1 files changed, 407 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 000000000..0657ad5ee
--- /dev/null
+++ b/drivers/media/rc/ir-rc6-decoder.c
@@ -0,0 +1,407 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/* ir-rc6-decoder.c - A decoder for the RC6 IR protocol
+ *
+ * Copyright (C) 2010 by David Härdeman <david@hardeman.nu>
+ */
+
+#include "rc-core-priv.h"
+#include <linux/module.h>
+
+/*
+ * This decoder currently supports:
+ * RC6-0-16	(standard toggle bit in header)
+ * RC6-6A-20	(no toggle bit)
+ * RC6-6A-24	(no toggle bit)
+ * RC6-6A-32	(MCE version with toggle bit in body)
+ */
+
+#define RC6_UNIT		444	/* microseconds */
+#define RC6_HEADER_NBITS	4	/* not including toggle bit */
+#define RC6_0_NBITS		16
+#define RC6_6A_32_NBITS		32
+#define RC6_6A_NBITS		128	/* Variable 8..128 */
+#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_SUFFIX_SPACE	(6 * 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 */
+#define RC6_6A_LCC_MASK		0xffff0000 /* RC6-6A-32 long customer code mask */
+#define RC6_6A_MCE_CC		0x800f0000 /* MCE customer code */
+#define RC6_6A_ZOTAC_CC		0x80340000 /* Zotac customer code */
+#define RC6_6A_KATHREIN_CC	0x80460000 /* Kathrein RCU-676 customer code */
+#ifndef CHAR_BIT
+#define CHAR_BIT 8	/* Normally in <limits.h> */
+#endif
+
+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;
+		fallthrough;
+	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;
+	enum rc_proto protocol;
+
+	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:
+	dev_dbg(&dev->dev, "RC6 decode started at state %i (%uus %s)\n",
+		data->state, 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;
+		data->header = 0;
+		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 (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 (!(data->header & RC6_STARTBIT_MASK)) {
+			dev_dbg(&dev->dev, "RC6 invalid start bit\n");
+			break;
+		}
+
+		data->state = STATE_BODY_BIT_START;
+		decrease_duration(&ev, RC6_TOGGLE_END);
+		data->count = 0;
+		data->body = 0;
+
+		switch (rc6_mode(data)) {
+		case RC6_MODE_0:
+			data->wanted_bits = RC6_0_NBITS;
+			break;
+		case RC6_MODE_6A:
+			data->wanted_bits = RC6_6A_NBITS;
+			break;
+		default:
+			dev_dbg(&dev->dev, "RC6 unknown mode\n");
+			goto out;
+		}
+		goto again;
+
+	case STATE_BODY_BIT_START:
+		if (eq_margin(ev.duration, RC6_BIT_START, RC6_UNIT / 2)) {
+			/* Discard LSB's that won't fit in data->body */
+			if (data->count++ < CHAR_BIT * sizeof data->body) {
+				data->body <<= 1;
+				if (ev.pulse)
+					data->body |= 1;
+			}
+			data->state = STATE_BODY_BIT_END;
+			return 0;
+		} else if (RC6_MODE_6A == rc6_mode(data) && !ev.pulse &&
+				geq_margin(ev.duration, RC6_SUFFIX_SPACE, RC6_UNIT / 2)) {
+			data->state = STATE_FINISHED;
+			goto again;
+		}
+		break;
+
+	case STATE_BODY_BIT_END:
+		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;
+			toggle = data->toggle;
+			protocol = RC_PROTO_RC6_0;
+			dev_dbg(&dev->dev, "RC6(0) scancode 0x%04x (toggle: %u)\n",
+				scancode, toggle);
+			break;
+
+		case RC6_MODE_6A:
+			if (data->count > CHAR_BIT * sizeof data->body) {
+				dev_dbg(&dev->dev, "RC6 too many (%u) data bits\n",
+					data->count);
+				goto out;
+			}
+
+			scancode = data->body;
+			switch (data->count) {
+			case 20:
+				protocol = RC_PROTO_RC6_6A_20;
+				toggle = 0;
+				break;
+			case 24:
+				protocol = RC_PROTO_RC6_6A_24;
+				toggle = 0;
+				break;
+			case 32:
+				switch (scancode & RC6_6A_LCC_MASK) {
+				case RC6_6A_MCE_CC:
+				case RC6_6A_KATHREIN_CC:
+				case RC6_6A_ZOTAC_CC:
+					protocol = RC_PROTO_RC6_MCE;
