diff options
Diffstat (limited to 'drivers/counter/counter-core.c')
| -rw-r--r-- | drivers/counter/counter-core.c | 191 |
1 files changed, 191 insertions, 0 deletions
diff --git a/drivers/counter/counter-core.c b/drivers/counter/counter-core.c new file mode 100644 index 000000000000..5acc54539623 --- /dev/null +++ b/drivers/counter/counter-core.c @@ -0,0 +1,191 @@ +// 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"); |