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, 86 insertions, 57 deletions

diff --git a/drivers/media/IR/ir-raw-event.c b/drivers/media/IR/ir-raw-event.c
index bc4ca08adf4a..e144f1522962 100644
--- a/drivers/media/IR/ir-raw-event.c
+++ b/drivers/media/IR/ir-raw-event.c
@@ -15,9 +15,10 @@
 #include <media/ir-core.h>
 #include <linux/workqueue.h>
 #include <linux/spinlock.h>
+#include <linux/sched.h>
 
-/* Define the max number of bit transitions per IR keycode */
-#define MAX_IR_EVENT_SIZE	256
+/* Define the max number of pulse/space transitions to buffer */
+#define MAX_IR_EVENT_SIZE      512
 
 /* Used to handle IR raw handler extensions */
 static LIST_HEAD(ir_raw_handler_list);
@@ -53,19 +54,30 @@ static DEFINE_SPINLOCK(ir_raw_handler_lock);
 /* Used to load the decoders */
 static struct work_struct wq_load;
 
+static void ir_raw_event_work(struct work_struct *work)
+{
+	s64 d;
+	struct ir_raw_event_ctrl *raw =
+		container_of(work, struct ir_raw_event_ctrl, rx_work);
+
+	while (kfifo_out(&raw->kfifo, &d, sizeof(d)) == sizeof(d))
+		RUN_DECODER(decode, raw->input_dev, d);
+}
+
 int ir_raw_event_register(struct input_dev *input_dev)
 {
 	struct ir_input_dev *ir = input_get_drvdata(input_dev);
-	int rc, size;
+	int rc;
 
 	ir->raw = kzalloc(sizeof(*ir->raw), GFP_KERNEL);
 	if (!ir->raw)
 		return -ENOMEM;
 
-	size = sizeof(struct ir_raw_event) * MAX_IR_EVENT_SIZE * 2;
-	size = roundup_pow_of_two(size);
+	ir->raw->input_dev = input_dev;
+	INIT_WORK(&ir->raw->rx_work, ir_raw_event_work);
 
-	rc = kfifo_alloc(&ir->raw->kfifo, size, GFP_KERNEL);
+	rc = kfifo_alloc(&ir->raw->kfifo, sizeof(s64) * MAX_IR_EVENT_SIZE,
+			 GFP_KERNEL);
 	if (rc < 0) {
 		kfree(ir->raw);
 		ir->raw = NULL;
@@ -90,6 +102,7 @@ void ir_raw_event_unregister(struct input_dev *input_dev)
 	if (!ir->raw)
 		return;
 
+	cancel_work_sync(&ir->raw->rx_work);
 	RUN_DECODER(raw_unregister, input_dev);
 
 	kfifo_free(&ir->raw->kfifo);
@@ -97,74 +110,90 @@ void ir_raw_event_unregister(struct input_dev *input_dev)
 	ir->raw = NULL;
 }
 
-int ir_raw_event_store(struct input_dev *input_dev, enum raw_event_type type)
+/**
+ * ir_raw_event_store() - pass a pulse/space duration to the raw ir decoders
+ * @input_dev:	the struct input_dev device descriptor
+ * @duration:	duration of the pulse or space in ns
+ *
+ * This routine (which may be called from an interrupt context) stores a
+ * pulse/space duration for the raw ir decoding state machines. Pulses are
+ * signalled as positive values and spaces as negative values. A zero value
+ * will reset the decoding state machines.
+ */
+int ir_raw_event_store(struct input_dev *input_dev, s64 duration)
 {
-	struct ir_input_dev	*ir = input_get_drvdata(input_dev);
-	struct timespec		ts;
-	struct ir_raw_event	event;
-	int			rc;
+	struct ir_input_dev *ir = input_get_drvdata(input_dev);
 
 	if (!ir->raw)
 		return -EINVAL;
 
-	event.type = type;
-	event.delta.tv_sec = 0;
-	event.delta.tv_nsec = 0;
+	if (kfifo_in(&ir->raw->kfifo, &duration, sizeof(duration)) != sizeof(duration))
+		return -ENOMEM;
 
-	ktime_get_ts(&ts);
+	return 0;
+}
+EXPORT_SYMBOL_GPL(ir_raw_event_store);
 
