drivers/infiniband/hw/mlx5/mem.c

Source file repositories/reference/linux-study-clean/drivers/infiniband/hw/mlx5/mem.c

File Facts

System
Linux kernel
Corpus path
drivers/infiniband/hw/mlx5/mem.c
Extension
.c
Size
3264 bytes
Lines
97
Domain
Driver Families
Bucket
drivers/infiniband
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

#include <rdma/ib_umem_odp.h>
#include <rdma/iter.h>
#include "mlx5_ib.h"

/*
 * Fill in a physical address list. ib_umem_num_dma_blocks() entries will be
 * filled in the pas array.
 */
void mlx5_ib_populate_pas(struct ib_umem *umem, size_t page_size, __be64 *pas,
			  u64 access_flags)
{
	struct ib_block_iter biter;

	rdma_umem_for_each_dma_block (umem, &biter, page_size) {
		*pas = cpu_to_be64(rdma_block_iter_dma_address(&biter) |
				   access_flags);
		pas++;
	}
}

/*
 * Compute the page shift and page_offset for mailboxes that use a quantized
 * page_offset. The granulatity of the page offset scales according to page
 * size.
 */
unsigned long __mlx5_umem_find_best_quantized_pgoff(
	struct ib_umem *umem, unsigned long pgsz_bitmap,
	unsigned int page_offset_bits, u64 pgoff_bitmask, unsigned int scale,
	unsigned int *page_offset_quantized)
{
	const u64 page_offset_mask = (1UL << page_offset_bits) - 1;
	unsigned long page_size;
	u64 page_offset;

	page_size = ib_umem_find_best_pgoff(umem, pgsz_bitmap, pgoff_bitmask);
	if (!page_size)
		return 0;

	/*
	 * page size is the largest possible page size.
	 *
	 * Reduce the page_size, and thus the page_offset and quanta, until the
	 * page_offset fits into the mailbox field. Once page_size < scale this
	 * loop is guaranteed to terminate.
	 */
	page_offset = ib_umem_dma_offset(umem, page_size);
	while (page_offset & ~(u64)(page_offset_mask * (page_size / scale))) {
		page_size /= 2;
		page_offset = ib_umem_dma_offset(umem, page_size);
	}

	/*
	 * The address is not aligned, or otherwise cannot be represented by the
	 * page_offset.
	 */
	if (!(pgsz_bitmap & page_size))
		return 0;

	*page_offset_quantized =
		(unsigned long)page_offset / (page_size / scale);
	if (WARN_ON(*page_offset_quantized > page_offset_mask))
		return 0;
	return page_size;
}

Annotation

Implementation Notes