1 // SPDX-License-Identifier: GPL-2.0+
3 * Manage Keyboard Matrices
5 * Copyright (c) 2012 The Chromium OS Authors.
6 * (C) Copyright 2004 DENX Software Engineering, Wolfgang Denk, wd@denx.de
11 #include <key_matrix.h>
13 #include <linux/input.h>
16 * Determine if the current keypress configuration can cause key ghosting
18 * We figure this out by seeing if we have two or more keys in the same
19 * column, as well as two or more keys in the same row.
21 * @param config Keyboard matrix config
22 * @param keys List of keys to check
23 * @param valid Number of valid keypresses to check
24 * @return 0 if no ghosting is possible, 1 if it is
26 static int has_ghosting(struct key_matrix *config, struct key_matrix_key *keys,
29 int key_in_same_col = 0, key_in_same_row = 0;
32 if (!config->ghost_filter || valid < 3)
35 for (i = 0; i < valid; i++) {
37 * Find 2 keys such that one key is in the same row
38 * and the other is in the same column as the i-th key.
40 for (j = i + 1; j < valid; j++) {
41 if (keys[j].col == keys[i].col)
43 if (keys[j].row == keys[i].row)
48 if (key_in_same_col && key_in_same_row)
54 int key_matrix_decode(struct key_matrix *config, struct key_matrix_key keys[],
55 int num_keys, int keycode[], int max_keycodes)
61 debug("%s: num_keys = %d\n", __func__, num_keys);
62 keymap = config->plain_keycode;
63 for (valid = upto = 0; upto < num_keys; upto++) {
64 struct key_matrix_key *key = &keys[upto];
66 debug(" valid=%d, row=%d, col=%d\n", key->valid, key->row,
70 pos = key->row * config->num_cols + key->col;
71 if (config->fn_keycode && pos == config->fn_pos)
72 keymap = config->fn_keycode;
74 /* Convert the (row, col) values into a keycode */
75 if (valid < max_keycodes)
76 keycode[valid++] = keymap[pos];
77 debug(" keycode=%d\n", keymap[pos]);
80 /* For a ghost key config, ignore the keypresses for this iteration. */
81 if (has_ghosting(config, keys, valid)) {
83 debug(" ghosting detected!\n");
85 debug(" %d valid keycodes found\n", valid);
91 * Create a new keycode map from some provided data
93 * This decodes a keycode map in the format used by the fdt, which is one
94 * word per entry, with the row, col and keycode encoded in that word.
96 * We create a (row x col) size byte array with each entry containing the
97 * keycode for that (row, col). We also search for map_keycode and return
98 * its position if found (this is used for finding the Fn key).
100 * @param config Key matrix dimensions structure
101 * @param data Keycode data
102 * @param len Number of entries in keycode table
103 * @param map_keycode Key code to find in the map
104 * @param pos Returns position of map_keycode, if found, else -1
105 * @return map Pointer to allocated map
107 static uchar *create_keymap(struct key_matrix *config, const u32 *data, int len,
108 int map_keycode, int *pos)
114 map = (uchar *)calloc(1, config->key_count);
116 debug("%s: failed to malloc %d bytes\n", __func__,
121 for (; len >= sizeof(u32); data++, len -= 4) {
122 u32 tmp = fdt32_to_cpu(*data);
123 int key_code, row, col;
126 row = (tmp >> 24) & 0xff;
127 col = (tmp >> 16) & 0xff;
128 key_code = tmp & 0xffff;
129 entry = row * config->num_cols + col;
130 map[entry] = key_code;
131 debug(" map %d, %d: pos=%d, keycode=%d\n", row, col,
133 if (pos && map_keycode == key_code)
140 int key_matrix_decode_fdt(struct udevice *dev, struct key_matrix *config)
144 uchar *plain_keycode;
146 prop = dev_read_prop(dev, "linux,keymap", &proplen);
147 /* Basic keymap is required */
149 debug("%s: cannot find keycode-plain map\n", __func__);
153 plain_keycode = create_keymap(config, prop, proplen, KEY_FN,
155 config->plain_keycode = plain_keycode;
156 /* Conversion error -> fail */
157 if (!config->plain_keycode)
160 prop = dev_read_prop(dev, "linux,fn-keymap", &proplen);
161 /* fn keymap is optional */
165 config->fn_keycode = create_keymap(config, prop, proplen, -1, NULL);
166 /* Conversion error -> fail */
167 if (!config->fn_keycode) {
173 debug("%s: Decoded key maps %p, %p from fdt\n", __func__,
174 config->plain_keycode, config->fn_keycode);
178 int key_matrix_init(struct key_matrix *config, int rows, int cols,
181 memset(config, '\0', sizeof(*config));
182 config->num_rows = rows;
183 config->num_cols = cols;
184 config->key_count = rows * cols;
185 config->ghost_filter = ghost_filter;
186 assert(config->key_count > 0);