interconnect

下面的属于是用来描述一个interconnect的，如omap3530就用到了L3,L4 interconnect。

• Initiator: Module able to initiate read and write requests to the chip interconnect (typically: processors,DMA, etc.).

这个好比网络的客户端，可以向其他服务器发送一个请求(其实是soc上其他的模块)。

• Target: Unlike an initiator, a target module cannot generate read/write requests to the chip interconnect, but it can respond to these requests. However, it may generate interrupts or a DMA request to the system (typically: peripherals, memory controllers).
NOTE: A module can have several separate ports; therefore, a module can be both an initiator and a target.

这个好比是服务器，比如存储服务器(ram or rom等)。

• Agent: Each connection of one module to one interconnect is done using an agent, which is an adaptation (sometimes configurable) between the module and the interconnect. A target module is connected by a target agent (TA), and an initiator module is connected by an initiator agent (IA).

一个通用的模块，比如啥GPIO，本身可能不继承啥复杂的总线协议，那么就需要一个代理了。

• OCP: Open-core protocol () is point-to-point standard protocol between one master port and one slave port.
• OCP master port: Port that can generate OCP commands. An initiator includes at least one master port.
• OCP slave port: Port that responds to OCP commands. A target includes one slave port.
• Interconnect: The decoding, routing, and arbitration logic that enables the connection between multiple initiator modules and multiple target modules connected on it.
• Register target (RT): Special TA used to access the interconnect internal configuration registers.
• Dataflow signal: Any OCP signal that is part of a clearly identified OCP transfer or dataflow (typically: command, address, byte enables, etc.). The signal behavior is defined by the OCP protocol semantics.
• Sideband signal: Any OCP signal whose behavior is not associated to a precise OCP transaction or dataflow. The OCP standard does not define specific semantics for these signals.icnt
• Out-of-band error: Any OCP signal whose behavior is associated to an error-reporting scheme of the device, as opposed to in-band errors.