1.\" $NetBSD: isa.9,v 1.6 2002/02/13 08:18:42 ross Exp $ 2.\" 3.\" Copyright (c) 2001 The NetBSD Foundation, Inc. 4.\" All rights reserved. 5.\" 6.\" This code is derived from software contributed to The NetBSD Foundation 7.\" by Gregory McGarry. 8.\" 9.\" Redistribution and use in source and binary forms, with or without 10.\" modification, are permitted provided that the following conditions 11.\" are met: 12.\" 1. Redistributions of source code must retain the above copyright 13.\" notice, this list of conditions and the following disclaimer. 14.\" 2. Redistributions in binary form must reproduce the above copyright 15.\" notice, this list of conditions and the following disclaimer in the 16.\" documentation and/or other materials provided with the distribution. 17.\" 3. All advertising materials mentioning features or use of this software 18.\" must display the following acknowledgement: 19.\" This product includes software developed by the NetBSD 20.\" Foundation, Inc. and its contributors. 21.\" 4. Neither the name of The NetBSD Foundation nor the names of its 22.\" contributors may be used to endorse or promote products derived 23.\" from this software without specific prior written permission. 24.\" 25.\" THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 26.\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 27.\" TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 28.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 29.\" BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 30.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 31.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 32.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 33.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 34.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 35.\" POSSIBILITY OF SUCH DAMAGE. 36.\" 37.Dd June 19, 2001 38.Dt ISA 9 39.Os 40.Sh NAME 41.Nm ISA , 42.Nm isa_intr_alloc , 43.Nm isa_intr_establish , 44.Nm isa_intr_disestablish , 45.Nm isa_intr_evcnt , 46.Nm isa_dmamap_create , 47.Nm isa_dmamap_destroy , 48.Nm isa_dmamem_alloc , 49.Nm isa_dmamem_free , 50.Nm isa_dmamem_map , 51.Nm isa_dmamem_unmap , 52.Nm isa_malloc , 53.Nm isa_free , 54.Nm isa_dmastart , 55.Nm isa_dmaabort , 56.Nm isa_dmacount , 57.Nm isa_dmadone , 58.Nm isa_dmamaxsize , 59.Nm isa_drq_isfree , 60.Nm isa_dmacascade , 61.Nm isa_mappage 62.Nd Industry-standard Architecture 63.Sh SYNOPSIS 64.Fd #include \*[Lt]machine/bus.h\*[Gt] 65.Fd #include \*[Lt]dev/isa/isareg.h\*[Gt] 66.Fd #include \*[Lt]dev/isa/isavar.h\*[Gt] 67.Ft int 68.Fn isa_intr_alloc "isa_chipset_tag_t ic" "int mask" "int type" \ 69"int *irq" 70.Ft const struct evcnt * 71.Fn isa_intr_evcnt "isa_chipset_tag_t ic" "int irq" 72.Ft void * 73.Fn isa_intr_establish "isa_chipset_tag_t ic" "int irq" "int type" \ 74"int level" "int (*handler)(void *)" "void *arg" 75.Ft void 76.Fn isa_intr_disestablish "isa_chipset_tag_t ic" "void *ih" 77.Fd #include \*[Lt]dev/isa/isadmareg.h\*[Gt] 78.Fd #include \*[Lt]dev/isa/isadmavar.h\*[Gt] 79.Ft int 80.Fn isa_dmamap_create "isa_chipset_tag_t ic" "int chan" "bus_size_t size" \ 81"int flags" 82.Ft void 83.Fn isa_dmamap_destroy "isa_chipset_tag_t ic" "int chan" 84.Ft int 85.Fn isa_dmamem_alloc "isa_chipset_tag_t ic" "int chan" "bus_size_t size" \ 86"bus_addr_t *addrp" "int flags" 87.Ft void 88.Fn isa_dmamem_free "isa_chipset_tag_t ic" "int chan" "bus_addr_t addr" \ 89"bus_size_t size" 90.Ft int 91.Fn isa_dmamem_map "isa_chipset_tag_t ic" "int chan" "bus_addr_t addr" \ 92"bus_size_t size" "caddr_t *kvap" "int flags" 93.Ft void 94.Fn isa_dmamem_unmap "isa_chipset_tag_t ic" "int chan" "caddr_t kva" \ 95"size_t size" 96.Ft void * 97.Fn isa_malloc "isa_chipset_tag_t ic" "int chan" "size_t size" \ 98"int pool" "int flags" 99.Ft void 100.Fn isa_free "void *addrp" "int pool" 101.Ft int 102.Fn isa_dmastart "isa_chipset_tag_t ic" "int chan" "bus_addr_t addr" \ 103"bus_size_t size" "struct proc *proc" "int flags" "int bf" 104.Ft void 105.Fn isa_dmaabort "isa_chipset_tag_t ic" "int chan" 