From: Sam Hansen <hansens@google.com>
To: linux-i2c@vger.kernel.org
Cc: Sam Hansen <hansens@google.com>,
wsa@the-dreams.de, corbet@lwn.net, linux-doc@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: [PATCH v3 2/3] Documentation/i2c: sync docs with current state of i2c-tools
Date: Fri, 13 Apr 2018 10:42:56 -0700 [thread overview]
Message-ID: <20180413174257.139182-2-hansens@google.com> (raw)
In-Reply-To: <20180413174257.139182-1-hansens@google.com>
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>
---
No changes from v2.
Documentation/i2c/dev-interface | 16 +++++-----------
1 file 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
--
2.17.0.484.g0c8726318c-goog
next prev parent reply other threads:[~2018-04-13 17:42 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-04-13 17:42 [PATCH v3 1/3] Documentation/i2c: whitespace cleanup Sam Hansen
2018-04-13 17:42 ` Sam Hansen [this message]
2018-04-18 8:09 ` [PATCH v3 2/3] Documentation/i2c: sync docs with current state of i2c-tools Wolfram Sang
2018-04-18 8:21 ` Wolfram Sang
2018-04-18 18:17 ` Sam Hansen
2018-04-13 17:42 ` [PATCH v3 3/3] Documentation/i2c: adopt kernel commenting style in examples Sam Hansen
2018-04-18 8:10 ` Wolfram Sang
2018-04-18 8:08 ` [PATCH v3 1/3] Documentation/i2c: whitespace cleanup Wolfram Sang
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