ctl function

The ctl function handles a driver-specific devctl() command. The prototype for this function is:

int ctl(
      void *hdl,
      int cmd,
      void *msg,
      int msglen,
      int *nbytes,
      int *info );

The arguments are:

hdl

The handle returned by the init function.

cmd

The device command.

msg

A pointer to the message buffer. The function can change the contents of the buffer.

msglen

The length of the message buffer, in bytes.

nbytes

The number of bytes being returned. This must not be greater than msglen.

info

A pointer to a location where the function can store extra status information returned by devctl().

The function must return:

EOK

Success.

Any other errno value

Failure.