cxl/region: Move cxl_dpa_to_region() work to the region driver

This helper belongs in the region driver as it is only useful
with CONFIG_CXL_REGION. Add a stub in core.h for when the region
driver is not built.

Signed-off-by: Alison Schofield <alison.schofield@intel.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Ira Weiny <ira.weiny@intel.com>
Link: https://lore.kernel.org/r/05e30f788d62b3dd398aff2d2ea50a6aaa7c3313.1714496730.git.alison.schofield@intel.com
Signed-off-by: Dave Jiang <dave.jiang@intel.com>

Author: AlisonSchofield

drivers/cxl/core/core.h

@@ -27,7 +27,14 @@ void cxl_decoder_kill_region(struct cxl_endpoint_decoder *cxled);
 int cxl_region_init(void);
 void cxl_region_exit(void);
 int cxl_get_poison_by_endpoint(struct cxl_port *port);
+struct cxl_region *cxl_dpa_to_region(const struct cxl_memdev *cxlmd, u64 dpa);
+
 #else
+static inline
+struct cxl_region *cxl_dpa_to_region(const struct cxl_memdev *cxlmd, u64 dpa)
+{
+	return NULL;
+}
 static inline int cxl_get_poison_by_endpoint(struct cxl_port *port)
 {
 	return 0;

drivers/cxl/core/memdev.c

@@ -251,50 +251,6 @@ int cxl_trigger_poison_list(struct cxl_memdev *cxlmd)
 }
 EXPORT_SYMBOL_NS_GPL(cxl_trigger_poison_list, CXL);
 
-struct cxl_dpa_to_region_context {
-	struct cxl_region *cxlr;
-	u64 dpa;
-};
-
-static int __cxl_dpa_to_region(struct device *dev, void *arg)
-{
-	struct cxl_dpa_to_region_context *ctx = arg;
-	struct cxl_endpoint_decoder *cxled;
-	u64 dpa = ctx->dpa;
-
-	if (!is_endpoint_decoder(dev))
-		return 0;
-
-	cxled = to_cxl_endpoint_decoder(dev);
-	if (!cxled->dpa_res || !resource_size(cxled->dpa_res))
-		return 0;
-
-	if (dpa > cxled->dpa_res->end || dpa < cxled->dpa_res->start)
-		return 0;
-
-	dev_dbg(dev, "dpa:0x%llx mapped in region:%s\n", dpa,
-		dev_name(&cxled->cxld.region->dev));
-
-	ctx->cxlr = cxled->cxld.region;
-
-	return 1;
-}
-
-static struct cxl_region *cxl_dpa_to_region(struct cxl_memdev *cxlmd, u64 dpa)
-{
-	struct cxl_dpa_to_region_context ctx;
-	struct cxl_port *port;
-
-	ctx = (struct cxl_dpa_to_region_context) {
-		.dpa = dpa,
-	};
-	port = cxlmd->endpoint;
-	if (port && is_cxl_endpoint(port) && cxl_num_decoders_committed(port))
-		device_for_each_child(&port->dev, &ctx, __cxl_dpa_to_region);
-
-	return ctx.cxlr;
-}
-
 static int cxl_validate_poison_dpa(struct cxl_memdev *cxlmd, u64 dpa)
 {
 	struct cxl_dev_state *cxlds = cxlmd->cxlds;

drivers/cxl/core/region.c

@@ -2679,6 +2679,50 @@ int cxl_get_poison_by_endpoint(struct cxl_port *port)
 	return rc;
 }
 
+struct cxl_dpa_to_region_context {
+	struct cxl_region *cxlr;
+	u64 dpa;
+};
+
+static int __cxl_dpa_to_region(struct device *dev, void *arg)
+{
+	struct cxl_dpa_to_region_context *ctx = arg;
+	struct cxl_endpoint_decoder *cxled;
+	u64 dpa = ctx->dpa;
+
+	if (!is_endpoint_decoder(dev))
+		return 0;
+
+	cxled = to_cxl_endpoint_decoder(dev);
+	if (!cxled->dpa_res || !resource_size(cxled->dpa_res))
+		return 0;
+
+	if (dpa > cxled->dpa_res->end || dpa < cxled->dpa_res->start)
+		return 0;
+
+	dev_dbg(dev, "dpa:0x%llx mapped in region:%s\n", dpa,
+		dev_name(&cxled->cxld.region->dev));
+
+	ctx->cxlr = cxled->cxld.region;
+
+	return 1;
+}
+
+struct cxl_region *cxl_dpa_to_region(const struct cxl_memdev *cxlmd, u64 dpa)
+{
+	struct cxl_dpa_to_region_context ctx;
+	struct cxl_port *port;
+
+	ctx = (struct cxl_dpa_to_region_context) {
+		.dpa = dpa,
+	};
+	port = cxlmd->endpoint;
+	if (port && is_cxl_endpoint(port) && cxl_num_decoders_committed(port))
+		device_for_each_child(&port->dev, &ctx, __cxl_dpa_to_region);
+
+	return ctx.cxlr;
+}
+
 static struct lock_class_key cxl_pmem_region_key;
 
 static struct cxl_pmem_region *cxl_pmem_region_alloc(struct cxl_region *cxlr)