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

ARGUMENTS

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.

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_copyin( ) copies data from a source address to a driver buffer. The driver developer must ensure that adequate space is allocated for the destination address.

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_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 alignment.

RETURN VALUES

ddi_copyin( ) returns 0 ,indicating a successful copy. It returns -1 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.

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_SETREGS:

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

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

CONTEXT

ddi_copyin( ) can be called from user context only.

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.