[PATCH 1/3] fpga: bridge: make fpga_bridge_class a static const structure

[Ivan Orlov]

Now that the driver core allows for struct class to be in read-only
memory, move the fpga_bridge_class structure to be declared at build
time placing it into read-only memory, instead of having to be
dynamically allocated at boot time.

Suggested-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

Signed-off-by: Ivan Orlov <ivan.orlov0322@xxxxxxxxx>
---
 drivers/fpga/fpga-bridge.c | 106 ++++++++++++++++++-------------------
 1 file changed, 52 insertions(+), 54 deletions(-)

diff --git a/drivers/fpga/fpga-bridge.c b/drivers/fpga/fpga-bridge.c
index a6c25dee9cc1..6e38ddaf16cf 100644
--- a/drivers/fpga/fpga-bridge.c
+++ b/drivers/fpga/fpga-bridge.c
@@ -14,7 +14,6 @@
 #include <linux/spinlock.h>
 
 static DEFINE_IDA(fpga_bridge_ida);
-static struct class *fpga_bridge_class;
 
 /* Lock for adding/removing bridges to linked lists*/
 static DEFINE_SPINLOCK(bridge_list_lock);
@@ -84,6 +83,53 @@ static struct fpga_bridge *__fpga_bridge_get(struct device *dev,
 	return ERR_PTR(ret);
 }
 
+static ssize_t name_show(struct device *dev,
+			 struct device_attribute *attr, char *buf)
+{
+	struct fpga_bridge *bridge = to_fpga_bridge(dev);
+
+	return sprintf(buf, "%s\n", bridge->name);
+}
+
+static ssize_t state_show(struct device *dev,
+			  struct device_attribute *attr, char *buf)
+{
+	struct fpga_bridge *bridge = to_fpga_bridge(dev);
+	int state = 1;
+
+	if (bridge->br_ops && bridge->br_ops->enable_show) {
+		state = bridge->br_ops->enable_show(bridge);
+		if (state < 0)
+			return state;
+	}
+
+	return sysfs_emit(buf, "%s\n", state ? "enabled" : "disabled");
+}
+
+static DEVICE_ATTR_RO(name);
+static DEVICE_ATTR_RO(state);
+
+static struct attribute *fpga_bridge_attrs[] = {
+	&dev_attr_name.attr,
+	&dev_attr_state.attr,
+	NULL,
+};
+ATTRIBUTE_GROUPS(fpga_bridge);
+
+static void fpga_bridge_dev_release(struct device *dev)
+{
+	struct fpga_bridge *bridge = to_fpga_bridge(dev);
+
+	ida_free(&fpga_bridge_ida, bridge->dev.id);
+	kfree(bridge);
+}
+
+static const struct class fpga_bridge_class = {
+	.name = "fpga_bridge",
+	.dev_groups = fpga_bridge_groups,
+	.dev_release = fpga_bridge_dev_release,
+};
+
 /**
  * of_fpga_bridge_get - get an exclusive reference to an fpga bridge
  *
@@ -99,7 +145,7 @@ struct fpga_bridge *of_fpga_bridge_get(struct device_node *np,
 {
 	struct device *dev;
 
-	dev = class_find_device_by_of_node(fpga_bridge_class, np);
+	dev = class_find_device_by_of_node(&fpga_bridge_class, np);
 	if (!dev)
 		return ERR_PTR(-ENODEV);
 
@@ -126,7 +172,7 @@ struct fpga_bridge *fpga_bridge_get(struct device *dev,
 {
 	struct device *bridge_dev;
 
-	bridge_dev = class_find_device(fpga_bridge_class, NULL, dev,
+	bridge_dev = class_find_device(&fpga_bridge_class, NULL, dev,
 				       fpga_bridge_dev_match);
 	if (!bridge_dev)
 		return ERR_PTR(-ENODEV);
@@ -281,39 +327,6 @@ int fpga_bridge_get_to_list(struct device *dev,
 }
 EXPORT_SYMBOL_GPL(fpga_bridge_get_to_list);
 
-static ssize_t name_show(struct device *dev,
-			 struct device_attribute *attr, char *buf)
-{
-	struct fpga_bridge *bridge = to_fpga_bridge(dev);
-
-	return sprintf(buf, "%s\n", bridge->name);
-}
-
-static ssize_t state_show(struct device *dev,
-			  struct device_attribute *attr, char *buf)
-{
-	struct fpga_bridge *bridge = to_fpga_bridge(dev);
-	int state = 1;
-
-	if (bridge->br_ops && bridge->br_ops->enable_show) {
-		state = bridge->br_ops->enable_show(bridge);
-		if (state < 0)
-			return state;
-	}
-
-	return sysfs_emit(buf, "%s\n", state ? "enabled" : "disabled");
-}
-
-static DEVICE_ATTR_RO(name);
-static DEVICE_ATTR_RO(state);
-
-static struct attribute *fpga_bridge_attrs[] = {
-	&dev_attr_name.attr,
-	&dev_attr_state.attr,
-	NULL,
-};
-ATTRIBUTE_GROUPS(fpga_bridge);
-
 /**
  * fpga_bridge_register - create and register an FPGA Bridge device
  * @parent:	FPGA bridge device from pdev
@@ -359,7 +372,7 @@ fpga_bridge_register(struct device *parent, const char *name,
 	bridge->priv = priv;
 
 	bridge->dev.groups = br_ops->groups;
-	bridge->dev.class = fpga_bridge_class;
+	bridge->dev.class = &fpga_bridge_class;
 	bridge->dev.parent = parent;
 	bridge->dev.of_node = parent->of_node;
 	bridge->dev.id = id;
@@ -407,29 +420,14 @@ void fpga_bridge_unregister(struct fpga_bridge *bridge)
 }
 EXPORT_SYMBOL_GPL(fpga_bridge_unregister);
 
-static void fpga_bridge_dev_release(struct device *dev)
-{
-	struct fpga_bridge *bridge = to_fpga_bridge(dev);
-
-	ida_free(&fpga_bridge_ida, bridge->dev.id);
-	kfree(bridge);
-}
-
 static int __init fpga_bridge_dev_init(void)
 {
-	fpga_bridge_class = class_create("fpga_bridge");
-	if (IS_ERR(fpga_bridge_class))
-		return PTR_ERR(fpga_bridge_class);
-
-	fpga_bridge_class->dev_groups = fpga_bridge_groups;
-	fpga_bridge_class->dev_release = fpga_bridge_dev_release;
-
-	return 0;
+	return class_register(&fpga_bridge_class);
 }
 
 static void __exit fpga_bridge_dev_exit(void)
 {
-	class_destroy(fpga_bridge_class);
+	class_unregister(&fpga_bridge_class);
 	ida_destroy(&fpga_bridge_ida);
 }
 
-- 
2.34.1