1 files changed, 261 insertions, 0 deletions
diff --git a/drivers/input/touchscreen/ts_filter_median.c b/drivers/input/touchscreen/ts_filter_median.c
new file mode 100644
index 00000000000..6f8aae5941d
--- /dev/null
+++ b/drivers/input/touchscreen/ts_filter_median.c
@@ -0,0 +1,261 @@
+/*
+ * 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 program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ *
+ * Copyright (c) 2008 Andy Green <andy@warmcat.com>
+ *
+ *
+ * Median averaging stuff.  We sort incoming raw samples into an array of
+ * MEDIAN_SIZE length, discarding the oldest sample each time once we are full.
+ * We then return the sum of the middle three samples for X and Y.  It means
+ * the final result must be divided by (3 * scaling factor) to correct for
+ * avoiding the repeated /3.
+ *
+ * This strongly rejects brief excursions away from a central point that is
+ * sticky in time compared to the excursion duration.
+ *
+ * Thanks to Dale Schumacher (who wrote some example code) and Carl-Daniel
+ * Halifinger who pointed out this would be a good method.
+ */
+
+#include <linux/errno.h>
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include "ts_filter_median.h"
+
+struct ts_filter_median {
+	/* Private configuration. */
+	struct ts_filter_median_configuration *config;
+	/* Generic Filter API. */
+	struct ts_filter tsf;
+
+	/* Count raw samples we get. */
+	int samples_count;
+	/*
+	 * Remember the last coordinates we got in order to know if
+	 * we are moving slow or fast.
+	 */
+	int last_issued[MAX_TS_FILTER_COORDS];
+	/* How many samples in the sort buffer are valid. */
+	int valid;
+	/* Samples taken for median in sorted form. */
+	int *sort[MAX_TS_FILTER_COORDS];
+	/* Samples taken for median. */
+	int *fifo[MAX_TS_FILTER_COORDS];
+	/* Where we are in the fifo sample memory. */
+	int pos;
+	/* Do we have a sample to deliver? */
+	int ready;
+};
+
+#define ts_filter_to_filter_median(f) \
+	container_of(f, struct ts_filter_median, tsf)
+
+
+static void ts_filter_median_insert(int *p, int sample, int count)
+{
+	int n;
+
+	/* Search through what we got so far to find where to put sample. */
+	for (n = 0; n < count; n++)
+		if (sample < p[n]) {	/* We met somebody bigger than us? */
+			/* Starting from the end, push bigger guys down one. */
+			for (count--; count >= n; count--)
+				p[count + 1] = p[count];
+			p[n] = sample; /* Put us in place of first bigger. */
+			return;
+		}
+
+	p[count] = sample; /* Nobody was bigger than us, add us on the end. */
+}
+
+static void ts_filter_median_del(int *p, int value, int count)
+{
+	int index;
+
+	for (index = 0; index < count; index++)
+		if (p[index] == value) {
+			for (; index < count; index++)
+				p[index] = p[index + 1];
+			return;
+		}
+}
+
+
+static void ts_filter_median_clear(struct ts_filter *tsf)
+{
+	struct ts_filter_median *tsfm = ts_filter_to_filter_median(tsf);
+
+	tsfm->pos = 0;
+	tsfm->valid = 0;
+	tsfm->ready = 0;
+	memset(&tsfm->last_issued[0], 1, tsf->count_coords * sizeof(int));
+}
+
+static struct ts_filter *ts_filter_median_create(
+	struct platform_device *pdev,
+	const struct ts_filter_configuration *conf,
+	int count_coords)
+{
+	int *p;
+	int n;
+	struct ts_filter_median *tsfm = kzalloc(sizeof(struct ts_filter_median),
+								    GFP_KERNEL);
+
+	if (!tsfm)
+		return NULL;
+
+	tsfm->config = container_of(conf,
+				    struct ts_filter_median_configuration,
+				    config);
+
+	tsfm->tsf.count_coords = count_coords;
+
+	tsfm->config->midpoint = (tsfm->config->extent >> 1) + 1;
+
+	p = kmalloc(2 * count_coords * sizeof(int) * (tsfm->config->extent + 1),
+		    GFP_KERNEL);
+	if (!p) {
+		kfree(tsfm);
+		return NULL;
+	}
+
+	for (n = 0; n < count_coords; n++) {
+		tsfm->sort[n] = p;
+		p += tsfm->config->extent + 1;
+		tsfm->fifo[n] = p;
+		p += tsfm->config->extent + 1;
+	}
+
+	ts_filter_median_clear(&tsfm->tsf);
+
+	dev_info(&pdev->dev,
+		 "Created Median filter len:%d coords:%d dec_threshold:%d\n",
+		 tsfm->config->extent, count_coords,
+		 tsfm->config->decimation_threshold);
+
+	return &tsfm->tsf;
+}
+
+static void ts_filter_median_destroy(struct ts_filter *tsf)
+{
+	struct ts_filter_median *tsfm = ts_filter_to_filter_median(tsf);
+
+	kfree(tsfm->sort[0]); /* First guy has pointer from kmalloc. */
+	kfree(tsf);
+}
+
+static void ts_filter_median_scale(struct ts_filter *tsf, int *coords)
+{
+	int n;
+
+	for (n = 0; n < tsf->count_coords; n++)
+		coords[n] = (coords[n] + 2) / 3;
+}
+
+/*
+ * Give us the raw sample data coords, and if we return 1 then you can
+ * get a filtered coordinate from coords. If we return 0 you didn't
+ * fill all the filters with samples yet.
