path: root/drivers/gpu/drm/omapdrm/omap_gem.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (C) 2011 Texas Instruments Incorporated - https://www.ti.com/
 * Author: Rob Clark <rob.clark@linaro.org>
 */

#include <linux/dma-mapping.h>
#include <linux/seq_file.h>
#include <linux/shmem_fs.h>
#include <linux/spinlock.h>
#include <linux/pfn_t.h>

#include <drm/drm_prime.h>
#include <drm/drm_vma_manager.h>

#include "omap_drv.h"
#include "omap_dmm_tiler.h"

/*
 * GEM buffer object implementation.
 */

/* note: we use upper 8 bits of flags for driver-internal flags: */
#define OMAP_BO_MEM_DMA_API	0x01000000	/* memory allocated with the dma_alloc_* API */
#define OMAP_BO_MEM_SHMEM	0x02000000	/* memory allocated through shmem backing */
#define OMAP_BO_MEM_DMABUF	0x08000000	/* memory imported from a dmabuf */

struct omap_gem_object {
	struct drm_gem_object base;

	struct list_head mm_list;

	u32 flags;

	/** width/height for tiled formats (rounded up to slot boundaries) */
	u16 width, height;

	/** roll applied when mapping to DMM */
	u32 roll;

	/** protects pin_cnt, block, pages, dma_addrs and vaddr */
	struct mutex lock;

	/**
	 * dma_addr contains the buffer DMA address. It is valid for
	 *
	 * - buffers allocated through the DMA mapping API (with the
	 *   OMAP_BO_MEM_DMA_API flag set)
	 *
	 * - buffers imported from dmabuf (with the OMAP_BO_MEM_DMABUF flag set)
	 *   if they are physically contiguous (when sgt->orig_nents == 1)
	 *
	 * - buffers mapped through the TILER when pin_cnt is not zero, in which
	 *   case the DMA address points to the TILER aperture
	 *
	 * Physically contiguous buffers have their DMA address equal to the
	 * physical address as we don't remap those buffers through the TILER.
	 *
	 * Buffers mapped to the TILER have their DMA address pointing to the
	 * TILER aperture. As TILER mappings are refcounted (through pin_cnt)
	 * the DMA address must be accessed through omap_gem_pin() to ensure
	 * that the mapping won't disappear unexpectedly. References must be
	 * released with omap_gem_unpin().
	 */
	dma_addr_t dma_addr;

	/**
	 * # of users
	 */
	refcount_t pin_cnt;

	/**
	 * If the buffer has been imported from a dmabuf the OMAP_DB_DMABUF flag
	 * is set and the sgt field is valid.
	 */
	struct sg_table *sgt;

	/**
	 * tiler block used when buffer is remapped in DMM/TILER.
	 */
	struct tiler_block *block;

	/**
	 * Array of backing pages, if allocated.  Note that pages are never
	 * allocated for buffers originally allocated from contiguous memory
	 */
	struct page **pages;

	/** addresses corresponding to pages in above array */
	dma_addr_t *dma_addrs;

	/**
	 * Virtual address, if mapped.
	 */
	void *vaddr;
};

#define to_omap_bo(x) container_of(x, struct omap_gem_object, base)

/* To deal with userspace mmap'ings of 2d tiled buffers, which (a) are
 * not necessarily pinned in TILER all the time, and (b) when they are
 * they are not necessarily page aligned, we reserve one or more small
 * regions in each of the 2d containers to use as a user-GART where we
 * can create a second page-aligned mapping of parts of the buffer
 * being accessed from userspace.
 *
 * Note that we could optimize slightly when we know that multiple
 * tiler containers are backed by the same PAT.. but I'll leave that
 * for later..
 */
#define NUM_USERGART_ENTRIES 2
struct omap_drm_usergart_entry {
	struct tiler_block *block;	/* the reserved tiler block */
	dma_addr_t dma_addr;
	struct drm_gem_object *obj;	/* the current pinned obj */
	pgoff_t obj_pgoff;		/* page offset of obj currently
					   mapped in */
};

struct omap_drm_usergart {
	struct omap_drm_usergart_entry entry[NUM_USERGART_ENTRIES];
	int height;				/* height in rows */
	int height_shift;		/* ilog2(height in rows) */
	int slot_shift;			/* ilog2(width per slot) */
	int stride_pfn;			/* stride in pages */
	int last;				/* index of last used entry */
};

