blob: 869894b747413cf1d37907ba61ae59215cf2b878 [file] [log] [blame]
William Breathitt Grayaaec1a02021-08-27 12:47:47 +09001// SPDX-License-Identifier: GPL-2.0
2/*
3 * Generic Counter interface
4 * Copyright (C) 2020 William Breathitt Gray
5 */
William Breathitt Grayb6c50af2021-09-29 12:15:59 +09006#include <linux/cdev.h>
William Breathitt Grayaaec1a02021-08-27 12:47:47 +09007#include <linux/counter.h>
8#include <linux/device.h>
William Breathitt Grayb6c50af2021-09-29 12:15:59 +09009#include <linux/device/bus.h>
William Breathitt Grayaaec1a02021-08-27 12:47:47 +090010#include <linux/export.h>
William Breathitt Grayb6c50af2021-09-29 12:15:59 +090011#include <linux/fs.h>
William Breathitt Grayaaec1a02021-08-27 12:47:47 +090012#include <linux/gfp.h>
13#include <linux/idr.h>
14#include <linux/init.h>
William Breathitt Grayb6c50af2021-09-29 12:15:59 +090015#include <linux/kdev_t.h>
William Breathitt Grayaaec1a02021-08-27 12:47:47 +090016#include <linux/module.h>
William Breathitt Grayb6c50af2021-09-29 12:15:59 +090017#include <linux/mutex.h>
Uwe Kleine-Königc18e2762021-12-30 16:02:50 +010018#include <linux/slab.h>
William Breathitt Grayb6c50af2021-09-29 12:15:59 +090019#include <linux/types.h>
20#include <linux/wait.h>
William Breathitt Grayaaec1a02021-08-27 12:47:47 +090021
William Breathitt Grayb6c50af2021-09-29 12:15:59 +090022#include "counter-chrdev.h"
William Breathitt Grayaaec1a02021-08-27 12:47:47 +090023#include "counter-sysfs.h"
24
25/* Provides a unique ID for each counter device */
26static DEFINE_IDA(counter_ida);
27
Uwe Kleine-Königc18e2762021-12-30 16:02:50 +010028struct counter_device_allochelper {
29 struct counter_device counter;
30
31 /*
32 * This is cache line aligned to ensure private data behaves like if it
33 * were kmalloced separately.
34 */
35 unsigned long privdata[] ____cacheline_aligned;
36};
37
William Breathitt Grayaaec1a02021-08-27 12:47:47 +090038static void counter_device_release(struct device *dev)
39{
Uwe Kleine-Königb56346d2021-12-30 16:02:38 +010040 struct counter_device *const counter =
41 container_of(dev, struct counter_device, dev);
William Breathitt Grayb6c50af2021-09-29 12:15:59 +090042
43 counter_chrdev_remove(counter);
William Breathitt Grayaaec1a02021-08-27 12:47:47 +090044 ida_free(&counter_ida, dev->id);
Uwe Kleine-Königc18e2762021-12-30 16:02:50 +010045
Uwe Kleine-Königf2ee4752021-12-30 16:03:00 +010046 kfree(container_of(counter, struct counter_device_allochelper, counter));
William Breathitt Grayaaec1a02021-08-27 12:47:47 +090047}
48
49static struct device_type counter_device_type = {
50 .name = "counter_device",
51 .release = counter_device_release,
52};
53
54static struct bus_type counter_bus_type = {
55 .name = "counter",
56 .dev_name = "counter",
57};
58
William Breathitt Grayb6c50af2021-09-29 12:15:59 +090059static dev_t counter_devt;
60
William Breathitt Grayaaec1a02021-08-27 12:47:47 +090061/**
Uwe Kleine-König5207fb22021-12-30 16:02:41 +010062 * counter_priv - access counter device private data
63 * @counter: counter device
64 *
65 * Get the counter device private data
66 */
67void *counter_priv(const struct counter_device *const counter)
68{
Uwe Kleine-Königf2ee4752021-12-30 16:03:00 +010069 struct counter_device_allochelper *ch =
70 container_of(counter, struct counter_device_allochelper, counter);
Uwe Kleine-Königc18e2762021-12-30 16:02:50 +010071
Uwe Kleine-Königf2ee4752021-12-30 16:03:00 +010072 return &ch->privdata;
Uwe Kleine-König5207fb22021-12-30 16:02:41 +010073}
74EXPORT_SYMBOL_GPL(counter_priv);
75
76/**
Uwe Kleine-Königc18e2762021-12-30 16:02:50 +010077 * counter_alloc - allocate a counter_device
78 * @sizeof_priv: size of the driver private data
79 *
80 * This is part one of counter registration. The structure is allocated
81 * dynamically to ensure the right lifetime for the embedded struct device.
82 *
83 * If this succeeds, call counter_put() to get rid of the counter_device again.
