Hello, I work for an networking storage company, supporting linux for our custom embedded hardware. My company makes extensive use of the I2C bus in our products. Some of these product are chassis/blade based and as a result many times a given I2C bus is multiplexed into several bus segments to prevent address conflicts when many I2C devices exist with the same address. Some muxes are I2C based, some based on GPIO lines or CPLDs, etc. In my experience this is a common hardware solution, but it is difficult to fit into the existing i2c driver implementation. I wanted to design a nice architecture to handle these bus multiplexors in the most transparent and simple way possible. My solution was to create a new i2c adapter driver (i2c-virtual.c) which registers a new i2c adapter/bus for each multiplexed bus segment. This virtual adapter then makes calls to the real i2c adapter to select the mux, perform the transfer, and deselect again. Locking of the buses is handled. The code also prevents "aliasing" of the same I2C device onto multiple virtual I2C buses, putting all non-multiplexed devices on the real bus, and only multiplexed devices on the virtual busses. The result is that all the existing i2c client drivers and sensor drivers work with this multiplexed hardware without any changes, just by scanning the additional buses. If anyone from this your group is interested in reviewing or integrating this code into the official sources, please let me know and I'll send a patch. BTW, do you have a mailing list? I couldn't find one. Best regards, Brian Kuschak Brocade Communications Sys. __________________________________ Do you Yahoo!? Yahoo! SiteBuilder - Free, easy-to-use web site design software http://sitebuilder.yahoo.com
