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.
Thanks for the improved cover letter.
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
Is a release planned ?
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.
because this would be good to have for functional tests.
Any feedback or suggestions are appreciated!
The AST1700 model is rather big and very similar to a SoC, without CPUs.
Perhaps we should move the model under hw/arm instead ?
Thanks,
C.
Kane
---
ChangeLog
---------
v2:
- Separate the AST1700 model into a standalone implementation
- Refine the mechanism for assigning the AST1700 board number
v1:
- Initial version
---
Kane-Chen-AS (17):
hw/arm/aspeed: Add LTPI controller
hw/arm/aspeed: Attach LTPI controller to AST27X0 platform
hw/arm/aspeed: Add AST1700 LTPI expander device model
hw/arm/aspeed: Integrate AST1700 device into AST27X0
hw/arm/aspeed: Integrate interrupt controller for AST1700
hw/arm/aspeed: Attach LTPI controller to AST1700 model
hw/arm/aspeed: Attach UART device to AST1700 model
hw/arm/aspeed: Attach SRAM device to AST1700 model
hw/arm/aspeed: Attach SPI device to AST1700 model
hw/arm/aspeed: Attach ADC device to AST1700 model
hw/arm/aspeed: Attach SCU device to AST1700 model
hw/arm/aspeed: Attach GPIO device to AST1700 model
hw/arm/aspeed: Attach I2C device to AST1700 model
hw/arm/aspeed: Attach WDT device to AST1700 model
hw/arm/aspeed: Model AST1700 I3C block as unimplemented device
hw/arm/aspeed: Model AST1700 SGPIOM block as unimplemented device
hw/arm/aspeed: Model AST1700 PWM block as unimplemented device
include/hw/arm/aspeed_soc.h | 20 +-
include/hw/intc/aspeed_intc.h | 2 +
include/hw/misc/aspeed_ast1700.h | 51 ++++++
include/hw/misc/aspeed_ltpi.h | 25 +++
hw/arm/aspeed_ast27x0.c | 154 ++++++++++++++--
hw/intc/aspeed_intc.c | 60 ++++++
hw/misc/aspeed_ast1700.c | 303 +++++++++++++++++++++++++++++++
hw/misc/aspeed_ltpi.c | 98 ++++++++++
hw/misc/meson.build | 2 +
9 files changed, 700 insertions(+), 15 deletions(-)
create mode 100644 include/hw/misc/aspeed_ast1700.h
create mode 100644 include/hw/misc/aspeed_ltpi.h
create mode 100644 hw/misc/aspeed_ast1700.c
create mode 100644 hw/misc/aspeed_ltpi.c
