ddi_copyin(9F) Kernel Functions for Drivers ddi_copyin(9F)NAMEddi_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 trans‐
ferred.
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 VALUESddi_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.
·
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.
CONTEXTddi_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, ®_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 ALSOioctl(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.
ddi_copyin() should not be used from a streams driver. See M_COPYIN and
M_COPYOUT in STREAMS Programming Guide.
SunOS 5.10 19 Apr 2000 ddi_copyin(9F)
