x86: merge dma_supported

The code for both arches are very similar, so this patch merge them.
Signed-off-by: Glauber Costa <gcosta@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

arch/x86/kernel/pci-dma.c

@@ -14,6 +14,8 @@ EXPORT_SYMBOL(forbid_dac);
 const struct dma_mapping_ops *dma_ops;
 EXPORT_SYMBOL(dma_ops);
 
+int iommu_sac_force __read_mostly = 0;
+
 #ifdef CONFIG_IOMMU_DEBUG
 int panic_on_overflow __read_mostly = 1;
 int force_iommu __read_mostly = 1;
@@ -103,6 +105,48 @@ void __init pci_iommu_alloc(void)
 }
 #endif
 
+int dma_supported(struct device *dev, u64 mask)
+{
+#ifdef CONFIG_PCI
+	if (mask > 0xffffffff && forbid_dac > 0) {
+		printk(KERN_INFO "PCI: Disallowing DAC for device %s\n",
+				 dev->bus_id);
+		return 0;
+	}
+#endif
+
+	if (dma_ops->dma_supported)
+		return dma_ops->dma_supported(dev, mask);
+
+	/* Copied from i386. Doesn't make much sense, because it will
+	   only work for pci_alloc_coherent.
+	   The caller just has to use GFP_DMA in this case. */
+	if (mask < DMA_24BIT_MASK)
+		return 0;
+
+	/* Tell the device to use SAC when IOMMU force is on.  This
+	   allows the driver to use cheaper accesses in some cases.
+
+	   Problem with this is that if we overflow the IOMMU area and
+	   return DAC as fallback address the device may not handle it
+	   correctly.
+
+	   As a special case some controllers have a 39bit address
+	   mode that is as efficient as 32bit (aic79xx). Don't force
+	   SAC for these.  Assume all masks <= 40 bits are of this
+	   type. Normally this doesn't make any difference, but gives
+	   more gentle handling of IOMMU overflow. */
+	if (iommu_sac_force && (mask >= DMA_40BIT_MASK)) {
+		printk(KERN_INFO "%s: Force SAC with mask %Lx\n",
+				 dev->bus_id, mask);
+		return 0;
+	}
+
+	return 1;
+}
+EXPORT_SYMBOL(dma_supported);
+
+
 static int __init pci_iommu_init(void)
 {
 #ifdef CONFIG_CALGARY_IOMMU

arch/x86/kernel/pci-dma_32.c

@@ -155,30 +155,6 @@ void *dma_mark_declared_memory_occupied(struct device *dev,
 EXPORT_SYMBOL(dma_mark_declared_memory_occupied);
 
 #ifdef CONFIG_PCI
-/* Many VIA bridges seem to corrupt data for DAC. Disable it here */
-
-int
-dma_supported(struct device *dev, u64 mask)
-{
-	/*
-	 * we fall back to GFP_DMA when the mask isn't all 1s,
-	 * so we can't guarantee allocations that must be
-	 * within a tighter range than GFP_DMA..
-	 */
-	if (mask < 0x00ffffff)
-		return 0;
-
-	/* Work around chipset bugs */
-	if (forbid_dac > 0 && mask > 0xffffffffULL)
-		return 0;
-
-	if (dma_ops->dma_supported)
-		return dma_ops->dma_supported(dev, mask);
-
-	return 1;
-}
-EXPORT_SYMBOL(dma_supported);
-
 static int check_iommu(char *s)
 {
 	if (!strcmp(s, "usedac")) {

arch/x86/kernel/pci-dma_64.c

@@ -24,7 +24,7 @@ EXPORT_SYMBOL(bad_dma_address);
 int iommu_bio_merge __read_mostly = 0;
 EXPORT_SYMBOL(iommu_bio_merge);
 
-static int iommu_sac_force __read_mostly = 0;
+extern int iommu_sac_force;
 
 int no_iommu __read_mostly;
 /* Set this to 1 if there is a HW IOMMU in the system */
@@ -161,48 +161,6 @@ void dma_free_coherent(struct device *dev, size_t size,
 }
 EXPORT_SYMBOL(dma_free_coherent);
 
-int dma_supported(struct device *dev, u64 mask)
-{
-#ifdef CONFIG_PCI
-	if (mask > 0xffffffff && forbid_dac > 0) {
-
-
-
-		printk(KERN_INFO "PCI: Disallowing DAC for device %s\n", dev->bus_id);
-		return 0;
-	}
-#endif
-
-	if (dma_ops->dma_supported)
-		return dma_ops->dma_supported(dev, mask);
-
-	/* Copied from i386. Doesn't make much sense, because it will
-	   only work for pci_alloc_coherent.
-	   The caller just has to use GFP_DMA in this case. */
-        if (mask < DMA_24BIT_MASK)
-                return 0;
-
-	/* Tell the device to use SAC when IOMMU force is on.  This
-	   allows the driver to use cheaper accesses in some cases.
-
-	   Problem with this is that if we overflow the IOMMU area and
-	   return DAC as fallback address the device may not handle it
-	   correctly.
-
-	   As a special case some controllers have a 39bit address
-	   mode that is as efficient as 32bit (aic79xx). Don't force
-	   SAC for these.  Assume all masks <= 40 bits are of this
-	   type. Normally this doesn't make any difference, but gives
-	   more gentle handling of IOMMU overflow. */
-	if (iommu_sac_force && (mask >= DMA_40BIT_MASK)) {
-		printk(KERN_INFO "%s: Force SAC with mask %Lx\n", dev->bus_id,mask);
-		return 0;
-	}
-
-	return 1;
-}
-EXPORT_SYMBOL(dma_supported);
-
 /*
  * See <Documentation/x86_64/boot-options.txt> for the iommu kernel parameter
  * documentation.