usb: typec: tcpci: Implement callbacks for FRS

Implement tcpc.enable_frs to enable TCPC to receive
Fast role swap signal.

Additionally set the sink disconnect threshold to 4v
to prevent disconnect during Fast Role swap.

Signed-off-by: Badhri Jagan Sridharan <badhri@google.com>
Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Link: https://lore.kernel.org/r/20201008061556.1402293-8-badhri@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/typec/tcpm/tcpci.c

@@ -268,6 +268,22 @@ static int tcpci_set_vconn(struct tcpc_dev *tcpc, bool enable)
 				enable ? TCPC_POWER_CTRL_VCONN_ENABLE : 0);
 }
 
+static int tcpci_enable_frs(struct tcpc_dev *dev, bool enable)
+{
+	struct tcpci *tcpci = tcpc_to_tcpci(dev);
+	int ret;
+
+	/* To prevent disconnect during FRS, set disconnect threshold to 3.5V */
+	ret = tcpci_write16(tcpci, TCPC_VBUS_SINK_DISCONNECT_THRESH, enable ? 0 : 0x8c);
+	if (ret < 0)
+		return ret;
+
+	ret = regmap_update_bits(tcpci->regmap, TCPC_POWER_CTRL, TCPC_FAST_ROLE_SWAP_EN, enable ?
+				 TCPC_FAST_ROLE_SWAP_EN : 0);
+
+	return ret;
+}
+
 static int tcpci_set_bist_data(struct tcpc_dev *tcpc, bool enable)
 {
 	struct tcpci *tcpci = tcpc_to_tcpci(tcpc);
@@ -611,6 +627,7 @@ struct tcpci *tcpci_register_port(struct device *dev, struct tcpci_data *data)
 	tcpci->tcpc.set_roles = tcpci_set_roles;
 	tcpci->tcpc.pd_transmit = tcpci_pd_transmit;
 	tcpci->tcpc.set_bist_data = tcpci_set_bist_data;
+	tcpci->tcpc.enable_frs = tcpci_enable_frs;
 
 	err = tcpci_parse_config(tcpci);
 	if (err < 0)

drivers/usb/typec/tcpm/tcpci.h

@@ -16,6 +16,7 @@
 #define TCPC_PD_INT_REV			0xa
 
 #define TCPC_ALERT			0x10
+#define TCPC_ALERT_EXTND		BIT(14)
 #define TCPC_ALERT_EXTENDED_STATUS	BIT(13)
 #define TCPC_ALERT_VBUS_DISCNCT		BIT(11)
 #define TCPC_ALERT_RX_BUF_OVF		BIT(10)
@@ -37,6 +38,9 @@
 #define TCPC_EXTENDED_STATUS_MASK		0x16
 #define TCPC_EXTENDED_STATUS_MASK_VSAFE0V	BIT(0)
 
+#define TCPC_ALERT_EXTENDED_MASK	0x17
+#define TCPC_SINK_FAST_ROLE_SWAP	BIT(0)
+
 #define TCPC_CONFIG_STD_OUTPUT		0x18
 
 #define TCPC_TCPC_CTRL			0x19
@@ -63,6 +67,7 @@
 
 #define TCPC_POWER_CTRL			0x1c
 #define TCPC_POWER_CTRL_VCONN_ENABLE	BIT(0)
+#define TCPC_FAST_ROLE_SWAP_EN		BIT(7)
 
 #define TCPC_CC_STATUS			0x1d
 #define TCPC_CC_STATUS_TOGGLING		BIT(5)
@@ -74,11 +79,14 @@
 
 #define TCPC_POWER_STATUS		0x1e
 #define TCPC_POWER_STATUS_UNINIT	BIT(6)
+#define TCPC_POWER_STATUS_SOURCING_VBUS	BIT(4)
 #define TCPC_POWER_STATUS_VBUS_DET	BIT(3)
 #define TCPC_POWER_STATUS_VBUS_PRES	BIT(2)
 
 #define TCPC_FAULT_STATUS		0x1f
 
+#define TCPC_ALERT_EXTENDED		0x21
+
 #define TCPC_COMMAND			0x23
 #define TCPC_CMD_WAKE_I2C		0x11
 #define TCPC_CMD_DISABLE_VBUS_DETECT	0x22