1/* SPDX-License-Identifier: GPL-2.0+ */
2/*
3 * Keyboard matrix helper functions
4 *
5 * Copyright (c) 2012 The Chromium OS Authors.
6 */
7
8#ifndef _KEY_MATRIX_H
9#define _KEY_MATRIX_H
10
11
12/* Information about a matrix keyboard */
13struct key_matrix {
14	/* Dimensions of the keyboard matrix, in rows and columns */
15	int num_rows;
16	int num_cols;
17	int key_count;	/* number of keys in the matrix (= rows * cols) */
18
19	/*
20	 * Information about keycode mappings. The plain_keycode array must
21	 * exist but fn may be NULL in which case it is not decoded.
22	 */
23	const u8 *plain_keycode;        /* key code for each row / column */
24	const u8 *fn_keycode;           /* ...when Fn held down */
25	int fn_pos;                     /* position of Fn key in key (or -1) */
26	int ghost_filter;		/* non-zero to enable ghost filter */
27};
28
29/* Information about a particular key (row, column pair) in the matrix */
30struct key_matrix_key {
31	uint8_t row;	/* row number (0 = first) */
32	uint8_t col;	/* column number (0 = first) */
33	uint8_t valid;	/* 1 if valid, 0 to ignore this */
34};
35
36/**
37 * Decode a set of pressed keys into key codes
38 *
39 * Given a list of keys that are pressed, this converts this list into
40 * a list of key codes. Each of the keys has a valid flag, which can be
41 * used to mark a particular key as invalid (so that it is ignored).
42 *
43 * The plain keymap is used, unless the Fn key is detected along the way,
44 * at which point we switch to the Fn key map.
45 *
46 * If key ghosting is detected, we simply ignore the keys and return 0.
47 *
48 * @param config        Keyboard matrix config
49 * @param keys		List of keys to process (each is row, col)
50 * @param num_keys	Number of keys to process
51 * @param keycode	Returns a list of key codes, decoded from input
52 * @param max_keycodes	Size of key codes array (suggest 8)
53 *
54 */
55int key_matrix_decode(struct key_matrix *config, struct key_matrix_key *keys,
56		      int num_keys, int keycode[], int max_keycodes);
57
58/**
59 * Read the keyboard configuration out of the fdt.
60 *
61 * Decode properties of named "linux,<type>keymap" where <type> is either
62 * empty, or "fn-". Then set up the plain key map (and the FN keymap if
63 * present).
64 *
65 * @param config        Keyboard matrix config
66 * @param blob          FDT blob
67 * @param node          Node containing compatible data
68 * Return: 0 if ok, -1 on error
69 */
70int key_matrix_decode_fdt(struct udevice *dev, struct key_matrix *config);
71
72/**
73 * Set up a new key matrix.
74 *
75 * @param config	Keyboard matrix config
76 * @param rows		Number of rows in key matrix
77 * @param cols		Number of columns in key matrix
78 * @param ghost_filter	Non-zero to enable ghost filtering
79 * Return: 0 if ok, -1 on error
80 */
81int key_matrix_init(struct key_matrix *config, int rows, int cols,
82		    int ghost_filter);
83
84#endif
85