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path: root/drivers/media/rc/ir-rc6-decoder.c
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Diffstat (limited to 'drivers/media/rc/ir-rc6-decoder.c')
-rw-r--r--drivers/media/rc/ir-rc6-decoder.c280
1 files changed, 280 insertions, 0 deletions
diff --git a/drivers/media/rc/ir-rc6-decoder.c b/drivers/media/rc/ir-rc6-decoder.c
new file mode 100644
index 000000000000..755dafa3871b
--- /dev/null
+++ b/drivers/media/rc/ir-rc6-decoder.c
@@ -0,0 +1,280 @@
+/* ir-rc6-decoder.c - A decoder for the RC6 IR protocol
+ *
+ * Copyright (C) 2010 by David Härdeman <david@hardeman.nu>
+ *
+ * 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 "rc-core-priv.h"
+
+/*
+ * This decoder currently supports:
+ * RC6-0-16 (standard toggle bit in header)
+ * RC6-6A-24 (no toggle bit)
+ * RC6-6A-32 (MCE version with toggle bit in body)
+ */
+
+#define RC6_UNIT 444444 /* us */
+#define RC6_HEADER_NBITS 4 /* not including toggle bit */
+#define RC6_0_NBITS 16
+#define RC6_6A_SMALL_NBITS 24
+#define RC6_6A_LARGE_NBITS 32
+#define RC6_PREFIX_PULSE (6 * RC6_UNIT)
+#define RC6_PREFIX_SPACE (2 * RC6_UNIT)
+#define RC6_BIT_START (1 * RC6_UNIT)
+#define RC6_BIT_END (1 * RC6_UNIT)
+#define RC6_TOGGLE_START (2 * RC6_UNIT)
+#define RC6_TOGGLE_END (2 * RC6_UNIT)
+#define RC6_MODE_MASK 0x07 /* for the header bits */
+#define RC6_STARTBIT_MASK 0x08 /* for the header bits */
+#define RC6_6A_MCE_TOGGLE_MASK 0x8000 /* for the body bits */
+
+enum rc6_mode {
+ RC6_MODE_0,
+ RC6_MODE_6A,
+ RC6_MODE_UNKNOWN,
+};
+
+enum rc6_state {
+ STATE_INACTIVE,
+ STATE_PREFIX_SPACE,
+ STATE_HEADER_BIT_START,
+ STATE_HEADER_BIT_END,
+ STATE_TOGGLE_START,
+ STATE_TOGGLE_END,
+ STATE_BODY_BIT_START,
+ STATE_BODY_BIT_END,
+ STATE_FINISHED,
+};
+
+static enum rc6_mode rc6_mode(struct rc6_dec *data)
+{
+ switch (data->header & RC6_MODE_MASK) {
+ case 0:
+ return RC6_MODE_0;
+ case 6:
+ if (!data->toggle)
+ return RC6_MODE_6A;
+ /* fall through */
+ default:
+ return RC6_MODE_UNKNOWN;
+ }
+}
+
+/**
+ * ir_rc6_decode() - Decode one RC6 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_rc6_decode(struct rc_dev *dev, struct ir_raw_event ev)
+{
+ struct rc6_dec *data = &dev->raw->rc6;
+ u32 scancode;
+ u8 toggle;
+
+ if (!(dev->raw->enabled_protocols & RC_TYPE_RC6))
+ return 0;
+
+ if (!is_timing_event(ev)) {
+ if (ev.reset)
+ data->state = STATE_INACTIVE;
+ return 0;
+ }
+
+ if (!geq_margin(ev.duration, RC6_UNIT, RC6_UNIT / 2))
+ goto out;
+
+again:
+ IR_dprintk(2, "RC6 decode started at state %i (%uus %s)\n",
+ data->state, TO_US(ev.duration), TO_STR(ev.pulse));
+
+ if (!geq_margin(ev.duration, RC6_UNIT, RC6_UNIT / 2))
+ return 0;
+
+ switch (data->state) {
+
+ case STATE_INACTIVE:
+ if (!ev.pulse)
+ break;
+
+ /* Note: larger margin on first pulse since each RC6_UNIT
+ is quite short and some hardware takes some time to
+ adjust to the signal */
+ if (!eq_margin(ev.duration, RC6_PREFIX_PULSE, RC6_UNIT))
+ break;
+
+ data->state = STATE_PREFIX_SPACE;
+ data->count = 0;
+ return 0;
+
+ case STATE_PREFIX_SPACE:
+ if (ev.pulse)
+ break;
+
+ if (!eq_margin(ev.duration, RC6_PREFIX_SPACE, RC6_UNIT / 2))
+ break;
+
+ data->state = STATE_HEADER_BIT_START;
+ return 0;
+
+ case STATE_HEADER_BIT_START:
+ if (!eq_margin(ev.duration, RC6_BIT_START, RC6_UNIT / 2))
+ break;
+
+ data->header <<= 1;
