1 /* $NetBSD: isadma.c,v 1.2 2008/12/14 17:03:43 christos Exp $ */ 2 3 /* from: NetBSD:dev/isa/isadma.c */ 4 5 #include <sys/types.h> 6 #include <machine/pio.h> 7 8 #include <lib/libsa/stand.h> 9 10 #include "isadmavar.h" 11 12 #define IO_DMA1 0x000 /* 8237A DMA Controller #1 */ 13 #define IO_DMA2 0x0C0 /* 8237A DMA Controller #2 */ 14 #define DMA37MD_CASCADE 0xc0 /* cascade mode */ 15 #define DMA1_SMSK (IO_DMA1 + 1*10) /* single mask register */ 16 #define DMA1_MODE (IO_DMA1 + 1*11) /* mode register */ 17 #define DMA2_SMSK (IO_DMA2 + 2*10) /* single mask register */ 18 #define DMA2_MODE (IO_DMA2 + 2*11) /* mode register */ 19 20 /* 21 * isa_dmacascade(): program 8237 DMA controller channel to accept 22 * external dma control by a board. 23 */ 24 void isa_dmacascade(int chan)25isa_dmacascade(int chan) 26 { 27 28 #ifdef ISADMA_DEBUG 29 if (chan < 0 || chan > 7) 30 panic("isa_dmacascade: impossible request"); 31 #endif 32 33 /* set dma channel mode, and set dma channel mode */ 34 if ((chan & 4) == 0) { 35 outb(DMA1_MODE, chan | DMA37MD_CASCADE); 36 outb(DMA1_SMSK, chan); 37 } else { 38 chan &= 3; 39 40 outb(DMA2_MODE, chan | DMA37MD_CASCADE); 41 outb(DMA2_SMSK, chan); 42 } 43 } 44