usb: typec: tps6598x: Add USB role switching logic

This patch adds USB role switch support to the tps6598x.

The setup to initiate or accept a data-role switch is both assumed and
currently required to be baked-into the firmware as described in TI's
document here.

Link: https://www.ti.com/lit/an/slva843a/slva843a.pdf

With this change its possible to use the USB role-switch API to detect and
notify role-switches to downstream consumers.

Tested with a ChipIdea controller on a Qualcomm MSM8939.

Cc: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Nikolaus Voss <nikolaus.voss@loewensteinmedical.de>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Gustavo A. R. Silva <garsilva@embeddedor.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: linux-usb@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Bryan O'Donoghue <bryan.odonoghue@linaro.org>
Link: https://lore.kernel.org/r/20200511231930.2825183-2-bryan.odonoghue@linaro.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/typec/tps6598x.c

@@ -12,6 +12,7 @@
 #include <linux/regmap.h>
 #include <linux/interrupt.h>
 #include <linux/usb/typec.h>
+#include <linux/usb/role.h>
 
 /* Register offsets */
 #define TPS_REG_VID			0x00
@@ -94,6 +95,7 @@ struct tps6598x {
 	struct typec_port *port;
 	struct typec_partner *partner;
 	struct usb_pd_identity partner_identity;
+	struct usb_role_switch *role_sw;
 };
 
 /*
@@ -190,6 +192,23 @@ static int tps6598x_read_partner_identity(struct tps6598x *tps)
 	return 0;
 }
 
+static void tps6598x_set_data_role(struct tps6598x *tps,
+				   enum typec_data_role role, bool connected)
+{
+	enum usb_role role_val;
+
+	if (role == TYPEC_HOST)
+		role_val = USB_ROLE_HOST;
+	else
+		role_val = USB_ROLE_DEVICE;
+
+	if (!connected)
+		role_val = USB_ROLE_NONE;
+
+	usb_role_switch_set_role(tps->role_sw, role_val);
+	typec_set_data_role(tps->port, role);
+}
+
 static int tps6598x_connect(struct tps6598x *tps, u32 status)
 {
 	struct typec_partner_desc desc;
@@ -220,7 +239,7 @@ static int tps6598x_connect(struct tps6598x *tps, u32 status)
 	typec_set_pwr_opmode(tps->port, mode);
 	typec_set_pwr_role(tps->port, TPS_STATUS_PORTROLE(status));
 	typec_set_vconn_role(tps->port, TPS_STATUS_VCONN(status));
-	typec_set_data_role(tps->port, TPS_STATUS_DATAROLE(status));
+	tps6598x_set_data_role(tps, TPS_STATUS_DATAROLE(status), true);
 
 	tps->partner = typec_register_partner(tps->port, &desc);
 	if (IS_ERR(tps->partner))
@@ -240,7 +259,7 @@ static void tps6598x_disconnect(struct tps6598x *tps, u32 status)
 	typec_set_pwr_opmode(tps->port, TYPEC_PWR_MODE_USB);
 	typec_set_pwr_role(tps->port, TPS_STATUS_PORTROLE(status));
 	typec_set_vconn_role(tps->port, TPS_STATUS_VCONN(status));
-	typec_set_data_role(tps->port, TPS_STATUS_DATAROLE(status));
+	tps6598x_set_data_role(tps, TPS_STATUS_DATAROLE(status), false);
 }
 
 static int tps6598x_exec_cmd(struct tps6598x *tps, const char *cmd,
@@ -328,7 +347,7 @@ static int tps6598x_dr_set(struct typec_port *port, enum typec_data_role role)
 		goto out_unlock;
 	}
 
-	typec_set_data_role(tps->port, role);
+	tps6598x_set_data_role(tps, role, true);
 
 out_unlock:
 	mutex_unlock(&tps->lock);
@@ -452,6 +471,7 @@ static int tps6598x_probe(struct i2c_client *client)
 {
 	struct typec_capability typec_cap = { };
 	struct tps6598x *tps;
+	struct fwnode_handle *fwnode;
 	u32 status;
 	u32 conf;
 	u32 vid;
@@ -495,11 +515,22 @@ static int tps6598x_probe(struct i2c_client *client)
 	if (ret < 0)
 		return ret;
 
+	fwnode = device_get_named_child_node(&client->dev, "connector");
+	if (IS_ERR(fwnode))
+		return PTR_ERR(fwnode);
+
+	tps->role_sw = fwnode_usb_role_switch_get(fwnode);
+	if (IS_ERR(tps->role_sw)) {
+		ret = PTR_ERR(tps->role_sw);
+		goto err_fwnode_put;
+	}
+
 	typec_cap.revision = USB_TYPEC_REV_1_2;
 	typec_cap.pd_revision = 0x200;
 	typec_cap.prefer_role = TYPEC_NO_PREFERRED_ROLE;
 	typec_cap.driver_data = tps;
 	typec_cap.ops = &tps6598x_ops;
+	typec_cap.fwnode = fwnode;
 
 	switch (TPS_SYSCONF_PORTINFO(conf)) {
 	case TPS_PORTINFO_SINK_ACCESSORY:
@@ -525,12 +556,16 @@ static int tps6598x_probe(struct i2c_client *client)
 		typec_cap.data = TYPEC_PORT_DFP;
 		break;
 	default:
-		return -ENODEV;
+		ret = -ENODEV;
+		goto err_role_put;
 	}
 
 	tps->port = typec_register_port(&client->dev, &typec_cap);
-	if (IS_ERR(tps->port))
-		return PTR_ERR(tps->port);
+	if (IS_ERR(tps->port)) {
+		ret = PTR_ERR(tps->port);
+		goto err_role_put;
+	}
+	fwnode_handle_put(fwnode);
 
 	if (status & TPS_STATUS_PLUG_PRESENT) {
 		ret = tps6598x_connect(tps, status);
@@ -545,12 +580,19 @@ static int tps6598x_probe(struct i2c_client *client)
 	if (ret) {
 		tps6598x_disconnect(tps, 0);
 		typec_unregister_port(tps->port);
-		return ret;
+		goto err_role_put;
 	}
 
 	i2c_set_clientdata(client, tps);
 
 	return 0;
+
+err_role_put:
+	usb_role_switch_put(tps->role_sw);
+err_fwnode_put:
+	fwnode_handle_put(fwnode);
+
+	return ret;
 }
 
 static int tps6598x_remove(struct i2c_client *client)
@@ -559,6 +601,7 @@ static int tps6598x_remove(struct i2c_client *client)
 
 	tps6598x_disconnect(tps, 0);
 	typec_unregister_port(tps->port);
+	usb_role_switch_put(tps->role_sw);
 
 	return 0;
 }