XIO_PACK(D3)XIO_PACK(D3)NAMEXIO_PACK - build a packed XIO address
XIO_PACKED - check if XIO address is packed
XIO_PORT - extract port from packed XIO address
XIO_ADDR - extract offset from packed XIO address
XIO_NOWHERE - nonexistent XIO target
SYNOPSIS
#include <sys/xtalk/xtalk.h>
/*
** These are really macros, but
** if they were functions:
*/
iopaddr_t
XIO_PACK(xwidgetnum_t port, iopaddr_t offset)
int
XIO_PACKED(iopaddr_t xaddr)
xwidgetnum_t
XIO_PORT(iopaddr_t xaddr)
iopaddr_t
XIO_ADDR(iopaddr_t xaddr)
iopaddr_t XIO_NOWHERE;
Arguments
offset is an appropriate 48-bit XIO address (offset).
port is a 4-bit XIO target port number.
xaddr is
DESCRIPTIONXIO_PACK() merges an XIO target port number with the XIO target address
offset into a single number that can be efficiently passed and returned.
XIO_PACKED() returns nonzero if the parameter is a packed XIO address, or
zero if the parameter represents an offset, and the XIO target must be
inferred by the device driver (which should use its assigned XIO "master"
port).
XIO_PORT() extracts the target port number from a packed address.
XIO_ADDR() extracts the target address from a packed address.
XIO_NOWHERE is a constant containing a packed XIO address that represents
an impossible DMA target.
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XIO_PACK(D3)XIO_PACK(D3)
The most common use of packed addresses is when XIO DMA target
translation results are returned, and it is expected that only rarely
will packed addresses actually be used, since nearly all DMA is directed
via the device's assigned master port to system memory. However, it is
advised that all drivers using xtalk_dma services watch for and handle
packed addresses.
There are a number of objects in the system which the CPU can directly
access, but which devices can not access over the XIO bus. While it is
rare to see XIO_PACKED addresses, it should be even more rare to see
XIO_NOWHERE; this represents either a programming error in the device
driver, or an attempt by a user to initiate DMA somewhere silly.
EXAMPLES
The following is a contrived example of some interrupt code servicing a
simple DMA engine on an XIO card.
xaddr = xtalk_dmamap_addr(dmamap, paddr, size);
if (XIO_PACKED(xaddr)) {
if (xaddr == XIO_NOWHERE)
goto fail;
xport = XIO_PORT(xaddr);
xaddr = XIO_ADDR(xaddr);
} else
xport = soft->master_port;
regs->xaddr = xaddr;
regs->xport = port;
regs->bytes = size;
regs->command = DMA_GO;
NOTES
Backward compatibility dictates the format of the unpacked address: it
must be a bare offset, and implicitly refers to a particular device's XIO
master device, assigned previously. The most convenient encoding to use
for packed XIO addresses results in packed addresses to IO port 0 being
undifferentiable from unpacked values. This results in the limitation
that setting up peer-to-peer DMA to XIO widget 0 is not possible; this
restriction is acceptable, since the device answering at XIO widget 0 is
not a reasonable DMA target.
SEE ALSOxtalk_dma(D3)
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