1 files changed, 142 insertions, 0 deletions
diff --git a/drivers/counter/counter-core.c b/drivers/counter/counter-core.c
new file mode 100644
index 000000000000..c533a6ff12cf
--- /dev/null
+++ b/drivers/counter/counter-core.c
@@ -0,0 +1,142 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Generic Counter interface
+ * Copyright (C) 2020 William Breathitt Gray
+ */
+#include <linux/counter.h>
+#include <linux/device.h>
+#include <linux/export.h>
+#include <linux/gfp.h>
+#include <linux/idr.h>
+#include <linux/init.h>
+#include <linux/module.h>
+
+#include "counter-sysfs.h"
+
+/* Provides a unique ID for each counter device */
+static DEFINE_IDA(counter_ida);
+
+static void counter_device_release(struct device *dev)
+{
+	ida_free(&counter_ida, dev->id);
+}
+
+static struct device_type counter_device_type = {
+	.name = "counter_device",
+	.release = counter_device_release,
+};
+
+static struct bus_type counter_bus_type = {
+	.name = "counter",
+	.dev_name = "counter",
+};
+
+/**
+ * counter_register - register Counter to the system
+ * @counter:	pointer to Counter to register
+ *
+ * This function registers a Counter to the system. A sysfs "counter" directory
+ * will be created and populated with sysfs attributes correlating with the
+ * Counter Signals, Synapses, and Counts respectively.
+ */
+int counter_register(struct counter_device *const counter)
+{
+	struct device *const dev = &counter->dev;
+	int id;
+	int err;
+
+	/* Acquire unique ID */
+	id = ida_alloc(&counter_ida, GFP_KERNEL);
+	if (id < 0)
+		return id;
+
+	/* Configure device structure for Counter */
+	dev->id = id;
+	dev->type = &counter_device_type;
+	dev->bus = &counter_bus_type;
+	if (counter->parent) {
+		dev->parent = counter->parent;
+		dev->of_node = counter->parent->of_node;
+	}
+	device_initialize(dev);
+	dev_set_drvdata(dev, counter);
+
+	/* Add Counter sysfs attributes */
+	err = counter_sysfs_add(counter);
+	if (err < 0)
+		goto err_free_id;
+
+	/* Add device to system */
+	err = device_add(dev);
+	if (err < 0)
+		goto err_free_id;
+
+	return 0;
+
+err_free_id:
+	put_device(dev);
+	return err;
+}
+EXPORT_SYMBOL_GPL(counter_register);
+
+/**
+ * counter_unregister - unregister Counter from the system
+ * @counter:	pointer to Counter to unregister
+ *
+ * The Counter is unregistered from the system.
+ */
+void counter_unregister(struct counter_device *const counter)
+{
+	if (!counter)
+		return;
+
+	device_unregister(&counter->dev);
+}
+EXPORT_SYMBOL_GPL(counter_unregister);
+
+static void devm_counter_release(void *counter)
+{
+	counter_unregister(counter);
+}
+
+/**
+ * devm_counter_register - Resource-managed counter_register
+ * @dev:	device to allocate counter_device for
+ * @counter:	pointer to Counter to register
+ *
+ * Managed counter_register. The Counter registered with this function is
+ * automatically unregistered on driver detach. This function calls
+ * counter_register internally. Refer to that function for more information.
+ *
+ * RETURNS:
+ * 0 on success, negative error number on failure.
+ */
+int devm_counter_register(struct device *dev,
+			  struct counter_device *const counter)
+{
+	int err;
+
+	err = counter_register(counter);
+	if (err < 0)
+		return err;
+
+	return devm_add_action_or_reset(dev, devm_counter_release, counter);
+}
+EXPORT_SYMBOL_GPL(devm_counter_register);
+
+static int __init counter_init(void)
+{
+	return bus_register(&counter_bus_type);
+}
+
+static void __exit counter_exit(void)
+{
+	bus_unregister(&counter_bus_type);
+}
+
+subsys_initcall(counter_init);
+module_exit(counter_exit);
+
+MODULE_AUTHOR("William Breathitt Gray <vilhelm.gray@gmail.com>");
+MODULE_DESCRIPTION("Generic Counter interface");
+MODULE_LICENSE("GPL v2");