u8500-charger: Delay for USB enumeration

If charging is started before USB enumeration of an Accessory
Charger Adapter has finished, the AB8500 will generate a
VBUS_ERROR. This in turn results in timeouts and delays the
enumeration with around 15 seconds. This patch delays the
charging and then ramps currents slowly to avoid VBUS errors.
The delay allows the enumeration to have finished before
charging is turned on.

Signed-off-by: Martin Sjoblom <martin.w.sjoblom@stericsson.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Reviewed-by: Jonas ABERG <jonas.aberg@stericsson.com>
Tested-by: Jonas ABERG <jonas.aberg@stericsson.com>

1 files changed, 325 insertions, 107 deletions

diff --git a/drivers/power/ab8500_charger.c b/drivers/power/ab8500_charger.c
index 432f6bc48764..24b30b7ea5ca 100644
--- a/drivers/power/ab8500_charger.c
+++ b/drivers/power/ab8500_charger.c
@@ -55,6 +55,7 @@
 
 #define MAIN_CH_INPUT_CURR_SHIFT	4
 #define VBUS_IN_CURR_LIM_SHIFT		4
+#define AUTO_VBUS_IN_CURR_LIM_SHIFT	4
 
 #define LED_INDICATOR_PWM_ENA		0x01
 #define LED_INDICATOR_PWM_DIS		0x00
@@ -88,14 +89,13 @@
 /* Step up/down delay in us */
 #define STEP_UDELAY			1000
 
-/* Wait for enumeration before charging in ms */
-#define WAIT_FOR_USB_ENUMERATION	5 * 1000
-
 #define CHARGER_STATUS_POLL 10 /* in ms */
 
 #define CHG_WD_INTERVAL			(60 * HZ)
 
 #define AB8500_SW_CONTROL_FALLBACK	0x03
+/* Wait for enumeration before charing in us */
+#define WAIT_ACA_RID_ENUMERATION	(5 * 1000)
 
 /* UsbLineStatus register - usb types */
 enum ab8500_charger_link_status {
@@ -185,12 +185,14 @@ struct ab8500_charger_event_flags {
 	bool usbchargernotok;
 	bool chgwdexp;
 	bool vbus_collapse;
+	bool vbus_drop_end;
 };
 
 struct ab8500_charger_usb_state {
-	bool usb_changed;
 	int usb_current;
+	int usb_current_tmp;
 	enum ab8500_usb_state state;
+	enum ab8500_usb_state state_tmp;
 	spinlock_t usb_lock;
 };
 
@@ -212,6 +214,10 @@ struct ab8500_charger_usb_state {
  * @autopower		Indicate if we should have automatic pwron after pwrloss
  * @autopower_cfg	platform specific power config support for "pwron after pwrloss"
  * @invalid_charger_detect_state State when forcing AB to use invalid charger
+ * @is_usb_host:	Indicate if last detected USB type is host
+ * @is_aca_rid:		Incicate if accessory is ACA type
+ * @current_stepping_sessions:
+ *			Counter for current stepping sessions
  * @parent:		Pointer to the struct ab8500
  * @gpadc:		Pointer to the struct gpadc
  * @bm:           	Platform specific battery management information
@@ -223,12 +229,13 @@ struct ab8500_charger_usb_state {
  * @usb:		Structure that holds the USB charger properties
  * @regu:		Pointer to the struct regulator
  * @charger_wq:		Work queue for the IRQs and checking HW state
+ * @usb_ipt_crnt_lock:	Lock to protect VBUS input current setting from mutuals
+ * @pm_lock:		Lock to prevent system to suspend
  * @check_vbat_work	Work for checking vbat threshold to adjust vbus current
  * @check_hw_failure_work:	Work for checking HW state
  * @check_usbchgnotok_work:	Work for checking USB charger not ok status
  * @kick_wd_work:		Work for kicking the charger watchdog in case
  *				of ABB rev 1.* due to the watchog logic bug
- * @attach_work:		Work for checking the usb enumeration
  * @ac_charger_attached_work:	Work for checking if AC charger is still
  *				connected
  * @usb_charger_attached_work:	Work for checking if USB charger is still
@@ -237,6 +244,8 @@ struct ab8500_charger_usb_state {
  * @detect_usb_type_work:	Work for detecting the USB type connected
  * @usb_link_status_work:	Work for checking the new USB link status
  * @usb_state_changed_work:	Work for checking USB state
+ * @attach_work:		Work for detecting USB type
+ * @vbus_drop_end_work:		Work for detecting VBUS drop end
  * @check_main_thermal_prot_work:
  *				Work for checking Main thermal status
  * @check_usb_thermal_prot_work:
@@ -257,6 +266,9 @@ struct ab8500_charger {
 	bool autopower;
 	bool autopower_cfg;
 	int invalid_charger_detect_state;
+	bool is_usb_host;
+	int is_aca_rid;
+	atomic_t current_stepping_sessions;
 	struct ab8500 *parent;
 	struct ab8500_gpadc *gpadc;
 	struct abx500_bm_data *bm;
@@ -268,17 +280,19 @@ struct ab8500_charger {
 	struct ab8500_charger_info usb;
 	struct regulator *regu;
 	struct workqueue_struct *charger_wq;
+	struct mutex usb_ipt_crnt_lock;
 	struct delayed_work check_vbat_work;
 	struct delayed_work check_hw_failure_work;
 	struct delayed_work check_usbchgnotok_work;
 	struct delayed_work kick_wd_work;
+	struct delayed_work usb_state_changed_work;
 	struct delayed_work attach_work;
 	struct delayed_work ac_charger_attached_work;
 	struct delayed_work usb_charger_attached_work;
+	struct delayed_work vbus_drop_end_work;
 	struct work_struct ac_work;
 	struct work_struct detect_usb_type_work;
 	struct work_struct usb_link_status_work;
-	struct work_struct usb_state_changed_work;
 	struct work_struct check_main_thermal_prot_work;
 	struct work_struct check_usb_thermal_prot_work;
 	struct usb_phy *usb_phy;
@@ -568,6 +582,7 @@ static int ab8500_charger_usb_cv(struct ab8500_charger *di)
 /**
  * ab8500_charger_detect_chargers() - Detect the connected chargers
  * @di:		pointer to the ab8500_charger structure
+ * @probe:	if probe, don't delay and wait for HW
  *
  * Returns the type of charger connected.
  * For USB it will not mean we can actually charge from it
@@ -581,7 +596,7 @@ static int ab8500_charger_usb_cv(struct ab8500_charger *di)
  * USB_PW_CONN  if the USB power supply is connected
  * AC_PW_CONN + USB_PW_CONN if USB and AC power supplies are both connected
  */
-static int ab8500_charger_detect_chargers(struct ab8500_charger *di)
+static int ab8500_charger_detect_chargers(struct ab8500_charger *di, bool probe)
 {
 	int result = NO_PW_CONN;
 	int ret;
@@ -599,13 +614,25 @@ static int ab8500_charger_detect_chargers(struct ab8500_charger *di)
 		result = AC_PW_CONN;
 
