Date: Fri, 30 Jan 2004 17:37:31 -0700
From: Deepak Saxena <dsaxena@plexity.net>
To: torvalds@osdl.org, akpm@osdl.org
Cc: greg@kroah.com, linux-kernel@vger.kernel.org
Subject: [PATCH 1/3] Replace pci_pool with generic dma_pool
Message-ID: <20040131003731.GB24967@plexity.net>
Reply-To: dsaxena@plexity.net
References: <20040131003205.GA24967@plexity.net>
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- Add dmapool.c to drivers/base
- Initialize struct device.dma_pools in device_initialize()

diff -Nru a/drivers/base/Makefile b/drivers/base/Makefile
--- a/drivers/base/Makefile	Fri Jan 30 12:20:30 2004
+++ b/drivers/base/Makefile	Fri Jan 30 12:20:30 2004
@@ -2,7 +2,7 @@
 
 obj-y			:= core.o sys.o interface.o bus.o \
 			   driver.o class.o class_simple.o platform.o \
-			   cpu.o firmware.o init.o map.o
+			   cpu.o firmware.o init.o map.o dmapool.o
 obj-y			+= power/
 obj-$(CONFIG_FW_LOADER)	+= firmware_class.o
 obj-$(CONFIG_NUMA)	+= node.o  memblk.o
diff -Nru a/drivers/base/core.c b/drivers/base/core.c
--- a/drivers/base/core.c	Fri Jan 30 12:20:30 2004
+++ b/drivers/base/core.c	Fri Jan 30 12:20:30 2004
@@ -197,6 +197,7 @@
 	INIT_LIST_HEAD(&dev->children);
 	INIT_LIST_HEAD(&dev->driver_list);
 	INIT_LIST_HEAD(&dev->bus_list);
+	INIT_LIST_HEAD(&dev->dma_pools);
 }
 
 /**
diff -Nru a/drivers/base/dmapool.c b/drivers/base/dmapool.c
--- /dev/null	Wed Dec 31 16:00:00 1969
+++ b/drivers/base/dmapool.c	Fri Jan 30 12:20:30 2004
@@ -0,0 +1,409 @@
+
+#include <linux/device.h>
+#include <linux/mm.h>
+#include <asm/io.h>		/* Needed for i386 to build */
+#include <asm/scatterlist.h>	/* Needed for i386 to build */
+#include <linux/dma-mapping.h>
+#include <linux/dmapool.h>
+#include <linux/slab.h>
+#include <linux/module.h>
+
+/*
+ * Pool allocator ... wraps the dma_alloc_coherent page allocator, so
+ * small blocks are easily used by drivers for bus mastering controllers.
+ * This should probably be sharing the guts of the slab allocator.
+ */
+
+struct dma_pool {	/* the pool */
+	struct list_head	page_list;
+	spinlock_t		lock;
+	size_t			blocks_per_page;
+	size_t			size;
+	struct device		*dev;
+	size_t			allocation;
+	char			name [32];
+	wait_queue_head_t	waitq;
+	struct list_head	pools;
+};
+
+struct dma_page {	/* cacheable header for 'allocation' bytes */
+	struct list_head	page_list;
+	void			*vaddr;
+	dma_addr_t		dma;
+	unsigned		in_use;
+	unsigned long		bitmap [0];
+};
+
+#define	POOL_TIMEOUT_JIFFIES	((100 /* msec */ * HZ) / 1000)
+#define	POOL_POISON_FREED	0xa7	/* !inuse */
+#define	POOL_POISON_ALLOCATED	0xa9	/* !initted */
+
+static DECLARE_MUTEX (pools_lock);
+
+static ssize_t
+show_pools (struct device *dev, char *buf)
+{
+	unsigned		temp, size;
+	char			*next;
+	struct list_head	*i, *j;
+
+	next = buf;
+	size = PAGE_SIZE;
+
+	temp = snprintf (next, size, "poolinfo - 0.1\n");
+	size -= temp;
+	next += temp;
+
+	down (&pools_lock);
+	list_for_each (i, &dev->dma_pools) {
+		struct dma_pool	*pool;
+		unsigned	pages = 0, blocks = 0;
+
+		pool = list_entry (i, struct dma_pool, pools);
+
+		list_for_each (j, &pool->page_list) {
+			struct dma_page	*page;
+
+			page = list_entry (j, struct dma_page, page_list);
+			pages++;
+			blocks += page->in_use;
+		}
+
+		/* per-pool info, no real statistics yet */
+		temp = snprintf (next, size, "%-16s %4u %4Zu %4Zu %2u\n",
+				pool->name,
+				blocks, pages * pool->blocks_per_page,
+				pool->size, pages);
+		size -= temp;
+		next += temp;
+	}
+	up (&pools_lock);
+
+	return PAGE_SIZE - size;
+}
+static DEVICE_ATTR (pools, S_IRUGO, show_pools, NULL);
+
+/**
+ * dma_pool_create - Creates a pool of consistent memory blocks, for dma.
