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imx233: add generic lradc based button driver

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This driver does debouncing and best lradc usage and only requires
a sorted table of values to work, this factoring code as much as
possible.

Change-Id: I84b46f4b08094634e1c5deb5ca9ba20763389e66
This commit is contained in:
Amaury Pouly 2013-06-18 16:43:27 +02:00
parent 27aca8f276
commit 277d358eda
2 changed files with 178 additions and 0 deletions
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56
firmware/target/arm/imx233/button-lradc-imx233.h Normal file
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/***************************************************************************
* __________ __ ___.
* Open \______ \ ____ ____ | | _\_ |__ _______ ___
* Source | _// _ \_/ ___\| |/ /| __ \ / _ \ \/ /
* Jukebox | | ( <_> ) \___| < | \_\ ( <_> > < <
* Firmware |____|_ /\____/ \___ >__|_ \|___ /\____/__/\_ \
* \/ \/ \/ \/ \/
* $Id$
*
* Copyright (C) 2013 by Amaury Pouly
*
* 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; either version 2
* of the License, or (at your option) any later version.
*
* This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
* KIND, either express or implied.
*
****************************************************************************/
#ifndef __button_lradc_imx233__
#define __button_lradc_imx233__
#include "button.h"
#include "button-target.h"
/** This driver implements button sensing with lradc. It does debouncing
* and can handle hold sensing too. It can be tweaked using the following defines
* and variables:
* - imx233_button_lradc_mapping: target-defined table of adc values and mapping
* - IMX233_BUTTON_LRADC_CHANNEL: lradc channel to use
*/
/* special value for btn to handle HOLD */
#define IMX233_BUTTON_LRADC_END -1
#define IMX233_BUTTON_LRADC_HOLD -2
struct imx233_button_lradc_mapping_t
{
int adc_val;
int btn;
};
/* target-defined
* NOTE for proper operation, the table should contain entries for all states, including:
* - one with adc_val set to default value when no button is pressed
* - one with adc_val set to value when hold is selected (if hold is sensed using adc)
* - a dummy entry with btn set to IMX233_BUTTON_LRADC_END as the last entry
* The table must be sorted by increasing values of adc_val */
extern struct imx233_button_lradc_mapping_t imx233_button_lradc_mapping[];
void imx233_button_lradc_init(void);
int imx233_button_lradc_read(void);
bool imx233_button_lradc_hold(void);
#endif /* __button_lradc_imx233__ */