netdev - [PATCH v15 21/22] cxl: Add function for obtaining region range

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Message-ID: <20250512161055.4100442-22-alejandro.lucero-palau@amd.com>
Date: Mon, 12 May 2025 17:10:54 +0100
From: <alejandro.lucero-palau@....com>
To: <linux-cxl@...r.kernel.org>, <netdev@...r.kernel.org>,
	<dan.j.williams@...el.com>, <edward.cree@....com>, <davem@...emloft.net>,
	<kuba@...nel.org>, <pabeni@...hat.com>, <edumazet@...gle.com>,
	<dave.jiang@...el.com>
CC: Alejandro Lucero <alucerop@....com>, Zhi Wang <zhiw@...dia.com>, "Jonathan
 Cameron" <Jonathan.Cameron@...wei.com>
Subject: [PATCH v15 21/22] cxl: Add function for obtaining region range

From: Alejandro Lucero <alucerop@....com>

A CXL region struct contains the physical address to work with.

Type2 drivers can create a CXL region but have not access to the
related struct as it is defined as private by the kernel CXL core.
Add a function for getting the cxl region range to be used for mapping
such memory range by a Type2 driver.

Signed-off-by: Alejandro Lucero <alucerop@....com>
Reviewed-by: Zhi Wang <zhiw@...dia.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@...wei.com>
Reviewed-by: Dave Jiang <dave.jiang@...el.com>
---
 drivers/cxl/core/region.c | 23 +++++++++++++++++++++++
 include/cxl/cxl.h         |  2 ++
 2 files changed, 25 insertions(+)

diff --git a/drivers/cxl/core/region.c b/drivers/cxl/core/region.c
index c9d21d95ed19..64ec643c2e5a 100644
--- a/drivers/cxl/core/region.c
+++ b/drivers/cxl/core/region.c
@@ -2745,6 +2745,29 @@ static struct cxl_region *devm_cxl_add_region(struct cxl_root_decoder *cxlrd,
 	return ERR_PTR(rc);
 }
 
+/**
+ * cxl_get_region_range - obtain range linked to a CXL region
+ *
+ * @region: a pointer to struct cxl_region
+ * @range: a pointer to a struct range to be set
+ *
+ * Returns 0 or error.
+ */
+int cxl_get_region_range(struct cxl_region *region, struct range *range)
+{
+	if (WARN_ON_ONCE(!region))
+		return -ENODEV;
+
+	if (!region->params.res)
+		return -ENOSPC;
+
+	range->start = region->params.res->start;
+	range->end = region->params.res->end;
+
+	return 0;
+}
+EXPORT_SYMBOL_NS_GPL(cxl_get_region_range, "CXL");
+
 static ssize_t __create_region_show(struct cxl_root_decoder *cxlrd, char *buf)
 {
 	return sysfs_emit(buf, "region%u\n", atomic_read(&cxlrd->region_id));
diff --git a/include/cxl/cxl.h b/include/cxl/cxl.h
index c93b2f37a4fd..55442f84bd55 100644
--- a/include/cxl/cxl.h
+++ b/include/cxl/cxl.h
@@ -287,4 +287,6 @@ struct cxl_region *cxl_create_region(struct cxl_root_decoder *cxlrd,
 				     bool no_dax);
 
 int cxl_accel_region_detach(struct cxl_endpoint_decoder *cxled);
+struct range;
+int cxl_get_region_range(struct cxl_region *region, struct range *range);
 #endif /* __CXL_CXL_H__ */
-- 
2.34.1