+ * @name: name of pool, for diagnostics
+ * @dev: device that will be doing the DMA
+ * @size: size of the blocks in this pool.
+ * @align: alignment requirement for blocks; must be a power of two
+ * @allocation: returned blocks won't cross this boundary (or zero)
+ * Context: !in_interrupt()
+ *
+ * Returns a dma allocation pool with the requested characteristics, or
+ * null if one can't be created.  Given one of these pools, dma_pool_alloc()
+ * may be used to allocate memory.  Such memory will all have "consistent"
+ * DMA mappings, accessible by the device and its driver without using
+ * cache flushing primitives.  The actual size of blocks allocated may be
+ * larger than requested because of alignment.
+ *
+ * If allocation is nonzero, objects returned from dma_pool_alloc() won't
+ * cross that size boundary.  This is useful for devices which have
+ * addressing restrictions on individual DMA transfers, such as not crossing
+ * boundaries of 4KBytes.
+ */
+struct dma_pool *
+dma_pool_create (const char *name, struct device *dev,
+	size_t size, size_t align, size_t allocation)
+{
+	struct dma_pool		*retval;
+
+	if (align == 0)
+		align = 1;
+	if (size == 0)
+		return 0;
+	else if (size < align)
+		size = align;
+	else if ((size % align) != 0) {
+		size += align + 1;
+		size &= ~(align - 1);
+	}
+
+	if (allocation == 0) {
+		if (PAGE_SIZE < size)
+			allocation = size;
+		else
+			allocation = PAGE_SIZE;
+		// FIXME: round up for less fragmentation
+	} else if (allocation < size)
+		return 0;
+
+	if (!(retval = kmalloc (sizeof *retval, SLAB_KERNEL)))
+		return retval;
+
+	strlcpy (retval->name, name, sizeof retval->name);
+
+	retval->dev = dev;
+
+	INIT_LIST_HEAD (&retval->page_list);
+	spin_lock_init (&retval->lock);
+	retval->size = size;
+	retval->allocation = allocation;
+	retval->blocks_per_page = allocation / size;
+	init_waitqueue_head (&retval->waitq);
+
+	if (dev) {
+		down (&pools_lock);
+		if (list_empty (&dev->dma_pools))
+			device_create_file (dev, &dev_attr_pools);
+		/* note:  not currently insisting "name" be unique */
+		list_add (&retval->pools, &dev->dma_pools);
+		up (&pools_lock);
+	} else
+		INIT_LIST_HEAD (&retval->pools);
+
+	return retval;
+}
+
+
+static struct dma_page *
+pool_alloc_page (struct dma_pool *pool, int mem_flags)
+{
+	struct dma_page	*page;
+	int		mapsize;
+
+	mapsize = pool->blocks_per_page;
+	mapsize = (mapsize + BITS_PER_LONG - 1) / BITS_PER_LONG;
+	mapsize *= sizeof (long);
+
+	page = (struct dma_page *) kmalloc (mapsize + sizeof *page, mem_flags);
+	if (!page)
+		return 0;
+	page->vaddr = dma_alloc_coherent (pool->dev,
+					    pool->allocation,
+					    &page->dma,
+					    mem_flags);
+	if (page->vaddr) {
+		memset (page->bitmap, 0xff, mapsize);	// bit set == free
+#ifdef	CONFIG_DEBUG_SLAB
+		memset (page->vaddr, POOL_POISON_FREED, pool->allocation);
+#endif
+		list_add (&page->page_list, &pool->page_list);
+		page->in_use = 0;
+	} else {
+		kfree (page);
