usb: typec: tcpci: Add support to report vSafe0V

This change adds vbus_vsafe0v which when set, makes TCPM
query for VSAFE0V by assigning the tcpc.is_vbus_vsafe0v callback.
Also enables ALERT.ExtendedStatus which is triggered when
status of EXTENDED_STATUS.vSafe0V changes.
EXTENDED_STATUS.vSafe0V is set when vbus is at vSafe0V and
cleared otherwise.
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Acked-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Signed-off-by: Badhri Jagan Sridharan <badhri@google.com>
Link: https://lore.kernel.org/r/20201202040840.663578-2-badhri@google.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/typec/tcpm/tcpci.c

@@ -403,6 +403,19 @@ static int tcpci_get_vbus(struct tcpc_dev *tcpc)
 	return !!(reg & TCPC_POWER_STATUS_VBUS_PRES);
 }
 
+static bool tcpci_is_vbus_vsafe0v(struct tcpc_dev *tcpc)
+{
+	struct tcpci *tcpci = tcpc_to_tcpci(tcpc);
+	unsigned int reg;
+	int ret;
+
+	ret = regmap_read(tcpci->regmap, TCPC_EXTENDED_STATUS, &reg);
+	if (ret < 0)
+		return false;
+
+	return !!(reg & TCPC_EXTENDED_STATUS_VSAFE0V);
+}
+
 static int tcpci_set_vbus(struct tcpc_dev *tcpc, bool source, bool sink)
 {
 	struct tcpci *tcpci = tcpc_to_tcpci(tcpc);
@@ -556,12 +569,22 @@ static int tcpci_init(struct tcpc_dev *tcpc)
 		TCPC_ALERT_RX_HARD_RST | TCPC_ALERT_CC_STATUS;
 	if (tcpci->controls_vbus)
 		reg |= TCPC_ALERT_POWER_STATUS;
+	/* Enable VSAFE0V status interrupt when detecting VSAFE0V is supported */
+	if (tcpci->data->vbus_vsafe0v) {
+		reg |= TCPC_ALERT_EXTENDED_STATUS;
+		ret = regmap_write(tcpci->regmap, TCPC_EXTENDED_STATUS_MASK,
+				   TCPC_EXTENDED_STATUS_VSAFE0V);
+		if (ret < 0)
+			return ret;
+	}
 	return tcpci_write16(tcpci, TCPC_ALERT_MASK, reg);
 }
 
 irqreturn_t tcpci_irq(struct tcpci *tcpci)
 {
 	u16 status;
+	int ret;
+	unsigned int raw;
 
 	tcpci_read16(tcpci, TCPC_ALERT, &status);
 
@@ -577,15 +600,12 @@ irqreturn_t tcpci_irq(struct tcpci *tcpci)
 		tcpm_cc_change(tcpci->port);
 
 	if (status & TCPC_ALERT_POWER_STATUS) {
-		unsigned int reg;
-
-		regmap_read(tcpci->regmap, TCPC_POWER_STATUS_MASK, &reg);
-
+		regmap_read(tcpci->regmap, TCPC_POWER_STATUS_MASK, &raw);
 		/*
 		 * If power status mask has been reset, then the TCPC
 		 * has reset.
 		 */
-		if (reg == 0xff)
+		if (raw == 0xff)
 			tcpm_tcpc_reset(tcpci->port);
 		else
 			tcpm_vbus_change(tcpci->port);
@@ -624,6 +644,12 @@ irqreturn_t tcpci_irq(struct tcpci *tcpci)
 		tcpm_pd_receive(tcpci->port, &msg);
 	}
 
+	if (status & TCPC_ALERT_EXTENDED_STATUS) {
+		ret = regmap_read(tcpci->regmap, TCPC_EXTENDED_STATUS, &raw);
+		if (!ret && (raw & TCPC_EXTENDED_STATUS_VSAFE0V))
+			tcpm_vbus_change(tcpci->port);
+	}
+
 	if (status & TCPC_ALERT_RX_HARD_RST)
 		tcpm_pd_hard_reset(tcpci->port);
 
@@ -701,6 +727,9 @@ struct tcpci *tcpci_register_port(struct device *dev, struct tcpci_data *data)
 			tcpci_set_auto_vbus_discharge_threshold;
 	}
 
+	if (tcpci->data->vbus_vsafe0v)
+		tcpci->tcpc.is_vbus_vsafe0v = tcpci_is_vbus_vsafe0v;
+
 	err = tcpci_parse_config(tcpci);
 	if (err < 0)
 		return ERR_PTR(err);

drivers/usb/typec/tcpm/tcpci.h

@@ -49,6 +49,9 @@
 #define TCPC_TCPC_CTRL_ORIENTATION	BIT(0)
 #define TCPC_TCPC_CTRL_BIST_TM		BIT(1)
 
+#define TCPC_EXTENDED_STATUS		0x20
+#define TCPC_EXTENDED_STATUS_VSAFE0V	BIT(0)
+
 #define TCPC_ROLE_CTRL			0x1a
 #define TCPC_ROLE_CTRL_DRP		BIT(6)
 #define TCPC_ROLE_CTRL_RP_VAL_SHIFT	4
@@ -155,11 +158,14 @@ struct tcpci;
  *		is sourcing vbus.
  * @auto_discharge_disconnect:
  *		Optional; Enables TCPC to autonously discharge vbus on disconnect.
+ * @vbus_vsafe0v:
+ *		optional; Set when TCPC can detect whether vbus is at VSAFE0V.
  */
 struct tcpci_data {
 	struct regmap *regmap;
 	unsigned char TX_BUF_BYTE_x_hidden:1;
 	unsigned char auto_discharge_disconnect:1;
+	unsigned char vbus_vsafe0v:1;
 
 	int (*init)(struct tcpci *tcpci, struct tcpci_data *data);
 	int (*set_vconn)(struct tcpci *tcpci, struct tcpci_data *data,