s390/pci_dma: simplify dma address calculation

Simplify the code we use to calculate dma addresses by putting
everything related in a dma_alloc_address function. Also provide
a dma_free_address counterpart.

Signed-off-by: Sebastian Ott <sebott@linux.vnet.ibm.com>
Reviewed-by: Gerald Schaefer <gerald.schaefer@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

1 files changed, 18 insertions, 19 deletions

diff --git a/arch/s390/pci/pci_dma.c b/arch/s390/pci/pci_dma.c
index 658123961f42..12b58b6b7f79 100644
--- a/arch/s390/pci/pci_dma.c
+++ b/arch/s390/pci/pci_dma.c
@@ -230,34 +230,36 @@ static unsigned long __dma_alloc_iommu(struct device *dev,
                                 boundary_size, 0);
 }
 
-static unsigned long dma_alloc_iommu(struct device *dev, int size)
+static dma_addr_t dma_alloc_address(struct device *dev, int size)
 {
         struct zpci_dev *zdev = to_zpci(to_pci_dev(dev));
         unsigned long offset, flags;
-        int wrap = 0;
 
         spin_lock_irqsave(&zdev->iommu_bitmap_lock, flags);
         offset = __dma_alloc_iommu(dev, zdev->next_bit, size);
         if (offset == -1) {
                 /* wrap-around */
                 offset = __dma_alloc_iommu(dev, 0, size);
-                wrap = 1;
-        }
-
-        if (offset != -1) {
-                zdev->next_bit = offset + size;
-                if (!zdev->tlb_refresh && !s390_iommu_strict && wrap)
+                if (offset == -1) {
+                        spin_unlock_irqrestore(&zdev->iommu_bitmap_lock, flags);
+                        return DMA_ERROR_CODE;
+                }
+                if (!zdev->tlb_refresh && !s390_iommu_strict)
                         /* global flush after wrap-around with lazy unmap */
                         zpci_refresh_global(zdev);
         }
+        zdev->next_bit = offset + size;
         spin_unlock_irqrestore(&zdev->iommu_bitmap_lock, flags);
-        return offset;
+
+        return zdev->start_dma + offset * PAGE_SIZE;
 }
 
-static void dma_free_iommu(struct device *dev, unsigned long offset, int size)
+static void dma_free_address(struct device *dev, dma_addr_t dma_addr, int size)
 {
         struct zpci_dev *zdev = to_zpci(to_pci_dev(dev));
-        unsigned long flags;
+        unsigned long flags, offset;
+
+        offset = (dma_addr - zdev->start_dma) >> PAGE_SHIFT;
 
         spin_lock_irqsave(&zdev->iommu_bitmap_lock, flags);
         if (!zdev->iommu_bitmap)
@@ -289,23 +291,22 @@ static dma_addr_t s390_dma_map_pages(struct device *dev, struct page *page,
                                      unsigned long attrs)
 {
         struct zpci_dev *zdev = to_zpci(to_pci_dev(dev));
-        unsigned long nr_pages, iommu_page_index;
         unsigned long pa = page_to_phys(page) + offset;
         int flags = ZPCI_PTE_VALID;
+        unsigned long nr_pages;
         dma_addr_t dma_addr;
         int ret;
 
         /* This rounds up number of pages based on size and offset */
         nr_pages = iommu_num_pages(pa, size, PAGE_SIZE);
-        iommu_page_index = dma_alloc_iommu(dev, nr_pages);
-        if (iommu_page_index == -1) {
+        dma_addr = dma_alloc_address(dev, nr_pages);
+        if (dma_addr == DMA_ERROR_CODE) {
                 ret = -ENOSPC;
                 goto out_err;
         }
 
         /* Use rounded up size */
         size = nr_pages * PAGE_SIZE;
-        dma_addr = zdev->start_dma + iommu_page_index * PAGE_SIZE;
 
         if (direction == DMA_NONE || direction == DMA_TO_DEVICE)
                 flags |= ZPCI_TABLE_PROTECTED;
@@ -318,7 +319,7 @@ static dma_addr_t s390_dma_map_pages(struct device *dev, struct page *page,
         return dma_addr + (offset & ~PAGE_MASK);
 
 out_free:
-        dma_free_iommu(dev, iommu_page_index, nr_pages);
+        dma_free_address(dev, dma_addr, nr_pages);
 out_err:
         zpci_err("map error:\n");
         zpci_err_dma(ret, pa);
@@ -330,7 +331,6 @@ static void s390_dma_unmap_pages(struct device *dev, dma_addr_t dma_addr,
                                  unsigned long attrs)
 {
         struct zpci_dev *zdev = to_zpci(to_pci_dev(dev));
-        unsigned long iommu_page_index;
         int npages, ret;
 
         npages = iommu_num_pages(dma_addr, size, PAGE_SIZE);
@@ -344,8 +344,7 @@ static void s390_dma_unmap_pages(struct device *dev, dma_addr_t dma_addr,
         }
 
         atomic64_add(npages, &zdev->unmapped_pages);
-        iommu_page_index = (dma_addr - zdev->start_dma) >> PAGE_SHIFT;
-        dma_free_iommu(dev, iommu_page_index, npages);
+        dma_free_address(dev, dma_addr, npages);
 }
 
 static void *s390_dma_alloc(struct device *dev, size_t size,