drm/vram-helpers: Merge code into a single file

Most of the documentation was in an otherwise empty file, which was
probably just left from a previous clean-up effort. So move code and
documentation into a single file.

Signed-off-by: Thomas Zimmermann <[e-mail]>
Acked-by: Gerd Hoffmann <[e-mail]>
Acked-by: Sam Ravnborg <[e-mail]>
Link: https://patchwork.freedesktop.org/patch/msgid/[e-mail]

Documentation/gpu/drm-mm.rst

···
 .. kernel-doc:: drivers/gpu/drm/drm_gem_cma_helper.c
    :export:
 
-VRAM Helper Function Reference
-==============================
-
-.. kernel-doc:: drivers/gpu/drm/drm_vram_helper_common.c
-   :doc: overview
-
-.. kernel-doc:: include/drm/drm_gem_vram_helper.h
-   :internal:
-
 GEM VRAM Helper Functions Reference
 -----------------------------------
 

drivers/gpu/drm/Makefile

···
 drm-$(CONFIG_DEBUG_FS) += drm_debugfs.o drm_debugfs_crc.o
 drm-$(CONFIG_DRM_LOAD_EDID_FIRMWARE) += drm_edid_load.o
 
-drm_vram_helper-y := drm_gem_vram_helper.o \
-		     drm_vram_helper_common.o
+drm_vram_helper-y := drm_gem_vram_helper.o
 obj-$(CONFIG_DRM_VRAM_HELPER) += drm_vram_helper.o
 
 drm_ttm_helper-y := drm_gem_ttm_helper.o

drivers/gpu/drm/drm_gem_vram_helper.c

···
 // SPDX-License-Identifier: GPL-2.0-or-later
 
+#include <linux/module.h>
+
 #include <drm/drm_debugfs.h>
 #include <drm/drm_device.h>
 #include <drm/drm_drv.h>
···
 /**
  * DOC: overview
  *
- * This library provides a GEM buffer object that is backed by video RAM
- * (VRAM). It can be used for framebuffer devices with dedicated memory.
+ * This library provides &struct drm_gem_vram_object (GEM VRAM), a GEM
+ * buffer object that is backed by video RAM (VRAM). It can be used for
+ * framebuffer devices with dedicated memory.
  *
  * The data structure &struct drm_vram_mm and its helpers implement a memory
- * manager for simple framebuffer devices with dedicated video memory. Buffer
- * objects are either placed in video RAM or evicted to system memory. The rsp.
- * buffer object is provided by &struct drm_gem_vram_object.
+ * manager for simple framebuffer devices with dedicated video memory. GEM
+ * VRAM buffer objects are either placed in the video memory or remain evicted
+ * to system memory.
+ *
+ * With the GEM interface userspace applications create, manage and destroy
+ * graphics buffers, such as an on-screen framebuffer. GEM does not provide
+ * an implementation of these interfaces. It's up to the DRM driver to
+ * provide an implementation that suits the hardware. If the hardware device
+ * contains dedicated video memory, the DRM driver can use the VRAM helper
+ * library. Each active buffer object is stored in video RAM. Active
+ * buffer are used for drawing the current frame, typically something like
+ * the frame's scanout buffer or the cursor image. If there's no more space
+ * left in VRAM, inactive GEM objects can be moved to system memory.
+ *
+ * The easiest way to use the VRAM helper library is to call
+ * drm_vram_helper_alloc_mm(). The function allocates and initializes an
+ * instance of &struct drm_vram_mm in &struct drm_device.vram_mm . Use
+ * &DRM_GEM_VRAM_DRIVER to initialize &struct drm_driver and
+ * &DRM_VRAM_MM_FILE_OPERATIONS to initialize &struct file_operations;
+ * as illustrated below.
+ *
+ * .. code-block:: c
+ *
+ *	struct file_operations fops ={
+ *		.owner = THIS_MODULE,
+ *		DRM_VRAM_MM_FILE_OPERATION
+ *	};
+ *	struct drm_driver drv = {
+ *		.driver_feature = DRM_ ... ,
+ *		.fops = &fops,
+ *		DRM_GEM_VRAM_DRIVER
+ *	};
+ *
+ *	int init_drm_driver()
+ *	{
+ *		struct drm_device *dev;
+ *		uint64_t vram_base;
+ *		unsigned long vram_size;
+ *		int ret;
+ *
+ *		// setup device, vram base and size
+ *		// ...
+ *
+ *		ret = drm_vram_helper_alloc_mm(dev, vram_base, vram_size);
+ *		if (ret)
+ *			return ret;
+ *		return 0;
+ *	}
+ *
+ * This creates an instance of &struct drm_vram_mm, exports DRM userspace
+ * interfaces for GEM buffer management and initializes file operations to
+ * allow for accessing created GEM buffers. With this setup, the DRM driver
+ * manages an area of video RAM with VRAM MM and provides GEM VRAM objects
+ * to userspace.
+ *
+ * To clean up the VRAM memory management, call drm_vram_helper_release_mm()
+ * in the driver's clean-up code.
+ *
+ * .. code-block:: c
+ *
+ *	void fini_drm_driver()
+ *	{
+ *		struct drm_device *dev = ...;
+ *
+ *		drm_vram_helper_release_mm(dev);
+ *	}
+ *
+ * For drawing or scanout operations, buffer object have to be pinned in video
+ * RAM. Call drm_gem_vram_pin() with &DRM_GEM_VRAM_PL_FLAG_VRAM or
+ * &DRM_GEM_VRAM_PL_FLAG_SYSTEM to pin a buffer object in video RAM or system
+ * memory. Call drm_gem_vram_unpin() to release the pinned object afterwards.
+ *
+ * A buffer object that is pinned in video RAM has a fixed address within that
+ * memory region. Call drm_gem_vram_offset() to retrieve this value. Typically
+ * it's used to program the hardware's scanout engine for framebuffers, set
+ * the cursor overlay's image for a mouse cursor, or use it as input to the
+ * hardware's draing engine.
+ *
+ * To access a buffer object's memory from the DRM driver, call
+ * drm_gem_vram_kmap(). It (optionally) maps the buffer into kernel address
+ * space and returns the memory address. Use drm_gem_vram_kunmap() to
+ * release the mapping.
  */
 
