[U-Boot] [PATCH v4 04/10] input: Add support for keyboard matrix decoding from an fdt

Simon Glass
2012-04-17T19:01:31Z

From: Bernie Thompson <bhthompson@chromium.org>

Matrix keyboards require a key map to be set up, and must also deal with
key ghosting.

Create a keyboard matrix management implementation which can be leveraged
by various keyboard drivers. This includes code to read the keymap from
the FDT and perform debouncing.

Signed-off-by: Bernie Thompson <bhthompson@chromium.org>
Signed-off-by: Simon Glass <sjg@chromium.org>
---
Changes in v4:
- Move matrix keyboard handling into a separate module

drivers/input/Makefile | 1 +
drivers/input/key_matrix.c | 208 ++++++++++++++++++++++++++++++++++++++++++++
include/key_matrix.h | 99 +++++++++++++++++++++
3 files changed, 308 insertions(+), 0 deletions(-)
create mode 100644 drivers/input/key_matrix.c
create mode 100644 include/key_matrix.h

diff --git a/drivers/input/Makefile b/drivers/input/Makefile
index d06acb9..b8d8623 100644
--- a/drivers/input/Makefile
+++ b/drivers/input/Makefile
@@ -31,6 +31,7 @@ COBJS-y += keyboard.o pc_keyb.o
COBJS-$(CONFIG_PS2MULT) += ps2mult.o ps2ser.o
endif
COBJS-y += input.o
+COBJS-y += key_matrix.o

COBJS := $(COBJS-y)
SRCS := $(COBJS:.o=.c)
diff --git a/drivers/input/key_matrix.c b/drivers/input/key_matrix.c
new file mode 100644
index 0000000..84b898f
--- /dev/null
+++ b/drivers/input/key_matrix.c
@@ -0,0 +1,208 @@
+/*
+ * Manage Keyboard Matrices
+ *
+ * Copyright (c) 2012 The Chromium OS Authors.
+ * (C) Copyright 2004 DENX Software Engineering, Wolfgang Denk, wd at denx.de
+ *
+ * See file CREDITS for list of people who contributed to this
+ * project.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of
+ * the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
+ * MA 02111-1307 USA
+ */
+
+#include <fdtdec.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;
+
+ 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 (valid >= 3 && 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, 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;
+ if (pos && map_keycode == key_code)
+ *pos = entry;
+ }
+
+ return map;
+}
+
+int key_matrix_decode_fdt(struct key_matrix *config, const void *blob,
+ int node)
+{
+ const struct fdt_property *prop;
+ int offset;
+
+ /* Check each property name for ones that we understand */
+ for (offset = fdt_first_property_offset(blob, node);
+ offset > 0;
+ offset = fdt_next_property_offset(blob, offset)) {
+ const char *name;
+ int len;
+
+ prop = fdt_get_property_by_offset(blob, offset, NULL);
+ name = fdt_string(blob, fdt32_to_cpu(prop->nameoff));
+ len = strlen(name);
+
+ /* Name needs to match "1,<type>keymap" */
+ debug("%s: property '%s'\n", __func__, name);
+ if (strncmp(name, "1,", 2) || len < 8 ||
+ strcmp(name + len - 6, "keymap"))
+ continue;
+
+ len -= 8;
+ if (len == 0) {
+ config->plain_keycode = create_keymap(config,
+ (u32 *)prop->data, fdt32_to_cpu(prop->len),
+ KEY_FN, &config->fn_pos);
+ } else if (0 == strncmp(name + 2, "fn-", len)) {
+ config->fn_keycode = create_keymap(config,
+ (u32 *)prop->data, fdt32_to_cpu(prop->len),
+ -1, NULL);
+ } else {
+ debug("%s: unrecognised property '%s'\n", __func__,
+ name);
+ }
+ }
+ debug("%s: Decoded key maps %p, %p from fdt\n", __func__,
+ config->plain_keycode, config->fn_keycode);
+
+ if (!config->plain_keycode) {
+ debug("%s: cannot find keycode-plain map\n", __func__);
+ return -1;
+ }
+
+ return 0;
+}
+
+int key_matrix_init(struct key_matrix *config, int rows, int cols)
+{
+ memset(config, '\0', sizeof(*config));
+ config->num_rows = rows;
+ config->num_cols = cols;
+ config->key_count = rows * cols;
+ assert(config->key_count > 0);
+
+ return 0;
+}
diff --git a/include/key_matrix.h b/include/key_matrix.h
new file mode 100644
index 0000000..f413314
--- /dev/null
+++ b/include/key_matrix.h
@@ -0,0 +1,99 @@
+/*
+ * Keyboard matrix helper functions
+ *
+ * Copyright (c) 2012 The Chromium OS Authors.
+ * See file CREDITS for list of people who contributed to this
+ * project.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of
+ * the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
+ * MA 02111-1307 USA
+ */
+
+#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) */
+};
+
+/* 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
+ * @return 0 if ok, -1 on error
+ */
+int key_matrix_init(struct key_matrix *config, int rows, int cols);
+
+#endif
--
1.7.7.3