3aef852fc0
The implementation uses the system workqueue and a callback provided and registered by the application. The application callback is called in the context of the workqueue. Notification messages are stored in a queue and delivered to the callback in sequence. We cannot call application callback directly from the USB device stack thread because the behavior of arbitrary code provided by the application is unpredictable, and we do not want it to be executed in the same context where all events from the device controller are handled. Nor can we use the ZBUS subsystem directly. ZBUS offloads responsibility for defined behavior to the observers and application, and does not provide any way for the publisher to enforce defined behavior and execution context. ZBUS listener would be called from the USB thread context and is not acceptable. ZBUS subscriber does not provide delivery guarantee and cached message can be overwritten. ZBUS message subscriber has cumbersome global configuration and buffers that are too complicated to handle from USB configuration, and even if we would use it, defined behavior is not possible because of how listener and subscriber are handled. Signed-off-by: Johann Fischer <johann.fischer@nordicsemi.no>
53 lines
1.1 KiB
Plaintext
53 lines
1.1 KiB
Plaintext
# Copyright (c) 2022 Nordic Semiconductor ASA
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#
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# SPDX-License-Identifier: Apache-2.0
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menuconfig USB_DEVICE_STACK_NEXT
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bool "New USB device stack [EXPERIMENTAL]"
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select EXPERIMENTAL
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select UDC_DRIVER
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select HWINFO
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help
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New experimental USB device stack.
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if USB_DEVICE_STACK_NEXT
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module = USBD
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module-str = usbd
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source "subsys/logging/Kconfig.template.log_config"
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config USBD_SHELL
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bool "USB device shell"
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depends on SHELL
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help
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Enable USB device shell.
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config USBD_THREAD_INIT_PRIO
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int
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default 90
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help
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USB device thread initialization priority level.
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config USBD_THREAD_STACK_SIZE
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int "USB device stack thread stack size"
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default 1024
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help
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USB device stack thread stack size in bytes.
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config USBD_MAX_UDC_MSG
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int "Maximum number of UDC events"
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default 10
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help
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Maximum number of USB device controller events that can be queued.
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config USBD_MSG_SLAB_COUNT
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int "Maximum number of USB device notification messages"
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range 4 64
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default 8
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help
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Maximum number of USB device notification messages that can be queued.
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rsource "class/Kconfig"
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endif # USB_DEVICE_STACK_NEXT
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