From: Nelson Castillo <arhuaco@xxxxxxxxxxxxxxxxx>
This filter is useful to reject samples that are not reliable.
We consider that a sample is not reliable if it deviates from the Majority.
Signed-off-by: Nelson Castillo <arhuaco@xxxxxxxxxxxxxxxxx>
---
drivers/input/touchscreen/Kconfig | 12 +
drivers/input/touchscreen/Makefile | 1
drivers/input/touchscreen/ts_filter_group.c | 221 +++++++++++++++++++++++++++
include/linux/ts_filter_group.h | 39 +++++
4 files changed, 273 insertions(+), 0 deletions(-)
create mode 100644 drivers/input/touchscreen/ts_filter_group.c
create mode 100644 include/linux/ts_filter_group.h
diff --git a/drivers/input/touchscreen/Kconfig b/drivers/input/touchscreen/Kconfig
index aed3eb0..09f55dd 100644
--- a/drivers/input/touchscreen/Kconfig
+++ b/drivers/input/touchscreen/Kconfig
@@ -19,6 +19,18 @@ menuconfig TOUCHSCREEN_FILTER
can be combined in any order in your machine init and the parameters
for them can also be set there.
+if TOUCHSCREEN_FILTER
+
+config TOUCHSCREEN_FILTER_GROUP
+ bool "Group Touchscreen Filter"
+ depends on INPUT_TOUCHSCREEN && TOUCHSCREEN_FILTER
+ default Y
+ help
+ Say Y here if you want to use the Group touchscreen filter, it
+ avoids using atypical samples.
+
+endif
+
config TOUCHSCREEN_ADS7846
tristate "ADS7846/TSC2046 and ADS7843 based touchscreens"
depends on SPI_MASTER
diff --git a/drivers/input/touchscreen/Makefile b/drivers/input/touchscreen/Makefile
index 74ab26f..9ccb21a 100644
--- a/drivers/input/touchscreen/Makefile
+++ b/drivers/input/touchscreen/Makefile
@@ -32,3 +32,4 @@ wm97xx-ts-$(CONFIG_TOUCHSCREEN_WM9712) += wm9712.o
wm97xx-ts-$(CONFIG_TOUCHSCREEN_WM9713) += wm9713.o
obj-$(CONFIG_TOUCHSCREEN_WM97XX_MAINSTONE) += mainstone-wm97xx.o
obj-$(CONFIG_TOUCHSCREEN_FILTER) += ts_filter.o
+obj-$(CONFIG_TOUCHSCREEN_FILTER_GROUP) += ts_filter_group.o
diff --git a/drivers/input/touchscreen/ts_filter_group.c b/drivers/input/touchscreen/ts_filter_group.c
new file mode 100644
index 0000000..73e3625
--- /dev/null
+++ b/drivers/input/touchscreen/ts_filter_group.c
@@ -0,0 +1,221 @@
+/*
+ * 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 by Openmoko, Inc.
+ * Author: Nelson Castillo <arhuaco@xxxxxxxxxxxxxxxxx>
+ * All rights reserved.
+ *
+ * This filter is useful to reject samples that are not reliable. We consider
+ * that a sample is not reliable if it deviates form the Majority.
+ *
+ * 1) We collect S samples.
+ *
+ * 2) For each dimension:
+ *
+ * - We sort the points.
+ * - Points that are "close enough" are considered to be in the same set.
+ * - We choose the set with more elements. If more than "threshold"
+ * points are in this set we use the first and the last point of the set
+ * to define the valid range for this dimension [min, max], otherwise we
+ * discard all the points and go to step 1.
+ *
+ * 3) We consider the unsorted S samples and try to feed them to the next
+ * filter in the chain. If one of the points of each sample
+ * is not in the allowed range for its dimension, we discard the sample.
+ *
+ */
+
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/sort.h>
+#include <linux/ts_filter_group.h>
+
+static void ts_filter_group_clear_internal(struct ts_filter_group *tsfg,
+ int attempts)
+{
+ tsfg->N = 0;
+ tsfg->tries_left = attempts;
+}
+
+static void ts_filter_group_clear(struct ts_filter *tsf)
+{
+ struct ts_filter_group *tsfg = (struct ts_filter_group *)tsf;
+
+ ts_filter_group_clear_internal(tsfg, tsfg->config->attempts);
+
+ if (tsf->next) /* chain */
+ (tsf->next->api->clear)(tsf->next);
+}
+
+static struct ts_filter *ts_filter_group_create(struct platform_device *pdev,
+ void *conf, int count_coords)
+{
+ struct ts_filter_group *tsfg;
+ int i;
+
+ BUG_ON((count_coords < 1) || (count_coords > MAX_TS_FILTER_COORDS));
+
+ tsfg = kzalloc(sizeof(struct ts_filter_group), GFP_KERNEL);
+ if (!tsfg)
+ return NULL;
+
+ tsfg->config = (struct ts_filter_group_configuration *)conf;
+ tsfg->tsf.count_coords = count_coords;
+
+ BUG_ON(tsfg->config->attempts <= 0);
+
+ tsfg->samples[0] = kmalloc((2 + count_coords) * sizeof(int) *
+ tsfg->config->extent, GFP_KERNEL);
+ if (!tsfg->samples[0]) {
+ kfree(tsfg);
+ return NULL;
+ }
+ for (i = 1; i < count_coords; ++i)
+ tsfg->samples[i] = tsfg->samples[0] + i * tsfg->config->extent;
+ tsfg->sorted_samples = tsfg->samples[0] + count_coords *
