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-rw-r--r--Documentation/i2c/dev-interface11
1 files changed, 8 insertions, 3 deletions
diff --git a/Documentation/i2c/dev-interface b/Documentation/i2c/dev-interface
index b849ad636583..9dd79123ddd9 100644
--- a/Documentation/i2c/dev-interface
+++ b/Documentation/i2c/dev-interface
@@ -90,12 +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.
@@ -103,8 +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 */
}