+ */
+
+static int ts_filter_median_process(struct ts_filter *tsf, int *coords)
+{
+	struct ts_filter_median *tsfm = ts_filter_to_filter_median(tsf);
+	int n;
+	int movement = 1;
+
+	for (n = 0; n < tsf->count_coords; n++) {
+		/* Grab copy in insertion order to remove when oldest. */
+		tsfm->fifo[n][tsfm->pos] = coords[n];
+		/* Insert these samples in sorted order in the median arrays. */
+		ts_filter_median_insert(tsfm->sort[n], coords[n], tsfm->valid);
+	}
+	/* Move us on in the fifo. */
+	if (++tsfm->pos == (tsfm->config->extent + 1))
+		tsfm->pos = 0;
+
+	/* Have we finished a median sampling? */
+	if (++tsfm->valid < tsfm->config->extent)
+		goto process_exit; /* No valid sample to use. */
+
+	BUG_ON(tsfm->valid != tsfm->config->extent);
+
+	tsfm->valid--;
+
+	/*
+	 * Sum the middle 3 in the median sorted arrays. We don't divide back
+	 * down which increases the sum resolution by a factor of 3 until the
+	 * scale API function is called.
+	 */
+	for (n = 0; n < tsf->count_coords; n++)
+		/* Perform the deletion of the oldest sample. */
+		ts_filter_median_del(tsfm->sort[n], tsfm->fifo[n][tsfm->pos],
+				     tsfm->valid);
+
+	tsfm->samples_count--;
+	if (tsfm->samples_count >= 0)
+		goto process_exit;
+
+	for (n = 0; n < tsf->count_coords; n++) {
+		/* Give the coordinate result from summing median 3. */
+		coords[n] = tsfm->sort[n][tsfm->config->midpoint - 1] +
+			    tsfm->sort[n][tsfm->config->midpoint] +
+			    tsfm->sort[n][tsfm->config->midpoint + 1];
+
+		movement += abs(tsfm->last_issued[n] - coords[n]);
+	}
+
+	if (movement > tsfm->config->decimation_threshold) /* Moving fast. */
+		tsfm->samples_count = tsfm->config->decimation_above;
+	else
+		tsfm->samples_count = tsfm->config->decimation_below;
+
+	memcpy(&tsfm->last_issued[0], coords, tsf->count_coords * sizeof(int));
+
+	tsfm->ready = 1;
+
+process_exit:
+	return 0;
+}
+
+static int ts_filter_median_haspoint(struct ts_filter *tsf)
+{
+	struct ts_filter_median *priv = ts_filter_to_filter_median(tsf);
+
+	return priv->ready;
+}
+
+static void ts_filter_median_getpoint(struct ts_filter *tsf, int *point)
+{
+	struct ts_filter_median *priv = ts_filter_to_filter_median(tsf);
+
+	BUG_ON(!priv->ready);
+
+	memcpy(point, &priv->last_issued[0], tsf->count_coords * sizeof(int));
+
+	priv->ready = 0;
+}
+
+const struct ts_filter_api ts_filter_median_api = {
+	.create =	ts_filter_median_create,
+	.destroy =	ts_filter_median_destroy,
+	.clear =	ts_filter_median_clear,
+	.process =	ts_filter_median_process,
+	.scale =	ts_filter_median_scale,
+	.haspoint =	ts_filter_median_haspoint,
+	.getpoint =	ts_filter_median_getpoint,
+};
+EXPORT_SYMBOL_GPL(ts_filter_median_api);
+