dma.c revision 1.4
1 /* $NetBSD: dma.c,v 1.4 1995/05/14 15:46:17 leo Exp $ */ 2 3 /* 4 * Copyright (c) 1995 Leo Weppelman. 5 * All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 3. All advertising materials mentioning features or use of this software 16 * must display the following acknowledgement: 17 * This product includes software developed by Leo Weppelman. 18 * 4. The name of the author may not be used to endorse or promote products 19 * derived from this software without specific prior written permission 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 22 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 23 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 24 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 25 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 26 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 27 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 28 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 29 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 30 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 31 */ 32 33 /* 34 * This file contains special code dealing with the DMA interface 35 * on the Atari ST. 36 * 37 * The DMA circuitry requires some special treatment for the peripheral 38 * devices which make use of the ST's DMA feature (the hard disk and the 39 * floppy drive). 40 * All devices using DMA need mutually exclusive access and can follow some 41 * standard pattern which will be provided in this file. 42 * 43 * The file contains the following entry points: 44 * 45 * st_dmagrab: ensure exclusive access to the DMA circuitry 46 * st_dmafree: free exclusive access to the DMA circuitry 47 * st_dmawanted: somebody is queued waiting for DMA-access 48 * dmaint: DMA interrupt routine, switches to the current driver 49 * st_dmaaddr_set: specify 24 bit RAM address 50 * st_dmaaddr_get: get address of last DMA-op 51 * st_dmacomm: program DMA, flush FIFO first 52 */ 53 54 #include <sys/param.h> 55 #include <sys/systm.h> 56 #include <sys/kernel.h> 57 #include <sys/queue.h> 58 #include <machine/cpu.h> 59 #include <machine/iomap.h> 60 #include <machine/dma.h> 61 62 #define NDMA_DEV 10 /* Max 2 floppy's, 8 hard-disks */ 63 typedef struct dma_entry { 64 TAILQ_ENTRY(dma_entry) entries; /* List pointers */ 65 void (*call_func)(); /* Call when lock granted */ 66 void (*int_func)(); /* Call on DMA interrupt */ 67 void *softc; /* Arg. to int_func */ 68 int *lock_stat; /* status of DMA lock */ 69 } DMA_ENTRY; 70 71 /* 72 * Preallocated entries. An allocator seem an overkill here. 73 */ 74 static DMA_ENTRY dmatable[NDMA_DEV]; /* preallocated entries */ 75 static int sched_soft = 0; /* callback scheduled */ 76 77 /* 78 * Heads of free and active lists: 79 */ 80 static TAILQ_HEAD(freehead, dma_entry) dma_free; 81 static TAILQ_HEAD(acthead, dma_entry) dma_active; 82 83 static int must_init = 1; /* Must initialize */ 84 85 static void cdmasoft __P((void)); 86 static void init_queues __P((void)); 87 88 static void init_queues() 89 { 90 int i; 91 92 TAILQ_INIT(&dma_free); 93 TAILQ_INIT(&dma_active); 94 95 for(i = 0; i < NDMA_DEV; i++) 96 TAILQ_INSERT_HEAD(&dma_free, &dmatable[i], entries); 97 } 98 99 int st_dmagrab(int_func, call_func, softc, lock_stat, rcaller) 100 void (*int_func)(); 101 void (*call_func)(); 102 void *softc; 103 int *lock_stat; 104 int rcaller; 105 { 106 int sps; 107 DMA_ENTRY *req; 108 109 if(must_init) { 110 init_queues(); 111 must_init = 0; 112 } 113 *lock_stat = DMA_LOCK_REQ; 114 115 sps = splhigh(); 116 117 /* 118 * Create a request... 