| 1 | /* |
| 2 | * This program is free software; you can redistribute it and/or modify |
| 3 | * it under the terms of the GNU General Public License as published by |
| 4 | * the Free Software Foundation; either version 2 of the License, or |
| 5 | * (at your option) any later version. |
| 6 | * |
| 7 | * This program is distributed in the hope that it will be useful, |
| 8 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 9 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 10 | * GNU General Public License for more details. |
| 11 | * |
| 12 | * You should have received a copy of the GNU General Public License |
| 13 | * along with this program; if not, write to the Free Software |
| 14 | * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA |
| 15 | * |
| 16 | * Copyright (C) 2008,2009 by Openmoko, Inc. |
| 17 | * Author: Nelson Castillo <arhuaco@freaks-unidos.net> |
| 18 | * All rights reserved. |
| 19 | * |
| 20 | * |
| 21 | * This filter is useful to reject samples that are not reliable. We consider |
| 22 | * that a sample is not reliable if it deviates form the Majority. |
| 23 | * |
| 24 | * 1) We collect S samples. |
| 25 | * |
| 26 | * 2) For each dimension: |
| 27 | * |
| 28 | * - We sort the points. |
| 29 | * - Points that are "close enough" are considered to be in the same set. |
| 30 | * - We choose the set with more elements. If more than "threshold" |
| 31 | * points are in this set we use the first and the last point of the set |
| 32 | * to define the valid range for this dimension [min, max], otherwise we |
| 33 | * discard all the points and go to step 1. |
| 34 | * |
| 35 | * 3) We consider the unsorted S samples and try to feed them to the next |
| 36 | * filter in the chain. If one of the points of each sample |
| 37 | * is not in the allowed range for its dimension, we discard the sample. |
| 38 | * |
| 39 | */ |
| 40 | |
| 41 | #include <linux/kernel.h> |
| 42 | #include <linux/slab.h> |
| 43 | #include <linux/sort.h> |
| 44 | #include <linux/touchscreen/ts_filter_group.h> |
| 45 | |
| 46 | struct ts_filter_group { |
| 47 | /* Private filter configuration. */ |
| 48 | struct ts_filter_group_configuration *config; |
| 49 | /* Filter API. */ |
| 50 | struct ts_filter tsf; |
| 51 | |
| 52 | int N; /* How many samples we have. */ |
| 53 | int *samples[MAX_TS_FILTER_COORDS]; /* The samples: our input. */ |
| 54 | |
| 55 | int *group_size; /* Used for temporal computations. */ |
| 56 | int *sorted_samples; /* Used for temporal computations. */ |
| 57 | |
| 58 | int range_max[MAX_TS_FILTER_COORDS]; /* Max. computed ranges. */ |
| 59 | int range_min[MAX_TS_FILTER_COORDS]; /* Min. computed ranges. */ |
| 60 | |
| 61 | int tries_left; /* We finish if we don't get enough samples. */ |
| 62 | int ready; /* If we are ready to deliver samples. */ |
| 63 | int result; /* Index of the point being returned. */ |
| 64 | }; |
| 65 | |
| 66 | #define ts_filter_to_filter_group(f) \ |
| 67 | container_of(f, struct ts_filter_group, tsf) |
| 68 | |
| 69 | |
| 70 | static void ts_filter_group_clear_internal(struct ts_filter_group *tsfg, |
| 71 | int attempts) |
| 72 | { |
| 73 | tsfg->N = 0; |
| 74 | tsfg->tries_left = attempts; |
| 75 | tsfg->ready = 0; |
| 76 | tsfg->result = 0; |
| 77 | } |
| 78 | |
| 79 | static void ts_filter_group_clear(struct ts_filter *tsf) |
| 80 | { |
| 81 | struct ts_filter_group *tsfg = ts_filter_to_filter_group(tsf); |
| 82 | |
| 83 | ts_filter_group_clear_internal(tsfg, tsfg->config->attempts); |
| 84 | } |
| 85 | |
| 86 | static struct ts_filter *ts_filter_group_create( |
