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4da08477ea
Naming the counter device provides a convenient way to identify it in devres_log events and similar situations. This patch names the counter device by combining the prefix "counter" with the counter device's unique ID. Link: https://lore.kernel.org/r/20220204084551.16397-1-vilhelm.gray@gmail.com Acked-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de> Signed-off-by: William Breathitt Gray <vilhelm.gray@gmail.com> Link: https://lore.kernel.org/r/87cc8eb4c84f49f89290577dc9231b2e4d7d3e8c.1647373009.git.vilhelm.gray@gmail.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
283 lines
6.2 KiB
C
283 lines
6.2 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Generic Counter interface
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* Copyright (C) 2020 William Breathitt Gray
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*/
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#include <linux/cdev.h>
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#include <linux/counter.h>
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#include <linux/device.h>
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#include <linux/device/bus.h>
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#include <linux/export.h>
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#include <linux/fs.h>
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#include <linux/gfp.h>
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#include <linux/idr.h>
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#include <linux/init.h>
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#include <linux/kdev_t.h>
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#include <linux/module.h>
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#include <linux/mutex.h>
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#include <linux/slab.h>
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#include <linux/types.h>
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#include <linux/wait.h>
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#include "counter-chrdev.h"
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#include "counter-sysfs.h"
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#define COUNTER_NAME "counter"
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/* Provides a unique ID for each counter device */
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static DEFINE_IDA(counter_ida);
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struct counter_device_allochelper {
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struct counter_device counter;
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/*
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* This is cache line aligned to ensure private data behaves like if it
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* were kmalloced separately.
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*/
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unsigned long privdata[] ____cacheline_aligned;
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};
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static void counter_device_release(struct device *dev)
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{
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struct counter_device *const counter =
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container_of(dev, struct counter_device, dev);
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counter_chrdev_remove(counter);
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ida_free(&counter_ida, dev->id);
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kfree(container_of(counter, struct counter_device_allochelper, counter));
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}
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static struct device_type counter_device_type = {
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.name = "counter_device",
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.release = counter_device_release,
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};
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static struct bus_type counter_bus_type = {
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.name = "counter",
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.dev_name = "counter",
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};
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static dev_t counter_devt;
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/**
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* counter_priv - access counter device private data
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* @counter: counter device
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*
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* Get the counter device private data
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*/
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void *counter_priv(const struct counter_device *const counter)
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{
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struct counter_device_allochelper *ch =
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container_of(counter, struct counter_device_allochelper, counter);
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return &ch->privdata;
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}
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EXPORT_SYMBOL_GPL(counter_priv);
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/**
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* counter_alloc - allocate a counter_device
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* @sizeof_priv: size of the driver private data
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*
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* This is part one of counter registration. The structure is allocated
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* dynamically to ensure the right lifetime for the embedded struct device.
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*
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* If this succeeds, call counter_put() to get rid of the counter_device again.
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*/
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struct counter_device *counter_alloc(size_t sizeof_priv)
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{
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struct counter_device_allochelper *ch;
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struct counter_device *counter;
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struct device *dev;
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int err;
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ch = kzalloc(sizeof(*ch) + sizeof_priv, GFP_KERNEL);
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if (!ch)
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return NULL;
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counter = &ch->counter;
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dev = &counter->dev;
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/* Acquire unique ID */
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err = ida_alloc(&counter_ida, GFP_KERNEL);
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if (err < 0)
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goto err_ida_alloc;
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dev->id = err;
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mutex_init(&counter->ops_exist_lock);
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dev->type = &counter_device_type;
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dev->bus = &counter_bus_type;
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dev->devt = MKDEV(MAJOR(counter_devt), dev->id);
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err = counter_chrdev_add(counter);
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if (err < 0)
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goto err_chrdev_add;
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device_initialize(dev);
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err = dev_set_name(dev, COUNTER_NAME "%d", dev->id);
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if (err)
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goto err_dev_set_name;
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return counter;
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err_dev_set_name:
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counter_chrdev_remove(counter);
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err_chrdev_add:
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ida_free(&counter_ida, dev->id);
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err_ida_alloc:
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kfree(ch);
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return NULL;
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}
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EXPORT_SYMBOL_GPL(counter_alloc);
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void counter_put(struct counter_device *counter)
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{
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put_device(&counter->dev);
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}
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EXPORT_SYMBOL_GPL(counter_put);
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/**
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* counter_add - complete registration of a counter
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* @counter: the counter to add
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*
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* This is part two of counter registration.
