V4L/DVB: Add RC6 support to ir-core

This patch adds an RC6 decoder (modes 0 and 6A) to ir-core.

Signed-off-by: David Härdeman <david@hardeman.nu>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

1 files changed, 412 insertions, 0 deletions

diff --git a/drivers/media/IR/ir-rc6-decoder.c b/drivers/media/IR/ir-rc6-decoder.c
new file mode 100644
index 000000000000..ccc5be240f82
--- /dev/null
+++ b/drivers/media/IR/ir-rc6-decoder.c
@@ -0,0 +1,412 @@
+/* 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 "ir-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	PULSE(6)
+#define RC6_PREFIX_SPACE	SPACE(2)
+#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 */
+
+/* Used to register rc6_decoder clients */
+static LIST_HEAD(decoder_list);
+static DEFINE_SPINLOCK(decoder_lock);
+
+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,
+};
+
+struct decoder_data {
+	struct list_head	list;
+	struct ir_input_dev	*ir_dev;
+	int			enabled:1;
+
+	/* State machine control */
+	enum rc6_state		state;
+	u8			header;
+	u32			body;
+	int			last_unit;
+	bool			toggle;
+	unsigned		count;
+	unsigned		wanted_bits;
+};
+
+
+/**
+ * get_decoder_data()	- gets decoder data
+ * @input_dev:	input device
+ *
+ * Returns the struct decoder_data that corresponds to a device
+ */
+static struct decoder_data *get_decoder_data(struct  ir_input_dev *ir_dev)
+{
+	struct decoder_data *data = NULL;
+
+	spin_lock(&decoder_lock);
+	list_for_each_entry(data, &decoder_list, list) {
+		if (data->ir_dev == ir_dev)
+			break;
+	}
+	spin_unlock(&decoder_lock);
+	return data;
+}
+
+static ssize_t store_enabled(struct device *d,
+			     struct device_attribute *mattr,
+			     const char *buf,
+			     size_t len)
+{
+	unsigned long value;
+	struct ir_input_dev *ir_dev = dev_get_drvdata(d);
+	struct decoder_data *data = get_decoder_data(ir_dev);
+
+	if (!data)
+		return -EINVAL;
+
+	if (strict_strtoul(buf, 10, &value) || value > 1)
+		return -EINVAL;
+
+	data->enabled = value;
+
+	return len;
+}
+
+static ssize_t show_enabled(struct device *d,
+			     struct device_attribute *mattr, char *buf)
+{
+	struct ir_input_dev *ir_dev = dev_get_drvdata(d);
+	struct decoder_data *data = get_decoder_data(ir_dev);
+
+	if (!data)
+		return -EINVAL;
+
+	if (data->enabled)
+		return sprintf(buf, "1\n");
+	else
+	return sprintf(buf, "0\n");
+}
+
+static DEVICE_ATTR(enabled, S_IRUGO | S_IWUSR, show_enabled, store_enabled);
+
+static struct attribute *decoder_attributes[] = {
+	&dev_attr_enabled.attr,
+	NULL
+};
+
+static struct attribute_group decoder_attribute_group = {
+	.name	= "rc6_decoder",
+	.attrs	= decoder_attributes,
+};
+
+static enum rc6_mode rc6_mode(struct decoder_data *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
+ * @input_dev:	the struct input_dev descriptor of the device
+ * @duration:	duration of pulse/space in ns
+ *
+ * This function returns -EINVAL if the pulse violates the state machine
+ */
+static int ir_rc6_decode(struct input_dev *input_dev, s64 duration)
+{
+	struct decoder_data *data;
+	struct ir_input_dev *ir_dev = input_get_drvdata(input_dev);
+	u32 scancode;
+	u8 toggle;
+	int u;
+
+	data = get_decoder_data(ir_dev);
+	if (!data)
+		return -EINVAL;
+
+	if (!data->enabled)
+		return 0;
+
+	if (IS_RESET(duration)) {
+		data->state = STATE_INACTIVE;
+		return 0;
+	}
+
+	u =  TO_UNITS(duration, RC6_UNIT);
+	if (DURATION(u) == 0)
+		goto out;
+
+again:
+	IR_dprintk(2, "RC6 decode started at state %i (%i units, %ius)\n",
+		   data->state, u, TO_US(duration));
+
+	if (DURATION(u) == 0 && data->state != STATE_FINISHED)
+		return 0;
+
+	switch (data->state) {
+
+	case STATE_INACTIVE:
+		if (u >= RC6_PREFIX_PULSE - 1 && u <= RC6_PREFIX_PULSE + 1) {