106.Ft bus_size_t 107.Fn isa_dmacount "isa_chipset_tag_t ic" "int chan" 108.Ft void 109.Fn isa_dmadone "isa_chipset_tag_t ic" "int chan" 110.Ft bus_size_t 111.Fn isa_dmamaxsize "isa_chipset_tag_t ic" "int chan" 112.Ft int 113.Fn isa_drq_isfree "isa_chipset_tag_t ic" "int chan" 114.Ft int 115.Fn isa_dmacascade "isa_chipset_tag_t ic" "int chan" 116.Ft paddr_t 117.Fn isa_mappage "void *mem" "off_t offset" "int prot" 118.Sh DESCRIPTION 119The machine-independent 120.Nm 121subsystem provides support for the ISA bus. 122.Pp 123The ISA bus was introduced on the IBM PC/AT. It is an extension to 124the original bus found on the original IBM PC. The ISA bus is 125essentially the host bus of the Intel 80286 processor, however the 126widespread acceptance of the bus as a defacto standard has seen it 127appear on systems without Intel processors. 128.Pp 129The ISA bus has a 16-bit data bus, a 24-bit memory address bus, a 13016-bit I/O address bus, and operates at 8MHz. It provides 15 131interrupt lines and 8 DMA channels supporting DMA transfers of 64KB or 132128KB transfers depending on the width of the channel being 133used. Historically, some devices only decoded the 10 lowest bits of 134the I/O address bus, preventing use of the full 16-bit address space. 135.Pp 136On newer machines, the ISA bus is no longer connected directly to the 137host bus, and is usually connected via a PCI-ISA bridge. Either way, 138the bus looks the same to the device driver. 139.Sh DATA TYPES 140Drivers for devices attached to the 141.Nm 142bus will make use of the following data types: 143.Bl -tag -width compact 144.It Fa isa_chipset_tag_t 145Chipset tag for the ISA bus. 146.It Fa struct isa_attach_args 147Location hints for devices are recorded in this structure. It 148contains the following members: 149.Bd -literal 150 bus_space_tag_t ia_iot; /* isa i/o space tag */ 151 bus_space_tag_t ia_memt; /* isa mem space tag */ 152 bus_dma_tag_t ia_dmat; /* DMA tag */ 153 isa_chipset_tag_t ia_ic; 154 int ia_iobase; /* base i/o address */ 155 int ia_iosize; /* span of ports used */ 156 int ia_maddr; /* physical mem addr */ 157 u_int ia_msize; /* size of memory */ 158 int ia_irq; /* interrupt request */ 159 int ia_drq; /* DMA request */ 160 int ia_drq2; /* second DMA request */ 161 void *ia_aux; /* driver specific */ 162.Ed 163.El 164.Sh FUNCTIONS 165.Bl -tag -width compact 166.It Fn isa_intr_alloc "ic" "mask" "type" "irq" 167This function is generally not required by device drivers. It is used 168by bridges attaching other busses to the ISA bus. 169.It Fn isa_intr_evcnt "ic" "irq" 170Returns the event counter associated with interrupt line 171.Fa irq . 172.It Fn isa_intr_establish "ic" "irq" "type" "level" "handler" "arg" 173To establish an ISA interrupt handler, a driver calls 174.Fn isa_intr_establish 175with the interrupt number 176.Fa irq , 177type 178.Fa type , 179and level 180.Fa level . 181When the interrupt occurs the function 182.Fa handler 183is called with argument 184.Fa arg . 185Valid values for 186.Fa type 187are: 188.Bl -tag -width compact 189.It IST_NONE 190Reserve interrupt, but don't actually establish. 191.It IST_EDGE 192Edge-triggered interrupt. 193.It IST_LEVEL 194Level-triggered interrupt. 195.It IST_PULSE 196Pulse-triggered interrupt. 197.El 198.sp 199.Fn isa_intr_establish 200returns an opaque handle to an event descriptor if it succeeds, and 201returns NULL on failure. 202.Pp 203.It Fn isa_intr_disestablish "ic" "ih" 204Dis-establish the interrupt handler with handle 205.Fa ih . 206The handle was returned from 207.Fn isa_intr_establish . 208.It Fn isa_dmamap_create "ic" "chan" "size" "flags" 209Creates a DMA map for channel 210.Fa chan . 211It is initialised to accept maximum DMA transfers of size 212.Fa size . 213Valid values for the 214.Fa flags 215argument are the same as for 216.Fn bus_dmamap_create 217(see 218.Xr bus_dma 9 ) . 219This function returns zero on success or an error value on failure. 220.It Fn isa_dmamap_destroy "ic" "chan" 221Destroy the DMA map for DMA channel 222.Fa chan . 