Kernel Functions for Drivers ddicopyout(9F)
NAME
ddicopyout - copy data from a driver
SYNOPSIS
#include
#include
#include
int ddicopyout(const void *driverbuf, void *buf, sizet cn, int flags);
INTERFACE LEVEL
Solaris DI specific (Solaris DI).
PARAMETERS
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.
DESCRIPTION
This routine is designed for use in driver ioctl(9E) rou-
tines for drivers that support layered ioctls. ddicopyout()
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 ddicopyout() behaves like
bcopy(9F). Otherwise, buf is interpreted as a user buffer
address, and ddicopyout() 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 effi-
cient move algorithm according to address alignment.
SunOS 5.11 Last change: 19 Apr 2000 1
Kernel Functions for Drivers ddicopyout(9F)
RETURN VALUES
Under normal conditions, 0 is returned to indicate a suc-
cessful copy. Otherwise, -1 is returned if one of the fol-
lowing 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 EC error occurred.
If -1 is returned to the caller, driver entry point routines
should return EFAULT.
CONTEXT
ddicopyout() can be called from user or kernel context
only.
EXAMPLES
Example 1 ddicopyout() example
A driver ioctl(9E) routine (line 12) can be used to get or
set device attributes or registers. In the XGETREGS condi-
tion (line 25), the driver copies the current device regis-
ter values to another data area. 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 recvchar; /* receive character from device */
5 short xmitchar; /* transmit character to device */
6 };
7 struct devicestate {
8 volatile struct device *regsp; /* pointer to device registers */
9 kmutext regmutex; /* protect device registers */
. . .
10 };
11 static void *statep; /* for soft state routines */
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Kernel Functions for Drivers ddicopyout(9F)
12 xxioctl(devt dev, int cmd, int arg, int mode,
13 credt *credp, int *rvalp)
14 {
15 struct devicestate *sp;
16 volatile struct device *rp;
17 struct device regbuf; /* temporary buffer for registers */
18 int instance;
19 instance = getminor(dev);
20 sp = ddigetsoftstate(statep, instance);
21 if (sp == NUL)
22 return (ENXIO);
23 rp = sp->regsp;
. . .
24 switch (cmd) {
25 case XGETREGS: /* copy registers to arg */
26 mutexenter(&sp->regmutex);
27 /*
28 * Copy data from device registers to
29 * temporary device register buffer
30 * e.g. regbuf.control = rp->control;
31 */
32 mutexexit(&sp->regmutex);
33 if (ddicopyout(®buf, arg,
34 sizeof (struct device), mode) != 0) {
35 return (EFAULT);
36 }
37 break;
38 }
39 }
SEE ALSO
ioctl(9E), bcopy(9F), copyin(9F), copyout(9F),
ddicopyin(9F), uiomove(9F)
Writing Device Drivers
NOTES
The value of the flags argument to ddicopyout() should be
passed through directly from the mode argument of ioctl()
untranslated.
Driver defined locks should not be held across calls to this
function.
SunOS 5.11 Last change: 19 Apr 2000 3
Kernel Functions for Drivers ddicopyout(9F)
ddicopyout() should not be used from a streams driver. See
MCOPYIN and MCOPYOUT in STREAMS Programming Guide.
SunOS 5.11 Last change: 19 Apr 2000 4
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