Contributors: 6
Author Tokens Token Proportion Commits Commit Proportion
Linus Torvalds (pre-git) 949 94.99% 6 37.50%
Ralf Baechle 28 2.80% 6 37.50%
Thomas Bogendoerfer 12 1.20% 1 6.25%
David Daney 5 0.50% 1 6.25%
Franck Bui-Huu 4 0.40% 1 6.25%
Greg Kroah-Hartman 1 0.10% 1 6.25%
Total 999 16 


/* SPDX-License-Identifier: GPL-2.0 */
/*
 * 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.
 *
 * NOTE: all this is true *only* for ISA/EISA expansions on Mips boards
 * and can only be used for expansion cards. Onboard DMA controllers, such
 * as the R4030 on Jazz boards behave totally different!
 */

#ifndef _ASM_DMA_H
#define _ASM_DMA_H

#include <asm/io.h>			/* need byte IO */
#include <linux/spinlock.h>		/* And spinlocks */
#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.
 *
 */

#ifndef CONFIG_GENERIC_ISA_DMA_SUPPORT_BROKEN
#define MAX_DMA_CHANNELS	8
#endif

/*
 * The maximum address in KSEG0 that we can perform a DMA transfer to on this
 * platform.  This describes only the PC style part of the DMA logic like on
 * Deskstations or Acer PICA but not the much more versatile DMA logic used
 * for the local devices on Acer PICA or Magnums.
 */
#if defined(CONFIG_SGI_IP22) || defined(CONFIG_SGI_IP28)
/* don't care; ISA bus master won't work, ISA slave DMA supports 32bit addr */
#define MAX_DMA_ADDRESS		PAGE_OFFSET
#else
#define MAX_DMA_ADDRESS		(PAGE_OFFSET + 0x01000000)
#endif
#define MAX_DMA_PFN		PFN_DOWN(virt_to_phys((void *)MAX_DMA_ADDRESS))

#ifndef MAX_DMA32_PFN
#define MAX_DMA32_PFN		(1UL << (32 - PAGE_SHIFT))
#endif

/* 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 */