include/key_matrix.h

   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 */
  13 struct 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 */
  30 struct 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  */
  55 int 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  */
  70 int 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  */
  81 int key_matrix_init(struct key_matrix *config, int rows, int cols,
  82                     int ghost_filter);
  83
  84 #endif