V4L/DVB: Teach drivers/media/IR/ir-raw-event.c to use durations

drivers/media/IR/ir-raw-event.c is currently written with the assumption
that all "raw" hardware will generate events only on state change (i.e.
when a pulse or space starts).

However, some hardware (like mceusb, probably the most popular IR receiver
out there) only generates duration data (and that data is buffered so using
any kind of timing on the data is futile).

Furthermore, using signed int's to represent pulse/space durations is a
well-known approach when writing ir decoders.

With this patch:

- s64 int's are used to represent pulse/space durations in ns

- a workqueue is used to decode the ir protocols outside of interrupt context

- #defines are added to make decoders clearer

- decoder reset is implemented by passing a zero duration to the kfifo queue
  and decoders are updated accordingly

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

1 files changed, 75 insertions, 75 deletions

diff --git a/drivers/media/IR/ir-rc5-decoder.c b/drivers/media/IR/ir-rc5-decoder.c
index 6323066438b..1d0857b6908 100644
--- a/drivers/media/IR/ir-rc5-decoder.c
+++ b/drivers/media/IR/ir-rc5-decoder.c
@@ -21,11 +21,8 @@
 
 #include <media/ir-core.h>
 
-static unsigned int ir_rc5_remote_gap = 888888;
-
 #define RC5_NBITS		14
-#define RC5_BIT			(ir_rc5_remote_gap * 2)
-#define RC5_DURATION		(ir_rc5_remote_gap * RC5_NBITS)
+#define RC5_UNIT		888888 /* ns */
 
 /* Used to register rc5_decoder clients */
 static LIST_HEAD(decoder_list);
@@ -33,13 +30,9 @@ static DEFINE_SPINLOCK(decoder_lock);
 
 enum rc5_state {
 	STATE_INACTIVE,
-	STATE_MARKSPACE,
-	STATE_TRAILER,
-};
-
-struct rc5_code {
-	u8	address;
-	u8	command;
+	STATE_BIT_START,
+	STATE_BIT_END,
+	STATE_FINISHED,
 };
 
 struct decoder_data {
@@ -49,8 +42,9 @@ struct decoder_data {
 
 	/* State machine control */
 	enum rc5_state		state;
-	struct rc5_code		rc5_code;
-	unsigned		code, elapsed, last_bit, last_code;
+	u32			rc5_bits;
+	int			last_unit;
+	unsigned		count;
 };
 
 
@@ -122,18 +116,19 @@ static struct attribute_group decoder_attribute_group = {
 };
 
 /**
- * handle_event() - Decode one RC-5 pulse or space
+ * ir_rc5_decode() - Decode one RC-5 pulse or space
  * @input_dev:	the struct input_dev descriptor of the device
- * @ev:		event array with type/duration of pulse/space
+ * @duration:	duration of pulse/space in ns
  *
  * This function returns -EINVAL if the pulse violates the state machine
  */
-static int ir_rc5_decode(struct input_dev *input_dev,
-			struct ir_raw_event *ev)
+static int ir_rc5_decode(struct input_dev *input_dev, s64 duration)
 {
 	struct decoder_data *data;
 	struct ir_input_dev *ir_dev = input_get_drvdata(input_dev);
-	int is_pulse, scancode, delta, toggle;
+	u8 command, system, toggle;
+	u32 scancode;
+	int u;
 
 	data = get_decoder_data(ir_dev);
 	if (!data)
@@ -142,79 +137,84 @@ static int ir_rc5_decode(struct input_dev *input_dev,
 	if (!data->enabled)
 		return 0;
 
-	delta = DIV_ROUND_CLOSEST(ev->delta.tv_nsec, ir_rc5_remote_gap);
-
-	/* The duration time refers to the last bit time */
-	is_pulse = (ev->type & IR_PULSE) ? 1 : 0;
-
-	/* Very long delays are considered as start events */
-	if (delta > RC5_DURATION || (ev->type & IR_START_EVENT))
+	if (IS_RESET(duration)) {
 		data->state = STATE_INACTIVE;
-
-	switch (data->state) {
-	case STATE_INACTIVE:
-	IR_dprintk(2, "currently inative. Start bit (%s) @%uus\n",
-		   is_pulse ? "pulse" : "space",
-		   (unsigned)(ev->delta.tv_nsec + 500) / 1000);
-
-		/* Discards the initial start space */
-		if (!is_pulse)
-			goto err;
-		data->code = 1;
-		data->last_bit = 1;
-		data->elapsed = 0;
-		memset(&data->rc5_code, 0, sizeof(data->rc5_code));
-		data->state = STATE_MARKSPACE;
 		return 0;
-	case STATE_MARKSPACE:
-		if (delta != 1)
-			data->last_bit = data->last_bit ? 0 : 1;
+	}
 
