pcibuf.c.new

linux和2410结合开发 用他可以生成2410所需的zImage文件

/*
 *  linux/arch/arm/mach-s3c2410/pcibuf.c
 *
 *  Special pci_{map/unmap/dma_sync}_* routines for S3C2410.
 *
 *  These functions utilize bouncer buffers to compensate for a bug in
 *  the S3C2410 hardware which don't allow DMA to/from addresses
 *  certain addresses above 1MB.
 *
 *  Re-written by kingmonkey <[e-mail]>
 *  Re-written by Christopher Hoover <[e-mail]>
 *  Original version by Brad Parker ([e-mail])
 *
 *  Copyright (C) 2002 Hewlett Packard Company.
 *
 *  This program is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU General Public License
 *  version 2 as published by the Free Software Foundation.
 * */

#include <linux/module.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/pci.h>
#include <linux/list.h>

#include "pcipool.h"

//#define PCI_BUF_DEBUG 1

/*
 * 26 bits of the S3C2410 address bus are available to the S3C2410.
 * Use these when feeding target addresses to the DMA engines.
 */

#define S3C2410_ADDR_WIDTH	(26)
#define S3C2410_ADDR_MASK		((1<<S3C2410_ADDR_WIDTH)-1)
#define S3C2410_DMA_ADDR(x)	((x)&S3C2410_ADDR_MASK)


struct safe_buffer {
	struct list_head node;

	/* original request */
	void		*ptr;
	size_t		size;
	int		direction;

	/* safe buffer info */
	struct pci_pool *pool;
	void		*safe;
	dma_addr_t	safe_dma_addr;
};

LIST_HEAD(safe_buffers);

#define SIZE_SMALL	1024
#define SIZE_LARGE	(16*1024)

static struct pci_pool *small_buffer_pool, *large_buffer_pool;

static int
init_safe_buffers()
{
	small_buffer_pool = pci_pool_create("pci_small_buffer",
					    S3C2410_FAKE_PCIDEV,
					    SIZE_SMALL,
					    0 /* byte alignment */,
					    0 /* no page-crossing issues */,
					    GFP_KERNEL | GFP_DMA);

	if (small_buffer_pool == 0){
		printk(KERN_ERR"%s: could not allocate small pci pool\n", __func__);
		return -1;
	}

	large_buffer_pool = pci_pool_create("pci_large_buffer",
					    S3C2410_FAKE_PCIDEV,
					    SIZE_LARGE,
					    0 /* byte alignment */,
					    0 /* no page-crossing issues */,
					    GFP_KERNEL | GFP_DMA);
	if (large_buffer_pool == 0){
		printk(KERN_ERR"%s: could not allocate large pci pool\n", __func__);
		pci_pool_destroy(small_buffer_pool);		
		small_buffer_pool = 0;
		return -1;
	}

	return 0;
}

static void __exit
destroy_safe_buffer_pools(void)
{
	if (small_buffer_pool)
		pci_pool_destroy(small_buffer_pool);
	if (large_buffer_pool)
		pci_pool_destroy(large_buffer_pool);

	small_buffer_pool = large_buffer_pool = 0;
}


/* allocate a 'safe' buffer and keep track of it */
static struct safe_buffer *
alloc_safe_buffer(void *ptr, size_t size, int direction)
{
	struct safe_buffer *buf;
	struct pci_pool *pool;
	void *safe;
	dma_addr_t safe_dma_addr;

#ifdef PCI_BUF_DEBUG
	printk("%s: alloc_safe_buffer(size=%d)\n", __func__, size);
#endif

	buf = kmalloc(sizeof(struct safe_buffer), GFP_ATOMIC);
	if (buf == 0) {
		printk(KERN_WARNING "%s: kmalloc failed\n", __func__);
		return 0;
	}

	if (size <= SIZE_SMALL) {
		pool = small_buffer_pool;
		safe = pci_pool_alloc(pool, GFP_ATOMIC, &safe_dma_addr);
	} else if (size <= SIZE_LARGE) {
		pool = large_buffer_pool;
		safe = pci_pool_alloc(pool, GFP_ATOMIC, &safe_dma_addr);
	} else {
#ifdef PCI_BUF_DEBUG
		printk(KERN_DEBUG "%s: resorting to pci_alloc_consistent\n"__func__);
#endif
		pool = 0;
		safe = pci_alloc_consistent(S3C2410_FAKE_PCIDEV, size,&safe_dma_addr);
	}

	if (safe == 0) {
		printk(KERN_WARNING"%s: could not alloc dma memory (size=%d)\n",__func__, size);
		kfree(buf);
		return 0;
	}


	buf->ptr = ptr;
	buf->size = size;
	buf->direction = direction;
	buf->pool = pool;
	buf->safe = safe;
	buf->safe_dma_addr = safe_dma_addr;

	MOD_INC_USE_COUNT;
	list_add(&buf->node, &safe_buffers);

	return buf;
}

/* determine if a buffer is from our "safe" pool */
static struct safe_buffer *
find_safe_buffer(dma_addr_t safe_dma_addr)
{
	struct list_head *entry;

	list_for_each(entry, &safe_buffers) {
		struct safe_buffer *b =	list_entry(entry, struct safe_buffer, node);

		if (b->safe_dma_addr == safe_dma_addr) {
			return b;
		}
	}

	return 0;
}

static void
free_safe_buffer(struct safe_buffer *buf)
{

#ifdef PCI_BUF_DEBUG
	printk("%s: free_safe_buffer(buf=%p)\n", __func__,buf);
#endif
	
	list_del(&buf->node);
	if (buf->pool)
		pci_pool_free(buf->pool, buf->safe, buf->safe_dma_addr);
	else
		pci_free_consistent(S3C2410_FAKE_PCIDEV, buf->size, buf->safe,
				    buf->safe_dma_addr);
	kfree(buf);

