The OTG state machine needs a mechanism to start and
stop the gadget controller as well as connect/disconnect
from the bus. Add usb_gadget_start(), usb_gadget_stop()
and usb_gadget_connect_control().

Introduce usb_otg_add_gadget_udc() to allow controller drivers
to register a gadget controller that is part of an OTG instance.

Register with OTG core when UDC is added in usb_add_gadget_udc_release()
and unregister on usb_del_gadget_udc().

Notify the OTG core when gadget function driver is available on
udc_bind_to_driver() and when it is removed in usb_gadget_remove_driver().

We need to unlock the usb_lock mutex before calling
usb_otg_register_gadget() else it will cause a circular
locking dependency.

Ignore softconnect sysfs control when we're in OTG
mode as OTG FSM should care of gadget softconnect using
the b_bus_req mechanism.

Signed-off-by: Roger Quadros <rog...@ti.com>
---
v11:
- removed left over -EPROBE_DEFER in udc_bind_to_driver().

 drivers/usb/gadget/udc/core.c | 202 +++++++++++++++++++++++++++++++++++++++---
 include/linux/usb/gadget.h    |   4 +
 2 files changed, 196 insertions(+), 10 deletions(-)

diff --git a/drivers/usb/gadget/udc/core.c b/drivers/usb/gadget/udc/core.c
index 42756d7..1290f03 100644
--- a/drivers/usb/gadget/udc/core.c
+++ b/drivers/usb/gadget/udc/core.c
@@ -28,6 +28,11 @@
 #include <linux/usb/ch9.h>
 #include <linux/usb/gadget.h>
 #include <linux/usb.h>
+#include <linux/usb/otg.h>
+#include <linux/usb/of.h>
+
+#include <linux/of.h>
+#include <linux/of_platform.h>
 
 #include "trace.h"
 
@@ -1060,6 +1065,113 @@ static inline void usb_gadget_udc_stop(struct usb_udc 
*udc)
 }
 
 /**
+ * usb_gadget_to_udc - get the UDC owning the gadget
+ *
+ * udc_lock must be held.
+ * Returs NULL if UDC is not found.
+ */
+static struct usb_udc *usb_gadget_to_udc(struct usb_gadget *gadget)
+{
+       struct usb_udc *udc;
+
+       list_for_each_entry(udc, &udc_list, list)
+               if (udc->gadget == gadget)
+                       return udc;
+
+       return NULL;
+}
+
+/**
+ * usb_gadget_start - start the usb gadget controller
+ * @gadget: the gadget device to start
+ *
+ * This is external API for use by OTG core.
+ *
+ * Start the usb device controller. Does not connect to the bus.
+ */
+static int usb_gadget_start(struct usb_gadget *gadget)
+{
+       int ret;
+       struct usb_udc *udc;
+
+       mutex_lock(&udc_lock);
+       udc = usb_gadget_to_udc(gadget);
+       if (!udc) {
+               dev_err(gadget->dev.parent, "%s: gadget not registered.\n",
+                       __func__);
+               mutex_unlock(&udc_lock);
+               return -EINVAL;
+       }
+
+       ret = usb_gadget_udc_start(udc);
+       if (ret)
+               dev_err(&udc->dev, "USB Device Controller didn't start: %d\n",
+                       ret);
+
+       mutex_unlock(&udc_lock);
+
+       return ret;
+}
+
+/**
+ * usb_gadget_stop - stop the usb gadget controller
+ * @gadget: the gadget device we want to stop
+ *
+ * This is external API for use by OTG core.
+ *
+ * Stop the gadget controller. Does not disconnect from the bus.
+ * Caller must ensure that gadget has disconnected from the bus
+ * before calling usb_gadget_stop().
+ */
+static int usb_gadget_stop(struct usb_gadget *gadget)
+{
+       struct usb_udc *udc;
+
+       mutex_lock(&udc_lock);
+       udc = usb_gadget_to_udc(gadget);
+       if (!udc) {
+               dev_err(gadget->dev.parent, "%s: gadget not registered.\n",
+                       __func__);
+               mutex_unlock(&udc_lock);
+               return -EINVAL;
+       }
+
+       if (gadget->connected)
+               dev_dbg(gadget->dev.parent,
+                       "%s: called while still connected\n", __func__);
+
+       usb_gadget_udc_stop(udc);
+       mutex_unlock(&udc_lock);
+
+       return 0;
+}
+
+static int usb_gadget_connect_control(struct usb_gadget *gadget, bool connect)
+{
+       struct usb_udc *udc;
+
+       mutex_lock(&udc_lock);
+       udc = usb_gadget_to_udc(gadget);
+       if (!udc) {
+               dev_err(gadget->dev.parent, "%s: gadget not registered.\n",
+                       __func__);
+               mutex_unlock(&udc_lock);
+               return -EINVAL;
+       }
+
+       if (connect) {
+               usb_gadget_connect(udc->gadget);
+       } else {
+               usb_gadget_disconnect(udc->gadget);
+               udc->driver->disconnect(udc->gadget);
+       }
+
+       mutex_unlock(&udc_lock);
+
+       return 0;
+}
+
+/**
  * usb_udc_release - release the usb_udc struct
  * @dev: the dev member within usb_udc
  *
@@ -1082,6 +1194,12 @@ static void usb_udc_nop_release(struct device *dev)
        dev_vdbg(dev, "%s\n", __func__);
 }
 
