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Subject[PATCH v2 4/9] add devm_memremap_pages
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From: Christoph Hellwig <hch@lst.de>

This behaves like devm_memremap except that it ensures we have page
structures available that can back the region.

Signed-off-by: Christoph Hellwig <hch@lst.de>
[djbw: catch attempts to remap RAM, drop flags]
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
---
include/linux/io.h | 20 ++++++++++++++++++++
kernel/memremap.c | 53 ++++++++++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 73 insertions(+)

diff --git a/include/linux/io.h b/include/linux/io.h
index d8d749abd665..de64c1e53612 100644
--- a/include/linux/io.h
+++ b/include/linux/io.h
@@ -20,10 +20,13 @@

#include <linux/types.h>
#include <linux/init.h>
+#include <linux/bug.h>
+#include <linux/err.h>
#include <asm/io.h>
#include <asm/page.h>

struct device;
+struct resource;

__visible void __iowrite32_copy(void __iomem *to, const void *from, size_t count);
void __iowrite64_copy(void __iomem *to, const void *from, size_t count);
@@ -84,6 +87,23 @@ void *devm_memremap(struct device *dev, resource_size_t offset,
size_t size, unsigned long flags);
void devm_memunmap(struct device *dev, void *addr);

+void *__devm_memremap_pages(struct device *dev, struct resource *res);
+
+#ifdef CONFIG_ZONE_DEVICE
+void *devm_memremap_pages(struct device *dev, struct resource *res);
+#else
+static inline void *devm_memremap_pages(struct device *dev, struct resource *res)
+{
+ /*
+ * 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);
+}
+#endif
+
/*
* Some systems do not have legacy ISA devices.
* /dev/port is not a valid interface on these systems.
diff --git a/kernel/memremap.c b/kernel/memremap.c
index 5c9b55eaf121..72b0c66628b6 100644
--- a/kernel/memremap.c
+++ b/kernel/memremap.c
@@ -14,6 +14,7 @@
#include <linux/types.h>
#include <linux/io.h>
#include <linux/mm.h>
+#include <linux/memory_hotplug.h>

#ifndef ioremap_cache
/* temporary while we convert existing ioremap_cache users to memremap */
@@ -135,3 +136,55 @@ void devm_memunmap(struct device *dev, void *addr)
memunmap(addr);
}
EXPORT_SYMBOL(devm_memunmap);
+
+#ifdef CONFIG_ZONE_DEVICE
+struct page_map {
+ struct resource res;
+};
+
+static void devm_memremap_pages_release(struct device *dev, void *res)
+{
+ struct page_map *page_map = res;
+
+ /* pages are dead and unused, undo the arch mapping */
+ arch_remove_memory(page_map->res.start, resource_size(&page_map->res));
+}
+
+void *devm_memremap_pages(struct device *dev, struct resource *res)
+{
+ int is_ram = region_intersects(res->start, resource_size(res),
+ "System RAM");
+ struct page_map *page_map;
+ int error, nid;
+
+ if (is_ram == REGION_MIXED) {
+ WARN_ONCE(1, "%s attempted on mixed region %pr\n",
+ __func__, res);
+ return ERR_PTR(-ENXIO);
+ }
+
+ if (is_ram == REGION_INTERSECTS)
+ return __va(res->start);
+
+ page_map = devres_alloc(devm_memremap_pages_release,
+ sizeof(*page_map), GFP_KERNEL);
+ if (!page_map)
+ return ERR_PTR(-ENOMEM);
+
+ memcpy(&page_map->res, res, sizeof(*res));
+
+ nid = dev_to_node(dev);
+ if (nid < 0)
+ nid = 0;
+
+ error = arch_add_memory(nid, res->start, resource_size(res), true);
+ if (error) {
+ devres_free(page_map);
+ return ERR_PTR(error);
+ }
+
+ devres_add(dev, page_map);
+ return __va(res->start);
+}
+EXPORT_SYMBOL(devm_memremap_pages);
+#endif /* CONFIG_ZONE_DEVICE */


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