Gain access to a device's registers
Synopsis:
#include <stdint.h>
#include <sys/mman.h>
uintptr_t mmap_device_io( size_t len,
uint64_t io );
Arguments:
- len
- The number of bytes of device I/O memory that you want to access. It can't be 0.
- io
- The address of the area that you want to access.
Library:
libc
Use the -l c option to
qcc
to link against this library.
This library is usually included automatically.
Description:
The mmap_device_io() function maps len bytes of device
I/O memory at io and makes it accessible via the
in*() and
out*() functions in
<hw/inout.h>.
Note:
In order to map physical memory, your process must have the
PROCMGR_AID_MEM_PHYS ability enabled.
For more information, see
procmgr_ability().
Returns:
A handle to the device's I/O memory, or MAP_DEVICE_FAILED if an error occurs
(errno is set).
Errors:
- EINVAL
- Invalid flags type, or len is 0.
- ENOMEM
- The address range requested is outside of the allowed process address range, or
there wasn't enough memory to satisfy the request.
- ENXIO
- The address from io for len bytes is invalid.
- EPERM
- The calling process doesn't have the required permission; see
procmgr_ability().
Classification:
QNX Neutrino
| Safety: |
|
|---|
| Cancellation point |
No |
| Interrupt handler |
No |
| Signal handler |
Yes |
| Thread |
Yes |
Caveats:
On x86 and x86_64, you need I/O privileges to use the result of the mmap_device_io() function:
- The process must have the PROCMGR_AID_IO ability enabled.
For more information, see
procmgr_ability().
- The calling thread must call ThreadCtl() with the
_NTO_TCTL_IO command to establish these privileges.
On ARMv7 and AArch64, these conditions don't apply.