// 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>
#include <drm/drm_file.h>
#include <drm/drm_framebuffer.h>
#include <drm/drm_gem_framebuffer_helper.h>
#include <drm/drm_gem_ttm_helper.h>
#include <drm/drm_gem_vram_helper.h>
#include <drm/drm_managed.h>
#include <drm/drm_mode.h>
#include <drm/drm_plane.h>
#include <drm/drm_prime.h>
#include <drm/drm_simple_kms_helper.h>
#include <drm/ttm/ttm_page_alloc.h>

static const struct drm_gem_object_funcs drm_gem_vram_object_funcs;

/**
 * DOC: overview
 *
 * 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. 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.
 *
 * To initialize the VRAM helper library call drmm_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 = drmm_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.
 *
 * You don't have to clean up the instance of VRAM MM.
 * drmm_vram_helper_alloc_mm() is a managed interface that installs a
 * clean-up handler to run during the DRM device's release.
 *
 * For drawing or scanout operations, rsp. buffer objects 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.
 */

/*
 * Buffer-objects helpers
 */

static void drm_gem_vram_cleanup(struct drm_gem_vram_object *gbo)
{
        /* We got here via ttm_bo_put(), which means that the
         * TTM buffer object in 'bo' has already been cleaned
         * up; only release the GEM object.
         */

        WARN_ON(gbo->kmap_use_count);
        WARN_ON(gbo->kmap.virtual);

        drm_gem_object_release(&gbo->bo.base);
}

static void drm_gem_vram_destroy(struct drm_gem_vram_object *gbo)
{
        drm_gem_vram_cleanup(gbo);
        kfree(gbo);
}

static void ttm_buffer_object_destroy(struct ttm_buffer_object *bo)
{
        struct drm_gem_vram_object *gbo = drm_gem_vram_of_bo(bo);

        drm_gem_vram_destroy(gbo);
}

static void drm_gem_vram_placement(struct drm_gem_vram_object *gbo,
                                   unsigned long pl_flag)
{
        unsigned int i;
        unsigned int c = 0;
        u32 invariant_flags = pl_flag & TTM_PL_FLAG_TOPDOWN;

        gbo->placement.placement = gbo->placements;
        gbo->placement.busy_placement = gbo->placements;

        if (pl_flag & TTM_PL_FLAG_VRAM)
                gbo->placements[c++].flags = TTM_PL_FLAG_WC |
                                             TTM_PL_FLAG_UNCACHED |
                                             TTM_PL_FLAG_VRAM |
                                             invariant_flags;

        if (pl_flag & TTM_PL_FLAG_SYSTEM)
                gbo->placements[c++].flags = TTM_PL_MASK_CACHING |
                                             TTM_PL_FLAG_SYSTEM |
                                             invariant_flags;

        if (!c)
                gbo->placements[c++].flags = TTM_PL_MASK_CACHING |
                                             TTM_PL_FLAG_SYSTEM |
                                             invariant_flags;

        gbo->placement.num_placement = c;
        gbo->placement.num_busy_placement = c;

        for (i = 0; i < c; ++i) {
                gbo->placements[i].fpfn = 0;
                gbo->placements[i].lpfn = 0;
        }
}

static int drm_gem_vram_init(struct drm_device *dev,
                             struct drm_gem_vram_object *gbo,
                             size_t size, unsigned long pg_align)
{
        struct drm_vram_mm *vmm = dev->vram_mm;
        struct ttm_bo_device *bdev;
        int ret;
        size_t acc_size;

        if (WARN_ONCE(!vmm, "VRAM MM not initialized"))
                return -EINVAL;
        bdev = &vmm->bdev;

        gbo->bo.base.funcs = &drm_gem_vram_object_funcs;

        ret = drm_gem_object_init(dev, &gbo->bo.base, size);
        if (ret)
                return ret;

        acc_size = ttm_bo_dma_acc_size(bdev, size, sizeof(*gbo));

        gbo->bo.bdev = bdev;
        drm_gem_vram_placement(gbo, TTM_PL_FLAG_VRAM | TTM_PL_FLAG_SYSTEM);

        ret = ttm_bo_init(bdev, &gbo->bo, size, ttm_bo_type_device,
                          &gbo->placement, pg_align, false, acc_size,
                          NULL, NULL, ttm_buffer_object_destroy);
        if (ret)
                goto err_drm_gem_object_release;

        return 0;

err_drm_gem_object_release:
        drm_gem_object_release(&gbo->bo.base);
        return ret;
}

