DDI_PEEK(9F) Kernel Functions for Drivers DDI_PEEK(9F)


NAME


ddi_peek, ddi_peek8, ddi_peek16, ddi_peek32, ddi_peek64, ddi_peekc,
ddi_peeks, ddi_peekl, ddi_peekd - read a value from a location

SYNOPSIS


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


int ddi_peek8(dev_info_t *dip, int8_t *addr, int8_t *valuep);


int ddi_peek16(dev_info_t *dip, int16_t *addr, int16_t *valuep);


int ddi_peek32(dev_info_t *dip, int32_t *addr, int32_t *valuep);


int ddi_peek64(dev_info_t *dip, int64_t *addr, int64_t *valuep);


INTERFACE LEVEL


Solaris DDI specific (Solaris DDI). The ddi_peekc(), ddi_peeks(),
ddi_peekl(), and ddi_peekd() functions are obsolete. Use, respectively,
ddi_peek8(), ddi_peek16(), ddi_peek32(), and ddi_peek64(), instead.

PARAMETERS


dip
A pointer to the device's dev_info structure.


addr
Virtual address of the location to be examined.


valuep
Pointer to a location to hold the result. If a null pointer is
specified, then the value read from the location will simply be
discarded.


DESCRIPTION


These routines cautiously attempt to read a value from a specified
virtual address, and return the value to the caller, using the parent
nexus driver to assist in the process where necessary.


If the address is not valid, or the value cannot be read without an error
occurring, an error code is returned.


The routines are most useful when first trying to establish the presence
of a device on the system in a driver's probe(9E) or attach(9E) routines.

RETURN VALUES


DDI_SUCCESS
The value at the given virtual address was successfully
read, and if valuep is non-null, *valuep will have been
updated.


DDI_FAILURE
An error occurred while trying to read the location.
*valuep is unchanged.


CONTEXT


These functions can be called from user, interrupt, or kernel context.

EXAMPLES


Example 1: Checking to see that the status register of a device is mapped


into the kernel address space:

if (ddi_peek8(dip, csr, (int8_t *)0) != DDI_SUCCESS) {
cmn_err(CE_WARN, "Status register not mapped");
return (DDI_FAILURE);
}


Example 2: Reading and logging the device type of a particular device:



int
xx_attach(dev_info_t *dip, ddi_attach_cmd_t cmd)
{
...
/* map device registers */
...

if (ddi_peek32(dip, id_addr, &id_value) != DDI_SUCCESS) {
cmn_err(CE_WARN, "%s%d: cannot read device identifier",
ddi_get_name(dip), ddi_get_instance(dip));
goto failure;
} else
cmn_err(CE_CONT, "!%s%d: device type 0x%x\n",
ddi_get_name(dip), ddi_get_instance(dip), id_value);
...
...

ddi_report_dev(dip);
return (DDI_SUCCESS);

failure:
/* free any resources allocated */
...
return (DDI_FAILURE);
}


SEE ALSO


attach(9E), probe(9E), ddi_poke(9F)


Writing Device Drivers

NOTES


The functions described in this manual page previously used symbolic
names which specified their data access size; the function names have
been changed so they now specify a fixed-width data size. See the
following table for the new name equivalents:


+---------------------------+
|Previous Name New Name |
|ddi_peekc ddi_peek8 |
|ddi_peeks ddi_peek16 |
|ddi_peekl ddi_peek32 |
|ddi_peekd ddi_peek64 |
+---------------------------+


January 16, 2006 DDI_PEEK(9F)