On 11/5/25 04:58, Kane Chen wrote:
From: Kane-Chen-AS <[email protected]>
Hi all,
LTPI (LVDS Tunneling Protocol & Interface) is defined in the OCP DC-SCM
2.0 specification (see Figure 2):
https://www.opencompute.org/documents/ocp-dc-scm-2-0-ltpi-ver-1-0-pdf
LTPI provides a protocol and physical interface for tunneling various
low-speed signals between the Host Processor Module (HPM) and the
Satellite Controller Module (SCM). In Figure 2 of the specification,
the AST27x0 SoC (left) integrates two LTPI controllers, allowing it to
connect to up to two AST1700 boards. On the other side, the AST1700
consolidates HPM FPGA functions and multiple peripheral interfaces
(GPIO, UART, I2C, I3C, etc.) onto a single board.
Because the AST1700 exposes additional I/O interfaces (GPIO, I2C, I3C,
and others), it acts as an I/O expander. Once connected over LTPI,
the AST27x0 can control additional downstream devices through this link.
This patch series introduces a basic LTPI controller model and wires it
into the AST27x0 SoC. It also adds the AST1700-specific LTPI expander
device and gradually connects common peripherals on the AST1700 model.
For blocks that are not yet functionally implemented (I3C, SGPIOM, PWM),
their MMIO regions are modeled as unimplemented devices to reserve
address space and make the missing functionality explicit, ensuring that
guest probing remains stable.
In the official release images, the AST1700 functions are not included
by default. To test the AST1700-related functionality, please include
the following DTS files for probing:
https://github.com/AspeedTech-BMC/linux/blob/aspeed-master-v6.6/arch/arm64/boot/dts/aspeed/aspeed-ltpi0.dtsi
https://github.com/AspeedTech-BMC/linux/blob/aspeed-master-v6.6/arch/arm64/boot/dts/aspeed/aspeed-ltpi1.dtsi
After including these DTS files in the BMC image, you can verify LTPI
functionality using the following scenarios:
1. In U-Boot:
Run the ltpi command to trigger the LTPI connection and display the
current connection status.
2. In BMC Linux:
Run i2cdetect -y <16-38> to scan and test the I2C buses exposed by
the AST1700.
Any feedback or suggestions are appreciated!
Thanks for the update. The models look better. Let's consider them
for QEMU 11.0.
Did you run "make check" and "make check-functional" ?
Thanks,
C.
