ddi_copyout man page on SmartOS

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       ddi_copyout - copy data from a driver

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

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

       Solaris DDI specific (Solaris DDI).

		    Source address in the driver from which the data is trans‐

		    Destination address to which the data is transferred.

		    Number of bytes to copy.

		    Set of flag bits that provide  address  space  information
		    about buf.

       This routine is designed for use in driver ioctl(9E) routines for driv‐
       ers that support layered	 ioctls.  ddi_copyout()	 copies	 data  from  a
       driver buffer to a destination address, buf.

       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_copyout() behaves like bcopy(9F).  Otherwise,	buf is
       interpreted as a user buffer address, and  ddi_copyout()	 behaves  like

       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 algorithm according to
       address alignment.

       Under normal conditions, 0 is returned to indicate a  successful	 copy.
       Otherwise, −1 is returned 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.

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

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

       Example 1 ddi_copyout() example

       A driver ioctl(9E) routine (line 12) can be used to get or  set	device
       attributes  or  registers.  In  the XX_GETREGS condition (line 25), the
       driver copies the current device register values to another data	 area.
       If the specified argument contains an invalid address, an error code is

	 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 registers to arg */
	 26	       mutex_enter(&sp->reg_mutex);
	 27	       /*
	 28		* Copy data from device registers to
	 29		* temporary device register buffer
	 30		* e.g. reg_buf.control = rp->control;
	 31		*/
	 32	       mutex_exit(&sp->reg_mutex);
	 33	       if (ddi_copyout(®_buf, arg,
	 34		   sizeof (struct device), mode) != 0) {
	 35		       return (EFAULT);
	 36	       }

	 37	       break;
	 38	 }
	 39  }

       ioctl(9E),   bcopy(9F),	 copyin(9F),   copyout(9F),    ddi_copyin(9F),

       Writing Device Drivers

       The  value  of  the  flags  argument  to ddi_copyout() 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_copyout() should not be used from a streams	driver.	 See  M_COPYIN
       and M_COPYOUT in STREAMS Programming Guide.

				 Apr 19, 2000		       DDI_COPYOUT(9F)

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