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// Code to support legacy Intel 8237 DMA chip.
//
// Copyright (C) 2008,2009 Kevin O'Connor <kevin@koconnor.net>
// Copyright (C) 2002 MandrakeSoft S.A.
//
// This file may be distributed under the terms of the GNU LGPLv3 license.
#include "util.h" // dma_setup
#include "x86.h" // outb
#define PORT_DMA_ADDR_2 0x0004
#define PORT_DMA_CNT_2 0x0005
#define PORT_DMA1_MASK_REG 0x000a
#define PORT_DMA1_MODE_REG 0x000b
#define PORT_DMA1_CLEAR_FF_REG 0x000c
#define PORT_DMA1_MASTER_CLEAR 0x000d
#define PORT_DMA_PAGE_2 0x0081
#define PORT_DMA2_MASK_REG 0x00d4
#define PORT_DMA2_MODE_REG 0x00d6
#define PORT_DMA2_MASTER_CLEAR 0x00da
// Setup the DMA controller for a floppy transfer.
int
dma_floppy(u32 addr, int count, int isWrite)
{
// check for 64K boundary overrun
u16 end = count - 1;
u32 last_addr = addr + end;
if ((addr >> 16) != (last_addr >> 16))
return -1;
u8 mode_register = 0x46; // single mode, increment, autoinit disable,
if (isWrite)
mode_register = 0x4a;
outb(0x06, PORT_DMA1_MASK_REG);
outb(0x00, PORT_DMA1_CLEAR_FF_REG); // clear flip-flop
outb(addr, PORT_DMA_ADDR_2);
outb(addr>>8, PORT_DMA_ADDR_2);
outb(0x00, PORT_DMA1_CLEAR_FF_REG); // clear flip-flop
outb(end, PORT_DMA_CNT_2);
outb(end>>8, PORT_DMA_CNT_2);
// port 0b: DMA-1 Mode Register
// transfer type=write, channel 2
outb(mode_register, PORT_DMA1_MODE_REG);
// port 81: DMA-1 Page Register, channel 2
outb(addr>>16, PORT_DMA_PAGE_2);
outb(0x02, PORT_DMA1_MASK_REG); // unmask channel 2
return 0;
}
// Reset DMA controller
void
dma_setup(void)
{
// first reset the DMA controllers
outb(0, PORT_DMA1_MASTER_CLEAR);
outb(0, PORT_DMA2_MASTER_CLEAR);
// then initialize the DMA controllers
outb(0xc0, PORT_DMA2_MODE_REG);
outb(0x00, PORT_DMA2_MASK_REG);
}
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