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i2c: Drop probe, ignore and force module parameters

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The legacy probe and force module parameters are obsolete now, the
same can be achieved using the new_device sysfs interface, which is
both more flexible and cheaper (it is implemented by i2c-core rather
than replicated in every driver module.)

The legacy ignore module parameters can be dropped as well. Ignoring
can be done by instantiating a "dummy" device at the problematic
address.

This is the first step of a huge cleanup to i2c-core's i2c_detect
function, i2c.h's I2C_CLIENT_INSMOD* macros, and all drivers that made
use of them.

Signed-off-by: Jean Delvare <khali@linux-fr.org>
This commit is contained in:
Jean Delvare 2009-12-06 17:06:24 +01:00
parent abe38388e5
commit c7b25a9e96
3 changed files with 46 additions and 154 deletions
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44
Documentation/i2c/old-module-parameters Normal file
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I2C device driver binding control from user-space
=================================================
Up to kernel 2.6.32, many i2c drivers used helper macros provided by
<linux/i2c.h> which created standard module parameters to let the user
control how the driver would probe i2c buses and attach to devices. These
parameters were known as "probe" (to let the driver probe for an extra
address), "force" (to forcibly attach the driver to a given device) and
"ignore" (to prevent a driver from probing a given address).
With the conversion of the i2c subsystem to the standard device driver
binding model, it became clear that these per-module parameters were no
longer needed, and that a centralized implementation was possible. The new,
sysfs-based interface is described in the documentation file
"instantiating-devices", section "Method 4: Instantiate from user-space".
Below is a mapping from the old module parameters to the new interface.
Attaching a driver to an I2C device
-----------------------------------
Old method (module parameters):
# modprobe <driver> probe=1,0x2d
# modprobe <driver> force=1,0x2d
# modprobe <driver> force_<device>=1,0x2d
New method (sysfs interface):
# echo <device> 0x2d > /sys/bus/i2c/devices/i2c-1/new_device
Preventing a driver from attaching to an I2C device
---------------------------------------------------
Old method (module parameters):
# modprobe <driver> ignore=1,0x2f
New method (sysfs interface):
# echo dummy 0x2f > /sys/bus/i2c/devices/i2c-1/new_device
# modprobe <driver>
Of course, it is important to instantiate the "dummy" device before loading
the driver. The dummy device will be handled by i2c-core itself, preventing
other drivers from binding to it later on. If there is a real device at the
problematic address, and you want another driver to bind to it, then simply
pass the name of the device in question instead of "dummy".