/**
 * drm_gem_vram_create() - Creates a VRAM-backed GEM object
 * @dev:                the DRM device
 * @size:               the buffer size in bytes
 * @pg_align:           the buffer's alignment in multiples of the page size
 *
 * Returns:
 * A new instance of &struct drm_gem_vram_object on success, or
 * an ERR_PTR()-encoded error code otherwise.
 */
struct drm_gem_vram_object *drm_gem_vram_create(struct drm_device *dev,
                                                size_t size,
                                                unsigned long pg_align)
{
        struct drm_gem_vram_object *gbo;
        int ret;

        if (dev->driver->gem_create_object) {
                struct drm_gem_object *gem =
                        dev->driver->gem_create_object(dev, size);
                if (!gem)
                        return ERR_PTR(-ENOMEM);
                gbo = drm_gem_vram_of_gem(gem);
        } else {
                gbo = kzalloc(sizeof(*gbo), GFP_KERNEL);
                if (!gbo)
                        return ERR_PTR(-ENOMEM);
        }

        ret = drm_gem_vram_init(dev, gbo, size, pg_align);
        if (ret < 0)
                goto err_kfree;

        return gbo;

err_kfree:
        kfree(gbo);
        return ERR_PTR(ret);
}
EXPORT_SYMBOL(drm_gem_vram_create);

/**
 * drm_gem_vram_put() - Releases a reference to a VRAM-backed GEM object
 * @gbo:        the GEM VRAM object
 *
 * See ttm_bo_put() for more information.
 */
void drm_gem_vram_put(struct drm_gem_vram_object *gbo)
{
        ttm_bo_put(&gbo->bo);
}
EXPORT_SYMBOL(drm_gem_vram_put);

/**
 * drm_gem_vram_mmap_offset() - Returns a GEM VRAM object's mmap offset
 * @gbo:        the GEM VRAM object
 *
 * See drm_vma_node_offset_addr() for more information.
 *
 * Returns:
 * The buffer object's offset for userspace mappings on success, or
 * 0 if no offset is allocated.
 */
u64 drm_gem_vram_mmap_offset(struct drm_gem_vram_object *gbo)
{
        return drm_vma_node_offset_addr(&gbo->bo.base.vma_node);
}
EXPORT_SYMBOL(drm_gem_vram_mmap_offset);

static u64 drm_gem_vram_pg_offset(struct drm_gem_vram_object *gbo)
{
        /* Keep TTM behavior for now, remove when drivers are audited */
        if (WARN_ON_ONCE(!gbo->bo.mem.mm_node))
                return 0;

        return gbo->bo.mem.start;
}

/**
 * drm_gem_vram_offset() - \
        Returns a GEM VRAM object's offset in video memory
 * @gbo:        the GEM VRAM object
 *
 * This function returns the buffer object's offset in the device's video
 * memory. The buffer object has to be pinned to %TTM_PL_VRAM.
 *
 * Returns:
 * The buffer object's offset in video memory on success, or
 * a negative errno code otherwise.
 */
s64 drm_gem_vram_offset(struct drm_gem_vram_object *gbo)
{
        if (WARN_ON_ONCE(!gbo->pin_count))
                return (s64)-ENODEV;
        return drm_gem_vram_pg_offset(gbo) << PAGE_SHIFT;
}
EXPORT_SYMBOL(drm_gem_vram_offset);

static int drm_gem_vram_pin_locked(struct drm_gem_vram_object *gbo,
                                   unsigned long pl_flag)
{
        int i, ret;
        struct ttm_operation_ctx ctx = { false, false };

        if (gbo->pin_count)
                goto out;

        if (pl_flag)
                drm_gem_vram_placement(gbo, pl_flag);

        for (i = 0; i < gbo->placement.num_placement; ++i)
                gbo->placements[i].flags |= TTM_PL_FLAG_NO_EVICT;

        ret = ttm_bo_validate(&gbo->bo, &gbo->placement, &ctx);
        if (ret < 0)
                return ret;

out:
        ++gbo->pin_count;

        return 0;
}

/**
 * drm_gem_vram_pin() - Pins a GEM VRAM object in a region.
 * @gbo:        the GEM VRAM object
 * @pl_flag:    a bitmask of possible memory regions
 *
 * Pinning a buffer object ensures that it is not evicted from
 * a memory region. A pinned buffer object has to be unpinned before
 * it can be pinned to another region. If the pl_flag argument is 0,
 * the buffer is pinned at its current location (video RAM or system
 * memory).
 *
 * Small buffer objects, such as cursor images, can lead to memory
 * fragmentation if they are pinned in the middle of video RAM. This
 * is especially a problem on devices with only a small amount of
 * video RAM. Fragmentation can prevent the primary framebuffer from
 * fitting in, even though there's enough memory overall. The modifier
 * DRM_GEM_VRAM_PL_FLAG_TOPDOWN marks the buffer object to be pinned
 * at the high end of the memory region to avoid fragmentation.
 *
 * Returns:
 * 0 on success, or
 * a negative error code otherwise.
 */
int drm_gem_vram_pin(struct drm_gem_vram_object *gbo, unsigned long pl_flag)
{
        int ret;

        ret = ttm_bo_reserve(&gbo->bo, true, false, NULL);
        if (ret)
                return ret;
        ret = drm_gem_vram_pin_locked(gbo, pl_flag);
        ttm_bo_unreserve(&gbo->bo);

        return ret;
}
EXPORT_SYMBOL(drm_gem_vram_pin);

static int drm_gem_vram_unpin_locked(struct drm_gem_vram_object *gbo)
{
        int i, ret;
        struct ttm_operation_ctx ctx = { false, false };

        if (WARN_ON_ONCE(!gbo->pin_count))
                return 0;

