NAME

ddi_copyout - copy data from a driver

SYNOPSIS

#include <sys/types.h>

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

int ddi_copyout(caddr_t driverbuf, caddr_t buf, size_t cn, int flags);

ARGUMENTS

driverbuf

Source address in the driver from which the data is transferred.

buf

Destination address to which the data is transferred.

cn

Number of bytes to copy.

flags

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

INTERFACE LEVEL

Solaris DDI specific (Solaris DDI).

DESCRIPTION

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

The flags argument is used to determine 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 copyout(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 algorithm according to address alignment.

RETURN VALUES

Under normal conditions a 0 is returned to indicate a successful copy. Otherwise, a -1 is returned if one of the following occurs:

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

invalid user address, such as a user area or stack area

invalid address that would have resulted in data being copied into the user block

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

CONTEXT

ddi_copyout( ) can be called from user context only.

EXAMPLES

A driver ioctl(9E) routine (line 11) can be used to get or set device attributes or registers. In the XX_GETREGS condition (line 24), the driver copies the current device register values to another data area (line 25). 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 };

10 static void ** statep;

/** for soft state routines ** /

11 xxioctl(dev_t dev, int cmd, int arg, int mode,
12   cred_t ** cred_p,int ** rval_p)
13 {
14   struct device_state ** sp;
15   volatile struct device ** rp;
16   int instance;

17

instance = getminor(dev) >> 4;

18   sp = ddi_get_soft_state(statep, instance);
19   if (sp == NULL)
20     return (ENXIO);
21   rp = sp->regsp;

. . .

22   switch (cmd) {

24

case XX_GETREGS:

/** copy device regs. to caller ** /

25      if (ddi_copyout((caddr_t)rp, (caddr_t)arg,
26         sizeof (struct device), mode) != 0) {
27           return (EFAULT);
28      }

SEE ALSO

bcopy(9F), copyin(9F), copyout(9F), ddi_copyin(9F), uiomove(9F)

Writing Device Drivers

NOTES

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.