+ tsfg->config->extent;
+ tsfg->group_size = tsfg->samples[0] + (1 + count_coords) *
+ tsfg->config->extent;
+
+ ts_filter_group_clear_internal(tsfg, tsfg->config->attempts);
+
+ printk(KERN_INFO" Created group ts filter len %d depth %d close %d "
+ "thresh %d\n", tsfg->config->extent, count_coords,
+ tsfg->config->close_enough, tsfg->config->threshold);
+
+ return &tsfg->tsf;
+}
+
+static void ts_filter_group_destroy(struct platform_device *pdev,
+ struct ts_filter *tsf)
+{
+ struct ts_filter_group *tsfg = (struct ts_filter_group *)tsf;
+
+ kfree(tsfg->samples[0]); /* first guy has pointer from kmalloc */
+ kfree(tsf);
+}
+
+static void ts_filter_group_scale(struct ts_filter *tsf, int *coords)
+{
+ if (tsf->next)
+ (tsf->next->api->scale)(tsf->next, coords);
+}
+
+static int int_cmp(const void *_a, const void *_b)
+{
+ const int *a = _a;
+ const int *b = _b;
+
+ if (*a > *b)
+ return 1;
+ if (*a < *b)
+ return -1;
+ return 0;
+}
+
+static int ts_filter_group_process(struct ts_filter *tsf, int *coords)
+{
+ struct ts_filter_group *tsfg = (struct ts_filter_group *)tsf;
+ int n;
+ int i;
+ int ret = 0; /* ask for more samples by default */
+
+ BUG_ON(tsfg->N >= tsfg->config->extent);
+
+ for (n = 0; n < tsf->count_coords; n++)
+ tsfg->samples[n][tsfg->N] = coords[n];
+
+ if (++tsfg->N < tsfg->config->extent)
+ return 0; /* we meed more samples */
+
+ for (n = 0; n < tsfg->tsf.count_coords; n++) {
+ int *v = tsfg->sorted_samples;
+ int ngroups = 0;
+ int best_size;
+ int best_idx = 0;
+ int idx = 0;
+
+ memcpy(v, tsfg->samples[n], tsfg->N * sizeof(int));
+ sort(v, tsfg->N, sizeof(int), int_cmp, NULL);
+
+ tsfg->group_size[0] = 1;
+ for (i = 1; i < tsfg->N; ++i) {
+ if (v[i] - v[i - 1] <= tsfg->config->close_enough)
+ tsfg->group_size[ngroups]++;
+ else
+ tsfg->group_size[++ngroups] = 1;
+ }
+ ngroups++;
+
+ best_size = tsfg->group_size[0];
+ for (i = 1; i < ngroups; i++) {
+ idx += tsfg->group_size[i - 1];
+ if (best_size < tsfg->group_size[i]) {
+ best_size = tsfg->group_size[i];
+ best_idx = idx;
+ }
+ }
+
+ if (best_size < tsfg->config->threshold) {
+ /* this set is not good enough for us */
+ if (--tsfg->tries_left) {
+ ts_filter_group_clear_internal
+ (tsfg, tsfg->tries_left);
+ return 0; /* ask for more samples */
+ }
+ return -1; /* we give up */
+ }
+
+ tsfg->range_min[n] = v[best_idx];
+ tsfg->range_max[n] = v[best_idx + best_size - 1];
+ }
+
+ for (i = 0; i < tsfg->N; ++i) {
+ int r;
+
+ for (n = 0; n < tsfg->tsf.count_coords; ++n) {
+ coords[n] = tsfg->samples[n][i];
+ if (coords[n] < tsfg->range_min[n] ||
+ coords[n] > tsfg->range_max[n])
+ break;
+ }
+
+ if (n != tsfg->tsf.count_coords) /* sample not OK */
+ continue;
+
+ if (tsf->next) {
+ r = (tsf->next->api->process)(tsf->next, coords);
+ if (r) {
+ ret = r;
+ break;
+ }
+ } else if (i == tsfg->N - 1) {
+ ret = 1;
+ }
+ }
+
+ ts_filter_group_clear_internal(tsfg, tsfg->config->attempts);
+
+ return ret;
+}
+
+struct ts_filter_api ts_filter_group_api = {
+ .create = ts_filter_group_create,
+ .destroy = ts_filter_group_destroy,
+ .clear = ts_filter_group_clear,
+ .process = ts_filter_group_process,
+ .scale = ts_filter_group_scale,
+};
+
diff --git a/include/linux/ts_filter_group.h b/include/linux/ts_filter_group.h
new file mode 100644
index 0000000..1e74c8d
--- /dev/null
+++ b/include/linux/ts_filter_group.h
@@ -0,0 +1,39 @@
+#ifndef __TS_FILTER_GROUP_H__
+#define __TS_FILTER_GROUP_H__
+
+#include <linux/ts_filter.h>
+
+/*
+ * Touchscreen group filter.
+ *
+ * Copyright (C) 2008 by Openmoko, Inc.
+ * Author: Nelson Castillo <arhuaco@xxxxxxxxxxxxxxxxx>
+ *
+ */
+
+struct ts_filter_group_configuration {
+ int extent;
+ int close_enough;
+ int threshold;
+ int attempts;
+};
+
+struct ts_filter_group {
+ struct ts_filter tsf;
+ struct ts_filter_group_configuration *config;
+
+ int N; /* How many samples we have */
+ int *samples[MAX_TS_FILTER_COORDS]; /* the samples, our input */
+
+ int *group_size; /* used for temporal computations */
+ int *sorted_samples; /* used for temporal computations */
+
+ int range_max[MAX_TS_FILTER_COORDS]; /* max computed ranges */
+ int range_min[MAX_TS_FILTER_COORDS]; /* min computed ranges */
+
+ int tries_left; /* We finish if we don't get enough samples */
+};
+
+extern struct ts_filter_api ts_filter_group_api;
+
+#endif
--
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