        --gbo->pin_count;
        if (gbo->pin_count)
                return 0;

        for (i = 0; i < gbo->placement.num_placement ; ++i)
                gbo->placements[i].flags &= ~TTM_PL_FLAG_NO_EVICT;

        ret = ttm_bo_validate(&gbo->bo, &gbo->placement, &ctx);
        if (ret < 0)
                return ret;

        return 0;
}

/**
 * drm_gem_vram_unpin() - Unpins a GEM VRAM object
 * @gbo:        the GEM VRAM object
 *
 * Returns:
 * 0 on success, or
 * a negative error code otherwise.
 */
int drm_gem_vram_unpin(struct drm_gem_vram_object *gbo)
{
        int ret;

        ret = ttm_bo_reserve(&gbo->bo, true, false, NULL);
        if (ret)
                return ret;
        ret = drm_gem_vram_unpin_locked(gbo);
        ttm_bo_unreserve(&gbo->bo);

        return ret;
}
EXPORT_SYMBOL(drm_gem_vram_unpin);

static void *drm_gem_vram_kmap_locked(struct drm_gem_vram_object *gbo,
                                      bool map, bool *is_iomem)
{
        int ret;
        struct ttm_bo_kmap_obj *kmap = &gbo->kmap;

        if (gbo->kmap_use_count > 0)
                goto out;

        if (kmap->virtual || !map)
                goto out;

        ret = ttm_bo_kmap(&gbo->bo, 0, gbo->bo.num_pages, kmap);
        if (ret)
                return ERR_PTR(ret);

out:
        if (!kmap->virtual) {
                if (is_iomem)
                        *is_iomem = false;
                return NULL; /* not mapped; don't increment ref */
        }
        ++gbo->kmap_use_count;
        if (is_iomem)
                return ttm_kmap_obj_virtual(kmap, is_iomem);
        return kmap->virtual;
}

/**
 * drm_gem_vram_kmap() - Maps a GEM VRAM object into kernel address space
 * @gbo:        the GEM VRAM object
 * @map:        establish a mapping if necessary
 * @is_iomem:   returns true if the mapped memory is I/O memory, or false \
        otherwise; can be NULL
 *
 * This function maps the buffer object into the kernel's address space
 * or returns the current mapping. If the parameter map is false, the
 * function only queries the current mapping, but does not establish a
 * new one.
 *
 * Returns:
 * The buffers virtual address if mapped, or
 * NULL if not mapped, or
 * an ERR_PTR()-encoded error code otherwise.
 */
void *drm_gem_vram_kmap(struct drm_gem_vram_object *gbo, bool map,
                        bool *is_iomem)
{
        int ret;
        void *virtual;

        ret = ttm_bo_reserve(&gbo->bo, true, false, NULL);
        if (ret)
                return ERR_PTR(ret);
        virtual = drm_gem_vram_kmap_locked(gbo, map, is_iomem);
        ttm_bo_unreserve(&gbo->bo);

        return virtual;
}
EXPORT_SYMBOL(drm_gem_vram_kmap);

static void drm_gem_vram_kunmap_locked(struct drm_gem_vram_object *gbo)
{
        if (WARN_ON_ONCE(!gbo->kmap_use_count))
                return;
        if (--gbo->kmap_use_count > 0)
                return;

        /*
         * Permanently mapping and unmapping buffers adds overhead from
         * updating the page tables and creates debugging output. Therefore,
         * we delay the actual unmap operation until the BO gets evicted
         * from memory. See drm_gem_vram_bo_driver_move_notify().
         */
}

/**
 * drm_gem_vram_kunmap() - Unmaps a GEM VRAM object
 * @gbo:        the GEM VRAM object
 */
void drm_gem_vram_kunmap(struct drm_gem_vram_object *gbo)
{
        int ret;

        ret = ttm_bo_reserve(&gbo->bo, false, false, NULL);
        if (WARN_ONCE(ret, "ttm_bo_reserve_failed(): ret=%d\n", ret))
                return;
        drm_gem_vram_kunmap_locked(gbo);
        ttm_bo_unreserve(&gbo->bo);
}
EXPORT_SYMBOL(drm_gem_vram_kunmap);

/**
 * drm_gem_vram_vmap() - Pins and maps a GEM VRAM object into kernel address
 *                       space
 * @gbo:        The GEM VRAM object to map
 *
 * The vmap function pins a GEM VRAM object to its current location, either
 * system or video memory, and maps its buffer into kernel address space.
 * As pinned object cannot be relocated, you should avoid pinning objects
 * permanently. Call drm_gem_vram_vunmap() with the returned address to
 * unmap and unpin the GEM VRAM object.
 *
 * If you have special requirements for the pinning or mapping operations,
 * call drm_gem_vram_pin() and drm_gem_vram_kmap() directly.
 *
 * Returns:
 * The buffer's virtual address on success, or
 * an ERR_PTR()-encoded error code otherwise.
 */
void *drm_gem_vram_vmap(struct drm_gem_vram_object *gbo)
{
        int ret;
        void *base;

