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| author | Cengiz C <cengizc@gmail.com> | 2017-12-12 19:43:09 +0300 |
|---|---|---|
| committer | Jonathan Corbet <corbet@lwn.net> | 2017-12-21 13:39:30 -0700 |
| commit | 91b28aeb17ce13065d745a1f92c95011c10ba75a (patch) | |
| tree | 426ec7d073a1ff2ed0b75ca5b3ae77af8550874f /Documentation/i2c | |
| parent | 90b2a01e68167665a3f86c477414e795cd4a0139 (diff) | |
| download | lwn-91b28aeb17ce13065d745a1f92c95011c10ba75a.tar.gz lwn-91b28aeb17ce13065d745a1f92c95011c10ba75a.zip | |
i2c: update i2c-dev.h warning in documentation
`Documentation/i2c/dev-interface` gives examples for accessing i2c from
userspace.
There's a note that warns developers about the two `i2c-dev.h` header
files which were shipped with the kernel and i2c-tools separately.
However, following i2c-tools commits suggest that the header files are now
identical (in functionality) and `i2c_*` helper functions are now defined
in a separate header called `i2c/smbus.h`, which is distributed with
i2c-tools:
commit 652619121974 ("Minimize differences with kernel flavor")
commit 93caf007f4cb ("Move SMBus helper functions to include/i2c/smbus.h")
Thus, I've converted the warning paragraph into a historical note and
updated the suggested header files.
Signed-off-by: Cengiz Can <cengizc@gmail.com>
Cc: Wolfram Sang <wsa@the-dreams.de>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Diffstat (limited to 'Documentation/i2c')
| -rw-r--r-- | Documentation/i2c/dev-interface | 17 |
1 files changed, 10 insertions, 7 deletions
diff --git a/Documentation/i2c/dev-interface b/Documentation/i2c/dev-interface index 5ff19447ac44..d04e6e4964ee 100644 --- a/Documentation/i2c/dev-interface +++ b/Documentation/i2c/dev-interface @@ -17,13 +17,16 @@ i2c-10, ...). All 256 minor device numbers are reserved for i2c. C example ========= -So let's say you want to access an i2c adapter from a C program. The -first thing to do is "#include <linux/i2c-dev.h>". Please note that -there are two files named "i2c-dev.h" out there, one is distributed -with the Linux kernel and is meant to be included from kernel -driver code, the other one is distributed with i2c-tools and is -meant to be included from user-space programs. You obviously want -the second one here. +So let's say you want to access an i2c adapter from a C program. +First, you need to include these two headers: + + #include <linux/i2c-dev.h> + #include <i2c/smbus.h> + +(Please note that there are two files named "i2c-dev.h" out there. One is +distributed with the Linux kernel and the other one is included in the +source tree of i2c-tools. They used to be different in content but since 2012 +they're identical. You should use "linux/i2c-dev.h"). Now, you have to decide which adapter you want to access. You should inspect /sys/class/i2c-dev/ or run "i2cdetect -l" to decide this. |