+		page = 0;
+	}
+	return page;
+}
+
+
+static inline int
+is_page_busy (int blocks, unsigned long *bitmap)
+{
+	while (blocks > 0) {
+		if (*bitmap++ != ~0UL)
+			return 1;
+		blocks -= BITS_PER_LONG;
+	}
+	return 0;
+}
+
+static void
+pool_free_page (struct dma_pool *pool, struct dma_page *page)
+{
+	dma_addr_t	dma = page->dma;
+
+#ifdef	CONFIG_DEBUG_SLAB
+	memset (page->vaddr, POOL_POISON_FREED, pool->allocation);
+#endif
+	dma_free_coherent (pool->dev, pool->allocation, page->vaddr, dma);
+	list_del (&page->page_list);
+	kfree (page);
+}
+
+
+/**
+ * dma_pool_destroy - destroys a pool of dma memory blocks.
+ * @pool: dma pool that will be destroyed
+ * Context: !in_interrupt()
+ *
+ * Caller guarantees that no more memory from the pool is in use,
+ * and that nothing will try to use the pool after this call.
+ */
+void
+dma_pool_destroy (struct dma_pool *pool)
+{
+	down (&pools_lock);
+	list_del (&pool->pools);
+	if (pool->dev && list_empty (&pool->dev->dma_pools))
+		device_remove_file (pool->dev, &dev_attr_pools);
+	up (&pools_lock);
+
+	while (!list_empty (&pool->page_list)) {
+		struct dma_page		*page;
+		page = list_entry (pool->page_list.next,
+				struct dma_page, page_list);
+		if (is_page_busy (pool->blocks_per_page, page->bitmap)) {
+			printk (KERN_ERR "dma_pool_destroy %s/%s, %p busy\n",
+				pool->dev ? pool->dev->bus_id : NULL,
+				pool->name, page->vaddr);
+			/* leak the still-in-use consistent memory */
+			list_del (&page->page_list);
+			kfree (page);
+		} else
+			pool_free_page (pool, page);
+	}
+
+	kfree (pool);
+}
+
+
+/**
+ * dma_pool_alloc - get a block of consistent memory
+ * @pool: dma pool that will produce the block
+ * @mem_flags: SLAB_KERNEL or SLAB_ATOMIC
+ * @handle: pointer to dma address of block
+ *
+ * This returns the kernel virtual address of a currently unused block,
+ * and reports its dma address through the handle.
+ * If such a memory block can't be allocated, null is returned.
+ */
+void *
+dma_pool_alloc (struct dma_pool *pool, int mem_flags, dma_addr_t *handle)
+{
+	unsigned long		flags;
+	struct list_head	*entry;
+	struct dma_page		*page;
+	int			map, block;
+	size_t			offset;
+	void			*retval;
+
+restart:
+	spin_lock_irqsave (&pool->lock, flags);
+	list_for_each (entry, &pool->page_list) {
+		int		i;
+		page = list_entry (entry, struct dma_page, page_list);
+		/* only cachable accesses here ... */
+		for (map = 0, i = 0;
+				i < pool->blocks_per_page;
+				i += BITS_PER_LONG, map++) {
+			if (page->bitmap [map] == 0)
+				continue;
+			block = ffz (~ page->bitmap [map]);
+			if ((i + block) < pool->blocks_per_page) {
+				clear_bit (block, &page->bitmap [map]);
+				offset = (BITS_PER_LONG * map) + block;
+				offset *= pool->size;
+				goto ready;
+			}
+		}
+	}
+	if (!(page = pool_alloc_page (pool, SLAB_ATOMIC))) {
+		if (mem_flags == SLAB_KERNEL) {
+			DECLARE_WAITQUEUE (wait, current);
+
+			current->state = TASK_INTERRUPTIBLE;
