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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
* - IMX233_BUTTON_LRADC_HOLD_DET: define hold detection method (ignored if !HAS_BUTTON_HOLD)
* - IMX233_BUTTON_LRADC_MODE: define the button lradc mode
*
* The LRADC code supports two modes of operations: VDDIO relative or absolute.
* In the (default) absolute value mode, the LRADC channel is sampled and its value
* is compared to the one in the imx233_button_lradc_mapping table. This is
* appropriate when the resistor ladder is derived from a fixed voltage.
* In the VDDIO relative mode, the values in imx233_button_lradc_mapping are
* the values for a specific value of VDDIO which is given by
* IMX233_BUTTON_LRADC_VDDIO. In this mode, the code will also sample VDDIO
* and do the following comparison:
* lradc_value <=? imx233_button_lradc_mapping[i] * vddio_ref / vddio_value
* where vddio_ref is IMX233_BUTTON_LRADC_VDDIO.
*
* The available values of IMX233_BUTTON_LRADC_HOLD are:
* - BLH_ADC: detect hold using adc
* - BLH_EXT: target button driver implements imx233_button_lradc_hold() using
* any external method of its choice
* - BLH_GPIO: detect hold using a GPIO, needs to define additional defines:
* + BLH_GPIO_BANK: pin bank
* + BLH_GPIO_PIN: pin in bank
* + BLH_GPIO_INVERTED: define if inverted, default is active high
* + BLH_GPIO_PULLUP: define if pins needs pullup
*
* WARNING
* There must always be entry in imx233_button_lradc_mapping whose value is the steady
* value of the channel when no button is pressed, and which maps to no button (.btn = 0)
*/
/* hold detect method */
#define BLH_ADC 0
#define BLH_EXT 1
#define BLH_GPIO 2
/* special value for btn to indicate end of list */
#define IMX233_BUTTON_LRADC_END -1
/* special value for btn to handle HOLD */
#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);
/* others gives the bitmask of other buttons: the function will OR the result
* with them except if hold is detected in which case 0 is always returned */
int imx233_button_lradc_read(int others);
#ifdef HAS_BUTTON_HOLD
bool imx233_button_lradc_hold(void);
#endif
int imx233_button_lradc_read_raw(void); // return raw adc value
#ifdef IMX233_BUTTON_LRADC_VDDIO
int imx233_button_lradc_read_vddio(void);
#endif
#endif /* __button_lradc_imx233__ */
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