scsi_dma.c

linux和2410结合开发 用他可以生成2410所需的zImage文件

/*
 *  scsi_dma.c Copyright (C) 2000 Eric Youngdale
 *
 *  mid-level SCSI DMA bounce buffer allocator
 *
 */

#define __NO_VERSION__
#include <linux/config.h>
#include <linux/module.h>
#include <linux/blk.h>


#include "scsi.h"
#include "hosts.h"
#include "constants.h"

#ifdef CONFIG_KMOD
#include <linux/kmod.h>
#endif

/*
 * PAGE_SIZE must be a multiple of the sector size (512).  True
 * for all reasonably recent architectures (even the VAX...).
 */
#define SECTOR_SIZE		512
#define SECTORS_PER_PAGE	(PAGE_SIZE/SECTOR_SIZE)

#if SECTORS_PER_PAGE <= 8
typedef unsigned char FreeSectorBitmap;
#elif SECTORS_PER_PAGE <= 32
typedef unsigned int FreeSectorBitmap;
#elif SECTORS_PER_PAGE <= 64
#if 0
typedef unsigned long long FreeSectorBitmap;
#else
typedef struct {
	unsigned long l,h;
} FreeSectorBitmap;
#define LARGE_MALLOC
#endif
#else
#error You lose.
#endif

/*
 * Used for access to internal allocator used for DMA safe buffers.
 */
static spinlock_t allocator_request_lock = SPIN_LOCK_UNLOCKED;

static FreeSectorBitmap *dma_malloc_freelist = NULL;
static int need_isa_bounce_buffers;
static unsigned int dma_sectors = 0;
unsigned int scsi_dma_free_sectors = 0;
unsigned int scsi_need_isa_buffer = 0;
static unsigned char **dma_malloc_pages = NULL;

/*
 * Function:    scsi_malloc
 *
 * Purpose:     Allocate memory from the DMA-safe pool.
 *
 * Arguments:   len       - amount of memory we need.
 *
 * Lock status: No locks assumed to be held.  This function is SMP-safe.
 *
 * Returns:     Pointer to memory block.
 *
 * Notes:       Prior to the new queue code, this function was not SMP-safe.
 *              This function can only allocate in units of sectors
 *              (i.e. 512 bytes).
 *
 *              We cannot use the normal system allocator becuase we need
 *              to be able to guarantee that we can process a complete disk
 *              I/O request without touching the system allocator.  Think
 *              about it - if the system were heavily swapping, and tried to
 *              write out a block of memory to disk, and the SCSI code needed
 *              to allocate more memory in order to be able to write the
 *              data to disk, you would wedge the system.
 */
#ifndef LARGE_MALLOC
void *scsi_malloc(unsigned int len)
{
	unsigned int nbits, mask;
	unsigned long flags;

	int i, j;
	if (len % SECTOR_SIZE != 0 || len > PAGE_SIZE)
		return NULL;

	nbits = len >> 9;
	mask = (1 << nbits) - 1;

	spin_lock_irqsave(&allocator_request_lock, flags);

	for (i = 0; i < dma_sectors / SECTORS_PER_PAGE; i++)
		for (j = 0; j <= SECTORS_PER_PAGE - nbits; j++) {
			if ((dma_malloc_freelist[i] & (mask << j)) == 0) {
				dma_malloc_freelist[i] |= (mask << j);
				scsi_dma_free_sectors -= nbits;
#ifdef DEBUG
				SCSI_LOG_MLQUEUE(3, printk("SMalloc: %d %p [From:%p]\n", len, dma_malloc_pages[i] + (j << 9)));
				printk("SMalloc: %d %p [From:%p]\n", len, dma_malloc_pages[i] + (j << 9));
#endif
				spin_unlock_irqrestore(&allocator_request_lock, flags);
				return (void *) ((unsigned long) dma_malloc_pages[i] + (j << 9));
			}
		}
	spin_unlock_irqrestore(&allocator_request_lock, flags);
	return NULL;		/* Nope.  No more */
}

/*
 * Function:    scsi_free
 *
 * Purpose:     Free memory into the DMA-safe pool.
 *
 * Arguments:   ptr       - data block we are freeing.
 *              len       - size of block we are freeing.
 *
 * Lock status: No locks assumed to be held.  This function is SMP-safe.
 *
 * Returns:     Nothing
 *
 * Notes:       This function *must* only be used to free memory
 *              allocated from scsi_malloc().
 *
 *              Prior to the new queue code, this function was not SMP-safe.
 *              This function can only allocate in units of sectors
 *              (i.e. 512 bytes).
 */
int scsi_free(void *obj, unsigned int len)
{
	unsigned int page, sector, nbits, mask;
	unsigned long flags;

#ifdef DEBUG
	unsigned long ret = 0;

