1 files changed, 267 insertions, 0 deletions
diff --git a/drivers/media/rc/ir-imon-decoder.c b/drivers/media/rc/ir-imon-decoder.c
new file mode 100644
index 000000000..dc68f64e7
--- /dev/null
+++ b/drivers/media/rc/ir-imon-decoder.c
@@ -0,0 +1,267 @@
+// SPDX-License-Identifier: GPL-2.0+
+// ir-imon-decoder.c - handle iMon protocol
+//
+// Copyright (C) 2018 by Sean Young <sean@mess.org>
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/module.h>
+#include "rc-core-priv.h"
+
+#define IMON_UNIT		416 /* us */
+#define IMON_BITS		30
+#define IMON_CHKBITS		(BIT(30) | BIT(25) | BIT(24) | BIT(22) | \
+				 BIT(21) | BIT(20) | BIT(19) | BIT(18) | \
+				 BIT(17) | BIT(16) | BIT(14) | BIT(13) | \
+				 BIT(12) | BIT(11) | BIT(10) | BIT(9))
+
+/*
+ * This protocol has 30 bits. The format is one IMON_UNIT header pulse,
+ * followed by 30 bits. Each bit is one IMON_UNIT check field, and then
+ * one IMON_UNIT field with the actual bit (1=space, 0=pulse).
+ * The check field is always space for some bits, for others it is pulse if
+ * both the preceding and current bit are zero, else space. IMON_CHKBITS
+ * defines which bits are of type check.
+ *
+ * There is no way to distinguish an incomplete message from one where
+ * the lower bits are all set, iow. the last pulse is for the lowest
+ * bit which is 0.
+ */
+enum imon_state {
+	STATE_INACTIVE,
+	STATE_BIT_CHK,
+	STATE_BIT_START,
+	STATE_FINISHED,
+	STATE_ERROR,
+};
+
+static void ir_imon_decode_scancode(struct rc_dev *dev)
+{
+	struct imon_dec *imon = &dev->raw->imon;
+
+	/* Keyboard/Mouse toggle */
+	if (imon->bits == 0x299115b7)
+		imon->stick_keyboard = !imon->stick_keyboard;
+
+	if ((imon->bits & 0xfc0000ff) == 0x680000b7) {
+		int rel_x, rel_y;
+		u8 buf;
+
+		buf = imon->bits >> 16;
+		rel_x = (buf & 0x08) | (buf & 0x10) >> 2 |
+			(buf & 0x20) >> 4 | (buf & 0x40) >> 6;
+		if (imon->bits & 0x02000000)
+			rel_x |= ~0x0f;
+		buf = imon->bits >> 8;
+		rel_y = (buf & 0x08) | (buf & 0x10) >> 2 |
+			(buf & 0x20) >> 4 | (buf & 0x40) >> 6;
+		if (imon->bits & 0x01000000)
+			rel_y |= ~0x0f;
+
+		if (rel_x && rel_y && imon->stick_keyboard) {
+			if (abs(rel_y) > abs(rel_x))
+				imon->bits = rel_y > 0 ?
+					0x289515b7 : /* KEY_DOWN */
+					0x2aa515b7;  /* KEY_UP */
+			else
+				imon->bits = rel_x > 0 ?
+					0x2ba515b7 : /* KEY_RIGHT */
+					0x29a515b7;  /* KEY_LEFT */
+		}
+
+		if (!imon->stick_keyboard) {
+			input_report_rel(dev->input_dev, REL_X, rel_x);
+			input_report_rel(dev->input_dev, REL_Y, rel_y);
+
+			input_report_key(dev->input_dev, BTN_LEFT,
+					 (imon->bits & 0x00010000) != 0);
+			input_report_key(dev->input_dev, BTN_RIGHT,
+					 (imon->bits & 0x00040000) != 0);
+		}
+	}
+
+	rc_keydown(dev, RC_PROTO_IMON, imon->bits, 0);
+}
+
+/**
+ * ir_imon_decode() - Decode one iMON 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_imon_decode(struct rc_dev *dev, struct ir_raw_event ev)
+{
+	struct imon_dec *data = &dev->raw->imon;
+
+	if (!is_timing_event(ev)) {
+		if (ev.overflow)
+			data->state = STATE_INACTIVE;
+		return 0;
+	}
+
+	dev_dbg(&dev->dev,
+		"iMON decode started at state %d bitno %d (%uus %s)\n",
+		data->state, data->count, ev.duration, TO_STR(ev.pulse));
+
+	/*
+	 * Since iMON protocol is a series of bits, if at any point
+	 * we encounter an error, make sure that any remaining bits
+	 * aren't parsed as a scancode made up of less bits.
