DDI_COPYIN(9F) Kernel Functions for Drivers DDI_COPYIN(9F)
ddi_copyin - copy data to a driver buffer
#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);
illumos DDI specific (illumos DDI).
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.
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 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 alignment.
ddi_copyin() returns 0, indicating a successful copy. It returns -1
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_copyin() can be called from user or kernel context only.
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 }
ioctl(9E), bcopy(9F), copyin(9F), copyout(9F), ddi_copyout(9F),
uiomove(9F)
Writing Device Drivers
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.
April 19, 2000 DDI_COPYIN(9F)
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(const void *buf, void *driverbuf, size_t cn, int flags);
INTERFACE LEVEL
illumos DDI specific (illumos DDI).
PARAMETERS
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.
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 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 alignment.
RETURN VALUES
ddi_copyin() returns 0, indicating a successful copy. It returns -1
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.
CONTEXT
ddi_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 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.
ddi_copyin() should not be used from a streams driver. See M_COPYIN
and M_COPYOUT in STREAMS Programming Guide.
April 19, 2000 DDI_COPYIN(9F)