diff options
Diffstat (limited to 'drivers/input/touchscreen/ts_filter_group.c')
| -rw-r--r-- | drivers/input/touchscreen/ts_filter_group.c | 330 |
1 files changed, 330 insertions, 0 deletions
diff --git a/drivers/input/touchscreen/ts_filter_group.c b/drivers/input/touchscreen/ts_filter_group.c new file mode 100644 index 00000000000..722e8dfbdae --- /dev/null +++ b/drivers/input/touchscreen/ts_filter_group.c @@ -0,0 +1,330 @@ +/* + * 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) 2008,2009 by Openmoko, Inc. + * Author: Nelson Castillo <arhuaco@freaks-unidos.net> + * 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. + * This filter mixes information from all the available dimensions. It means + * that for two dimensions we draw a rectangle where the thought-to-be good + * points can be found. + * + * The implementation would be more efficient with a double-linked list but + * let's keep it simple for now. + * + * 1) We collect S samples and keep it in sorted sets. + * - Points that are "close enough" are considered to be in the same set. + * We don't actually keep the sets but ranges of points. + * + * 2) For each dimension: + * - We choose the range with more elements. If more than "threshold" + * points are in this range we use the minimum and the maximum point + * of the range to define the valid range for this dimension [min, max], + * otherwise we discard all the points and the ranges 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 "ts_filter_group.h" + +struct coord_range { + int min; /* Minimum value of the range. */ + int max; /* Maximum value of the range */ + int N; /* Number of points in the range. */ +}; + +struct ts_filter_group { + /* Private filter configuration. */ + struct ts_filter_group_configuration *config; + /* Filter API. */ + struct ts_filter tsf; + + int N; /* How many samples we have. */ + int *samples[MAX_TS_FILTER_COORDS]; /* The samples: our input. */ + + /* Temporal values that help us compute range_min and range_max. */ + struct coord_range *ranges[MAX_TS_FILTER_COORDS]; /* Ranges. */ + int n_ranges[MAX_TS_FILTER_COORDS]; /* Number of ranges */ + + /* Computed ranges that help us filter the points. */ + 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 can't get enough samples. */ + int ready; /* If we are ready to deliver samples. */ + int result; /* Index of the point being returned. */ +}; + +#define ts_filter_to_filter_group(f) \ + container_of(f, struct ts_filter_group, tsf) + + +static void ts_filter_group_clear_internal(struct ts_filter_group *tsfg, + int attempts) +{ + int n; + tsfg->N = 0; + tsfg->tries_left = attempts; + tsfg->ready = 0; + tsfg->result = 0; + for (n = 0; n < tsfg->tsf.count_coords; n++) + tsfg->n_ranges[n] = 0; +} + +static void ts_filter_group_clear(struct ts_filter *tsf) +{ + struct ts_filter_group *tsfg = ts_filter_to_filter_group(tsf); + + ts_filter_group_clear_internal(tsfg, tsfg->config->attempts); +} + +static struct ts_filter *ts_filter_group_create( + struct platform_device *pdev, + const struct ts_filter_configuration *conf, + int count_coords) +{ + struct ts_filter_group *tsfg; + int i; + + tsfg = kzalloc(sizeof(struct ts_filter_group), GFP_KERNEL); + if (!tsfg) + return NULL; + + tsfg->config = container_of(conf, + struct ts_filter_group_configuration, + config); + tsfg->tsf.count_coords = count_coords; + + BUG_ON(tsfg->config->attempts <= 0); + BUG_ON(tsfg->config->length < tsfg->config->threshold); + + tsfg->samples[0] = kmalloc(count_coords * sizeof(int) * + tsfg->config->length, 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->length; + + tsfg->ranges[0] = kmalloc(count_coords * sizeof(struct coord_range) * + tsfg->config->length, GFP_KERNEL); + if (!tsfg->ranges[0]) { + kfree(tsfg->samples[0]); + kfree(tsfg); + return NULL; + } + for (i = 1; i < count_coords; ++i) + tsfg->ranges[i] = tsfg->ranges[0] + i * tsfg->config->length; + + ts_filter_group_clear_internal(tsfg, tsfg->config->attempts); + + dev_info(&pdev->dev, "Created Group filter len:%d coords:%d close:%d " + "thresh:%d\n", tsfg->config->length, count_coords, + tsfg->config->close_enough, tsfg->config->threshold); + + return &tsfg->tsf; +} + +static void ts_filter_group_destroy(struct ts_filter *tsf) +{ + struct ts_filter_group *tsfg = ts_filter_to_filter_group(tsf); + + kfree(tsfg->samples[0]); + kfree(tsfg->ranges[0]); + kfree(tsf); +} + +static void ts_filter_group_prepare_next(struct