summaryrefslogtreecommitdiffstats
path: root/firmware/target/arm/imx233/touchscreen-imx233.c
blob: f98dc9b7387582f5fcfd5ce39ba520af23d9a537 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
/***************************************************************************
 *             __________               __   ___.
 *   Open      \______   \ ____   ____ |  | _\_ |__   _______  ___
 *   Source     |       _//  _ \_/ ___\|  |/ /| __ \ /  _ \  \/  /
 *   Jukebox    |    |   (  <_> )  \___|    < | \_\ (  <_> > <  <
 *   Firmware   |____|_  /\____/ \___  >__|_ \|___  /\____/__/\_ \
 *                     \/            \/     \/    \/            \/
 * $Id$
 *
 * Copyright (C) 2012 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.
 *
 ****************************************************************************/

#include "config.h"
#include "kernel.h"
#include "touchscreen-imx233.h"
#include "stdlib.h"
#ifdef SAMSUNG_YPZ5
#include "pinctrl-imx233.h"
#endif

/* 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 NR_SAMPLES  10
#define DELAY       1

static enum touch_state_t touch_state;
static int touch_chan = -1;
#if IMX233_SUBTARGET < 3700
/* See imx233_touchscreen_init() */
static int touch_chan_xp = -1, touch_chan_yp = -1;
#endif
static int touch_delay = -1;
static int touch_x, touch_y;
/* 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 process(void);

void INT_TOUCH_DETECT(void)
{
    process();
}

static void touch_channel_irq(int chan)
{
    imx233_icoll_enable_interrupt(INT_SRC_LRADC_CHx(chan), false);
    imx233_lradc_enable_channel_irq(chan, false);
    process();
}

#ifdef SAMSUNG_YPZ5
/* On this target we need to manually setup pulldown pins,
 * using specific GPIO lines
 */
static void pulldown_setup(bool xminus_enable, bool yminus_enable,
    bool xplus_enable, bool yplus_enable)
{
    /* TX+ */
    imx233_pinctrl_set_gpio(0, 25, xplus_enable);
    /* TX- */
    imx233_pinctrl_set_gpio(3, 15, xminus_enable);
    /* TY+ */
    imx233_pinctrl_set_gpio(0, 26, yplus_enable);
    /* TY- */
    imx233_pinctrl_set_gpio(1, 21, yminus_enable);
}
#endif

static void kick_measure(bool pull_x, bool pull_y, bool detect, int src)
{
#if IMX233_SUBTARGET < 3700
    /* Select proper channel on STMP3600 */
    if(src == LRADC_SRC_XPLUS)
        touch_chan = touch_chan_xp;
    else if(src == LRADC_SRC_XPLUS)
        touch_chan = touch_chan_xp;
    else
        panicf("Unknown channel source %d in touchscreen", src);
#endif
    /* enable interrupt */
    imx233_lradc_set_channel_irq_callback(touch_chan, &touch_channel_irq);
    imx233_icoll_enable_interrupt(INT_SRC_LRADC_CHx(touch_chan), true);
    imx233_lradc_enable_channel_irq(touch_chan, true);
    /* setup measurement: x- pull down and x+ pull up */
#ifdef SAMSUNG_YPZ5
    pulldown_setup(pull_x, pull_y, pull_x, pull_y);
#endif
    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_source(touch_chan, false, src);
    imx233_lradc_setup_sampling(touch_chan, true, NR_SAMPLES - 1);
    imx233_lradc_clear_channel(touch_chan);
    /* use a delay */
    imx233_lradc_setup_delay(touch_delay, 1 << touch_chan, 1 << touch_delay,
        NR_SAMPLES -1, DELAY);
    imx233_lradc_kick_delay(touch_delay);
}

static void enter_state(enum touch_state_t state)
{
    touch_state = state;
    switch(state)
    {
        case TOUCH_STATE_WAIT:
#ifdef SAMSUNG_YPZ5
            pulldown_setup(false, false, false, false);
#endif
            imx233_lradc_setup_touch(false, false, false, false, true);
            imx233_lradc_enable_touch_detect_irq(true);
            break;
        case TOUCH_STATE_MEASURE_X:
            kick_measure(true, false, false, LRADC_SRC_YPLUS);
            break;
        case TOUCH_STATE_MEASURE_Y:
            kick_measure(false, true, false, LRADC_SRC_XPLUS);
            break;
        case TOUCH_STATE_VERIFY:
            kick_measure(false, false, true, LRADC_SRC_YPLUS);
            break;
    }
}

static void process(void)
{
    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:
            touch_x = imx233_lradc_read_channel(touch_chan) / NR_SAMPLES;
            enter_state(TOUCH_STATE_MEASURE_Y);
            break;
        case TOUCH_STATE_MEASURE_Y:
                touch_y = imx233_lradc_read_channel(touch_chan) / NR_SAMPLES;
                enter_state(TOUCH_STATE_VERIFY);
            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 imx233_touchscreen_init(void)
{
    touch_delay = imx233_lradc_acquire_delay(TIMEOUT_NOBLOCK);
    if(touch_delay < 0)
        panicf("Cannot acquire delay for touchscreen measurement");
#if IMX233_SUBTARGET >= 3700
    /* On STMP3700+, any channel can measure any source so one channel is enough
     * for all operations */
    touch_chan = imx233_lradc_acquire_channel(LRADC_SRC_XPLUS, TIMEOUT_NOBLOCK);
    if(touch_chan < 0)
        panicf("touchscreen: cannot get adc channel");
#else
    /* On STMP3600, channel mapping is fixed for touch screen so we need to reserve
     * two channels */
    touch_chan_xp = imx233_lradc_acquire_channel(LRADC_SRC_XPLUS, TIMEOUT_NOBLOCK);
    if(touch_chan_xp < 0)
        panicf("touchscreen: cannot get adc X+ channel");
    touch_chan_yp = imx233_lradc_acquire_channel(LRADC_SRC_YPLUS, TIMEOUT_NOBLOCK);
    if(touch_chan_yp < 0)
        panicf("touchscreen: cannot get adc Y+ channel");
#endif
    imx233_touchscreen_enable(false);
}

void imx233_touchscreen_enable(bool enable)
{
    if(enable)
        enter_state(TOUCH_STATE_WAIT);
    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;
}