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author | Linus Torvalds <torvalds@linux-foundation.org> | 2009-12-08 11:12:16 -0500 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2009-12-08 11:12:16 -0500 |
commit | 41440ffe21f29bdb985cab76b2d0b06d83e63b19 (patch) | |
tree | 1d7d1ff6f699ccbabb71c7bc4172f7d15bc4bc45 /Documentation/i2c/old-module-parameters | |
parent | dad3de7d0090280f44ff27131ed2878f1ab6ddad (diff) | |
parent | 6471b68982d3bb1a593c3e183c804ecf830125d3 (diff) |
Merge branch 'i2c-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jdelvare/staging
* 'i2c-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jdelvare/staging:
i2c-stub: Documentation update
i2c-stub: Allow user to disable some commands
i2c-stub: Implement I2C block support
i2c: Refactor for_each callbacks
i2c-i801: Retry on lost arbitration
i2c: Remove big kernel lock from i2cdev_open
ics932s401: Clean up detect function
i2c: Simplify i2c_detect_address
i2c: Drop probe, ignore and force module parameters
i2c: Add missing __devinit markers to old i2c adapter drivers
i2c: Bus drivers don't have to support I2C_M_REV_DIR_ADDR
i2c: Prevent priority inversion on top of bus lock
i2c-voodoo3: Delete
i2c-powermac: Drop temporary name buffer
i2c-powermac: Include the i2c_adapter in struct pmac_i2c_bus
i2c-powermac: Log errors
i2c-powermac: Refactor i2c_powermac_smbus_xfer
i2c-powermac: Reject unsupported I2C transactions
i2c/chips: Move ds1682 to drivers/misc
Diffstat (limited to 'Documentation/i2c/old-module-parameters')
-rw-r--r-- | Documentation/i2c/old-module-parameters | 44 |
1 files changed, 44 insertions, 0 deletions
diff --git a/Documentation/i2c/old-module-parameters b/Documentation/i2c/old-module-parameters new file mode 100644 index 000000000000..8e2b629d533c --- /dev/null +++ b/Documentation/i2c/old-module-parameters | |||
@@ -0,0 +1,44 @@ | |||
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". | ||