ts_filter *tsf); + +#define MIN(a, b) ((a) < (b) ? (a) : (b)) +#define MAX(a, b) ((a) > (b) ? (a) : (b)) +#define IN_RANGE(c, r) ((c) >= (r).min - tsfg->config->close_enough && \ + (c) <= (r).max + tsfg->config->close_enough) + +static void delete_spot(struct coord_range *v, int n, int size) +{ + int i; + for (i = n; i < size - 1; ++i) + v[i] = v[i + 1]; +} + +static int ts_filter_group_process(struct ts_filter *tsf, int *coords) +{ + struct ts_filter_group *tsfg = ts_filter_to_filter_group(tsf); + int n; + int j; + + BUG_ON(tsfg->N >= tsfg->config->length); + BUG_ON(tsfg->ready); + + for (n = 0; n < tsfg->tsf.count_coords; n++) { + int i; + struct coord_range *range = tsfg->ranges[n]; + int *n_ranges = &tsfg->n_ranges[n]; + int found = 0; + + tsfg->samples[n][tsfg->N] = coords[n]; + + for (i = 0; i < *n_ranges; ++i) { + if (IN_RANGE(coords[n], range[i])) { + range[i].min = MIN(range[i].min, coords[n]); + range[i].max = MAX(range[i].max, coords[n]); + range[i].N++; + found = 1; + break; + } else if (coords[n] <= range[i].min) + break; /* We need to insert a range. */ + } + if (found) { /* We might need to melt ranges. */ + if (i && range[i - 1].max + tsfg->config->close_enough + >= range[i].min) { + BUG_ON(range[i - 1].max >= range[i].max); + range[i - 1].max = range[i].max; + range[i - 1].N += range[i].N; + delete_spot(range, i, *n_ranges); + (*n_ranges)--; + i--; + } + if (i < *n_ranges - 1 && range[i + 1].min - + tsfg->config->close_enough <= range[i].max) { + range[i].max = range[i + 1].max; + range[i].N += range[i + 1].N; + delete_spot(range, i + 1, *n_ranges); + (*n_ranges)--; + } + } else { + BUG_ON((*n_ranges) >= tsfg->config->length); + (*n_ranges)++; + for (j = *n_ranges - 1; j > i; --j) + range[j] = range[j - 1]; + range[i].N = 1; + range[i].min = coords[n]; + range[i].max = coords[n]; + } + } + + if (++tsfg->N < tsfg->config->length) + return 0; + + for (n = 0; n < tsfg->tsf.count_coords; ++n) { + int best = 0; + for (j = 1; j < tsfg->n_ranges[n]; ++j) + if (tsfg->ranges[n][best].N < tsfg->ranges[n][j].N) + best = j; + if (tsfg->ranges[n][best].N < tsfg->config->threshold) { + /* This set of points is not good enough for us. */ + if (--tsfg->tries_left) { + ts_filter_group_clear_internal + (tsfg, tsfg->tries_left); + /* No errors but we need more samples. */ + return 0; + } + return 1; /* We give up: error. */ + } + tsfg->range_min[n] = tsfg->ranges[n][best].min; + tsfg->range_max[n] = tsfg->ranges[n][best].max; + } + + ts_filter_group_prepare_next(tsf); + + return 0; +} + +/* + * This private function prepares a point that will be returned + * in ts_filter_group_getpoint if it is available. It updates + * the priv->ready state also. + */ +static void ts_filter_group_prepare_next(struct ts_filter *tsf) +{ + struct ts_filter_group *priv = ts_filter_to_filter_group(tsf); + int n; + + while (priv->result < priv->N) { + for (n = 0; n < priv->tsf.count_coords; ++n) { + if (priv->samples[n][priv->result] < + priv->range_min[n] || + priv->samples[n][priv->result] > priv->range_max[n]) + break; + } + + if (n == priv->tsf.count_coords) /* Sample is OK. */ + break; + + priv->result++; + } + + if (unlikely(priv->result >= priv->N)) { /* No sample to deliver. */ + ts_filter_group_clear_internal(priv, priv->config->attempts); + priv->ready = 0; + } else { + priv->ready = 1; + } +} + +static int ts_filter_group_haspoint(struct ts_filter *tsf) +{ + struct ts_filter_group *priv = ts_filter_to_filter_group(tsf); + + return priv->ready; +} + +static void ts_filter_group_getpoint(struct ts_filter *tsf, int *point) +{ + struct ts_filter_group *priv = ts_filter_to_filter_group(tsf); + int n; + + BUG_ON(!priv->ready); + + for (n = 0; n < priv->tsf.count_coords; n++) + point[n] = priv->samples[n][priv->result]; + + priv->result++; + + /* This call will update priv->ready. */ + ts_filter_group_prepare_next(tsf); +} + +/* + * Get ready to process the next batch of points, forget + * points we could have delivered. + */ +static void ts_filter_group_scale(struct ts_filter *tsf, int *coords) +{ + struct ts_filter_group *priv = ts_filter_to_filter_group(tsf); + + ts_filter_group_clear_internal(priv, priv->config->attempts); +} + +const 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, + .haspoint = ts_filter_group_haspoint, + .getpoint = ts_filter_group_getpoint, + .scale = ts_filter_group_scale, +}; +EXPORT_SYMBOL_GPL(ts_filter_group_api); + |