diff mbox

drm: allow to use mmuless SoC

Message ID 1483714903-27892-1-git-send-email-benjamin.gaignard@linaro.org (mailing list archive)
State New, archived
Headers show

Commit Message

Benjamin Gaignard Jan. 6, 2017, 3:01 p.m. UTC 
Some SoC without MMU have display driver where a drm/kms driver
could be implemented.

Before doing such kind of thing drm/kms must allow to use mmuless devices.
This patch propose to remove MMU configuration flag and add a cma helper
function to help implementing mmuless display driver

version 4:
- add documentation about drm_gem_cma_get_unmapped_area()
- stub it MMU case

version 5:
- Make all driver that select DRM_TTM depends on MMU
  (issue reported by kbuild test robot)

Signed-off-by: Benjamin Gaignard <benjamin.gaignard@linaro.org>
[danvet: Use recommended struct member references in kernel-doc.]
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/1483521177-21794-4-git-send-email-benjamin.gaignard@linaro.org
---
 Documentation/gpu/drm-mm.rst            | 11 +++++
 drivers/gpu/drm/Kconfig                 |  8 ++--
 drivers/gpu/drm/ast/Kconfig             |  2 +-
 drivers/gpu/drm/bochs/Kconfig           |  2 +-
 drivers/gpu/drm/cirrus/Kconfig          |  2 +-
 drivers/gpu/drm/drm_gem_cma_helper.c    | 71 +++++++++++++++++++++++++++++++++
 drivers/gpu/drm/gma500/Kconfig          |  2 +-
 drivers/gpu/drm/hisilicon/hibmc/Kconfig |  2 +-
 drivers/gpu/drm/mgag200/Kconfig         |  2 +-
 drivers/gpu/drm/nouveau/Kconfig         |  2 +-
 drivers/gpu/drm/qxl/Kconfig             |  2 +-
 drivers/gpu/drm/virtio/Kconfig          |  2 +-
 drivers/gpu/drm/vmwgfx/Kconfig          |  2 +-
 include/drm/drm_gem_cma_helper.h        | 17 ++++++++
 14 files changed, 113 insertions(+), 14 deletions(-)
diff mbox

Patch

diff --git a/Documentation/gpu/drm-mm.rst b/Documentation/gpu/drm-mm.rst
index d3c6d77..1ea94fc 100644
--- a/Documentation/gpu/drm-mm.rst
+++ b/Documentation/gpu/drm-mm.rst
@@ -310,6 +310,17 @@  created.
 Drivers that want to map the GEM object upfront instead of handling page
 faults can implement their own mmap file operation handler.
 
+For platforms without MMU the GEM core provides a helper method
+:c:func:`drm_gem_cma_get_unmapped_area`. The mmap() routines will call
+this to get a proposed address for the mapping.
+
+To use :c:func:`drm_gem_cma_get_unmapped_area`, drivers must fill the
+struct :c:type:`struct file_operations <file_operations>` get_unmapped_area
+field with a pointer on :c:func:`drm_gem_cma_get_unmapped_area`.
+
+More detailed information about get_unmapped_area can be found in
+Documentation/nommu-mmap.txt
+
 Memory Coherency
 ----------------
 
diff --git a/drivers/gpu/drm/Kconfig b/drivers/gpu/drm/Kconfig
index d56b85c..6f3f9e6 100644
--- a/drivers/gpu/drm/Kconfig
+++ b/drivers/gpu/drm/Kconfig
@@ -6,7 +6,7 @@ 
 #
 menuconfig DRM
 	tristate "Direct Rendering Manager (XFree86 4.1.0 and higher DRI support)"
-	depends on (AGP || AGP=n) && !EMULATED_CMPXCHG && MMU && HAS_DMA
+	depends on (AGP || AGP=n) && !EMULATED_CMPXCHG && HAS_DMA
 	select HDMI
 	select FB_CMDLINE
 	select I2C
@@ -113,7 +113,7 @@  config DRM_LOAD_EDID_FIRMWARE
 
