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>

3 files changed, 45 insertions, 67 deletions

diff --git a/arch/x86/kernel/pci-dma.c b/arch/x86/kernel/pci-dma.c
index 48cccbe51aa5..7d3bd652c36f 100644
--- a/arch/x86/kernel/pci-dma.c
+++ b/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
diff --git a/arch/x86/kernel/pci-dma_32.c b/arch/x86/kernel/pci-dma_32.c
index 6543bb30b65d..1d4091af4417 100644
--- a/arch/x86/kernel/pci-dma_32.c
+++ b/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")) {
diff --git a/arch/x86/kernel/pci-dma_64.c b/arch/x86/kernel/pci-dma_64.c
index 7820675a688a..c80da76e7e61 100644
--- a/arch/x86/kernel/pci-dma_64.c
+++ b/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.