Thread (38 messages) 38 messages, 5 authors, 2015-08-06

[PATCH v3 05/24] arch: introduce memremap()

From: Luis R. Rodriguez <hidden>
Date: 2015-07-30 21:02:09
Also in: linux-arch, lkml, nvdimm

On Thu, Jul 30, 2015 at 12:54:07PM -0400, Dan Williams wrote:
quoted hunk ↗ jump to hunk
diff --git a/include/linux/io.h b/include/linux/io.h
index fb5a99800e77..3fcf6256c088 100644
--- a/include/linux/io.h
+++ b/include/linux/io.h
@@ -121,4 +121,13 @@ static inline int arch_phys_wc_index(int handle)
 #endif
 #endif
 
+enum {
+	/* See memremap() kernel-doc for usage description... */
+	MEMREMAP_WB = 1 << 0,
+	MEMREMAP_WT = 1 << 1,
+};
Same feedback for enum nameing and also kdoc style.
quoted hunk ↗ jump to hunk
diff --git a/kernel/memremap.c b/kernel/memremap.c
new file mode 100644
index 000000000000..27637f42f30d
--- /dev/null
+++ b/kernel/memremap.c
<-- ... -->
+/**
+ * memremap() - remap an iomem_resource as cacheable memory
+ * @offset: iomem resource start address
+ * @size: size of remap
+ * @flags: either MEMREMAP_WB or MEMREMAP_WT
+ *
+ * memremap() is "ioremap" for cases where it is known that the resource
+ * being mapped does not have i/o side effects and the __iomem
+ * annotation is not applicable.
+ *
+ * MEMREMAP_WB - matches the default mapping for "System RAM" on
+ * the architecture.  This is usually a read-allocate write-back cache.
+ * Morever, if MEMREMAP_WB is specified and the requested remap region is RAM
+ * memremap() will bypass establishing a new mapping and instead return
+ * a pointer into the direct map.
+ *
+ * MEMREMAP_WT - establish a mapping whereby writes either bypass the
+ * cache or are written through to memory and never exist in a
+ * cache-dirty state with respect to program visibility.  Attempts to
+ * map "System RAM" with this mapping type will fail.
Then you can extrend all this on kdoc on the enum.
+ */
+void *memremap(resource_size_t offset, size_t size, unsigned long flags)
+{
+	int is_ram = region_intersects(offset, size, "System RAM");
This could be the enum region_intersect_type, then if the region enum is
extended you'd get a compiler error if one type was not handled.

  Luis
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