[PATCH v6 4/7] usb: gadget: udc: renesas_usb3: Add dual role switch support

[Biju Das <biju.das@bp.renesas.com>]

The RZ/G2E cat874 board has a type-c connector connected to hd3ss3220 usb
type-c drp port controller. This patch adds dual role switch support for
the type-c connector using the usb role switch class framework.

Signed-off-by: Biju Das <biju.das@bp.renesas.com>
---
 V5-->V6
   * Added graph api's to find the role supported by the connector.
 V4-->V5
   * Incorporated Shimoda-san's review comment
    (https://patchwork.kernel.org/patch/10902537/)
 V3-->V4
   * No Change
 V2-->V3
   * Incorporated Shimoda-san's review comment
     (https://patchwork.kernel.org/patch/10852507/)
   * Used renesas,usb-role-switch property for differentiating USB
     role switch associated with Type-C port controller driver.
 V1-->V2
   * Driver uses usb role clas for handling dual role switch and handling
     connect/disconnect events instead of extcon.
---
 drivers/usb/gadget/udc/renesas_usb3.c | 121 ++++++++++++++++++++++++++++++++--
 1 file changed, 114 insertions(+), 7 deletions(-)

diff --git a/drivers/usb/gadget/udc/renesas_usb3.c b/drivers/usb/gadget/udc/renesas_usb3.c
index 7dc2485..1d41998 100644
--- a/drivers/usb/gadget/udc/renesas_usb3.c
+++ b/drivers/usb/gadget/udc/renesas_usb3.c
@@ -24,6 +24,7 @@
 #include <linux/usb/ch9.h>
 #include <linux/usb/gadget.h>
 #include <linux/usb/of.h>
+#include <linux/of_graph.h>
 #include <linux/usb/role.h>
 
 /* register definitions */
@@ -351,6 +352,8 @@ struct renesas_usb3 {
 	int disabled_count;
 
 	struct usb_request *ep0_req;
+
+	enum usb_role connection_state;
 	u16 test_mode;
 	u8 ep0_buf[USB3_EP0_BUF_SIZE];
 	bool softconnect;
@@ -359,6 +362,7 @@ struct renesas_usb3 {
 	bool extcon_usb;		/* check vbus and set EXTCON_USB */
 	bool forced_b_device;
 	bool start_to_connect;
+	bool dual_role_sw;
 };
 
 #define gadget_to_renesas_usb3(_gadget)	\
@@ -699,8 +703,10 @@ static void usb3_mode_config(struct renesas_usb3 *usb3, bool host, bool a_dev)
 	unsigned long flags;
 
 	spin_lock_irqsave(&usb3->lock, flags);
-	usb3_set_mode_by_role_sw(usb3, host);
-	usb3_vbus_out(usb3, a_dev);
+	if (!usb3->dual_role_sw || usb3->connection_state != USB_ROLE_NONE) {
+		usb3_set_mode_by_role_sw(usb3, host);
+		usb3_vbus_out(usb3, a_dev);
+	}
 	/* for A-Peripheral or forced B-device mode */
 	if ((!host && a_dev) || usb3->start_to_connect)
 		usb3_connect(usb3);
@@ -716,7 +722,8 @@ static void usb3_check_id(struct renesas_usb3 *usb3)
 {
 	usb3->extcon_host = usb3_is_a_device(usb3);
 
-	if (usb3->extcon_host && !usb3->forced_b_device)
+	if ((!usb3->dual_role_sw && usb3->extcon_host && !usb3->forced_b_device)
+	    || usb3->connection_state == USB_ROLE_HOST)
 		usb3_mode_config(usb3, true, true);
 	else
 		usb3_mode_config(usb3, false, false);
@@ -2343,14 +2350,65 @@ static enum usb_role renesas_usb3_role_switch_get(struct device *dev)
 	return cur_role;
 }
 
