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/* 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.
*
* AP state machine
*/
#include "ccd_config.h"
#include "common.h"
#include "console.h"
#include "gpio.h"
#include "hooks.h"
#include "system.h"
#define CPRINTS(format, args...) cprints(CC_SYSTEM, format, ## args)
static enum device_state state = DEVICE_STATE_INIT;
void print_ap_state(void)
{
ccprintf("AP: %s\n", device_state_name(state));
}
int ap_is_on(void)
{
/* Debouncing and on are both still on */
return (state == DEVICE_STATE_DEBOUNCING || state == DEVICE_STATE_ON);
}
/**
* Set the AP 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_on(), etc. do.
*
* @param new_state State to set.
*/
static void set_state(enum device_state new_state)
{
#ifdef CR50_DEBUG_AP_STATE
/* Print all state transitions. May spam the console. */
if (state != new_state)
CPRINTS("AP %s -> %s",
device_state_name(state), device_state_name(new_state));
#endif
state = new_state;
}
/**
* Set AP to the off state
*/
static void set_ap_off(void)
{
CPRINTS("AP off");
set_state(DEVICE_STATE_OFF);
/*
* If TPM is configured then the INT_AP_L signal is used as a low pulse
* trigger to sync transactions with the host. By default Cr50 is
* driving this line high, but when the AP powers off, the 1.8V rail
* that it's pulled up to will be off and cause excessive power to be
* consumed by the Cr50. Set INT_AP_L as an input while the AP is
* powered off.
*/
gpio_set_flags(GPIO_INT_AP_L, GPIO_INPUT);
ccd_update_state();
/*
* We don't enable deep sleep on ARM devices yet, as its processing
* there will require more support on the AP side than is available
* now.
*
* Note: Presence of platform reset is a poor indicator of deep sleep
* support. It happens to be correlated with ARM vs x86 at present.
*/
if (board_deep_sleep_allowed())
enable_deep_sleep();
}
/**
* Move the AP to the ON state
*/
static void set_ap_on(void)
{
CPRINTS("AP on");
set_state(DEVICE_STATE_ON);
/*
* AP is powering up, set the host sync signal to output and set it
* high which is the default level.
*/
gpio_set_flags(GPIO_INT_AP_L, GPIO_OUT_HIGH);
gpio_set_level(GPIO_INT_AP_L, 1);
ccd_update_state();
if (board_deep_sleep_allowed())
disable_deep_sleep();
}
/**
* Handle moving the AP to the OFF state from a deferred interrupt handler.
*
* Needs to make additional state checks to avoid double-on in case ap_detect()
* has run in the meantime.
*/
void set_ap_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 AP isn't already on, make it so */
if (state != DEVICE_STATE_ON)
set_ap_on();
}
DECLARE_DEFERRED(set_ap_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_on_deferred_data, 0);
}
/**
* Detect state machine
*/
static void ap_detect(void)
{
int detect;
if (board_detect_ap_with_tpm_rst()) {
/* AP is detected if platform reset is deasserted */
detect = gpio_get_level(GPIO_TPM_RST_L);
} else {
/* Disable interrupts if we had them on for debouncing */
gpio_disable_interrupt(GPIO_DETECT_AP);
/* AP is detected if it's driving its UART TX signal */
detect = gpio_get_level(GPIO_DETECT_AP);
}
/* Handle detecting device */
if (detect) {
/*
* If we were debouncing ON->OFF, cancel debouncing and go back
* to the ON state.
*/
if (state == DEVICE_STATE_DEBOUNCING)
set_state(DEVICE_STATE_ON);
/* If we're already ON, done */
if (state == DEVICE_STATE_ON)
return;
if (board_detect_ap_with_tpm_rst()) {
/*
* The platform reset handler has not run yet;
* otherwise, it would have already turned the AP on
* and we wouldn't get here.
*
* This can happen if the hook task calls ap_detect()
* before deferred_tpm_rst_isr(). In this case, the
* deferred handler is already pending so calling the
* ISR has no effect.
*
* But we may actually have missed the edge. In that
* case, calling the ISR makes sure we don't miss the
* reset. It will call set_ap_on_deferred() to move
* the AP to the ON state.
*/
CPRINTS("AP detect calling tpm_rst_deasserted()");
tpm_rst_deasserted(GPIO_TPM_RST_L);
} else {
/* We're responsible for setting the AP state to ON */
set_ap_on();
}
return;
} else if (!board_detect_ap_with_tpm_rst()) {
/*
* If the signal is low, cr50 will enter the debouncing state or
* off. Either way, cr50 is waiting for the signal to go high.
* Reenable the interrupt, so cr50 can immediately detect it
* instead of relying on the 1s polling.
*/
gpio_enable_interrupt(GPIO_DETECT_AP);
}
/* AP 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_off();
return;
}
/*
* Otherwise, we were on before and haven't detected the AP. But we
* don't know if that's because the AP is actually off, or because the
* AP UART is sending a 0-bit or temporarily asserting platform reset.
* 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_detect, HOOK_PRIO_DEFAULT);
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