drm/exynos: use real device for DMA-mapping operations

This patch changes device pointer provided to all calls to DMA-mapping
subsystem from the virtual exynos-drm 'device' to the real device pointer
of one of the CRTC devices (decon, fimd or mixer). This way no more hacks
will be needed to configure proper DMA-mapping address space on the common
virtual exynos-drm device. This change also removes the need for some
hacks in IOMMU related code. It also finally solves the problem of Exynos
DRM driver not working on ARM64 architecture, which provides noop-based
DMA-mapping operations for virtual platform devices.

Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Inki Dae <inki.dae@samsung.com>

1 files changed, 38 insertions, 4 deletions

diff --git a/drivers/gpu/drm/exynos/exynos_drm_drv.c b/drivers/gpu/drm/exynos/exynos_drm_drv.c
index 7318c9ac8910..0dcfa04830ea 100644
--- a/drivers/gpu/drm/exynos/exynos_drm_drv.c
+++ b/drivers/gpu/drm/exynos/exynos_drm_drv.c
@@ -130,6 +130,8 @@ static void exynos_drm_atomic_work(struct work_struct *work)
 	exynos_atomic_commit_complete(commit);
 }
 
+static struct device *exynos_drm_get_dma_device(void);
+
 static int exynos_drm_load(struct drm_device *dev, unsigned long flags)
 {
 	struct exynos_drm_private *private;
@@ -147,6 +149,16 @@ static int exynos_drm_load(struct drm_device *dev, unsigned long flags)
 	dev_set_drvdata(dev->dev, dev);
 	dev->dev_private = (void *)private;
 
+	/* the first real CRTC device is used for all dma mapping operations */
+	private->dma_dev = exynos_drm_get_dma_device();
+	if (!private->dma_dev) {
+		DRM_ERROR("no device found for DMA mapping operations.\n");
+		ret = -ENODEV;
+		goto err_free_private;
+	}
+	DRM_INFO("Exynos DRM: using %s device for DMA mapping operations\n",
+		 dev_name(private->dma_dev));
+
 	/*
 	 * create mapping to manage iommu table and set a pointer to iommu
 	 * mapping structure to iommu_mapping of private data.
@@ -488,6 +500,7 @@ struct exynos_drm_driver_info {
 
 #define DRM_COMPONENT_DRIVER	BIT(0)	/* supports component framework */
 #define DRM_VIRTUAL_DEVICE	BIT(1)	/* create virtual platform device */
+#define DRM_DMA_DEVICE		BIT(2)	/* can be used for dma allocations */
 
 #define DRV_PTR(drv, cond) (IS_ENABLED(cond) ? &drv : NULL)
 
@@ -498,16 +511,16 @@ struct exynos_drm_driver_info {
 static struct exynos_drm_driver_info exynos_drm_drivers[] = {
 	{
 		DRV_PTR(fimd_driver, CONFIG_DRM_EXYNOS_FIMD),
-		DRM_COMPONENT_DRIVER
+		DRM_COMPONENT_DRIVER | DRM_DMA_DEVICE
 	}, {
 		DRV_PTR(exynos5433_decon_driver, CONFIG_DRM_EXYNOS5433_DECON),
-		DRM_COMPONENT_DRIVER
+		DRM_COMPONENT_DRIVER | DRM_DMA_DEVICE
 	}, {
 		DRV_PTR(decon_driver, CONFIG_DRM_EXYNOS7_DECON),
-		DRM_COMPONENT_DRIVER
+		DRM_COMPONENT_DRIVER | DRM_DMA_DEVICE
 	}, {
 		DRV_PTR(mixer_driver, CONFIG_DRM_EXYNOS_MIXER),
-		DRM_COMPONENT_DRIVER
+		DRM_COMPONENT_DRIVER | DRM_DMA_DEVICE
 	}, {
 		DRV_PTR(mic_driver, CONFIG_DRM_EXYNOS_MIC),
 		DRM_COMPONENT_DRIVER
@@ -615,6 +628,27 @@ static struct platform_driver exynos_drm_platform_driver = {
 	},
 };
 
+static struct device *exynos_drm_get_dma_device(void)
+{
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(exynos_drm_drivers); ++i) {
+		struct exynos_drm_driver_info *info = &exynos_drm_drivers[i];
+		struct device *dev;
+
+		if (!info->driver || !(info->flags & DRM_DMA_DEVICE))
+			continue;
+
+		while ((dev = bus_find_device(&platform_bus_type, NULL,
+					    &info->driver->driver,
+					    (void *)platform_bus_type.match))) {
+			put_device(dev);
+			return dev;
+		}
+	}
+	return NULL;
+}
+
 static void exynos_drm_unregister_devices(void)
 {
 	int i;