 config DRM_TTM
 	tristate
-	depends on DRM
+	depends on DRM && MMU
 	help
 	  GPU memory management subsystem for devices with multiple
 	  GPU memory types. Will be enabled automatically if a device driver
@@ -146,7 +146,7 @@  source "drivers/gpu/drm/arm/Kconfig"
 
 config DRM_RADEON
 	tristate "ATI Radeon"
-	depends on DRM && PCI
+	depends on DRM && PCI && MMU
 	select FW_LOADER
         select DRM_KMS_HELPER
         select DRM_TTM
@@ -166,7 +166,7 @@  source "drivers/gpu/drm/radeon/Kconfig"
 
 config DRM_AMDGPU
 	tristate "AMD GPU"
-	depends on DRM && PCI
+	depends on DRM && PCI && MMU
 	select FW_LOADER
         select DRM_KMS_HELPER
         select DRM_TTM
diff --git a/drivers/gpu/drm/ast/Kconfig b/drivers/gpu/drm/ast/Kconfig
index 15f6ce7..9647e1f 100644
--- a/drivers/gpu/drm/ast/Kconfig
+++ b/drivers/gpu/drm/ast/Kconfig
@@ -1,6 +1,6 @@ 
 config DRM_AST
 	tristate "AST server chips"
-	depends on DRM && PCI
+	depends on DRM && PCI && MMU
 	select DRM_TTM
 	select DRM_KMS_HELPER
 	select DRM_TTM
diff --git a/drivers/gpu/drm/bochs/Kconfig b/drivers/gpu/drm/bochs/Kconfig
index f739763..bd27180 100644
--- a/drivers/gpu/drm/bochs/Kconfig
+++ b/drivers/gpu/drm/bochs/Kconfig
@@ -1,6 +1,6 @@ 
 config DRM_BOCHS
 	tristate "DRM Support for bochs dispi vga interface (qemu stdvga)"
-	depends on DRM && PCI
+	depends on DRM && PCI && MMU
 	select DRM_KMS_HELPER
 	select DRM_TTM
 	help
diff --git a/drivers/gpu/drm/cirrus/Kconfig b/drivers/gpu/drm/cirrus/Kconfig
index 04b3c16..ca38098 100644
--- a/drivers/gpu/drm/cirrus/Kconfig
+++ b/drivers/gpu/drm/cirrus/Kconfig
@@ -1,6 +1,6 @@ 
 config DRM_CIRRUS_QEMU
 	tristate "Cirrus driver for QEMU emulated device"
-	depends on DRM && PCI
+	depends on DRM && PCI && MMU
 	select DRM_KMS_HELPER
 	select DRM_TTM
 	help
diff --git a/drivers/gpu/drm/drm_gem_cma_helper.c b/drivers/gpu/drm/drm_gem_cma_helper.c
index e0806a2a..5cf38a4 100644
--- a/drivers/gpu/drm/drm_gem_cma_helper.c
+++ b/drivers/gpu/drm/drm_gem_cma_helper.c
@@ -358,6 +358,77 @@  int drm_gem_cma_mmap(struct file *filp, struct vm_area_struct *vma)
 }
 EXPORT_SYMBOL_GPL(drm_gem_cma_mmap);
 
