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imx233: add touchscreen driver

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Change-Id: I406076d110e33cdae871222191d82262fabcf16a
This commit is contained in:
Amaury Pouly 2012-05-19 13:42:49 +02:00
parent 247e611f49
commit 85d5c19347
3 changed files with 230 additions and 0 deletions
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3
firmware/SOURCES
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@ -518,6 +518,9 @@ target/arm/imx233/lradc-imx233.c
target/arm/imx233/pwm-imx233.c
target/arm/imx233/rtc-imx233.c
target/arm/imx233/dcp-imx233.c
# ifdef HAVE_TOUCHSCREEN
target/arm/imx233/touchscreen-imx233.c
# endif
#ifndef BOOTLOADER
target/arm/imx233/debug-imx233.c
#endif

193
firmware/target/arm/imx233/touchscreen-imx233.c Normal file
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@ -0,0 +1,193 @@
/***************************************************************************
* __________ __ ___.
* Open \______ \ ____ ____ | | _\_ |__ _______ ___
* Source | _// _ \_/ ___\| |/ /| __ \ / _ \ \/ /
* Jukebox | | ( <_> ) \___| < | \_\ ( <_> > < <
* Firmware |____|_ /\____/ \___ >__|_ \|___ /\____/__/\_ \
* \/ \/ \/ \/ \/
* $Id$
*
* Copyright (C) 2012 by Amaury Pouly
*
* Based on Rockbox iriver bootloader by Linus Nielsen Feltzing
* and the ipodlinux bootloader by Daniel Palffy and Bernard Leach
*
* 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.
*
****************************************************************************/
#include "touchscreen-imx233.h"
#include "stdlib.h"
/* Description:
* the driver basically has 2 modes:
* - wait mode: use the hardware touch detect mechanism to wait for an edge
* - measurement mode: use pull up/down and adc to measure X/Y
* In measurement mode, we start by measuring X then Y then we check if
* the hardware still detect a touch. When no touch is detected anymore, we
* go back to wait mode.
* For each axis, we handle stabilization by repeatedly measuring the position
* until it is stable. We consider a set of measures stable when
* no measure is further away from the average than DEBOUNCE_THRESHOLD and
* we have at least SAMPLES_THRESHOLD measures. This avoids using magic
* timing constants specific to the touchscreen stabilization time and
* it is much more robust.
*
* Inspired by linux touchscreen driver for the stmp37xx.
*/
enum touch_state_t
{
TOUCH_STATE_WAIT, /* wait for touch */
TOUCH_STATE_MEASURE_X, /* measure x */
TOUCH_STATE_MEASURE_Y, /* measure y */
TOUCH_STATE_VERIFY, /* verify touch */
};
#define DEBOUNCE_THRESHOLD 100
#define SAMPLES_THRESHOLD 4
static enum touch_state_t touch_state;
static int touch_chan = -1;
static int touch_delay = -1;
static int touch_x, touch_y, nr_samples;
/* once a touch is confirmed, the parameters are copied to these value for
* instant readout by button code. */
static bool old_touch_detect = false;
static int old_touch_x, old_touch_y;
static void kick_measure(bool pull_x, bool pull_y, bool detect, int lradc_phys)
{
/* setup measurement: x- pull down and x+ pull up */
imx233_lradc_setup_touch(pull_x, pull_y, pull_x, pull_y, detect);
imx233_lradc_enable_touch_detect_irq(false);
imx233_lradc_enable_channel_irq(touch_chan, true);
/* measure channel, no accumulation */
imx233_lradc_setup_channel(touch_chan, false, false, 0, lradc_phys);
/* use a delay */
imx233_lradc_setup_delay(touch_delay, 1 << touch_chan, 0, 0, 8);
imx233_lradc_kick_delay(touch_delay);
}
static void enter_state(enum touch_state_t state)
{
touch_state = state;
switch(state)
{
case TOUCH_STATE_WAIT:
imx233_lradc_setup_touch(false, false, false, false, true);