 	/* Check for USB charger */
+
+	if (!probe) {
+		/*
+		 * AB8500 says VBUS_DET_DBNC1 & VBUS_DET_DBNC100
+		 * when disconnecting ACA even though no
+		 * charger was connected. Try waiting a little
+		 * longer than the 100 ms of VBUS_DET_DBNC100...
+		 */
+		msleep(110);
+	}
 	ret = abx500_get_register_interruptible(di->dev, AB8500_CHARGER,
 		AB8500_CH_USBCH_STAT1_REG, &val);
 	if (ret < 0) {
 		dev_err(di->dev, "%s ab8500 read failed\n", __func__);
 		return ret;
 	}
-
+	dev_dbg(di->dev,
+		"%s AB8500_CH_USBCH_STAT1_REG %x\n", __func__,
+		val);
 	if ((val & VBUS_DET_DBNC1) && (val & VBUS_DET_DBNC100))
 		result |= USB_PW_CONN;
 
@@ -628,33 +655,47 @@ static int ab8500_charger_max_usb_curr(struct ab8500_charger *di,
 
 	di->usb_device_is_unrecognised = false;
 
+	/*
+	 * Platform only supports USB 2.0.
+	 * This means that charging current from USB source
+	 * is maximum 500 mA. Every occurence of USB_STAT_*_HOST_*
+	 * should set USB_CH_IP_CUR_LVL_0P5.
+	 */
+
 	switch (link_status) {
 	case USB_STAT_STD_HOST_NC:
 	case USB_STAT_STD_HOST_C_NS:
 	case USB_STAT_STD_HOST_C_S:
 		dev_dbg(di->dev, "USB Type - Standard host is "
-				"detected through USB driver\n");
-		di->max_usb_in_curr = USB_CH_IP_CUR_LVL_0P09;
+			"detected through USB driver\n");
+		di->max_usb_in_curr = USB_CH_IP_CUR_LVL_0P5;
+		di->is_usb_host = true;
+		di->is_aca_rid = 0;
 		break;
 	case USB_STAT_HOST_CHG_HS_CHIRP:
 		di->max_usb_in_curr = USB_CH_IP_CUR_LVL_0P5;
-		dev_dbg(di->dev, "USB Type - 0x%02x MaxCurr: %d", link_status,
-				di->max_usb_in_curr);
+		di->is_usb_host = true;
+		di->is_aca_rid = 0;
 		break;
 	case USB_STAT_HOST_CHG_HS:
+		di->max_usb_in_curr = USB_CH_IP_CUR_LVL_0P5;
+		di->is_usb_host = true;
+		di->is_aca_rid = 0;
+		break;
 	case USB_STAT_ACA_RID_C_HS:
 		di->max_usb_in_curr = USB_CH_IP_CUR_LVL_0P9;
-		dev_dbg(di->dev, "USB Type - 0x%02x MaxCurr: %d", link_status,
-				di->max_usb_in_curr);
+		di->is_usb_host = false;
+		di->is_aca_rid = 0;
 		break;
 	case USB_STAT_ACA_RID_A:
 		/*
 		 * Dedicated charger level minus maximum current accessory
-		 * can consume (300mA). Closest level is 1100mA
+		 * can consume (900mA). Closest level is 500mA
 		 */
-		di->max_usb_in_curr = USB_CH_IP_CUR_LVL_1P1;
-		dev_dbg(di->dev, "USB Type - 0x%02x MaxCurr: %d", link_status,
-				di->max_usb_in_curr);
+		dev_dbg(di->dev, "USB_STAT_ACA_RID_A detected\n");
