V4L/DVB: ir-core: Add logic to decode IR protocols at the IR core

Adds a method to pass IR raw pulse/code events into ir-core. This is
needed in order to support LIRC. It also helps to move common code
from the drivers into the core.

In order to allow testing, it implements a simple NEC protocol decoder
at ir-nec-decoder.c file. The logic is about the same used at saa7134
driver that handles Avermedia M135A and Encore FM53 boards.

Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

1 files changed, 131 insertions, 0 deletions

diff --git a/drivers/media/IR/ir-nec-decoder.c b/drivers/media/IR/ir-nec-decoder.c
new file mode 100644
index 00000000000..16360eb4055
--- /dev/null
+++ b/drivers/media/IR/ir-nec-decoder.c
@@ -0,0 +1,131 @@
+/* ir-raw-event.c - handle IR Pulse/Space event
+ *
+ * Copyright (C) 2010 by Mauro Carvalho Chehab <mchehab@redhat.com>
+ *
+ * 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 <media/ir-core.h>
+
+/* Start time: 4.5 ms  */
+#define MIN_START_TIME	3900000
+#define MAX_START_TIME	5100000
+
+/* Pulse time: 560 us  */
+#define MIN_PULSE_TIME	460000
+#define MAX_PULSE_TIME	660000
+
+/* Bit 1 space time: 2.25ms-560 us */
+#define MIN_BIT1_TIME	1490000
+#define MAX_BIT1_TIME	1890000
+
+/* Bit 0 space time: 1.12ms-560 us */
+#define MIN_BIT0_TIME	360000
+#define MAX_BIT0_TIME	760000
+
+
+/** Decode NEC pulsecode. This code can take up to 76.5 ms to run.
+	Unfortunately, using IRQ to decode pulse didn't work, since it uses
+	a pulse train of 38KHz. This means one pulse on each 52 us
+*/
+
+int ir_nec_decode(struct input_dev *input_dev,
+		  struct ir_raw_event *evs,
+		  int len)
+{
+	int i, count = -1;
+	int ircode = 0, not_code = 0;
+#if 0
+	/* Needed only after porting the event code to the decoder */
+	struct ir_input_dev *ir = input_get_drvdata(input_dev);
+#endif
+
+	/* Be sure that the first event is an start one and is a pulse */
+	for (i = 0; i < len; i++) {
+		if (evs[i].type & (IR_START_EVENT | IR_PULSE))
+			break;
+	}
+	i++;	/* First event doesn't contain data */
+
+	if (i >= len)
+		return 0;
+
+	/* First space should have 4.5 ms otherwise is not NEC protocol */
+	if ((evs[i].delta.tv_nsec < MIN_START_TIME) |
+	    (evs[i].delta.tv_nsec > MAX_START_TIME) |
+	    (evs[i].type != IR_SPACE))
+		goto err;
+
+	/*
+	 * FIXME: need to implement the repeat sequence
+	 */
+
+	count = 0;
+	for (i++; i < len; i++) {
+		int bit;
+
+		if ((evs[i].delta.tv_nsec < MIN_PULSE_TIME) |
+		    (evs[i].delta.tv_nsec > MAX_PULSE_TIME) |
+		    (evs[i].type != IR_PULSE))
+			goto err;
+
+		if (++i >= len)
+			goto err;
+		if (evs[i].type != IR_SPACE)
+			goto err;
+
+		if ((evs[i].delta.tv_nsec > MIN_BIT1_TIME) &&
+		    (evs[i].delta.tv_nsec < MAX_BIT1_TIME))
+			bit = 1;
+		else if ((evs[i].delta.tv_nsec > MIN_BIT0_TIME) &&
+			 (evs[i].delta.tv_nsec < MAX_BIT0_TIME))
+			bit = 0;
+		else
+			goto err;
+
+		if (bit) {
+			int shift = count;
+			/* Address first, then command */
+			if (shift < 8) {
+				shift += 8;
+				ircode |= 1 << shift;
+			} else if (shift < 16) {
+				not_code |= 1 << shift;
+			} else if (shift < 24) {
+				shift -= 16;
+				ircode |= 1 << shift;
+			} else {
+				shift -= 24;
+				not_code |= 1 << shift;
+			}
+		}
+		if (++count == 32)
+			break;
+	}
+
+	/*
+	 * Fixme: may need to accept Extended NEC protocol?
+	 */
+	if ((ircode & ~not_code) != ircode) {
+		IR_dprintk(1, "NEC checksum error: code 0x%04x, not-code 0x%04x\n",
+			   ircode, not_code);
+		return -EINVAL;
+	}
+
+	IR_dprintk(1, "NEC scancode 0x%04x\n", ircode);
+
+	return ircode;
+err:
+	IR_dprintk(1, "NEC decoded failed at bit %d while decoding %luus time\n",
+		   count, (evs[i].delta.tv_nsec + 500) / 1000);
+
+	return -EINVAL;
+}
+EXPORT_SYMBOL_GPL(ir_nec_decode);