MSS framework

The overall project goal of MSS framework is to provide better MMC support and extend the existing MMC framework to support SD, SDIO and CE-ATA protocol. Currently there is some support in the kernel for MMC/SD, however it has some limitations:-

• Currently, MMC framework are often tightly coupled to the MMC block driver. This is not quite ideal and leads to the framework is hard to support future SDIO device, which support I/O device on SD-like protocol.
• There is no standard multiple card support. It is up to the hardware driver take care of multiple card support.
• There is no clear separation among different protocols. SD code and MMC code are mixed together. It is hard to maintain.

MSS Framework Design

The MSS framework is designed to address these issues and provide the following features:

• multiple protocol support
• common multiple card support (including multi-slot and multi-controller). MSS framework support multiple MMC/SD card, multiple MMC/SD card with SDIO card and multiple SDIO card.
• power management event
• Hot removable support
• device driver support, including block device driver and others.
• MMC block mode

Below is the example architecture:

To achieve all this, MSS basically splits it into three components:

• Platform driver: The platform driver contains the real code to talk with the hardware. This is the only platform-dependent part in MSS.
• Protocol driver: The protocol driver contains the basic protocol primitives and operations.
• Device driver: The device driver work as the interface to other part of the kernel

MSS is still very much work in progress and currently the only supported platform is the pxa2xx.

Supported platform:

Mainstone II

Supported protocol:

MMC

Supported device driver:

block device

Latest release:

The latest MSS framework snapshot(version 0.10) was release on 20th October 2006 and can be found at http://pxa-linux.sf.net/mss_snapshot20061020.tgz.