Manpages

NAME

mmap − check virtual mapping for memory mapped device

SYNOPSIS

#include <sys/types.h>
#include <sys/cred.h>
#include <sys/mman.h>
#include <sys/ddi.h>

int prefixmmap(dev_t dev, off_t off, int prot);

INTERFACE LEVEL

Architecture independent level 1 (DDI/DKI).

PARAMETERS

PROT_READ

Read access will be granted.

PROT_WRITE

Write access will be granted.

PROT_EXEC

Execute access will be granted.

PROT_USER

User-level access will be granted.

PROT_ALL

All access will be granted.

DESCRIPTION

Future releases of Solaris will provide this function for binary and source compatibility. However, for increased functionality, use devmap(9E) instead. See devmap(9E) for details.

The mmap() entry point is a required entry point for character drivers supporting memory-mapped devices. A memory mapped device has memory that can be mapped into a process’s address space. The mmap(2) system call, when applied to a character special file, allows this device memory to be mapped into user space for direct access by the user application.

The mmap() entry point is called as a result of an mmap(2) system call, and also as a result of a page fault. mmap() is called to translate the offset off in device memory to the corresponding physical page frame number.

The mmap() entry point checks if the offset off is within the range of pages exported by the device. For example, a device that has 512 bytes of memory that can be mapped into user space should not support offsets greater than 512. If the offset does not exist, then -1 is returned. If the offset does exist, mmap() returns the value returned by hat_getkpfnum(9F) for the physical page in device memory containing the offset off.

hat_getkpfnum(9F) accepts a kernel virtual address as an argument. A kernel virtual address can be obtained by calling ddi_regs_map_setup(9F) in the driver’s attach(9E) routine. The corresponding
ddi_regs_map_free(9F) call can be made in the driver’s detach(9E) routine. Refer to The mmap() Entry Point below for more information.

struct reg {
             uint8_t     csr;
             uint8_t     data;
};
struct xxstate {
        ...
             struct reg  *regp
        ...
};

struct xxstate *xsp;
...

static int
xxmmap(dev_t dev, off_t off, int prot)
{
        int         instance;
        struct xxstate *xsp;

         /* No write access */
        if (prot & PROT_WRITE)
                      return (-1);

        instance = getminor(dev);
        xsp = ddi_get_soft_state(statep, instance);
        if (xsp == NULL)
                      return (-1);


        /* check for a valid offset */
            if ( off is invalid )
                      return (-1);
            return (hat_getkpfnum (xsp->regp->csr + off));
}