ISA(9) | Kernel Developer's Manual | ISA(9) |
ISA
, isa_intr_alloc
,
isa_intr_establish
,
isa_intr_disestablish
,
isa_intr_evcnt
,
isa_dmamap_create
,
isa_dmamap_destroy
,
isa_dmamem_alloc
,
isa_dmamem_free
,
isa_dmamem_map
,
isa_dmamem_unmap
, isa_malloc
,
isa_free
, isa_dmastart
,
isa_dmaabort
, isa_dmacount
,
isa_dmadone
, isa_dmamaxsize
,
isa_drq_alloc
, isa_drq_free
,
isa_drq_isfree
,
isa_dmacascade
, isa_mappage
—
#include <sys/bus.h>
#include <dev/isa/isareg.h>
#include <dev/isa/isavar.h>
int
isa_intr_alloc
(isa_chipset_tag_t
ic, int mask,
int type,
int *irq);
const struct evcnt *
isa_intr_evcnt
(isa_chipset_tag_t
ic, int irq);
void *
isa_intr_establish
(isa_chipset_tag_t
ic, int irq,
int type,
int level,
int (*handler)(void *),
void *arg);
void
isa_intr_disestablish
(isa_chipset_tag_t
ic, void *ih);
#include
<dev/isa/isadmareg.h>
#include
<dev/isa/isadmavar.h>
int
isa_dmamap_create
(isa_chipset_tag_t
ic, int chan,
bus_size_t size,
int flags);
void
isa_dmamap_destroy
(isa_chipset_tag_t
ic, int chan);
int
isa_dmamem_alloc
(isa_chipset_tag_t
ic, int chan,
bus_size_t size,
bus_addr_t *addrp,
int flags);
void
isa_dmamem_free
(isa_chipset_tag_t
ic, int chan,
bus_addr_t addr,
bus_size_t size);
int
isa_dmamem_map
(isa_chipset_tag_t
ic, int chan,
bus_addr_t addr,
bus_size_t size,
void **kvap,
int flags);
void
isa_dmamem_unmap
(isa_chipset_tag_t
ic, int chan,
void *kva,
size_t size);
void *
isa_malloc
(isa_chipset_tag_t
ic, int chan,
size_t size,
int pool,
int flags);
void
isa_free
(void
*addrp, int
pool);
int
isa_dmastart
(isa_chipset_tag_t
ic, int chan,
bus_addr_t addr,
bus_size_t size,
struct lwp *lwp,
int flags,
int bf);
void
isa_dmaabort
(isa_chipset_tag_t
ic, int chan);
bus_size_t
isa_dmacount
(isa_chipset_tag_t
ic, int chan);
void
isa_dmadone
(isa_chipset_tag_t
ic, int chan);
bus_size_t
isa_dmamaxsize
(isa_chipset_tag_t
ic, int chan);
int
isa_drq_alloc
(isa_chipset_tag_t
ic, int chan);
int
isa_drq_free
(isa_chipset_tag_t
ic, int chan);
int
isa_drq_isfree
(isa_chipset_tag_t
ic, int chan);
int
isa_dmacascade
(isa_chipset_tag_t
ic, int chan);
paddr_t
isa_mappage
(void
*mem, off_t offset,
int prot);
ISA
subsystem provides support
for the ISA bus.
The ISA bus was introduced on the IBM PC/AT. It is an extension to the original bus found on the original IBM PC. The ISA bus is essentially the host bus of the Intel 80286 processor, however the widespread acceptance of the bus as a de facto standard has seen it appear on systems without Intel processors.
The ISA bus has a 16-bit data bus, a 24-bit memory address bus, a 16-bit I/O address bus, and operates at 8MHz. It provides 15 interrupt lines and 8 DMA channels supporting DMA transfers of 64KB or 128KB transfers depending on the width of the channel being used. Historically, some devices only decoded the 10 lowest bits of the I/O address bus, preventing use of the full 16-bit address space.
On newer machines, the ISA bus is no longer connected directly to the host bus, and is usually connected via a PCI-ISA bridge. Either way, the bus looks the same to the device driver.