+#ifndef CONFIG_MMU
+/**
+ * drm_gem_cma_get_unmapped_area - propose address for mapping in noMMU cases
+ * @filp: file object
+ * @addr: memory address
+ * @len: buffer size
+ * @pgoff: page offset
+ * @flags: memory flags
+ *
+ * This function is used in noMMU platforms to propose address mapping
+ * for a given buffer.
+ * It's intended to be used as a direct handler for the struct
+ * &file_operations.get_unmapped_area operation.
+ *
+ * Returns:
+ * mapping address on success or a negative error code on failure.
+ */
+unsigned long drm_gem_cma_get_unmapped_area(struct file *filp,
+					    unsigned long addr,
+					    unsigned long len,
+					    unsigned long pgoff,
+					    unsigned long flags)
+{
+	struct drm_gem_cma_object *cma_obj;
+	struct drm_gem_object *obj = NULL;
+	struct drm_file *priv = filp->private_data;
+	struct drm_device *dev = priv->minor->dev;
+	struct drm_vma_offset_node *node;
+
+	if (drm_device_is_unplugged(dev))
+		return -ENODEV;
+
+	drm_vma_offset_lock_lookup(dev->vma_offset_manager);
+	node = drm_vma_offset_exact_lookup_locked(dev->vma_offset_manager,
+						  pgoff,
+						  len >> PAGE_SHIFT);
+	if (likely(node)) {
+		obj = container_of(node, struct drm_gem_object, vma_node);
+		/*
+		 * When the object is being freed, after it hits 0-refcnt it
+		 * proceeds to tear down the object. In the process it will
+		 * attempt to remove the VMA offset and so acquire this
+		 * mgr->vm_lock.  Therefore if we find an object with a 0-refcnt
+		 * that matches our range, we know it is in the process of being
+		 * destroyed and will be freed as soon as we release the lock -
+		 * so we have to check for the 0-refcnted object and treat it as
+		 * invalid.
+		 */
+		if (!kref_get_unless_zero(&obj->refcount))
+			obj = NULL;
+	}
+
+	drm_vma_offset_unlock_lookup(dev->vma_offset_manager);
+
+	if (!obj)
+		return -EINVAL;
+
+	if (!drm_vma_node_is_allowed(node, priv)) {
+		drm_gem_object_unreference_unlocked(obj);
+		return -EACCES;
+	}
+
+	cma_obj = to_drm_gem_cma_obj(obj);
+
+	drm_gem_object_unreference_unlocked(obj);
+
+	return cma_obj->vaddr ? (unsigned long)cma_obj->vaddr : -EINVAL;
+}
+EXPORT_SYMBOL_GPL(drm_gem_cma_get_unmapped_area);
+#endif
+
 #ifdef CONFIG_DEBUG_FS
 /**
  * drm_gem_cma_describe - describe a CMA GEM object for debugfs
diff --git a/drivers/gpu/drm/gma500/Kconfig b/drivers/gpu/drm/gma500/Kconfig
index 8906d67..df11582 100644
--- a/drivers/gpu/drm/gma500/Kconfig
+++ b/drivers/gpu/drm/gma500/Kconfig
@@ -1,6 +1,6 @@ 
 config DRM_GMA500
 	tristate "Intel GMA5/600 KMS Framebuffer"
-	depends on DRM && PCI && X86
+	depends on DRM && PCI && X86 && MMU
 	select DRM_KMS_HELPER
 	select DRM_TTM
 	# GMA500 depends on ACPI_VIDEO when ACPI is enabled, just like i915
diff --git a/drivers/gpu/drm/hisilicon/hibmc/Kconfig b/drivers/gpu/drm/hisilicon/hibmc/Kconfig
index 380622a..c7129dc 100644
--- a/drivers/gpu/drm/hisilicon/hibmc/Kconfig
+++ b/drivers/gpu/drm/hisilicon/hibmc/Kconfig
@@ -1,6 +1,6 @@ 
 config DRM_HISI_HIBMC
 	tristate "DRM Support for Hisilicon Hibmc"
-	depends on DRM && PCI
+	depends on DRM && PCI && MMU
 	select DRM_KMS_HELPER
 	select DRM_TTM
 