+			add_wait_queue (&pool->waitq, &wait);
+			spin_unlock_irqrestore (&pool->lock, flags);
+
+			schedule_timeout (POOL_TIMEOUT_JIFFIES);
+
+			remove_wait_queue (&pool->waitq, &wait);
+			goto restart;
+		}
+		retval = 0;
+		goto done;
+	}
+
+	clear_bit (0, &page->bitmap [0]);
+	offset = 0;
+ready:
+	page->in_use++;
+	retval = offset + page->vaddr;
+	*handle = offset + page->dma;
+#ifdef	CONFIG_DEBUG_SLAB
+	memset (retval, POOL_POISON_ALLOCATED, pool->size);
+#endif
+done:
+	spin_unlock_irqrestore (&pool->lock, flags);
+	return retval;
+}
+
+
+static struct dma_page *
+pool_find_page (struct dma_pool *pool, dma_addr_t dma)
+{
+	unsigned long		flags;
+	struct list_head	*entry;
+	struct dma_page		*page;
+
+	spin_lock_irqsave (&pool->lock, flags);
+	list_for_each (entry, &pool->page_list) {
+		page = list_entry (entry, struct dma_page, page_list);
+		if (dma < page->dma)
+			continue;
+		if (dma < (page->dma + pool->allocation))
+			goto done;
+	}
+	page = 0;
+done:
+	spin_unlock_irqrestore (&pool->lock, flags);
+	return page;
+}
+
+
+/**
+ * dma_pool_free - put block back into dma pool
+ * @pool: the dma pool holding the block
+ * @vaddr: virtual address of block
+ * @dma: dma address of block
+ *
+ * Caller promises neither device nor driver will again touch this block
+ * unless it is first re-allocated.
+ */
+void
+dma_pool_free (struct dma_pool *pool, void *vaddr, dma_addr_t dma)
+{
+	struct dma_page		*page;
+	unsigned long		flags;
+	int			map, block;
+
+	if ((page = pool_find_page (pool, dma)) == 0) {
+		printk (KERN_ERR "dma_pool_free %s/%s, %p/%lx (bad dma)\n",
+			pool->dev ? pool->dev->bus_id : NULL,
+			pool->name, vaddr, (unsigned long) dma);
+		return;
+	}
+
+	block = dma - page->dma;
+	block /= pool->size;
+	map = block / BITS_PER_LONG;
+	block %= BITS_PER_LONG;
+
+#ifdef	CONFIG_DEBUG_SLAB
+	if (((dma - page->dma) + (void *)page->vaddr) != vaddr) {
+		printk (KERN_ERR "dma_pool_free %s/%s, %p (bad vaddr)/%Lx\n",
+			pool->dev ? pool->dev->bus_id : NULL,
+			pool->name, vaddr, (unsigned long long) dma);
+		return;
+	}
+	if (page->bitmap [map] & (1UL << block)) {
+		printk (KERN_ERR "dma_pool_free %s/%s, dma %Lx already free\n",
+			pool->dev ? pool->dev->bus_id : NULL,
+			pool->name, (unsigned long long)dma);
+		return;
+	}
+	memset (vaddr, POOL_POISON_FREED, pool->size);
+#endif
+
+	spin_lock_irqsave (&pool->lock, flags);
+	page->in_use--;
+	set_bit (block, &page->bitmap [map]);
+	if (waitqueue_active (&pool->waitq))
+		wake_up (&pool->waitq);
+	/*
+	 * Resist a temptation to do
+	 *    if (!is_page_busy(bpp, page->bitmap)) pool_free_page(pool, page);
+	 * it is not interrupt safe. Better have empty pages hang around.
+	 */
+	spin_unlock_irqrestore (&pool->lock, flags);
+}
+
+
+EXPORT_SYMBOL (dma_pool_create);
+EXPORT_SYMBOL (dma_pool_destroy);
+EXPORT_SYMBOL (dma_pool_alloc);
+EXPORT_SYMBOL (dma_pool_free);


-- 
Deepak Saxena - dsaxena@plexity.net
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