Based on kernel version 4.16.1. Page generated on 2018-04-09 11:53 EST.
1 I2C device driver binding control from user-space 2 ================================================= 3 4 Up to kernel 2.6.32, many i2c drivers used helper macros provided by 5 <linux/i2c.h> which created standard module parameters to let the user 6 control how the driver would probe i2c buses and attach to devices. These 7 parameters were known as "probe" (to let the driver probe for an extra 8 address), "force" (to forcibly attach the driver to a given device) and 9 "ignore" (to prevent a driver from probing a given address). 10 11 With the conversion of the i2c subsystem to the standard device driver 12 binding model, it became clear that these per-module parameters were no 13 longer needed, and that a centralized implementation was possible. The new, 14 sysfs-based interface is described in the documentation file 15 "instantiating-devices", section "Method 4: Instantiate from user-space". 16 17 Below is a mapping from the old module parameters to the new interface. 18 19 Attaching a driver to an I2C device 20 ----------------------------------- 21 22 Old method (module parameters): 23 # modprobe <driver> probe=1,0x2d 24 # modprobe <driver> force=1,0x2d 25 # modprobe <driver> force_<device>=1,0x2d 26 27 New method (sysfs interface): 28 # echo <device> 0x2d > /sys/bus/i2c/devices/i2c-1/new_device 29 30 Preventing a driver from attaching to an I2C device 31 --------------------------------------------------- 32 33 Old method (module parameters): 34 # modprobe <driver> ignore=1,0x2f 35 36 New method (sysfs interface): 37 # echo dummy 0x2f > /sys/bus/i2c/devices/i2c-1/new_device 38 # modprobe <driver> 39 40 Of course, it is important to instantiate the "dummy" device before loading 41 the driver. The dummy device will be handled by i2c-core itself, preventing 42 other drivers from binding to it later on. If there is a real device at the 43 problematic address, and you want another driver to bind to it, then simply 44 pass the name of the device in question instead of "dummy".