blackfin: use bitmap library functions

The bitmap library provides more efficient functions than accessing
individual bits with bitops.

This uses bitmap_find_next_zero_area() to find a continuing zero area,
and uses bitmap_set()/bitmap_clear() to set/clear specified bit area.

Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Cc: Mike Frysinger <vapier@gentoo.org>
Cc: uclinux-dist-devel@blackfin.uclinux.org
Signed-off-by: Bob Liu <lliubbo@gmail.com>

arch/blackfin/kernel/dma-mapping.c

@@ -13,6 +13,7 @@
 #include <linux/dma-mapping.h>
 #include <linux/scatterlist.h>
 #include <linux/export.h>
+#include <linux/bitmap.h>
 
 static spinlock_t dma_page_lock;
 static unsigned long *dma_page;
@@ -46,24 +47,17 @@ static inline unsigned int get_pages(size_t size)
 static unsigned long __alloc_dma_pages(unsigned int pages)
 {
 	unsigned long ret = 0, flags;
-	int i, count = 0;
+	unsigned long start;
 
 	if (dma_initialized == 0)
 		dma_alloc_init(_ramend - DMA_UNCACHED_REGION, _ramend);
 
 	spin_lock_irqsave(&dma_page_lock, flags);
 
-	for (i = 0; i < dma_pages;) {
-		if (test_bit(i++, dma_page) == 0) {
-			if (++count == pages) {
-				while (count--)
-					__set_bit(--i, dma_page);
-
-				ret = dma_base + (i << PAGE_SHIFT);
-				break;
-			}
-		} else
-			count = 0;
+	start = bitmap_find_next_zero_area(dma_page, dma_pages, 0, pages, 0);
+	if (start < dma_pages) {
+		ret = dma_base + (start << PAGE_SHIFT);
+		bitmap_set(dma_page, start, pages);
 	}
 	spin_unlock_irqrestore(&dma_page_lock, flags);
 	return ret;
@@ -73,17 +67,14 @@ static void __free_dma_pages(unsigned long addr, unsigned int pages)
 {
 	unsigned long page = (addr - dma_base) >> PAGE_SHIFT;
 	unsigned long flags;
-	int i;
 
 	if ((page + pages) > dma_pages) {
 		printk(KERN_ERR "%s: freeing outside range.\n", __func__);
 		BUG();
 	}
 
 	spin_lock_irqsave(&dma_page_lock, flags);
-	for (i = page; i < page + pages; i++)
-		__clear_bit(i, dma_page);
-
+	bitmap_clear(dma_page, page, pages);
 	spin_unlock_irqrestore(&dma_page_lock, flags);
 }