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/* Copyright 2018 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.
*
* AP UART state machine
*/
#include "ccd_config.h"
#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;
void print_ap_uart_state(void)
{
ccprintf("AP UART: %s\n", device_state_name(state));
}
int ap_uart_is_on(void)
{
/* Debouncing and on are both still on */
return (state == DEVICE_STATE_DEBOUNCING || state == DEVICE_STATE_ON);
}
/**
* Set the AP UART state.
*
* Done as a function to make it easier to debug state transitions. Note that
* this ONLY sets the state (and possibly prints debug info), and doesn't do
* all the additional transition work that set_ap_uart_on(), etc. do.
*
* @param new_state State to set.
*/
static void set_state(enum device_state new_state)
{
#ifdef CR50_DEBUG_AP_UART_STATE
/* Print all state transitions. May spam the console. */
if (state != new_state)
CPRINTS("AP UART %s -> %s",
device_state_name(state), device_state_name(new_state));
#endif
state = new_state;
}
/* Move the AP UART to the OFF state. */
static void set_ap_uart_off(void)
{
CPRINTS("AP UART off");
set_state(DEVICE_STATE_OFF);
ccd_update_state();
}
/**
* Move the AP UART 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_ap_uart_on_deferred(void)
{
/* If we were debouncing ON->OFF, cancel it because we're still on */
if (state == DEVICE_STATE_DEBOUNCING)
set_state(DEVICE_STATE_ON);
/* If we're already on, done */
if (state == DEVICE_STATE_ON)
return;
/* We were previously off */
CPRINTS("AP UART on");
set_state(DEVICE_STATE_ON);
ccd_update_state();
}
DECLARE_DEFERRED(set_ap_uart_on_deferred);
/**
* Interrupt handler for AP detect asserted
*/
void ap_detect_asserted(enum gpio_signal signal)
{
gpio_disable_interrupt(GPIO_DETECT_AP);
hook_call_deferred(&set_ap_uart_on_deferred_data, 0);
}
/**
* Detect state machine
*/
static void ap_uart_detect(void)
{
/* Disable interrupts if we had them on for debouncing */
gpio_disable_interrupt(GPIO_DETECT_AP);
/* If the AP UART signal is high, make sure it's on */
if (gpio_get_level(GPIO_DETECT_AP)) {
hook_call_deferred(&set_ap_uart_on_deferred_data, 0);
return;
}
/*
* Make sure the interrupt is enabled. We will need to detect the on
* transition if we enter the off or debouncing state
*/
gpio_enable_interrupt(GPIO_DETECT_AP);
/* AP UART 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) {
set_ap_uart_off();
return;
}
/*
* Otherwise, we were on or initializing, and we're not sure if the AP
* UART is actually off or just sending a 0-bit. So start debouncing.
*/
if (state == DEVICE_STATE_INIT)
set_state(DEVICE_STATE_INIT_DEBOUNCING);
else
set_state(DEVICE_STATE_DEBOUNCING);
}
DECLARE_HOOK(HOOK_SECOND, ap_uart_detect, HOOK_PRIO_DEFAULT);
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