Commit 9b09df51 authored by Mauro Carvalho Chehab's avatar Mauro Carvalho Chehab
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V4L/DVB: ir-rc5-decoder: fix state machine 



Reimplement the RC-5 decoder state machine. Code is now clear, and works
properly. It is also simpler than the previous implementations.

Signed-off-by: default avatarMauro Carvalho Chehab <mchehab@redhat.com>
parent 7f20d32d

drivers/media/IR/ir-rc5-decoder.c

+52 −109
Original line number Diff line number Diff line
@@ -15,19 +15,17 @@ 
/*

 * This code only handles 14 bits RC-5 protocols. There are other variants

 * that use a different number of bits. This is currently unsupported

 * It considers a carrier of 36 kHz, with a total of 14 bits, where

 * the first two bits are start bits, and a third one is a filing bit

 */



#include <media/ir-core.h>



#define RC5_NBITS		14

#define RC5_HALFBIT		888888 /* ns */

#define RC5_BIT			(RC5_HALFBIT * 2)

#define RC5_DURATION		(RC5_BIT * RC5_NBITS)



#define is_rc5_halfbit(nsec) ((ev->delta.tv_nsec >= RC5_HALFBIT / 2) &&	   \

		      (ev->delta.tv_nsec < RC5_HALFBIT + RC5_HALFBIT / 2))

static unsigned int ir_rc5_remote_gap = 888888;



#define n_half(nsec) ((ev->delta.tv_nsec + RC5_HALFBIT / 2) / RC5_HALFBIT)

#define RC5_NBITS		14

#define RC5_BIT			(ir_rc5_remote_gap * 2)

#define RC5_DURATION		(ir_rc5_remote_gap * RC5_NBITS)



/* Used to register rc5_decoder clients */

static LIST_HEAD(decoder_list);
@@ -35,19 +33,8 @@ static spinlock_t decoder_lock; 


enum rc5_state {

	STATE_INACTIVE,

	STATE_START2_SPACE,

	STATE_START2_MARK,

	STATE_MARKSPACE,

	STATE_TRAILER_MARK,

};



static char *st_name[] = {

	"Inactive",

	"start2 sapce",

	"start2 mark",

	"mark",

	"space",

	"trailer"

	STATE_TRAILER,

};



struct rc5_code {
@@ -63,8 +50,7 @@ struct decoder_data { 
	/* State machine control */

	enum rc5_state		state;

	struct rc5_code		rc5_code;

	unsigned		n_half;

	unsigned		count;

	unsigned		code, elapsed, last_bit, last_code;

};
@@ -147,7 +133,7 @@ static int ir_rc5_decode(struct input_dev *input_dev, 
{

	struct decoder_data *data;

	struct ir_input_dev *ir_dev = input_get_drvdata(input_dev);

	int bit, last_bit, n_half;

	int is_pulse, scancode, delta, toggle;



	data = get_decoder_data(ir_dev);

	if (!data)
@@ -156,122 +142,79 @@ static int ir_rc5_decode(struct input_dev *input_dev, 
	if (!data->enabled)

		return 0;



	/* Except for the initial event, what matters is the previous bit */

	bit = (ev->type & IR_PULSE) ? 1 : 0;

	delta = DIV_ROUND_CLOSEST(ev->delta.tv_nsec, ir_rc5_remote_gap);



	last_bit = !bit;



	/* Discards spurious space last_bits when inactive */

	/* 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 (ev->delta.tv_nsec > RC5_DURATION + RC5_HALFBIT / 2)

		data->state = STATE_INACTIVE;



	if (ev->type & IR_START_EVENT)

	if (delta > RC5_DURATION || (ev->type & IR_START_EVENT))

		data->state = STATE_INACTIVE;



	switch (data->state) {

	case STATE_INACTIVE:

IR_dprintk(1, "currently inative. Received bit (%s) @%luus\n",

	last_bit ? "pulse" : "space",

	(ev->delta.tv_nsec + 500) / 1000);