imx233_lradc_enable_channel_irq(touch_chan, false);
imx233_lradc_enable_touch_detect_irq(true);
break;
case TOUCH_STATE_MEASURE_X:
kick_measure(true, false, false, HW_LRADC_CHANNEL_YPLUS);
break;
case TOUCH_STATE_MEASURE_Y:
kick_measure(false, true, false, HW_LRADC_CHANNEL_XPLUS);
break;
case TOUCH_STATE_VERIFY:
kick_measure(false, false, true, HW_LRADC_CHANNEL_YPLUS);
break;
}
}
static void process(void)
{
int val;
switch(touch_state)
{
case TOUCH_STATE_WAIT:
/* a touch has happened, check if it's still valid */
if(imx233_lradc_read_touch_detect())
enter_state(TOUCH_STATE_MEASURE_X);
else
{
old_touch_detect = false;
/* clear detect interrupt */
imx233_lradc_clear_touch_detect_irq();
}
break;
case TOUCH_STATE_MEASURE_X:
/* read value */
val = imx233_lradc_read_channel(touch_chan);
/* if value is too far from average, restart */
if(nr_samples > 0 && abs(val - touch_x) > DEBOUNCE_THRESHOLD)
nr_samples = 0;
touch_x = (touch_x * nr_samples + val) / (nr_samples + 1);
nr_samples++;
/* if we have enough samples, measure Y */
if(nr_samples > SAMPLES_THRESHOLD)
enter_state(TOUCH_STATE_MEASURE_Y);
else
imx233_lradc_kick_delay(touch_delay);
break;
case TOUCH_STATE_MEASURE_Y:
/* read value */
val = imx233_lradc_read_channel(touch_chan);
/* if value is too far from average, restart */
if(nr_samples > 0 && abs(val - touch_y) > DEBOUNCE_THRESHOLD)
nr_samples = 0;
touch_y = (touch_y * nr_samples + val) / (nr_samples + 1);
nr_samples++;
/* if we have enough samples, verify touch */
if(nr_samples > SAMPLES_THRESHOLD)
enter_state(TOUCH_STATE_VERIFY);
else
imx233_lradc_kick_delay(touch_delay);
break;
case TOUCH_STATE_VERIFY:
if(imx233_lradc_read_touch_detect())
{
old_touch_detect = true;
old_touch_x = touch_x;
old_touch_y = touch_y;
enter_state(TOUCH_STATE_MEASURE_X);
}
else
{
old_touch_detect = false;
enter_state(TOUCH_STATE_WAIT);
}
break;
}
}
void INT_TOUCH_DETECT(void)
{
process();
}
static void touch_channel_irq(int chan)
{
(void) chan;
process();
}
void imx233_touchscreen_init(void)
{
touch_chan = imx233_lradc_acquire_channel(TIMEOUT_NOBLOCK);
touch_delay = imx233_lradc_acquire_delay(TIMEOUT_NOBLOCK);
if(touch_chan < 0 || touch_delay < 0)
panicf("Cannot acquire channel and delays for touchscreen measurement");
imx233_touchscreen_enable(false);
}
void imx233_touchscreen_enable(bool enable)
{
enter_state(TOUCH_STATE_WAIT);
imx233_lradc_set_channel_irq_callback(touch_chan, &touch_channel_irq);
imx233_icoll_enable_interrupt(INT_SRC_LRADC_CHx(touch_chan), enable);
imx233_icoll_enable_interrupt(INT_SRC_TOUCH_DETECT, enable);
}
bool imx233_touchscreen_get_touch(int *raw_x, int *raw_y)
{
if(raw_x) *raw_x = old_touch_x;
if(raw_y) *raw_y = old_touch_y;
return old_touch_detect;
}

34
firmware/target/arm/imx233/touchscreen-imx233.h Normal file
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@ -0,0 +1,34 @@
/***************************************************************************
* __________ __ ___.
* Open \______ \ ____ ____ | | _\_ |__ _______ ___
* Source | _// _ \_/ ___\| |/ /| __ \ / _ \ \/ /
* Jukebox | | ( <_> ) \___| < | \_\ ( <_> > < <
* Firmware |____|_ /\____/ \___ >__|_ \|___ /\____/__/\_ \
* \/ \/ \/ \/ \/
* $Id$
*
* Copyright (C) 2012 by Amaury Pouly
*
* Based on Rockbox iriver bootloader by Linus Nielsen Feltzing
* and the ipodlinux bootloader by Daniel Palffy and Bernard Leach
*
* 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 __TOUCHSCREEN_IMX233__
#define __TOUCHSCREEN_IMX233__
#include "lradc-imx233.h"
void imx233_touchscreen_init(void);
void imx233_touchscreen_enable(bool enable);
/* returns true if there is a touch */
bool imx233_touchscreen_get_touch(int *raw_x, int *raw_y);
#endif /* __TOUCHSCREEN_IMX233__ */