711: Add DeviceStateHandler, DeviceCommand channel, and remote wakeup support r=Dirbaio a=alexmoon
Apologies for the size of this PR. Once I started getting into the Vbus power management side of my device I found a couple of areas of functionality missing from embassy-usb. Specifically, I need the application to be able to respond to changes in the USB device state in order to properly control the amount of power I'm drawing from Vbus. I also wanted to enable remote wakeup support for my device.
In order to enable device state monitoring, I've created a `DeviceStateHandler` trait and made it possible to pass in an optional reference a handler implementing that trait when creating the `UsbDeviceBuilder`.
Remote wakeup required a way to send commands to the bus which is exclusively owned by the `UsbDevice::run` method. This is the same problem we were discussing for enabling/disabling the device on Vbus power events. My solution is to allow an optional `Channel` to be provided to the `UsbDeviceBuilder` (via `UsbDeviceBuilder::new_with_channel`), allowing the application to send commands into the `run` method. Right now it supports enable, disable and remote wakeup commands.
Since there's now a way to dynamically enable and disable the device, I also added `Config::start_enabled` to control whether or not the `UsbDevice` should start in the enabled state. That also allowed me to make `UsbDeviceBuilder::build` sync again and move enabling the bus into `UsbDevice::run`.
This led to a few driver changes:
1. `Driver::enable` became `Driver::into_bus`
2. `Bus::enable`, `Bus::disable`, and `Bus::remote_wakeup` were added
3. I removed `Bus::reset`, `Bus::suspend`, and `Bus::resume` because they were only ever called based on the result of `Bus::poll`. It made more sense to me to have `Bus::poll` handle the driver-specific state management itself.
I've updated the `usb_hid_keyboard` example to take advantage of all these additional features.
Let me know what you think.
Thanks!
Co-authored-by: alexmoon <alex.r.moon@gmail.com>
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