+		di->max_usb_in_curr = USB_CH_IP_CUR_LVL_0P5;
+		di->is_usb_host = false;
+		di->is_aca_rid = 1;
 		break;
 	case USB_STAT_ACA_RID_B:
 		/*
@@ -664,14 +705,24 @@ static int ab8500_charger_max_usb_curr(struct ab8500_charger *di,
 		di->max_usb_in_curr = USB_CH_IP_CUR_LVL_1P3;
 		dev_dbg(di->dev, "USB Type - 0x%02x MaxCurr: %d", link_status,
 				di->max_usb_in_curr);
+		di->is_usb_host = false;
+		di->is_aca_rid = 1;
 		break;
 	case USB_STAT_HOST_CHG_NM:
+		di->max_usb_in_curr = USB_CH_IP_CUR_LVL_0P5;
+		di->is_usb_host = true;
+		di->is_aca_rid = 0;
+		break;
 	case USB_STAT_DEDICATED_CHG:
-	case USB_STAT_ACA_RID_C_NM:
+		di->max_usb_in_curr = USB_CH_IP_CUR_LVL_1P5;
+		di->is_usb_host = false;
+		di->is_aca_rid = 0;
+		break;
 	case USB_STAT_ACA_RID_C_HS_CHIRP:
+	case USB_STAT_ACA_RID_C_NM:
 		di->max_usb_in_curr = USB_CH_IP_CUR_LVL_1P5;
-		dev_dbg(di->dev, "USB Type - 0x%02x MaxCurr: %d", link_status,
-				di->max_usb_in_curr);
+		di->is_usb_host = false;
+		di->is_aca_rid = 1;
 		break;
 	case USB_STAT_NOT_CONFIGURED:
 		if (di->vbus_detected) {
@@ -788,6 +839,8 @@ static int ab8500_charger_detect_usb_type(struct ab8500_charger *di)
 		ret = abx500_get_register_interruptible(di->dev,
 			AB8500_INTERRUPT, AB8500_IT_SOURCE21_REG,
 			&val);
+		dev_dbg(di->dev, "%s AB8500_IT_SOURCE21_REG %x\n",
+			__func__, val);
 		if (ret < 0) {
 			dev_err(di->dev, "%s ab8500 read failed\n", __func__);
 			return ret;
@@ -803,6 +856,8 @@ static int ab8500_charger_detect_usb_type(struct ab8500_charger *di)
 			dev_err(di->dev, "%s ab8500 read failed\n", __func__);
 			return ret;
 		}
+		dev_dbg(di->dev, "%s AB8500_USB_LINE_STAT_REG %x\n", __func__,
+			val);
 		/*
 		 * Until the IT source register is read the UsbLineStatus
 		 * register is not updated, hence doing the same
@@ -1062,69 +1117,125 @@ static int ab8500_charger_get_usb_cur(struct ab8500_charger *di)
 static int ab8500_charger_set_current(struct ab8500_charger *di,
 	int ich, int reg)
 {
-	int ret, i;
-	int curr_index, prev_curr_index, shift_value;
+	int ret = 0;
+	int auto_curr_index, curr_index, prev_curr_index, shift_value, i;
 	u8 reg_value;
+	u32 step_udelay;
+	bool no_stepping = false;
+
+	atomic_inc(&di->current_stepping_sessions);
+
+	ret = abx500_get_register_interruptible(di->dev, AB8500_CHARGER,
+		reg, &reg_value);
+	if (ret < 0) {
+		dev_err(di->dev, "%s read failed\n", __func__);
+		goto exit_set_current;
+	}
 
