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/* $Id: dma.h,v 1.1 2004-01-28 15:24:15 giacomo Exp $

 * linux/include/asm/dma.h: Defines for using and allocating dma channels.

 * Written by Hennus Bergman, 1992.

 * High DMA channel support & info by Hannu Savolainen

 * and John Boyd, Nov. 1992.

 */

#ifndef _ASM_DMA_H

#define _ASM_DMA_H

#include <linux/config.h>

#include <linux/spinlock.h>     /* And spinlocks */

#include <asm/io.h>             /* need byte IO */

#include <linux/delay.h>

#ifdef HAVE_REALLY_SLOW_DMA_CONTROLLER

#define dma_outb        outb_p

#else

#define dma_outb        outb

#endif

#define dma_inb         inb

/*

 * NOTES about DMA transfers:

 *

 *  controller 1: channels 0-3, byte operations, ports 00-1F

 *  controller 2: channels 4-7, word operations, ports C0-DF

 *

 *  - ALL registers are 8 bits only, regardless of transfer size

 *  - channel 4 is not used - cascades 1 into 2.

 *  - channels 0-3 are byte - addresses/counts are for physical bytes

 *  - channels 5-7 are word - addresses/counts are for physical words

 *  - transfers must not cross physical 64K (0-3) or 128K (5-7) boundaries

 *  - transfer count loaded to registers is 1 less than actual count

 *  - controller 2 offsets are all even (2x offsets for controller 1)

 *  - page registers for 5-7 don't use data bit 0, represent 128K pages

 *  - page registers for 0-3 use bit 0, represent 64K pages

 *

 * DMA transfers are limited to the lower 16MB of _physical_ memory.  

 * Note that addresses loaded into registers must be _physical_ addresses,

 * not logical addresses (which may differ if paging is active).

 *

 *  Address mapping for channels 0-3:

 *

 *   A23 ... A16 A15 ... A8  A7 ... A0    (Physical addresses)

 *    |  ...  |   |  ... |   |  ... |

 *    |  ...  |   |  ... |   |  ... |

 *    |  ...  |   |  ... |   |  ... |

 *   P7  ...  P0  A7 ... A0  A7 ... A0  

 * |    Page    | Addr MSB | Addr LSB |   (DMA registers)

 *

 *  Address mapping for channels 5-7:

 *

 *   A23 ... A17 A16 A15 ... A9 A8 A7 ... A1 A0    (Physical addresses)

 *    |  ...  |   \   \   ... \  \  \  ... \  \

 *    |  ...  |    \   \   ... \  \  \  ... \  (not used)

 *    |  ...  |     \   \   ... \  \  \  ... \

 *   P7  ...  P1 (0) A7 A6  ... A0 A7 A6 ... A0  

 * |      Page      |  Addr MSB   |  Addr LSB  |   (DMA registers)

 *

 * Again, channels 5-7 transfer _physical_ words (16 bits), so addresses

 * and counts _must_ be word-aligned (the lowest address bit is _ignored_ at

 * the hardware level, so odd-byte transfers aren't possible).

 *

 * Transfer count (_not # bytes_) is limited to 64K, represented as actual

 * count - 1 : 64K => 0xFFFF, 1 => 0x0000.  Thus, count is always 1 or more,

 * and up to 128K bytes may be transferred on channels 5-7 in one operation.

 *

 */

#define MAX_DMA_CHANNELS        8

/* The maximum address that we can perform a DMA transfer to on this platform */

#define MAX_DMA_ADDRESS      (PAGE_OFFSET+0x1000000)

