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Commit 1d772e25 authored by Jean Delvare's avatar Jean Delvare Committed by Greg Kroah-Hartman
Browse files

[PATCH] I2C: Clarify the usage of i2c-dev.h 



Upon suggestion by Nils Roeder, here is an update to the i2c
documentation to clarify which header files user-space applications
relying on the i2c-dev interface should include.

Signed-off-by: default avatarJean Delvare <khali@linux-fr.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@suse.de>
parent a68e2f48

Documentation/i2c/dev-interface

+7 −4
Original line number Diff line number Diff line
@@ -14,9 +14,12 @@ 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.h>" and "#include <linux/i2c-dev.h>. 

Yes, I know, you should never include kernel header files, but until glibc 

knows about i2c, there is not much choice.

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 lm_sensors and is

meant to be included from user-space programs. You obviously want

the second one here.



Now, you have to decide which adapter you want to access. You should

inspect /sys/class/i2c-dev/ to decide this. Adapter numbers are assigned
@@ -78,7 +81,7 @@ Full interface description 
==========================



The following IOCTLs are defined and fully supported 

(see also i2c-dev.h and i2c.h):

(see also i2c-dev.h):



ioctl(file,I2C_SLAVE,long addr)

  Change slave address. The address is passed in the 7 lower bits of the