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| author | Sam Hansen <hansens@google.com> | 2018-04-13 10:42:56 -0700 |
|---|---|---|
| committer | Wolfram Sang <wsa@the-dreams.de> | 2018-04-18 10:09:15 +0200 |
| commit | b50cb3eaf7c8d13e427f991f7d52b485ca0fc65f (patch) | |
| tree | d044ed8d69fc2a587acafdc95fb4fe131c66b3fa /Documentation | |
| parent | 675edea10badf5b3446275d60e1bd2105905d498 (diff) | |
| download | linux-b50cb3eaf7c8d13e427f991f7d52b485ca0fc65f.tar.bz2 | |
Documentation/i2c: sync docs with current state of i2c-tools
Currently, Documentation/i2c/dev-interface describes the use of
i2c_smbus_* helper routines as static inlined functions provided by
linux/i2c-dev.h. Work has been done to refactor the linux/i2c-dev.h file
in the i2c-tools project out into its own library. As a result, these
docs have become stale.
This patch corrects the discrepancy and directs the reader to the
i2c-tools project for more information.
Signed-off-by: Sam Hansen <hansens@google.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/i2c/dev-interface | 16 |
1 files changed, 5 insertions, 11 deletions
diff --git a/Documentation/i2c/dev-interface b/Documentation/i2c/dev-interface index c8737d502791..f92ee1f59914 100644 --- a/Documentation/i2c/dev-interface +++ b/Documentation/i2c/dev-interface @@ -23,11 +23,6 @@ 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. Adapter numbers are assigned somewhat dynamically, so you can not @@ -140,8 +135,8 @@ ioctl(file, I2C_RDWR, struct i2c_rdwr_ioctl_data *msgset) set in each message, overriding the values set with the above ioctl's. ioctl(file, I2C_SMBUS, struct i2c_smbus_ioctl_data *args) - Not meant to be called directly; instead, use the access functions - below. + If possible, use the provided i2c_smbus_* methods described below instead + of issuing direct ioctls. You can do plain i2c transactions by using read(2) and write(2) calls. You do not need to pass the address byte; instead, set it through @@ -166,10 +161,9 @@ what happened. The 'write' transactions return 0 on success; the returns the number of values read. The block buffers need not be longer than 32 bytes. -The above functions are all inline functions, that resolve to calls to -the i2c_smbus_access function, that on its turn calls a specific ioctl -with the data in a specific format. Read the source code if you -want to know what happens behind the screens. +The above functions are made available by linking against the libi2c library, +which is provided by the i2c-tools project. See: +https://git.kernel.org/pub/scm/utils/i2c-tools/i2c-tools.git/. Implementation details |