ca.tex

linux TV 源码

\devsec{DVB CA Device}

The DVB CA device controls the conditional access hardware.
It can be accessed through \texttt{/dev/dvb/adapter0/ca0}.
Data types and and ioctl definitions can be accessed by including
\texttt{linux/dvb/ca.h} in your application.


\devsubsec{CA Data Types}

\devsubsubsec{ca\_slot\_info\_t}
\label{caslotinfo}

\begin{verbatim}
/* slot interface types and info */

typedef struct ca_slot_info_s {
        int num;               /* slot number */

        int type;           /* CA interface this slot supports */
#define CA_CI            1  /* CI high level interface */
#define CA_CI_LINK       2  /* CI link layer level interface */
#define CA_CI_PHYS       4  /* CI physical layer level interface */
#define CA_SC          128  /* simple smart card interface */

        unsigned int flags;
#define CA_CI_MODULE_PRESENT 1 /* module (or card) inserted */
#define CA_CI_MODULE_READY   2
} ca_slot_info_t;
\end{verbatim}

\devsubsubsec{ca\_descr\_info\_t}
\label{cadescrinfo}

\begin{verbatim}
typedef struct ca_descr_info_s {
        unsigned int num;  /* number of available descramblers (keys) */ 
        unsigned int type; /* type of supported scrambling system */
#define CA_ECD           1
#define CA_NDS           2
#define CA_DSS           4
} ca_descr_info_t;
\end{verbatim}

\devsubsubsec{ca\_cap\_t}
\label{cacap}

\begin{verbatim}
typedef struct ca_cap_s {
        unsigned int slot_num;  /* total number of CA card and module slots */
        unsigned int slot_type; /* OR of all supported types */
        unsigned int descr_num; /* total number of descrambler slots (keys) */
        unsigned int descr_type;/* OR of all supported types */
} ca_cap_t;
\end{verbatim}


\devsubsubsec{ca\_msg\_t}
\label{camsg}

\begin{verbatim}
/* a message to/from a CI-CAM */
typedef struct ca_msg_s {   
        unsigned int index;         
        unsigned int type;
        unsigned int length;
        unsigned char msg[256];
} ca_msg_t;
\end{verbatim}


\devsubsubsec{ca\_descr\_t}
\label{cadescr}

\begin{verbatim}
typedef struct ca_descr_s {
        unsigned int index;    
        unsigned int parity;
        unsigned char cw[8];
} ca_descr_t;
\end{verbatim}

\clearpage

\devsubsec{CA Function Calls}

\function{open()}{
  int open(const char *deviceName, int flags);}{
  This system call opens a named ca device (e.g. /dev/ost/ca) 
  for subsequent use.
  
  When an open() call has succeeded, the device will be ready for use.
  The significance of blocking or non-blocking mode is described in 
  the documentation for functions where there is a difference. 
  It does not affect the semantics of the open() call itself. 
  A device opened in blocking mode can later be put into non-blocking mode 
  (and vice versa) using the F\_SETFL command of the fcntl system
  call.  
  This is a standard system call, documented in the Linux manual 
  page for fcntl.
  Only one user can open the CA Device in O\_RDWR mode. All other attempts to
  open the device in this mode will fail, and an error code will be returned.
  }{
  const char *deviceName & Name of specific video device.\\
  int flags & A bit-wise OR of the following flags:\\
            & \hspace{1em} O\_RDONLY read-only access\\
            & \hspace{1em} O\_RDWR read/write access\\
            & \hspace{1em} O\_NONBLOCK open in non-blocking mode \\
            & \hspace{1em} (blocking mode is the default)\\
  }{
  ENODEV    & Device driver not loaded/available.\\
  EINTERNAL & Internal error.\\
  EBUSY     & Device or resource busy.\\
  EINVAL    & Invalid argument.\\
}

\function{close()}{
  int close(int fd);}{
  This system call closes a previously opened audio device.
  }{
  int fd & File descriptor returned by a previous call to open().\\
  }{
  EBADF & fd is not a valid open file descriptor.\\
}

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