| /* ir-rc5-decoder.c - handle RC5(x) IR Pulse/Space protocol |
| * |
| * Copyright (C) 2010 by Mauro Carvalho Chehab |
| * |
| * This program is free software; you can redistribute it and/or modify |
| * it under the terms of the GNU General Public License as published by |
| * the Free Software Foundation version 2 of the License. |
| * |
| * This program is distributed in the hope that it will be useful, |
| * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| * GNU General Public License for more details. |
| */ |
| |
| /* |
| * This code handles 14 bits RC5 protocols and 20 bits RC5x protocols. |
| * There are other variants that use a different number of bits. |
| * This is currently unsupported. |
| * It considers a carrier of 36 kHz, with a total of 14/20 bits, where |
| * the first two bits are start bits, and a third one is a filing bit |
| */ |
| |
| #include "rc-core-priv.h" |
| #include <linux/module.h> |
| |
| #define RC5_NBITS 14 |
| #define RC5X_NBITS 20 |
| #define CHECK_RC5X_NBITS 8 |
| #define RC5_UNIT 888888 /* ns */ |
| #define RC5_BIT_START (1 * RC5_UNIT) |
| #define RC5_BIT_END (1 * RC5_UNIT) |
| #define RC5X_SPACE (4 * RC5_UNIT) |
| |
| enum rc5_state { |
| STATE_INACTIVE, |
| STATE_BIT_START, |
| STATE_BIT_END, |
| STATE_CHECK_RC5X, |
| STATE_FINISHED, |
| }; |
| |
| /** |
| * ir_rc5_decode() - Decode one RC-5 pulse or space |
| * @dev: the struct rc_dev descriptor of the device |
| * @ev: the struct ir_raw_event descriptor of the pulse/space |
| * |
| * This function returns -EINVAL if the pulse violates the state machine |
| */ |
| static int ir_rc5_decode(struct rc_dev *dev, struct ir_raw_event ev) |
| { |
| struct rc5_dec *data = &dev->raw->rc5; |
| u8 toggle; |
| u32 scancode; |
| enum rc_type protocol; |
| |
| if (!rc_protocols_enabled(dev, RC_BIT_RC5 | RC_BIT_RC5X)) |
| return 0; |
| |
| if (!is_timing_event(ev)) { |
| if (ev.reset) |
| data->state = STATE_INACTIVE; |
| return 0; |
| } |
| |
| if (!geq_margin(ev.duration, RC5_UNIT, RC5_UNIT / 2)) |
| goto out; |
| |
| again: |
| IR_dprintk(2, "RC5(x) decode started at state %i (%uus %s)\n", |
| data->state, TO_US(ev.duration), TO_STR(ev.pulse)); |
| |
| if (!geq_margin(ev.duration, RC5_UNIT, RC5_UNIT / 2)) |
| return 0; |
| |
| switch (data->state) { |
| |
| case STATE_INACTIVE: |
| if (!ev.pulse) |
| break; |
| |
| data->state = STATE_BIT_START; |
| data->count = 1; |
| /* We just need enough bits to get to STATE_CHECK_RC5X */ |
| data->wanted_bits = RC5X_NBITS; |
| decrease_duration(&ev, RC5_BIT_START); |
| goto again; |
| |
| case STATE_BIT_START: |
| if (!eq_margin(ev.duration, RC5_BIT_START, RC5_UNIT / 2)) |
| break; |
| |
| data->bits <<= 1; |
| if (!ev.pulse) |
| data->bits |= 1; |
| data->count++; |
| data->state = STATE_BIT_END; |
| return 0; |
| |
| case STATE_BIT_END: |
| if (!is_transition(&ev, &dev->raw->prev_ev)) |
| break; |
| |
| if (data->count == data->wanted_bits) |
| data->state = STATE_FINISHED; |
| else if (data->count == CHECK_RC5X_NBITS) |
| data->state = STATE_CHECK_RC5X; |
| else |
| data->state = STATE_BIT_START; |
| |
| decrease_duration(&ev, RC5_BIT_END); |
| goto again; |
| |
| case STATE_CHECK_RC5X: |
| if (!ev.pulse && geq_margin(ev.duration, RC5X_SPACE, RC5_UNIT / 2)) { |
| /* RC5X */ |
| data->wanted_bits = RC5X_NBITS; |
| decrease_duration(&ev, RC5X_SPACE); |
| } else { |
| /* RC5 */ |
| data->wanted_bits = RC5_NBITS; |
| } |
| data->state = STATE_BIT_START; |
| goto again; |
| |
| case STATE_FINISHED: |
| if (ev.pulse) |
| break; |
| |
| if (data->wanted_bits == RC5X_NBITS) { |
| /* RC5X */ |
| u8 xdata, command, system; |
| if (!rc_protocols_enabled(dev, RC_BIT_RC5X)) { |
| data->state = STATE_INACTIVE; |
| return 0; |
| } |
| xdata = (data->bits & 0x0003F) >> 0; |
| command = (data->bits & 0x00FC0) >> 6; |
| system = (data->bits & 0x1F000) >> 12; |
| toggle = (data->bits & 0x20000) ? 1 : 0; |
| command += (data->bits & 0x01000) ? 0 : 0x40; |
| scancode = system << 16 | command << 8 | xdata; |
| protocol = RC_TYPE_RC5X; |
| |
| IR_dprintk(1, "RC5X scancode 0x%06x (toggle: %u)\n", |
| scancode, toggle); |
| |
| } else { |
| /* RC5 */ |
| u8 command, system; |
| if (!rc_protocols_enabled(dev, RC_BIT_RC5)) { |
| data->state = STATE_INACTIVE; |
| return 0; |
| } |
| command = (data->bits & 0x0003F) >> 0; |
| system = (data->bits & 0x007C0) >> 6; |
| toggle = (data->bits & 0x00800) ? 1 : 0; |
| command += (data->bits & 0x01000) ? 0 : 0x40; |
| scancode = system << 8 | command; |
| protocol = RC_TYPE_RC5; |
| |
| IR_dprintk(1, "RC5 scancode 0x%04x (toggle: %u)\n", |
| scancode, toggle); |
| } |
| |
| rc_keydown(dev, protocol, scancode, toggle); |
| data->state = STATE_INACTIVE; |
| return 0; |
| } |
| |
| out: |
| IR_dprintk(1, "RC5(x) decode failed at state %i (%uus %s)\n", |
| data->state, TO_US(ev.duration), TO_STR(ev.pulse)); |
| data->state = STATE_INACTIVE; |
| return -EINVAL; |
| } |
| |
| static struct ir_raw_handler rc5_handler = { |
| .protocols = RC_BIT_RC5 | RC_BIT_RC5X, |
| .decode = ir_rc5_decode, |
| }; |
| |
| static int __init ir_rc5_decode_init(void) |
| { |
| ir_raw_handler_register(&rc5_handler); |
| |
| printk(KERN_INFO "IR RC5(x) protocol handler initialized\n"); |
| return 0; |
| } |
| |
| static void __exit ir_rc5_decode_exit(void) |
| { |
| ir_raw_handler_unregister(&rc5_handler); |
| } |
| |
| module_init(ir_rc5_decode_init); |
| module_exit(ir_rc5_decode_exit); |
| |
| MODULE_LICENSE("GPL"); |
| MODULE_AUTHOR("Mauro Carvalho Chehab"); |
| MODULE_AUTHOR("Red Hat Inc. (http://www.redhat.com)"); |
| MODULE_DESCRIPTION("RC5(x) IR protocol decoder"); |