0324bf59a8
In most devices, the button ladder is not actually derived from VDDIO but from a constant voltage source, making it very easy to read it. However on some devices like ther ZEN X-Fi Style, the ladder is wired to VDDIO we can be changed so it's crucial that the button driver correctly scales the values wrt VDDIO. Change-Id: Ifc11abe2838fa7d16d0d60ecd96964a8dc5ea6d7
97 lines
4.1 KiB
C
97 lines
4.1 KiB
C
/***************************************************************************
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* __________ __ ___.
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* Open \______ \ ____ ____ | | _\_ |__ _______ ___
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* Source | _// _ \_/ ___\| |/ /| __ \ / _ \ \/ /
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* Jukebox | | ( <_> ) \___| < | \_\ ( <_> > < <
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* Firmware |____|_ /\____/ \___ >__|_ \|___ /\____/__/\_ \
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* \/ \/ \/ \/ \/
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* $Id$
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*
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* Copyright (C) 2013 by Amaury Pouly
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version 2
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* of the License, or (at your option) any later version.
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*
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* This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
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* KIND, either express or implied.
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*
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****************************************************************************/
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#ifndef __button_lradc_imx233__
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#define __button_lradc_imx233__
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#include "button.h"
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#include "button-target.h"
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/** This driver implements button sensing with lradc. It does debouncing
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* and can handle hold sensing too. It can be tweaked using the following defines
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* and variables:
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* - imx233_button_lradc_mapping: target-defined table of adc values and mapping
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* - IMX233_BUTTON_LRADC_CHANNEL: lradc channel to use
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* - IMX233_BUTTON_LRADC_HOLD_DET: define hold detection method (ignored if !HAS_BUTTON_HOLD)
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* - IMX233_BUTTON_LRADC_MODE: define the button lradc mode
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*
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* The LRADC code supports two modes of operations: VDDIO relative or absolute.
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* In the (default) absolute value mode, the LRADC channel is sampled and its value
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* is compared to the one in the imx233_button_lradc_mapping table. This is
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* appropriate when the resistor ladder is derived from a fixed voltage.
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* In the VDDIO relative mode, the values in imx233_button_lradc_mapping are
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* the values for a specific value of VDDIO which is given by
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* IMX233_BUTTON_LRADC_VDDIO. In this mode, the code will also sample VDDIO
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* and do the following comparison:
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* lradc_value <=? imx233_button_lradc_mapping[i] * vddio_ref / vddio_value
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* where vddio_ref is IMX233_BUTTON_LRADC_VDDIO.
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*
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* The available values of IMX233_BUTTON_LRADC_HOLD are:
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* - BLH_ADC: detect hold using adc
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* - BLH_EXT: target button driver implements imx233_button_lradc_hold() using
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* any external method of its choice
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* - BLH_GPIO: detect hold using a GPIO, needs to define additional defines:
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* + BLH_GPIO_BANK: pin bank
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* + BLH_GPIO_PIN: pin in bank
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* + BLH_GPIO_INVERTED: define if inverted, default is active high
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* + BLH_GPIO_PULLUP: define if pins needs pullup
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*
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* WARNING
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* There must always be entry in imx233_button_lradc_mapping whose value is the steady
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* value of the channel when no button is pressed, and which maps to no button (.btn = 0)
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*/
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/* hold detect method */
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#define BLH_ADC 0
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#define BLH_EXT 1
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#define BLH_GPIO 2
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/* special value for btn to indicate end of list */
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#define IMX233_BUTTON_LRADC_END -1
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/* special value for btn to handle HOLD */
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#define IMX233_BUTTON_LRADC_HOLD -2
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struct imx233_button_lradc_mapping_t
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{
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int adc_val;
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int btn;
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};
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/* target-defined
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* NOTE for proper operation, the table should contain entries for all states, including:
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* - one with adc_val set to default value when no button is pressed
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* - one with adc_val set to value when hold is selected (if hold is sensed using adc)
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* - a dummy entry with btn set to IMX233_BUTTON_LRADC_END as the last entry
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* The table must be sorted by increasing values of adc_val */
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extern struct imx233_button_lradc_mapping_t imx233_button_lradc_mapping[];
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void imx233_button_lradc_init(void);
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/* others gives the bitmask of other buttons: the function will OR the result
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* with them except if hold is detected in which case 0 is always returned */
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int imx233_button_lradc_read(int others);
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#ifdef HAS_BUTTON_HOLD
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bool imx233_button_lradc_hold(void);
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#endif
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int imx233_button_lradc_read_raw(void); // return raw adc value
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#ifdef IMX233_BUTTON_LRADC_VDDIO
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int imx233_button_lradc_read_vddio(void);
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#endif
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#endif /* __button_lradc_imx233__ */
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