        ret = ttm_bo_reserve(&gbo->bo, true, false, NULL);
        if (ret)
                return ERR_PTR(ret);

        ret = drm_gem_vram_pin_locked(gbo, 0);
        if (ret)
                goto err_ttm_bo_unreserve;
        base = drm_gem_vram_kmap_locked(gbo, true, NULL);
        if (IS_ERR(base)) {
                ret = PTR_ERR(base);
                goto err_drm_gem_vram_unpin_locked;
        }

        ttm_bo_unreserve(&gbo->bo);

        return base;

err_drm_gem_vram_unpin_locked:
        drm_gem_vram_unpin_locked(gbo);
err_ttm_bo_unreserve:
        ttm_bo_unreserve(&gbo->bo);
        return ERR_PTR(ret);
}
EXPORT_SYMBOL(drm_gem_vram_vmap);

/**
 * drm_gem_vram_vunmap() - Unmaps and unpins a GEM VRAM object
 * @gbo:        The GEM VRAM object to unmap
 * @vaddr:      The mapping's base address as returned by drm_gem_vram_vmap()
 *
 * A call to drm_gem_vram_vunmap() unmaps and unpins a GEM VRAM buffer. See
 * the documentation for drm_gem_vram_vmap() for more information.
 */
void drm_gem_vram_vunmap(struct drm_gem_vram_object *gbo, void *vaddr)
{
        int ret;

        ret = ttm_bo_reserve(&gbo->bo, false, false, NULL);
        if (WARN_ONCE(ret, "ttm_bo_reserve_failed(): ret=%d\n", ret))
                return;

        drm_gem_vram_kunmap_locked(gbo);
        drm_gem_vram_unpin_locked(gbo);

        ttm_bo_unreserve(&gbo->bo);
}
EXPORT_SYMBOL(drm_gem_vram_vunmap);

/**
 * drm_gem_vram_fill_create_dumb() - \
        Helper for implementing &struct drm_driver.dumb_create
 * @file:               the DRM file
 * @dev:                the DRM device
 * @pg_align:           the buffer's alignment in multiples of the page size
 * @pitch_align:        the scanline's alignment in powers of 2
 * @args:               the arguments as provided to \
                                &struct drm_driver.dumb_create
 *
 * This helper function fills &struct drm_mode_create_dumb, which is used
 * by &struct drm_driver.dumb_create. Implementations of this interface
 * should forwards their arguments to this helper, plus the driver-specific
 * parameters.
 *
 * Returns:
 * 0 on success, or
 * a negative error code otherwise.
 */
int drm_gem_vram_fill_create_dumb(struct drm_file *file,
                                  struct drm_device *dev,
                                  unsigned long pg_align,
                                  unsigned long pitch_align,
                                  struct drm_mode_create_dumb *args)
{
        size_t pitch, size;
        struct drm_gem_vram_object *gbo;
        int ret;
        u32 handle;

        pitch = args->width * DIV_ROUND_UP(args->bpp, 8);
        if (pitch_align) {
                if (WARN_ON_ONCE(!is_power_of_2(pitch_align)))
                        return -EINVAL;
                pitch = ALIGN(pitch, pitch_align);
        }
        size = pitch * args->height;

        size = roundup(size, PAGE_SIZE);
        if (!size)
                return -EINVAL;

        gbo = drm_gem_vram_create(dev, size, pg_align);
        if (IS_ERR(gbo))
                return PTR_ERR(gbo);

        ret = drm_gem_handle_create(file, &gbo->bo.base, &handle);
        if (ret)
                goto err_drm_gem_object_put;

        drm_gem_object_put(&gbo->bo.base);

        args->pitch = pitch;
        args->size = size;
        args->handle = handle;

        return 0;

err_drm_gem_object_put:
        drm_gem_object_put(&gbo->bo.base);
        return ret;
}
EXPORT_SYMBOL(drm_gem_vram_fill_create_dumb);

/*
 * Helpers for struct ttm_bo_driver
 */

static bool drm_is_gem_vram(struct ttm_buffer_object *bo)
{
        return (bo->destroy == ttm_buffer_object_destroy);
}

static void drm_gem_vram_bo_driver_evict_flags(struct drm_gem_vram_object *gbo,
                                               struct ttm_placement *pl)
{
        drm_gem_vram_placement(gbo, TTM_PL_FLAG_SYSTEM);
        *pl = gbo->placement;
}

static void drm_gem_vram_bo_driver_move_notify(struct drm_gem_vram_object *gbo,
                                               bool evict,
                                               struct ttm_mem_reg *new_mem)
{
        struct ttm_bo_kmap_obj *kmap = &gbo->kmap;

        if (WARN_ON_ONCE(gbo->kmap_use_count))
                return;

        if (!kmap->virtual)
                return;
        ttm_bo_kunmap(kmap);
        kmap->virtual = NULL;
}

