Add skeleton for multiple keyboard handling backends

This defines the API the keyboard backends will need to implement. It is
based on what's in input_xkb.h but cleaned up and simplified.

Signed-off-by: Ran Benita <ran234@gmail.com>
Signed-off-by: David Herrmann <dh.herrmann@googlemail.com>

src/kbd.h

@@ -0,0 +1,88 @@
+/*
+ * kmscon - translating key presses to input events
+ *
+ * Copyright (c) 2012 Ran Benita <ran234@gmail.com>
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining
+ * a copy of this software and associated documentation files
+ * (the "Software"), to deal in the Software without restriction, including
+ * without limitation the rights to use, copy, modify, merge, publish,
+ * distribute, sublicense, and/or sell copies of the Software, and to
+ * permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included
+ * in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+ * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+ * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
+ * CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
+ * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
+ * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+/*
+ * This defines the API the keyboard backends need to implement. The main
+ * function of a keyboard backend is to translate a kernel input event into a
+ * kmscon_input_event (see kmscon_kbd_process_key function).
+ *
+ * The two exported object are a "keyboard" object and a "keyboard
+ * description" object. The keyboard object holds all the device specific
+ * private state (e.g. active groups, modifiers). The description object
+ * holds all the global information (e.g. layouts, mapping tables).
+ */
+
+#ifndef KMSCON_KBD_H
+#define KMSCON_KBD_H
+
+#include <inttypes.h>
+#include "input.h"
+
+struct kmscon_kbd_desc;
+struct kmscon_kbd;
+
+/*
+ * These are the values sent by the kernel in the /value/ field of the
+ * /input_event/ struct.
+ * See Documentation/input/event-codes.txt in the kernel tree.
+ */
+enum kmscon_key_state {
+	KMSCON_KEY_RELEASED = 0,
+	KMSCON_KEY_PRESSED = 1,
+	KMSCON_KEY_REPEATED = 2,
+};
+
+int kmscon_kbd_desc_new(struct kmscon_kbd_desc **out, const char *layout,
+				const char *variant, const char *options);
+void kmscon_kbd_desc_ref(struct kmscon_kbd_desc *desc);
+void kmscon_kbd_desc_unref(struct kmscon_kbd_desc *desc);
+
+int kmscon_kbd_new(struct kmscon_kbd **out, struct kmscon_kbd_desc *desc);
+void kmscon_kbd_ref(struct kmscon_kbd *state);
+void kmscon_kbd_unref(struct kmscon_kbd *state);
+
+/*
+ * This resets the keyboard state in case it got out of sync. It's mainly used
+ * to sync our notion of the keyboard state with what the keyboard LEDs show.
+ */
+void kmscon_kbd_reset(struct kmscon_kbd *kbd, int evdev_fd);
+
+/*
+ * This is the entry point to the keyboard processing.
+ * We get an evdev scancode and the keyboard state, and should put out a
+ * proper input event.
+ * Some evdev input events shouldn't result in us sending an input event
+ * (e.g. a key release):
+ * - If the event was filled out, 0 is returned.
+ * - Otherwise, if there was no error, -ENOKEY is returned.
+ */
+int kmscon_kbd_process_key(struct kmscon_kbd *kbd,
+					enum kmscon_key_state key_state,
+					uint16_t code,
+					struct kmscon_input_event *out);
+
+void kmscon_kbd_keysym_to_string(uint32_t keysym, char *str, size_t size);
+
+#endif /* KMSCON_KBD_H */