-		data->elapsed += delta;
+	u = TO_UNITS(duration, RC5_UNIT);
+	if (DURATION(u) == 0)
+		goto out;
 
-		if ((data->elapsed % 2) == 1)
-			return 0;
+again:
+	IR_dprintk(2, "RC5 decode started at state %i (%i units, %ius)\n",
+		   data->state, u, TO_US(duration));
 
-		data->code <<= 1;
-		data->code |= data->last_bit;
-
-		/* Fill the 2 unused bits at the command with 0 */
-		if (data->elapsed / 2 == 6)
-			data->code <<= 2;
+	if (DURATION(u) == 0 && data->state != STATE_FINISHED)
+		return 0;
 
-		if (data->elapsed >= (RC5_NBITS - 1) * 2) {
-			scancode = data->code;
+	switch (data->state) {
 
-			/* Check for the start bits */
-			if ((scancode & 0xc000) != 0xc000) {
-				IR_dprintk(1, "Code 0x%04x doesn't have two start bits. It is not RC-5\n", scancode);
-				goto err;
+	case STATE_INACTIVE:
+		if (IS_PULSE(u)) {
+			data->state = STATE_BIT_START;
+			data->count = 1;
+			DECREASE_DURATION(u, 1);
+			goto again;
+		}
+		break;
+
+	case STATE_BIT_START:
+		if (DURATION(u) == 1) {
+			data->rc5_bits <<= 1;
+			if (IS_SPACE(u))
+				data->rc5_bits |= 1;
+			data->count++;
+			data->last_unit = u;
+
+			/*
+			 * If the last bit is zero, a space will merge
+			 * with the silence after the command.
+			 */
+			if (IS_PULSE(u) && data->count == RC5_NBITS) {
+				data->state = STATE_FINISHED;
+				goto again;
 			}
 
-			toggle = (scancode & 0x2000) ? 1 : 0;
+			data->state = STATE_BIT_END;
+			return 0;
+		}
+		break;
 
-			if (scancode == data->last_code) {
-				IR_dprintk(1, "RC-5 repeat\n");
-				ir_repeat(input_dev);
-			} else {
-				data->last_code = scancode;
-				scancode &= 0x1fff;
-				IR_dprintk(1, "RC-5 scancode 0x%04x\n", scancode);
+	case STATE_BIT_END:
+		if (IS_TRANSITION(u, data->last_unit)) {
+			if (data->count == RC5_NBITS)
+				data->state = STATE_FINISHED;
+			else
+				data->state = STATE_BIT_START;
 
-				ir_keydown(input_dev, scancode, 0);
-			}
-			data->state = STATE_TRAILER;
+			DECREASE_DURATION(u, 1);
+			goto again;
 		}
-		return 0;
-	case STATE_TRAILER:
+		break;
+
+	case STATE_FINISHED:
+		command  = (data->rc5_bits & 0x0003F) >> 0;
+		system   = (data->rc5_bits & 0x007C0) >> 6;
+		toggle   = (data->rc5_bits & 0x00800) ? 1 : 0;
+		command += (data->rc5_bits & 0x01000) ? 0 : 0x40;
+		scancode = system << 8 | command;
+
+		IR_dprintk(1, "RC5 scancode 0x%04x (toggle: %u)\n",
+			   scancode, toggle);
+		ir_keydown(input_dev, scancode, toggle);
 		data->state = STATE_INACTIVE;
 		return 0;
 	}
 
-err:
-	IR_dprintk(1, "RC-5 decoded failed at %s @ %luus\n",
-		   is_pulse ? "pulse" : "space",
-		   (ev->delta.tv_nsec + 500) / 1000);
+out:
+	IR_dprintk(1, "RC5 decode failed at state %i (%i units, %ius)\n",
+		   data->state, u, TO_US(duration));
 	data->state = STATE_INACTIVE;
 	return -EINVAL;
 }