ISA
bus will make
use of the following data types:
bus_space_tag_t ia_iot; /* isa i/o space tag */ bus_space_tag_t ia_memt; /* isa mem space tag */ bus_dma_tag_t ia_dmat; /* DMA tag */ isa_chipset_tag_t ia_ic; int ia_iobase; /* base i/o address */ int ia_iosize; /* span of ports used */ int ia_maddr; /* physical mem addr */ u_int ia_msize; /* size of memory */ int ia_irq; /* interrupt request */ int ia_drq; /* DMA request */ int ia_drq2; /* second DMA request */ void *ia_aux; /* driver specific */
isa_intr_alloc
(ic,
mask, type,
irq)isa_intr_evcnt
(ic,
irq)isa_intr_establish
(ic,
irq, type,
level, handler,
arg)isa_intr_establish
() with the interrupt number
irq, type type, and level
level. When the interrupt occurs the function
handler is called with argument
arg. Valid values for type
are:
isa_intr_establish
() returns an opaque
handle to an event descriptor if it succeeds, and returns NULL on
failure.
isa_intr_disestablish
(ic,
ih)isa_intr_establish
().isa_drq_alloc
(ic,
chan)isa_dmamap_create
() call. It is an error to start
DMA on a channel that has not been reserved with
isa_drq_alloc
().isa_drq_free
(ic,
chan)isa_dmamap_create
(ic,
chan, size,
flags)bus_dmamap_create
() (see
bus_dma(9)). This function
returns zero on success or an error value on failure.isa_dmamap_destroy
(ic,
chan)isa_dmamem_alloc
(ic,
chan, size,
addrp, flags)bus_dmamem_alloc
() (see
bus_dma(9)). The
bus-address of the memory is returned in addrp. This
function returns zero on success or an error value on failure.isa_dmamem_free
(ic,
chan, addr,
size)isa_dmamem_alloc
() for channel
chan. The bus-address and size of the memory are
specified by addr and size
respectively.isa_dmamem_map
(ic,
chan, addr,
size, kvap,
flags)isa_dmamem_alloc
()) specified by bus-address
addr and of size size into
kernel virtual address space for DMA channel chan.
Valid values for the flags argument are the same as
for bus_dmamem_map
() (see
bus_dma(9)). The kernel
virtual address is returned in kvap. This function
returns zero on success or an error value on failure.isa_dmamem_unmap
(ic,
chan, kva,
size)isa_dmamem_map
()) of size
size for channel chan. The
kernel virtual address space used by the mapping is freed.isa_malloc
(ic,
chan, size,
pool, flags)isa_dmamem_alloc
() and
isa_dmamem_map
(). The argument
pool is a pool to record the memory allocation. This
function returns a pointer to the DMA-safe memory.isa_free
(addrp,
pool)isa_dmamem_unmap
()
and isa_dmamem_free
(). The argument
addrp is the pointer to the DMA-safe memory returned
by isa_malloc
(). The argument
pool is the same as the value passed to
isa_malloc
().isa_dmastart
(ic,
chan, addr,
size, lwp,
flags, bf)The argument bf is the bus-space flags.
Valid values are the same as for
bus_dmamap_load
() (see
bus_dma(9)).
isa_dmaabort
(ic,
chan)isa_dmacount
(ic,
chan)isa_dmadone
(ic,
chan)isa_dmamaxsize
(ic,
chan)isa_drq_isfree
(ic,
chan)isa_dmacascade
(ic,
chan)isa_mappage
(mem,
offset, prot)During the driver attach step, the I/O and memory address spaces should be mapped (see bus_space(9)).
Before allocating resources for DMA transfers on the ISA bus, a
driver should check the maximum allowable DMA transfer size for the DMA
channel using isa_dmamaxsize
().
A DMA map should be created first using
isa_dmamap_create
(). A DMA map describes how DMA
memory is loaded into the DMA controllers. Only DMA-safe memory can be used
for DMA transfers. DMA-safe memory is allocated using
isa_dmamem_alloc
(). The memory allocated by
isa_dmamem_alloc
() must now be mapped into kernel
virtual address space by isa_dmamem_map
() so that it
can be accessed by the driver.
For a DMA transfer from the host to the device, the driver will
fill the DMA memory with the data to be transferred. The DMA-transfer of the
memory is started using isa_dmastart
() with
flags containing DMAMODE_WRITE. When the DMA transfer
is completed, a call to isa_dmadone
() cleans up the
DMA transfer by unloading the memory from the controller.
For a DMA transfer from the device to the host, the DMA-transfer
is started using isa_dmastart
() with
flags containing DMAMODE_READ. When the DMA transfer
is completed, a call to isa_dmadone
() cleans up the
DMA transfer by unloading the memory from the controller. The memory can now
be access by the driver.
When the DMA resources are no longer required they should be
released using isa_dmamem_unmap
(),
isa_dmamem_free
() and
isa_dmamap_destroy
().
ISA
subsystem appeared in
NetBSD 1.2.
isa_intr_establish
() was to
invoke panic
() on failure.
isa_intr_establish
() now returns NULL on failure. Some
old drivers written for the former behaviour discard the return value.
January 29, 2006 | NetBSD 9.2 |