linux-kernel - [PATCH v5 11/14] cxl/region: Add function to find a port's switch decoder by range

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Message-ID: <20250428214318.1682212-12-rrichter@amd.com>
Date: Mon, 28 Apr 2025 23:43:14 +0200
From: Robert Richter <rrichter@....com>
To: Alison Schofield <alison.schofield@...el.com>, Vishal Verma
	<vishal.l.verma@...el.com>, Ira Weiny <ira.weiny@...el.com>, Dan Williams
	<dan.j.williams@...el.com>, Jonathan Cameron <Jonathan.Cameron@...wei.com>,
	Dave Jiang <dave.jiang@...el.com>, Davidlohr Bueso <dave@...olabs.net>
CC: <linux-cxl@...r.kernel.org>, <linux-kernel@...r.kernel.org>, Gregory Price
	<gourry@...rry.net>, "Fabio M. De Francesco"
	<fabio.m.de.francesco@...ux.intel.com>, Terry Bowman <terry.bowman@....com>,
	Robert Richter <rrichter@....com>
Subject: [PATCH v5 11/14] cxl/region: Add function to find a port's switch decoder by range

Factor out code to find the switch decoder of a port for a specific
address range. Reuse the code to search a root decoder, create the
function cxl_port_find_switch_decoder() and rework
match_root_decoder_by_range() to be usable for switch decoders too.

Signed-off-by: Robert Richter <rrichter@....com>
Reviewed-by: Gregory Price <gourry@...rry.net>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@...wei.com>
Reviewed-by: Dave Jiang <dave.jiang@...el.com>
Tested-by: Gregory Price <gourry@...rry.net>
---
 drivers/cxl/core/region.c | 30 ++++++++++++++++++------------
 1 file changed, 18 insertions(+), 12 deletions(-)

diff --git a/drivers/cxl/core/region.c b/drivers/cxl/core/region.c
index a292d5c4c4a9..ef5408301714 100644
--- a/drivers/cxl/core/region.c
+++ b/drivers/cxl/core/region.c
@@ -3205,33 +3205,39 @@ static int devm_cxl_add_dax_region(struct cxl_region *cxlr)
 	return rc;
 }
 
-static int match_root_decoder_by_range(struct device *dev,
-				       const void *data)
+static int match_decoder_by_range(struct device *dev, const void *data)
 {
 	const struct range *r1, *r2 = data;
-	struct cxl_root_decoder *cxlrd;
+	struct cxl_decoder *cxld;
 
-	if (!is_root_decoder(dev))
+	if (!is_switch_decoder(dev))
 		return 0;
 
-	cxlrd = to_cxl_root_decoder(dev);
-	r1 = &cxlrd->cxlsd.cxld.hpa_range;
+	cxld = to_cxl_decoder(dev);
+	r1 = &cxld->hpa_range;
 	return range_contains(r1, r2);
 }
 
+static struct cxl_decoder *
+cxl_port_find_switch_decoder(struct cxl_port *port, struct range *hpa)
+{
+	struct device *cxld_dev = device_find_child(&port->dev, hpa,
+						    match_decoder_by_range);
+
+	return cxld_dev ? to_cxl_decoder(cxld_dev) : NULL;
+}
+
 static struct cxl_root_decoder *
 cxl_find_root_decoder(struct cxl_endpoint_decoder *cxled)
 {
 	struct cxl_memdev *cxlmd = cxled_to_memdev(cxled);
 	struct cxl_port *port = cxled_to_port(cxled);
 	struct cxl_root *cxl_root __free(put_cxl_root) = find_cxl_root(port);
-	struct cxl_decoder *cxld = &cxled->cxld;
+	struct cxl_decoder *root, *cxld = &cxled->cxld;
 	struct range *hpa = &cxld->hpa_range;
-	struct device *cxlrd_dev;
 
-	cxlrd_dev = device_find_child(&cxl_root->port.dev, hpa,
-				      match_root_decoder_by_range);
-	if (!cxlrd_dev) {
+	root = cxl_port_find_switch_decoder(&cxl_root->port, hpa);
+	if (!root) {
 		dev_err(cxlmd->dev.parent,
 			"%s:%s no CXL window for range %#llx:%#llx\n",
 			dev_name(&cxlmd->dev), dev_name(&cxld->dev),
@@ -3239,7 +3245,7 @@ cxl_find_root_decoder(struct cxl_endpoint_decoder *cxled)
 		return NULL;
 	}
 
-	return to_cxl_root_decoder(cxlrd_dev);
+	return to_cxl_root_decoder(&root->dev);
 }
 
 static int match_region_by_range(struct device *dev, const void *data)
-- 
2.39.5