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/* Copyright 2020 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.
*/
/* CCD Measure SBU */
#include "adc.h"
#include "console.h"
#include "gpio.h"
#include "hooks.h"
#include "ioexpanders.h"
#include "timer.h"
#define CPRINTS(format, args...) cprints(CC_SYSTEM, format, ## args)
#define CPRINTF(format, args...) cprintf(CC_SYSTEM, format, ## args)
/*
* Define voltage thresholds for SBU USB detection.
*
* Max observed USB low across sampled systems: 666mV
* Min observed USB high across sampled systems: 3026mV
*/
#define GND_MAX_MV 700
#define USB_HIGH_MV 2500
#define SBU_DIRECT 0
#define SBU_FLIP 1
#define MODE_SBU_DISCONNECT 0
#define MODE_SBU_CONNECT 1
#define MODE_SBU_FLIP 2
#define MODE_SBU_OTHER 3
static void ccd_measure_sbu(void);
DECLARE_DEFERRED(ccd_measure_sbu);
static void ccd_measure_sbu(void)
{
int sbu1;
int sbu2;
int mux_en;
static int count /* = 0 */;
static int last /* = 0 */;
static int polarity /* = 0 */;
/* Read sbu voltage levels */
sbu1 = adc_read_channel(ADC_SBU1_DET);
sbu2 = adc_read_channel(ADC_SBU2_DET);
mux_en = gpio_get_level(GPIO_SBU_MUX_EN);
/*
* While SBU_MUX is disabled (SuzyQ unplugged), we'll poll the SBU lines
* to check if an idling, unconfigured USB device is present.
* USB FS pulls one line high for connect request.
* If so, and it persists for 500ms, we'll enable the SuzyQ in that
* orientation.
*/
if ((!mux_en) && (sbu1 > USB_HIGH_MV) && (sbu2 < GND_MAX_MV)) {
/* Check flip connection polarity. */
if (last != MODE_SBU_FLIP) {
last = MODE_SBU_FLIP;
polarity = SBU_FLIP;
count = 0;
} else {
count++;
}
} else if ((!mux_en) && (sbu2 > USB_HIGH_MV) && (sbu1 < GND_MAX_MV)) {
/* Check direct connection polarity. */
if (last != MODE_SBU_CONNECT) {
last = MODE_SBU_CONNECT;
polarity = SBU_DIRECT;
count = 0;
} else {
count++;
}
/*
* If SuzyQ is enabled, we'll poll for a persistent no-signal
* for 500ms. Since USB is differential, we should never see
* GND/GND while the device is connected.
* If disconnected, electrically remove SuzyQ.
*/
} else if ((mux_en) && (sbu1 < GND_MAX_MV) && (sbu2 < GND_MAX_MV)) {
/* Check for SBU disconnect if connected. */
if (last != MODE_SBU_DISCONNECT) {
last = MODE_SBU_DISCONNECT;
count = 0;
} else {
count++;
}
} else {
/* Didn't find anything, reset state. */
last = MODE_SBU_OTHER;
count = 0;
}
/*
* We have seen a new state continuously for 500ms.
* Let's update the mux to enable/disable SuzyQ appropriately.
*/
if (count > 5) {
if (mux_en) {
/* Disable mux as it's disconnected now. */
gpio_set_level(GPIO_SBU_MUX_EN, 0);
msleep(10);
CPRINTS("CCD: disconnected.");
} else {
/* SBU flip = polarity */
sbu_flip_sel(polarity);
gpio_set_level(GPIO_SBU_MUX_EN, 1);
msleep(10);
CPRINTS("CCD: connected %s",
polarity ? "flip" : "noflip");
}
}
/* Measure every 100ms, forever. */
hook_call_deferred(&ccd_measure_sbu_data, 100 * MSEC);
}
void ccd_enable(int enable)
{
if (enable) {
hook_call_deferred(&ccd_measure_sbu_data, 0);
} else {
gpio_set_level(GPIO_SBU_MUX_EN, 0);
hook_call_deferred(&ccd_measure_sbu_data, -1);
}
}
void start_ccd_meas_sbu_cycle(void)
{
hook_call_deferred(&ccd_measure_sbu_data, 1000 * MSEC);
}
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