/*
 * Helpers for struct drm_gem_object_funcs
 */

/**
 * drm_gem_vram_object_free() - \
        Implements &struct drm_gem_object_funcs.free
 * @gem:       GEM object. Refers to &struct drm_gem_vram_object.gem
 */
static void drm_gem_vram_object_free(struct drm_gem_object *gem)
{
        struct drm_gem_vram_object *gbo = drm_gem_vram_of_gem(gem);

        drm_gem_vram_put(gbo);
}

/*
 * Helpers for dump buffers
 */

/**
 * drm_gem_vram_driver_create_dumb() - \
        Implements &struct drm_driver.dumb_create
 * @file:               the DRM file
 * @dev:                the DRM device
 * @args:               the arguments as provided to \
                                &struct drm_driver.dumb_create
 *
 * This function requires the driver to use @drm_device.vram_mm for its
 * instance of VRAM MM.
 *
 * Returns:
 * 0 on success, or
 * a negative error code otherwise.
 */
int drm_gem_vram_driver_dumb_create(struct drm_file *file,
                                    struct drm_device *dev,
                                    struct drm_mode_create_dumb *args)
{
        if (WARN_ONCE(!dev->vram_mm, "VRAM MM not initialized"))
                return -EINVAL;

        return drm_gem_vram_fill_create_dumb(file, dev, 0, 0, args);
}
EXPORT_SYMBOL(drm_gem_vram_driver_dumb_create);

/**
 * drm_gem_vram_driver_dumb_mmap_offset() - \
        Implements &struct drm_driver.dumb_mmap_offset
 * @file:       DRM file pointer.
 * @dev:        DRM device.
 * @handle:     GEM handle
 * @offset:     Returns the mapping's memory offset on success
 *
 * Returns:
 * 0 on success, or
 * a negative errno code otherwise.
 */
int drm_gem_vram_driver_dumb_mmap_offset(struct drm_file *file,
                                         struct drm_device *dev,
                                         uint32_t handle, uint64_t *offset)
{
        struct drm_gem_object *gem;
        struct drm_gem_vram_object *gbo;

        gem = drm_gem_object_lookup(file, handle);
        if (!gem)
                return -ENOENT;

        gbo = drm_gem_vram_of_gem(gem);
        *offset = drm_gem_vram_mmap_offset(gbo);

        drm_gem_object_put(gem);

        return 0;
}
EXPORT_SYMBOL(drm_gem_vram_driver_dumb_mmap_offset);

/*
 * Helpers for struct drm_plane_helper_funcs
 */

/**
 * drm_gem_vram_plane_helper_prepare_fb() - \
 *      Implements &struct drm_plane_helper_funcs.prepare_fb
 * @plane:      a DRM plane
 * @new_state:  the plane's new state
 *
 * During plane updates, this function sets the plane's fence and
 * pins the GEM VRAM objects of the plane's new framebuffer to VRAM.
 * Call drm_gem_vram_plane_helper_cleanup_fb() to unpin them.
 *
 * Returns:
 *      0 on success, or
 *      a negative errno code otherwise.
 */
int
drm_gem_vram_plane_helper_prepare_fb(struct drm_plane *plane,
                                     struct drm_plane_state *new_state)
{
        size_t i;
        struct drm_gem_vram_object *gbo;
        int ret;

        if (!new_state->fb)
                return 0;

        for (i = 0; i < ARRAY_SIZE(new_state->fb->obj); ++i) {
                if (!new_state->fb->obj[i])
                        continue;
                gbo = drm_gem_vram_of_gem(new_state->fb->obj[i]);
                ret = drm_gem_vram_pin(gbo, DRM_GEM_VRAM_PL_FLAG_VRAM);
                if (ret)
                        goto err_drm_gem_vram_unpin;
        }

        ret = drm_gem_fb_prepare_fb(plane, new_state);
        if (ret)
                goto err_drm_gem_vram_unpin;

        return 0;

err_drm_gem_vram_unpin:
        while (i) {
                --i;
                gbo = drm_gem_vram_of_gem(new_state->fb->obj[i]);
                drm_gem_vram_unpin(gbo);
        }
        return ret;
}
EXPORT_SYMBOL(drm_gem_vram_plane_helper_prepare_fb);

/**
 * drm_gem_vram_plane_helper_cleanup_fb() - \
 *      Implements &struct drm_plane_helper_funcs.cleanup_fb
 * @plane:      a DRM plane
 * @old_state:  the plane's old state
 *
 * During plane updates, this function unpins the GEM VRAM
 * objects of the plane's old framebuffer from VRAM. Complements
 * drm_gem_vram_plane_helper_prepare_fb().
 */
void
drm_gem_vram_plane_helper_cleanup_fb(struct drm_plane *plane,
                                     struct drm_plane_state *old_state)
{
        size_t i;
        struct drm_gem_vram_object *gbo;

        if (!old_state->fb)
                return;

        for (i = 0; i < ARRAY_SIZE(old_state->fb->obj); ++i) {
                if (!old_state->fb->obj[i])
                        continue;
                gbo = drm_gem_vram_of_gem(old_state->fb->obj[i]);
                drm_gem_vram_unpin(gbo);
        }
}
EXPORT_SYMBOL(drm_gem_vram_plane_helper_cleanup_fb);