+			data->state = STATE_PREFIX_SPACE;
+			data->count = 0;
+			return 0;
+		}
+		break;
+
+	case STATE_PREFIX_SPACE:
+		if (u == RC6_PREFIX_SPACE) {
+			data->state = STATE_HEADER_BIT_START;
+			return 0;
+		}
+		break;
+
+	case STATE_HEADER_BIT_START:
+		if (DURATION(u) == 1) {
+			data->header <<= 1;
+			if (IS_PULSE(u))
+				data->header |= 1;
+			data->count++;
+			data->last_unit = u;
+			data->state = STATE_HEADER_BIT_END;
+			return 0;
+		}
+		break;
+
+	case STATE_HEADER_BIT_END:
+		if (IS_TRANSITION(u, data->last_unit)) {
+			if (data->count == RC6_HEADER_NBITS)
+				data->state = STATE_TOGGLE_START;
+			else
+				data->state = STATE_HEADER_BIT_START;
+
+			DECREASE_DURATION(u, 1);
+			goto again;
+		}
+		break;
+
+	case STATE_TOGGLE_START:
+		if (DURATION(u) == 2) {
+			data->toggle = IS_PULSE(u);
+			data->last_unit = u;
+			data->state = STATE_TOGGLE_END;
+			return 0;
+		}
+		break;
+
+	case STATE_TOGGLE_END:
+		if (IS_TRANSITION(u, data->last_unit) && DURATION(u) >= 2) {
+			data->state = STATE_BODY_BIT_START;
+			data->last_unit = u;
+			DECREASE_DURATION(u, 2);
+			data->count = 0;
+
+			if (!(data->header & RC6_STARTBIT_MASK)) {
+				IR_dprintk(1, "RC6 invalid start bit\n");
+				break;
+			}
+
+			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 ((DURATION(u) == 0 && IS_SPACE(data->last_unit)) || DURATION(u) > 0)
+					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;
+		}
+		break;
+
+	case STATE_BODY_BIT_START:
+		if (DURATION(u) == 1) {
+			data->body <<= 1;
+			if (IS_PULSE(u))
+				data->body |= 1;
+			data->count++;
+			data->last_unit = u;
+
+			/*
+			 * If the last bit is one, a space will merge
+			 * with the silence after the command.
+			 */
+			if (IS_PULSE(u) && data->count == data->wanted_bits) {
+				data->state = STATE_FINISHED;
+				goto again;
+			}
+
+			data->state = STATE_BODY_BIT_END;
+			return 0;
+		}
+		break;
+
+	case STATE_BODY_BIT_END:
+		if (IS_TRANSITION(u, data->last_unit)) {
+			if (data->count == data->wanted_bits)
+				data->state = STATE_FINISHED;
+			else
+				data->state = STATE_BODY_BIT_START;
+
+			DECREASE_DURATION(u, 1);
+			goto again;
+		}
+		break;
+
+	case STATE_FINISHED:
+		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;
+		}
+
+		ir_keydown(input_dev, scancode, toggle);
+		data->state = STATE_INACTIVE;
+		return 0;
+	}
+
+out:
+	IR_dprintk(1, "RC6 decode failed at state %i (%i units, %ius)\n",
+		   data->state, u, TO_US(duration));
+	data->state = STATE_INACTIVE;
+	return -EINVAL;
+}
+
+static int ir_rc6_register(struct input_dev *input_dev)
+{
+	struct ir_input_dev *ir_dev = input_get_drvdata(input_dev);
+	struct decoder_data *data;
+	int rc;
+
+	rc = sysfs_create_group(&ir_dev->dev.kobj, &decoder_attribute_group);
+	if (rc < 0)
+		return rc;
+
+	data = kzalloc(sizeof(*data), GFP_KERNEL);
+	if (!data) {
+		sysfs_remove_group(&ir_dev->dev.kobj, &decoder_attribute_group);
+		return -ENOMEM;
+	}
+
+	data->ir_dev = ir_dev;
+	data->enabled = 1;
+
+	spin_lock(&decoder_lock);
+	list_add_tail(&data->list, &decoder_list);
+	spin_unlock(&decoder_lock);
+
+	return 0;
+}
+
+static int ir_rc6_unregister(struct input_dev *input_dev)
+{
+	struct ir_input_dev *ir_dev = input_get_drvdata(input_dev);
+	static struct decoder_data *data;
+
+	data = get_decoder_data(ir_dev);
+	if (!data)
+		return 0;
+
+	sysfs_remove_group(&ir_dev->dev.kobj, &decoder_attribute_group);
+
+	spin_lock(&decoder_lock);
+	list_del(&data->list);
+	spin_unlock(&decoder_lock);
+
+	return 0;
+}
+
+static struct ir_raw_handler rc6_handler = {
+	.decode		= ir_rc6_decode,
+	.raw_register	= ir_rc6_register,
+	.raw_unregister	= ir_rc6_unregister,
+};
+
+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");