media/rc/ir-jvc-decoder.c

0001 // SPDX-License-Identifier: GPL-2.0-only
0002 /* ir-jvc-decoder.c - handle JVC IR Pulse/Space protocol
0003  *
0004  * Copyright (C) 2010 by David Härdeman <david@hardeman.nu>
0005  */
0006
0007 #include <linux/bitrev.h>
0008 #include <linux/module.h>
0009 #include "rc-core-priv.h"
0010
0011 #define JVC_NBITS       16      /* dev(8) + func(8) */
0012 #define JVC_UNIT        525     /* us */
0013 #define JVC_HEADER_PULSE    (16 * JVC_UNIT) /* lack of header -> repeat */
0014 #define JVC_HEADER_SPACE    (8  * JVC_UNIT)
0015 #define JVC_BIT_PULSE       (1  * JVC_UNIT)
0016 #define JVC_BIT_0_SPACE     (1  * JVC_UNIT)
0017 #define JVC_BIT_1_SPACE     (3  * JVC_UNIT)
0018 #define JVC_TRAILER_PULSE   (1  * JVC_UNIT)
0019 #define JVC_TRAILER_SPACE   (35 * JVC_UNIT)
0020
0021 enum jvc_state {
0022     STATE_INACTIVE,
0023     STATE_HEADER_SPACE,
0024     STATE_BIT_PULSE,
0025     STATE_BIT_SPACE,
0026     STATE_TRAILER_PULSE,
0027     STATE_TRAILER_SPACE,
0028     STATE_CHECK_REPEAT,
0029 };
0030
0031 /**
0032  * ir_jvc_decode() - Decode one JVC pulse or space
0033  * @dev:    the struct rc_dev descriptor of the device
0034  * @ev:   the struct ir_raw_event descriptor of the pulse/space
0035  *
0036  * This function returns -EINVAL if the pulse violates the state machine
0037  */
0038 static int ir_jvc_decode(struct rc_dev *dev, struct ir_raw_event ev)
0039 {
0040     struct jvc_dec *data = &dev->raw->jvc;
0041
0042     if (!is_timing_event(ev)) {
0043         if (ev.overflow)
0044             data->state = STATE_INACTIVE;
0045         return 0;
0046     }
0047
0048     if (!geq_margin(ev.duration, JVC_UNIT, JVC_UNIT / 2))
0049         goto out;
0050
0051     dev_dbg(&dev->dev, "JVC decode started at state %d (%uus %s)\n",
0052         data->state, ev.duration, TO_STR(ev.pulse));
0053
0054 again:
0055     switch (data->state) {
0056
0057     case STATE_INACTIVE:
0058         if (!ev.pulse)
0059             break;
0060
0061         if (!eq_margin(ev.duration, JVC_HEADER_PULSE, JVC_UNIT / 2))
0062             break;
0063
0064         data->count = 0;
0065         data->first = true;
0066         data->toggle = !data->toggle;
0067         data->state = STATE_HEADER_SPACE;
0068         return 0;
0069
0070     case STATE_HEADER_SPACE:
0071         if (ev.pulse)
0072             break;
0073
0074         if (!eq_margin(ev.duration, JVC_HEADER_SPACE, JVC_UNIT / 2))
0075             break;
0076
0077         data->state = STATE_BIT_PULSE;
0078         return 0;
0079
0080     case STATE_BIT_PULSE:
0081         if (!ev.pulse)
0082             break;
0083
0084         if (!eq_margin(ev.duration, JVC_BIT_PULSE, JVC_UNIT / 2))
0085             break;
0086
0087         data->state = STATE_BIT_SPACE;
0088         return 0;
0089
0090     case STATE_BIT_SPACE:
0091         if (ev.pulse)
0092             break;
0093
0094         data->bits <<= 1;
0095         if (eq_margin(ev.duration, JVC_BIT_1_SPACE, JVC_UNIT / 2)) {
0096             data->bits |= 1;
0097             decrease_duration(&ev, JVC_BIT_1_SPACE);
0098         } else if (eq_margin(ev.duration, JVC_BIT_0_SPACE, JVC_UNIT / 2))
0099             decrease_duration(&ev, JVC_BIT_0_SPACE);
0100         else
0101             break;
0102         data->count++;
0103
0104         if (data->count == JVC_NBITS)
0105             data->state = STATE_TRAILER_PULSE;
0106         else
0107             data->state = STATE_BIT_PULSE;
0108         return 0;
0109
0110     case STATE_TRAILER_PULSE:
0111         if (!ev.pulse)
0112             break;
0113
0114         if (!eq_margin(ev.duration, JVC_TRAILER_PULSE, JVC_UNIT / 2))
0115             break;
0116
0117         data->state = STATE_TRAILER_SPACE;