 	switch (reg) {
 	case AB8500_MCH_IPT_CURLVL_REG:
 		shift_value = MAIN_CH_INPUT_CURR_SHIFT;
+		prev_curr_index = (reg_value >> shift_value);
 		curr_index = ab8500_current_to_regval(ich);
+		step_udelay = STEP_UDELAY;
+		if (!di->ac.charger_connected)
+			no_stepping = true;
 		break;
 	case AB8500_USBCH_IPT_CRNTLVL_REG:
 		shift_value = VBUS_IN_CURR_LIM_SHIFT;
+		prev_curr_index = (reg_value >> shift_value);
 		curr_index = ab8500_vbus_in_curr_to_regval(ich);
+		step_udelay = STEP_UDELAY * 100;
+
+		ret = abx500_get_register_interruptible(di->dev, AB8500_CHARGER,
+					AB8500_CH_USBCH_STAT2_REG, &reg_value);
+		if (ret < 0) {
+			dev_err(di->dev, "%s read failed\n", __func__);
+			goto exit_set_current;
+		}
+		auto_curr_index =
+			reg_value >> AUTO_VBUS_IN_CURR_LIM_SHIFT;
+
+		dev_dbg(di->dev, "%s Auto VBUS curr is %d mA\n",
+			__func__,
+			ab8500_charger_vbus_in_curr_map[auto_curr_index]);
+
+		prev_curr_index = min(prev_curr_index, auto_curr_index);
+
+		if (!di->usb.charger_connected)
+			no_stepping = true;
 		break;
 	case AB8500_CH_OPT_CRNTLVL_REG:
 		shift_value = 0;
+		prev_curr_index = (reg_value >> shift_value);
 		curr_index = ab8500_current_to_regval(ich);
+		step_udelay = STEP_UDELAY;
+		if (curr_index && (curr_index - prev_curr_index) > 1)
+			step_udelay *= 100;
+
+		if (!di->usb.charger_connected && !di->ac.charger_connected)
+			no_stepping = true;
+
 		break;
 	default:
 		dev_err(di->dev, "%s current register not valid\n", __func__);
-		return -ENXIO;
+		ret = -ENXIO;
+		goto exit_set_current;
 	}
 
 	if (curr_index < 0) {
 		dev_err(di->dev, "requested current limit out-of-range\n");
-		return -ENXIO;
-	}
-
-	ret = abx500_get_register_interruptible(di->dev, AB8500_CHARGER,
-		reg, &reg_value);
-	if (ret < 0) {
-		dev_err(di->dev, "%s read failed\n", __func__);
-		return ret;
+		ret = -ENXIO;
+		goto exit_set_current;
 	}
-	prev_curr_index = (reg_value >> shift_value);
 
 	/* only update current if it's been changed */
-	if (prev_curr_index == curr_index)
-		return 0;
+	if (prev_curr_index == curr_index) {
+		dev_dbg(di->dev, "%s current not changed for reg: 0x%02x\n",
+			__func__, reg);
+		ret = 0;
+		goto exit_set_current;
+	}
 
 	dev_dbg(di->dev, "%s set charger current: %d mA for reg: 0x%02x\n",
 		__func__, ich, reg);
 
-	if (prev_curr_index > curr_index) {
+	if (no_stepping) {
+		ret = abx500_set_register_interruptible(di->dev, AB8500_CHARGER,
+					reg, (u8)curr_index << shift_value);
+		if (ret)
+			dev_err(di->dev, "%s write failed\n", __func__);
+	} else if (prev_curr_index > curr_index) {
 		for (i = prev_curr_index - 1; i >= curr_index; i--) {
+			dev_dbg(di->dev, "curr change_1 to: %x for 0x%02x\n",
+				(u8) i << shift_value, reg);
 			ret = abx500_set_register_interruptible(di->dev,
-				AB8500_CHARGER, reg, (u8) i << shift_value);
+				AB8500_CHARGER, reg, (u8)i << shift_value);
 			if (ret) {
 				dev_err(di->dev, "%s write failed\n", __func__);
-				return ret;
+				goto exit_set_current;
 			}
-			usleep_range(STEP_UDELAY, STEP_UDELAY * 2);
+			if (i != curr_index)
+				usleep_range(step_udelay, step_udelay * 2);
 		}
 	} else {
 		for (i = prev_curr_index + 1; i <= curr_index; i++) {
+			dev_dbg(di->dev, "curr change_2 to: %x for 0x%02x\n",
+				(u8)i << shift_value, reg);
 			ret = abx500_set_register_interruptible(di->dev,
-				AB8500_CHARGER, reg, (u8) i << shift_value);
+				AB8500_CHARGER, reg, (u8)i << shift_value);
 			if (ret) {
 				dev_err(di->dev, "%s write failed\n", __func__);
-				return ret;
+				goto exit_set_current;
 			}
-			usleep_range(STEP_UDELAY, STEP_UDELAY * 2);
+			if (i != curr_index)
+				usleep_range(step_udelay, step_udelay * 2);
 		}
 	}
+
+exit_set_current:
+	atomic_dec(&di->current_stepping_sessions);
+
 	return ret;
 }
 
@@ -1140,6 +1251,7 @@ static int ab8500_charger_set_vbus_in_curr(struct ab8500_charger *di,
 		int ich_in)
 {
 	int min_value;
+	int ret;
 
 	/* We should always use to lowest current limit */
 	min_value = min(di->bm->chg_params->usb_curr_max, ich_in);
@@ -1157,8 +1269,14 @@ static int ab8500_charger_set_vbus_in_curr(struct ab8500_charger *di,
 		break;
 	}
 
