Const buffer pointers for SMBus/I2C block write functions

Const buffer pointers for SMBus/I2C block write functions

[Roman Fietze]

Hello List Members,

I was asked to post this patch here.

If the SMBus and I2C block write functions in i2c-dev.h (the version
from lm-sensors, not the kernel) would take const buffer pointers,
this would allow callers to use const data to be sent via SMB/I2C.

Please see the diff below.


Index: include/linux/i2c-dev.h
===================================================================
--- include/linux/i2c-dev.h	(revision 5881)
+++ include/linux/i2c-dev.h	(working copy)
@@ -258,7 +258,7 @@
 }
 
 static inline __s32 i2c_smbus_write_block_data(int file, __u8 command, 
-                                               __u8 length, __u8 *values)
+                                               __u8 length, const __u8 *values)
 {
 	union i2c_smbus_data data;
 	int i;
@@ -296,7 +296,7 @@
 }
 
 static inline __s32 i2c_smbus_write_i2c_block_data(int file, __u8 command,
-                                               __u8 length, __u8 *values)
+                                               __u8 length, const __u8 *values)
 {
 	union i2c_smbus_data data;
 	int i;


Roman

-- 
Roman Fietze              Telemotive AG Buero Muehlhausen
Breitwiesen                             73347 Muehlhausen
Tel.: +49(0)7335/18493-45        http://www.telemotive.de

Re: Const buffer pointers for SMBus/I2C block write functions

[Jean Delvare]

Hi Roman,

Sorry for the late answer.

On Tue, 16 Nov 2010 06:57:10 +0100, Roman Fietze wrote:
> If the SMBus and I2C block write functions in i2c-dev.h (the version
> from lm-sensors, not the kernel) would take const buffer pointers,
> this would allow callers to use const data to be sent via SMB/I2C.

The lm-sensors package no longer includes the "user-space version" of
i2c-dev. It is part of i2c-tools now.

Note that this file is an horror, BTW. It should be turned into a proper
library, to avoid the confusion with the kernel header file. This is on
my to-do list for year 2011.

> Please see the diff below.
> 
> 
> Index: include/linux/i2c-dev.h
> ===================================================================
> --- include/linux/i2c-dev.h	(revision 5881)
> +++ include/linux/i2c-dev.h	(working copy)
> @@ -258,7 +258,7 @@
>  }
>  
>  static inline __s32 i2c_smbus_write_block_data(int file, __u8 command, 
> -                                               __u8 length, __u8 *values)
> +                                               __u8 length, const __u8 *values)
>  {
>  	union i2c_smbus_data data;
>  	int i;
> @@ -296,7 +296,7 @@
>  }
>  
>  static inline __s32 i2c_smbus_write_i2c_block_data(int file, __u8 command,
> -                                               __u8 length, __u8 *values)
> +                                               __u8 length, const __u8 *values)
>  {
>  	union i2c_smbus_data data;
>  	int i;
> 

Yes, this makes sense. Patch applied, thanks.

-- 
Jean Delvare