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@amd.com>
Reviewed-by: Gregory Price <gourry@gourry.net>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Dave Jiang <dave.jiang@intel.com>
Reviewed-by: "Fabio M. De Francesco" <fabio.m.de.francesco@linux.intel.com>
Tested-by: Gregory Price <gourry@gourry.net>
Acked-by: Dan Williams <dan.j.williams@intel.com>
Link: https://patch.msgid.link/20250509150700.2817697-12-rrichter@amd.com
Signed-off-by: Dave Jiang <dave.jiang@intel.com>

diff --git a/drivers/cxl/core/region.c b/drivers/cxl/core/region.c
index 7def1c20b5f2b347c755d287b92b56914c02ccf4..20092d68d7a3940e4d1ef6dcf368ffb30a3a8966 100644 (file)
--- a/drivers/cxl/core/region.c
+++ b/drivers/cxl/core/region.c
@@ -3202,33 +3202,39 @@ err:
        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),
@@ -3236,7 +3242,7 @@ 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)