diff --git a/drivers/gpu/drm/mgag200/Kconfig b/drivers/gpu/drm/mgag200/Kconfig
index 520e5e6..db58578 100644
--- a/drivers/gpu/drm/mgag200/Kconfig
+++ b/drivers/gpu/drm/mgag200/Kconfig
@@ -1,6 +1,6 @@ 
 config DRM_MGAG200
 	tristate "Kernel modesetting driver for MGA G200 server engines"
-	depends on DRM && PCI
+	depends on DRM && PCI && MMU
 	select DRM_KMS_HELPER
 	select DRM_TTM
 	help
diff --git a/drivers/gpu/drm/nouveau/Kconfig b/drivers/gpu/drm/nouveau/Kconfig
index 0f2f0af..c02a134 100644
--- a/drivers/gpu/drm/nouveau/Kconfig
+++ b/drivers/gpu/drm/nouveau/Kconfig
@@ -1,6 +1,6 @@ 
 config DRM_NOUVEAU
 	tristate "Nouveau (NVIDIA) cards"
-	depends on DRM && PCI
+	depends on DRM && PCI && MMU
         select FW_LOADER
 	select DRM_KMS_HELPER
 	select DRM_TTM
diff --git a/drivers/gpu/drm/qxl/Kconfig b/drivers/gpu/drm/qxl/Kconfig
index da45b11..378da59 100644
--- a/drivers/gpu/drm/qxl/Kconfig
+++ b/drivers/gpu/drm/qxl/Kconfig
@@ -1,6 +1,6 @@ 
 config DRM_QXL
 	tristate "QXL virtual GPU"
-	depends on DRM && PCI
+	depends on DRM && PCI && MMU
 	select DRM_KMS_HELPER
 	select DRM_TTM
 	select CRC32
diff --git a/drivers/gpu/drm/virtio/Kconfig b/drivers/gpu/drm/virtio/Kconfig
index 81d1807..0c384d9 100644
--- a/drivers/gpu/drm/virtio/Kconfig
+++ b/drivers/gpu/drm/virtio/Kconfig
@@ -1,6 +1,6 @@ 
 config DRM_VIRTIO_GPU
 	tristate "Virtio GPU driver"
-	depends on DRM && VIRTIO
+	depends on DRM && VIRTIO && MMU
 	select DRM_KMS_HELPER
 	select DRM_TTM
 	help
diff --git a/drivers/gpu/drm/vmwgfx/Kconfig b/drivers/gpu/drm/vmwgfx/Kconfig
index fb7b82a..8c308da 100644
--- a/drivers/gpu/drm/vmwgfx/Kconfig
+++ b/drivers/gpu/drm/vmwgfx/Kconfig
@@ -1,6 +1,6 @@ 
 config DRM_VMWGFX
 	tristate "DRM driver for VMware Virtual GPU"
-	depends on DRM && PCI && X86
+	depends on DRM && PCI && X86 && MMU
 	select FB_DEFERRED_IO
 	select FB_CFB_FILLRECT
 	select FB_CFB_COPYAREA
diff --git a/include/drm/drm_gem_cma_helper.h b/include/drm/drm_gem_cma_helper.h
index acd6af8..2abcd51 100644
--- a/include/drm/drm_gem_cma_helper.h
+++ b/include/drm/drm_gem_cma_helper.h
@@ -53,6 +53,23 @@  struct drm_gem_cma_object *drm_gem_cma_create(struct drm_device *drm,
 
 extern const struct vm_operations_struct drm_gem_cma_vm_ops;
 
+#ifndef CONFIG_MMU
+unsigned long drm_gem_cma_get_unmapped_area(struct file *filp,
+					    unsigned long addr,
+					    unsigned long len,
+					    unsigned long pgoff,
+					    unsigned long flags);
+#else
+static inline unsigned long drm_gem_cma_get_unmapped_area(struct file *filp,
+							  unsigned long addr,
+							  unsigned long len,
+							  unsigned long pgoff,
+							  unsigned long flags)
+{
+	return -EINVAL;
+}
+#endif
+
 #ifdef CONFIG_DEBUG_FS
 void drm_gem_cma_describe(struct drm_gem_cma_object *obj, struct seq_file *m);
 #endif