-	return ab8500_charger_set_current(di, min_value,
+	dev_info(di->dev, "VBUS input current limit set to %d mA\n", min_value);
+
+	mutex_lock(&di->usb_ipt_crnt_lock);
+	ret = ab8500_charger_set_current(di, min_value,
 		AB8500_USBCH_IPT_CRNTLVL_REG);
+	mutex_unlock(&di->usb_ipt_crnt_lock);
+
+	return ret;
 }
 
 /**
@@ -1469,25 +1587,13 @@ static int ab8500_charger_usb_en(struct ux500_charger *charger,
 			dev_err(di->dev, "%s write failed\n", __func__);
 			return ret;
 		}
-		/* USBChInputCurr: current that can be drawn from the usb */
-		ret = ab8500_charger_set_vbus_in_curr(di, di->max_usb_in_curr);
-		if (ret) {
-			dev_err(di->dev, "setting USBChInputCurr failed\n");
-			return ret;
-		}
-		/* ChOutputCurentLevel: protected output current */
-		ret = ab8500_charger_set_output_curr(di, ich_out);
-		if (ret) {
-			dev_err(di->dev, "%s "
-				"Failed to set ChOutputCurentLevel\n",
-				__func__);
-			return ret;
-		}
 		/* Check if VBAT overshoot control should be enabled */
 		if (!di->bm->enable_overshoot)
 			overshoot = USB_CHG_NO_OVERSHOOT_ENA_N;
 
 		/* Enable USB Charger */
+		dev_dbg(di->dev,
+			"Enabling USB with write to AB8500_USBCH_CTRL1_REG\n");
 		ret = abx500_set_register_interruptible(di->dev, AB8500_CHARGER,
 			AB8500_USBCH_CTRL1_REG, USB_CH_ENA | overshoot);
 		if (ret) {
@@ -1500,11 +1606,29 @@ static int ab8500_charger_usb_en(struct ux500_charger *charger,
 		if (ret < 0)
 			dev_err(di->dev, "failed to enable LED\n");
 
+		di->usb.charger_online = 1;
+
+		/* USBChInputCurr: current that can be drawn from the usb */
+		ret = ab8500_charger_set_vbus_in_curr(di, di->max_usb_in_curr);
+		if (ret) {
+			dev_err(di->dev, "setting USBChInputCurr failed\n");
+			return ret;
+		}
+
+		/* ChOutputCurentLevel: protected output current */
+		ret = ab8500_charger_set_output_curr(di, ich_out);
+		if (ret) {
+			dev_err(di->dev, "%s "
+				"Failed to set ChOutputCurentLevel\n",
+				__func__);
+			return ret;
+		}
+
 		queue_delayed_work(di->charger_wq, &di->check_vbat_work, HZ);
 
-		di->usb.charger_online = 1;
 	} else {
 		/* Disable USB charging */
+		dev_dbg(di->dev, "%s Disabled USB charging\n", __func__);
 		ret = abx500_set_register_interruptible(di->dev,
 			AB8500_CHARGER,
 			AB8500_USBCH_CTRL1_REG, 0);
@@ -1517,7 +1641,21 @@ static int ab8500_charger_usb_en(struct ux500_charger *charger,
 		ret = ab8500_charger_led_en(di, false);
 		if (ret < 0)
 			dev_err(di->dev, "failed to disable LED\n");
+		/* USBChInputCurr: current that can be drawn from the usb */
+		ret = ab8500_charger_set_vbus_in_curr(di, 0);
+		if (ret) {
+			dev_err(di->dev, "setting USBChInputCurr failed\n");
+			return ret;
+		}
 
+		/* ChOutputCurentLevel: protected output current */
+		ret = ab8500_charger_set_output_curr(di, 0);
+		if (ret) {
+			dev_err(di->dev, "%s "
+				"Failed to reset ChOutputCurentLevel\n",
+				__func__);
+			return ret;
+		}
 		di->usb.charger_online = 0;
 		di->usb.wd_expired = false;
 
@@ -1800,7 +1938,7 @@ static void ab8500_charger_ac_work(struct work_struct *work)
 	 * synchronously, we have the check if the main charger is
 	 * connected by reading the status register
 	 */
-	ret = ab8500_charger_detect_chargers(di);
+	ret = ab8500_charger_detect_chargers(di, false);
 	if (ret < 0)
 		return;
 
