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");