drivers/gpu/drm/msm/msm_iommu.c

Source file repositories/reference/linux-study-clean/drivers/gpu/drm/msm/msm_iommu.c

File Facts

System
Linux kernel
Corpus path
drivers/gpu/drm/msm/msm_iommu.c
Extension
.c
Size
21200 bytes
Lines
804
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 msm_iommu {
	struct msm_mmu base;
	struct iommu_domain *domain;

	struct mutex init_lock;  /* protects pagetables counter and prr_page */
	int pagetables;
	struct page *prr_page;

	struct kmem_cache *pt_cache;
};

#define to_msm_iommu(x) container_of(x, struct msm_iommu, base)

struct msm_iommu_pagetable {
	struct msm_mmu base;
	struct msm_mmu *parent;
	struct io_pgtable_ops *pgtbl_ops;
	const struct iommu_flush_ops *tlb;
	struct device *iommu_dev;
	unsigned long pgsize_bitmap;	/* Bitmap of page sizes in use */
	phys_addr_t ttbr;
	u32 asid;

	/** @root_page_table: Stores the root page table pointer. */
	void *root_page_table;
};
static struct msm_iommu_pagetable *to_pagetable(struct msm_mmu *mmu)
{
	return container_of(mmu, struct msm_iommu_pagetable, base);
}

/* based on iommu_pgsize() in iommu.c: */
static size_t calc_pgsize(struct msm_iommu_pagetable *pagetable,
			   unsigned long iova, phys_addr_t paddr,
			   size_t size, size_t *count)
{
	unsigned int pgsize_idx, pgsize_idx_next;
	unsigned long pgsizes;
	size_t offset, pgsize, pgsize_next;
	unsigned long addr_merge = paddr | iova;

	/* Page sizes supported by the hardware and small enough for @size */
	pgsizes = pagetable->pgsize_bitmap & GENMASK(__fls(size), 0);

	/* Constrain the page sizes further based on the maximum alignment */
	if (likely(addr_merge))
		pgsizes &= GENMASK(__ffs(addr_merge), 0);

	/* Make sure we have at least one suitable page size */
	BUG_ON(!pgsizes);

	/* Pick the biggest page size remaining */
	pgsize_idx = __fls(pgsizes);
	pgsize = BIT(pgsize_idx);
	if (!count)
		return pgsize;

	/* Find the next biggest support page size, if it exists */
	pgsizes = pagetable->pgsize_bitmap & ~GENMASK(pgsize_idx, 0);
	if (!pgsizes)
		goto out_set_count;

	pgsize_idx_next = __ffs(pgsizes);
	pgsize_next = BIT(pgsize_idx_next);

	/*
	 * There's no point trying a bigger page size unless the virtual
	 * and physical addresses are similarly offset within the larger page.
	 */
	if ((iova ^ paddr) & (pgsize_next - 1))
		goto out_set_count;

	/* Calculate the offset to the next page size alignment boundary */
	offset = pgsize_next - (addr_merge & (pgsize_next - 1));

	/*
	 * If size is big enough to accommodate the larger page, reduce
	 * the number of smaller pages.
	 */
	if (offset + pgsize_next <= size)
		size = offset;

out_set_count:
	*count = size >> pgsize_idx;
	return pgsize;
}

static int msm_iommu_pagetable_unmap(struct msm_mmu *mmu, u64 iova,
		size_t size)
{

Annotation

Implementation Notes