Fwd: [PATCH 1/4] resource.c: find the end of a E820 memory region

Philip Prindeville philipp at redfish-solutions.com
Thu Dec 22 03:25:08 EST 2011

There are some issues with linux-geode not accepting messages with multiple
recipients so I'm having to forward these to the list... Please add back the
original recipients when replying.

==== Original message follows ====

From: Philip Prindeville <philipp at redfish-solutions.com>
Date: Sun, 18 Dec 2011 12:05:32 -0700
Subject: [PATCH 1/4] resource.c: find the end of a E820 memory region
To: Ed Wildgoose <ed at wildgooses.com>,
    Andrew Morton <akpm at linux-foundation.org>,
    linux-geode at lists.infradead.org,
    Andres Salomon <dilinger at queued.net>
Cc: Nathan Williams <nathan at traverse.com.au>,
    Guy Ellis <guy at traverse.com.au>,
    David Woodhouse <dwmw2 at infradead.org>,
    Patrick Georgi <patrick.georgi at secunet.com>,
    Carl-Daniel Hailfinger <c-d.hailfinger.devel.2006 at gmx.net>,
    linux-mm at kvack.org

Add support for finding the end-boundary of an E820 region given an
address falling in one such region. This is precursory functionality
for Coreboot loader support.

Signed-off-by: Philip Prindeville <philipp at redfish-solutions.com>
Reviewed-by: Ed Wildgoose <ed at wildgooses.com>
Cc: Andrew Morton <akpm at linux-foundation.org>
Cc: Andres Salomon <dilinger at queued.net>
Cc: Nathan Williams <nathan at traverse.com.au>
Cc: Guy Ellis <guy at traverse.com.au>
Cc: David Woodhouse <dwmw2 at infradead.org>
Cc: Patrick Georgi <patrick.georgi at secunet.com>
Cc: Carl-Daniel Hailfinger <c-d.hailfinger.devel.2006 at gmx.net>
Cc: linux-geode at lists.infradead.org
Cc: linux-mm at kvack.org
 include/linux/ioport.h |    1 +
 kernel/resource.c      |   29 +++++++++++++++++++++++++++++
 2 files changed, 30 insertions(+), 0 deletions(-)

diff --git a/include/linux/ioport.h b/include/linux/ioport.h
index 9d57a71..962d5a5 100644
--- a/include/linux/ioport.h
+++ b/include/linux/ioport.h
@@ -223,6 +223,7 @@ extern struct resource * __devm_request_region(struct device *dev,
 extern void __devm_release_region(struct device *dev, struct resource *parent,
 				  resource_size_t start, resource_size_t n);
 extern int iomem_map_sanity_check(resource_size_t addr, unsigned long size);
+extern resource_size_t iomem_map_find_boundary(resource_size_t addr, int *mapped);
 extern int iomem_is_exclusive(u64 addr);
 extern int
diff --git a/kernel/resource.c b/kernel/resource.c
index 7640b3a..58e4fce 100644
--- a/kernel/resource.c
+++ b/kernel/resource.c
@@ -1057,6 +1057,35 @@ static int __init reserve_setup(char *str)
 __setup("reserve=", reserve_setup);
+ * Find the upper boundary for the region that this address falls in, and
+ * whether it's currently mapped or not.
+ */
+resource_size_t iomem_map_find_boundary(resource_size_t addr, int *mapped)
+	struct resource *p = &iomem_resource;
+	resource_size_t upper = 0;
+	loff_t l;
+	read_lock(&resource_lock);
+	for (p = p->child; p ; p = r_next(NULL, p, &l)) {
+		if (p->start > addr)
+			continue;
+		if (p->end < addr)
+			continue;
+		upper = p->end;
+		*mapped = ((p->flags & IORESOURCE_BUSY) != 0);
+		break;
+	}
+	read_unlock(&resource_lock);
+	return upper;
  * Check if the requested addr and size spans more than any slot in the
  * iomem resource tree.

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