1/* ir-rc5-sz-decoder.c - handle RC5 Streamzap IR Pulse/Space protocol 2 * 3 * Copyright (C) 2010 by Mauro Carvalho Chehab <mchehab@redhat.com> 4 * Copyright (C) 2010 by Jarod Wilson <jarod@redhat.com> 5 * 6 * This program is free software; you can redistribute it and/or modify 7 * it under the terms of the GNU General Public License as published by 8 * the Free Software Foundation version 2 of the License. 9 * 10 * This program is distributed in the hope that it will be useful, 11 * but WITHOUT ANY WARRANTY; without even the implied warranty of 12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 13 * GNU General Public License for more details. 14 */ 15 16/* 17 * This code handles the 15 bit RC5-ish protocol used by the Streamzap 18 * PC Remote. 19 * It considers a carrier of 36 kHz, with a total of 15 bits, where 20 * the first two bits are start bits, and a third one is a filing bit 21 */ 22 23#include "rc-core-priv.h" 24#include <linux/module.h> 25 26#define RC5_SZ_NBITS 15 27#define RC5_UNIT 888888 /* ns */ 28#define RC5_BIT_START (1 * RC5_UNIT) 29#define RC5_BIT_END (1 * RC5_UNIT) 30 31enum rc5_sz_state { 32 STATE_INACTIVE, 33 STATE_BIT_START, 34 STATE_BIT_END, 35 STATE_FINISHED, 36}; 37 38/** 39 * ir_rc5_sz_decode() - Decode one RC-5 Streamzap pulse or space 40 * @dev: the struct rc_dev descriptor of the device 41 * @ev: the struct ir_raw_event descriptor of the pulse/space 42 * 43 * This function returns -EINVAL if the pulse violates the state machine 44 */ 45static int ir_rc5_sz_decode(struct rc_dev *dev, struct ir_raw_event ev) 46{ 47 struct rc5_sz_dec *data = &dev->raw->rc5_sz; 48 u8 toggle, command, system; 49 u32 scancode; 50 51 if (!(dev->raw->enabled_protocols & RC_TYPE_RC5_SZ)) 52 return 0; 53 54 if (!is_timing_event(ev)) { 55 if (ev.reset) 56 data->state = STATE_INACTIVE; 57 return 0; 58 } 59 60 if (!geq_margin(ev.duration, RC5_UNIT, RC5_UNIT / 2)) 61 goto out; 62 63again: 64 IR_dprintk(2, "RC5-sz decode started at state %i (%uus %s)\n", 65 data->state, TO_US(ev.duration), TO_STR(ev.pulse)); 66 67 if (!geq_margin(ev.duration, RC5_UNIT, RC5_UNIT / 2)) 68 return 0; 69 70 switch (data->state) { 71 72 case STATE_INACTIVE: 73 if (!ev.pulse) 74 break; 75 76 data->state = STATE_BIT_START; 77 data->count = 1; 78 data->wanted_bits = RC5_SZ_NBITS; 79 decrease_duration(&ev, RC5_BIT_START); 80 goto again; 81 82 case STATE_BIT_START: 83 if (!eq_margin(ev.duration, RC5_BIT_START, RC5_UNIT / 2)) 84 break; 85 86 data->bits <<= 1; 87 if (!ev.pulse) 88 data->bits |= 1; 89 data->count++; 90 data->state = STATE_BIT_END; 91 return 0; 92 93 case STATE_BIT_END: 94 if (!is_transition(&ev, &dev->raw->prev_ev)) 95 break; 96 97 if (data->count == data->wanted_bits) 98 data->state = STATE_FINISHED; 99 else 100 data->state = STATE_BIT_START; 101 102 decrease_duration(&ev, RC5_BIT_END); 103 goto again; 104 105 case STATE_FINISHED: 106 if (ev.pulse) 107 break; 108 109 /* RC5-sz */ 110 command = (data->bits & 0x0003F) >> 0; 111 system = (data->bits & 0x02FC0) >> 6; 112 toggle = (data->bits & 0x01000) ? 1 : 0; 113 scancode = system << 6 | command; 114 115 IR_dprintk(1, "RC5-sz scancode 0x%04x (toggle: %u)\n", 116 scancode, toggle); 117 118 rc_keydown(dev, scancode, toggle); 119 data->state = STATE_INACTIVE; 120 return 0; 121 } 122 123out: 124 IR_dprintk(1, "RC5-sz decode failed at state %i (%uus %s)\n", 125 data->state, TO_US(ev.duration), TO_STR(ev.pulse)); 126 data->state = STATE_INACTIVE; 127 return -EINVAL; 128} 129 130static struct ir_raw_handler rc5_sz_handler = { 131 .protocols = RC_TYPE_RC5_SZ, 132 .decode = ir_rc5_sz_decode, 133}; 134 135static int __init ir_rc5_sz_decode_init(void) 136{ 137 ir_raw_handler_register(&rc5_sz_handler); 138 139 printk(KERN_INFO "IR RC5 (streamzap) protocol handler initialized\n"); 140 return 0; 141} 142 143static void __exit ir_rc5_sz_decode_exit(void) 144{ 145 ir_raw_handler_unregister(&rc5_sz_handler); 146} 147 148module_init(ir_rc5_sz_decode_init); 149module_exit(ir_rc5_sz_decode_exit); 150 151MODULE_LICENSE("GPL"); 152MODULE_AUTHOR("Jarod Wilson <jarod@redhat.com>"); 153MODULE_AUTHOR("Red Hat Inc. (http://www.redhat.com)"); 154MODULE_DESCRIPTION("RC5 (streamzap) IR protocol decoder"); 155