+					toggle = !!(scancode & RC6_6A_MCE_TOGGLE_MASK);
+					scancode &= ~RC6_6A_MCE_TOGGLE_MASK;
+					break;
+				default:
+					protocol = RC_PROTO_RC6_6A_32;
+					toggle = 0;
+					break;
+				}
+				break;
+			default:
+				dev_dbg(&dev->dev, "RC6(6A) unsupported length\n");
+				goto out;
+			}
+
+			dev_dbg(&dev->dev, "RC6(6A) proto 0x%04x, scancode 0x%08x (toggle: %u)\n",
+				protocol, scancode, toggle);
+			break;
+		default:
+			dev_dbg(&dev->dev, "RC6 unknown mode\n");
+			goto out;
+		}
+
+		rc_keydown(dev, protocol, scancode, toggle);
+		data->state = STATE_INACTIVE;
+		return 0;
+	}
+
+out:
+	dev_dbg(&dev->dev, "RC6 decode failed at state %i (%uus %s)\n",
+		data->state, ev.duration, TO_STR(ev.pulse));
+	data->state = STATE_INACTIVE;
+	return -EINVAL;
+}
+
+static const struct ir_raw_timings_manchester ir_rc6_timings[4] = {
+	{
+		.leader_pulse		= RC6_PREFIX_PULSE,
+		.leader_space		= RC6_PREFIX_SPACE,
+		.clock			= RC6_UNIT,
+		.invert			= 1,
+	},
+	{
+		.clock			= RC6_UNIT * 2,
+		.invert			= 1,
+	},
+	{
+		.clock			= RC6_UNIT,
+		.invert			= 1,
+		.trailer_space		= RC6_SUFFIX_SPACE,
+	},
+};
+
+/**
+ * ir_rc6_encode() - Encode a scancode as a stream of raw events
+ *
+ * @protocol:	protocol to encode
+ * @scancode:	scancode to encode
+ * @events:	array of raw ir events to write into
+ * @max:	maximum size of @events
+ *
+ * Returns:	The number of events written.
+ *		-ENOBUFS if there isn't enough space in the array to fit the
+ *		encoding. In this case all @max events will have been written.
+ *		-EINVAL if the scancode is ambiguous or invalid.
+ */
+static int ir_rc6_encode(enum rc_proto protocol, u32 scancode,
+			 struct ir_raw_event *events, unsigned int max)
+{
+	int ret;
+	struct ir_raw_event *e = events;
+
+	if (protocol == RC_PROTO_RC6_0) {
+		/* Modulate the header (Start Bit & Mode-0) */
+		ret = ir_raw_gen_manchester(&e, max - (e - events),
+					    &ir_rc6_timings[0],
+					    RC6_HEADER_NBITS, (1 << 3));
+		if (ret < 0)
+			return ret;
+
+		/* Modulate Trailer Bit */
+		ret = ir_raw_gen_manchester(&e, max - (e - events),
+					    &ir_rc6_timings[1], 1, 0);
+		if (ret < 0)
+			return ret;
+
+		/* Modulate rest of the data */
+		ret = ir_raw_gen_manchester(&e, max - (e - events),
+					    &ir_rc6_timings[2], RC6_0_NBITS,
+					    scancode);
+		if (ret < 0)
+			return ret;
+
+	} else {
+		int bits;
+
+		switch (protocol) {
+		case RC_PROTO_RC6_MCE:
+		case RC_PROTO_RC6_6A_32:
+			bits = 32;
+			break;
+		case RC_PROTO_RC6_6A_24:
+			bits = 24;
+			break;
+		case RC_PROTO_RC6_6A_20:
+			bits = 20;
+			break;
+		default:
+			return -EINVAL;
+		}
+
+		/* Modulate the header (Start Bit & Header-version 6 */
+		ret = ir_raw_gen_manchester(&e, max - (e - events),
+					    &ir_rc6_timings[0],
+					    RC6_HEADER_NBITS, (1 << 3 | 6));
+		if (ret < 0)
+			return ret;
+
+		/* Modulate Trailer Bit */
+		ret = ir_raw_gen_manchester(&e, max - (e - events),
+					    &ir_rc6_timings[1], 1, 0);
+		if (ret < 0)
+			return ret;
+
+		/* Modulate rest of the data */
+		ret = ir_raw_gen_manchester(&e, max - (e - events),
+					    &ir_rc6_timings[2],
+					    bits,
+					    scancode);
+		if (ret < 0)
+			return ret;
+	}
+
+	return e - events;
+}
+
+static struct ir_raw_handler rc6_handler = {
+	.protocols	= RC_PROTO_BIT_RC6_0 | RC_PROTO_BIT_RC6_6A_20 |
+			  RC_PROTO_BIT_RC6_6A_24 | RC_PROTO_BIT_RC6_6A_32 |
+			  RC_PROTO_BIT_RC6_MCE,
+	.decode		= ir_rc6_decode,
+	.encode		= ir_rc6_encode,
+	.carrier	= 36000,
+	.min_timeout	= RC6_SUFFIX_SPACE,
+};
+
+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");