/*
 * Helpers for struct drm_simple_display_pipe_funcs
 */

/**
 * drm_gem_vram_simple_display_pipe_prepare_fb() - \
 *      Implements &struct drm_simple_display_pipe_funcs.prepare_fb
 * @pipe:       a simple display pipe
 * @new_state:  the plane's new state
 *
 * During plane updates, this function pins the GEM VRAM
 * objects of the plane's new framebuffer to VRAM. Call
 * drm_gem_vram_simple_display_pipe_cleanup_fb() to unpin them.
 *
 * Returns:
 *      0 on success, or
 *      a negative errno code otherwise.
 */
int drm_gem_vram_simple_display_pipe_prepare_fb(
        struct drm_simple_display_pipe *pipe,
        struct drm_plane_state *new_state)
{
        return drm_gem_vram_plane_helper_prepare_fb(&pipe->plane, new_state);
}
EXPORT_SYMBOL(drm_gem_vram_simple_display_pipe_prepare_fb);

/**
 * drm_gem_vram_simple_display_pipe_cleanup_fb() - \
 *      Implements &struct drm_simple_display_pipe_funcs.cleanup_fb
 * @pipe:       a simple display pipe
 * @old_state:  the plane's old state
 *
 * During plane updates, this function unpins the GEM VRAM
 * objects of the plane's old framebuffer from VRAM. Complements
 * drm_gem_vram_simple_display_pipe_prepare_fb().
 */
void drm_gem_vram_simple_display_pipe_cleanup_fb(
        struct drm_simple_display_pipe *pipe,
        struct drm_plane_state *old_state)
{
        drm_gem_vram_plane_helper_cleanup_fb(&pipe->plane, old_state);
}
EXPORT_SYMBOL(drm_gem_vram_simple_display_pipe_cleanup_fb);

/*
 * PRIME helpers
 */

/**
 * drm_gem_vram_object_pin() - \
        Implements &struct drm_gem_object_funcs.pin
 * @gem:        The GEM object to pin
 *
 * Returns:
 * 0 on success, or
 * a negative errno code otherwise.
 */
static int drm_gem_vram_object_pin(struct drm_gem_object *gem)
{
        struct drm_gem_vram_object *gbo = drm_gem_vram_of_gem(gem);

        /* Fbdev console emulation is the use case of these PRIME
         * helpers. This may involve updating a hardware buffer from
         * a shadow FB. We pin the buffer to it's current location
         * (either video RAM or system memory) to prevent it from
         * being relocated during the update operation. If you require
         * the buffer to be pinned to VRAM, implement a callback that
         * sets the flags accordingly.
         */
        return drm_gem_vram_pin(gbo, 0);
}

/**
 * drm_gem_vram_object_unpin() - \
        Implements &struct drm_gem_object_funcs.unpin
 * @gem:        The GEM object to unpin
 */
static void drm_gem_vram_object_unpin(struct drm_gem_object *gem)
{
        struct drm_gem_vram_object *gbo = drm_gem_vram_of_gem(gem);

        drm_gem_vram_unpin(gbo);
}

/**
 * drm_gem_vram_object_vmap() - \
        Implements &struct drm_gem_object_funcs.vmap
 * @gem:        The GEM object to map
 *
 * Returns:
 * The buffers virtual address on success, or
 * NULL otherwise.
 */
static void *drm_gem_vram_object_vmap(struct drm_gem_object *gem)
{
        struct drm_gem_vram_object *gbo = drm_gem_vram_of_gem(gem);
        void *base;

        base = drm_gem_vram_vmap(gbo);
        if (IS_ERR(base))
                return NULL;
        return base;
}

/**
 * drm_gem_vram_object_vunmap() - \
        Implements &struct drm_gem_object_funcs.vunmap
 * @gem:        The GEM object to unmap
 * @vaddr:      The mapping's base address
 */
static void drm_gem_vram_object_vunmap(struct drm_gem_object *gem,
                                       void *vaddr)
{
        struct drm_gem_vram_object *gbo = drm_gem_vram_of_gem(gem);

        drm_gem_vram_vunmap(gbo, vaddr);
}

/*
 * GEM object funcs
 */

static const struct drm_gem_object_funcs drm_gem_vram_object_funcs = {
        .free   = drm_gem_vram_object_free,
        .pin    = drm_gem_vram_object_pin,
        .unpin  = drm_gem_vram_object_unpin,
        .vmap   = drm_gem_vram_object_vmap,
        .vunmap = drm_gem_vram_object_vunmap,
        .mmap   = drm_gem_ttm_mmap,
        .print_info = drm_gem_ttm_print_info,
};

/*
 * VRAM memory manager
 */

/*
 * TTM TT
 */

static void backend_func_destroy(struct ttm_tt *tt)
{
        ttm_tt_fini(tt);
        kfree(tt);
}

static struct ttm_backend_func backend_func = {
        .destroy = backend_func_destroy
};

