Add support for extra buttons not on the keyboard

BUG=chrome-os-partner:24370
BRANCH=tot
TEST=Run button unit test.

Orig-Change-Id: I61b4a6624d62831ce0bfdf7a0f36a45349b37f96
Signed-off-by: Dave Parker <dparker@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/184544
Reviewed-by: Randall Spangler <rspangler@chromium.org>
(cherry picked from commit f6426cc21c20a4f876cff28b9ce7e3115f0b054a)

Change-Id: I4face9bf0797a91ec8bef390093aab8e3d8f97ab
Reviewed-on: https://chromium-review.googlesource.com/185243
Tested-by: Randall Spangler <rspangler@chromium.org>
Reviewed-by: Bill Richardson <wfrichar@chromium.org>
Commit-Queue: Randall Spangler <rspangler@chromium.org>

1 files changed, 127 insertions, 0 deletions

diff --git a/common/button.c b/common/button.c
new file mode 100644
index 0000000000..2e48102dd3
--- /dev/null
+++ b/common/button.c
@@ -0,0 +1,127 @@
+/* Copyright (c) 2014 The Chromium OS Authors. All rights reserved.
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+/* Button module for Chrome EC */
+
+#include "button.h"
+#include "common.h"
+#include "console.h"
+#include "gpio.h"
+#include "hooks.h"
+#include "keyboard_protocol.h"
+#include "timer.h"
+#include "util.h"
+
+/* Console output macro */
+#define CPRINTF(format, args...) cprintf(CC_SWITCH, format, ## args)
+
+struct button_state_t {
+	uint64_t debounce_time;
+	int debounced_pressed;
+};
+
+static struct button_state_t state[CONFIG_BUTTON_COUNT];
+
+static uint64_t next_deferred_time;
+
+/*
+ * Whether a button is currently pressed.
+ */
+static int raw_button_pressed(const struct button_config *button)
+{
+	int raw_value = gpio_get_level(button->gpio);
+
+	return button->flags & BUTTON_FLAG_ACTIVE_HIGH ?
+				       raw_value : !raw_value;
+}
+
+/*
+ * Button initialization.
+ */
+static void button_init(void)
+{
+	int i;
+
+	CPRINTF("[%T (re)initializing buttons and interrupts.]\n");
+	next_deferred_time = 0;
+	for (i = 0; i < CONFIG_BUTTON_COUNT; i++) {
+		state[i].debounced_pressed = raw_button_pressed(&buttons[i]);
+		state[i].debounce_time = 0;
+		gpio_enable_interrupt(buttons[i].gpio);
+	}
+}
+DECLARE_HOOK(HOOK_INIT, button_init, HOOK_PRIO_DEFAULT);
+
+/*
+ * Handle debounced button changing state.
+ */
+static void button_change_deferred(void)
+{
+	int i;
+	int new_pressed;
+	uint64_t soonest_debounce_time = 0;
+	uint64_t time_now = get_time().val;
+
+	for (i = 0; i < CONFIG_BUTTON_COUNT; i++) {
+		/* Skip this button if we are not waiting to debounce */
+		if (state[i].debounce_time == 0)
+			continue;
+
+		if (state[i].debounce_time <= time_now) {
+			/* Check if the state has changed */
+			new_pressed = raw_button_pressed(&buttons[i]);
+			if (state[i].debounced_pressed != new_pressed) {
+				state[i].debounced_pressed = new_pressed;
+				CPRINTF("[%T Button '%s' was %s]\n",
+					buttons[i].name, new_pressed ?
+					"pressed" : "released");
+				keyboard_update_button(buttons[i].type,
+					new_pressed);
+			}
+
+			/* Clear the debounce time to stop checking it */
+			state[i].debounce_time = 0;
+		} else {
+			/*
+			 * Make sure the next deferred call happens on or before
+			 * each button needs it.
+			 */
+			soonest_debounce_time = (soonest_debounce_time == 0) ?
+				state[i].debounce_time :
+				MIN(soonest_debounce_time,
+				    state[i].debounce_time);
+		}
+	}
+
+	if (soonest_debounce_time != 0) {
+		next_deferred_time = soonest_debounce_time;
+		hook_call_deferred(button_change_deferred,
+				   next_deferred_time - time_now);
+	}
+}
+DECLARE_DEFERRED(button_change_deferred);
+
+/*
+ * Handle a button interrupt.
+ */
+void button_interrupt(enum gpio_signal signal)
+{
+	int i;
+	uint64_t time_now = get_time().val;
+
+	for (i = 0; i < CONFIG_BUTTON_COUNT; i++) {
+		if (buttons[i].gpio != signal)
+			continue;
+
+		state[i].debounce_time = time_now + buttons[i].debounce_us;
+		if (next_deferred_time <= time_now ||
+		    next_deferred_time > state[i].debounce_time) {
+			next_deferred_time = state[i].debounce_time;
+			hook_call_deferred(button_change_deferred,
+					   next_deferred_time - time_now);
+		}
+		break;
+	}
+}