X-Git-Url: http://pilppa.org/gitweb/gitweb.cgi?a=blobdiff_plain;f=Documentation%2Fi2c%2Fdev-interface;h=9dd79123ddd9949de863a0c2c20e98f99269a8c4;hb=95b7cf930defdeb639c0b0d6220be738402c36c7;hp=a78ea62506ee1e17976dcad132b386ca0418bb8c;hpb=a68e2f4895070f3a449bfe5ae1174b73cc900642;p=linux-2.6-omap-h63xx.git

diff --git a/Documentation/i2c/dev-interface b/Documentation/i2c/dev-interface
index a78ea62506e..9dd79123ddd 100644
--- a/Documentation/i2c/dev-interface
+++ b/Documentation/i2c/dev-interface
@@ -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
@@ -87,12 +90,15 @@ ioctl(file,I2C_SLAVE,long addr)
 
 ioctl(file,I2C_TENBIT,long select)
   Selects ten bit addresses if select not equals 0, selects normal 7 bit
-  addresses if select equals 0. Default 0.
+  addresses if select equals 0. Default 0.  This request is only valid
+  if the adapter has I2C_FUNC_10BIT_ADDR.
 
 ioctl(file,I2C_PEC,long select)
   Selects SMBus PEC (packet error checking) generation and verification
   if select not equals 0, disables if select equals 0. Default 0.
-  Used only for SMBus transactions.
+  Used only for SMBus transactions.  This request only has an effect if the
+  the adapter has I2C_FUNC_SMBUS_PEC; it is still safe if not, it just
+  doesn't have any effect.
 
 ioctl(file,I2C_FUNCS,unsigned long *funcs)
   Gets the adapter functionality and puts it in *funcs.
@@ -100,8 +106,10 @@ ioctl(file,I2C_FUNCS,unsigned long *funcs)
 ioctl(file,I2C_RDWR,struct i2c_rdwr_ioctl_data *msgset)
 
   Do combined read/write transaction without stop in between.
-  The argument is a pointer to a struct i2c_rdwr_ioctl_data {
+  Only valid if the adapter has I2C_FUNC_I2C.  The argument is
+  a pointer to a
 
+  struct i2c_rdwr_ioctl_data {
       struct i2c_msg *msgs;  /* ptr to array of simple messages */
       int nmsgs;             /* number of messages to exchange */
   }