drivers/input/key_matrix.c

   1 /*
   2  * Manage Keyboard Matrices
   3  *
   4  * Copyright (c) 2012 The Chromium OS Authors.
   5  * (C) Copyright 2004 DENX Software Engineering, Wolfgang Denk, wd@denx.de
   6  *
   7  * See file CREDITS for list of people who contributed to this
   8  * project.
   9  *
  10  * This program is free software; you can redistribute it and/or
  11  * modify it under the terms of the GNU General Public License as
  12  * published by the Free Software Foundation; either version 2 of
  13  * the License, or (at your option) any later version.
  14  *
  15  * This program is distributed in the hope that it will be useful,
  16  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  17  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  18  * GNU General Public License for more details.
  19  *
  20  * You should have received a copy of the GNU General Public License
  21  * along with this program; if not, write to the Free Software
  22  * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
  23  * MA 02111-1307 USA
  24  */
  25
  26 #include <common.h>
  27 #include <fdtdec.h>
  28 #include <key_matrix.h>
  29 #include <malloc.h>
  30 #include <linux/input.h>
  31
  32 /**
  33  * Determine if the current keypress configuration can cause key ghosting
  34  *
  35  * We figure this out by seeing if we have two or more keys in the same
  36  * column, as well as two or more keys in the same row.
  37  *
  38  * @param config        Keyboard matrix config
  39  * @param keys          List of keys to check
  40  * @param valid         Number of valid keypresses to check
  41  * @return 0 if no ghosting is possible, 1 if it is
  42  */
  43 static int has_ghosting(struct key_matrix *config, struct key_matrix_key *keys,
  44                         int valid)
  45 {
  46         int key_in_same_col = 0, key_in_same_row = 0;
  47         int i, j;
  48
  49         if (!config->ghost_filter || valid < 3)
  50                 return 0;
  51
  52         for (i = 0; i < valid; i++) {
  53                 /*
  54                  * Find 2 keys such that one key is in the same row
  55                  * and the other is in the same column as the i-th key.
  56                  */
  57                 for (j = i + 1; j < valid; j++) {
  58                         if (keys[j].col == keys[i].col)
  59                                 key_in_same_col = 1;
  60                         if (keys[j].row == keys[i].row)
  61                                 key_in_same_row = 1;
  62                 }
  63         }
  64
  65         if (key_in_same_col && key_in_same_row)
  66                 return 1;
  67         else
  68                 return 0;
  69 }
  70
  71 int key_matrix_decode(struct key_matrix *config, struct key_matrix_key keys[],
  72                       int num_keys, int keycode[], int max_keycodes)
  73 {
  74         const u8 *keymap;
  75         int valid, upto;
  76         int pos;
  77
  78         debug("%s: num_keys = %d\n", __func__, num_keys);
  79         keymap = config->plain_keycode;
  80         for (valid = upto = 0; upto < num_keys; upto++) {
  81                 struct key_matrix_key *key = &keys[upto];
  82
  83                 debug("  valid=%d, row=%d, col=%d\n", key->valid, key->row,
  84                       key->col);
  85                 if (!key->valid)
  86                         continue;
  87                 pos = key->row * config->num_cols + key->col;
  88                 if (config->fn_keycode && pos == config->fn_pos)
  89                         keymap = config->fn_keycode;
  90
  91                 /* Convert the (row, col) values into a keycode */
  92                 if (valid < max_keycodes)
  93                         keycode[valid++] = keymap[pos];
  94                 debug("    keycode=%d\n", keymap[pos]);
  95         }
  96
  97         /* For a ghost key config, ignore the keypresses for this iteration. */
  98         if (has_ghosting(config, keys, valid)) {
  99                 valid = 0;
 100                 debug("    ghosting detected!\n");
 101         }
 102         debug("  %d valid keycodes found\n", valid);
 103
 104         return valid;
 105 }
 106
 107 /**
 108  * Create a new keycode map from some provided data
 109  *
 110  * This decodes a keycode map in the format used by the fdt, which is one
 111  * word per entry, with the row, col and keycode encoded in that word.
 112  *
 113  * We create a (row x col) size byte array with each entry containing the
 114  * keycode for that (row, col). We also search for map_keycode and return
 115  * its position if found (this is used for finding the Fn key).
 116  *
 117  * @param config        Key matrix dimensions structure
 118  * @param data          Keycode data
 119  * @param len           Number of entries in keycode table
 120  * @param map_keycode   Key code to find in the map
 121  * @param pos           Returns position of map_keycode, if found, else -1
 122  * @return map  Pointer to allocated map
 123  */
 124 static uchar *create_keymap(struct key_matrix *config, u32 *data, int len,
 125                             int map_keycode, int *pos)
 126 {
 127         uchar *map;
 128
 129         if (pos)
 130                 *pos = -1;
 131         map = (uchar *)calloc(1, config->key_count);
 132         if (!map) {
 133                 debug("%s: failed to malloc %d bytes\n", __func__,
 134                         config->key_count);
 135                 return NULL;
 136         }
 137
 138         for (; len >= sizeof(u32); data++, len -= 4) {
 139                 u32 tmp = fdt32_to_cpu(*data);
 140                 int key_code, row, col;
 141                 int entry;
 142
 143                 row = (tmp >> 24) & 0xff;
 144                 col = (tmp >> 16) & 0xff;
 145                 key_code = tmp & 0xffff;
 146                 entry = row * config->num_cols + col;
 147                 map[entry] = key_code;
 148                 debug("   map %d, %d: pos=%d, keycode=%d\n", row, col,
 149                       entry, key_code);
 150                 if (pos && map_keycode == key_code)
 151                         *pos = entry;
 152         }
 153
 154         return map;
 155 }
 156
 157 int key_matrix_decode_fdt(struct key_matrix *config, const void *blob, int node)
 158 {
 159         const struct fdt_property *prop;
 160         int proplen;
 161         uchar *plain_keycode;
 162
 163         prop = fdt_get_property(blob, node, "linux,keymap", &proplen);
 164         /* Basic keymap is required */
 165         if (!prop) {
 166                 debug("%s: cannot find keycode-plain map\n", __func__);
 167                 return -1;
 168         }
 169
 170         plain_keycode = create_keymap(config, (u32 *)prop->data,
 171                 proplen, KEY_FN, &config->fn_pos);
 172         config->plain_keycode = plain_keycode;
 173         /* Conversion error -> fail */
 174         if (!config->plain_keycode)
 175                 return -1;
 176
 177         prop = fdt_get_property(blob, node, "linux,fn-keymap", &proplen);
 178         /* fn keymap is optional */
 179         if (!prop)
 180                 goto done;
 181
 182         config->fn_keycode = create_keymap(config, (u32 *)prop->data,
 183                 proplen, -1, NULL);
 184         /* Conversion error -> fail */
 185         if (!config->fn_keycode) {
 186                 free(plain_keycode);
 187                 return -1;
 188         }
 189
 190 done:
 191         debug("%s: Decoded key maps %p, %p from fdt\n", __func__,
 192               config->plain_keycode, config->fn_keycode);
 193         return 0;
 194 }
 195
 196 int key_matrix_init(struct key_matrix *config, int rows, int cols,
 197                     int ghost_filter)
 198 {
 199         memset(config, '\0', sizeof(*config));
 200         config->num_rows = rows;
 201         config->num_cols = cols;
 202         config->key_count = rows * cols;
 203         config->ghost_filter = ghost_filter;
 204         assert(config->key_count > 0);
 205
 206         return 0;
 207 }