119 */ 120 if(dma_free.tqh_first == NULL) 121 panic("st_dmagrab: Too many outstanding requests\n"); 122 req = dma_free.tqh_first; 123 TAILQ_REMOVE(&dma_free, dma_free.tqh_first, entries); 124 req->call_func = call_func; 125 req->int_func = int_func; 126 req->softc = softc; 127 req->lock_stat = lock_stat; 128 TAILQ_INSERT_TAIL(&dma_active, req, entries); 129 130 if(dma_active.tqh_first != req) { 131 splx(sps); 132 return(0); 133 } 134 splx(sps); 135 136 /* 137 * We're at the head of the queue, ergo: we got the lock. 138 */ 139 *lock_stat = DMA_LOCK_GRANT; 140 141 if(rcaller) { 142 /* 143 * Just return to caller immediately without going 144 * through 'call_func' first. 145 */ 146 return(1); 147 } 148 149 (*call_func)(softc); /* Call followup function */ 150 return(0); 151 } 152 153 void 154 st_dmafree(softc, lock_stat) 155 void *softc; 156 int *lock_stat; 157 { 158 int sps; 159 DMA_ENTRY *req; 160 161 sps = splhigh(); 162 163 /* 164 * Some validity checks first. 165 */ 166 if((req = dma_active.tqh_first) == NULL) 167 panic("st_dmafree: empty active queue\n"); 168 if(req->softc != softc) 169 printf("Caller of st_dmafree is not lock-owner!\n"); 170 171 /* 172 * Clear lock status, move request from active to free queue. 173 */ 174 *lock_stat = 0; 175 TAILQ_REMOVE(&dma_active, req, entries); 176 TAILQ_INSERT_HEAD(&dma_free, req, entries); 177 178 if((req = dma_active.tqh_first) != NULL) { 179 /* 180 * Call next request through softint handler. This avoids 181 * spl-conflicts. 182 */ 183 *req->lock_stat = DMA_LOCK_GRANT; 184 add_sicallback(req->call_func, req->softc, 0); 185 } 186 splx(sps); 187 return; 188 } 189 190 int 191 st_dmawanted() 192 { 193 return(dma_active.tqh_first->entries.tqe_next != NULL); 194 } 195 196 cdmaint(sr) 197 long sr; /* sr at time of interrupt */ 198 { 199 if(dma_active.tqh_first != NULL) { 200 if(!BASEPRI(sr)) { 201 if(!sched_soft++) 202 add_sicallback(cdmasoft, 0, 0); 203 } 204 else { 205 spl1(); 206 cdmasoft(); 207 } 208 } 209 else printf("DMA interrupt discarded\n"); 210 } 211 212 static void cdmasoft() 213 { 214 int s; 215 void (*int_func)(); 216 void *softc; 217 218 /* 219 * Prevent a race condition here. DMA might be freed while 220 * the callback was pending! 221 */ 222 s = splhigh(); 223 sched_soft = 0; 224 if(dma_active.tqh_first != NULL) { 225 int_func = dma_active.tqh_first->int_func; 226 softc = dma_active.tqh_first->softc; 227 } 228 else int_func = NULL; 229 splx(s); 230 231 if(int_func != NULL) 232 (*int_func)(softc); 233 } 234 235 /* 236 * Setup address for DMA-transfer. 237 * Note: The order _is_ important! 238 */ 239 void 240 st_dmaaddr_set(address) 241 caddr_t address; 242 { 243 register u_long ad = (u_long)address; 244 245 DMA->dma_addr[AD_LOW ] = (ad ) & 0xff; 246 DMA->dma_addr[AD_MID ] = (ad >> 8) & 0xff; 247 DMA->dma_addr[AD_HIGH] = (ad >>16) & 0xff; 248 } 249 250 /* 251 * Get address from DMA unit. 252 */ 253 u_long 254 st_dmaaddr_get() 255 { 256 register u_long ad = 0; 257 258 ad = (DMA->dma_addr[AD_LOW ] & 0xff); 259 ad |= (DMA->dma_addr[AD_MID ] & 0xff) << 8; 260 ad |= (DMA->dma_addr[AD_HIGH] & 0xff) <<16; 261 return(ad); 262 } 263 264 /* 265 * Program the DMA-controller to transfer 'nblk' blocks of 512 bytes. 266 * The DMA_WRBIT trick flushes the FIFO before doing DMA. 267 */ 268 void 269 st_dmacomm(mode, nblk) 270 int mode, nblk; 271 { 272 DMA->dma_mode = mode; 273 DMA->dma_mode = mode ^ DMA_WRBIT; 274 DMA->dma_mode = mode; 275 DMA->dma_data = nblk; 276 DMA->dma_mode = DMA_SCREG | (mode & DMA_WRBIT); 277 } 278
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