1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef _LINUX_MEMREMAP_H_
3 #define _LINUX_MEMREMAP_H_
4 #include <linux/ioport.h>
5 #include <linux/percpu-refcount.h>
11 * struct vmem_altmap - pre-allocated storage for vmemmap_populate
12 * @base_pfn: base of the entire dev_pagemap mapping
13 * @reserve: pages mapped, but reserved for driver use (relative to @base)
14 * @free: free pages set aside in the mapping for memmap storage
15 * @align: pages reserved to meet allocation alignments
16 * @alloc: track pages consumed, private to vmemmap_populate()
19 const unsigned long base_pfn;
20 const unsigned long reserve;
27 * Specialize ZONE_DEVICE memory into multiple types each having differents
30 * MEMORY_DEVICE_PRIVATE:
31 * Device memory that is not directly addressable by the CPU: CPU can neither
32 * read nor write private memory. In this case, we do still have struct pages
33 * backing the device memory. Doing so simplifies the implementation, but it is
34 * important to remember that there are certain points at which the struct page
35 * must be treated as an opaque object, rather than a "normal" struct page.
37 * A more complete discussion of unaddressable memory may be found in
38 * include/linux/hmm.h and Documentation/vm/hmm.rst.
40 * MEMORY_DEVICE_FS_DAX:
41 * Host memory that has similar access semantics as System RAM i.e. DMA
42 * coherent and supports page pinning. In support of coordinating page
43 * pinning vs other operations MEMORY_DEVICE_FS_DAX arranges for a
44 * wakeup event whenever a page is unpinned and becomes idle. This
45 * wakeup is used to coordinate physical address space management (ex:
46 * fs truncate/hole punch) vs pinned pages (ex: device dma).
48 * MEMORY_DEVICE_PCI_P2PDMA:
49 * Device memory residing in a PCI BAR intended for use with Peer-to-Peer
53 MEMORY_DEVICE_PRIVATE = 1,
55 MEMORY_DEVICE_PCI_P2PDMA,
59 * Additional notes about MEMORY_DEVICE_PRIVATE may be found in
60 * include/linux/hmm.h and Documentation/vm/hmm.rst. There is also a brief
61 * explanation in include/linux/memory_hotplug.h.
63 * The page_free() callback is called once the page refcount reaches 1
64 * (ZONE_DEVICE pages never reach 0 refcount unless there is a refcount bug.
65 * This allows the device driver to implement its own memory management.)
67 typedef void (*dev_page_free_t)(struct page *page, void *data);
70 * struct dev_pagemap - metadata for ZONE_DEVICE mappings
71 * @page_free: free page callback when page refcount reaches 1
72 * @altmap: pre-allocated/reserved memory for vmemmap allocations
73 * @res: physical address range covered by @ref
74 * @ref: reference count that pins the devm_memremap_pages() mapping
75 * @kill: callback to transition @ref to the dead state
76 * @cleanup: callback to wait for @ref to be idle and reap it
77 * @dev: host device of the mapping for debug
78 * @data: private data pointer for page_free()
79 * @type: memory type: see MEMORY_* in memory_hotplug.h
82 dev_page_free_t page_free;
83 struct vmem_altmap altmap;
86 struct percpu_ref *ref;
87 void (*kill)(struct percpu_ref *ref);
88 void (*cleanup)(struct percpu_ref *ref);
91 enum memory_type type;
92 u64 pci_p2pdma_bus_offset;
95 #ifdef CONFIG_ZONE_DEVICE
96 void *devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap);
97 void devm_memunmap_pages(struct device *dev, struct dev_pagemap *pgmap);
98 struct dev_pagemap *get_dev_pagemap(unsigned long pfn,
99 struct dev_pagemap *pgmap);
101 unsigned long vmem_altmap_offset(struct vmem_altmap *altmap);
102 void vmem_altmap_free(struct vmem_altmap *altmap, unsigned long nr_pfns);
104 static inline void *devm_memremap_pages(struct device *dev,
105 struct dev_pagemap *pgmap)
108 * Fail attempts to call devm_memremap_pages() without
109 * ZONE_DEVICE support enabled, this requires callers to fall
110 * back to plain devm_memremap() based on config
113 return ERR_PTR(-ENXIO);
116 static inline void devm_memunmap_pages(struct device *dev,
117 struct dev_pagemap *pgmap)
121 static inline struct dev_pagemap *get_dev_pagemap(unsigned long pfn,
122 struct dev_pagemap *pgmap)
127 static inline unsigned long vmem_altmap_offset(struct vmem_altmap *altmap)
132 static inline void vmem_altmap_free(struct vmem_altmap *altmap,
133 unsigned long nr_pfns)
136 #endif /* CONFIG_ZONE_DEVICE */
138 static inline void put_dev_pagemap(struct dev_pagemap *pgmap)
141 percpu_ref_put(pgmap->ref);
143 #endif /* _LINUX_MEMREMAP_H_ */