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-rw-r--r--include/linux/memremap.h114
1 files changed, 114 insertions, 0 deletions
diff --git a/include/linux/memremap.h b/include/linux/memremap.h
new file mode 100644
index 000000000..bcaa63413
--- /dev/null
+++ b/include/linux/memremap.h
@@ -0,0 +1,114 @@
+#ifndef _LINUX_MEMREMAP_H_
+#define _LINUX_MEMREMAP_H_
+#include <linux/mm.h>
+#include <linux/ioport.h>
+#include <linux/percpu-refcount.h>
+
+struct resource;
+struct device;
+
+/**
+ * struct vmem_altmap - pre-allocated storage for vmemmap_populate
+ * @base_pfn: base of the entire dev_pagemap mapping
+ * @reserve: pages mapped, but reserved for driver use (relative to @base)
+ * @free: free pages set aside in the mapping for memmap storage
+ * @align: pages reserved to meet allocation alignments
+ * @alloc: track pages consumed, private to vmemmap_populate()
+ */
+struct vmem_altmap {
+ const unsigned long base_pfn;
+ const unsigned long reserve;
+ unsigned long free;
+ unsigned long align;
+ unsigned long alloc;
+};
+
+unsigned long vmem_altmap_offset(struct vmem_altmap *altmap);
+void vmem_altmap_free(struct vmem_altmap *altmap, unsigned long nr_pfns);
+
+#if defined(CONFIG_SPARSEMEM_VMEMMAP) && defined(CONFIG_ZONE_DEVICE)
+struct vmem_altmap *to_vmem_altmap(unsigned long memmap_start);
+#else
+static inline struct vmem_altmap *to_vmem_altmap(unsigned long memmap_start)
+{
+ return NULL;
+}
+#endif
+
+/**
+ * struct dev_pagemap - metadata for ZONE_DEVICE mappings
+ * @altmap: pre-allocated/reserved memory for vmemmap allocations
+ * @res: physical address range covered by @ref
+ * @ref: reference count that pins the devm_memremap_pages() mapping
+ * @dev: host device of the mapping for debug
+ */
+struct dev_pagemap {
+ struct vmem_altmap *altmap;
+ const struct resource *res;
+ struct percpu_ref *ref;
+ struct device *dev;
+};
+
+#ifdef CONFIG_ZONE_DEVICE
+void *devm_memremap_pages(struct device *dev, struct resource *res,
+ struct percpu_ref *ref, struct vmem_altmap *altmap);
+struct dev_pagemap *find_dev_pagemap(resource_size_t phys);
+#else
+static inline void *devm_memremap_pages(struct device *dev,
+ struct resource *res, struct percpu_ref *ref,
+ struct vmem_altmap *altmap)
+{
+ /*
+ * Fail attempts to call devm_memremap_pages() without
+ * ZONE_DEVICE support enabled, this requires callers to fall
+ * back to plain devm_memremap() based on config
+ */
+ WARN_ON_ONCE(1);
+ return ERR_PTR(-ENXIO);
+}
+
+static inline struct dev_pagemap *find_dev_pagemap(resource_size_t phys)
+{
+ return NULL;
+}
+#endif
+
+/**
+ * get_dev_pagemap() - take a new live reference on the dev_pagemap for @pfn
+ * @pfn: page frame number to lookup page_map
+ * @pgmap: optional known pgmap that already has a reference
+ *
+ * @pgmap allows the overhead of a lookup to be bypassed when @pfn lands in the
+ * same mapping.
+ */
+static inline struct dev_pagemap *get_dev_pagemap(unsigned long pfn,
+ struct dev_pagemap *pgmap)
+{
+ const struct resource *res = pgmap ? pgmap->res : NULL;
+ resource_size_t phys = PFN_PHYS(pfn);
+
+ /*
+ * In the cached case we're already holding a live reference so
+ * we can simply do a blind increment
+ */
+ if (res && phys >= res->start && phys <= res->end) {
+ percpu_ref_get(pgmap->ref);
+ return pgmap;
+ }
+
+ /* fall back to slow path lookup */
+ rcu_read_lock();
+ pgmap = find_dev_pagemap(phys);
+ if (pgmap && !percpu_ref_tryget_live(pgmap->ref))
+ pgmap = NULL;
+ rcu_read_unlock();
+
+ return pgmap;
+}
+
+static inline void put_dev_pagemap(struct dev_pagemap *pgmap)
+{
+ if (pgmap)
+ percpu_ref_put(pgmap->ref);
+}
+#endif /* _LINUX_MEMREMAP_H_ */