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// 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/types.h>
#include <linux/wait.h>
#include "counter-chrdev.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)
{
struct counter_device *const counter = dev_get_drvdata(dev);
counter_chrdev_remove(counter);
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",
};
static dev_t counter_devt;
/**
* 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.
*
* RETURNS:
* 0 on success, negative error number on failure.
*/
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;
mutex_init(&counter->ops_exist_lock);
/* Configure device structure for Counter */
dev->id = id;
dev->type = &counter_device_type;
dev->bus = &counter_bus_type;
dev->devt = MKDEV(MAJOR(counter_devt), id);
if (counter->parent) {
dev->parent = counter->parent;
dev->of_node = counter->parent->of_node;
}
device_initialize(dev);
dev_set_drvdata(dev, counter);
err = counter_sysfs_add(counter);
if (err < 0)
goto err_free_id;
err = counter_chrdev_add(counter);
if (err < 0)
goto err_free_id;
err = cdev_device_add(&counter->chrdev, dev);
if (err < 0)
goto err_remove_chrdev;
return 0;
err_remove_chrdev:
counter_chrdev_remove(counter);
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;
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);
put_device(&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);
#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");
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");
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