dma.c revision 1.2
1 /* $NetBSD: dma.c,v 1.2 1995/04/22 22:18:17 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: specify 24 bit RAM address 50 * st_dmacomm: program DMA, flush FIFO first 51 */ 52 53 #include <sys/param.h> 54 #include <sys/systm.h> 55 #include <sys/kernel.h> 56 #include <machine/cpu.h> 57 #include <machine/iomap.h> 58 #include <machine/dma.h> 59 60 #define NDMA_DEV 10 /* Max 2 floppy's, 8 hard-disks */ 61 typedef struct { 62 void (*call_func)(); 63 void (*int_func)(); 64 void *softc; 65 } DMA_DISP; 66 67 static DMA_DISP dispatch[NDMA_DEV]; /* dispatch table */ 68 static int dma_free = 0; /* next free entry in dispatch table */ 69 static int dma_curr = 0; /* current entry in dispatch table */ 70 static int dmalock = 0; /* if != 0, dma is not free */ 71 static void (*xxxint)(); /* current interrupt function */ 72 static void *dma_softc; /* Device currently owning DMA-intr */ 73 static int sched_soft = 0; /* Software interrupt scheduled */ 74 75 static void cdmasoft __P((void)); 76 77 int st_dmagrab(int_func, call_func, softc, rcaller) 78 void (*int_func)(); 79 void (*call_func)(); 80 void *softc; 81 int rcaller; 82 { 83 int sps; 84 DMA_DISP *disp; 85 86 sps = splbio(); 87 88 if(dmalock) { 89 disp = &dispatch[dma_free++]; 90 if(dma_free >= NDMA_DEV) 91 dma_free = 0; 92 if(disp->call_func != NULL) 93 panic("dma dispatch table overflow"); 94 disp->call_func = call_func; 95 disp->int_func = int_func; 96 disp->softc = softc; 97 splx(sps); 98 return(0); 99 } 100 dmalock++; 101 xxxint = int_func; /* Grab DMA interrupts */ 102 dma_softc = softc; /* Identify device which got DMA */ 103 if(rcaller) { 104 /* 105 * Just return to caller immediately without going 106 * through 'call_func' first. 107 */ 108 return(1); 109 } 110 111 (*call_func)(softc); /* Call followup function */ 112 splx(sps); 113 return(0); 114 } 115 116 void 117 st_dmafree() 118 { 119 int sps; 120 DMA_DISP *disp; 121 122 sps = splbio(); 123 disp = &dispatch[dma_curr]; 124 if(disp->call_func != NULL) { 125 xxxint = disp->int_func; 126 dma_softc = disp->softc; 127 (*disp->call_func)(dma_softc); 128 disp->call_func = NULL; 129 if(++dma_curr >= NDMA_DEV) 130 dma_curr = 0; 131 splx(sps); 132 return; 133 } 134 dmalock = 0; 135 xxxint = NULL; /* no more DMA interrupts */ 136 splx(sps); 137 } 138 139 int 140 st_dmawanted() 141 { 142 return(dispatch[dma_curr].call_func != NULL); 143 } 144 145 cdmaint(sr) 146 long sr; /* sr at time of interrupt */ 147 { 148 if(xxxint != NULL) { 149 if(!BASEPRI(sr)) { 150 if(!sched_soft++) 151 add_sicallback(cdmasoft, 0, 0); 152 } 153 else { 154 spl1(); 155 cdmasoft(); 156 } 157 } 158 else printf("DMA interrupt discarded\r\n"); 159 } 160 161 static void cdmasoft() 162 { 163 sched_soft = 0; 164 (*xxxint)(dma_softc); 165 } 166 167 /* 168 * Setup address for DMA-transfer. 169 * Note: The order _is_ important! 170 */ 171 void 172 st_dmaaddr(address) 173 caddr_t address; 174 { 175 register u_long ad = (u_long)address; 176 177 DMA->dma_addr[AD_LOW ] = (ad ) & 0xff; 178 DMA->dma_addr[AD_MID ] = (ad >> 8) & 0xff; 179 DMA->dma_addr[AD_HIGH] = (ad >>16) & 0xff; 180 } 181 182 /* 183 * Program the DMA-controller to transfer 'nblk' blocks of 512 bytes. 184 * The DMA_WRBIT trick flushes the FIFO before doing DMA. 185 */ 186 void 187 st_dmacomm(mode, data) 188 int mode, data; 189 { 190 DMA->dma_mode = mode; 191 DMA->dma_mode = mode ^ DMA_WRBIT; 192 DMA->dma_mode = mode; 193 DMA->dma_data = data; 194 } 195
Indexes created Tue Sep 30 20:09:53 GMT 2025