cxl: Add cxl_decoders_committed() helper

Add a helper to retrieve the number of decoders committed for the port.
Replace all the open coding of the calculation with the helper.

Link: https://lore.kernel.org/linux-cxl/651c98472dfed_ae7e729495@dwillia2-xfh.jf.intel.com.notmuch/Suggested-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Jim Harris <jim.harris@samsung.com>
Reviewed-by: Alison Schofield <alison.schofield@intel.com>
Link: https://lore.kernel.org/r/169747906849.272156.1729290904857372335.stgit@djiang5-mobl3Signed-off-by: Dan Williams <dan.j.williams@intel.com>

drivers/cxl/core/hdm.c

@@ -643,10 +643,11 @@ static int cxl_decoder_commit(struct cxl_decoder *cxld)
 	if (cxld->flags & CXL_DECODER_F_ENABLE)
 		return 0;
 
-	if (port->commit_end + 1 != id) {
+	if (cxl_num_decoders_committed(port) != id) {
 		dev_dbg(&port->dev,
 			"%s: out of order commit, expected decoder%d.%d\n",
-			dev_name(&cxld->dev), port->id, port->commit_end + 1);
+			dev_name(&cxld->dev), port->id,
+			cxl_num_decoders_committed(port));
 		return -EBUSY;
 	}
 
@@ -863,7 +864,7 @@ static int init_hdm_decoder(struct cxl_port *port, struct cxl_decoder *cxld,
 			cxld->target_type = CXL_DECODER_HOSTONLYMEM;
 		else
 			cxld->target_type = CXL_DECODER_DEVMEM;
-		if (cxld->id != port->commit_end + 1) {
+		if (cxld->id != cxl_num_decoders_committed(port)) {
 			dev_warn(&port->dev,
 				 "decoder%d.%d: Committed out of order\n",
 				 port->id, cxld->id);

drivers/cxl/core/mbox.c

@@ -1200,7 +1200,7 @@ int cxl_mem_sanitize(struct cxl_memdev *cxlmd, u16 cmd)
 	 * Require an endpoint to be safe otherwise the driver can not
 	 * be sure that the device is unmapped.
 	 */
-	if (endpoint && endpoint->commit_end == -1)
+	if (endpoint && cxl_num_decoders_committed(endpoint) == 0)
 		rc = __cxl_mem_sanitize(mds, cmd);
 	else
 		rc = -EBUSY;

drivers/cxl/core/memdev.c

@@ -231,7 +231,7 @@ int cxl_trigger_poison_list(struct cxl_memdev *cxlmd)
 	if (rc)
 		return rc;
 
-	if (port->commit_end == -1) {
+	if (cxl_num_decoders_committed(port) == 0) {
 		/* No regions mapped to this memdev */
 		rc = cxl_get_poison_by_memdev(cxlmd);
 	} else {
@@ -282,7 +282,7 @@ static struct cxl_region *cxl_dpa_to_region(struct cxl_memdev *cxlmd, u64 dpa)
 		.dpa = dpa,
 	};
 	port = cxlmd->endpoint;
-	if (port && is_cxl_endpoint(port) && port->commit_end != -1)
+	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;

drivers/cxl/core/port.c

@@ -37,6 +37,13 @@ DECLARE_RWSEM(cxl_region_rwsem);
 static DEFINE_IDA(cxl_port_ida);
 static DEFINE_XARRAY(cxl_root_buses);
 
+int cxl_num_decoders_committed(struct cxl_port *port)
+{
+	lockdep_assert_held(&cxl_region_rwsem);
+
+	return port->commit_end + 1;
+}
+
 static ssize_t devtype_show(struct device *dev, struct device_attribute *attr,
 			    char *buf)
 {

drivers/cxl/cxl.h

@@ -679,6 +679,7 @@ static inline bool is_cxl_root(struct cxl_port *port)
 	return port->uport_dev == port->dev.parent;
 }
 
+int cxl_num_decoders_committed(struct cxl_port *port);
 bool is_cxl_port(const struct device *dev);
 struct cxl_port *to_cxl_port(const struct device *dev);
 struct pci_bus;