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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> 6 : : 7 : : struct resource; 8 : : struct device; 9 : : 10 : : /** 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() 17 : : */ 18 : : struct vmem_altmap { 19 : : const unsigned long base_pfn; 20 : : const unsigned long end_pfn; 21 : : const unsigned long reserve; 22 : : unsigned long free; 23 : : unsigned long align; 24 : : unsigned long alloc; 25 : : }; 26 : : 27 : : /* 28 : : * Specialize ZONE_DEVICE memory into multiple types each having differents 29 : : * usage. 30 : : * 31 : : * MEMORY_DEVICE_PRIVATE: 32 : : * Device memory that is not directly addressable by the CPU: CPU can neither 33 : : * read nor write private memory. In this case, we do still have struct pages 34 : : * backing the device memory. Doing so simplifies the implementation, but it is 35 : : * important to remember that there are certain points at which the struct page 36 : : * must be treated as an opaque object, rather than a "normal" struct page. 37 : : * 38 : : * A more complete discussion of unaddressable memory may be found in 39 : : * include/linux/hmm.h and Documentation/vm/hmm.rst. 40 : : * 41 : : * MEMORY_DEVICE_FS_DAX: 42 : : * Host memory that has similar access semantics as System RAM i.e. DMA 43 : : * coherent and supports page pinning. In support of coordinating page 44 : : * pinning vs other operations MEMORY_DEVICE_FS_DAX arranges for a 45 : : * wakeup event whenever a page is unpinned and becomes idle. This 46 : : * wakeup is used to coordinate physical address space management (ex: 47 : : * fs truncate/hole punch) vs pinned pages (ex: device dma). 48 : : * 49 : : * MEMORY_DEVICE_DEVDAX: 50 : : * Host memory that has similar access semantics as System RAM i.e. DMA 51 : : * coherent and supports page pinning. In contrast to 52 : : * MEMORY_DEVICE_FS_DAX, this memory is access via a device-dax 53 : : * character device. 54 : : * 55 : : * MEMORY_DEVICE_PCI_P2PDMA: 56 : : * Device memory residing in a PCI BAR intended for use with Peer-to-Peer 57 : : * transactions. 58 : : */ 59 : : enum memory_type { 60 : : /* 0 is reserved to catch uninitialized type fields */ 61 : : MEMORY_DEVICE_PRIVATE = 1, 62 : : MEMORY_DEVICE_FS_DAX, 63 : : MEMORY_DEVICE_DEVDAX, 64 : : MEMORY_DEVICE_PCI_P2PDMA, 65 : : }; 66 : : 67 : : struct dev_pagemap_ops { 68 : : /* 69 : : * Called once the page refcount reaches 1. (ZONE_DEVICE pages never 70 : : * reach 0 refcount unless there is a refcount bug. This allows the 71 : : * device driver to implement its own memory management.) 72 : : */ 73 : : void (*page_free)(struct page *page); 74 : : 75 : : /* 76 : : * Transition the refcount in struct dev_pagemap to the dead state. 77 : : */ 78 : : void (*kill)(struct dev_pagemap *pgmap); 79 : : 80 : : /* 81 : : * Wait for refcount in struct dev_pagemap to be idle and reap it. 82 : : */ 83 : : void (*cleanup)(struct dev_pagemap *pgmap); 84 : : 85 : : /* 86 : : * Used for private (un-addressable) device memory only. Must migrate 87 : : * the page back to a CPU accessible page. 88 : : */ 89 : : vm_fault_t (*migrate_to_ram)(struct vm_fault *vmf); 90 : : }; 91 : : 92 : : #define PGMAP_ALTMAP_VALID (1 << 0) 93 : : 94 : : /** 95 : : * struct dev_pagemap - metadata for ZONE_DEVICE mappings 96 : : * @altmap: pre-allocated/reserved memory for vmemmap allocations 97 : : * @res: physical address range covered by @ref 98 : : * @ref: reference count that pins the devm_memremap_pages() mapping 99 : : * @internal_ref: internal reference if @ref is not provided by the caller 100 : : * @done: completion for @internal_ref 101 : : * @dev: host device of the mapping for debug 102 : : * @data: private data pointer for page_free() 103 : : * @type: memory type: see MEMORY_* in memory_hotplug.h 104 : : * @flags: PGMAP_* flags to specify defailed behavior 105 : : * @ops: method table 106 : : */ 107 : : struct dev_pagemap { 108 : : struct vmem_altmap altmap; 109 : : struct resource res; 110 : : struct percpu_ref *ref; 111 : : struct percpu_ref internal_ref; 112 : : struct completion done; 113 : : enum memory_type type; 114 : : unsigned int flags; 115 : : const struct dev_pagemap_ops *ops; 116 : : }; 117 : : 118 : : static inline struct vmem_altmap *pgmap_altmap(struct dev_pagemap *pgmap) 119 : : { 120 : : if (pgmap->flags & PGMAP_ALTMAP_VALID) 121 : : return &pgmap->altmap; 122 : : return NULL; 123 : : } 124 : : 125 : : #ifdef CONFIG_ZONE_DEVICE 126 : : void *memremap_pages(struct dev_pagemap *pgmap, int nid); 127 : : void memunmap_pages(struct dev_pagemap *pgmap); 128 : : void *devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap); 129 : : void devm_memunmap_pages(struct device *dev, struct dev_pagemap *pgmap); 130 : : struct dev_pagemap *get_dev_pagemap(unsigned long pfn, 131 : : struct dev_pagemap *pgmap); 132 : : 133 : : unsigned long vmem_altmap_offset(struct vmem_altmap *altmap); 134 : : void vmem_altmap_free(struct vmem_altmap *altmap, unsigned long nr_pfns); 135 : : #else 136 : : static inline void *devm_memremap_pages(struct device *dev, 137 : : struct dev_pagemap *pgmap) 138 : : { 139 : : /* 140 : : * Fail attempts to call devm_memremap_pages() without 141 : : * ZONE_DEVICE support enabled, this requires callers to fall 142 : : * back to plain devm_memremap() based on config 143 : : */ 144 : : WARN_ON_ONCE(1); 145 : : return ERR_PTR(-ENXIO); 146 : : } 147 : : 148 : : static inline void devm_memunmap_pages(struct device *dev, 149 : : struct dev_pagemap *pgmap) 150 : : { 151 : : } 152 : : 153 : 0 : static inline struct dev_pagemap *get_dev_pagemap(unsigned long pfn, 154 : : struct dev_pagemap *pgmap) 155 : : { 156 : 0 : return NULL; 157 : : } 158 : : 159 : : static inline unsigned long vmem_altmap_offset(struct vmem_altmap *altmap) 160 : : { 161 : : return 0; 162 : : } 163 : : 164 : : static inline void vmem_altmap_free(struct vmem_altmap *altmap, 165 : : unsigned long nr_pfns) 166 : : { 167 : : } 168 : : #endif /* CONFIG_ZONE_DEVICE */ 169 : : 170 : 0 : static inline void put_dev_pagemap(struct dev_pagemap *pgmap) 171 : : { 172 : 0 : if (pgmap) 173 : 0 : percpu_ref_put(pgmap->ref); 174 : 0 : } 175 : : #endif /* _LINUX_MEMREMAP_H_ */