/*
 * include/asm-alpha/dma.h
 *
 * This is essentially the same as the i386 DMA stuff, as the AlphaPCs
 * use ISA-compatible dma.  The only extension is support for high-page
 * registers that allow to set the top 8 bits of a 32-bit DMA address.
 * This register should be written last when setting up a DMA address
 * as this will also enable DMA across 64 KB boundaries.
 */

/* $Id: dma.h,v 1.7 1992/12/14 00:29:34 root Exp root $
 * 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/spinlock.h>
#include <asm/io.h>

#define dma_outb	outb
#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

/*
  ISA DMA limitations on Alpha platforms,

  These may be due to SIO (PCI<->ISA bridge) chipset limitation, or
  just a wiring limit.
*/

/* The maximum address for ISA DMA transfer on Alpha XL, due to an
   hardware SIO limitation, is 64MB.
*/
#define ALPHA_XL_MAX_ISA_DMA_ADDRESS		0x04000000UL

/* The maximum address for ISA DMA transfer on RUFFIAN,
   due to an hardware SIO limitation, is 16MB.
*/
#define ALPHA_RUFFIAN_MAX_ISA_DMA_ADDRESS	0x01000000UL

/* The maximum address for ISA DMA transfer on SABLE, and some ALCORs,
   due to an hardware SIO chip limitation, is 2GB.
*/
#define ALPHA_SABLE_MAX_ISA_DMA_ADDRESS		0x80000000UL
#define ALPHA_ALCOR_MAX_ISA_DMA_ADDRESS		0x80000000UL

/*
  Maximum address for all the others is the complete 32-bit bus
  address space.
*/
#define ALPHA_MAX_ISA_DMA_ADDRESS		0x100000000UL

#ifdef CONFIG_ALPHA_GENERIC
# define MAX_ISA_DMA_ADDRESS		(alpha_mv.max_isa_dma_address)
#else
# if defined(CONFIG_ALPHA_XL)
#  define MAX_ISA_DMA_ADDRESS		ALPHA_XL_MAX_ISA_DMA_ADDRESS
# elif defined(CONFIG_ALPHA_RUFFIAN)
#  define MAX_ISA_DMA_ADDRESS		ALPHA_RUFFIAN_MAX_ISA_DMA_ADDRESS
# elif defined(CONFIG_ALPHA_SABLE)
#  define MAX_ISA_DMA_ADDRESS		ALPHA_SABLE_MAX_ISA_DMA_ADDRESS
# elif defined(CONFIG_ALPHA_ALCOR)
#  define MAX_ISA_DMA_ADDRESS		ALPHA_ALCOR_MAX_ISA_DMA_ADDRESS