/* $NetBSD: dma.c,v 1.3 1995/04/30 12:04:48 leo Exp $ */ /* * Copyright (c) 1995 Leo Weppelman. * All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. All advertising materials mentioning features or use of this software * must display the following acknowledgement: * This product includes software developed by Leo Weppelman. * 4. The name of the author may not be used to endorse or promote products * derived from this software without specific prior written permission * * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */ /* * This file contains special code dealing with the DMA interface * on the Atari ST. * * The DMA circuitry requires some special treatment for the peripheral * devices which make use of the ST's DMA feature (the hard disk and the * floppy drive). * All devices using DMA need mutually exclusive access and can follow some * standard pattern which will be provided in this file. * * The file contains the following entry points: * * st_dmagrab: ensure exclusive access to the DMA circuitry * st_dmafree: free exclusive access to the DMA circuitry * st_dmawanted: somebody is queued waiting for DMA-access * dmaint: DMA interrupt routine, switches to the current driver * st_dmaaddr: specify 24 bit RAM address * st_dmacomm: program DMA, flush FIFO first */ #include #include #include #include #include #include #include #define NDMA_DEV 10 /* Max 2 floppy's, 8 hard-disks */ typedef struct dma_entry { TAILQ_ENTRY(dma_entry) entries; /* List pointers */ void (*call_func)(); /* Call when lock granted */ void (*int_func)(); /* Call on DMA interrupt */ void *softc; /* Arg. to int_func */ int *lock_stat; /* status of DMA lock */ } DMA_ENTRY; /* * Preallocated entries. An allocator seem an overkill here. */ static DMA_ENTRY dmatable[NDMA_DEV]; /* preallocated entries */ static int sched_soft = 0; /* callback scheduled */ /* * Heads of free and active lists: */ static TAILQ_HEAD(freehead, dma_entry) dma_free; static TAILQ_HEAD(acthead, dma_entry) dma_active; static int must_init = 1; /* Must initialize */ static void cdmasoft __P((void)); static void init_queues __P((void)); static void init_queues() { int i; TAILQ_INIT(&dma_free); TAILQ_INIT(&dma_active); for(i = 0; i < NDMA_DEV; i++) TAILQ_INSERT_HEAD(&dma_free, &dmatable[i], entries); } int st_dmagrab(int_func, call_func, softc, lock_stat, rcaller) void (*int_func)(); void (*call_func)(); void *softc; int *lock_stat; int rcaller; { int sps; DMA_ENTRY *req; if(must_init) { init_queues(); must_init = 0; } *lock_stat = DMA_LOCK_REQ; sps = splhigh(); /* * Create a request... */ if(dma_free.tqh_first == NULL) panic("st_dmagrab: Too many outstanding requests\n"); req = dma_free.tqh_first; TAILQ_REMOVE(&dma_free, dma_free.tqh_first, entries); req->call_func = call_func; req->int_func = int_func; req->softc = softc; req->lock_stat = lock_stat; TAILQ_INSERT_TAIL(&dma_active, req, entries); if(dma_active.tqh_first != req) { splx(sps); return(0); } splx(sps); /* * We're at the head of the queue, ergo: we got the lock. */ *lock_stat = DMA_LOCK_GRANT; if(rcaller) { /* * Just return to caller immediately without going * through 'call_func' first. */ return(1); } (*call_func)(softc); /* Call followup function */ return(0); } void st_dmafree(softc, lock_stat) void *softc; int *lock_stat; { int sps; DMA_ENTRY *req; sps = splhigh(); /* * Some validity checks first. */ if((req = dma_active.tqh_first) == NULL) panic("st_dmafree: empty active queue\n"); if(req->softc != softc) printf("Caller of st_dmafree is not lock-owner!\n"); /* * Clear lock status, move request from active to free queue. */ *lock_stat = 0; TAILQ_REMOVE(&dma_active, req, entries); TAILQ_INSERT_HEAD(&dma_free, req, entries); if((req = dma_active.tqh_first) != NULL) { /* * Call next request through softint handler. This avoids * spl-conflicts. */ *req->lock_stat = DMA_LOCK_GRANT; add_sicallback(req->call_func, req->softc, 0); } splx(sps); return; } int st_dmawanted() { return(dma_active.tqh_first->entries.tqe_next != NULL); } cdmaint(sr) long sr; /* sr at time of interrupt */ { if(dma_active.tqh_first != NULL) { if(!BASEPRI(sr)) { if(!sched_soft++) add_sicallback(cdmasoft, 0, 0); } else { spl1(); cdmasoft(); } } else printf("DMA interrupt discarded\n"); } static void cdmasoft() { sched_soft = 0; (*dma_active.tqh_first->int_func)(dma_active.tqh_first->softc); } /* * Setup address for DMA-transfer. * Note: The order _is_ important! */ void st_dmaaddr(address) caddr_t address; { register u_long ad = (u_long)address; DMA->dma_addr[AD_LOW ] = (ad ) & 0xff; DMA->dma_addr[AD_MID ] = (ad >> 8) & 0xff; DMA->dma_addr[AD_HIGH] = (ad >>16) & 0xff; } /* * Program the DMA-controller to transfer 'nblk' blocks of 512 bytes. * The DMA_WRBIT trick flushes the FIFO before doing DMA. */ void st_dmacomm(mode, data) int mode, data; { DMA->dma_mode = mode; DMA->dma_mode = mode ^ DMA_WRBIT; DMA->dma_mode = mode; DMA->dma_data = data; }