/* ir-sharp-decoder.c - handle Sharp IR Pulse/Space protocol * * Copyright (C) 2013-2014 Imagination Technologies Ltd. * * Based on NEC decoder: * Copyright (C) 2010 by Mauro Carvalho Chehab * * 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 <linux/bitrev.h>#include <linux/module.h>#include "rc-core-priv.h" #define SHARP_NBITS		15#define SHARP_UNIT		40000  /* ns */#define SHARP_BIT_PULSE		(8    * SHARP_UNIT) /* 320us */#define SHARP_BIT_0_PERIOD	(25   * SHARP_UNIT) /* 1ms (680us space) */#define SHARP_BIT_1_PERIOD	(50   * SHARP_UNIT) /* 2ms (1680ms space) */#define SHARP_ECHO_SPACE	(1000 * SHARP_UNIT) /* 40 ms */#define SHARP_TRAILER_SPACE	(125  * SHARP_UNIT) /* 5 ms (even longer) */ enum sharp_state {	STATE_INACTIVE,	STATE_BIT_PULSE,	STATE_BIT_SPACE,	STATE_TRAILER_PULSE,	STATE_ECHO_SPACE,	STATE_TRAILER_SPACE,}; /** * ir_sharp_decode() - Decode one Sharp pulse or space * @dev:	the struct rc_dev descriptor of the device * @duration:	the struct ir_raw_event descriptor of the pulse/space * * This function returns -EINVAL if the pulse violates the state machine */static int ir_sharp_decode(struct rc_dev *dev, struct ir_raw_event ev){	struct sharp_dec *data = &dev->raw->sharp;	u32 msg, echo, address, command, scancode; 	if (!(dev->enabled_protocols & RC_BIT_SHARP))		return 0; 	if (!is_timing_event(ev)) {		if (ev.reset)			data->state = STATE_INACTIVE;		return 0;	} 	IR_dprintk(2, "Sharp decode started at state %d (%uus %s)\n",		   data->state, TO_US(ev.duration), TO_STR(ev.pulse)); 	switch (data->state) { 	case STATE_INACTIVE:		if (!ev.pulse)			break; 		if (!eq_margin(ev.duration, SHARP_BIT_PULSE,			       SHARP_BIT_PULSE / 2))			break; 		data->count = 0;		data->pulse_len = ev.duration;		data->state = STATE_BIT_SPACE;		return 0; 	case STATE_BIT_PULSE:		if (!ev.pulse)			break; 		if (!eq_margin(ev.duration, SHARP_BIT_PULSE,			       SHARP_BIT_PULSE / 2))			break; 		data->pulse_len = ev.duration;		data->state = STATE_BIT_SPACE;		return 0; 	case STATE_BIT_SPACE:		if (ev.pulse)			break; 		data->bits <<= 1;		if (eq_margin(data->pulse_len + ev.duration, SHARP_BIT_1_PERIOD,			      SHARP_BIT_PULSE * 2))			data->bits |= 1;		else if (!eq_margin(data->pulse_len + ev.duration,				    SHARP_BIT_0_PERIOD, SHARP_BIT_PULSE * 2))			break;		data->count++; 		if (data->count == SHARP_NBITS ||		    data->count == SHARP_NBITS * 2)			data->state = STATE_TRAILER_PULSE;		else			data->state = STATE_BIT_PULSE; 		return 0; 	case STATE_TRAILER_PULSE:		if (!ev.pulse)			break; 		if (!eq_margin(ev.duration, SHARP_BIT_PULSE,			       SHARP_BIT_PULSE / 2))			break; 		if (data->count == SHARP_NBITS) {			/* exp,chk bits should be 1,0 */			if ((data->bits & 0x3) != 0x2)				break;			data->state = STATE_ECHO_SPACE;		} else {			data->state = STATE_TRAILER_SPACE;		}		return 0; 	case STATE_ECHO_SPACE:		if (ev.pulse)			break; 		if (!eq_margin(ev.duration, SHARP_ECHO_SPACE,			       SHARP_ECHO_SPACE / 4))			break; 		data->state = STATE_BIT_PULSE; 		return 0; 	case STATE_TRAILER_SPACE:		if (ev.pulse)			break; 		if (!geq_margin(ev.duration, SHARP_TRAILER_SPACE,				SHARP_BIT_PULSE / 2))			break; 		/* Validate - command, ext, chk should be inverted in 2nd */		msg = (data->bits >> 15) & 0x7fff;		echo = data->bits & 0x7fff;		if ((msg ^ echo) != 0x3ff) {			IR_dprintk(1,				   "Sharp checksum error: received 0x%04x, 0x%04x\n",				   msg, echo);			break;		} 		address = bitrev8((msg >> 7) & 0xf8);		command = bitrev8((msg >> 2) & 0xff); 		scancode = address << 8 | command;		IR_dprintk(1, "Sharp scancode 0x%04x\n", scancode); 		rc_keydown(dev, RC_TYPE_SHARP, scancode, 0);		data->state = STATE_INACTIVE;		return 0;	} 	IR_dprintk(1, "Sharp decode failed at count %d state %d (%uus %s)\n",		   data->count, data->state, TO_US(ev.duration),		   TO_STR(ev.pulse));	data->state = STATE_INACTIVE;	return -EINVAL;} static struct ir_raw_handler sharp_handler = {	.protocols	= RC_BIT_SHARP,	.decode		= ir_sharp_decode,}; static int __init ir_sharp_decode_init(void){	ir_raw_handler_register(&sharp_handler); 	pr_info("IR Sharp protocol handler initialized\n");	return 0;} static void __exit ir_sharp_decode_exit(void){	ir_raw_handler_unregister(&sharp_handler);} module_init(ir_sharp_decode_init);module_exit(ir_sharp_decode_exit); MODULE_LICENSE("GPL");MODULE_AUTHOR("James Hogan <james.hogan@imgtec.com>");MODULE_DESCRIPTION("Sharp IR protocol decoder");