-	if (timespec_equal(&ir->raw->last_event, &event.delta))
-		event.type |= IR_START_EVENT;
-	else
-		event.delta = timespec_sub(ts, ir->raw->last_event);
+/**
+ * ir_raw_event_store_edge() - notify raw ir decoders of the start of a pulse/space
+ * @input_dev:	the struct input_dev device descriptor
+ * @type:	the type of the event that has occurred
+ *
+ * This routine (which may be called from an interrupt context) is used to
+ * store the beginning of an ir pulse or space (or the start/end of ir
+ * reception) for the raw ir decoding state machines. This is used by
+ * hardware which does not provide durations directly but only interrupts
+ * (or similar events) on state change.
+ */
+int ir_raw_event_store_edge(struct input_dev *input_dev, enum raw_event_type type)
+{
+	struct ir_input_dev	*ir = input_get_drvdata(input_dev);
+	ktime_t			now;
+	s64			delta; /* ns */
+	int			rc = 0;
 
-	memcpy(&ir->raw->last_event, &ts, sizeof(ts));
+	if (!ir->raw)
+		return -EINVAL;
 
-	if (event.delta.tv_sec) {
-		event.type |= IR_START_EVENT;
-		event.delta.tv_sec = 0;
-		event.delta.tv_nsec = 0;
-	}
+	now = ktime_get();
+	delta = ktime_to_ns(ktime_sub(now, ir->raw->last_event));
 
-	kfifo_in(&ir->raw->kfifo, &event, sizeof(event));
+	/* Check for a long duration since last event or if we're
+	 * being called for the first time, note that delta can't
+	 * possibly be negative.
+	 */
+	if (delta > NSEC_PER_SEC || !ir->raw->last_type)
+		type |= IR_START_EVENT;
+
+	if (type & IR_START_EVENT)
+		ir_raw_event_reset(input_dev);
+	else if (ir->raw->last_type & IR_SPACE)
+		rc = ir_raw_event_store(input_dev, -delta);
+	else if (ir->raw->last_type & IR_PULSE)
+		rc = ir_raw_event_store(input_dev, delta);
+	else
+		return 0;
 
+	ir->raw->last_event = now;
+	ir->raw->last_type = type;
 	return rc;
 }
-EXPORT_SYMBOL_GPL(ir_raw_event_store);
+EXPORT_SYMBOL_GPL(ir_raw_event_store_edge);
 
-int ir_raw_event_handle(struct input_dev *input_dev)
+/**
+ * ir_raw_event_handle() - schedules the decoding of stored ir data
+ * @input_dev:	the struct input_dev device descriptor
+ *
+ * This routine will signal the workqueue to start decoding stored ir data.
+ */
+void ir_raw_event_handle(struct input_dev *input_dev)
 {
-	struct ir_input_dev		*ir = input_get_drvdata(input_dev);
-	int				rc;
-	struct ir_raw_event		ev;
-	int 				len, i;
-
-	/*
-	 * Store the events into a temporary buffer. This allows calling more than
-	 * one decoder to deal with the received data
-	 */
-	len = kfifo_len(&ir->raw->kfifo) / sizeof(ev);
-	if (!len)
-		return 0;
-
-	for (i = 0; i < len; i++) {
-		rc = kfifo_out(&ir->raw->kfifo, &ev, sizeof(ev));
-		if (rc != sizeof(ev)) {
-			IR_dprintk(1, "overflow error: received %d instead of %zd\n",
-				   rc, sizeof(ev));
-			return -EINVAL;
-		}
-		IR_dprintk(2, "event type %d, time before event: %07luus\n",
-			ev.type, (ev.delta.tv_nsec + 500) / 1000);
-		rc = RUN_DECODER(decode, input_dev, &ev);
-	}
+	struct ir_input_dev *ir = input_get_drvdata(input_dev);
 
-	/*
-	 * Call all ir decoders. This allows decoding the same event with
-	 * more than one protocol handler.
-	 */
+	if (!ir->raw)
+		return;
 
-	return rc;
+	schedule_work(&ir->raw->rx_work);
 }
 EXPORT_SYMBOL_GPL(ir_raw_event_handle);