1================================================= 2I2C device driver binding control from user-space 3================================================= 4 5Up to kernel 2.6.32, many i2c drivers used helper macros provided by 6<linux/i2c.h> which created standard module parameters to let the user 7control how the driver would probe i2c buses and attach to devices. These 8parameters were known as "probe" (to let the driver probe for an extra 9address), "force" (to forcibly attach the driver to a given device) and 10"ignore" (to prevent a driver from probing a given address). 11 12With the conversion of the i2c subsystem to the standard device driver 13binding model, it became clear that these per-module parameters were no 14longer needed, and that a centralized implementation was possible. The new, 15sysfs-based interface is described in the documentation file 16"instantiating-devices", section "Method 4: Instantiate from user-space". 17 18Below is a mapping from the old module parameters to the new interface. 19 20Attaching a driver to an I2C device 21----------------------------------- 22 23Old method (module parameters):: 24 25 # modprobe <driver> probe=1,0x2d 26 # modprobe <driver> force=1,0x2d 27 # modprobe <driver> force_<device>=1,0x2d 28 29New method (sysfs interface):: 30 31 # echo <device> 0x2d > /sys/bus/i2c/devices/i2c-1/new_device 32 33Preventing a driver from attaching to an I2C device 34--------------------------------------------------- 35 36Old method (module parameters):: 37 38 # modprobe <driver> ignore=1,0x2f 39 40New method (sysfs interface):: 41 42 # echo dummy 0x2f > /sys/bus/i2c/devices/i2c-1/new_device 43 # modprobe <driver> 44 45Of course, it is important to instantiate the "dummy" device before loading 46the driver. The dummy device will be handled by i2c-core itself, preventing 47other drivers from binding to it later on. If there is a real device at the 48problematic address, and you want another driver to bind to it, then simply 49pass the name of the device in question instead of "dummy". 50