	MOD_DEC_USE_COUNT;
}

static inline int
dma_range_is_safe(dma_addr_t addr, size_t size)
{
	unsigned int physaddr = S3C2410_DMA_ADDR((unsigned int) addr );

	/* Any address within one megabyte of the start of the target
         * bank will be OK.  This is an overly conservative test:
         * other addresses can be OK depending on the dram
         * configuration.  
	 *
	 * We take care to ensure the entire dma region is within
	 * the safe range.
	 */
	
	return ((physaddr + size - 1) < (1<<20));
}

/*
 * see if a buffer address is in an 'unsafe' range.  if it is
 * allocate a 'safe' buffer and copy the unsafe buffer into it.
 * substitute the safe buffer for the unsafe one.
 * (basically move the buffer from an unsafe area to a safe one)
 *
 * we assume calls to map_single are symmetric with calls to unmap_single...
 */
dma_addr_t
s3c2410_map_single(struct pci_dev *hwdev, void *virtptr,
	       size_t size, int direction)
{
	unsigned long flags;
	dma_addr_t dma_addr;


#ifdef PCI_BUF_DEBUG
	printk("%s: pci_map_single(hwdev=%p,ptr=%p,size=%d,dir=%x)  \n",
		      __func__,hwdev, virtptr, size, direction);
#endif
	local_irq_save(flags);

	dma_addr = virt_to_bus(virtptr);

	/* we assume here that a buffer will never be >=64k */
//	if ( (((unsigned long)dma_addr) & 0x100000) ||
//	     ((((unsigned long)dma_addr)+size) & 0x100000) )
	if(!dma_range_is_safe(dma_addr, size))
	{
		struct safe_buffer *buf;

		buf = alloc_safe_buffer(virtptr, size, direction);
		if (buf == 0) {
			printk(KERN_ERR
			       "%s: unable to map unsafe buffer %p!\n",
			       __func__, virtptr);
			local_irq_restore(flags);
			return 0;
		}

#ifdef PCI_BUF_DEBUG
		printk("%s: unsafe buffer %p (phy=%p) mapped to %p (phy=%p)\n",
			__func__,
			buf->ptr, (void *) virt_to_bus(buf->ptr),
			buf->safe, (void *) buf->safe_dma_addr);
#endif

		if ((direction == PCI_DMA_TODEVICE) ||(direction == PCI_DMA_BIDIRECTIONAL)) {
#ifdef PCI_BUF_DEBUG	 
			printk("%s: copy out from unsafe %p, to safe %p, size %d\n",__func__, virtptr, buf->safe, size);
#endif
			memcpy(buf->safe, virtptr, size);
		}
		consistent_sync(buf->safe, size, direction);

	} else {
		consistent_sync(virtptr, size, direction);
	}

	local_irq_restore(flags);
	return dma_addr;
}

/*
 * see if a mapped address was really a "safe" buffer and if so,
 * copy the data from the safe buffer back to the unsafe buffer
 * and free up the safe buffer.
 * (basically return things back to the way they should be)
 */
void
s3c2410_unmap_single(struct pci_dev *hwdev, dma_addr_t dma_addr,
		 size_t size, int direction)
{
	unsigned long flags;
	struct safe_buffer *buf;
	void *tmp;
#ifdef PCI_BUF_DEBUG
	printk("%s(ptr=%p,size=%d,dir=%x)\n",
		__func__, (void *) dma_addr, size, direction);
#endif

	if(direction == PCI_DMA_NONE)
		BUG();

	local_irq_save(flags);

	buf = find_safe_buffer(dma_addr);
	if (buf) {
		if(buf->size != size)
			BUG();
		if(buf->direction != direction)
			BUG();
#ifdef PCI_BUF_DEBUG
		printk("%s: unsafe buffer %p (phy=%p) mapped to %p (phy=%p)\n",
			__func__,
			buf->ptr, (void *) virt_to_bus(buf->ptr),
			buf->safe, (void *) buf->safe_dma_addr);
#endif
		if ((direction == PCI_DMA_FROMDEVICE) ||
		    (direction == PCI_DMA_BIDIRECTIONAL)) {
#ifdef PCI_BUF_DEBUG		    
			printk("%s: copy back from safe %p, to unsafe %p size %d\n",
				__func__, buf->safe, buf->ptr, size);
#endif
			memcpy(buf->ptr, buf->safe, size);
			free_safe_buffer(buf);
		}
	}else	{
		/* assume this is normal memory */
		tmp = bus_to_virt(dma_addr);
		consistent_sync(tmp, size, PCI_DMA_FROMDEVICE);

	}
	local_irq_restore(flags);
}


EXPORT_SYMBOL(s3c2410_map_single);
EXPORT_SYMBOL(s3c2410_unmap_single);

static int __init s3c2410_init_safe_buffers(void)
{
	int ret;
	printk("Initializing S3C2410 buffer pool for DMA workaround\n");
	
	ret=init_safe_buffers();
	return ret;
}

static void __exit s3c2410_free_safe_buffers(void)
{
	if(!list_empty(&safe_buffers))
		BUG();
	destroy_safe_buffer_pools();
}

module_init(s3c2410_init_safe_buffers);
module_exit(s3c2410_free_safe_buffers);

MODULE_AUTHOR("kingmonkey <[e-mail]>");
MODULE_DESCRIPTION("Special pci_{map/unmap/dma_sync}_* routines for S3C2410	.");
MODULE_LICENSE("GPL");