spring: keep the charger in idle mode when VBUS is cut

When the Spring charger is cutting internally VBUS,
we keep the current limit to 0A until the user unplugs and replugs the
power supply.

Signed-off-by: Vincent Palatin <vpalatin@chromium.org>

BRANCH=spring
BUG=none
TEST=On Spring, use a power supply with a switch on the 5V wire and
simulate VBUS going on and off :
- 5V OFF then ON : ILIM = 0A
- 5V OFF then ON, then unplug, then re-plug : ILIM = 2.5A
- 5V OFF, then unplug, then re-plug : ILIM = 2.5A

Change-Id: Icdc87eb5b6e746b0e89aadf19606efc07fb2bbc9
Reviewed-on: https://chromium-review.googlesource.com/176553
Reviewed-by: Vincent Palatin <vpalatin@chromium.org>
Commit-Queue: Vincent Palatin <vpalatin@chromium.org>
Tested-by: Vincent Palatin <vpalatin@chromium.org>

1 files changed, 50 insertions, 1 deletions

diff --git a/board/spring/usb_charging.c b/board/spring/usb_charging.c
index 74da3cdd1f..f4c1add354 100644
--- a/board/spring/usb_charging.c
+++ b/board/spring/usb_charging.c
@@ -80,6 +80,9 @@
 /* Delay before notifying kernel of device type change */
 #define BATTERY_KEY_DELAY (PWM_CTRL_OC_DETECT_TIME + 400 * MSEC)
 
+/* Delay to read again ID pin when VBUS went off */
+#define ID_REDETECTION_DELAY 200000
+
 /* Delay for signals to settle */
 #define DELAY_POWER_MS		20
 #define DELAY_USB_DP_DN_MS	20
@@ -104,6 +107,7 @@ static int pending_adc_watchdog_disable;
 static int pending_dev_type_update;
 static int pending_video_power_off;
 static int restore_id_mux;
+static int charger_idle; /* Spring brick in idle mode */
 
 static int board_rev = 1; /* Assume new boards unless told otherwise */
 
@@ -634,6 +638,23 @@ static int usb_charger_removed(int dev_type)
 	return 0;
 }
 
+static void check_spring_brick_deferred(void)
+{
+	uint8_t id = tsu6721_read(TSU6721_REG_ADC);
+
+	if ((power_removed_type[1] & TSU6721_TYPE_CHG12) &&
+	    (current_dev_type == 0) && (id == 0x17)) {
+		/*
+		 * the power brick is still plugged
+		 * but has internally cut its voltage.
+		 */
+		CPRINTF("[%T Spring brick went to IDLE\n");
+		charger_idle = 1;
+	}
+
+}
+DECLARE_DEFERRED(check_spring_brick_deferred);
+
 /*
  * When a power source is removed, record time, power source type,
  * and PWM duty cycle. Then when we see a power source, compare type
@@ -651,6 +672,15 @@ static void usb_detect_overcurrent(int dev_type)
 		 * retry?
 		 */
 		power_removed_pwm_duty[idx] = current_pwm_duty;
+
+		/*
+		 * if the Spring charger voltage went away,
+		 * check later (after ADC re-sampling time)
+		 * if the ID pin is still there.
+		 */
+		if (current_dev_type & TSU6721_TYPE_CHG12)
+			hook_call_deferred(check_spring_brick_deferred,
+					   ID_REDETECTION_DELAY);
 	} else if (dev_type & TSU6721_TYPE_VBUS_DEBOUNCED) {
 		int idx = !(dev_type == TSU6721_TYPE_VBUS_DEBOUNCED);
 		timestamp_t now = get_time();
@@ -704,6 +734,22 @@ static int usb_manage_boost(int dev_type)
 /* Updates ILIM current limit according to device type. */
 static void usb_update_ilim(int dev_type)
 {
+	if (charger_idle) {
+		/*
+		 * let charger in idle mode until it has been unplugged
+		 * and re-detected.
+		 */
+		if (dev_type == TSU6721_TYPE_VBUS_DEBOUNCED) {
+			charger_idle = 0;
+			CPRINTF("[%T RESET charger idle]\n");
+		} else {
+			/* setting input current to 0 A */
+			board_ilim_config(ILIM_CONFIG_MANUAL_ON);
+			CPRINTF("[%T CHARGER IDLE - ILIM 0A]\n");
+			return;
+		}
+	}
+
 	if (usb_maybe_power_input(dev_type)) {
 		/* Limit USB port current. 500mA for not listed types. */
 		int current_limit = I_LIMIT_500MA;
@@ -974,7 +1020,7 @@ void board_usb_charge_update(int force_update)
 
 int board_get_usb_dev_type(void)
 {
-	return current_dev_type;
+	return charger_idle ? 0 : current_dev_type;
 }
 
 int board_get_usb_current_limit(void)
@@ -991,6 +1037,9 @@ int board_get_ac(void)
 	if (!usb_maybe_power_input(current_dev_type))
 		return 0;
 
+	if (charger_idle)
+		return 0;
+
 	/*
 	 * UVLO is 4.1V. We consider AC bad when its voltage drops below 4.2V
 	 * for two consecutive samples. This is to give PWM a chance to bring