/* -----------------------------------------------------------------------------
 * Helpers
 */

/** get mmap offset */
u64 omap_gem_mmap_offset(struct drm_gem_object *obj)
{
	struct drm_device *dev = obj->dev;
	int ret;
	size_t size;

	/* Make it mmapable */
	size = omap_gem_mmap_size(obj);
	ret = drm_gem_create_mmap_offset_size(obj, size);
	if (ret) {
		dev_err(dev->dev, "could not allocate mmap offset\n");
		return 0;
	}

	return drm_vma_node_offset_addr(&obj->vma_node);
}

static bool omap_gem_is_contiguous(struct omap_gem_object *omap_obj)
{
	if (omap_obj->flags & OMAP_BO_MEM_DMA_API)
		return true;

	if ((omap_obj->flags & OMAP_BO_MEM_DMABUF) && omap_obj->sgt->nents == 1)
		return true;

	return false;
}

/* -----------------------------------------------------------------------------
 * Eviction
 */

static void omap_gem_evict_entry(struct drm_gem_object *obj,
		enum tiler_fmt fmt, struct omap_drm_usergart_entry *entry)
{
	struct omap_gem_object *omap_obj = to_omap_bo(obj);
	struct omap_drm_private *priv = obj->dev->dev_private;
	int n = priv->usergart[fmt].height;
	size_t size = PAGE_SIZE * n;
	loff_t off = omap_gem_mmap_offset(obj) +
			(entry->obj_pgoff << PAGE_SHIFT);
	const int m = DIV_ROUND_UP(omap_obj->width << fmt, PAGE_SIZE);

	if (m > 1) {
		int i;
		/* if stride > than PAGE_SIZE then sparse mapping: */
		for (i = n; i > 0; i--) {
			unmap_mapping_range(obj->dev->anon_inode->i_mapping,
					    off, PAGE_SIZE, 1);
			off += PAGE_SIZE * m;
		}
	} else {
		unmap_mapping_range(obj->dev->anon_inode->i_mapping,
				    off, size, 1);
	}

	entry->obj = NULL;
}

/* Evict a buffer from usergart, if it is mapped there */
static void omap_gem_evict(struct drm_gem_object *obj)
{
	struct omap_gem_object *omap_obj = to_omap_bo(obj);
	struct omap_drm_private *priv = obj->dev->dev_private;

	if (omap_obj->flags & OMAP_BO_TILED_MASK) {
		enum tiler_fmt fmt = gem2fmt(omap_obj->flags);
		int i;

		for (i = 0; i < NUM_USERGART_ENTRIES; i++) {
			struct omap_drm_usergart_entry *entry =
				&priv->usergart[fmt].entry[i];

			if (entry->obj == obj)
				omap_gem_evict_entry(obj, fmt, entry);
		}
	}
}

/* -----------------------------------------------------------------------------
 * Page Management
 */

/*
 * Ensure backing pages are allocated. Must be called with the omap_obj.lock
 * held.
 */
static int omap_gem_attach_pages(struct drm_gem_object *obj)
{
	struct drm_device *dev = obj->dev;
	struct omap_gem_object *omap_obj = to_omap_bo(obj);
	struct page **pages;
	int npages = obj->size >> PAGE_SHIFT;
	int i, ret;
	dma_addr_t *addrs;

	lockdep_assert_held(&omap_obj->lock);

	/*
	 * If not using shmem (in which case backing pages don't need to be
	 * allocated) or if pages are already allocated we're done.
	 */
	if (!(omap_obj->flags & OMAP_BO_MEM_SHMEM) || omap_obj->pages)
		return 0;

	pages = drm_gem_get_pages(obj);
	if (IS_ERR(pages)) {
		dev_err(obj->dev->dev, "could not get pages: %ld\n", PTR_ERR