Commit 73463dac authored by Thomas Hellström's avatar Thomas Hellström Committed by Matthew Brost
Browse files

drm/pagemap: Add DRM pagemap 



Introduce drm_pagemap ops to map and unmap dma to VRAM resources. In the
local memory case it's a matter of merely providing an offset into the
device's physical address. For future p2p the map and unmap functions may
encode as needed.

Similar to how dma-buf works, let the memory provider (drm_pagemap) provide
the mapping functionality.

v3:
 - Move to drm level include
v4:
 - Fix kernel doc (G.G.)
v5:
 - s/map_dma/device_map (Thomas)
 - s/unmap_dma/device_unmap (Thomas)
v7:
 - Fix kernel doc (CI, Auld)
 - Drop P2P define (Thomas)

Signed-off-by: default avatarMatthew Brost <matthew.brost@intel.com>
Signed-off-by: default avatarThomas Hellström <thomas.hellstrom@linux.intel.com>
Reviewed-by: default avatarMatthew Brost <matthew.brost@intel.com>
Reviewed-by: default avatarGwan-gyeong Mun <gwan-gyeong.mun@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20250306012657.3505757-5-matthew.brost@intel.com
parent 1afaeb82

include/drm/drm_pagemap.h

0 → 100644
+107 −0
Original line number Diff line number Diff line 
/* SPDX-License-Identifier: MIT */

#ifndef _DRM_PAGEMAP_H_

#define _DRM_PAGEMAP_H_



#include <linux/dma-direction.h>

#include <linux/hmm.h>

#include <linux/types.h>



struct drm_pagemap;

struct device;



/**

 * enum drm_interconnect_protocol - Used to identify an interconnect protocol.

 *

 * @DRM_INTERCONNECT_SYSTEM: DMA map is system pages

 * @DRM_INTERCONNECT_DRIVER: DMA map is driver defined

 */

enum drm_interconnect_protocol {

	DRM_INTERCONNECT_SYSTEM,

	DRM_INTERCONNECT_DRIVER,

	/* A driver can add private values beyond DRM_INTERCONNECT_DRIVER */

};



/**

 * struct drm_pagemap_device_addr - Device address representation.

 * @addr: The dma address or driver-defined address for driver private interconnects.

 * @proto: The interconnect protocol.

 * @order: The page order of the device mapping. (Size is PAGE_SIZE << order).

 * @dir: The DMA direction.

 *

 * Note: There is room for improvement here. We should be able to pack into

 * 64 bits.

 */

struct drm_pagemap_device_addr {

	dma_addr_t addr;

	u64 proto : 54;

	u64 order : 8;

	u64 dir : 2;

};



/**

 * drm_pagemap_device_addr_encode() - Encode a dma address with metadata

 * @addr: The dma address or driver-defined address for driver private interconnects.

 * @proto: The interconnect protocol.

 * @order: The page order of the dma mapping. (Size is PAGE_SIZE << order).

 * @dir: The DMA direction.

 *

 * Return: A struct drm_pagemap_device_addr encoding the above information.

 */

static inline struct drm_pagemap_device_addr

drm_pagemap_device_addr_encode(dma_addr_t addr,

			       enum drm_interconnect_protocol proto,

			       unsigned int order,

			       enum dma_data_direction dir)

{

	return (struct drm_pagemap_device_addr) {

		.addr = addr,

		.proto = proto,

		.order = order,

		.dir = dir,

	};

}



/**

 * struct drm_pagemap_ops: Ops for a drm-pagemap.

 */

struct drm_pagemap_ops {

	/**

	 * @device_map: Map for device access or provide a virtual address suitable for

	 *

	 * @dpagemap: The struct drm_pagemap for the page.

	 * @dev: The device mapper.

	 * @page: The page to map.

	 * @order: The page order of the device mapping. (Size is PAGE_SIZE << order).

	 * @dir: The transfer direction.

	 */

	struct drm_pagemap_device_addr (*device_map)(struct drm_pagemap *dpagemap,

						     struct device *dev,

						     struct page *page,

						     unsigned int order,

						     enum dma_data_direction dir);



	/**

	 * @device_unmap: Unmap a device address previously obtained using @device_map.

	 *

	 * @dpagemap: The struct drm_pagemap for the mapping.

	 * @dev: The device unmapper.

	 * @addr: The device address obtained when mapping.

	 */

	void (*device_unmap)(struct drm_pagemap *dpagemap,

			     struct device *dev,

			     struct drm_pagemap_device_addr addr);



};



/**

 * struct drm_pagemap: Additional information for a struct dev_pagemap

 * used for device p2p handshaking.

 * @ops: The struct drm_pagemap_ops.

 * @dev: The struct drevice owning the device-private memory.

 */

struct drm_pagemap {

	const struct drm_pagemap_ops *ops;

	struct device *dev;

};



#endif