spi/of: Create new device registration method and accessors

Dynamically inserting spi device nodes requires the use of a single
device registration method. Refactor the existing
of_register_spi_devices() to split out the core functionality for a
single device into a separate function; of_register_spi_device(). This
function will be used by the OF_DYNAMIC overlay code to make live
modifications to the tree.

Methods to lookup a device/master using a device node are added
as well, of_find_spi_master_by_node() & of_find_spi_device_by_node().
Signed-off-by: Pantelis Antoniou <pantelis.antoniou@konsulko.com>
[grant.likely] Split patch into two pieces for clarity
Signed-off-by: Grant Likely <grant.likely@linaro.org>
Reviewed-by: Mark Brown <broonie@kernel.org>
Cc: <linux-spi@vger.kernel.org>

drivers/spi/spi.c

@@ -1220,40 +1220,29 @@ static int spi_master_initialize_queue(struct spi_master *master)
 /*-------------------------------------------------------------------------*/
 
 #if defined(CONFIG_OF)
-/**
- * of_register_spi_devices() - Register child devices onto the SPI bus
- * @master:	Pointer to spi_master device
- *
- * Registers an spi_device for each child node of master node which has a 'reg'
- * property.
- */
-static void of_register_spi_devices(struct spi_master *master)
+static struct spi_device *
+of_register_spi_device(struct spi_master *master, struct device_node *nc)
 {
 	struct spi_device *spi;
-	struct device_node *nc;
 	int rc;
 	u32 value;
 
-	if (!master->dev.of_node)
-		return;
-
-	for_each_available_child_of_node(master->dev.of_node, nc) {
 	/* Alloc an spi_device */
 	spi = spi_alloc_device(master);
 	if (!spi) {
 		dev_err(&master->dev, "spi_device alloc error for %s\n",
 			nc->full_name);
-			spi_dev_put(spi);
-			continue;
+		rc = -ENOMEM;
+		goto err_out;
 	}
 
 	/* Select device driver */
-		if (of_modalias_node(nc, spi->modalias,
-				     sizeof(spi->modalias)) < 0) {
+	rc = of_modalias_node(nc, spi->modalias,
+				sizeof(spi->modalias));
+	if (rc < 0) {
 		dev_err(&master->dev, "cannot find modalias for %s\n",
 			nc->full_name);
-			spi_dev_put(spi);
-			continue;
+		goto err_out;
 	}
 
 	/* Device address */
@@ -1261,8 +1250,7 @@ static void of_register_spi_devices(struct spi_master *master)
 	if (rc) {
 		dev_err(&master->dev, "%s has no valid 'reg' property (%d)\n",
 			nc->full_name, rc);
-			spi_dev_put(spi);
-			continue;
+		goto err_out;
 	}
 	spi->chip_select = value;
 
@@ -1320,8 +1308,7 @@ static void of_register_spi_devices(struct spi_master *master)
 	if (rc) {
 		dev_err(&master->dev, "%s has no valid 'spi-max-frequency' property (%d)\n",
 			nc->full_name, rc);
-			spi_dev_put(spi);
-			continue;
+		goto err_out;
 	}
 	spi->max_speed_hz = value;
 
@@ -1338,9 +1325,36 @@ static void of_register_spi_devices(struct spi_master *master)
 	if (rc) {
 		dev_err(&master->dev, "spi_device register error %s\n",
 			nc->full_name);
-			spi_dev_put(spi);
+		goto err_out;
 	}
 
+	return spi;
+
+err_out:
+	spi_dev_put(spi);
+	return ERR_PTR(rc);
+}
+
+/**
+ * of_register_spi_devices() - Register child devices onto the SPI bus
+ * @master:	Pointer to spi_master device
+ *
+ * Registers an spi_device for each child node of master node which has a 'reg'
+ * property.
+ */
+static void of_register_spi_devices(struct spi_master *master)
+{
+	struct spi_device *spi;
+	struct device_node *nc;
+
+	if (!master->dev.of_node)
+		return;
+
+	for_each_available_child_of_node(master->dev.of_node, nc) {
+		spi = of_register_spi_device(master, nc);
+		if (IS_ERR(spi))
+			dev_warn(&master->dev, "Failed to create SPI device for %s\n",
+				nc->full_name);
 	}
 }
 #else