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ddi_copyin(9f)

ddi_copyin(9F)                 Kernel Functions                 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 information
                    about buf.


DESCRIPTION
       This routine is designed for use in driver ioctl(9E) routines for driv‐
       ers that support layered ioctls. ddi_copyin() copies data from a source
       address to a driver buffer. The driver developer must ensure that  ade‐
       quate space is allocated 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 efficient move according to address align‐
       ment.

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 uncorrectable  parity
                  or ECC error occurred.


           o      ADI  version  mismatch;  the  hardware  detected  a mismatch
                  between the version specified for the source address and the
                  actual  in-memory  version.  For  more  information, see the
                  adi(3C) man page.



       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 condition  (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 in Oracle Solaris 11.4

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. For more infor‐
       mation, see M_COPYIN and M_COPYOUT in STREAMS Programming Guide.



Oracle Solaris 11.4               30 Sep 2015                   ddi_copyin(9F)
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