On Sat, May 18, 2024 at 06:12:07PM +0530, Siddharth Vadapalli wrote: > The CPSW Proxy Client driver interfaces with Ethernet Switch Firmware on > a remote core to enable Ethernet functionality for applications running > on Linux. The Ethernet Switch Firmware (EthFw) is in control of the CPSW > Ethernet Switch on the SoC and acts as the Server, offering services to > Clients running on various cores. I'm not sure we as a community what this architecture. We want Linux to be driving the hardware, not firmware. So expect linux to be running the server. > +The "am65-cpsw-nuss.c" driver in Linux at: > +drivers/net/ethernet/ti/am65-cpsw-nuss.c > +provides Ethernet functionality for applications on Linux. > +It also handles both the control-path and data-path, namely: > +Control => Configuration of the CPSW Peripheral > +Data => Configuration of the DMA Channels to transmit/receive data So nuss is capable of controlling the hardware. nuss has an upper interface which is switchdev, and a lower interface which somehow acts on the hardware, maybe invoking RPCs into the firmware? So it is not too big a step to put the server functionality in Linux, on top of the nuss driver. Now take a step backwards. This concept of a switch with different CPUs attached to it is nothing special. Some Marvell switches have a Z80 connected to a dedicated port of the switch. You can run applications on that Z80. Those applications might be as simple as spanning tree, so you can have a white box 8 port ethernet switch without needing an external CPU. But there is an SDK, you could run any sort of application on the Z80. The microchip LAN996x switch has a Cortex A7 CPU, but also a PCIe interface. Linux can control the switch via the PCIe interface, but there could also be applications running on the Cortex. Look at the Broadcom BCM89586M: https://docs.broadcom.com/doc/89586M-PB It is similar to the microchip device, an M7 CPU, and a PCIe interface. It seems like a Linux host could be controlling the switch via PCIe, and applications running on the M7. I expect there are more examples, but you get the idea. A completely different angle to look at is VF/PF and eswitches. A server style CPU running virtual machines, a VM getting a VF passed through to it. This is not something i know much about, so we might need to pull in some data centre specialists. But we have a different CPU, a virtual CPU, making use of part of the switch. Its the same concept really. My main point is, please start with an abstract view of the problem. A lot of the solution should be generic, it can be applied to all these devices. And then there probably needs to be a small part which is specific to TI devices. It could be parts of the solutions already exist, e.g. VF/PF have port represents, which might be a useful concept here as well. Switchdev exists and provides a generic interface for configuring switches... Andrew
