Shulou(Shulou.com)06/02 Report--

1.USB features different equipment types, unified interface support hot-swappable flexible power supply mode, multi-stage rate support 2. 5%. The classification of OHCI is mainly USB chip UHCI on non-PC system and PC motherboard with SiShe ALi chipset, which is mostly USB controller chip on Intel and Via motherboard. The hardware circuit of UHCI is simpler and more cost-effective than OHCI, but the driver is complex. But they are all specified by USB1.1. EHCI is developed by several manufacturers such as Intel, and compatible with OHCI UHCI follows USB2.0 specification 3. Hierarchical device: a device is what we understand as a device, such as a keyboard is a device and a USB disk is a device configuration: configuration is a collection of functions, such as a USB headset that can record and play, then there can be three configuration interfaces: as above, it is divided into recording interfaces, playback interface endpoints: for example, there are two endpoints in the playback interface, one is the left channel One is that the endpoint of the right channel is the basic unit of communication, and the direction is determined that the pipe represents the ability to communicate between the endpoint and the endpoint 4. Transmission unit

* transaction: a transaction generally consists of token package, packet (optional), and handshake package.

Token package: used to start a transaction, always sent by the host. Packet: can be from host to device or from device to host, and the direction is determined by the token packet. Handshake packet: typically, the recipient of the data sends a handshake packet (ACK or NAK).

Transactions generally consist of token packets, data packets (optional), and handshake packets.

USB protocol specifies four types of transmission: control transmission, batch transmission, synchronous transmission, interrupt transmission control transmission: the control transmission is responsible for setting some control information to the USB, and the pipeline for transmitting such transactions is the control pipeline. Control piping is required in USB equipment. Control transmission is also divided into three stages, namely, token stage, data transfer stage and handshake stage. Interrupt transmission: the amount of data that interrupts a thing is very small, and it is generally used to inform Host of the arrival of an event, such as USB mouse, mouse movement or mouse click, and other operations will send events to Host through the interrupt pipeline. It is also divided into three stages: token stage, data transmission stage and handshake stage. Synchronous transmission: this is a transaction that ensures the synchronization of transmission. For example, this kind of transaction is used when transmitting video data in the USB camera, this kind of transaction can guarantee a fixed amount of transmission per second, and unlike Bulk transmission, it allows a certain bit error rate. The synchronous transfer transaction has only two phases, the token phase and the data phase. Because it does not care about the correctness of the data, there is no handshake phase. Batch transfer: it is used to transfer a large amount of data to ensure that there is no data loss, but it is not guaranteed to finish in a specific time. U disk uses batch transmission. 5. Naming sysfs USB naming

2-1 rig 1.0 device-Port: configuration. Interface

The first port of the second device, using interface 1 configured with 0

6. Driving architecture

USB Core

USB Core provides some core algorithms, services for other device drivers, and an interface for accessing and controlling USB hardware, regardless of what kind of host controller the system is currently

The relationship between USB Core and USB host controller USB device driver is as follows:

Block layer: Net layer: Char layer:-USB device driver-USB Core-- USB Host Controller (HCD)-hardware

HCD provides an abstraction of the host controller hardware and hides the hardware details. HCD is only responsible for USB Core. This means that we write USB drivers on the basis of calling the USB Core interface.

Our next source code analysis starts with HCD.

Original address: http://coderdock.com

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