V4L/DVB (8625): saa7134: Add NEC prococol IR decoding capability

This patch adds the capability of decoding NEC protocol, received via GPIO18 line.
This GPIO port can trigger saa7134 IRQ.

A future improvement would be to make it a little more generic to work also
with GPIO16 line.

A pure IRQ code didn't work, since some delays were introduced on the tests we
did.

A possible approach would be to use polling at a rate of 2.5 ms or less. If a
new code were taken, a code similar to nec_task() could be used. However, this
would add an extra overhead to kernel, and will consume more power.

Due to that, we took an hybrid approach: an IRQ upper half to trigger when a
new key is received and a bottom half to convert pulse-distance into a keycode.

The bottom half is polling based, to improve performance. During the bottom
half proccess, GPIO18 IRQ line is disabled, preventing IRQ reentrancy and
improving performance a little bit.

Thanks to Sistema Fenix (http://www.sistemafenix.com.br/) for sponsoring this
development.
Signed-off-by: Gilberto <gilberto@sistemafenix.com.br>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

drivers/media/video/saa7134/saa7134-input.c

@@ -62,8 +62,11 @@ MODULE_PARM_DESC(disable_other_ir, "disable full codes of "
 #define i2cdprintk(fmt, arg...)    if (ir_debug) \
 	printk(KERN_DEBUG "%s/ir: " fmt, ir->c.name , ## arg)
 
-/** rc5 functions */
+/* Helper functions for RC5 and NEC decoding at GPIO16 or GPIO18 */
 static int saa7134_rc5_irq(struct saa7134_dev *dev);
+static int saa7134_nec_irq(struct saa7134_dev *dev);
+static void nec_task(unsigned long data);
+static void saa7134_nec_timer(unsigned long data);
 
 /* -------------------- GPIO generic keycode builder -------------------- */
 
@@ -280,7 +283,9 @@ void saa7134_input_irq(struct saa7134_dev *dev)
 {
 	struct card_ir *ir = dev->remote;
 
-	if (!ir->polling && !ir->rc5_gpio) {
+	if (ir->nec_gpio) {
+		saa7134_nec_irq(dev);
+	} else if (!ir->polling && !ir->rc5_gpio) {
 		build_key(dev);
 	} else if (ir->rc5_gpio) {
 		saa7134_rc5_irq(dev);
@@ -316,6 +321,10 @@ void saa7134_ir_start(struct saa7134_dev *dev, struct card_ir *ir)
 		ir->addr = 0x17;
 		ir->rc5_key_timeout = ir_rc5_key_timeout;
 		ir->rc5_remote_gap = ir_rc5_remote_gap;
+	} else if (ir->nec_gpio) {
+		setup_timer(&ir->timer_keyup, saa7134_nec_timer,
+			    (unsigned long)dev);
+		tasklet_init(&ir->tlet, nec_task, (unsigned long)dev);
 	}
 }
 
@@ -335,6 +344,7 @@ int saa7134_input_init1(struct saa7134_dev *dev)
 	u32 mask_keyup   = 0;
 	int polling      = 0;
 	int rc5_gpio	 = 0;
+	int nec_gpio	 = 0;
 	int ir_type      = IR_TYPE_OTHER;
 	int err;
 
@@ -533,6 +543,7 @@ int saa7134_input_init1(struct saa7134_dev *dev)
 	ir->mask_keyup   = mask_keyup;
 	ir->polling      = polling;
 	ir->rc5_gpio	 = rc5_gpio;
+	ir->nec_gpio	 = nec_gpio;
 
 	/* init input device */
 	snprintf(ir->name, sizeof(ir->name), "saa7134 IR (%s)",
@@ -675,8 +686,125 @@ static int saa7134_rc5_irq(struct saa7134_dev *dev)
 	return 1;
 }
 