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*
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* If this succeeds, call counter_unregister() to get rid of the counter_device again.
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*/
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int counter_add(struct counter_device *counter)
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{
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int err;
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struct device *dev = &counter->dev;
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if (counter->parent) {
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dev->parent = counter->parent;
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dev->of_node = counter->parent->of_node;
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}
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err = counter_sysfs_add(counter);
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if (err < 0)
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return err;
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/* implies device_add(dev) */
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return cdev_device_add(&counter->chrdev, dev);
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}
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EXPORT_SYMBOL_GPL(counter_add);
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/**
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* counter_unregister - unregister Counter from the system
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* @counter: pointer to Counter to unregister
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*
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* The Counter is unregistered from the system.
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*/
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void counter_unregister(struct counter_device *const counter)
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{
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if (!counter)
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return;
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cdev_device_del(&counter->chrdev, &counter->dev);
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mutex_lock(&counter->ops_exist_lock);
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counter->ops = NULL;
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wake_up(&counter->events_wait);
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mutex_unlock(&counter->ops_exist_lock);
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}
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EXPORT_SYMBOL_GPL(counter_unregister);
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static void devm_counter_release(void *counter)
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{
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counter_unregister(counter);
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}
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static void devm_counter_put(void *counter)
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{
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counter_put(counter);
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}
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/**
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* devm_counter_alloc - allocate a counter_device
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* @dev: the device to register the release callback for
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* @sizeof_priv: size of the driver private data
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*
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* This is the device managed version of counter_add(). It registers a cleanup
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* callback to care for calling counter_put().
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*/
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struct counter_device *devm_counter_alloc(struct device *dev, size_t sizeof_priv)
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{
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struct counter_device *counter;
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int err;
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counter = counter_alloc(sizeof_priv);
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if (!counter)
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return NULL;
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err = devm_add_action_or_reset(dev, devm_counter_put, counter);
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if (err < 0)
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return NULL;
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return counter;
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}
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EXPORT_SYMBOL_GPL(devm_counter_alloc);
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/**
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* devm_counter_add - complete registration of a counter
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* @dev: the device to register the release callback for
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* @counter: the counter to add
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*
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* This is the device managed version of counter_add(). It registers a cleanup
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* callback to care for calling counter_unregister().
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*/
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int devm_counter_add(struct device *dev,
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struct counter_device *const counter)
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{
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int err;
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err = counter_add(counter);
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if (err < 0)
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return err;
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return devm_add_action_or_reset(dev, devm_counter_release, counter);
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}
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EXPORT_SYMBOL_GPL(devm_counter_add);
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#define COUNTER_DEV_MAX 256
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static int __init counter_init(void)
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{
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int err;
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err = bus_register(&counter_bus_type);
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if (err < 0)
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return err;
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err = alloc_chrdev_region(&counter_devt, 0, COUNTER_DEV_MAX,
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COUNTER_NAME);
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if (err < 0)
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goto err_unregister_bus;
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return 0;
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err_unregister_bus:
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bus_unregister(&counter_bus_type);
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return err;
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}
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static void __exit counter_exit(void)
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{
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unregister_chrdev_region(counter_devt, COUNTER_DEV_MAX);
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bus_unregister(&counter_bus_type);
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}
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subsys_initcall(counter_init);
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module_exit(counter_exit);
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MODULE_AUTHOR("William Breathitt Gray <vilhelm.gray@gmail.com>");
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MODULE_DESCRIPTION("Generic Counter interface");
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MODULE_LICENSE("GPL v2");
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