@@ -1911,16 +2049,18 @@ static void ab8500_charger_detect_usb_type_work(struct work_struct *work)
 	 * synchronously, we have the check if is
 	 * connected by reading the status register
 	 */
-	ret = ab8500_charger_detect_chargers(di);
+	ret = ab8500_charger_detect_chargers(di, false);
 	if (ret < 0)
 		return;
 
 	if (!(ret & USB_PW_CONN)) {
-		di->vbus_detected = 0;
+		dev_dbg(di->dev, "%s di->vbus_detected = false\n", __func__);
+		di->vbus_detected = false;
 		ab8500_charger_set_usb_connected(di, false);
 		ab8500_power_supply_changed(di, &di->usb_chg.psy);
 	} else {
-		di->vbus_detected = 1;
+		dev_dbg(di->dev, "%s di->vbus_detected = true\n", __func__);
+		di->vbus_detected = true;
 
 		if (is_ab8500_1p1_or_earlier(di->parent)) {
 			ret = ab8500_charger_detect_usb_type(di);
@@ -1930,7 +2070,8 @@ static void ab8500_charger_detect_usb_type_work(struct work_struct *work)
 							    &di->usb_chg.psy);
 			}
 		} else {
-			/* For ABB cut2.0 and onwards we have an IRQ,
+			/*
+			 * For ABB cut2.0 and onwards we have an IRQ,
 			 * USB_LINK_STATUS that will be triggered when the USB
 			 * link status changes. The exception is USB connected
 			 * during startup. Then we don't get a
@@ -1951,7 +2092,7 @@ static void ab8500_charger_detect_usb_type_work(struct work_struct *work)
 }
 
 /**
- * ab8500_charger_usb_link_attach_work() - delayd work to detect USB type
+ * ab8500_charger_usb_link_attach_work() - work to detect USB type
  * @work:	pointer to the work_struct structure
  *
  * Detect the type of USB plugged
@@ -1993,7 +2134,7 @@ static void ab8500_charger_usb_link_status_work(struct work_struct *work)
 	 * synchronously, we have the check if  is
 	 * connected by reading the status register
 	 */
-	detected_chargers = ab8500_charger_detect_chargers(di);
+	detected_chargers = ab8500_charger_detect_chargers(di, false);
 	if (detected_chargers < 0)
 		return;
 
@@ -2042,32 +2183,46 @@ static void ab8500_charger_usb_link_status_work(struct work_struct *work)
 	}
 
 	if (!(detected_chargers & USB_PW_CONN)) {
-		di->vbus_detected = 0;
+		di->vbus_detected = false;
 		ab8500_charger_set_usb_connected(di, false);
 		ab8500_power_supply_changed(di, &di->usb_chg.psy);
 		return;
 	}
 
-	di->vbus_detected = 1;
+	dev_dbg(di->dev,"%s di->vbus_detected = true\n",__func__);
+	di->vbus_detected = true;
 	ret = ab8500_charger_read_usb_type(di);
-	if (!ret) {
-		if (di->usb_device_is_unrecognised) {
-			dev_dbg(di->dev,
-				"Potential Legacy Charger device. "
-				"Delay work for %d msec for USB enum "
-				"to finish",
-				WAIT_FOR_USB_ENUMERATION);
-			queue_delayed_work(di->charger_wq,
-					   &di->attach_work,
-					   msecs_to_jiffies(WAIT_FOR_USB_ENUMERATION));
-		} else {
-			queue_delayed_work(di->charger_wq,
-					   &di->attach_work, 0);
+	if (ret) {
+		if (ret == -ENXIO) {
+			/* No valid charger type detected */
+			ab8500_charger_set_usb_connected(di, false);
+			ab8500_power_supply_changed(di, &di->usb_chg.psy);
 		}
-	} else if (ret == -ENXIO) {
-		/* No valid charger type detected */
-		ab8500_charger_set_usb_connected(di, false);
-		ab8500_power_supply_changed(di, &di->usb_chg.psy);
+		return;
+	}
+
+	if (di->usb_device_is_unrecognised) {
+		dev_dbg(di->dev,
+			"Potential Legacy Charger device. "
+			"Delay work for %d msec for USB enum "
+			"to finish",
+			WAIT_ACA_RID_ENUMERATION);
+		queue_delayed_work(di->charger_wq,
+				   &di->attach_work,
+				   msecs_to_jiffies(WAIT_ACA_RID_ENUMERATION));
+	} else if (di->is_aca_rid == 1) {
+		/* Only wait once */
+		di->is_aca_rid++;
+		dev_dbg(di->dev,
+			"%s Wait %d msec for USB enum to finish",
+			__func__, WAIT_ACA_RID_ENUMERATION);
+		queue_delayed_work(di->charger_wq,
+				   &di->attach_work,
+				   msecs_to_jiffies(WAIT_ACA_RID_ENUMERATION));
+	} else {
+		queue_delayed_work(di->charger_wq,
+				   &di->attach_work,
+				   0);
 	}
 }
 
@@ -2077,24 +2232,20 @@ static void ab8500_charger_usb_state_changed_work(struct work_struct *work)
 	unsigned long flags;
 
 	struct ab8500_charger *di = container_of(work,
-		struct ab8500_charger, usb_state_changed_work);
+		struct ab8500_charger, usb_state_changed_work.work);
 