| 87 | struct platform_device *pdev, |
| 88 | const struct ts_filter_configuration *conf, |
| 89 | int count_coords) |
| 90 | { |
| 91 | struct ts_filter_group *tsfg; |
| 92 | int i; |
| 93 | |
| 94 | tsfg = kzalloc(sizeof(struct ts_filter_group), GFP_KERNEL); |
| 95 | if (!tsfg) |
| 96 | return NULL; |
| 97 | |
| 98 | tsfg->config = container_of(conf, |
| 99 | struct ts_filter_group_configuration, |
| 100 | config); |
| 101 | tsfg->tsf.count_coords = count_coords; |
| 102 | |
| 103 | BUG_ON(tsfg->config->attempts <= 0); |
| 104 | |
| 105 | tsfg->samples[0] = kmalloc((2 + count_coords) * sizeof(int) * |
| 106 | tsfg->config->length, GFP_KERNEL); |
| 107 | if (!tsfg->samples[0]) { |
| 108 | kfree(tsfg); |
| 109 | return NULL; |
| 110 | } |
| 111 | for (i = 1; i < count_coords; ++i) |
| 112 | tsfg->samples[i] = tsfg->samples[0] + i * tsfg->config->length; |
| 113 | tsfg->sorted_samples = tsfg->samples[0] + count_coords * |
| 114 | tsfg->config->length; |
| 115 | tsfg->group_size = tsfg->samples[0] + (1 + count_coords) * |
| 116 | tsfg->config->length; |
| 117 | |
| 118 | ts_filter_group_clear_internal(tsfg, tsfg->config->attempts); |
| 119 | |
| 120 | dev_info(&pdev->dev, "Created Group filter len:%d coords:%d close:%d " |
| 121 | "thresh:%d\n", tsfg->config->length, count_coords, |
| 122 | tsfg->config->close_enough, tsfg->config->threshold); |
| 123 | |
| 124 | return &tsfg->tsf; |
| 125 | } |
| 126 | |
| 127 | static void ts_filter_group_destroy(struct ts_filter *tsf) |
| 128 | { |
| 129 | struct ts_filter_group *tsfg = ts_filter_to_filter_group(tsf); |
| 130 | |
| 131 | kfree(tsfg->samples[0]); /* first guy has pointer from kmalloc */ |
| 132 | kfree(tsf); |
| 133 | } |
| 134 | |
| 135 | static int int_cmp(const void *_a, const void *_b) |
| 136 | { |
| 137 | const int *a = _a; |
| 138 | const int *b = _b; |
| 139 | |
| 140 | if (*a > *b) |
| 141 | return 1; |
| 142 | if (*a < *b) |
| 143 | return -1; |
| 144 | return 0; |
| 145 | } |
| 146 | |
| 147 | static void ts_filter_group_prepare_next(struct ts_filter *tsf); |
| 148 | |
| 149 | static int ts_filter_group_process(struct ts_filter *tsf, int *coords) |
| 150 | { |
| 151 | struct ts_filter_group *tsfg = ts_filter_to_filter_group(tsf); |
| 152 | int n; |
| 153 | int i; |
| 154 | |
| 155 | BUG_ON(tsfg->N >= tsfg->config->length); |
| 156 | BUG_ON(tsfg->ready); |
| 157 | |
| 158 | for (n = 0; n < tsf->count_coords; n++) |
| 159 | tsfg->samples[n][tsfg->N] = coords[n]; |
| 160 | |
| 161 | if (++tsfg->N < tsfg->config->length) |
| 162 | return 0; /* We need more samples. */ |
| 163 | |
| 164 | for (n = 0; n < tsfg->tsf.count_coords; n++) { |
| 165 | int *v = tsfg->sorted_samples; |
| 166 | int ngroups = 0; |
| 167 | int best_size; |
| 168 | int best_idx = 0; |
| 169 | int idx = 0; |
| 170 | |
| 171 | memcpy(v, tsfg->samples[n], tsfg->N * sizeof(int)); |
| 172 | /* |
| 173 | * FIXME: Remove this sort call. We already have the |
| 174 | * algorithm for this modification. The filter will |
| 175 | * need less points (about half) if there is not a |
| 176 | * lot of noise. Right now we are doing a constant |
| 177 | * amount of work no matter how much noise we are |
| 178 | * dealing with. |
| 179 | */ |
| 180 | sort(v, tsfg->N, sizeof(int), int_cmp, NULL); |
| 181 | |
| 182 | tsfg->group_size[0] = 1; |
| 183 | for (i = 1; i < tsfg->N; ++i) { |
| 184 | if (v[i] - v[i - 1] <= tsfg->config->close_enough) |
| 185 | tsfg->group_size[ngroups]++; |
| 186 | else |
| 187 | tsfg->group_size[++ngroups] = 1; |
| 188 | } |
