1*4882a593Smuzhiyun================================================================ 2*4882a593SmuzhiyunI2C device driver binding control from user-space in old kernels 3*4882a593Smuzhiyun================================================================ 4*4882a593Smuzhiyun 5*4882a593Smuzhiyun.. NOTE:: 6*4882a593Smuzhiyun Note: this section is only relevant if you are handling some old code 7*4882a593Smuzhiyun found in kernel 2.6. If you work with more recent kernels, you can 8*4882a593Smuzhiyun safely skip this section. 9*4882a593Smuzhiyun 10*4882a593SmuzhiyunUp to kernel 2.6.32, many I2C drivers used helper macros provided by 11*4882a593Smuzhiyun<linux/i2c.h> which created standard module parameters to let the user 12*4882a593Smuzhiyuncontrol how the driver would probe I2C buses and attach to devices. These 13*4882a593Smuzhiyunparameters were known as ``probe`` (to let the driver probe for an extra 14*4882a593Smuzhiyunaddress), ``force`` (to forcibly attach the driver to a given device) and 15*4882a593Smuzhiyun``ignore`` (to prevent a driver from probing a given address). 16*4882a593Smuzhiyun 17*4882a593SmuzhiyunWith the conversion of the I2C subsystem to the standard device driver 18*4882a593Smuzhiyunbinding model, it became clear that these per-module parameters were no 19*4882a593Smuzhiyunlonger needed, and that a centralized implementation was possible. The new, 20*4882a593Smuzhiyunsysfs-based interface is described in :doc:`instantiating-devices`, section 21*4882a593Smuzhiyun"Method 4: Instantiate from user-space". 22*4882a593Smuzhiyun 23*4882a593SmuzhiyunBelow is a mapping from the old module parameters to the new interface. 24*4882a593Smuzhiyun 25*4882a593SmuzhiyunAttaching a driver to an I2C device 26*4882a593Smuzhiyun----------------------------------- 27*4882a593Smuzhiyun 28*4882a593SmuzhiyunOld method (module parameters):: 29*4882a593Smuzhiyun 30*4882a593Smuzhiyun # modprobe <driver> probe=1,0x2d 31*4882a593Smuzhiyun # modprobe <driver> force=1,0x2d 32*4882a593Smuzhiyun # modprobe <driver> force_<device>=1,0x2d 33*4882a593Smuzhiyun 34*4882a593SmuzhiyunNew method (sysfs interface):: 35*4882a593Smuzhiyun 36*4882a593Smuzhiyun # echo <device> 0x2d > /sys/bus/i2c/devices/i2c-1/new_device 37*4882a593Smuzhiyun 38*4882a593SmuzhiyunPreventing a driver from attaching to an I2C device 39*4882a593Smuzhiyun--------------------------------------------------- 40*4882a593Smuzhiyun 41*4882a593SmuzhiyunOld method (module parameters):: 42*4882a593Smuzhiyun 43*4882a593Smuzhiyun # modprobe <driver> ignore=1,0x2f 44*4882a593Smuzhiyun 45*4882a593SmuzhiyunNew method (sysfs interface):: 46*4882a593Smuzhiyun 47*4882a593Smuzhiyun # echo dummy 0x2f > /sys/bus/i2c/devices/i2c-1/new_device 48*4882a593Smuzhiyun # modprobe <driver> 49*4882a593Smuzhiyun 50*4882a593SmuzhiyunOf course, it is important to instantiate the ``dummy`` device before loading 51*4882a593Smuzhiyunthe driver. The dummy device will be handled by i2c-core itself, preventing 52*4882a593Smuzhiyunother drivers from binding to it later on. If there is a real device at the 53*4882a593Smuzhiyunproblematic address, and you want another driver to bind to it, then simply 54*4882a593Smuzhiyunpass the name of the device in question instead of ``dummy``. 55