-	if (!di->vbus_detected)
+	if (!di->vbus_detected)	{
+		dev_dbg(di->dev,
+			"%s !di->vbus_detected\n",
+			__func__);
 		return;
+	}
 
 	spin_lock_irqsave(&di->usb_state.usb_lock, flags);
-	di->usb_state.usb_changed = false;
+	di->usb_state.state = di->usb_state.state_tmp;
+	di->usb_state.usb_current = di->usb_state.usb_current_tmp;
 	spin_unlock_irqrestore(&di->usb_state.usb_lock, flags);
 
-	/*
-	 * wait for some time until you get updates from the usb stack
-	 * and negotiations are completed
-	 */
-	msleep(250);
-
-	if (di->usb_state.usb_changed)
-		return;
-
 	dev_dbg(di->dev, "%s USB state: 0x%02x mA: %d\n",
 		__func__, di->usb_state.state, di->usb_state.usb_current);
 
@@ -2336,6 +2487,21 @@ static irqreturn_t ab8500_charger_mainchthprotf_handler(int irq, void *_di)
 	return IRQ_HANDLED;
 }
 
+static void ab8500_charger_vbus_drop_end_work(struct work_struct *work)
+{
+	struct ab8500_charger *di = container_of(work,
+		struct ab8500_charger, vbus_drop_end_work.work);
+
+	di->flags.vbus_drop_end = false;
+
+	/* Reset the drop counter */
+	abx500_set_register_interruptible(di->dev,
+				  AB8500_CHARGER, AB8500_CHARGER_CTRL, 0x01);
+
+	if (di->usb.charger_connected)
+		ab8500_charger_set_vbus_in_curr(di, di->max_usb_in_curr);
+}
+
 /**
  * ab8500_charger_vbusdetf_handler() - VBUS falling detected
  * @irq:       interrupt number
@@ -2347,6 +2513,7 @@ static irqreturn_t ab8500_charger_vbusdetf_handler(int irq, void *_di)
 {
 	struct ab8500_charger *di = _di;
 
+	di->vbus_detected = false;
 	dev_dbg(di->dev, "VBUS falling detected\n");
 	queue_work(di->charger_wq, &di->detect_usb_type_work);
 
@@ -2366,6 +2533,7 @@ static irqreturn_t ab8500_charger_vbusdetr_handler(int irq, void *_di)
 
 	di->vbus_detected = true;
 	dev_dbg(di->dev, "VBUS rising detected\n");
+
 	queue_work(di->charger_wq, &di->detect_usb_type_work);
 
 	return IRQ_HANDLED;
@@ -2474,6 +2642,25 @@ static irqreturn_t ab8500_charger_chwdexp_handler(int irq, void *_di)
 }
 
 /**
+ * ab8500_charger_vbuschdropend_handler() - VBUS drop removed
+ * @irq:       interrupt number
+ * @_di:       pointer to the ab8500_charger structure
+ *
+ * Returns IRQ status(IRQ_HANDLED)
+ */
+static irqreturn_t ab8500_charger_vbuschdropend_handler(int irq, void *_di)
+{
+	struct ab8500_charger *di = _di;
+
+	dev_dbg(di->dev, "VBUS charger drop ended\n");
+	di->flags.vbus_drop_end = true;
+	queue_delayed_work(di->charger_wq, &di->vbus_drop_end_work,
+			   round_jiffies(30 * HZ));
+
+	return IRQ_HANDLED;
+}
+
+/**
  * ab8500_charger_vbusovv_handler() - VBUS overvoltage detected
  * @irq:       interrupt number
  * @_di:       pointer to the ab8500_charger structure
@@ -2743,6 +2930,20 @@ static int ab8500_charger_init_hw_registers(struct ab8500_charger *di)
 		goto out;
 	}
 
+	/* Set charger watchdog timeout */
+	ret = abx500_set_register_interruptible(di->dev, AB8500_CHARGER,
+		AB8500_CH_WD_TIMER_REG, WD_TIMER);
+	if (ret) {
+		dev_err(di->dev, "failed to set charger watchdog timeout\n");
+		goto out;
+	}
+
+	ret = ab8500_charger_led_en(di, false);
+	if (ret < 0) {
+		dev_err(di->dev, "failed to disable LED\n");
+		goto out;
+	}
+
 	/* Backup battery voltage and current */
 	ret = abx500_set_register_interruptible(di->dev,
 		AB8500_RTC,
@@ -2782,6 +2983,7 @@ static struct ab8500_charger_interrupts ab8500_charger_irq[] = {
 	{"USB_CHARGER_NOT_OKR", ab8500_charger_usbchargernotokr_handler},
 	{"VBUS_OVV", ab8500_charger_vbusovv_handler},
 	{"CH_WD_EXP", ab8500_charger_chwdexp_handler},
+	{"VBUS_CH_DROP_END", ab8500_charger_vbuschdropend_handler},
 };
 
 static int ab8500_charger_usb_notifier_call(struct notifier_block *nb,
@@ -2818,13 +3020,15 @@ static int ab8500_charger_usb_notifier_call(struct notifier_block *nb,
 		__func__, bm_usb_state, mA);
 
 	spin_lock(&di->usb_state.usb_lock);
-	di->usb_state.usb_changed = true;
+	di->usb_state.state_tmp = bm_usb_state;
+	di->usb_state.usb_current_tmp = mA;
 	spin_unlock(&di->usb_state.usb_lock);
 
