[Intel-IOMMU 10/10] Iommu floppy workaround

[anil.s.keshavamurthy@intel.com]

	This config option (DMAR_FLPY_WA) sets up 1:1 mapping for the
floppy device so that the floppy device which does not use
DMA api's will continue to work.

Signed-off-by: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
---
 arch/x86_64/Kconfig       |   10 ++++++++++
 drivers/pci/intel-iommu.c |   23 +++++++++++++++++++++++
 2 files changed, 33 insertions(+)

Index: linux-2.6.22-rc3/arch/x86_64/Kconfig
===================================================================
--- linux-2.6.22-rc3.orig/arch/x86_64/Kconfig	2007-06-04 12:41:11.000000000 -0700
+++ linux-2.6.22-rc3/arch/x86_64/Kconfig	2007-06-04 12:41:23.000000000 -0700
@@ -738,6 +738,16 @@
 	 all the OS visible memory. Hence the driver can continue
 	 to use physical addresses for DMA.
 
+config DMAR_FLPY_WA
+	bool "Support for Floppy disk workaround"
+	depends on DMAR
+	default y
+	help
+	 Floppy disk drivers are know to by pass dma api calls
+	 their by failing to work when IOMMU is enabled. This
+	 work around will setup a 1 to 1 mappings for the first
+	 16M to make floppy(isa device) work.
+
 source "drivers/pci/pcie/Kconfig"
 
 source "drivers/pci/Kconfig"
Index: linux-2.6.22-rc3/drivers/pci/intel-iommu.c
===================================================================
--- linux-2.6.22-rc3.orig/drivers/pci/intel-iommu.c	2007-06-04 12:41:11.000000000 -0700
+++ linux-2.6.22-rc3/drivers/pci/intel-iommu.c	2007-06-04 12:41:23.000000000 -0700
@@ -1584,6 +1584,25 @@
 }
 #endif
 
+#ifdef CONFIG_DMAR_FLPY_WA
+static void iommu_prepare_isa(void)
+{
+	struct pci_dev *pdev = NULL;
+	int ret;
+
+	pdev = pci_get_class (PCI_CLASS_BRIDGE_ISA << 8, NULL);
+	if (!pdev)
+		return;
+
+	printk (KERN_INFO "IOMMU: Prepare 0-16M unity mapping for LPC\n");
+	ret = iommu_prepare_identity_map(pdev, 0, 16*1024*1024);
+
+	if (ret)
+		printk ("IOMMU: Failed to create 0-64M identity map, Floppy might not work\n");
+
+}
+#endif
+
 int __init init_dmars(void)
 {
 	struct dmar_drhd_unit *drhd;
@@ -1643,6 +1662,10 @@
 	iommu_prepare_gfx_mapping();
 #endif
 
+#ifdef CONFIG_DMAR_FLPY_WA
+	iommu_prepare_isa();
+#endif
+
 	/*
 	 * for each drhd
 	 *   enable fault log

-- 
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