/*
 * TTM BO device
 */

static struct ttm_tt *bo_driver_ttm_tt_create(struct ttm_buffer_object *bo,
                                              uint32_t page_flags)
{
        struct ttm_tt *tt;
        int ret;

        tt = kzalloc(sizeof(*tt), GFP_KERNEL);
        if (!tt)
                return NULL;

        tt->func = &backend_func;

        ret = ttm_tt_init(tt, bo, page_flags);
        if (ret < 0)
                goto err_ttm_tt_init;

        return tt;

err_ttm_tt_init:
        kfree(tt);
        return NULL;
}

static int bo_driver_init_mem_type(struct ttm_bo_device *bdev, uint32_t type,
                                   struct ttm_mem_type_manager *man)
{
        switch (type) {
        case TTM_PL_SYSTEM:
                man->flags = 0;
                man->available_caching = TTM_PL_MASK_CACHING;
                man->default_caching = TTM_PL_FLAG_CACHED;
                break;
        case TTM_PL_VRAM:
                man->func = &ttm_bo_manager_func;
                man->flags = TTM_MEMTYPE_FLAG_FIXED;
                man->available_caching = TTM_PL_FLAG_UNCACHED |
                                         TTM_PL_FLAG_WC;
                man->default_caching = TTM_PL_FLAG_WC;
                break;
        default:
                return -EINVAL;
        }
        return 0;
}

static void bo_driver_evict_flags(struct ttm_buffer_object *bo,
                                  struct ttm_placement *placement)
{
        struct drm_gem_vram_object *gbo;

        /* TTM may pass BOs that are not GEM VRAM BOs. */
        if (!drm_is_gem_vram(bo))
                return;

        gbo = drm_gem_vram_of_bo(bo);

        drm_gem_vram_bo_driver_evict_flags(gbo, placement);
}

static void bo_driver_move_notify(struct ttm_buffer_object *bo,
                                  bool evict,
                                  struct ttm_mem_reg *new_mem)
{
        struct drm_gem_vram_object *gbo;

        /* TTM may pass BOs that are not GEM VRAM BOs. */
        if (!drm_is_gem_vram(bo))
                return;

        gbo = drm_gem_vram_of_bo(bo);

        drm_gem_vram_bo_driver_move_notify(gbo, evict, new_mem);
}

static int bo_driver_io_mem_reserve(struct ttm_bo_device *bdev,
                                    struct ttm_mem_reg *mem)
{
        struct drm_vram_mm *vmm = drm_vram_mm_of_bdev(bdev);

        mem->bus.addr = NULL;
        mem->bus.size = mem->num_pages << PAGE_SHIFT;

        switch (mem->mem_type) {
        case TTM_PL_SYSTEM:     /* nothing to do */
                mem->bus.offset = 0;
                mem->bus.base = 0;
                mem->bus.is_iomem = false;
                break;
        case TTM_PL_VRAM:
                mem->bus.offset = mem->start << PAGE_SHIFT;
                mem->bus.base = vmm->vram_base;
                mem->bus.is_iomem = true;
                break;
        default:
                return -EINVAL;
        }

        return 0;
}

static struct ttm_bo_driver bo_driver = {
        .ttm_tt_create = bo_driver_ttm_tt_create,
        .ttm_tt_populate = ttm_pool_populate,
        .ttm_tt_unpopulate = ttm_pool_unpopulate,
        .init_mem_type = bo_driver_init_mem_type,
        .eviction_valuable = ttm_bo_eviction_valuable,
        .evict_flags = bo_driver_evict_flags,
        .move_notify = bo_driver_move_notify,
        .io_mem_reserve = bo_driver_io_mem_reserve,
};

/*
 * struct drm_vram_mm
 */

static int drm_vram_mm_debugfs(struct seq_file *m, void *data)
{
        struct drm_info_node *node = (struct drm_info_node *) m->private;
        struct drm_vram_mm *vmm = node->minor->dev->vram_mm;
        struct drm_mm *mm = vmm->bdev.man[TTM_PL_VRAM].priv;
        struct drm_printer p = drm_seq_file_printer(m);

        spin_lock(&ttm_bo_glob.lru_lock);
        drm_mm_print(mm, &p);
        spin_unlock(&ttm_bo_glob.lru_lock);
        return 0;
}

static const struct drm_info_list drm_vram_mm_debugfs_list[] = {
        { "vram-mm", drm_vram_mm_debugfs, 0, NULL },
};

/**
 * drm_vram_mm_debugfs_init() - Register VRAM MM debugfs file.
 *
 * @minor: drm minor device.
 *
 */
void drm_vram_mm_debugfs_init(struct drm_minor *minor)
{
        drm_debugfs_create_files(drm_vram_mm_debugfs_list,
                                 ARRAY_SIZE(drm_vram_mm_debugfs_list),
                                 minor->debugfs_root, minor);
}
EXPORT_SYMBOL(drm_vram_mm_debugfs_init);

static int drm_vram_mm_init(struct drm_vram_mm *vmm, struct drm_device *dev,
                            uint64_t vram_base, size_t vram_size)
{
        int ret;

        vmm->vram_base = vram_base;
        vmm->vram_size = vram_size;

        ret = ttm_bo_device_init(&vmm->bdev, &bo_driver,
                                 dev->anon_inode->i_mapping,
                                 dev->vma_offset_manager,
                                 true);
        if (ret)
                return ret;

        ret = ttm_bo_init_mm(&vmm->bdev, TTM_PL_VRAM, vram_size >> PAGE_SHIFT);
        if (ret)
                return ret;

        return 0;
}

static void drm_vram_mm_cleanup(struct drm_vram_mm *vmm)
{
        ttm_bo_device_release(&vmm->bdev);
}

