Hi,
On 16-02-18 15:07, Andy Shevchenko wrote:
On Fri, Feb 16, 2018 at 12:47 PM, Hans de Goede <hdegoede@xxxxxxxxxx> wrote:
USB role switch is a device that can be used to choose the
data role for USB connector. With dual-role capable USB
controllers, the controller itself will be the switch, but
on some platforms the USB host and device controllers are
separate IPs and there is a mux between them and the
connector. On those platforms the mux driver will need to
register the switch.
With USB Type-C connectors, the host-to-device relationship
is negotiated over the Configuration Channel (CC). That
means the USB Type-C drivers need to be in control of the
role switch. The class provides a simple API for the USB
Type-C drivers for the control.
For other types of USB connectors (mainly microAB) the class
provides user space control via sysfs attribute file that
can be used to request role swapping from the switch.
+static int __switch_match(struct device *dev, const void *name)
bool?
+{
+ return !strcmp((const char *)name, dev_name(dev));
+}
+static ssize_t role_store(struct device *dev, struct device_attribute *attr,
+ const char *buf, size_t size)
+{
+ struct usb_role_switch *sw = to_role_switch(dev);
+ int ret;
+
+ ret = sysfs_match_string(usb_roles, buf);
+ if (ret < 0) {
+ bool res;
+
+ /* Extra check if the user wants to disable the switch */
+ ret = kstrtobool(buf, &res);
+ if (ret || res)
+ return -EINVAL;
+ }
+
+ ret = usb_role_switch_set_role(sw, ret);
+ if (!ret)
+ ret = size;
+
+ return ret;
Perhaps
ret = ...
if (ret)
return ret;
return size;
Ack, that is better, fixed for v2.
Regards,
Hans
+}
+struct usb_role_switch *
+usb_role_switch_register(struct device *parent,
+ const struct usb_role_switch_desc *desc)
+{
+ struct usb_role_switch *sw;
+ int ret;
+
+ if (!desc || !desc->set)
+ return ERR_PTR(-EINVAL);
+
+ sw = kzalloc(sizeof(*sw), GFP_KERNEL);
+ if (!sw)
+ return ERR_PTR(-ENOMEM);
+ ret = device_register(&sw->dev);
+ if (ret) {
+ put_device(&sw->dev);
Memory leak?
+ return ERR_PTR(ret);
+ }
+
+ /* TODO: Symlinks for the host port and the device controller. */
+
+ return sw;
+}
+void usb_role_switch_unregister(struct usb_role_switch *sw)
+{
+ if (sw && !IS_ERR(sw))
!IS_ERR_OR_NULL() ?
+ device_unregister(&sw->dev);
+}
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