key_matrix.c
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/*
* Manage Keyboard Matrices
*
* Copyright (c) 2012 The Chromium OS Authors.
* (C) Copyright 2004 DENX Software Engineering, Wolfgang Denk, wd@denx.de
*
* SPDX-License-Identifier: GPL-2.0+
*/
#include <common.h>
#include <dm.h>
#include <key_matrix.h>
#include <malloc.h>
#include <linux/input.h>
/**
* Determine if the current keypress configuration can cause key ghosting
*
* We figure this out by seeing if we have two or more keys in the same
* column, as well as two or more keys in the same row.
*
* @param config Keyboard matrix config
* @param keys List of keys to check
* @param valid Number of valid keypresses to check
* @return 0 if no ghosting is possible, 1 if it is
*/
static int has_ghosting(struct key_matrix *config, struct key_matrix_key *keys,
int valid)
{
int key_in_same_col = 0, key_in_same_row = 0;
int i, j;
if (!config->ghost_filter || valid < 3)
return 0;
for (i = 0; i < valid; i++) {
/*
* Find 2 keys such that one key is in the same row
* and the other is in the same column as the i-th key.
*/
for (j = i + 1; j < valid; j++) {
if (keys[j].col == keys[i].col)
key_in_same_col = 1;
if (keys[j].row == keys[i].row)
key_in_same_row = 1;
}
}
if (key_in_same_col && key_in_same_row)
return 1;
else
return 0;
}
int key_matrix_decode(struct key_matrix *config, struct key_matrix_key keys[],
int num_keys, int keycode[], int max_keycodes)
{
const u8 *keymap;
int valid, upto;
int pos;
debug("%s: num_keys = %d\n", __func__, num_keys);
keymap = config->plain_keycode;
for (valid = upto = 0; upto < num_keys; upto++) {
struct key_matrix_key *key = &keys[upto];
debug(" valid=%d, row=%d, col=%d\n", key->valid, key->row,
key->col);
if (!key->valid)
continue;
pos = key->row * config->num_cols + key->col;
if (config->fn_keycode && pos == config->fn_pos)
keymap = config->fn_keycode;
/* Convert the (row, col) values into a keycode */
if (valid < max_keycodes)
keycode[valid++] = keymap[pos];
debug(" keycode=%d\n", keymap[pos]);
}
/* For a ghost key config, ignore the keypresses for this iteration. */
if (has_ghosting(config, keys, valid)) {
valid = 0;
debug(" ghosting detected!\n");
}
debug(" %d valid keycodes found\n", valid);
return valid;
}
/**
* Create a new keycode map from some provided data
*
* This decodes a keycode map in the format used by the fdt, which is one
* word per entry, with the row, col and keycode encoded in that word.
*
* We create a (row x col) size byte array with each entry containing the
* keycode for that (row, col). We also search for map_keycode and return
* its position if found (this is used for finding the Fn key).
*
* @param config Key matrix dimensions structure
* @param data Keycode data
* @param len Number of entries in keycode table
* @param map_keycode Key code to find in the map
* @param pos Returns position of map_keycode, if found, else -1
* @return map Pointer to allocated map
*/
static uchar *create_keymap(struct key_matrix *config, const u32 *data, int len,
int map_keycode, int *pos)
{
uchar *map;
if (pos)
*pos = -1;
map = (uchar *)calloc(1, config->key_count);
if (!map) {
debug("%s: failed to malloc %d bytes\n", __func__,
config->key_count);
return NULL;
}
for (; len >= sizeof(u32); data++, len -= 4) {
u32 tmp = fdt32_to_cpu(*data);
int key_code, row, col;
int entry;
row = (tmp >> 24) & 0xff;
col = (tmp >> 16) & 0xff;
key_code = tmp & 0xffff;
entry = row * config->num_cols + col;
map[entry] = key_code;
debug(" map %d, %d: pos=%d, keycode=%d\n", row, col,
entry, key_code);
if (pos && map_keycode == key_code)
*pos = entry;
}
return map;
}
int key_matrix_decode_fdt(struct udevice *dev, struct key_matrix *config)
{
const u32 *prop;
int proplen;
uchar *plain_keycode;
prop = dev_read_prop(dev, "linux,keymap", &proplen);
/* Basic keymap is required */
if (!prop) {
debug("%s: cannot find keycode-plain map\n", __func__);
return -1;
}
plain_keycode = create_keymap(config, prop, proplen, KEY_FN,
&config->fn_pos);
config->plain_keycode = plain_keycode;
/* Conversion error -> fail */
if (!config->plain_keycode)
return -1;
prop = dev_read_prop(dev, "linux,fn-keymap", &proplen);
/* fn keymap is optional */
if (!prop)
goto done;
config->fn_keycode = create_keymap(config, prop, proplen, -1, NULL);
/* Conversion error -> fail */
if (!config->fn_keycode) {
free(plain_keycode);
return -1;
}
done:
debug("%s: Decoded key maps %p, %p from fdt\n", __func__,
config->plain_keycode, config->fn_keycode);
return 0;
}
int key_matrix_init(struct key_matrix *config, int rows, int cols,
int ghost_filter)
{
memset(config, '\0', sizeof(*config));
config->num_rows = rows;
config->num_cols = cols;
config->key_count = rows * cols;
config->ghost_filter = ghost_filter;
assert(config->key_count > 0);
return 0;
}