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diff --git a/include/key_matrix.h b/include/key_matrix.h
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+/* SPDX-License-Identifier: GPL-2.0+ */
+/*
+ * Keyboard matrix helper functions
+ *
+ * Copyright (c) 2012 The Chromium OS Authors.
+ */
+
+#ifndef _KEY_MATRIX_H
+#define _KEY_MATRIX_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 udevice *dev, struct key_matrix *config);
+
+/**
+ * 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