#ifdef __mips__
	__asm__ __volatile__("move\t%0,$31":"=r"(ret));
#else
	ret = __builtin_return_address(0);
#endif
	printk("scsi_free %p %d\n", obj, len);
	SCSI_LOG_MLQUEUE(3, printk("SFree: %p %d\n", obj, len));
#endif

	spin_lock_irqsave(&allocator_request_lock, flags);

	for (page = 0; page < dma_sectors / SECTORS_PER_PAGE; page++) {
		unsigned long page_addr = (unsigned long) dma_malloc_pages[page];
		if ((unsigned long) obj >= page_addr &&
		    (unsigned long) obj < page_addr + PAGE_SIZE) {
			sector = (((unsigned long) obj) - page_addr) >> 9;

			nbits = len >> 9;
			mask = (1 << nbits) - 1;

			if (sector + nbits > SECTORS_PER_PAGE)
				panic("scsi_free:Bad memory alignment");

			if ((dma_malloc_freelist[page] &
			     (mask << sector)) != (mask << sector)) {
#ifdef DEBUG
				printk("scsi_free(obj=%p, len=%d) called from %08lx\n",
				       obj, len, ret);
#endif
				panic("scsi_free:Trying to free unused memory");
			}
			scsi_dma_free_sectors += nbits;
			dma_malloc_freelist[page] &= ~(mask << sector);
			spin_unlock_irqrestore(&allocator_request_lock, flags);
			return 0;
		}
	}
	panic("scsi_free:Bad offset");
}

#else

void *scsi_malloc(unsigned int len)
{
	unsigned int nbits;
	unsigned long maskl, maskh, flags;
	FreeSectorBitmap *fsb;
	int i;

	if (len % SECTOR_SIZE != 0 || len > PAGE_SIZE)
		return NULL;

	save_flags_cli (flags);
	nbits = len >> 9;
	if (nbits < 32) {
		maskl = (1 << nbits) - 1;
		maskh = 0;
	} else {
		maskl = (unsigned long)-1;
		maskh = (1 << (nbits - 32)) - 1;
	}

	fsb = dma_malloc_freelist;

	for (i = 0; i < dma_sectors / SECTORS_PER_PAGE; i++) {
		unsigned long mml, mmh;
		int j;
		mml = maskl;
		mmh = maskh;
		j = 0;
		do {
			if ((fsb->l & mml) == 0 && (fsb->h & mmh) == 0) {
				fsb->h |= mmh;
				fsb->l |= mml;
				restore_flags (flags);
				scsi_dma_free_sectors -= nbits;
#ifdef DEBUG
				printk("SMalloc: %d %p\n",len, dma_malloc_pages[i] + (j << 9));
#endif
				return (void *) ((unsigned long) dma_malloc_pages[i] + (j << 9));
			}
			mmh = (mmh << 1) | (mml >> 31);
			mml <<= 1;
			j++;
		} while (!(mmh & (1 << 31)));
		fsb ++;
	}
	return NULL;  /* Nope.  No more */
}

int scsi_free(void *obj, unsigned int len)
{
	unsigned int page, sector, nbits;
	unsigned long maskl, maskh, flags;

#ifdef DEBUG
	printk("scsi_free %p %d\n",obj, len);
#endif

	for (page = 0; page < dma_sectors / SECTORS_PER_PAGE; page++) {
		unsigned long page_addr = (unsigned long) dma_malloc_pages[page];
		if ((unsigned long) obj >= page_addr &&
		    (unsigned long) obj < page_addr + PAGE_SIZE) {
			sector = (((unsigned long) obj) - page_addr) >> 9;
			nbits = len >> 9;
			if (nbits < 32) {
				maskl = (1 << nbits) - 1;
				maskh = 0;
			} else {
				maskl = (unsigned long)-1;
				maskh = (1 << (nbits - 32)) - 1;
			}
			if ((sector + nbits) > SECTORS_PER_PAGE)
				panic ("scsi_free:Bad memory alignment");
			maskh = (maskh << sector) | (maskl >> (32 - sector));
			maskl = maskl << sector;
			save_flags_cli(flags);
			if (((dma_malloc_freelist[page].l & maskl) != maskl) ||
			    ((dma_malloc_freelist[page].h & maskh) != maskh))
				panic("scsi_free:Trying to free unused memory");
			scsi_dma_free_sectors += nbits;
			dma_malloc_freelist[page].l &= ~maskl;
			dma_malloc_freelist[page].h &= ~maskh;
			restore_flags(flags);
			return 0;
		}
	}
	panic("scsi_free:Bad offset");
}
#endif


/*
 * Function:    scsi_resize_dma_pool
 *
 * Purpose:     Ensure that the DMA pool is sufficiently large to be
 *              able to guarantee that we can always process I/O requests
 *              without calling the system allocator.