1 files changed, 282 insertions, 0 deletions
diff --git a/drivers/counter/counter-core.c b/drivers/counter/counter-core.c
new file mode 100644
index 000000000..09c77afb3
--- /dev/null
+++ b/drivers/counter/counter-core.c
@@ -0,0 +1,282 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Generic Counter interface
+ * Copyright (C) 2020 William Breathitt Gray
+ */
+#include <linux/cdev.h>
+#include <linux/counter.h>
+#include <linux/device.h>
+#include <linux/device/bus.h>
+#include <linux/export.h>
+#include <linux/fs.h>
+#include <linux/gfp.h>
+#include <linux/idr.h>
+#include <linux/init.h>
+#include <linux/kdev_t.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/slab.h>
+#include <linux/types.h>
+#include <linux/wait.h>
+
+#include "counter-chrdev.h"
+#include "counter-sysfs.h"
+
+#define COUNTER_NAME	"counter"
+
+/* Provides a unique ID for each counter device */
+static DEFINE_IDA(counter_ida);
+
+struct counter_device_allochelper {
+	struct counter_device counter;
+
+	/*
+	 * This is cache line aligned to ensure private data behaves like if it
+	 * were kmalloced separately.
+	 */
+	unsigned long privdata[] ____cacheline_aligned;
+};
+
+static void counter_device_release(struct device *dev)
+{
+	struct counter_device *const counter =
+		container_of(dev, struct counter_device, dev);
+
+	counter_chrdev_remove(counter);
+	ida_free(&counter_ida, dev->id);
+
+	kfree(container_of(counter, struct counter_device_allochelper, counter));
+}
+
+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",
+};
+
+static dev_t counter_devt;
+
+/**
+ * counter_priv - access counter device private data
+ * @counter: counter device
+ *
+ * Get the counter device private data
+ */
+void *counter_priv(const struct counter_device *const counter)
+{
+	struct counter_device_allochelper *ch =
+		container_of(counter, struct counter_device_allochelper, counter);
+
+	return &ch->privdata;
+}
+EXPORT_SYMBOL_NS_GPL(counter_priv, COUNTER);
+
+/**
+ * counter_alloc - allocate a counter_device
+ * @sizeof_priv: size of the driver private data
+ *
+ * This is part one of counter registration. The structure is allocated
+ * dynamically to ensure the right lifetime for the embedded struct device.
+ *
+ * If this succeeds, call counter_put() to get rid of the counter_device again.
+ */
+struct counter_device *counter_alloc(size_t sizeof_priv)
+{
+	struct counter_device_allochelper *ch;
+	struct counter_device *counter;
+	struct device *dev;
+	int err;
+
+	ch = kzalloc(sizeof(*ch) + sizeof_priv, GFP_KERNEL);
+	if (!ch)
+		return NULL;
+
+	counter = &ch->counter;
+	dev = &counter->dev;
+
+	/* Acquire unique ID */
+	err = ida_alloc(&counter_ida, GFP_KERNEL);
+	if (err < 0)
+		goto err_ida_alloc;
+	dev->id = err;
+
+	mutex_init(&counter->ops_exist_lock);
+	dev->type = &counter_device_type;
+	dev->bus = &counter_bus_type;
+	dev->devt = MKDEV(MAJOR(counter_devt), dev->id);
+
+	err = counter_chrdev_add(counter);
+	if (err < 0)
+		goto err_chrdev_add;
+
+	device_initialize(dev);
+
+	err = dev_set_name(dev, COUNTER_NAME "%d", dev->id);
+	if (err)
+		goto err_dev_set_name;
+
+	return counter;
+
+err_dev_set_name:
+
+	counter_chrdev_remove(counter);
+err_chrdev_add:
+
+	ida_free(&counter_ida, dev->id);
+err_ida_alloc:
+
+	kfree(ch);
+
+	return NULL;
+}
+EXPORT_SYMBOL_NS_GPL(counter_alloc, COUNTER);
+
+void counter_put(struct counter_device *counter)
+{
+	put_device(&counter->dev);
+}
+EXPORT_SYMBOL_NS_GPL(counter_put, COUNTER);
+
+/**
+ * counter_add - complete registration of a counter
+ * @counter: the counter to add
+ *
+ * This is part two of counter registration.
+ *
+ * If this succeeds, call counter_unregister() to get rid of the counter_device again.
+ */
+int counter_add(struct counter_device *counter)
+{
+	int err;
+	struct device *dev = &counter->dev;
+
+	if (counter->parent) {
+		dev->parent = counter->parent;
+		dev->of_node = counter->parent->of_node;
+	}
+
+	err = counter_sysfs_add(counter);
+	if (err < 0)
+		return err;
+
+	/* implies device_add(dev) */
+	return cdev_device_add(&counter->chrdev, dev);
+}
+EXPORT_SYMBOL_NS_GPL(counter_add, COUNTER);
+
+/**
+ * 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;
+
+	cdev_device_del(&counter->chrdev, &counter->dev);
+
+	mutex_lock(&counter->ops_exist_lock);
+
+	counter->ops = NULL;
+	wake_up(&counter->events_wait);
+
+	mutex_unlock(&counter->ops_exist_lock);
+}
+EXPORT_SYMBOL_NS_GPL(counter_unregister, COUNTER);
+
+static void devm_counter_release(void *counter)
+{
+	counter_unregister(counter);
+}
+
+static void devm_counter_put(void *counter)
+{
+	counter_put(counter);
+}
+
+/**
+ * devm_counter_alloc - allocate a counter_device
+ * @dev: the device to register the release callback for
+ * @sizeof_priv: size of the driver private data
+ *
+ * This is the device managed version of counter_add(). It registers a cleanup
+ * callback to care for calling counter_put().
+ */
+struct counter_device *devm_counter_alloc(struct device *dev, size_t sizeof_priv)
+{
+	struct counter_device *counter;
+	int err;
+
+	counter = counter_alloc(sizeof_priv);
+	if (!counter)
+		return NULL;
+
+	err = devm_add_action_or_reset(dev, devm_counter_put, counter);
+	if (err < 0)
+		return NULL;
+
+	return counter;
+}
+EXPORT_SYMBOL_NS_GPL(devm_counter_alloc, COUNTER);
+
+/**
+ * devm_counter_add - complete registration of a counter
+ * @dev: the device to register the release callback for
+ * @counter: the counter to add
+ *
+ * This is the device managed version of counter_add(). It registers a cleanup
+ * callback to care for calling counter_unregister().
+ */
+int devm_counter_add(struct device *dev,
+		     struct counter_device *const counter)
+{
+	int err;
+
+	err = counter_add(counter);
+	if (err < 0)
+		return err;
+
+	return devm_add_action_or_reset(dev, devm_counter_release, counter);
+}
+EXPORT_SYMBOL_NS_GPL(devm_counter_add, COUNTER);
+
+#define COUNTER_DEV_MAX 256
+
+static int __init counter_init(void)
+{
+	int err;
+
+	err = bus_register(&counter_bus_type);
+	if (err < 0)
+		return err;
+
+	err = alloc_chrdev_region(&counter_devt, 0, COUNTER_DEV_MAX,
+				  COUNTER_NAME);
+	if (err < 0)
+		goto err_unregister_bus;
+
+	return 0;
+
+err_unregister_bus:
+	bus_unregister(&counter_bus_type);
+	return err;
+}
+
+static void __exit counter_exit(void)
+{
+	unregister_chrdev_region(counter_devt, COUNTER_DEV_MAX);
+	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");