-	di->usb_state.state = bm_usb_state;
-	di->usb_state.usb_current = mA;
-
-	queue_work(di->charger_wq, &di->usb_state_changed_work);
+	/*
+	 * wait for some time until you get updates from the usb stack
+	 * and negotiations are completed
+	 */
+	queue_delayed_work(di->charger_wq, &di->usb_state_changed_work, HZ/2);
 
 	return NOTIFY_OK;
 }
@@ -2864,6 +3068,9 @@ static int ab8500_charger_resume(struct platform_device *pdev)
 			&di->check_hw_failure_work, 0);
 	}
 
+	if (di->flags.vbus_drop_end)
+		queue_delayed_work(di->charger_wq, &di->vbus_drop_end_work, 0);
+
 	return 0;
 }
 
@@ -2876,6 +3083,9 @@ static int ab8500_charger_suspend(struct platform_device *pdev,
 	if (delayed_work_pending(&di->check_hw_failure_work))
 		cancel_delayed_work(&di->check_hw_failure_work);
 
+	if (delayed_work_pending(&di->vbus_drop_end_work))
+		cancel_delayed_work(&di->vbus_drop_end_work);
+
 	flush_delayed_work(&di->attach_work);
 	flush_delayed_work(&di->usb_charger_attached_work);
 	flush_delayed_work(&di->ac_charger_attached_work);
@@ -2887,6 +3097,9 @@ static int ab8500_charger_suspend(struct platform_device *pdev,
 	flush_work(&di->ac_work);
 	flush_work(&di->detect_usb_type_work);
 
+	if (atomic_read(&di->current_stepping_sessions))
+		return -EAGAIN;
+
 	return 0;
 }
 #else
@@ -2926,9 +3139,10 @@ static int ab8500_charger_remove(struct platform_device *pdev)
 	flush_scheduled_work();
 	if(di->usb_chg.enabled)
 		power_supply_unregister(&di->usb_chg.psy);
+#if !defined(CONFIG_CHARGER_PM2301)
 	if(di->ac_chg.enabled)
 		power_supply_unregister(&di->ac_chg.psy);
-
+#endif
 	platform_set_drvdata(pdev, NULL);
 
 	return 0;
@@ -2976,6 +3190,7 @@ static int ab8500_charger_probe(struct platform_device *pdev)
 
 	/* initialize lock */
 	spin_lock_init(&di->usb_state.usb_lock);
+	mutex_init(&di->usb_ipt_crnt_lock);
 
 	di->autopower = false;
 	di->invalid_charger_detect_state = 0;
@@ -3061,6 +3276,12 @@ static int ab8500_charger_probe(struct platform_device *pdev)
 	INIT_DELAYED_WORK(&di->attach_work,
 		ab8500_charger_usb_link_attach_work);
 
+	INIT_DELAYED_WORK(&di->usb_state_changed_work,
+		ab8500_charger_usb_state_changed_work);
+
+	INIT_DELAYED_WORK(&di->vbus_drop_end_work,
+		ab8500_charger_vbus_drop_end_work);
+
 	/* Init work for charger detection */
 	INIT_WORK(&di->usb_link_status_work,
 		ab8500_charger_usb_link_status_work);
@@ -3068,9 +3289,6 @@ static int ab8500_charger_probe(struct platform_device *pdev)
 	INIT_WORK(&di->detect_usb_type_work,
 		ab8500_charger_detect_usb_type_work);
 
-	INIT_WORK(&di->usb_state_changed_work,
-		ab8500_charger_usb_state_changed_work);
-
 	/* Init work for checking HW status */
 	INIT_WORK(&di->check_main_thermal_prot_work,
 		ab8500_charger_check_main_thermal_prot_work);
@@ -3129,7 +3347,7 @@ static int ab8500_charger_probe(struct platform_device *pdev)
 	}
 
 	/* Identify the connected charger types during startup */
-	charger_status = ab8500_charger_detect_chargers(di);
+	charger_status = ab8500_charger_detect_chargers(di, true);
 	if (charger_status & AC_PW_CONN) {
 		di->ac.charger_connected = 1;
 		di->ac_conn = true;
@@ -3164,7 +3382,7 @@ static int ab8500_charger_probe(struct platform_device *pdev)
 
 	mutex_lock(&di->charger_attached_mutex);
 
-	ch_stat = ab8500_charger_detect_chargers(di);
+	ch_stat = ab8500_charger_detect_chargers(di, false);
 
 	if ((ch_stat & AC_PW_CONN) == AC_PW_CONN) {
 		queue_delayed_work(di->charger_wq,