include/linux/memremap.h

   1 #ifndef _LINUX_MEMREMAP_H_
   2 #define _LINUX_MEMREMAP_H_
   3 #include <linux/mm.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 reserve;
  21         unsigned long free;
  22         unsigned long align;
  23         unsigned long alloc;
  24 };
  25
  26 unsigned long vmem_altmap_offset(struct vmem_altmap *altmap);
  27 void vmem_altmap_free(struct vmem_altmap *altmap, unsigned long nr_pfns);
  28
  29 #ifdef CONFIG_ZONE_DEVICE
  30 struct vmem_altmap *to_vmem_altmap(unsigned long memmap_start);
  31 #else
  32 static inline struct vmem_altmap *to_vmem_altmap(unsigned long memmap_start)
  33 {
  34         return NULL;
  35 }
  36 #endif
  37
  38 /**
  39  * struct dev_pagemap - metadata for ZONE_DEVICE mappings
  40  * @altmap: pre-allocated/reserved memory for vmemmap allocations
  41  * @res: physical address range covered by @ref
  42  * @ref: reference count that pins the devm_memremap_pages() mapping
  43  * @dev: host device of the mapping for debug
  44  */
  45 struct dev_pagemap {
  46         struct vmem_altmap *altmap;
  47         const struct resource *res;
  48         struct percpu_ref *ref;
  49         struct device *dev;
  50 };
  51
  52 #ifdef CONFIG_ZONE_DEVICE
  53 void *devm_memremap_pages(struct device *dev, struct resource *res,
  54                 struct percpu_ref *ref, struct vmem_altmap *altmap);
  55 struct dev_pagemap *find_dev_pagemap(resource_size_t phys);
  56 #else
  57 static inline void *devm_memremap_pages(struct device *dev,
  58                 struct resource *res, struct percpu_ref *ref,
  59                 struct vmem_altmap *altmap)
  60 {
  61         /*
  62          * Fail attempts to call devm_memremap_pages() without
  63          * ZONE_DEVICE support enabled, this requires callers to fall
  64          * back to plain devm_memremap() based on config
  65          */
  66         WARN_ON_ONCE(1);
  67         return ERR_PTR(-ENXIO);
  68 }
  69
  70 static inline struct dev_pagemap *find_dev_pagemap(resource_size_t phys)
  71 {
  72         return NULL;
  73 }
  74 #endif
  75
  76 /**
  77  * get_dev_pagemap() - take a new live reference on the dev_pagemap for @pfn
  78  * @pfn: page frame number to lookup page_map
  79  * @pgmap: optional known pgmap that already has a reference
  80  *
  81  * @pgmap allows the overhead of a lookup to be bypassed when @pfn lands in the
  82  * same mapping.
  83  */
  84 static inline struct dev_pagemap *get_dev_pagemap(unsigned long pfn,
  85                 struct dev_pagemap *pgmap)
  86 {
  87         const struct resource *res = pgmap ? pgmap->res : NULL;
  88         resource_size_t phys = PFN_PHYS(pfn);
  89
  90         /*
  91          * In the cached case we're already holding a live reference so
  92          * we can simply do a blind increment
  93          */
  94         if (res && phys >= res->start && phys <= res->end) {
  95                 percpu_ref_get(pgmap->ref);
  96                 return pgmap;
  97         }
  98
  99         /* fall back to slow path lookup */
 100         rcu_read_lock();
 101         pgmap = find_dev_pagemap(phys);
 102         if (pgmap && !percpu_ref_tryget_live(pgmap->ref))
 103                 pgmap = NULL;
 104         rcu_read_unlock();
 105
 106         return pgmap;
 107 }
 108
 109 static inline void put_dev_pagemap(struct dev_pagemap *pgmap)
 110 {
 111         if (pgmap)
 112                 percpu_ref_put(pgmap->ref);
 113 }
 114 #endif /* _LINUX_MEMREMAP_H_ */