firmware: rp1: Linger on firmware failure

To avoid pointless retries, let the probe function succeed if the
firmware interface is configured correctly but the firmware is
incompatible. The value of the private drvdata field holds the outcome.

Link: raspberrypi#6642

Signed-off-by: Phil Elwell <phil@raspberrypi.com>

Author: pelwell

drivers/firmware/rp1.c

@@ -157,7 +157,7 @@ struct rp1_firmware *rp1_firmware_get(struct device_node *client)
 	const char *match = rp1_firmware_of_match[0].compatible;
 	struct platform_device *pdev;
 	struct device_node *fwnode;
-	struct rp1_firmware *fw;
+	struct rp1_firmware *fw = NULL;
 
 	if (!client)
 		return NULL;
@@ -166,7 +166,7 @@ struct rp1_firmware *rp1_firmware_get(struct device_node *client)
 		return NULL;
 	if (!of_device_is_compatible(fwnode, match)) {
 		of_node_put(fwnode);
-		return NULL;
+		return ERR_PTR(-ENXIO);
 	}
 
 	pdev = of_find_device_by_node(fwnode);
@@ -176,7 +176,7 @@ struct rp1_firmware *rp1_firmware_get(struct device_node *client)
 		goto err_exit;
 
 	fw = platform_get_drvdata(pdev);
-	if (!fw)
+	if (IS_ERR_OR_NULL(fw))
 		goto err_exit;
 
 	if (!kref_get_unless_zero(&fw->consumers))
@@ -188,7 +188,7 @@ struct rp1_firmware *rp1_firmware_get(struct device_node *client)
 
 err_exit:
 	put_device(&pdev->dev);
-	return NULL;
+	return fw;
 }
 EXPORT_SYMBOL_GPL(rp1_firmware_get);
 
@@ -204,8 +204,8 @@ struct rp1_firmware *devm_rp1_firmware_get(struct device *dev, struct device_nod
 	int ret;
 
 	fw = rp1_firmware_get(client);
-	if (!fw)
-		return NULL;
+	if (IS_ERR_OR_NULL(fw))
+		return fw;
 
 	ret = devm_add_action_or_reset(dev, devm_rp1_firmware_put, fw);
 	if (ret)
@@ -270,19 +270,18 @@ static int rp1_firmware_probe(struct platform_device *pdev)
 	init_completion(&fw->c);
 	kref_init(&fw->consumers);
 
-	platform_set_drvdata(pdev, fw);
-
 	ret = rp1_firmware_message(fw, GET_FIRMWARE_VERSION,
 				   NULL, 0, &version, sizeof(version));
 	if (ret == sizeof(version)) {
 		dev_info(dev, "RP1 Firmware version %08x%08x%08x%08x%08x\n",
 			 version[0], version[1], version[2], version[3], version[4]);
-		ret = 0;
-	} else if (ret >= 0) {
-		ret = -EIO;
+		platform_set_drvdata(pdev, fw);
+	} else {
+		kfree(fw);
+		platform_set_drvdata(pdev, ERR_PTR(-ENOENT));
 	}
 
-	return ret;
+	return 0;
 }
 
 static int rp1_firmware_remove(struct platform_device *pdev)