 /*
···
 	return drm_vram_helper_mode_valid_internal(dev, mode, max_bpp);
 }
 EXPORT_SYMBOL(drm_vram_helper_mode_valid);
+
+MODULE_DESCRIPTION("DRM VRAM memory-management helpers");
+MODULE_LICENSE("GPL");

drivers/gpu/drm/drm_vram_helper_common.c

···
-// SPDX-License-Identifier: GPL-2.0-or-later
-
-#include <linux/module.h>
-
-/**
- * DOC: overview
- *
- * This library provides &struct drm_gem_vram_object (GEM VRAM), a GEM
- * buffer object that is backed by video RAM. It can be used for
- * framebuffer devices with dedicated memory. The video RAM is managed
- * by &struct drm_vram_mm (VRAM MM).
- *
- * With the GEM interface userspace applications create, manage and destroy
- * graphics buffers, such as an on-screen framebuffer. GEM does not provide
- * an implementation of these interfaces. It's up to the DRM driver to
- * provide an implementation that suits the hardware. If the hardware device
- * contains dedicated video memory, the DRM driver can use the VRAM helper
- * library. Each active buffer object is stored in video RAM. Active
- * buffer are used for drawing the current frame, typically something like
- * the frame's scanout buffer or the cursor image. If there's no more space
- * left in VRAM, inactive GEM objects can be moved to system memory.
- *
- * The easiest way to use the VRAM helper library is to call
- * drm_vram_helper_alloc_mm(). The function allocates and initializes an
- * instance of &struct drm_vram_mm in &struct drm_device.vram_mm . Use
- * &DRM_GEM_VRAM_DRIVER to initialize &struct drm_driver and
- * &DRM_VRAM_MM_FILE_OPERATIONS to initialize &struct file_operations;
- * as illustrated below.
- *
- * .. code-block:: c
- *
- *	struct file_operations fops ={
- *		.owner = THIS_MODULE,
- *		DRM_VRAM_MM_FILE_OPERATION
- *	};
- *	struct drm_driver drv = {
- *		.driver_feature = DRM_ ... ,
- *		.fops = &fops,
- *		DRM_GEM_VRAM_DRIVER
- *	};
- *
- *	int init_drm_driver()
- *	{
- *		struct drm_device *dev;
- *		uint64_t vram_base;
- *		unsigned long vram_size;
- *		int ret;
- *
- *		// setup device, vram base and size
- *		// ...
- *
- *		ret = drm_vram_helper_alloc_mm(dev, vram_base, vram_size);
- *		if (ret)
- *			return ret;
- *		return 0;
- *	}
- *
- * This creates an instance of &struct drm_vram_mm, exports DRM userspace
- * interfaces for GEM buffer management and initializes file operations to
- * allow for accessing created GEM buffers. With this setup, the DRM driver
- * manages an area of video RAM with VRAM MM and provides GEM VRAM objects
- * to userspace.
- *
- * To clean up the VRAM memory management, call drm_vram_helper_release_mm()
- * in the driver's clean-up code.
- *
- * .. code-block:: c
- *
- *	void fini_drm_driver()
- *	{
- *		struct drm_device *dev = ...;
- *
- *		drm_vram_helper_release_mm(dev);
- *	}
- *
- * For drawing or scanout operations, buffer object have to be pinned in video
- * RAM. Call drm_gem_vram_pin() with &DRM_GEM_VRAM_PL_FLAG_VRAM or
- * &DRM_GEM_VRAM_PL_FLAG_SYSTEM to pin a buffer object in video RAM or system
- * memory. Call drm_gem_vram_unpin() to release the pinned object afterwards.
- *
- * A buffer object that is pinned in video RAM has a fixed address within that
- * memory region. Call drm_gem_vram_offset() to retrieve this value. Typically
- * it's used to program the hardware's scanout engine for framebuffers, set
- * the cursor overlay's image for a mouse cursor, or use it as input to the
- * hardware's draing engine.
- *
- * To access a buffer object's memory from the DRM driver, call
- * drm_gem_vram_kmap(). It (optionally) maps the buffer into kernel address
- * space and returns the memory address. Use drm_gem_vram_kunmap() to
- * release the mapping.
- */
-
-MODULE_DESCRIPTION("DRM VRAM memory-management helpers");
-MODULE_LICENSE("GPL");