| 189 | ngroups++; |
| 190 | |
| 191 | best_size = tsfg->group_size[0]; |
| 192 | for (i = 1; i < ngroups; i++) { |
| 193 | idx += tsfg->group_size[i - 1]; |
| 194 | if (best_size < tsfg->group_size[i]) { |
| 195 | best_size = tsfg->group_size[i]; |
| 196 | best_idx = idx; |
| 197 | } |
| 198 | } |
| 199 | |
| 200 | if (best_size < tsfg->config->threshold) { |
| 201 | /* This set is not good enough for us. */ |
| 202 | if (--tsfg->tries_left) { |
| 203 | ts_filter_group_clear_internal |
| 204 | (tsfg, tsfg->tries_left); |
| 205 | /* No errors but we need more samples. */ |
| 206 | return 0; |
| 207 | } |
| 208 | return 1; /* We give up: error. */ |
| 209 | } |
| 210 | |
| 211 | tsfg->range_min[n] = v[best_idx]; |
| 212 | tsfg->range_max[n] = v[best_idx + best_size - 1]; |
| 213 | } |
| 214 | |
| 215 | ts_filter_group_prepare_next(tsf); |
| 216 | |
| 217 | return 0; |
| 218 | } |
| 219 | |
| 220 | /* |
| 221 | * This private function prepares a point that will be returned |
| 222 | * in ts_filter_group_getpoint if it is available. It updates |
| 223 | * the priv->ready state also. |
| 224 | */ |
| 225 | static void ts_filter_group_prepare_next(struct ts_filter *tsf) |
| 226 | { |
| 227 | struct ts_filter_group *priv = ts_filter_to_filter_group(tsf); |
| 228 | int n; |
| 229 | |
| 230 | while (priv->result < priv->N) { |
| 231 | for (n = 0; n < priv->tsf.count_coords; ++n) { |
| 232 | if (priv->samples[n][priv->result] < |
| 233 | priv->range_min[n] || |
| 234 | priv->samples[n][priv->result] > priv->range_max[n]) |
| 235 | break; |
| 236 | } |
| 237 | |
| 238 | if (n == priv->tsf.count_coords) /* Sample is OK. */ |
| 239 | break; |
| 240 | |
| 241 | priv->result++; |
| 242 | } |
| 243 | |
| 244 | if (unlikely(priv->result >= priv->N)) { /* No sample to deliver. */ |
| 245 | ts_filter_group_clear_internal(priv, priv->config->attempts); |
| 246 | priv->ready = 0; |
| 247 | } else { |
| 248 | priv->ready = 1; |
| 249 | } |
| 250 | } |
| 251 | |
| 252 | static int ts_filter_group_haspoint(struct ts_filter *tsf) |
| 253 | { |
| 254 | struct ts_filter_group *priv = ts_filter_to_filter_group(tsf); |
| 255 | |
| 256 | return priv->ready; |
| 257 | } |
| 258 | |
| 259 | static void ts_filter_group_getpoint(struct ts_filter *tsf, int *point) |
| 260 | { |
| 261 | struct ts_filter_group *priv = ts_filter_to_filter_group(tsf); |
| 262 | int n; |
| 263 | |
| 264 | BUG_ON(!priv->ready); |
| 265 | |
| 266 | for (n = 0; n < priv->tsf.count_coords; n++) |
| 267 | point[n] = priv->samples[n][priv->result]; |
| 268 | |
| 269 | priv->result++; |
| 270 | |
| 271 | /* This call will update priv->ready. */ |
| 272 | ts_filter_group_prepare_next(tsf); |
| 273 | } |
| 274 | |
| 275 | /* |
| 276 | * Get ready to process the next batch of points, forget |
| 277 | * points we could have delivered. |
| 278 | */ |
| 279 | static void ts_filter_group_scale(struct ts_filter *tsf, int *coords) |
| 280 | { |
| 281 | struct ts_filter_group *priv = ts_filter_to_filter_group(tsf); |
| 282 | |
| 283 | ts_filter_group_clear_internal(priv, priv->config->attempts); |
| 284 | } |
| 285 | |
| 286 | const struct ts_filter_api ts_filter_group_api = { |
| 287 | .create = ts_filter_group_create, |
| 288 | .destroy = ts_filter_group_destroy, |
| 289 | .clear = ts_filter_group_clear, |
| 290 | .process = ts_filter_group_process, |
| 291 | .haspoint = ts_filter_group_haspoint, |
| 292 | .getpoint = ts_filter_group_getpoint, |
| 293 | .scale = ts_filter_group_scale, |
| 294 | }; |
| 295 | EXPORT_SYMBOL_GPL(ts_filter_group_api); |
| 296 | |
| 297 | |
