ddi_copyin(9F)

NAME

     ddi_copyin - copy data to a driver buffer

SYNOPSIS

     #include <sys/types.h>
     #include <sys/ddi.h>
     #include <sys/sunddi.h>

     int ddi_copyin(const void *buf, void *driverbuf, size_t  cn,
     int flags);

INTERFACE LEVEL

     Solaris DDI specific (Solaris DDI).

PARAMETERS

     buf   Source address from which data is transferred.

     driverbuf
           Driver  destination   address   to   which   data   is
           transferred.

     cn    Number of bytes transferred.

     flags Set of flag bits that provide address  space  informa-
           tion about buf.

DESCRIPTION

     This routine is designed for use in  driver  ioctl(9E)  rou-
     tines  for drivers that support layered ioctls. ddi_copyin()
     copies data from a source address to a driver  buffer.   The
     driver  developer  must  ensure that adequate space is allo-
     cated for the destination address.

     The flags argument determines the address space  information
     about  buf.  If the FKIOCTL flag is set, this indicates that
     buf is a kernel  address,  and   ddi_copyin()  behaves  like
     bcopy(9F).  Otherwise,  buf  is interpreted as a user buffer
     address, and ddi_copyin() behaves like copyin(9F).

     Addresses that are word-aligned are moved most  efficiently.
     However,  the  driver  developer  is  not  obliged to ensure
     alignment.  This function automatically finds the most effi-
     cient move according to address alignment.

RETURN VALUES

     ddi_copyin() returns 0, indicating  a  successful  copy.  It
     returns -1 if one of the following occurs:

        o  Paging fault; the driver tried to  access  a  page  of
           memory for which it did not have read or write access.

        o  Invalid user address, such as a  user  area  or  stack
           area.

        o  Invalid address that would have resulted in data being
           copied into the user block.

        o  Hardware fault; a hardware error prevented  access  to
           the  specified user memory. For example, an uncorrect-
           able parity or ECC error occurred.

     If -1 is returned to the caller, driver entry point routines
     should return EFAULT.

CONTEXT

     ddi_copyin() can be called from user or kernel context only.

EXAMPLES

     Example 1: ddi_copyin() example

     A driver ioctl(9E) routine (line 12) can be used to  get  or
     set  device attributes or registers. For the XX_SETREGS con-
     dition (line 25), the driver copies the user data in arg  to
     the device registers.  If the specified argument contains an
     invalid address, an error code is returned.

      1  struct device  {     /* layout of physical device registers  */
      2     int      control; /* physical device control word  */
      3     int      status;  /* physical device status word   */
      4     short    recv_char;    /* receive character from device */
      5     short    xmit_char;    /* transmit character to device  */
      6  };
      7  struct device_state {
      8     volatile struct device *regsp;   /* pointer to device registers */
      9     kmutex_t reg_mutex;              /* protect device registers */
            . . .
     10  };

     11  static void *statep; /* for soft state routines */

     12  xxioctl(dev_t dev, int cmd, int arg, int mode,
     13      cred_t *cred_p, int *rval_p)
     14  {
     15      struct device_state *sp;
     16      volatile struct device *rp;
     17      struct device reg_buf;     /* temporary buffer for registers */
     18      int instance;

     19      instance = getminor(dev);
     20      sp = ddi_get_soft_state(statep, instance);
     21      if (sp == NULL)
     22          return (ENXIO);
     23      rp = sp->regsp;
             . . .

     24      switch (cmd)  {

     25      case XX_GETREGS: /* copy data to temp. regs. buf */
     26            if (ddi_copyin(arg, &reg_buf,
     27                sizeof (struct device), mode) != 0) {
     28                    return (EFAULT);
     29            }

     30            mutex_enter(&sp->reg_mutex);
     31            /*
     32             * Copy data from temporary device register
     33             * buffer to device registers.
     34             * e.g. rp->control = reg_buf.control;
     35             */
     36            mutex_exit(&sp->reg_mutex);

     37            break;
     38      }
     39  }

SEE ALSO

     ioctl(9E),     bcopy(9F),      copyin(9F),      copyout(9F),
     ddi_copyout(9F), uiomove(9F)

     Writing Device Drivers

NOTES

     The value of the flags argument to  ddi_copyin()  should  be
     passed  through  directly  from the mode argument of ioctl()
     untranslated.

     Driver defined locks should not be held across calls to this
     function.

     ddi_copyin() should not be used from a streams  driver.  See
     M_COPYIN and M_COPYOUT in STREAMS Programming Guide.