diff options
Diffstat (limited to 'drivers/media/rc/ir-rc5-decoder.c')
| -rw-r--r-- | drivers/media/rc/ir-rc5-decoder.c | 189 |
1 files changed, 189 insertions, 0 deletions
diff --git a/drivers/media/rc/ir-rc5-decoder.c b/drivers/media/rc/ir-rc5-decoder.c new file mode 100644 index 000000000000..ebdba5539916 --- /dev/null +++ b/drivers/media/rc/ir-rc5-decoder.c @@ -0,0 +1,189 @@ +/* ir-rc5-decoder.c - handle RC5(x) IR Pulse/Space protocol + * + * Copyright (C) 2010 by Mauro Carvalho Chehab <mchehab@redhat.com> + * + * 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" + +#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; + + if (!(dev->raw->enabled_protocols & RC_TYPE_RC5)) + 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; + 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; + + IR_dprintk(1, "RC5X scancode 0x%06x (toggle: %u)\n", + scancode, toggle); + + } else { + /* RC5 */ + u8 command, system; + 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; + + IR_dprintk(1, "RC5 scancode 0x%04x (toggle: %u)\n", + scancode, toggle); + } + + rc_keydown(dev, 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_TYPE_RC5, + .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 <mchehab@redhat.com>"); +MODULE_AUTHOR("Red Hat Inc. (http://www.redhat.com)"); +MODULE_DESCRIPTION("RC5(x) IR protocol decoder"); |
