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imx233: add generic lradc based button driver
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
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27aca8f276
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277d358eda
2 changed files with 178 additions and 0 deletions
122
firmware/target/arm/imx233/button-lradc-imx233.c
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122
firmware/target/arm/imx233/button-lradc-imx233.c
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/***************************************************************************
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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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#include "button-lradc-imx233.h"
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#include "stdlib.h"
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#include "lradc-imx233.h"
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#ifndef IMX233_BUTTON_LRADC_CHANNEL
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#error You must define IMX233_BUTTON_LRADC_CHANNEL to use button-lradc
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#endif
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/* physical channel */
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#define CHAN IMX233_BUTTON_LRADC_CHANNEL
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/* number of irq per second */
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#ifdef IMX233_BUTTON_LRADC_RATE
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# define RATE IMX233_BUTTON_LRADC_RATE
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#else
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# define RATE HZ
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#endif
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/* number of samples per irq */
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#ifdef IMX233_BUTTON_LRADC_SAMPLES
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# define SAMPLES IMX233_BUTTON_LRADC_SAMPLES
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#else
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# define SAMPLES 10
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#endif
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/* delay's delay */
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#define DELAY (LRADC_DELAY_FREQ / RATE / SAMPLES)
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static int button_delay;
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static int button_chan;
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static int button_val[2];
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static int button_idx;
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static int button_mask;
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static int table_size;
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static int button_find(int val)
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{
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// shortcuts
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struct imx233_button_lradc_mapping_t *table = imx233_button_lradc_mapping;
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/* FIXME use a dichotomy */
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int i = 0;
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while(i < table_size && val >= table[i].adc_val)
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i++;
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// extreme cases
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int btn = 0;
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// if i=n then choose i-1 and otherwise choose best between i-1 and i
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if(i == 0)
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btn = table[0].btn;
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else if(i == table_size)
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btn = table[i - 1].btn;
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// choose best between i-1 and i (note that table[i-1]<=val<=table[i]) */
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else if(val - table[i - 1].adc_val < table[i].adc_val - val)
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btn = table[i - 1].btn;
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else
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btn = table[i].btn;
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return btn;
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}
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int button_value;
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static void button_lradc_irq(int chan)
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{
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(void) chan;
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/* read value, kick channel */
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button_val[button_idx] = imx233_lradc_read_channel(button_chan) / SAMPLES;
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imx233_lradc_clear_channel(button_chan);
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imx233_lradc_setup_channel(button_chan, true, true, SAMPLES - 1, LRADC_SRC(CHAN));
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imx233_lradc_setup_delay(button_delay, 1 << button_chan, 0, SAMPLES - 1, DELAY);
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imx233_lradc_kick_delay(button_delay);
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button_value = button_val[button_idx];
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/* compute mask, compare to previous one */
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button_val[button_idx] = button_find(button_val[button_idx]);
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button_idx = 1 - button_idx;
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if(button_val[0] == button_val[1])
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button_mask = button_val[0];
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}
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void imx233_button_lradc_init(void)
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{
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button_chan = imx233_lradc_acquire_channel(LRADC_SRC(CHAN), TIMEOUT_NOBLOCK);
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if(button_chan < 0)
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panicf("Cannot get channel for button-lradc");
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button_delay = imx233_lradc_acquire_delay(TIMEOUT_NOBLOCK);
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if(button_delay < 0)
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panicf("Cannot get delay for button-lradc");
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imx233_lradc_setup_channel(button_chan, true, true, SAMPLES - 1, LRADC_SRC(CHAN));
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imx233_lradc_setup_delay(button_delay, 1 << button_chan, 0, SAMPLES - 1, DELAY);
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imx233_lradc_enable_channel_irq(button_chan, true);
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imx233_lradc_set_channel_irq_callback(button_chan, button_lradc_irq);
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imx233_lradc_kick_delay(button_delay);
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table_size = 0;
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while(imx233_button_lradc_mapping[table_size].btn != IMX233_BUTTON_LRADC_END)
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table_size++;
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}
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bool imx233_button_lradc_hold(void)
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{
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return button_mask == IMX233_BUTTON_LRADC_HOLD;
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}
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int imx233_button_lradc_read(void)
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{
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return button_mask == IMX233_BUTTON_LRADC_HOLD ? 0 : button_mask;
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}
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56
firmware/target/arm/imx233/button-lradc-imx233.h
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56
firmware/target/arm/imx233/button-lradc-imx233.h
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@ -0,0 +1,56 @@
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/***************************************************************************
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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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*/
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/* special value for btn to handle HOLD */
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#define IMX233_BUTTON_LRADC_END -1
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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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int imx233_button_lradc_read(void);
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bool imx233_button_lradc_hold(void);
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#endif /* __button_lradc_imx233__ */
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