diff options
Diffstat (limited to 'drivers/media/rc/ir-nec-decoder.c')
| -rw-r--r-- | drivers/media/rc/ir-nec-decoder.c | 227 |
1 files changed, 227 insertions, 0 deletions
diff --git a/drivers/media/rc/ir-nec-decoder.c b/drivers/media/rc/ir-nec-decoder.c new file mode 100644 index 000000000..7b81fec08 --- /dev/null +++ b/drivers/media/rc/ir-nec-decoder.c @@ -0,0 +1,227 @@ +/* ir-nec-decoder.c - handle NEC 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. + */ + +#include <linux/bitrev.h> +#include <linux/module.h> +#include "rc-core-priv.h" + +#define NEC_NBITS 32 +#define NEC_UNIT 562500 /* ns */ +#define NEC_HEADER_PULSE (16 * NEC_UNIT) +#define NECX_HEADER_PULSE (8 * NEC_UNIT) /* Less common NEC variant */ +#define NEC_HEADER_SPACE (8 * NEC_UNIT) +#define NEC_REPEAT_SPACE (4 * NEC_UNIT) +#define NEC_BIT_PULSE (1 * NEC_UNIT) +#define NEC_BIT_0_SPACE (1 * NEC_UNIT) +#define NEC_BIT_1_SPACE (3 * NEC_UNIT) +#define NEC_TRAILER_PULSE (1 * NEC_UNIT) +#define NEC_TRAILER_SPACE (10 * NEC_UNIT) /* even longer in reality */ +#define NECX_REPEAT_BITS 1 + +enum nec_state { + STATE_INACTIVE, + STATE_HEADER_SPACE, + STATE_BIT_PULSE, + STATE_BIT_SPACE, + STATE_TRAILER_PULSE, + STATE_TRAILER_SPACE, +}; + +/** + * ir_nec_decode() - Decode one NEC pulse or space + * @dev: the struct rc_dev descriptor of the device + * @duration: the struct ir_raw_event descriptor of the pulse/space + * + * This function returns -EINVAL if the pulse violates the state machine + */ +static int ir_nec_decode(struct rc_dev *dev, struct ir_raw_event ev) +{ + struct nec_dec *data = &dev->raw->nec; + u32 scancode; + u8 address, not_address, command, not_command; + bool send_32bits = false; + + if (!(dev->enabled_protocols & RC_BIT_NEC)) + return 0; + + if (!is_timing_event(ev)) { + if (ev.reset) + data->state = STATE_INACTIVE; + return 0; + } + + IR_dprintk(2, "NEC decode started at state %d (%uus %s)\n", + data->state, TO_US(ev.duration), TO_STR(ev.pulse)); + + switch (data->state) { + + case STATE_INACTIVE: + if (!ev.pulse) + break; + + if (eq_margin(ev.duration, NEC_HEADER_PULSE, NEC_UNIT * 2)) { + data->is_nec_x = false; + data->necx_repeat = false; + } else if (eq_margin(ev.duration, NECX_HEADER_PULSE, NEC_UNIT / 2)) + data->is_nec_x = true; + else + break; + + data->count = 0; + data->state = STATE_HEADER_SPACE; + return 0; + + case STATE_HEADER_SPACE: + if (ev.pulse) + break; + + if (eq_margin(ev.duration, NEC_HEADER_SPACE, NEC_UNIT)) { + data->state = STATE_BIT_PULSE; + return 0; + } else if (eq_margin(ev.duration, NEC_REPEAT_SPACE, NEC_UNIT / 2)) { + if (!dev->keypressed) { + IR_dprintk(1, "Discarding last key repeat: event after key up\n"); + } else { + rc_repeat(dev); + IR_dprintk(1, "Repeat last key\n"); + data->state = STATE_TRAILER_PULSE; + } + return 0; + } + + break; + + case STATE_BIT_PULSE: + if (!ev.pulse) + break; + + if (!eq_margin(ev.duration, NEC_BIT_PULSE, NEC_UNIT / 2)) + break; + + data->state = STATE_BIT_SPACE; + return 0; + + case STATE_BIT_SPACE: + if (ev.pulse) + break; + + if (data->necx_repeat && data->count == NECX_REPEAT_BITS && + geq_margin(ev.duration, + NEC_TRAILER_SPACE, NEC_UNIT / 2)) { + IR_dprintk(1, "Repeat last key\n"); + rc_repeat(dev); + data->state = STATE_INACTIVE; + return 0; + + } else if (data->count > NECX_REPEAT_BITS) + data->necx_repeat = false; + + data->bits <<= 1; + if (eq_margin(ev.duration, NEC_BIT_1_SPACE, NEC_UNIT / 2)) + data->bits |= 1; + else if (!eq_margin(ev.duration, NEC_BIT_0_SPACE, NEC_UNIT / 2)) + break; + data->count++; + + if (data->count == NEC_NBITS) + data->state = STATE_TRAILER_PULSE; + else + data->state = STATE_BIT_PULSE; + + return 0; + + case STATE_TRAILER_PULSE: + if (!ev.pulse) + break; + + if (!eq_margin(ev.duration, NEC_TRAILER_PULSE, NEC_UNIT / 2)) + break; + + data->state = STATE_TRAILER_SPACE; + return 0; + + case STATE_TRAILER_SPACE: + if (ev.pulse) + break; + + if (!geq_margin(ev.duration, NEC_TRAILER_SPACE, NEC_UNIT / 2)) + break; + + address = bitrev8((data->bits >> 24) & 0xff); + not_address = bitrev8((data->bits >> 16) & 0xff); + command = bitrev8((data->bits >> 8) & 0xff); + not_command = bitrev8((data->bits >> 0) & 0xff); + + if ((command ^ not_command) != 0xff) { + IR_dprintk(1, "NEC checksum error: received 0x%08x\n", + data->bits); + send_32bits = true; + } + + if (send_32bits) { + /* NEC transport, but modified protocol, used by at + * least Apple and TiVo remotes */ + scancode = data->bits; + IR_dprintk(1, "NEC (modified) scancode 0x%08x\n", scancode); + } else if ((address ^ not_address) != 0xff) { + /* Extended NEC */ + scancode = address << 16 | + not_address << 8 | + command; + IR_dprintk(1, "NEC (Ext) scancode 0x%06x\n", scancode); + } else { + /* Normal NEC */ + scancode = address << 8 | command; + IR_dprintk(1, "NEC scancode 0x%04x\n", scancode); + } + + if (data->is_nec_x) + data->necx_repeat = true; + + rc_keydown(dev, RC_TYPE_NEC, scancode, 0); + data->state = STATE_INACTIVE; + return 0; + } + + IR_dprintk(1, "NEC decode failed at count %d state %d (%uus %s)\n", + data->count, data->state, TO_US(ev.duration), TO_STR(ev.pulse)); + data->state = STATE_INACTIVE; + return -EINVAL; +} + +static struct ir_raw_handler nec_handler = { + .protocols = RC_BIT_NEC, + .decode = ir_nec_decode, +}; + +static int __init ir_nec_decode_init(void) +{ + ir_raw_handler_register(&nec_handler); + + printk(KERN_INFO "IR NEC protocol handler initialized\n"); + return 0; +} + +static void __exit ir_nec_decode_exit(void) +{ + ir_raw_handler_unregister(&nec_handler); +} + +module_init(ir_nec_decode_init); +module_exit(ir_nec_decode_exit); + +MODULE_LICENSE("GPL"); +MODULE_AUTHOR("Mauro Carvalho Chehab"); +MODULE_AUTHOR("Red Hat Inc. (http://www.redhat.com)"); +MODULE_DESCRIPTION("NEC IR protocol decoder"); |