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Subject[PATCH v2 06/10] usb: roles: Add usb role switch notifier.
Date
This patch adds notifier for drivers want to be informed of the usb role switch.

Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Cc: Hans de Goede <hdegoede@redhat.com>
Cc: Andy Shevchenko <andy.shevchenko@gmail.com>
Cc: John Stultz <john.stultz@linaro.org>
Suggested-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Signed-off-by: Yu Chen <chenyu56@huawei.com>
---
drivers/usb/roles/class.c | 20 +++++++++++++++++++-
include/linux/usb/role.h | 46 ++++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 65 insertions(+), 1 deletion(-)

diff --git a/drivers/usb/roles/class.c b/drivers/usb/roles/class.c
index f45d8df5cfb8..e2caaa665d6e 100644
--- a/drivers/usb/roles/class.c
+++ b/drivers/usb/roles/class.c
@@ -20,6 +20,7 @@ struct usb_role_switch {
struct device dev;
struct mutex lock; /* device lock*/
enum usb_role role;
+ struct blocking_notifier_head nh;

/* From descriptor */
struct device *usb2_port;
@@ -49,8 +50,10 @@ int usb_role_switch_set_role(struct usb_role_switch *sw, enum usb_role role)
mutex_lock(&sw->lock);

ret = sw->set(sw->dev.parent, role);
- if (!ret)
+ if (!ret) {
sw->role = role;
+ blocking_notifier_call_chain(&sw->nh, role, NULL);
+ }

mutex_unlock(&sw->lock);

@@ -58,6 +61,20 @@ int usb_role_switch_set_role(struct usb_role_switch *sw, enum usb_role role)
}
EXPORT_SYMBOL_GPL(usb_role_switch_set_role);

+int usb_role_switch_register_notifier(struct usb_role_switch *sw,
+ struct notifier_block *nb)
+{
+ return blocking_notifier_chain_register(&sw->nh, nb);
+}
+EXPORT_SYMBOL_GPL(usb_role_switch_register_notifier);
+
+int usb_role_switch_unregister_notifier(struct usb_role_switch *sw,
+ struct notifier_block *nb)
+{
+ return blocking_notifier_chain_unregister(&sw->nh, nb);
+}
+EXPORT_SYMBOL_GPL(usb_role_switch_unregister_notifier);
+
/**
* usb_role_switch_get_role - Get the USB role for a switch
* @sw: USB role switch
@@ -271,6 +288,7 @@ usb_role_switch_register(struct device *parent,
return ERR_PTR(-ENOMEM);

mutex_init(&sw->lock);
+ BLOCKING_INIT_NOTIFIER_HEAD(&sw->nh);

sw->allow_userspace_control = desc->allow_userspace_control;
sw->usb2_port = desc->usb2_port;
diff --git a/include/linux/usb/role.h b/include/linux/usb/role.h
index 9684a8734757..9e1ca663387a 100644
--- a/include/linux/usb/role.h
+++ b/include/linux/usb/role.h
@@ -41,6 +41,8 @@ struct usb_role_switch_desc {
bool allow_userspace_control;
};

+
+#if IS_ENABLED(CONFIG_USB_ROLE_SWITCH)
int usb_role_switch_set_role(struct usb_role_switch *sw, enum usb_role role);
enum usb_role usb_role_switch_get_role(struct usb_role_switch *sw);
struct usb_role_switch *usb_role_switch_get(struct device *dev);
@@ -50,5 +52,49 @@ struct usb_role_switch *
usb_role_switch_register(struct device *parent,
const struct usb_role_switch_desc *desc);
void usb_role_switch_unregister(struct usb_role_switch *sw);
+int usb_role_switch_register_notifier(struct usb_role_switch *sw,
+ struct notifier_block *nb);
+int usb_role_switch_unregister_notifier(struct usb_role_switch *sw,
+ struct notifier_block *nb);
+#else
+static inline int usb_role_switch_set_role(struct usb_role_switch *sw,
+ enum usb_role role)
+{
+ return 0;
+}
+
+static inline enum usb_role usb_role_switch_get_role(struct usb_role_switch *sw)
+{
+ return USB_ROLE_NONE;
+}
+
+static inline struct usb_role_switch *usb_role_switch_get(struct device *dev)
+{
+ return ERR_PTR(-ENODEV);
+}
+
+static inline void usb_role_switch_put(struct usb_role_switch *sw) { }
+
+static inline struct usb_role_switch *
+usb_role_switch_register(struct device *parent,
+ const struct usb_role_switch_desc *desc)
+{
+ return ERR_PTR(-ENODEV);
+}
+
+static inline void usb_role_switch_unregister(struct usb_role_switch *sw) { }
+
+static int usb_role_switch_register_notifier(struct usb_role_switch *sw,
+ struct notifier_block *nb)
+{
+ return -ENODEV;
+}
+
+static int usb_role_switch_unregister_notifier(struct usb_role_switch *sw,
+ struct notifier_block *nb)
+{
+ return -ENODEV;
+}
+#endif

#endif /* __LINUX_USB_ROLE_H */
--
2.15.0-rc2
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