/*
 * Helpers for integration with struct drm_device
 */

/* deprecated; use drmm_vram_mm_init() */
struct drm_vram_mm *drm_vram_helper_alloc_mm(
        struct drm_device *dev, uint64_t vram_base, size_t vram_size)
{
        int ret;

        if (WARN_ON(dev->vram_mm))
                return dev->vram_mm;

        dev->vram_mm = kzalloc(sizeof(*dev->vram_mm), GFP_KERNEL);
        if (!dev->vram_mm)
                return ERR_PTR(-ENOMEM);

        ret = drm_vram_mm_init(dev->vram_mm, dev, vram_base, vram_size);
        if (ret)
                goto err_kfree;

        return dev->vram_mm;

err_kfree:
        kfree(dev->vram_mm);
        dev->vram_mm = NULL;
        return ERR_PTR(ret);
}
EXPORT_SYMBOL(drm_vram_helper_alloc_mm);

void drm_vram_helper_release_mm(struct drm_device *dev)
{
        if (!dev->vram_mm)
                return;

        drm_vram_mm_cleanup(dev->vram_mm);
        kfree(dev->vram_mm);
        dev->vram_mm = NULL;
}
EXPORT_SYMBOL(drm_vram_helper_release_mm);

static void drm_vram_mm_release(struct drm_device *dev, void *ptr)
{
        drm_vram_helper_release_mm(dev);
}

/**
 * drmm_vram_helper_init - Initializes a device's instance of
 *                         &struct drm_vram_mm
 * @dev:        the DRM device
 * @vram_base:  the base address of the video memory
 * @vram_size:  the size of the video memory in bytes
 *
 * Creates a new instance of &struct drm_vram_mm and stores it in
 * struct &drm_device.vram_mm. The instance is auto-managed and cleaned
 * up as part of device cleanup. Calling this function multiple times
 * will generate an error message.
 *
 * Returns:
 * 0 on success, or a negative errno code otherwise.
 */
int drmm_vram_helper_init(struct drm_device *dev, uint64_t vram_base,
                          size_t vram_size)
{
        struct drm_vram_mm *vram_mm;

        if (drm_WARN_ON_ONCE(dev, dev->vram_mm))
                return 0;

        vram_mm = drm_vram_helper_alloc_mm(dev, vram_base, vram_size);
        if (IS_ERR(vram_mm))
                return PTR_ERR(vram_mm);
        return drmm_add_action_or_reset(dev, drm_vram_mm_release, NULL);
}
EXPORT_SYMBOL(drmm_vram_helper_init);

/*
 * Mode-config helpers
 */

static enum drm_mode_status
drm_vram_helper_mode_valid_internal(struct drm_device *dev,
                                    const struct drm_display_mode *mode,
                                    unsigned long max_bpp)
{
        struct drm_vram_mm *vmm = dev->vram_mm;
        unsigned long fbsize, fbpages, max_fbpages;

        if (WARN_ON(!dev->vram_mm))
                return MODE_BAD;

        max_fbpages = (vmm->vram_size / 2) >> PAGE_SHIFT;

        fbsize = mode->hdisplay * mode->vdisplay * max_bpp;
        fbpages = DIV_ROUND_UP(fbsize, PAGE_SIZE);

        if (fbpages > max_fbpages)
                return MODE_MEM;

        return MODE_OK;
}

/**
 * drm_vram_helper_mode_valid - Tests if a display mode's
 *      framebuffer fits into the available video memory.
 * @dev:        the DRM device
 * @mode:       the mode to test
 *
 * This function tests if enough video memory is available for using the
 * specified display mode. Atomic modesetting requires importing the
 * designated framebuffer into video memory before evicting the active
 * one. Hence, any framebuffer may consume at most half of the available
 * VRAM. Display modes that require a larger framebuffer can not be used,
 * even if the CRTC does support them. Each framebuffer is assumed to
 * have 32-bit color depth.
 *
 * Note:
 * The function can only test if the display mode is supported in
 * general. If there are too many framebuffers pinned to video memory,
 * a display mode may still not be usable in practice. The color depth of
 * 32-bit fits all current use case. A more flexible test can be added
 * when necessary.
 *
 * Returns:
 * MODE_OK if the display mode is supported, or an error code of type
 * enum drm_mode_status otherwise.
 */
enum drm_mode_status
drm_vram_helper_mode_valid(struct drm_device *dev,
                           const struct drm_display_mode *mode)
{
        static const unsigned long max_bpp = 4; /* DRM_FORMAT_XRGB8888 */

        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");