man/man9f/ddi_peek.9f

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 DDI_PEEK 9F "Jan 16, 2006"
 NAME
ddi_peek, ddi_peek8, ddi_peek16, ddi_peek32, ddi_peek64
- 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
illumos DDI specific (illumos 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\en",
 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