ir-xmp-decoder.c 5.6 KB

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  1. // SPDX-License-Identifier: GPL-2.0-only
  2. /* ir-xmp-decoder.c - handle XMP IR Pulse/Space protocol
  3. *
  4. * Copyright (C) 2014 by Marcel Mol
  5. *
  6. * - Based on info from http://www.hifi-remote.com
  7. * - Ignore Toggle=9 frames
  8. * - Ignore XMP-1 XMP-2 difference, always store 16 bit OBC
  9. */
  10. #include <linux/bitrev.h>
  11. #include <linux/module.h>
  12. #include "rc-core-priv.h"
  13. #define XMP_UNIT 136 /* us */
  14. #define XMP_LEADER 210 /* us */
  15. #define XMP_NIBBLE_PREFIX 760 /* us */
  16. #define XMP_HALFFRAME_SPACE 13800 /* us */
  17. /* should be 80ms but not all duration supliers can go that high */
  18. #define XMP_TRAILER_SPACE 20000
  19. enum xmp_state {
  20. STATE_INACTIVE,
  21. STATE_LEADER_PULSE,
  22. STATE_NIBBLE_SPACE,
  23. };
  24. /**
  25. * ir_xmp_decode() - Decode one XMP pulse or space
  26. * @dev: the struct rc_dev descriptor of the device
  27. * @ev: the struct ir_raw_event descriptor of the pulse/space
  28. *
  29. * This function returns -EINVAL if the pulse violates the state machine
  30. */
  31. static int ir_xmp_decode(struct rc_dev *dev, struct ir_raw_event ev)
  32. {
  33. struct xmp_dec *data = &dev->raw->xmp;
  34. if (!is_timing_event(ev)) {
  35. if (ev.reset)
  36. data->state = STATE_INACTIVE;
  37. return 0;
  38. }
  39. dev_dbg(&dev->dev, "XMP decode started at state %d %d (%uus %s)\n",
  40. data->state, data->count, ev.duration, TO_STR(ev.pulse));
  41. switch (data->state) {
  42. case STATE_INACTIVE:
  43. if (!ev.pulse)
  44. break;
  45. if (eq_margin(ev.duration, XMP_LEADER, XMP_UNIT / 2)) {
  46. data->count = 0;
  47. data->state = STATE_NIBBLE_SPACE;
  48. }
  49. return 0;
  50. case STATE_LEADER_PULSE:
  51. if (!ev.pulse)
  52. break;
  53. if (eq_margin(ev.duration, XMP_LEADER, XMP_UNIT / 2))
  54. data->state = STATE_NIBBLE_SPACE;
  55. return 0;
  56. case STATE_NIBBLE_SPACE:
  57. if (ev.pulse)
  58. break;
  59. if (geq_margin(ev.duration, XMP_TRAILER_SPACE, XMP_NIBBLE_PREFIX)) {
  60. int divider, i;
  61. u8 addr, subaddr, subaddr2, toggle, oem, obc1, obc2, sum1, sum2;
  62. u32 *n;
  63. u32 scancode;
  64. if (data->count != 16) {
  65. dev_dbg(&dev->dev, "received TRAILER period at index %d: %u\n",
  66. data->count, ev.duration);
  67. data->state = STATE_INACTIVE;
  68. return -EINVAL;
  69. }
  70. n = data->durations;
  71. /*
  72. * the 4th nibble should be 15 so base the divider on this
  73. * to transform durations into nibbles. Subtract 2000 from
  74. * the divider to compensate for fluctuations in the signal
  75. */
  76. divider = (n[3] - XMP_NIBBLE_PREFIX) / 15 - 2000;
  77. if (divider < 50) {
  78. dev_dbg(&dev->dev, "divider to small %d.\n",
  79. divider);
  80. data->state = STATE_INACTIVE;
  81. return -EINVAL;
  82. }
  83. /* convert to nibbles and do some sanity checks */
  84. for (i = 0; i < 16; i++)
  85. n[i] = (n[i] - XMP_NIBBLE_PREFIX) / divider;
  86. sum1 = (15 + n[0] + n[1] + n[2] + n[3] +
  87. n[4] + n[5] + n[6] + n[7]) % 16;
  88. sum2 = (15 + n[8] + n[9] + n[10] + n[11] +
  89. n[12] + n[13] + n[14] + n[15]) % 16;
  90. if (sum1 != 15 || sum2 != 15) {