/* 8237 DMA controllers */

#define IO_DMA1_BASE    0x00    /* 8 bit slave DMA, channels 0..3 */

#define IO_DMA2_BASE    0xC0    /* 16 bit master DMA, ch 4(=slave input)..7 */

/* DMA controller registers */

#define DMA1_CMD_REG            0x08    /* command register (w) */

#define DMA1_STAT_REG           0x08    /* status register (r) */

#define DMA1_REQ_REG            0x09    /* request register (w) */

#define DMA1_MASK_REG           0x0A    /* single-channel mask (w) */

#define DMA1_MODE_REG           0x0B    /* mode register (w) */

#define DMA1_CLEAR_FF_REG       0x0C    /* clear pointer flip-flop (w) */

#define DMA1_TEMP_REG           0x0D    /* Temporary Register (r) */

#define DMA1_RESET_REG          0x0D    /* Master Clear (w) */

#define DMA1_CLR_MASK_REG       0x0E    /* Clear Mask */

#define DMA1_MASK_ALL_REG       0x0F    /* all-channels mask (w) */

#define DMA2_CMD_REG            0xD0    /* command register (w) */

#define DMA2_STAT_REG           0xD0    /* status register (r) */

#define DMA2_REQ_REG            0xD2    /* request register (w) */

#define DMA2_MASK_REG           0xD4    /* single-channel mask (w) */

#define DMA2_MODE_REG           0xD6    /* mode register (w) */

#define DMA2_CLEAR_FF_REG       0xD8    /* clear pointer flip-flop (w) */

#define DMA2_TEMP_REG           0xDA    /* Temporary Register (r) */

#define DMA2_RESET_REG          0xDA    /* Master Clear (w) */

#define DMA2_CLR_MASK_REG       0xDC    /* Clear Mask */

#define DMA2_MASK_ALL_REG       0xDE    /* all-channels mask (w) */

#define DMA_ADDR_0              0x00    /* DMA address registers */

#define DMA_ADDR_1              0x02

#define DMA_ADDR_2              0x04

#define DMA_ADDR_3              0x06

#define DMA_ADDR_4              0xC0

#define DMA_ADDR_5              0xC4

#define DMA_ADDR_6              0xC8

#define DMA_ADDR_7              0xCC

#define DMA_CNT_0               0x01    /* DMA count registers */

#define DMA_CNT_1               0x03

#define DMA_CNT_2               0x05

#define DMA_CNT_3               0x07

#define DMA_CNT_4               0xC2

#define DMA_CNT_5               0xC6

#define DMA_CNT_6               0xCA

#define DMA_CNT_7               0xCE

#define DMA_PAGE_0              0x87    /* DMA page registers */

#define DMA_PAGE_1              0x83

#define DMA_PAGE_2              0x81

#define DMA_PAGE_3              0x82

#define DMA_PAGE_5              0x8B

#define DMA_PAGE_6              0x89

#define DMA_PAGE_7              0x8A

#define DMA_MODE_READ   0x44    /* I/O to memory, no autoinit, increment, single mode */

#define DMA_MODE_WRITE  0x48    /* memory to I/O, no autoinit, increment, single mode */

#define DMA_MODE_CASCADE 0xC0   /* pass thru DREQ->HRQ, DACK<-HLDA only */

#define DMA_AUTOINIT    0x10

extern spinlock_t  dma_spin_lock;

static __inline__ unsigned long claim_dma_lock(void)

{

        unsigned long flags;

        spin_lock_irqsave(&dma_spin_lock, flags);

        return flags;

}

static __inline__ void release_dma_lock(unsigned long flags)

{

        spin_unlock_irqrestore(&dma_spin_lock, flags);

}

/* enable/disable a specific DMA channel */

static __inline__ void enable_dma(unsigned int dmanr)

{

        if (dmanr<=3)

                dma_outb(dmanr,  DMA1_MASK_REG);

        else

                dma_outb(dmanr & 3,  DMA2_MASK_REG);

}

static __inline__ void disable_dma(unsigned int dmanr)

{

        if (dmanr<=3)

                dma_outb(dmanr | 4,  DMA1_MASK_REG);

        else

                dma_outb((dmanr & 3) | 4,  DMA2_MASK_REG);

}

/* Clear the 'DMA Pointer Flip Flop'.

 * Write 0 for LSB/MSB, 1 for MSB/LSB access.

 * Use this once to initialize the FF to a known state.

 * After that, keep track of it. :-)

 * --- In order to do that, the DMA routines below should ---

 * --- only be used while holding the DMA lock ! ---

 */

static __inline__ void clear_dma_ff(unsigned int dmanr)

{

        if (dmanr<=3)

                dma_outb(0,  DMA1_CLEAR_FF_REG);

        else

                dma_outb(0,  DMA2_CLEAR_FF_REG);

}

/* set mode (above) for a specific DMA channel */

static __inline__ void set_dma_mode(unsigned int dmanr, char mode)

{

        if (dmanr<=3)

                dma_outb(mode | dmanr,  DMA1_MODE_REG);

        else

                dma_outb(mode | (dmanr&3),  DMA2_MODE_REG);

}

/* Set only the page register bits of the transfer address.

