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drm/pagemap: Add DRM pagemap

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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: Matthew Brost <matthew.brost@intel.com>
Signed-off-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Reviewed-by: Matthew Brost <matthew.brost@intel.com>
Reviewed-by: Gwan-gyeong Mun <gwan-gyeong.mun@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20250306012657.3505757-5-matthew.brost@intel.com
This commit is contained in:
Thomas Hellström 2025-03-05 17:26:29 -08:00 committed by Matthew Brost
parent 1afaeb8293
commit 73463dac9b
1 changed files with 107 additions and 0 deletions
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107
include/drm/drm_pagemap.h Normal file
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/* 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