+ if (ev.pulse)
+ data->header |= 1;
+ data->count++;
+ data->state = STATE_HEADER_BIT_END;
+ return 0;
+
+ case STATE_HEADER_BIT_END:
+ if (!is_transition(&ev, &dev->raw->prev_ev))
+ break;
+
+ if (data->count == RC6_HEADER_NBITS)
+ data->state = STATE_TOGGLE_START;
+ else
+ data->state = STATE_HEADER_BIT_START;
+
+ decrease_duration(&ev, RC6_BIT_END);
+ goto again;
+
+ case STATE_TOGGLE_START:
+ if (!eq_margin(ev.duration, RC6_TOGGLE_START, RC6_UNIT / 2))
+ break;
+
+ data->toggle = ev.pulse;
+ data->state = STATE_TOGGLE_END;
+ return 0;
+
+ case STATE_TOGGLE_END:
+ if (!is_transition(&ev, &dev->raw->prev_ev) ||
+ !geq_margin(ev.duration, RC6_TOGGLE_END, RC6_UNIT / 2))
+ break;
+
+ if (!(data->header & RC6_STARTBIT_MASK)) {
+ IR_dprintk(1, "RC6 invalid start bit\n");
+ break;
+ }
+
+ data->state = STATE_BODY_BIT_START;
+ decrease_duration(&ev, RC6_TOGGLE_END);
+ data->count = 0;
+
+ switch (rc6_mode(data)) {
+ case RC6_MODE_0:
+ data->wanted_bits = RC6_0_NBITS;
+ break;
+ case RC6_MODE_6A:
+ /* This might look weird, but we basically
+ check the value of the first body bit to
+ determine the number of bits in mode 6A */
+ if ((!ev.pulse && !geq_margin(ev.duration, RC6_UNIT, RC6_UNIT / 2)) ||
+ geq_margin(ev.duration, RC6_UNIT, RC6_UNIT / 2))
+ data->wanted_bits = RC6_6A_LARGE_NBITS;
+ else
+ data->wanted_bits = RC6_6A_SMALL_NBITS;
+ break;
+ default:
+ IR_dprintk(1, "RC6 unknown mode\n");
+ goto out;
+ }
+ goto again;
+
+ case STATE_BODY_BIT_START:
+ if (!eq_margin(ev.duration, RC6_BIT_START, RC6_UNIT / 2))
+ break;
+
+ data->body <<= 1;
+ if (ev.pulse)
+ data->body |= 1;
+ data->count++;
+ data->state = STATE_BODY_BIT_END;
+ return 0;
+
+ case STATE_BODY_BIT_END:
+ if (!is_transition(&ev, &dev->raw->prev_ev))
+ break;
+
+ if (data->count == data->wanted_bits)
+ data->state = STATE_FINISHED;
+ else
+ data->state = STATE_BODY_BIT_START;
+
+ decrease_duration(&ev, RC6_BIT_END);
+ goto again;
+
+ case STATE_FINISHED:
+ if (ev.pulse)
+ break;
+
+ switch (rc6_mode(data)) {
+ case RC6_MODE_0:
+ scancode = data->body & 0xffff;
+ toggle = data->toggle;
+ IR_dprintk(1, "RC6(0) scancode 0x%04x (toggle: %u)\n",
+ scancode, toggle);
+ break;
+ case RC6_MODE_6A:
+ if (data->wanted_bits == RC6_6A_LARGE_NBITS) {
+ toggle = data->body & RC6_6A_MCE_TOGGLE_MASK ? 1 : 0;
+ scancode = data->body & ~RC6_6A_MCE_TOGGLE_MASK;
+ } else {
+ toggle = 0;
+ scancode = data->body & 0xffffff;
+ }
+
+ IR_dprintk(1, "RC6(6A) scancode 0x%08x (toggle: %u)\n",
+ scancode, toggle);
+ break;
+ default:
+ IR_dprintk(1, "RC6 unknown mode\n");
+ goto out;
+ }
+
+ rc_keydown(dev, scancode, toggle);
+ data->state = STATE_INACTIVE;
+ return 0;
+ }
+
+out:
+ IR_dprintk(1, "RC6 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 rc6_handler = {
+ .protocols = RC_TYPE_RC6,
+ .decode = ir_rc6_decode,
+};
+
+static int __init ir_rc6_decode_init(void)
+{
+ ir_raw_handler_register(&rc6_handler);
+
+ printk(KERN_INFO "IR RC6 protocol handler initialized\n");
+ return 0;
+}
+
+static void __exit ir_rc6_decode_exit(void)
+{
+ ir_raw_handler_unregister(&rc6_handler);
+}
+
+module_init(ir_rc6_decode_init);
+module_exit(ir_rc6_decode_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("David Härdeman <david@hardeman.nu>");
+MODULE_DESCRIPTION("RC6 IR protocol decoder");
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-26 08:58:36 +0000