 * This is used for successive transfers when we know the contents of

 * the lower 16 bits of the DMA current address register, but a 64k boundary

 * may have been crossed.

 */

static __inline__ void set_dma_page(unsigned int dmanr, char pagenr)

{

        switch(dmanr) {

                case 0:

                        dma_outb(pagenr, DMA_PAGE_0);

                        break;

                case 1:

                        dma_outb(pagenr, DMA_PAGE_1);

                        break;

                case 2:

                        dma_outb(pagenr, DMA_PAGE_2);

                        break;

                case 3:

                        dma_outb(pagenr, DMA_PAGE_3);

                        break;

                case 5:

                        dma_outb(pagenr & 0xfe, DMA_PAGE_5);

                        break;

                case 6:

                        dma_outb(pagenr & 0xfe, DMA_PAGE_6);

                        break;

                case 7:

                        dma_outb(pagenr & 0xfe, DMA_PAGE_7);

                        break;

        }

}

/* Set transfer address & page bits for specific DMA channel.

 * Assumes dma flipflop is clear.

 */

static __inline__ void set_dma_addr(unsigned int dmanr, unsigned int a)

{

        set_dma_page(dmanr, a>>16);

        if (dmanr <= 3)  {

            dma_outb( a & 0xff, ((dmanr&3)<<1) + IO_DMA1_BASE );

            dma_outb( (a>>8) & 0xff, ((dmanr&3)<<1) + IO_DMA1_BASE );

        }  else  {

            dma_outb( (a>>1) & 0xff, ((dmanr&3)<<2) + IO_DMA2_BASE );

            dma_outb( (a>>9) & 0xff, ((dmanr&3)<<2) + IO_DMA2_BASE );

        }

}

/* Set transfer size (max 64k for DMA0..3, 128k for DMA5..7) for

 * a specific DMA channel.

 * You must ensure the parameters are valid.

 * NOTE: from a manual: "the number of transfers is one more

 * than the initial word count"! This is taken into account.

 * Assumes dma flip-flop is clear.

 * NOTE 2: "count" represents _bytes_ and must be even for channels 5-7.

 */

static __inline__ void set_dma_count(unsigned int dmanr, unsigned int count)

{

        count--;

        if (dmanr <= 3)  {

            dma_outb( count & 0xff, ((dmanr&3)<<1) + 1 + IO_DMA1_BASE );

            dma_outb( (count>>8) & 0xff, ((dmanr&3)<<1) + 1 + IO_DMA1_BASE );

        } else {

            dma_outb( (count>>1) & 0xff, ((dmanr&3)<<2) + 2 + IO_DMA2_BASE );

            dma_outb( (count>>9) & 0xff, ((dmanr&3)<<2) + 2 + IO_DMA2_BASE );

        }

}

/* Get DMA residue count. After a DMA transfer, this

 * should return zero. Reading this while a DMA transfer is

 * still in progress will return unpredictable results.

 * If called before the channel has been used, it may return 1.

 * Otherwise, it returns the number of _bytes_ left to transfer.

 *

 * Assumes DMA flip-flop is clear.

 */

static __inline__ int get_dma_residue(unsigned int dmanr)

{

        unsigned int io_port = (dmanr<=3)? ((dmanr&3)<<1) + 1 + IO_DMA1_BASE

                                         : ((dmanr&3)<<2) + 2 + IO_DMA2_BASE;

        /* using short to get 16-bit wrap around */

        unsigned short count;

        count = 1 + dma_inb(io_port);

        count += dma_inb(io_port) << 8;

        return (dmanr<=3)? count : (count<<1);

}

/* These are in kernel/dma.c: */

extern int request_dma(unsigned int dmanr, const char * device_id);     /* reserve a DMA channel */

extern void free_dma(unsigned int dmanr);       /* release it again */

/* From PCI */

#ifdef CONFIG_PCI

extern int isa_dma_bridge_buggy;

#else

#define isa_dma_bridge_buggy    (0)

#endif

#endif /* _ASM_DMA_H */