-static int renesas_usb3_role_switch_set(struct device *dev,
-					enum usb_role role)
+static void handle_ext_role_switch_states(struct device *dev,
+					    enum usb_role role)
+{
+	struct renesas_usb3 *usb3 = dev_get_drvdata(dev);
+	struct device *host = usb3->host_dev;
+	enum usb_role cur_role = renesas_usb3_role_switch_get(dev);
+
+	switch (role) {
+	case USB_ROLE_NONE:
+		usb3->connection_state = USB_ROLE_NONE;
+		if (usb3->driver)
+			usb3_disconnect(usb3);
+		usb3_vbus_out(usb3, false);
+		break;
+	case USB_ROLE_DEVICE:
+		if (usb3->connection_state == USB_ROLE_NONE) {
+			usb3->connection_state = USB_ROLE_DEVICE;
+			usb3_set_mode(usb3, false);
+			if (usb3->driver)
+				usb3_connect(usb3);
+		} else if (cur_role == USB_ROLE_HOST)  {
+			device_release_driver(host);
+			usb3_set_mode(usb3, false);
+			if (usb3->driver)
+				usb3_connect(usb3);
+		}
+		usb3_vbus_out(usb3, false);
+		break;
+	case USB_ROLE_HOST:
+		if (usb3->connection_state == USB_ROLE_NONE) {
+			if (usb3->driver)
+				usb3_disconnect(usb3);
+
+			usb3->connection_state = USB_ROLE_HOST;
+			usb3_set_mode(usb3, true);
+			usb3_vbus_out(usb3, true);
+			if (device_attach(host) < 0)
+				dev_err(dev, "device_attach(host) failed\n");
+		} else if (cur_role == USB_ROLE_DEVICE) {
+			usb3_disconnect(usb3);
+			/* Must set the mode before device_attach of the host */
+			usb3_set_mode(usb3, true);
+			/* This device_attach() might sleep */
+			if (device_attach(host) < 0)
+				dev_err(dev, "device_attach(host) failed\n");
+		}
+		break;
+	default:
+		break;
+	}
+}
+
+static void handle_role_switch_states(struct device *dev,
+					    enum usb_role role)
 {
 	struct renesas_usb3 *usb3 = dev_get_drvdata(dev);
 	struct device *host = usb3->host_dev;
 	enum usb_role cur_role = renesas_usb3_role_switch_get(dev);
 
-	pm_runtime_get_sync(dev);
 	if (cur_role == USB_ROLE_HOST && role == USB_ROLE_DEVICE) {
 		device_release_driver(host);
 		usb3_set_mode(usb3, false);
@@ -2361,6 +2419,20 @@ static int renesas_usb3_role_switch_set(struct device *dev,
 		if (device_attach(host) < 0)
 			dev_err(dev, "device_attach(host) failed\n");
 	}
+}
+
+static int renesas_usb3_role_switch_set(struct device *dev,
+					enum usb_role role)
+{
+	struct renesas_usb3 *usb3 = dev_get_drvdata(dev);
+
+	pm_runtime_get_sync(dev);
+
+	if (usb3->dual_role_sw)
+		handle_ext_role_switch_states(dev, role);
+	else
+		handle_role_switch_states(dev, role);
+
 	pm_runtime_put(dev);
 
 	return 0;
@@ -2650,12 +2722,41 @@ static const unsigned int renesas_usb3_cable[] = {
 	EXTCON_NONE,
 };
 
-static const struct usb_role_switch_desc renesas_usb3_role_switch_desc = {
+static struct usb_role_switch_desc renesas_usb3_role_switch_desc = {
 	.set = renesas_usb3_role_switch_set,
 	.get = renesas_usb3_role_switch_get,
 	.allow_userspace_control = true,
 };
 
+static bool is_usb_dual_role_switch(struct device *dev)
+{
+	struct device_node *np = dev->of_node;
+	struct device_node *parent;
+	struct device_node *child;
+	bool ret = false;
+	const char *role_type = NULL;
+
+	child = of_graph_get_endpoint_by_regs(np, -1, -1);
+	if (!child)
+		return ret;
+
+	parent = of_graph_get_remote_port_parent(child);
+	of_node_put(child);
+	child = of_get_child_by_name(parent, "connector");
+	of_node_put(parent);
+	if (!child)
+		return ret;
+
+	if (of_device_is_compatible(child, "usb-c-connector")) {
+		of_property_read_string(child, "data-role", &role_type);
+		if (role_type && (!strncmp(role_type, "dual", strlen("dual"))))
+			ret = true;
+	}
+
+	of_node_put(child);
+	return ret;
+}
+
 static int renesas_usb3_probe(struct platform_device *pdev)
 {
 	struct renesas_usb3 *usb3;
@@ -2741,6 +2842,12 @@ static int renesas_usb3_probe(struct platform_device *pdev)
 	if (ret < 0)
 		goto err_dev_create;
 
+	if (device_property_read_bool(&pdev->dev, "usb-role-switch") &&
+	    is_usb_dual_role_switch(&pdev->dev)) {
+		usb3->dual_role_sw = true;
+		renesas_usb3_role_switch_desc.fwnode = dev_fwnode(&pdev->dev);
+	}
+
 	INIT_WORK(&usb3->role_work, renesas_usb3_role_work);
 	usb3->role_sw = usb_role_switch_register(&pdev->dev,
 					&renesas_usb3_role_switch_desc);
-- 
2.7.4