1 files changed, 112 insertions, 0 deletions
diff --git a/board/cr50/ec_state.c b/board/cr50/ec_state.c
new file mode 100644
index 0000000000..5958ea3b79
--- /dev/null
+++ b/board/cr50/ec_state.c
@@ -0,0 +1,112 @@
+/* Copyright 2017 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.
+ *
+ * EC detect state machine.
+ */
+#include "common.h"
+#include "console.h"
+#include "gpio.h"
+#include "hooks.h"
+#include "uart_bitbang.h"
+#include "uartn.h"
+
+#define CPRINTS(format, args...) cprints(CC_SYSTEM, format, ## args)
+
+static enum device_state state = DEVICE_STATE_INIT;
+
+int ec_is_on(void)
+{
+	/* Debouncing and on are both still on */
+	return (state == DEVICE_STATE_DEBOUNCING || state == DEVICE_STATE_ON);
+}
+
+/**
+ * Move the EC to the ON state.
+ *
+ * This can be deferred from the interrupt handler, or called from the state
+ * machine which also runs in HOOK task, so it needs to check the current state
+ * to determine whether we're already on.
+ */
+static void set_ec_on(void)
+{
+	if (state == DEVICE_STATE_INIT ||
+	    state == DEVICE_STATE_INIT_DEBOUNCING) {
+		/*
+		 * Enable the UART peripheral so we start receiving on EC RX,
+		 * but do not call uartn_tx_connect() to connect EC TX yet.  We
+		 * need to be able to use EC TX to detect servo, so if we drive
+		 * it right away that blocks us from detecting servo.
+		 */
+		CPRINTS("EC RX only");
+		if (!uart_bitbang_is_enabled(UART_EC))
+			uartn_enable(UART_EC);
+		state = DEVICE_STATE_INIT_RX_ONLY;
+		return;
+	}
+
+	/* If we were debouncing ON->OFF, cancel it because we're still on */
+	if (state == DEVICE_STATE_DEBOUNCING)
+		state = DEVICE_STATE_ON;
+
+	/* If we're already on, done */
+	if (state == DEVICE_STATE_ON)
+		return;
+
+	/* We were previously off */
+	CPRINTS("EC on");
+	state = DEVICE_STATE_ON;
+
+	/* Enable UART RX if we're not bit-banging */
+	if (!uart_bitbang_is_enabled(UART_EC))
+		enable_ccd_uart(UART_EC);
+}
+DECLARE_DEFERRED(set_ec_on);
+
+/**
+ * Interrupt handler for EC detect asserted.
+ */
+void ec_detect_asserted(enum gpio_signal signal)
+{
+	gpio_disable_interrupt(GPIO_DETECT_EC);
+	hook_call_deferred(&set_ec_on_data, 0);
+}
+
+/**
+ * Detect state machine
+ */
+static void ec_detect(void)
+{
+	/* Disable interrupts if we had them on for debouncing */
+	gpio_disable_interrupt(GPIO_DETECT_EC);
+
+	/* If we detect the EC, make sure it's on */
+	if (gpio_get_level(GPIO_DETECT_EC)) {
+		set_ec_on();
+		return;
+	}
+
+	/* EC wasn't detected.  If we're already off, done. */
+	if (state == DEVICE_STATE_OFF)
+		return;
+
+	/* If we were debouncing, we're now sure we're off */
+	if (state == DEVICE_STATE_DEBOUNCING ||
+	    state == DEVICE_STATE_INIT_DEBOUNCING) {
+		CPRINTS("EC off");
+		state = DEVICE_STATE_OFF;
+		disable_ccd_uart(UART_EC);
+		return;
+	}
+
+	/*
+	 * Otherwise, we were on or initializing, and we're not sure if the EC
+	 * is actually off or just sending a 0-bit.  So start debouncing.
+	 */
+	if (state == DEVICE_STATE_INIT)
+		state = DEVICE_STATE_INIT_DEBOUNCING;
+	else
+		state = DEVICE_STATE_DEBOUNCING;
+	gpio_enable_interrupt(GPIO_DETECT_EC);
+}
+DECLARE_HOOK(HOOK_SECOND, ec_detect, HOOK_PRIO_DEFAULT);