/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef _LINUX_MEMREMAP_H_
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#define _LINUX_MEMREMAP_H_
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#include <linux/range.h>
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#include <linux/ioport.h>
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#include <linux/percpu-refcount.h>
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struct resource;
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struct device;
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/**
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* struct vmem_altmap - pre-allocated storage for vmemmap_populate
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* @base_pfn: base of the entire dev_pagemap mapping
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* @reserve: pages mapped, but reserved for driver use (relative to @base)
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* @free: free pages set aside in the mapping for memmap storage
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* @align: pages reserved to meet allocation alignments
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* @alloc: track pages consumed, private to vmemmap_populate()
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*/
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struct vmem_altmap {
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const unsigned long base_pfn;
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const unsigned long end_pfn;
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const unsigned long reserve;
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unsigned long free;
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unsigned long align;
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unsigned long alloc;
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};
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/*
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* Specialize ZONE_DEVICE memory into multiple types each having differents
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* usage.
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*
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* MEMORY_DEVICE_PRIVATE:
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* Device memory that is not directly addressable by the CPU: CPU can neither
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* read nor write private memory. In this case, we do still have struct pages
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* backing the device memory. Doing so simplifies the implementation, but it is
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* important to remember that there are certain points at which the struct page
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* must be treated as an opaque object, rather than a "normal" struct page.
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*
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* A more complete discussion of unaddressable memory may be found in
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* include/linux/hmm.h and Documentation/vm/hmm.rst.
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*
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* MEMORY_DEVICE_FS_DAX:
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* Host memory that has similar access semantics as System RAM i.e. DMA
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* coherent and supports page pinning. In support of coordinating page
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* pinning vs other operations MEMORY_DEVICE_FS_DAX arranges for a
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* wakeup event whenever a page is unpinned and becomes idle. This
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* wakeup is used to coordinate physical address space management (ex:
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* fs truncate/hole punch) vs pinned pages (ex: device dma).
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*
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* MEMORY_DEVICE_GENERIC:
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* Host memory that has similar access semantics as System RAM i.e. DMA
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* coherent and supports page pinning. This is for example used by DAX devices
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* that expose memory using a character device.
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*
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* MEMORY_DEVICE_PCI_P2PDMA:
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* Device memory residing in a PCI BAR intended for use with Peer-to-Peer
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* transactions.
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*/
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enum memory_type {
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/* 0 is reserved to catch uninitialized type fields */
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MEMORY_DEVICE_PRIVATE = 1,
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MEMORY_DEVICE_FS_DAX,
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MEMORY_DEVICE_GENERIC,
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MEMORY_DEVICE_PCI_P2PDMA,
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};
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struct dev_pagemap_ops {
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/*
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* Called once the page refcount reaches 1. (ZONE_DEVICE pages never
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* reach 0 refcount unless there is a refcount bug. This allows the
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* device driver to implement its own memory management.)
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*/
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void (*page_free)(struct page *page);
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/*
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* Transition the refcount in struct dev_pagemap to the dead state.
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*/
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void (*kill)(struct dev_pagemap *pgmap);
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/*
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* Wait for refcount in struct dev_pagemap to be idle and reap it.
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*/
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void (*cleanup)(struct dev_pagemap *pgmap);
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/*
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* Used for private (un-addressable) device memory only. Must migrate
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* the page back to a CPU accessible page.
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*/
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vm_fault_t (*migrate_to_ram)(struct vm_fault *vmf);
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};
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#define PGMAP_ALTMAP_VALID (1 << 0)
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/**
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* struct dev_pagemap - metadata for ZONE_DEVICE mappings
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* @altmap: pre-allocated/reserved memory for vmemmap allocations
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* @ref: reference count that pins the devm_memremap_pages() mapping
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* @internal_ref: internal reference if @ref is not provided by the caller
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* @done: completion for @internal_ref
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* @type: memory type: see MEMORY_* in memory_hotplug.h
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* @flags: PGMAP_* flags to specify defailed behavior
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* @ops: method table
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* @owner: an opaque pointer identifying the entity that manages this
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* instance. Used by various helpers to make sure that no
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* foreign ZONE_DEVICE memory is accessed.
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* @nr_range: number of ranges to be mapped
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* @range: range to be mapped when nr_range == 1
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* @ranges: array of ranges to be mapped when nr_range > 1
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*/
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struct dev_pagemap {
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struct vmem_altmap altmap;
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struct percpu_ref *ref;
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struct percpu_ref internal_ref;
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struct completion done;
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enum memory_type type;
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unsigned int flags;
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const struct dev_pagemap_ops *ops;
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void *owner;
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int nr_range;
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union {
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struct range range;
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struct range ranges[0];
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};
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};
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static inline struct vmem_altmap *pgmap_altmap(struct dev_pagemap *pgmap)
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{
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if (pgmap->flags & PGMAP_ALTMAP_VALID)
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return &pgmap->altmap;
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return NULL;
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}
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#ifdef CONFIG_ZONE_DEVICE
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void *memremap_pages(struct dev_pagemap *pgmap, int nid);
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void memunmap_pages(struct dev_pagemap *pgmap);
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void *devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap);
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void devm_memunmap_pages(struct device *dev, struct dev_pagemap *pgmap);
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struct dev_pagemap *get_dev_pagemap(unsigned long pfn,
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struct dev_pagemap *pgmap);
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bool pgmap_pfn_valid(struct dev_pagemap *pgmap, unsigned long pfn);
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unsigned long vmem_altmap_offset(struct vmem_altmap *altmap);
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void vmem_altmap_free(struct vmem_altmap *altmap, unsigned long nr_pfns);
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unsigned long memremap_compat_align(void);
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#else
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static inline void *devm_memremap_pages(struct device *dev,
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struct dev_pagemap *pgmap)
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{
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/*
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* Fail attempts to call devm_memremap_pages() without
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* ZONE_DEVICE support enabled, this requires callers to fall
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* back to plain devm_memremap() based on config
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*/
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WARN_ON_ONCE(1);
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return ERR_PTR(-ENXIO);
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}
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static inline void devm_memunmap_pages(struct device *dev,
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struct dev_pagemap *pgmap)
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{
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}
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static inline struct dev_pagemap *get_dev_pagemap(unsigned long pfn,
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struct dev_pagemap *pgmap)
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{
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return NULL;
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}
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static inline bool pgmap_pfn_valid(struct dev_pagemap *pgmap, unsigned long pfn)
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{
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return false;
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}
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static inline unsigned long vmem_altmap_offset(struct vmem_altmap *altmap)
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{
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return 0;
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}
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static inline void vmem_altmap_free(struct vmem_altmap *altmap,
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unsigned long nr_pfns)
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{
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}
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/* when memremap_pages() is disabled all archs can remap a single page */
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static inline unsigned long memremap_compat_align(void)
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{
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return PAGE_SIZE;
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}
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#endif /* CONFIG_ZONE_DEVICE */
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static inline void put_dev_pagemap(struct dev_pagemap *pgmap)
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{
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if (pgmap)
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percpu_ref_put(pgmap->ref);
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}
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#endif /* _LINUX_MEMREMAP_H_ */
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