Messages in this thread Patch in this message | | | From | "Cengiz C." <> | Date | Tue, 12 Dec 2017 19:43:09 +0300 | Subject | [PATCH v2] i2c: update i2c-dev.h warning in documentation |
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`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> ---
Hello Jonathan,
Thank you for the quick feedback.
I've removed unnecessary modifications and fixed some grammar in the commit message.
Documentation/i2c/dev-interface | 17 ++++++++++------- 1 file 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. -- 2.15.1
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