'\" te
.\"  Copyright (c) 2006, Sun Microsystems, Inc.  All Rights Reserved
.TH ddi_peek 9F "16 Jan 2006" "SunOS 5.11" "Kernel Functions for Drivers"
.SH 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
.SH SYNOPSIS
.LP
.nf
#include <sys/ddi.h>
#include <sys/sunddi.h>

\fBint\fR \fBddi_peek8\fR(\fBdev_info_t\fR \fI*dip\fR, \fBint8_t\fR \fI*addr\fR, \fBint8_t\fR \fI*valuep\fR);
.fi

.LP
.nf
\fBint\fR \fBddi_peek16\fR(\fBdev_info_t\fR \fI*dip\fR, \fBint16_t\fR \fI*addr\fR, \fBint16_t\fR \fI*valuep\fR);
.fi

.LP
.nf
\fBint\fR \fBddi_peek32\fR(\fBdev_info_t\fR \fI*dip\fR, \fBint32_t\fR \fI*addr\fR, \fBint32_t\fR \fI*valuep\fR);
.fi

.LP
.nf
\fBint\fR \fBddi_peek64\fR(\fBdev_info_t\fR \fI*dip\fR, \fBint64_t\fR \fI*addr\fR, \fBint64_t\fR \fI*valuep\fR);
.fi

.SH INTERFACE LEVEL
.sp
.LP
Solaris DDI specific (Solaris DDI). The \fBddi_peekc()\fR, \fBddi_peeks()\fR, \fBddi_peekl()\fR, and \fBddi_peekd()\fR functions are obsolete. Use, respectively, \fBddi_peek8()\fR, \fBddi_peek16()\fR, \fBddi_peek32()\fR, and \fBddi_peek64()\fR, instead.
.SH PARAMETERS
.sp
.ne 2
.mk
.na
\fB\fIdip\fR\fR
.ad
.RS 10n
.rt  
A pointer to the device's \fBdev_info\fR structure.
.RE

.sp
.ne 2
.mk
.na
\fB\fIaddr\fR\fR
.ad
.RS 10n
.rt  
Virtual address of the location to be examined.
.RE

.sp
.ne 2
.mk
.na
\fB\fIvaluep\fR\fR
.ad
.RS 10n
.rt  
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.
.RE

.SH DESCRIPTION
.sp
.LP
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.
.sp
.LP
If the address is not valid, or the value cannot be read without an error occurring, an error code is returned.
.sp
.LP
The routines are most useful when first trying to establish the presence of a device on the system in a driver's \fBprobe\fR(9E) or \fBattach\fR(9E) routines.
.SH RETURN VALUES
.sp
.ne 2
.mk
.na
\fB\fBDDI_SUCCESS\fR\fR
.ad
.RS 15n
.rt  
The value at the given virtual address was successfully read, and if \fIvaluep\fR is non-null, \fI*valuep\fR will have been updated.
.RE

.sp
.ne 2
.mk
.na
\fB\fBDDI_FAILURE\fR\fR
.ad
.RS 15n
.rt  
An error occurred while trying to read the location. \fI*valuep\fR is unchanged.
.RE

.SH CONTEXT
.sp
.LP
These functions can be called from user, interrupt, or kernel context.
.SH EXAMPLES
.LP
\fBExample 1 \fRChecking to see that the status register of a device is mapped into the kernel address space:
.sp
.in +2
.nf
if (ddi_peek8(dip, csr, (int8_t *)0) != DDI_SUCCESS) {
        cmn_err(CE_WARN, "Status register not mapped");
        return (DDI_FAILURE);
}
.fi
.in -2

.LP
\fBExample 2 \fRReading and logging the device type of a particular device:
.sp
.in +2
.nf
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);
}
.fi
.in -2

.SH SEE ALSO
.sp
.LP
\fBattach\fR(9E), \fBprobe\fR(9E), \fBddi_poke\fR(9F) 
.sp
.LP
\fIWriting Device Drivers for Oracle Solaris 11.2\fR 
.SH NOTES
.sp
.LP
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:
.sp

.sp
.TS
tab() box;
lw(2.75i) lw(2.75i) 
lw(2.75i) lw(2.75i) 
.
\fBPrevious Name\fR\fBNew Name\fR
\fBddi_peekc\fR\fBddi_peek8\fR
\fBddi_peeks\fR\fBddi_peek16\fR
\fBddi_peekl\fR\fBddi_peek32\fR
\fBddi_peekd\fR\fBddi_peek64\fR
.TE