| 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 Andy Green <andy@openmoko.com> |
| 17 | * |
| 18 | * |
| 19 | * Median averaging stuff. We sort incoming raw samples into an array of |
| 20 | * MEDIAN_SIZE length, discarding the oldest sample each time once we are full. |
| 21 | * We then return the sum of the middle three samples for X and Y. It means |
| 22 | * the final result must be divided by (3 * scaling factor) to correct for |
| 23 | * avoiding the repeated /3. |
| 24 | * |
| 25 | * This strongly rejects brief excursions away from a central point that is |
| 26 | * sticky in time compared to the excursion duration. |
| 27 | * |
| 28 | * Thanks to Dale Schumacher (who wrote some example code) and Carl-Daniel |
| 29 | * Halifinger who pointed out this would be a good method. |
| 30 | */ |
| 31 | |
| 32 | #include <linux/errno.h> |
| 33 | #include <linux/kernel.h> |
| 34 | #include <linux/slab.h> |
| 35 | #include <linux/touchscreen/ts_filter_median.h> |
| 36 | |
| 37 | struct ts_filter_median { |
| 38 | /* Private configuration. */ |
| 39 | struct ts_filter_median_configuration *config; |
| 40 | /* Generic Filter API. */ |
| 41 | struct ts_filter tsf; |
| 42 | |
| 43 | /* Count raw samples we get. */ |
| 44 | int samples_count; |
| 45 | /* |
| 46 | * Remember the last coordinates we got in order to know if |
| 47 | * we are moving slow or fast. |
| 48 | */ |
| 49 | int last_issued[MAX_TS_FILTER_COORDS]; |
| 50 | /* How many samples in the sort buffer are valid. */ |
| 51 | int valid; |
| 52 | /* Samples taken for median in sorted form. */ |
| 53 | int *sort[MAX_TS_FILTER_COORDS]; |
| 54 | /* Samples taken for median. */ |
| 55 | int *fifo[MAX_TS_FILTER_COORDS]; |
| 56 | /* Where we are in the fifo sample memory. */ |
| 57 | int pos; |
| 58 | /* Do we have a sample to deliver? */ |
| 59 | int ready; |
| 60 | }; |
| 61 | |
| 62 | #define ts_filter_to_filter_median(f) \ |
| 63 | container_of(f, struct ts_filter_median, tsf) |
| 64 | |
| 65 | |
| 66 | static void ts_filter_median_insert(int *p, int sample, int count) |
| 67 | { |
| 68 | int n; |
| 69 | |
| 70 | /* Search through what we got so far to find where to put sample. */ |
| 71 | for (n = 0; n < count; n++) |
| 72 | if (sample < p[n]) { /* We met somebody bigger than us? */ |
| 73 | /* Starting from the end, push bigger guys down one. */ |
| 74 | for (count--; count >= n; count--) |
| 75 | p[count + 1] = p[count]; |
| 76 | p[n] = sample; /* Put us in place of first bigger. */ |
| 77 | return; |
| 78 | } |
| 79 | |
| 80 | p[count] = sample; /* Nobody was bigger than us, add us on the end. */ |
| 81 | } |
| 82 | |
| 83 | static void ts_filter_median_del(int *p, int value, int count) |
| 84 | { |
| 85 | int index; |
| 86 | |
| 87 | for (index = 0; index < count; index++) |
| 88 | if (p[index] == value) { |
| 89 | for (; index < count; index++) |
| 90 | p[index] = p[index + 1]; |
| 91 | return; |
| 92 | } |
| 93 | } |
| 94 | |
| 95 | |
| 96 | static void ts_filter_median_clear(struct ts_filter *tsf) |
| 97 | { |
| 98 | struct ts_filter_median *tsfm = ts_filter_to_filter_median(tsf); |
| 99 | |
| 100 | tsfm->pos = 0; |
| 101 | tsfm->valid = 0; |
| 102 | tsfm->ready = 0; |
| 103 | memset(&tsfm->last_issued[0], 1, tsf->count_coords * sizeof(int)); |
| 104 | } |
| 105 | |
| 106 | static struct ts_filter *ts_filter_median_create( |
| 107 | struct platform_device *pdev, |
| 108 | const struct ts_filter_configuration *conf, |
| 109 | int count_coords) |
| 110 | { |
| 111 | int *p; |
| 112 | int n; |
| 113 | struct ts_filter_median *tsfm = kzalloc(sizeof(struct ts_filter_median), |
| 114 | GFP_KERNEL); |
| 115 | |
| 116 | if (!tsfm) |
| 117 | return NULL; |
| 118 | |
| 119 | tsfm->config = container_of(conf, |
| 120 | struct ts_filter_median_configuration, |
| 121 | config); |
| 122 | |
| 123 | tsfm->tsf.count_coords = count_coords; |
| 124 | |
| 125 | tsfm->config->midpoint = (tsfm->config->extent >> 1) + 1; |
| 126 | |
| 127 | p = kmalloc(2 * count_coords * sizeof(int) * (tsfm->config->extent + 1), |
| 128 | GFP_KERNEL); |
| 129 | if (!p) { |
| 130 | kfree(tsfm); |
| 131 | return NULL; |
| 132 | } |
| 133 | |
| 134 | for (n = 0; n < count_coords; n++) { |
| 135 | tsfm->sort[n] = p; |
| 136 | p += tsfm->config->extent + 1; |
| 137 | tsfm->fifo[n] = p; |
| 138 | p += tsfm->config->extent + 1; |
| 139 | } |
| 140 | |
| 141 | ts_filter_median_clear(&tsfm->tsf); |