+	 *
+	 * Note that if the stick is held, then the remote repeats
+	 * the scancode with about 12ms between them. So, make sure
+	 * we have at least 10ms of space after an error. That way,
+	 * we're at a new scancode.
+	 */
+	if (data->state == STATE_ERROR) {
+		if (!ev.pulse && ev.duration > MS_TO_US(10))
+			data->state = STATE_INACTIVE;
+		return 0;
+	}
+
+	for (;;) {
+		if (!geq_margin(ev.duration, IMON_UNIT, IMON_UNIT / 2))
+			return 0;
+
+		decrease_duration(&ev, IMON_UNIT);
+
+		switch (data->state) {
+		case STATE_INACTIVE:
+			if (ev.pulse) {
+				data->state = STATE_BIT_CHK;
+				data->bits = 0;
+				data->count = IMON_BITS;
+			}
+			break;
+		case STATE_BIT_CHK:
+			if (IMON_CHKBITS & BIT(data->count))
+				data->last_chk = ev.pulse;
+			else if (ev.pulse)
+				goto err_out;
+			data->state = STATE_BIT_START;
+			break;
+		case STATE_BIT_START:
+			data->bits <<= 1;
+			if (!ev.pulse)
+				data->bits |= 1;
+
+			if (IMON_CHKBITS & BIT(data->count)) {
+				if (data->last_chk != !(data->bits & 3))
+					goto err_out;
+			}
+
+			if (!data->count--)
+				data->state = STATE_FINISHED;
+			else
+				data->state = STATE_BIT_CHK;
+			break;
+		case STATE_FINISHED:
+			if (ev.pulse)
+				goto err_out;
+			ir_imon_decode_scancode(dev);
+			data->state = STATE_INACTIVE;
+			break;
+		}
+	}
+
+err_out:
+	dev_dbg(&dev->dev,
+		"iMON decode failed at state %d bitno %d (%uus %s)\n",
+		data->state, data->count, ev.duration, TO_STR(ev.pulse));
+
+	data->state = STATE_ERROR;
+
+	return -EINVAL;
+}
+
+/**
+ * ir_imon_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_imon_encode(enum rc_proto protocol, u32 scancode,
+			  struct ir_raw_event *events, unsigned int max)
+{
+	struct ir_raw_event *e = events;
+	int i, pulse;
+
+	if (!max--)
+		return -ENOBUFS;
+	init_ir_raw_event_duration(e, 1, IMON_UNIT);
+
+	for (i = IMON_BITS; i >= 0; i--) {
+		if (BIT(i) & IMON_CHKBITS)
+			pulse = !(scancode & (BIT(i) | BIT(i + 1)));
+		else
+			pulse = 0;
+
+		if (pulse == e->pulse) {
+			e->duration += IMON_UNIT;
+		} else {
+			if (!max--)
+				return -ENOBUFS;
+			init_ir_raw_event_duration(++e, pulse, IMON_UNIT);
+		}
+
+		pulse = !(scancode & BIT(i));
+
+		if (pulse == e->pulse) {
+			e->duration += IMON_UNIT;
+		} else {
+			if (!max--)
+				return -ENOBUFS;
+			init_ir_raw_event_duration(++e, pulse, IMON_UNIT);
+		}
+	}
+
+	if (e->pulse)
+		e++;
+
+	return e - events;
+}
+
+static int ir_imon_register(struct rc_dev *dev)
+{
+	struct imon_dec *imon = &dev->raw->imon;
+
+	imon->stick_keyboard = false;
+
+	return 0;
+}
+
+static struct ir_raw_handler imon_handler = {
+	.protocols	= RC_PROTO_BIT_IMON,
+	.decode		= ir_imon_decode,
+	.encode		= ir_imon_encode,
+	.carrier	= 38000,
+	.raw_register	= ir_imon_register,
+	.min_timeout	= IMON_UNIT * IMON_BITS * 2,
+};
+
+static int __init ir_imon_decode_init(void)
+{
+	ir_raw_handler_register(&imon_handler);
+
+	pr_info("IR iMON protocol handler initialized\n");
+	return 0;
+}
+
+static void __exit ir_imon_decode_exit(void)
+{
+	ir_raw_handler_unregister(&imon_handler);
+}
+
+module_init(ir_imon_decode_init);
+module_exit(ir_imon_decode_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Sean Young <sean@mess.org>");
+MODULE_DESCRIPTION("iMON IR protocol decoder");