0118         return 0;
0119
0120     case STATE_TRAILER_SPACE:
0121         if (ev.pulse)
0122             break;
0123
0124         if (!geq_margin(ev.duration, JVC_TRAILER_SPACE, JVC_UNIT / 2))
0125             break;
0126
0127         if (data->first) {
0128             u32 scancode;
0129             scancode = (bitrev8((data->bits >> 8) & 0xff) << 8) |
0130                    (bitrev8((data->bits >> 0) & 0xff) << 0);
0131             dev_dbg(&dev->dev, "JVC scancode 0x%04x\n", scancode);
0132             rc_keydown(dev, RC_PROTO_JVC, scancode, data->toggle);
0133             data->first = false;
0134             data->old_bits = data->bits;
0135         } else if (data->bits == data->old_bits) {
0136             dev_dbg(&dev->dev, "JVC repeat\n");
0137             rc_repeat(dev);
0138         } else {
0139             dev_dbg(&dev->dev, "JVC invalid repeat msg\n");
0140             break;
0141         }
0142
0143         data->count = 0;
0144         data->state = STATE_CHECK_REPEAT;
0145         return 0;
0146
0147     case STATE_CHECK_REPEAT:
0148         if (!ev.pulse)
0149             break;
0150
0151         if (eq_margin(ev.duration, JVC_HEADER_PULSE, JVC_UNIT / 2))
0152             data->state = STATE_INACTIVE;
0153   else
0154             data->state = STATE_BIT_PULSE;
0155         goto again;
0156     }
0157
0158 out:
0159     dev_dbg(&dev->dev, "JVC decode failed at state %d (%uus %s)\n",
0160         data->state, ev.duration, TO_STR(ev.pulse));
0161     data->state = STATE_INACTIVE;
0162     return -EINVAL;
0163 }
0164
0165 static const struct ir_raw_timings_pd ir_jvc_timings = {
0166     .header_pulse  = JVC_HEADER_PULSE,
0167     .header_space  = JVC_HEADER_SPACE,
0168     .bit_pulse     = JVC_BIT_PULSE,
0169     .bit_space[0]  = JVC_BIT_0_SPACE,
0170     .bit_space[1]  = JVC_BIT_1_SPACE,
0171     .trailer_pulse = JVC_TRAILER_PULSE,
0172     .trailer_space = JVC_TRAILER_SPACE,
0173     .msb_first     = 1,
0174 };
0175
0176 /**
0177  * ir_jvc_encode() - Encode a scancode as a stream of raw events
0178  *
0179  * @protocol:   protocol to encode
0180  * @scancode:   scancode to encode
0181  * @events: array of raw ir events to write into
0182  * @max:    maximum size of @events
0183  *
0184  * Returns: The number of events written.
0185  *      -ENOBUFS if there isn't enough space in the array to fit the
0186  *      encoding. In this case all @max events will have been written.
0187  */
0188 static int ir_jvc_encode(enum rc_proto protocol, u32 scancode,
0189              struct ir_raw_event *events, unsigned int max)
0190 {
0191     struct ir_raw_event *e = events;
0192     int ret;
0193     u32 raw = (bitrev8((scancode >> 8) & 0xff) << 8) |
0194           (bitrev8((scancode >> 0) & 0xff) << 0);
0195
0196     ret = ir_raw_gen_pd(&e, max, &ir_jvc_timings, JVC_NBITS, raw);
0197     if (ret < 0)
0198         return ret;
0199
0200     return e - events;
0201 }
0202
0203 static struct ir_raw_handler jvc_handler = {
0204     .protocols  = RC_PROTO_BIT_JVC,
0205     .decode     = ir_jvc_decode,
0206     .encode     = ir_jvc_encode,
0207     .carrier    = 38000,
0208     .min_timeout    = JVC_TRAILER_SPACE,
0209 };
0210
0211 static int __init ir_jvc_decode_init(void)
0212 {
0213     ir_raw_handler_register(&jvc_handler);
0214
0215     printk(KERN_INFO "IR JVC protocol handler initialized\n");
0216     return 0;
0217 }
0218
0219 static void __exit ir_jvc_decode_exit(void)
0220 {
0221     ir_raw_handler_unregister(&jvc_handler);
0222 }
0223
0224 module_init(ir_jvc_decode_init);
0225 module_exit(ir_jvc_decode_exit);
0226
0227 MODULE_LICENSE("GPL");
0228 MODULE_AUTHOR("David Härdeman <david@hardeman.nu>");
0229 MODULE_DESCRIPTION("JVC IR protocol decoder");