[RFC 1/1] platform: IOMMU'able platform_device w/PLATFORM_ENABLE_IOMMU

[Hiroshi Doyu]

Introduced a new kernel config option, PLATFORM_ENABLE_IOMMU. With
this, all platform devices can be converted to be IOMMU'able if
platform_bus has non-null dma_iommu_map, where H/Ws always see its IO
virtual address and virt_to_phys() doesn't work from H/W POV.

Signed-off-by: Hiroshi Doyu <hdoyu@xxxxxxxxxx>
---
 arch/arm/mm/dma-mapping.c |    7 +++++++
 drivers/base/Kconfig      |    4 ++++
 drivers/base/platform.c   |   17 +++++++++++++++--
 drivers/iommu/Kconfig     |    2 +-
 include/linux/device.h    |    5 ++++-
 5 files changed, 31 insertions(+), 4 deletions(-)

diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c
index 242289f..28ca7c2 100644
--- a/arch/arm/mm/dma-mapping.c
+++ b/arch/arm/mm/dma-mapping.c
@@ -1899,6 +1899,13 @@ arm_iommu_create_mapping(struct bus_type *bus, dma_addr_t base, size_t size,
 	mapping->order = order;
 	spin_lock_init(&mapping->lock);

+#ifdef CONFIG_PLATFORM_ENABLE_IOMMU
+	if (WARN_ON(bus->map))
+		goto err3;
+
+	bus->map = mapping;
+#endif
+
 	mapping->domain = iommu_domain_alloc(bus);
 	if (!mapping->domain)
 		goto err3;
diff --git a/drivers/base/Kconfig b/drivers/base/Kconfig
index 3df339c..0f45311 100644
--- a/drivers/base/Kconfig
+++ b/drivers/base/Kconfig
@@ -308,4 +308,8 @@ config CMA_AREAS

 endif

+config PLATFORM_ENABLE_IOMMU
+        bool "Make platform devices iommuable"
+	depends on IOMMU_API
+
 endmenu
diff --git a/drivers/base/platform.c b/drivers/base/platform.c
index a1a7225..9eae3be 100644
--- a/drivers/base/platform.c
+++ b/drivers/base/platform.c
@@ -21,6 +21,8 @@
 #include <linux/slab.h>
 #include <linux/pm_runtime.h>

+#include <asm/dma-iommu.h>
+
 #include "base.h"

 #define to_platform_driver(drv)	(container_of((drv), struct platform_driver, \
@@ -305,8 +307,19 @@ int platform_device_add(struct platform_device *pdev)
 		 dev_name(&pdev->dev), dev_name(pdev->dev.parent));

 	ret = device_add(&pdev->dev);
-	if (ret == 0)
-		return ret;
+	if (ret)
+		goto failed;
+
+#ifdef CONFIG_PLATFORM_ENABLE_IOMMU
+	if (platform_bus_type.map && !pdev->dev.archdata.mapping) {
+		ret = arm_iommu_attach_device(&pdev->dev,
+					      platform_bus_type.map);
+		if (ret)
+			goto failed;
+	}
+#endif
+
+	return 0;

  failed:
 	while (--i >= 0) {
diff --git a/drivers/iommu/Kconfig b/drivers/iommu/Kconfig
index b736809..8b7eca1 100644
--- a/drivers/iommu/Kconfig
+++ b/drivers/iommu/Kconfig
@@ -164,7 +164,7 @@ config TEGRA_IOMMU_SMMU

 config TEGRA_IOMMU_SMMU_LINEAR
 	bool "Physical RAM IOVA Liner Mapping Support"
-	depends on TEGRA_IOMMU_SMMU
+	depends on TEGRA_IOMMU_SMMU && !PLATFORM_ENABLE_IOMMU
 	default y
 	help
 	  Enables support for linear mapping between physical address
diff --git a/include/linux/device.h b/include/linux/device.h
index e339929..3dcb501 100644
--- a/include/linux/device.h
+++ b/include/linux/device.h
@@ -35,6 +35,7 @@ struct subsys_private;
 struct bus_type;
 struct device_node;
 struct iommu_ops;
+struct dma_iommu_mapping;

 struct bus_attribute {
 	struct attribute	attr;
@@ -106,7 +107,9 @@ struct bus_type {
 	const struct dev_pm_ops *pm;

 	struct iommu_ops *iommu_ops;
-
+#ifdef CONFIG_PLATFORM_ENABLE_IOMMU
+	struct dma_iommu_mapping *map;
+#endif
 	struct subsys_private *p;
 };
--
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