223.It Fn isa_dmamem_alloc "ic" "chan" "size" "addrp" "flags" 224Allocate DMA-safe memory of size 225.Fa size 226for channel 227.Fa chan . 228Valid values for the 229.Fa flags 230argument are the same as for 231.Fn bus_dmamem_alloc 232(see 233.Xr bus_dma 9 ) . 234The bus-address of the memory is returned in 235.Fa addrp . 236This function returns zero on success or an error value on failure. 237.It Fn isa_dmamem_free "ic" "chan" "addr" "size" 238Frees memory previously allocated by 239.Fn isa_dmamem_alloc 240for channel 241.Fa chan . 242The bus-address and size of the memory are specified by 243.Fa addr 244and 245.Fa size 246respectively. 247.It Fn isa_dmamem_map "ic" "chan" "addr" "size" "kvap" "flags" 248Maps DMA-safe memory (allocated with 249.Fn isa_dmamem_alloc ) 250specified by bus-address 251.Fa addr 252and of size 253.Fa size 254into kernel virtual address space for DMA channel 255.Fa chan . 256Valid values for the 257.Fa flags 258argument are the same as for 259.Fn bus_dmamem_map 260(see 261.Xr bus_dma 9 ) . 262The kernel virtual address is returned in 263.Fa kvap . 264This function returns zero on success or an error value on failure. 265.It Fn isa_dmamem_unmap "ic" "chan" "kva" "size" 266Unmaps memory (previously mapped with 267.Fn isa_dmamem_map ) 268of size 269.Fa size 270for channel 271.Fa chan . 272The kernel virtual address space used by the mapping is freed. 273.It Fn isa_malloc "ic" "chan" "size" "pool" "flags" 274This function is a shortcut for allocating and mapping DMA-safe memory 275in a single step. The arguments correspond with the arguments to 276.Fn isa_dmamem_alloc 277and 278.Fn isa_dmamem_map . 279The argument 280.Fa pool 281is a pool to record the memory allocation. This function returns 282a pointer to the DMA-safe memory. 283.It Fn isa_free "addrp" "pool" 284This function is a shortcut for unmapping and deallocating DMA-safe 285memory in a single step. It replaces 286.Fn isa_dmamem_unmap 287and 288.Fn isa_dmamem_free . 289The argument 290.Fa addrp 291is the pointer to the DMA-safe memory returned by 292.Fn isa_malloc . 293The argument 294.Fa pool 295is the same as the value passed to 296.Fn isa_malloc . 297.It Fn isa_dmastart "ic" "chan" "addr" "size" "proc" "flags" "bf" 298Load DMA memory specified by address 299.Fa addr 300of size 301.Fa size 302into the DMA controller at channel 303.Fa chan 304and set it in motion. 305The argument 306.Fa proc 307is used to indicate the address space in which the buffer is located. 308If NULL, the buffer is assumed to be in kernel space. Otherwise, the 309buffer is assumed to be in process 310.Fa proc 's 311address space. 312The argument 313.Fa flags 314describes the type of ISA DMA. Valid values are: 315.Bl -tag -width compact 316.It DMAMODE_WRITE 317DMA transfer from host to device. 318.It DMAMODE_READ 319DMA transfer to host from device. 320.It DMAMODE_SINGLE 321Transfer buffer once and stop. 322.It DMAMODE_DEMAND 323Demand mode. 324.It DMAMODE_LOOP 325Transfer buffer continuously in loop until notified to stop. 326.It DMAMODE_LOOPDEMAND 327Transfer buffer continuously in loop and demand mode. 328.El 329.sp 330The argument 331.Fa bf 332is the bus-space flags. Valid values are the same as for 333.Fn bus_dmamap_load 334(see 335.Xr bus_dma 9 ) . 336.It Fn isa_dmaabort "ic" "chan" 337Abort a DMA transfer on channel 338.Fa chan . 339.It Fn isa_dmacount "ic" "chan" 340Returns the offset in the DMA memory of the current DMA transfer on 341channel 342.Fa chan . 343.It Fn isa_dmadone "ic" "chan" 344Unloads the DMA memory 345on channel 346.Fa chan 347after a DMA transfer has completed. 348.It Fn isa_dmamaxsize "ic" "chan" 349Returns the maximum allowable DMA transfer size for channel 350.Fa chan . 351.It Fn isa_drq_isfree "ic" "chan" 352If the 353.Fa ia_drq 354or 355.Fa ia_drq2 356members of 357.Fa struct isa_attach_args 358are wildcarded, then the driver is expected to probe the hardware for 359valid DMA channels. In this case, the driver can check to see if the 360hardware-supported DMA channel 361.Fa chan 362is available for use. 363.It Fn isa_dmacascade "ic" "chan" 364Programs the 8237 DMA controller channel 365.Fa chan 366to accept external DMA control by the device hardware. 