[PATCH v3 5/7] resource: Introduce walk device_backed_vmemmap res() helper

[Li Zhijian <lizhijian@fujitsu.com>]

It walks resources registered with flags
(IORESOURCE_DEVICE_BACKED_VMEMMAP | IORESOURCE_BUSY), usually used by
device backed vmemmap region. currently, it only sticks to the
persistent memory type since it is only one user.

CC: Andrew Morton <akpm@linux-foundation.org>
CC: Baoquan He <bhe@redhat.com>
CC: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
CC: Alison Schofield <alison.schofield@intel.com>
CC: Dave Jiang <dave.jiang@intel.com>
CC: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Li Zhijian <lizhijian@fujitsu.com>
---
 include/linux/ioport.h |  3 +++
 kernel/resource.c      | 13 +++++++++++++
 2 files changed, 16 insertions(+)

diff --git a/include/linux/ioport.h b/include/linux/ioport.h
index 3b59e924f531..10a60227d6c2 100644
--- a/include/linux/ioport.h
+++ b/include/linux/ioport.h
@@ -332,6 +332,9 @@ extern int
 walk_system_ram_res(u64 start, u64 end, void *arg,
 		    int (*func)(struct resource *, void *));
 extern int
+walk_device_backed_vmemmap_res(u64 start, u64 end, void *arg,
+			       int (*func)(struct resource *, void *));
+extern int
 walk_system_ram_res_rev(u64 start, u64 end, void *arg,
 			int (*func)(struct resource *, void *));
 extern int
diff --git a/kernel/resource.c b/kernel/resource.c
index fcbca39dbc45..5f484266af07 100644
--- a/kernel/resource.c
+++ b/kernel/resource.c
@@ -431,6 +431,19 @@ int walk_system_ram_res(u64 start, u64 end, void *arg,
 				     func);
 }
 
+/*
+ * This function calls the @func callback against all memory ranges, which
+ * are ranges marked as (IORESOURCE_DEVICE_BACKED_VMEMMAP | IORESOURCE_BUSY)
+ * and IORES_DESC_PERSISTENT_MEMORY.
+ */
+int walk_device_backed_vmemmap_res(u64 start, u64 end, void *arg,
+			int (*func)(struct resource *, void *))
+{
+	return __walk_iomem_res_desc(start, end,
+			IORESOURCE_DEVICE_BACKED_VMEMMAP | IORESOURCE_BUSY,
+			IORES_DESC_PERSISTENT_MEMORY, arg, func);
+}
+
 /*
  * This function, being a variant of walk_system_ram_res(), calls the @func
  * callback against all memory ranges of type System RAM which are marked as
-- 
2.29.2