imx233: rework touchscreen driver

The old driver didn't behave nicely because it waiting for
stability which could never arrive on some gestures. The new one
uses a fixed delay and averaging.

Change-Id: I8ff80f373b6792e6d5fc3cfe41b709642e61c38b

1 files changed, 37 insertions, 47 deletions

diff --git a/firmware/target/arm/imx233/touchscreen-imx233.c b/firmware/target/arm/imx233/touchscreen-imx233.c
index e76d7a49e3..c4d2f4d726 100644
--- a/firmware/target/arm/imx233/touchscreen-imx233.c
+++ b/firmware/target/arm/imx233/touchscreen-imx233.c
@@ -46,28 +46,53 @@ enum touch_state_t
     TOUCH_STATE_VERIFY, /* verify touch */
 };
 
-#define DEBOUNCE_THRESHOLD  100
-#define SAMPLES_THRESHOLD   4
+#define NR_SAMPLES  10
+#define DELAY       1
 
 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;
+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 kick_measure(bool pull_x, bool pull_y, bool detect, int lradc_phys)
+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();
+}
+
+static void kick_measure(bool pull_x, bool pull_y, bool detect, int src)
+{
+    if(touch_chan >= 0)
+        imx233_lradc_release_channel(touch_chan);
+    touch_chan = imx233_lradc_acquire_channel(src, TIMEOUT_NOBLOCK);
+    if(touch_chan < 0)
+        panicf("touchscreen: cannot get adc channel");
+    /* 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 */
     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);
+    imx233_lradc_setup_channel(touch_chan, false, true, NR_SAMPLES - 1, src);
+    imx233_lradc_clear_channel(touch_chan);
     /* use a delay */
-    imx233_lradc_setup_delay(touch_delay, 1 << touch_chan, 0, 0, 8);
+    imx233_lradc_setup_delay(touch_delay, 1 << touch_chan, 1 << touch_delay,
+        NR_SAMPLES -1, DELAY);
     imx233_lradc_kick_delay(touch_delay);
 }
 
@@ -78,7 +103,6 @@ static void enter_state(enum touch_state_t 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:
@@ -95,7 +119,6 @@ static void enter_state(enum touch_state_t state)
 
 static void process(void)
 {
-    int val;
     switch(touch_state)
     {
         case TOUCH_STATE_WAIT:
@@ -110,32 +133,12 @@ static void process(void)
             }
             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);
+            touch_x = imx233_lradc_read_channel(touch_chan) / NR_SAMPLES;
+            enter_state(TOUCH_STATE_MEASURE_Y);
             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)
+                touch_y = imx233_lradc_read_channel(touch_chan) / NR_SAMPLES;
                 enter_state(TOUCH_STATE_VERIFY);
-            else
-                imx233_lradc_kick_delay(touch_delay);
             break;
         case TOUCH_STATE_VERIFY:
             if(imx233_lradc_read_touch_detect())
@@ -154,31 +157,18 @@ static void process(void)
     }
 }
 
-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(LRADC_SRC_XPLUS, TIMEOUT_NOBLOCK);
     touch_delay = imx233_lradc_acquire_delay(TIMEOUT_NOBLOCK);
-    if(touch_chan < 0 || touch_delay < 0)
+    if(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);
+    if(enable)
+        enter_state(TOUCH_STATE_WAIT);
     imx233_icoll_enable_interrupt(INT_SRC_TOUCH_DETECT, enable);
 }