-/* ----------------------------------------------------------------------
- * Local variables:
- * c-basic-offset: 8
- * End:
+
+/* On NEC protocol, One has 2.25 ms, and zero has 1.125 ms
+   The first pulse (start) has 9 + 4.5 ms
  */
+
+static void saa7134_nec_timer(unsigned long data)
+{
+	struct saa7134_dev *dev = (struct saa7134_dev *) data;
+	struct card_ir *ir = dev->remote;
+
+	dprintk("Cancel key repeat\n");
+
+	ir_input_nokey(ir->dev, &ir->ir);
+}
+
+static void nec_task(unsigned long data)
+{
+	struct saa7134_dev *dev = (struct saa7134_dev *) data;
+	struct card_ir *ir;
+	struct timeval tv;
+	int count, pulse, oldpulse, gap;
+	u32 ircode = 0, not_code = 0;
+	int ngap = 0;
+
+	if (!data) {
+		printk(KERN_ERR "saa713x/ir: Can't recover dev struct\n");
+		/* GPIO will be kept disabled */
+		return;
+	}
+
+	ir = dev->remote;
+
+	/* rising SAA7134_GPIO_GPRESCAN reads the status */
+	saa_clearb(SAA7134_GPIO_GPMODE3, SAA7134_GPIO_GPRESCAN);
+	saa_setb(SAA7134_GPIO_GPMODE3, SAA7134_GPIO_GPRESCAN);
+
+	oldpulse = saa_readl(SAA7134_GPIO_GPSTATUS0 >> 2) & ir->mask_keydown;
+	pulse = oldpulse;
+
+	do_gettimeofday(&tv);
+	ir->base_time = tv;
+
+	/* 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
+	 */
+	do {
+		/* Wait until the end of pulse/space or 5 ms */
+		for (count = 0; count < 500; count++)  {
+			udelay(10);
+			/* rising SAA7134_GPIO_GPRESCAN reads the status */
+			saa_clearb(SAA7134_GPIO_GPMODE3, SAA7134_GPIO_GPRESCAN);
+			saa_setb(SAA7134_GPIO_GPMODE3, SAA7134_GPIO_GPRESCAN);
+			pulse = saa_readl(SAA7134_GPIO_GPSTATUS0 >> 2)
+				& ir->mask_keydown;
+			if (pulse != oldpulse)
+				break;
+		}
+
+		do_gettimeofday(&tv);
+		gap = 1000000 * (tv.tv_sec - ir->base_time.tv_sec) +
+				tv.tv_usec - ir->base_time.tv_usec;
+
+		if (!pulse) {
+			/* Bit 0 has 560 us, while bit 1 has 1120 us.
+			   Do something only if bit == 1
+			 */
+			if (ngap && (gap > 560 + 280)) {
+				unsigned int shift = ngap - 1;
+
+				/* 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;
+				}
+			}
+			ngap++;
+		}
+
+
+		ir->base_time = tv;
+
+		/* TIMEOUT - Long pulse */
+		if (gap >= 5000)
+			break;
+		oldpulse = pulse;
+	} while (ngap < 32);
+
+	if (ngap == 32) {
+		/* FIXME: should check if not_code == ~ircode */
+		ir->code = ir_extract_bits(ircode, ir->mask_keycode);
+
+		dprintk("scancode = 0x%02x (code = 0x%02x, notcode= 0x%02x)\n",
+			 ir->code, ircode, not_code);
+
+		ir_input_keydown(ir->dev, &ir->ir, ir->code, ir->code);
+	} else
+		dprintk("Repeat last key\n");
+
+	/* Keep repeating the last key */
+	mod_timer(&ir->timer_keyup, jiffies + msecs_to_jiffies(150));
+
+	saa_setl(SAA7134_IRQ2, SAA7134_IRQ2_INTE_GPIO18);
+}
+
+static int saa7134_nec_irq(struct saa7134_dev *dev)
+{
+	struct card_ir *ir = dev->remote;
+
+	saa_clearl(SAA7134_IRQ2, SAA7134_IRQ2_INTE_GPIO18);
+	tasklet_schedule(&ir->tlet);
+
+	return 1;
+}

include/media/ir-common.h

@@ -25,6 +25,7 @@
 
 #include <linux/input.h>
 #include <linux/workqueue.h>
+#include <linux/interrupt.h>
 
 #define IR_TYPE_RC5     1
 #define IR_TYPE_PD      2 /* Pulse distance encoded IR */
@@ -85,6 +86,10 @@ struct card_ir {
 	u32 code;			/* raw code under construction */
 	struct timeval base_time;	/* time of last seen code */
 	int active;			/* building raw code */
+
+	/* NEC decoding */
+	u32			nec_gpio;
+	struct tasklet_struct   tlet;
 };
 
 void ir_input_init(struct input_dev *dev, struct ir_input_state *ir,