367.It Fn isa_mappage "mem" "offset" "prot" 368Provides support for user 369.Xr mmap 2 'ing 370of DMA-safe memory. 371.El 372.Sh AUTOCONFIGURATION 373The ISA bus is an indirect-connection bus. During autoconfiguration 374each driver is required to probe the bus for the presence of a device. 375An ISA driver will receive a pointer to 376.Fa struct isa_attach_args 377hinting at "locations" on the ISA bus where the device may be located. 378They should use the 379.Em ia_iobase , 380.Em ia_iosize , 381.Em ia_maddr , 382and 383.Em ia_msize 384members. Not all of these hints will be necessary; locators may 385be wildcarded with IOBASEUNK and MADDRUNK for 386.Em ia_iobase 387and 388.Em ia_maddr 389respectively. If a driver can probe the device for configuration 390information at default locations, it may update the members of 391.Fa struct isa_attach_args . 392The IRQ and DMA locators can also be wildcarded with IRQUNK and DRQUNK 393respectively. 394.Pp 395During the driver attach step, the I/O and memory address spaces 396should be mapped (see 397.Xr bus_space 9 ) . 398.Sh DMA SUPPORT 399Extensive DMA facilities are provided for the ISA bus. A driver can 400use up to two DMA channels simultaneously. The DMA channels allocated 401during autoconfiguration are passed to the driver during the driver 402attach using the 403.Fa ia_drq 404and 405.Fa ia_drq2 406members of 407.Fa struct isa_attach_args . 408.Pp 409Before allocating resources for DMA transfers on the ISA bus, a driver 410should check the maximum allowable DMA transfer size for the DMA 411channel using 412.Fn isa_dmamaxsize . 413.Pp 414A DMA map should be created first using 415.Fn isa_dmamap_create . 416A DMA map describes how DMA memory is loaded into the DMA controllers. 417Only DMA-safe memory can be used for DMA transfers. DMA-safe memory 418is allocated using 419.Fn isa_dmamem_alloc . 420The memory allocated by 421.Fn isa_dmamem_alloc 422must now be mapped into kernel virtual address space by 423.Fn isa_dmamem_map 424so that it can be accessed by the driver. 425.Pp 426For a DMA transfer from the host to the device, the driver will fill 427the DMA memory with the data to be transferred. The DMA-transfer of 428the memory is started using 429.Fn isa_dmastart 430with 431.Fa flags 432containing DMAMODE_WRITE. 433When the DMA transfer is completed, a call to 434.Fn isa_dmadone 435cleans up the DMA transfer by unloading the memory from the 436controller. 437.Pp 438For a DMA transfer from the device to the host, the DMA-transfer is 439started using 440.Fn isa_dmastart 441with 442.Fa flags 443containing DMAMODE_READ. 444When the DMA transfer is completed, a call to 445.Fn isa_dmadone 446cleans up the DMA transfer by unloading the memory from the 447controller. The memory can now be access by the driver. 448.Pp 449When the DMA resources are no longer required they should be released 450using 451.Fn isa_dmamem_unmap , 452.Fn isa_dmamem_free 453and 454.Fn isa_dmamap_destroy . 455.Sh CODE REFERENCES 456This section describes places within the 457.Nx 458source tree where actual code implementing or utilising the 459machine-independent ISA subsystem can be found. All pathnames are 460relative to 461.Pa /usr/src . 462.Pp 463The ISA subsystem itself is implemented within the files 464.Pa sys/dev/isa/isa.c 465and 466.Pa sys/dev/isa/isadma.c . 467.Sh SEE ALSO 468.Xr isa 4 , 469.Xr autoconf 9 , 470.Xr bus_dma 9 , 471.Xr bus_space 9 , 472.Xr driver 9 , 473.Xr isapnp 9 474.Sh HISTORY 475The machine-independent 476.Nm 477subsystem appeared in 478.Nx 1.2 . 479.Sh BUGS 480The previous behaviour of 481.Fn isa_intr_establish 482was to invoke 483.Fn panic 484on failure. 485.Fn isa_intr_establish 486now returns NULL on failure. Some old drivers written for the former 487behaviour discard the return value. 488