| 142 | |
| 143 | dev_info(&pdev->dev, |
| 144 | "Created Median filter len:%d coords:%d dec_threshold:%d\n", |
| 145 | tsfm->config->extent, count_coords, |
| 146 | tsfm->config->decimation_threshold); |
| 147 | |
| 148 | return &tsfm->tsf; |
| 149 | } |
| 150 | |
| 151 | static void ts_filter_median_destroy(struct ts_filter *tsf) |
| 152 | { |
| 153 | struct ts_filter_median *tsfm = ts_filter_to_filter_median(tsf); |
| 154 | |
| 155 | kfree(tsfm->sort[0]); /* First guy has pointer from kmalloc. */ |
| 156 | kfree(tsf); |
| 157 | } |
| 158 | |
| 159 | static void ts_filter_median_scale(struct ts_filter *tsf, int *coords) |
| 160 | { |
| 161 | int n; |
| 162 | |
| 163 | for (n = 0; n < tsf->count_coords; n++) |
| 164 | coords[n] = (coords[n] + 2) / 3; |
| 165 | } |
| 166 | |
| 167 | /* |
| 168 | * Give us the raw sample data coords, and if we return 1 then you can |
| 169 | * get a filtered coordinate from coords. If we return 0 you didn't |
| 170 | * fill all the filters with samples yet. |
| 171 | */ |
| 172 | |
| 173 | static int ts_filter_median_process(struct ts_filter *tsf, int *coords) |
| 174 | { |
| 175 | struct ts_filter_median *tsfm = ts_filter_to_filter_median(tsf); |
| 176 | int n; |
| 177 | int movement = 1; |
| 178 | |
| 179 | for (n = 0; n < tsf->count_coords; n++) { |
| 180 | /* Grab copy in insertion order to remove when oldest. */ |
| 181 | tsfm->fifo[n][tsfm->pos] = coords[n]; |
| 182 | /* Insert these samples in sorted order in the median arrays. */ |
| 183 | ts_filter_median_insert(tsfm->sort[n], coords[n], tsfm->valid); |
| 184 | } |
| 185 | /* Move us on in the fifo. */ |
| 186 | if (++tsfm->pos == (tsfm->config->extent + 1)) |
| 187 | tsfm->pos = 0; |
| 188 | |
| 189 | /* Have we finished a median sampling? */ |
| 190 | if (++tsfm->valid < tsfm->config->extent) |
| 191 | goto process_exit; /* No valid sample to use. */ |
| 192 | |
| 193 | BUG_ON(tsfm->valid != tsfm->config->extent); |
| 194 | |
| 195 | tsfm->valid--; |
| 196 | |
| 197 | /* |
| 198 | * Sum the middle 3 in the median sorted arrays. We don't divide back |
| 199 | * down which increases the sum resolution by a factor of 3 until the |
| 200 | * scale API function is called. |
| 201 | */ |
| 202 | for (n = 0; n < tsf->count_coords; n++) |
| 203 | /* Perform the deletion of the oldest sample. */ |
| 204 | ts_filter_median_del(tsfm->sort[n], tsfm->fifo[n][tsfm->pos], |
| 205 | tsfm->valid); |
| 206 | |
| 207 | tsfm->samples_count--; |
| 208 | if (tsfm->samples_count >= 0) |
| 209 | goto process_exit; |
| 210 | |
| 211 | for (n = 0; n < tsf->count_coords; n++) { |
| 212 | /* Give the coordinate result from summing median 3. */ |
| 213 | coords[n] = tsfm->sort[n][tsfm->config->midpoint - 1] + |
| 214 | tsfm->sort[n][tsfm->config->midpoint] + |
| 215 | tsfm->sort[n][tsfm->config->midpoint + 1]; |
| 216 | |
| 217 | movement += abs(tsfm->last_issued[n] - coords[n]); |
| 218 | } |
| 219 | |
| 220 | if (movement > tsfm->config->decimation_threshold) /* Moving fast. */ |
| 221 | tsfm->samples_count = tsfm->config->decimation_above; |
| 222 | else |
| 223 | tsfm->samples_count = tsfm->config->decimation_below; |
| 224 | |
| 225 | memcpy(&tsfm->last_issued[0], coords, tsf->count_coords * sizeof(int)); |
| 226 | |
| 227 | tsfm->ready = 1; |
| 228 | |
| 229 | process_exit: |
| 230 | return 0; |
| 231 | } |
| 232 | |
| 233 | static int ts_filter_median_haspoint(struct ts_filter *tsf) |
| 234 | { |
| 235 | struct ts_filter_median *priv = ts_filter_to_filter_median(tsf); |
| 236 | |
| 237 | return priv->ready; |
| 238 | } |
| 239 | |
| 240 | static void ts_filter_median_getpoint(struct ts_filter *tsf, int *point) |
| 241 | { |
| 242 | struct ts_filter_median *priv = ts_filter_to_filter_median(tsf); |
| 243 | |
| 244 | BUG_ON(!priv->ready); |
| 245 | |
| 246 | memcpy(point, &priv->last_issued[0], tsf->count_coords * sizeof(int)); |
| 247 | |
| 248 | priv->ready = 0; |
| 249 | } |
| 250 | |
| 251 | const struct ts_filter_api ts_filter_median_api = { |
| 252 | .create = ts_filter_median_create, |
| 253 | .destroy = ts_filter_median_destroy, |
| 254 | .clear = ts_filter_median_clear, |
| 255 | .process = ts_filter_median_process, |
| 256 | .scale = ts_filter_median_scale, |
| 257 | .haspoint = ts_filter_median_haspoint, |
| 258 | .getpoint = ts_filter_median_getpoint, |
| 259 | }; |
| 260 | EXPORT_SYMBOL_GPL(ts_filter_median_api); |
| 261 | |
| 262 | |
