154 lines
3.8 KiB
C
154 lines
3.8 KiB
C
/* ir-rc5-sz-decoder.c - handle RC5 Streamzap IR Pulse/Space protocol
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*
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* Copyright (C) 2010 by Mauro Carvalho Chehab <mchehab@redhat.com>
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* Copyright (C) 2010 by Jarod Wilson <jarod@redhat.com>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation version 2 of the License.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*/
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/*
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* This code handles the 15 bit RC5-ish protocol used by the Streamzap
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* PC Remote.
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* It considers a carrier of 36 kHz, with a total of 15 bits, where
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* the first two bits are start bits, and a third one is a filing bit
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*/
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#include "rc-core-priv.h"
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#define RC5_SZ_NBITS 15
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#define RC5_UNIT 888888 /* ns */
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#define RC5_BIT_START (1 * RC5_UNIT)
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#define RC5_BIT_END (1 * RC5_UNIT)
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enum rc5_sz_state {
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STATE_INACTIVE,
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STATE_BIT_START,
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STATE_BIT_END,
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STATE_FINISHED,
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};
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/**
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* ir_rc5_sz_decode() - Decode one RC-5 Streamzap pulse or space
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* @dev: the struct rc_dev descriptor of the device
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* @ev: the struct ir_raw_event descriptor of the pulse/space
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*
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* This function returns -EINVAL if the pulse violates the state machine
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*/
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static int ir_rc5_sz_decode(struct rc_dev *dev, struct ir_raw_event ev)
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{
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struct rc5_sz_dec *data = &dev->raw->rc5_sz;
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u8 toggle, command, system;
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u32 scancode;
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if (!(dev->raw->enabled_protocols & RC_TYPE_RC5_SZ))
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return 0;
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if (!is_timing_event(ev)) {
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if (ev.reset)
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data->state = STATE_INACTIVE;
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return 0;
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}
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if (!geq_margin(ev.duration, RC5_UNIT, RC5_UNIT / 2))
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goto out;
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again:
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IR_dprintk(2, "RC5-sz decode started at state %i (%uus %s)\n",
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data->state, TO_US(ev.duration), TO_STR(ev.pulse));
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if (!geq_margin(ev.duration, RC5_UNIT, RC5_UNIT / 2))
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return 0;
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switch (data->state) {
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case STATE_INACTIVE:
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if (!ev.pulse)
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break;
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data->state = STATE_BIT_START;
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data->count = 1;
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data->wanted_bits = RC5_SZ_NBITS;
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decrease_duration(&ev, RC5_BIT_START);
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goto again;
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case STATE_BIT_START:
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if (!eq_margin(ev.duration, RC5_BIT_START, RC5_UNIT / 2))
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break;
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data->bits <<= 1;
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if (!ev.pulse)
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data->bits |= 1;
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data->count++;
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data->state = STATE_BIT_END;
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return 0;
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case STATE_BIT_END:
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if (!is_transition(&ev, &dev->raw->prev_ev))
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break;
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if (data->count == data->wanted_bits)
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data->state = STATE_FINISHED;
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else
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data->state = STATE_BIT_START;
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decrease_duration(&ev, RC5_BIT_END);
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goto again;
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case STATE_FINISHED:
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if (ev.pulse)
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break;
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/* RC5-sz */
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command = (data->bits & 0x0003F) >> 0;
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system = (data->bits & 0x02FC0) >> 6;
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toggle = (data->bits & 0x01000) ? 1 : 0;
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scancode = system << 6 | command;
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IR_dprintk(1, "RC5-sz scancode 0x%04x (toggle: %u)\n",
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scancode, toggle);
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rc_keydown(dev, scancode, toggle);
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data->state = STATE_INACTIVE;
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return 0;
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}
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out:
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IR_dprintk(1, "RC5-sz decode failed at state %i (%uus %s)\n",
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data->state, TO_US(ev.duration), TO_STR(ev.pulse));
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data->state = STATE_INACTIVE;
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return -EINVAL;
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}
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static struct ir_raw_handler rc5_sz_handler = {
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.protocols = RC_TYPE_RC5_SZ,
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.decode = ir_rc5_sz_decode,
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};
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static int __init ir_rc5_sz_decode_init(void)
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{
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ir_raw_handler_register(&rc5_sz_handler);
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printk(KERN_INFO "IR RC5 (streamzap) protocol handler initialized\n");
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return 0;
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}
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static void __exit ir_rc5_sz_decode_exit(void)
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{
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ir_raw_handler_unregister(&rc5_sz_handler);
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}
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module_init(ir_rc5_sz_decode_init);
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module_exit(ir_rc5_sz_decode_exit);
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MODULE_LICENSE("GPL");
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MODULE_AUTHOR("Jarod Wilson <jarod@redhat.com>");
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MODULE_AUTHOR("Red Hat Inc. (http://www.redhat.com)");
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MODULE_DESCRIPTION("RC5 (streamzap) IR protocol decoder");
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