+struct otg_gadget_ops otg_gadget_intf = {
+       .start = usb_gadget_start,
+       .stop = usb_gadget_stop,
+       .connect_control = usb_gadget_connect_control,
+};
+
 /**
  * usb_add_gadget_udc_release - adds a new gadget to the udc class driver list
  * @parent: the parent device to this udc. Usually the controller driver's
@@ -1137,6 +1255,14 @@ int usb_add_gadget_udc_release(struct device *parent, 
struct usb_gadget *gadget,
        usb_gadget_set_state(gadget, USB_STATE_NOTATTACHED);
        udc->vbus = true;
 
+       if (gadget->otg_dev) {
+               mutex_unlock(&udc_lock);
+               ret = usb_otg_register_gadget(gadget, &otg_gadget_intf);
+               mutex_lock(&udc_lock);
+               if (ret)
+                       goto err5;
+       }
+
        /* pick up one of pending gadget drivers */
        list_for_each_entry(driver, &gadget_driver_pending_list, pending) {
                if (!driver->udc_name || strcmp(driver->udc_name,
@@ -1145,7 +1271,7 @@ int usb_add_gadget_udc_release(struct device *parent, 
struct usb_gadget *gadget,
                        if (ret != -EPROBE_DEFER)
                                list_del(&driver->pending);
                        if (ret)
-                               goto err4;
+                               goto err5;
                        break;
                }
        }
@@ -1154,6 +1280,8 @@ int usb_add_gadget_udc_release(struct device *parent, 
struct usb_gadget *gadget,
 
        return 0;
 
+err5:
+       device_del(&udc->dev);
 err4:
        list_del(&udc->list);
        mutex_unlock(&udc_lock);
@@ -1215,6 +1343,33 @@ int usb_add_gadget_udc(struct device *parent, struct 
usb_gadget *gadget)
 }
 EXPORT_SYMBOL_GPL(usb_add_gadget_udc);
 
+/**
+ * usb_otg_add_gadget_udc - adds a new gadget to the udc class driver list
+ * @parent: the parent device to the UDC. Usually the Gadget controller
+ * driver's device.
+ * @gadget: the gadget to be added to the list
+ * @otg_dev: the OTG controller device
+ *
+ * If otg_dev is NULL then device tree node is checked
+ * for OTG controller via the otg-controller property.
+ * Returns zero on success, negative errno otherwise.
+ */
+int usb_otg_add_gadget_udc(struct device *parent, struct usb_gadget *gadget,
+                          struct device *otg_dev)
+{
+       if (!otg_dev) {
+               gadget->otg_dev = of_usb_get_otg(parent->of_node);
+               if (!gadget->otg_dev)
+                       return -ENODEV;
+       } else {
+               gadget->otg_dev = otg_dev;
+       }
+
+       return usb_add_gadget_udc_release(parent, gadget, NULL);
+}
+EXPORT_SYMBOL_GPL(usb_otg_add_gadget_udc);
+
+/* udc_lock must be held */
 static void usb_gadget_remove_driver(struct usb_udc *udc)
 {
        dev_dbg(&udc->dev, "unregistering UDC driver [%s]\n",
@@ -1222,10 +1377,18 @@ static void usb_gadget_remove_driver(struct usb_udc 
*udc)
 
        kobject_uevent(&udc->dev.kobj, KOBJ_CHANGE);
 
