drivers/gpu/drm/i915/i915_mm.c

Source file repositories/reference/linux-study-clean/drivers/gpu/drm/i915/i915_mm.c

File Facts

System
Linux kernel
Corpus path
drivers/gpu/drm/i915/i915_mm.c
Extension
.c
Size
4728 bytes
Lines
165
Domain
Driver Families
Bucket
drivers/gpu
Inferred role
Driver Families: implementation source
Status
source implementation candidate

Why This File Exists

Repeatable hardware-adapter layer. Deep compatibility for every driver is out of scope; this atlas records patterns, probe lifecycles, bus glue, IRQ/DMA usage, and links back to core abstractions.

Dependency Surface

Detected Declarations

Annotated Snippet

struct remap_pfn {
	struct mm_struct *mm;
	unsigned long pfn;
	pgprot_t prot;

	struct sgt_iter sgt;
	resource_size_t iobase;
};

#define use_dma(io) ((io) != -1)

static inline unsigned long sgt_pfn(const struct remap_pfn *r)
{
	if (use_dma(r->iobase))
		return (r->sgt.dma + r->sgt.curr + r->iobase) >> PAGE_SHIFT;
	else
		return r->sgt.pfn + (r->sgt.curr >> PAGE_SHIFT);
}

static int remap_sg(pte_t *pte, unsigned long addr, void *data)
{
	struct remap_pfn *r = data;

	if (GEM_WARN_ON(!r->sgt.sgp))
		return -EINVAL;

	/* Special PTE are not associated with any struct page */
	set_pte_at(r->mm, addr, pte,
		   pte_mkspecial(pfn_pte(sgt_pfn(r), r->prot)));
	r->pfn++; /* track insertions in case we need to unwind later */

	r->sgt.curr += PAGE_SIZE;
	if (r->sgt.curr >= r->sgt.max)
		r->sgt = __sgt_iter(__sg_next(r->sgt.sgp), use_dma(r->iobase));

	return 0;
}

#define EXPECTED_FLAGS (VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP)

#if IS_ENABLED(CONFIG_X86)
static int remap_pfn(pte_t *pte, unsigned long addr, void *data)
{
	struct remap_pfn *r = data;

	/* Special PTE are not associated with any struct page */
	set_pte_at(r->mm, addr, pte, pte_mkspecial(pfn_pte(r->pfn, r->prot)));
	r->pfn++;

	return 0;
}

/**
 * remap_io_mapping - remap an IO mapping to userspace
 * @vma: user vma to map to
 * @addr: target user address to start at
 * @pfn: physical address of kernel memory
 * @size: size of map area
 * @iomap: the source io_mapping
 *
 *  Note: this is only safe if the mm semaphore is held when called.
 */
int remap_io_mapping(struct vm_area_struct *vma,
		     unsigned long addr, unsigned long pfn, unsigned long size,
		     struct io_mapping *iomap)
{
	struct remap_pfn r;
	int err;

	GEM_BUG_ON((vma->vm_flags & EXPECTED_FLAGS) != EXPECTED_FLAGS);

	/* We rely on prevalidation of the io-mapping to skip pfnmap tracking. */
	r.mm = vma->vm_mm;
	r.pfn = pfn;
	r.prot = __pgprot((pgprot_val(iomap->prot) & _PAGE_CACHE_MASK) |
			  (pgprot_val(vma->vm_page_prot) & ~_PAGE_CACHE_MASK));

	err = apply_to_page_range(r.mm, addr, size, remap_pfn, &r);
	if (unlikely(err)) {
		zap_special_vma_range(vma, addr, (r.pfn - pfn) << PAGE_SHIFT);
		return err;
	}

	return 0;
}
#endif

/**
 * remap_io_sg - remap an IO mapping to userspace
 * @vma: user vma to map to

Annotation

Implementation Notes