1 files changed, 278 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..37b99432a
--- /dev/null
+++ b/drivers/media/rc/ir-nec-decoder.c
@@ -0,0 +1,278 @@
+// SPDX-License-Identifier: GPL-2.0
+// ir-nec-decoder.c - handle NEC IR Pulse/Space protocol
+//
+// Copyright (C) 2010 by Mauro Carvalho Chehab
+
+#include <linux/bitrev.h>
+#include <linux/module.h>
+#include "rc-core-priv.h"
+
+#define NEC_NBITS		32
+#define NEC_UNIT		563  /* us */
+#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
+ * @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_nec_decode(struct rc_dev *dev, struct ir_raw_event ev)
+{
+	struct nec_dec *data = &dev->raw->nec;
+	u32 scancode;
+	enum rc_proto rc_proto;
+	u8 address, not_address, command, not_command;
+
+	if (!is_timing_event(ev)) {
+		if (ev.overflow)
+			data->state = STATE_INACTIVE;
+		return 0;
+	}
+
+	dev_dbg(&dev->dev, "NEC decode started at state %d (%uus %s)\n",
+		data->state, 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)) {
+			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)) {
+			dev_dbg(&dev->dev, "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;
+
+		if (data->count == NEC_NBITS) {
+			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);
+
+			scancode = ir_nec_bytes_to_scancode(address,
+							    not_address,
+							    command,
+							    not_command,
+							    &rc_proto);
+
+			if (data->is_nec_x)
+				data->necx_repeat = true;
+
+			rc_keydown(dev, rc_proto, scancode, 0);
+		} else {
+			rc_repeat(dev);
+		}
+
+		data->state = STATE_INACTIVE;
+		return 0;
+	}
+
+	dev_dbg(&dev->dev, "NEC decode failed at count %d state %d (%uus %s)\n",
+		data->count, data->state, ev.duration, TO_STR(ev.pulse));
+	data->state = STATE_INACTIVE;
+	return -EINVAL;
+}
+
+/**
+ * ir_nec_scancode_to_raw() - encode an NEC scancode ready for modulation.
+ * @protocol:	specific protocol to use
+ * @scancode:	a single NEC scancode.
+ */
+static u32 ir_nec_scancode_to_raw(enum rc_proto protocol, u32 scancode)
+{
+	unsigned int addr, addr_inv, data, data_inv;
+
+	data = scancode & 0xff;
+
+	if (protocol == RC_PROTO_NEC32) {
+		/* 32-bit NEC (used by Apple and TiVo remotes) */
+		/* scan encoding: aaAAddDD */
+		addr_inv   = (scancode >> 24) & 0xff;
+		addr       = (scancode >> 16) & 0xff;
+		data_inv   = (scancode >>  8) & 0xff;
+	} else if (protocol == RC_PROTO_NECX) {
+		/* Extended NEC */
+		/* scan encoding AAaaDD */
+		addr       = (scancode >> 16) & 0xff;
+		addr_inv   = (scancode >>  8) & 0xff;
+		data_inv   = data ^ 0xff;
+	} else {
+		/* Normal NEC */
+		/* scan encoding: AADD */
+		addr       = (scancode >>  8) & 0xff;
+		addr_inv   = addr ^ 0xff;
+		data_inv   = data ^ 0xff;
+	}
+
+	/* raw encoding: ddDDaaAA */
+	return data_inv << 24 |
+	       data     << 16 |
+	       addr_inv <<  8 |
+	       addr;
+}
+
+static const struct ir_raw_timings_pd ir_nec_timings = {
+	.header_pulse	= NEC_HEADER_PULSE,
+	.header_space	= NEC_HEADER_SPACE,
+	.bit_pulse	= NEC_BIT_PULSE,
+	.bit_space[0]	= NEC_BIT_0_SPACE,
+	.bit_space[1]	= NEC_BIT_1_SPACE,
+	.trailer_pulse	= NEC_TRAILER_PULSE,
+	.trailer_space	= NEC_TRAILER_SPACE,
+	.msb_first	= 0,
+};
+
+/**
+ * ir_nec_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.
+ */
+static int ir_nec_encode(enum rc_proto protocol, u32 scancode,
+			 struct ir_raw_event *events, unsigned int max)
+{
+	struct ir_raw_event *e = events;
+	int ret;
+	u32 raw;
+
+	/* Convert a NEC scancode to raw NEC data */
+	raw = ir_nec_scancode_to_raw(protocol, scancode);
+
+	/* Modulate the raw data using a pulse distance modulation */
+	ret = ir_raw_gen_pd(&e, max, &ir_nec_timings, NEC_NBITS, raw);
+	if (ret < 0)
+		return ret;
+
+	return e - events;
+}
+
+static struct ir_raw_handler nec_handler = {
+	.protocols	= RC_PROTO_BIT_NEC | RC_PROTO_BIT_NECX |
+							RC_PROTO_BIT_NEC32,
+	.decode		= ir_nec_decode,
+	.encode		= ir_nec_encode,
+	.carrier	= 38000,
+	.min_timeout	= NEC_TRAILER_SPACE,
+};
+
+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 v2");
+MODULE_AUTHOR("Mauro Carvalho Chehab");
+MODULE_AUTHOR("Red Hat Inc. (http://www.redhat.com)");
+MODULE_DESCRIPTION("NEC IR protocol decoder");