/*
   * Keyboard matrix helper functions
   *
   * Copyright (c) 2012 The Chromium OS Authors.
   *
   * SPDX-License-Identifier:	GPL-2.0+
   */
  
  #ifndef _KEY_MATRIX_H
  #define _KEY_MATRIX_H
  
  #include <common.h>
  
  /* Information about a matrix keyboard */
  struct key_matrix {
  	/* Dimensions of the keyboard matrix, in rows and columns */
  	int num_rows;
  	int num_cols;
  	int key_count;	/* number of keys in the matrix (= rows * cols) */
  
  	/*
  	 * Information about keycode mappings. The plain_keycode array must
  	 * exist but fn may be NULL in which case it is not decoded.
  	 */
  	const u8 *plain_keycode;        /* key code for each row / column */
  	const u8 *fn_keycode;           /* ...when Fn held down */
  	int fn_pos;                     /* position of Fn key in key (or -1) */
  	int ghost_filter;		/* non-zero to enable ghost filter */
  };
  
  /* Information about a particular key (row, column pair) in the matrix */
  struct key_matrix_key {
  	uint8_t row;	/* row number (0 = first) */
  	uint8_t col;	/* column number (0 = first) */
  	uint8_t valid;	/* 1 if valid, 0 to ignore this */
  };
  
  /**
   * Decode a set of pressed keys into key codes
   *
   * Given a list of keys that are pressed, this converts this list into
   * a list of key codes. Each of the keys has a valid flag, which can be
   * used to mark a particular key as invalid (so that it is ignored).
   *
   * The plain keymap is used, unless the Fn key is detected along the way,
   * at which point we switch to the Fn key map.
   *
   * If key ghosting is detected, we simply ignore the keys and return 0.
   *
   * @param config        Keyboard matrix config
   * @param keys		List of keys to process (each is row, col)
   * @param num_keys	Number of keys to process
   * @param keycode	Returns a list of key codes, decoded from input
   * @param max_keycodes	Size of key codes array (suggest 8)
   *
   */
  int key_matrix_decode(struct key_matrix *config, struct key_matrix_key *keys,
  		      int num_keys, int keycode[], int max_keycodes);
  
  /**
   * Read the keyboard configuration out of the fdt.
   *
   * Decode properties of named "linux,<type>keymap" where <type> is either
   * empty, or "fn-". Then set up the plain key map (and the FN keymap if
   * present).
   *
   * @param config        Keyboard matrix config
   * @param blob          FDT blob
   * @param node          Node containing compatible data
   * @return 0 if ok, -1 on error
   */
  int key_matrix_decode_fdt(struct key_matrix *config, const void *blob,
  			  int node);
  
  /**
   * Set up a new key matrix.
   *
   * @param config	Keyboard matrix config
   * @param rows		Number of rows in key matrix
   * @param cols		Number of columns in key matrix
   * @param ghost_filter	Non-zero to enable ghost filtering
   * @return 0 if ok, -1 on error
   */
  int key_matrix_init(struct key_matrix *config, int rows, int cols,
  		    int ghost_filter);
  
  #endif