-       usb_gadget_disconnect(udc->gadget);
-       udc->driver->disconnect(udc->gadget);
+       /* If OTG/dual-role, the otg core manages UDC start/stop */
+       if (udc->gadget->otg_dev) {
+               mutex_unlock(&udc_lock);
+               usb_otg_gadget_ready(udc->gadget, false);
+               mutex_lock(&udc_lock);
+       } else {
+               usb_gadget_disconnect(udc->gadget);
+               udc->driver->disconnect(udc->gadget);
+               usb_gadget_udc_stop(udc);
+       }
+
        udc->driver->unbind(udc->gadget);
-       usb_gadget_udc_stop(udc);
 
        udc->driver = NULL;
        udc->dev.driver = NULL;
@@ -1259,6 +1422,9 @@ void usb_del_gadget_udc(struct usb_gadget *gadget)
        }
        mutex_unlock(&udc_lock);
 
+       if (gadget->otg_dev)
+               usb_otg_unregister_gadget(gadget);
+
        kobject_uevent(&udc->dev.kobj, KOBJ_REMOVE);
        flush_work(&gadget->work);
        device_unregister(&udc->dev);
@@ -1268,6 +1434,7 @@ EXPORT_SYMBOL_GPL(usb_del_gadget_udc);
 
 /* ------------------------------------------------------------------------- */
 
+/* udc_lock must be held */
 static int udc_bind_to_driver(struct usb_udc *udc, struct usb_gadget_driver 
*driver)
 {
        int ret;
@@ -1282,17 +1449,26 @@ static int udc_bind_to_driver(struct usb_udc *udc, 
struct usb_gadget_driver *dri
        ret = driver->bind(udc->gadget, driver);
        if (ret)
                goto err1;
-       ret = usb_gadget_udc_start(udc);
-       if (ret) {
-               driver->unbind(udc->gadget);
-               goto err1;
+
+       /* If OTG/dual-role, the otg core manages UDC start/stop */
+       if (udc->gadget->otg_dev) {
+               mutex_unlock(&udc_lock);
+               usb_otg_gadget_ready(udc->gadget, true);
+               mutex_lock(&udc_lock);
+       } else {
+               ret = usb_gadget_udc_start(udc);
+               if (ret) {
+                       mutex_unlock(&udc_lock);
+                       driver->unbind(udc->gadget);
+                       goto err1;
+               }
+               usb_udc_connect_control(udc);
        }
-       usb_udc_connect_control(udc);
 
        kobject_uevent(&udc->dev.kobj, KOBJ_CHANGE);
        return 0;
 err1:
-       if (ret != -EISNAM)
+       if ((ret != -EISNAM))
                dev_err(&udc->dev, "failed to start %s: %d\n",
                        udc->driver->function, ret);
        udc->driver = NULL;
@@ -1389,6 +1565,12 @@ static ssize_t usb_udc_softconn_store(struct device *dev,
                return -EOPNOTSUPP;
        }
 
+       /* In OTG/dual-role mode, soft-connect should be handled by OTG core */
+       if (udc->gadget->otg_dev) {
+               dev_err(dev, "soft-connect not supported in OTG mode\n");
+               return -EOPNOTSUPP;
+       }
+
        if (sysfs_streq(buf, "connect")) {
                usb_gadget_udc_start(udc);
                usb_gadget_connect(udc->gadget);
diff --git a/include/linux/usb/gadget.h b/include/linux/usb/gadget.h
index 1d74fb8..8c6880d 100644
--- a/include/linux/usb/gadget.h
+++ b/include/linux/usb/gadget.h
@@ -701,6 +701,10 @@ extern int usb_add_gadget_udc(struct device *parent, 
struct usb_gadget *gadget);
 extern void usb_del_gadget_udc(struct usb_gadget *gadget);
 extern char *usb_get_gadget_udc_name(void);
 
+extern int usb_otg_add_gadget_udc(struct device *parent,
+                                 struct usb_gadget *gadget,
+                                 struct device *otg_dev);
+
 /*-------------------------------------------------------------------------*/
 
 /* utility to simplify dealing with string descriptors */
-- 
2.7.4


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