	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 (bit)

			return 0;

		data->count = 0;

		data->n_half = 0;

		memset (&data->rc5_code, 0, sizeof(data->rc5_code));



		data->state = STATE_START2_SPACE;

		return 0;

	case STATE_START2_SPACE:

		if (last_bit)

			goto err;

		if (!is_rc5_halfbit(ev->delta.tv_nsec))

			goto err;

		data->state = STATE_START2_MARK;

		return 0;

	case STATE_START2_MARK:

		if (!last_bit)

			goto err;



		if (!is_rc5_halfbit(ev->delta.tv_nsec))

		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:

		n_half = n_half(ev->delta.tv_nsec);

		if (n_half < 1 || n_half > 3) {

			IR_dprintk(1, "Decode failed at %d-th bit (%s) @%luus\n",

				data->count,

				last_bit ? "pulse" : "space",

				(ev->delta.tv_nsec + 500) / 1000);

printk("%d halves\n", n_half);

			goto err2;

		}

		data->n_half += n_half;

		if (delta != 1)

			data->last_bit = data->last_bit ? 0 : 1;



		if (!last_bit)

			return 0;

		data->elapsed += delta;



		/* Got one complete mark/space cycle */

		if ((data->elapsed % 2) == 1)

			return 0;



		bit = ((data->count + 1) * 2)/ data->n_half;

		data->code <<= 1;

		data->code |= data->last_bit;



printk("%d halves, %d bits\n", n_half, bit);

		/* Fill the 2 unused bits at the command with 0 */

		if (data->elapsed / 2 == 6)

			data->code <<= 2;



#if 1 /* SANITY check - while testing the decoder */

		if (bit > 1) {

			IR_dprintk(1, "Decoder HAS failed at %d-th bit (%s) @%luus\n",

				data->count,

				last_bit ? "pulse" : "space",

				(ev->delta.tv_nsec + 500) / 1000);

		if (data->elapsed >= (RC5_NBITS - 1) * 2) {

			scancode = data->code;



			goto err2;

			/* 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;

			}

#endif

		/* Ok, we've got a valid bit. proccess it */

		if (bit) {

			int shift = data->count;



			/*

			 * RC-5 transmit bytes on this temporal order:

			 * address | not address | command | not command

			 */

			if (shift < 8) {

				data->rc5_code.address |= 1 << shift;

			toggle = (scancode & 0x2000) ? 1 : 0;



			if (scancode == data->last_code) {

				IR_dprintk(1, "RC-5 repeat\n");

				ir_repeat(input_dev);

			} else {

				data->rc5_code.command |= 1 << (shift - 8);

			}

		}

		IR_dprintk(1, "RC-5: bit #%d: %d (%d)\n",

				data->count, bit, data->n_half);

		if (++data->count >= RC5_NBITS) {

			u32 scancode;

			scancode = data->rc5_code.address << 8 |

					data->rc5_code.command;

				data->last_code = scancode;

				scancode &= 0x1fff;

				IR_dprintk(1, "RC-5 scancode 0x%04x\n", scancode);



				ir_keydown(input_dev, scancode, 0);



			data->state = STATE_TRAILER_MARK;

			}

			data->state = STATE_TRAILER;

		}

		return 0;

	case STATE_TRAILER_MARK:

		if (!last_bit)

			goto err;

	case STATE_TRAILER:

		data->state = STATE_INACTIVE;

		return 0;

	}



err:

	IR_dprintk(1, "RC-5 decoded failed at state %s (%s) @ %luus\n",

		   st_name[data->state],

		   bit ? "pulse" : "space",

	IR_dprintk(1, "RC-5 decoded failed at %s @ %luus\n",

		   is_pulse ? "pulse" : "space",

		   (ev->delta.tv_nsec + 500) / 1000);

err2:

	data->state = STATE_INACTIVE;

	return -EINVAL;

}