QCAFRM_WAIT_RSVD_BYTE2; |
| 117 | break; |
| 118 | case QCAFRM_WAIT_RSVD_BYTE2: |
| 119 | len = handle->offset; |
| 120 | if (len > buf_len || len < QCAFRM_ETHMINLEN) { |
| 121 | ret = QCAFRM_INVLEN; |
| 122 | handle->state = QCAFRM_HW_LEN0; |
| 123 | } else { |
| 124 | handle->state = (enum qcafrm_state)(len + 1); |
| 125 | /* Remaining number of bytes. */ |
| 126 | handle->offset = 0; |
| 127 | } |
| 128 | break; |
| 129 | default: |
| 130 | /* Receiving Ethernet frame itself. */ |
| 131 | buf[handle->offset] = recv_byte; |
| 132 | handle->offset++; |
| 133 | handle->state--; |
| 134 | break; |
| 135 | case QCAFRM_WAIT_551: |
| 136 | if (recv_byte != 0x55) { |
| 137 | ret = QCAFRM_NOTAIL; |
| 138 | handle->state = QCAFRM_HW_LEN0; |
| 139 | } else { |
| 140 | handle->state = QCAFRM_WAIT_552; |
| 141 | } |
| 142 | break; |
| 143 | case QCAFRM_WAIT_552: |
| 144 | if (recv_byte != 0x55) { |
| 145 | ret = QCAFRM_NOTAIL; |
| 146 | handle->state = QCAFRM_HW_LEN0; |
| 147 | } else { |
| 148 | ret = handle->offset; |
| 149 | /* Frame is fully received. */ |
| 150 | handle->state = QCAFRM_HW_LEN0; |
| 151 | } |
| 152 | break; |
| 153 | } |
| 154 | |
| 155 | return ret; |
| 156 | } |