Thanks for the reply. Sorry for not being clear that it was for the multiplexing of I2C. My link into the mailing list implied that it was solely for the later and not for all I2C in general. Regards, Lindsey -----Original Message----- From: Jean Delvare [mailto:khali@xxxxxxxxxxxx] Sent: Tuesday, July 14, 2009 3:57 AM To: Lindsey Ings -X (ingsl - Yoh Services LLC at Cisco) Cc: linux-i2c@xxxxxxxxxxxxxxx; giometti@xxxxxxxxxxxx Subject: Re: Sample DTS entries and sample user space code On Fri, 10 Jul 2009 17:09:47 -0400, Lindsey Ings -X (ingsl - Yoh Services LLC at Cisco) wrote: > > > Resend of message in plain text form. > > > I understand the concepts involved in this project but that doesn't help me actually make use of it. For reference for other readers who have no clue what you're talking about: Lindsey is referring to Rodolfo's I2C multiplexing support project, described at: http://i2c.wiki.kernel.org/index.php/I2C_bus_multiplexing > Is there a sample of how to put the mux and (if feasible) I2C clients in a DTS? Not yet. Rodolfo's code is not even in mainline. But once implementation is complete, then yes it should be possible to declare I2C multiplexers and other I2C devices in a DTS. > Also is there a user application sample of how to access the devices downstream from the mux? This wouldn't make sense. Multiplexing is handled in the kernel and user-space does not even know it is happening. > Are the mux's created as a device so that the devices downstream are accessed as non-mux'd devices? i.e. is dev D in segment 2 (from the diagram on the wiki) accessed as so: > > int fd; > fd = open( "/dev/i2c-2", O_RDWR ); > > #define ADDRESS 0x38 // address of dev D > ioctl( fd, I2C_SLAVE, ADDRESS ) > > // Now r/w dev D > > // Write 0xAA to dev D > i2c_smbus_write_byte( fd, 0xAA ); > // etc. Yes, this is how the code would look like. Note that I am still waiting for Rodolfo to update his patch set so that it applies again on top of Linus' latest kernel. -- Jean Delvare -- To unsubscribe from this list: send the line "unsubscribe linux-i2c" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