  91. dev_dbg(&dev->dev, "checksum errors sum1=0x%X sum2=0x%X\n",
  92. sum1, sum2);
  93. data->state = STATE_INACTIVE;
  94. return -EINVAL;
  95. }
  96. subaddr = n[0] << 4 | n[2];
  97. subaddr2 = n[8] << 4 | n[11];
  98. oem = n[4] << 4 | n[5];
  99. addr = n[6] << 4 | n[7];
  100. toggle = n[10];
  101. obc1 = n[12] << 4 | n[13];
  102. obc2 = n[14] << 4 | n[15];
  103. if (subaddr != subaddr2) {
  104. dev_dbg(&dev->dev, "subaddress nibbles mismatch 0x%02X != 0x%02X\n",
  105. subaddr, subaddr2);
  106. data->state = STATE_INACTIVE;
  107. return -EINVAL;
  108. }
  109. if (oem != 0x44)
  110. dev_dbg(&dev->dev, "Warning: OEM nibbles 0x%02X. Expected 0x44\n",
  111. oem);
  112. scancode = addr << 24 | subaddr << 16 |
  113. obc1 << 8 | obc2;
  114. dev_dbg(&dev->dev, "XMP scancode 0x%06x\n", scancode);
  115. if (toggle == 0) {
  116. rc_keydown(dev, RC_PROTO_XMP, scancode, 0);
  117. } else {
  118. rc_repeat(dev);
  119. dev_dbg(&dev->dev, "Repeat last key\n");
  120. }
  121. data->state = STATE_INACTIVE;
  122. return 0;
  123. } else if (geq_margin(ev.duration, XMP_HALFFRAME_SPACE, XMP_NIBBLE_PREFIX)) {
  124. /* Expect 8 or 16 nibble pulses. 16 in case of 'final' frame */
  125. if (data->count == 16) {
  126. dev_dbg(&dev->dev, "received half frame pulse at index %d. Probably a final frame key-up event: %u\n",
  127. data->count, ev.duration);
  128. /*
  129. * TODO: for now go back to half frame position
  130. * so trailer can be found and key press
  131. * can be handled.
  132. */
  133. data->count = 8;
  134. }
  135. else if (data->count != 8)
  136. dev_dbg(&dev->dev, "received half frame pulse at index %d: %u\n",
  137. data->count, ev.duration);
  138. data->state = STATE_LEADER_PULSE;
  139. return 0;
  140. } else if (geq_margin(ev.duration, XMP_NIBBLE_PREFIX, XMP_UNIT)) {
  141. /* store nibble raw data, decode after trailer */
  142. if (data->count == 16) {
  143. dev_dbg(&dev->dev, "too many pulses (%d) ignoring: %u\n",
  144. data->count, ev.duration);
  145. data->state = STATE_INACTIVE;
  146. return -EINVAL;
  147. }
  148. data->durations[data->count] = ev.duration;
  149. data->count++;
  150. data->state = STATE_LEADER_PULSE;
  151. return 0;
  152. }
  153. break;
  154. }
  155. dev_dbg(&dev->dev, "XMP decode failed at count %d state %d (%uus %s)\n",
  156. data->count, data->state, ev.duration, TO_STR(ev.pulse));
  157. data->state = STATE_INACTIVE;
  158. return -EINVAL;
  159. }
  160. static struct ir_raw_handler xmp_handler = {
  161. .protocols = RC_PROTO_BIT_XMP,
  162. .decode = ir_xmp_decode,
  163. .min_timeout = XMP_TRAILER_SPACE,
  164. };
  165. static int __init ir_xmp_decode_init(void)
  166. {
  167. ir_raw_handler_register(&xmp_handler);
  168. printk(KERN_INFO "IR XMP protocol handler initialized\n");
  169. return 0;
  170. }
  171. static void __exit ir_xmp_decode_exit(void)
  172. {
  173. ir_raw_handler_unregister(&xmp_handler);
  174. }
  175. module_init(ir_xmp_decode_init);
  176. module_exit(ir_xmp_decode_exit);
  177. MODULE_LICENSE("GPL");
  178. MODULE_AUTHOR("Marcel Mol <marcel@mesa.nl>");
  179. MODULE_AUTHOR("MESA Consulting (http://www.mesa.nl)");
  180. MODULE_DESCRIPTION("XMP IR protocol decoder");