[PATCH] Calgary: allow compiling Calgary in but not using it by default

This patch makes it possible to compile Calgary in but not use it by
default. In this mode, use 'iommu=calgary' to activate it.

Signed-off-by: Muli Ben-Yehuda <muli@il.ibm.com>
Signed-off-by: Jon Mason <jdmason@kudzu.us>
Signed-off-by: Andi Kleen <ak@suse.de>

2 files changed, 14 insertions, 0 deletions

diff --git a/arch/x86_64/kernel/pci-calgary.c b/arch/x86_64/kernel/pci-calgary.c
index 8a1e4f35bc3c..0ddf29dae7e0 100644
--- a/arch/x86_64/kernel/pci-calgary.c
+++ b/arch/x86_64/kernel/pci-calgary.c
@@ -43,6 +43,12 @@
 #include <asm/dma.h>
 #include <asm/rio.h>
 
+#ifdef CONFIG_CALGARY_IOMMU_ENABLED_BY_DEFAULT
+int use_calgary __read_mostly = 1;
+#else
+int use_calgary __read_mostly = 0;
+#endif /* CONFIG_CALGARY_DEFAULT_ENABLED */
+
 #define PCI_DEVICE_ID_IBM_CALGARY 0x02a1
 #define PCI_VENDOR_DEVICE_ID_CALGARY \
         (PCI_VENDOR_ID_IBM | PCI_DEVICE_ID_IBM_CALGARY << 16)
@@ -1061,6 +1067,9 @@ void __init detect_calgary(void)
         if (swiotlb || no_iommu || iommu_detected)
                 return;
 
+        if (!use_calgary)
+                return;
+
         if (!early_pci_allowed())
                 return;
 
diff --git a/arch/x86_64/kernel/pci-dma.c b/arch/x86_64/kernel/pci-dma.c
index f8d857453f8a..683b7a5c1ab3 100644
--- a/arch/x86_64/kernel/pci-dma.c
+++ b/arch/x86_64/kernel/pci-dma.c
@@ -296,6 +296,11 @@ __init int iommu_setup(char *p)
                 gart_parse_options(p);
 #endif
 
+#ifdef CONFIG_CALGARY_IOMMU
+                if (!strncmp(p, "calgary", 7))
+                        use_calgary = 1;
+#endif /* CONFIG_CALGARY_IOMMU */
+
                 p += strcspn(p, ",");
                 if (*p == ',')
                         ++p;