84 */
85struct counter_device *counter_alloc(size_t sizeof_priv)
86{
87 struct counter_device_allochelper *ch;
88 struct counter_device *counter;
89 struct device *dev;
90 int err;
91
92 ch = kzalloc(sizeof(*ch) + sizeof_priv, GFP_KERNEL);
Dan Carpenterfc55e632022-01-11 20:32:43 +030093 if (!ch)
94 return NULL;
Uwe Kleine-Königc18e2762021-12-30 16:02:50 +010095
96 counter = &ch->counter;
97 dev = &counter->dev;
98
99 /* Acquire unique ID */
100 err = ida_alloc(&counter_ida, GFP_KERNEL);
101 if (err < 0)
102 goto err_ida_alloc;
103 dev->id = err;
104
105 mutex_init(&counter->ops_exist_lock);
106 dev->type = &counter_device_type;
107 dev->bus = &counter_bus_type;
108 dev->devt = MKDEV(MAJOR(counter_devt), dev->id);
109
110 err = counter_chrdev_add(counter);
111 if (err < 0)
112 goto err_chrdev_add;
113
114 device_initialize(dev);
115
116 return counter;
117
118err_chrdev_add:
119
120 ida_free(&counter_ida, dev->id);
121err_ida_alloc:
122
123 kfree(ch);
Uwe Kleine-Königc18e2762021-12-30 16:02:50 +0100124
Dan Carpenterfc55e632022-01-11 20:32:43 +0300125 return NULL;
Uwe Kleine-Königc18e2762021-12-30 16:02:50 +0100126}
127EXPORT_SYMBOL_GPL(counter_alloc);
128
129void counter_put(struct counter_device *counter)
130{
131 put_device(&counter->dev);
132}
133EXPORT_SYMBOL_GPL(counter_put);
134
135/**
136 * counter_add - complete registration of a counter
137 * @counter: the counter to add
138 *
139 * This is part two of counter registration.
140 *
141 * If this succeeds, call counter_unregister() to get rid of the counter_device again.
142 */
143int counter_add(struct counter_device *counter)
144{
145 int err;
146 struct device *dev = &counter->dev;
147
148 if (counter->parent) {
149 dev->parent = counter->parent;
150 dev->of_node = counter->parent->of_node;
151 }
152
153 err = counter_sysfs_add(counter);
154 if (err < 0)
155 return err;
156
157 /* implies device_add(dev) */
158 return cdev_device_add(&counter->chrdev, dev);
159}
160EXPORT_SYMBOL_GPL(counter_add);
161
162/**
William Breathitt Grayaaec1a02021-08-27 12:47:47 +0900163 * counter_unregister - unregister Counter from the system
164 * @counter: pointer to Counter to unregister
165 *
166 * The Counter is unregistered from the system.
167 */
168void counter_unregister(struct counter_device *const counter)
169{
170 if (!counter)
171 return;
172
William Breathitt Grayb6c50af2021-09-29 12:15:59 +0900173 cdev_device_del(&counter->chrdev, &counter->dev);
174
175 mutex_lock(&counter->ops_exist_lock);
176
177 counter->ops = NULL;
178 wake_up(&counter->events_wait);
179
180 mutex_unlock(&counter->ops_exist_lock);
William Breathitt Grayaaec1a02021-08-27 12:47:47 +0900181}
182EXPORT_SYMBOL_GPL(counter_unregister);
183
184static void devm_counter_release(void *counter)
185{
186 counter_unregister(counter);
187}
188
Uwe Kleine-Königc18e2762021-12-30 16:02:50 +0100189static void devm_counter_put(void *counter)
190{
191 counter_put(counter);
192}
193
194/**
195 * devm_counter_alloc - allocate a counter_device
196 * @dev: the device to register the release callback for
197 * @sizeof_priv: size of the driver private data
198 *
199 * This is the device managed version of counter_add(). It registers a cleanup
200 * callback to care for calling counter_put().
201 */
202struct counter_device *devm_counter_alloc(struct device *dev, size_t sizeof_priv)
203{
204 struct counter_device *counter;
205 int err;
206
207 counter = counter_alloc(sizeof_priv);
Dan Carpenterfc55e632022-01-11 20:32:43 +0300208 if (!counter)
209 return NULL;
Uwe Kleine-Königc18e2762021-12-30 16:02:50 +0100210
211 err = devm_add_action_or_reset(dev, devm_counter_put, counter);
212 if (err < 0)
Dan Carpenterfc55e632022-01-11 20:32:43 +0300213 return NULL;
Uwe Kleine-Königc18e2762021-12-30 16:02:50 +0100214
215 return counter;
216}
217EXPORT_SYMBOL_GPL(devm_counter_alloc);
218
219/**
220 * devm_counter_add - complete registration of a counter
221 * @dev: the device to register the release callback for
222 * @counter: the counter to add
223 *
224 * This is the device managed version of counter_add(). It registers a cleanup
225 * callback to care for calling counter_unregister().
226 */
227int devm_counter_add(struct device *dev,
228 struct counter_device *const counter)
229{
230 int err;
231
232 err = counter_add(counter);
233 if (err < 0)
234 return err;
235
236 return devm_add_action_or_reset(dev, devm_counter_release, counter);
237}
238EXPORT_SYMBOL_GPL(devm_counter_add);
239
William Breathitt Grayb6c50af2021-09-29 12:15:59 +0900240#define COUNTER_DEV_MAX 256
241
William Breathitt Grayaaec1a02021-08-27 12:47:47 +0900242static int __init counter_init(void)
243{
William Breathitt Grayb6c50af2021-09-29 12:15:59 +0900244 int err;
245
246 err = bus_register(&counter_bus_type);
247 if (err < 0)
248 return err;
249
250 err = alloc_chrdev_region(&counter_devt, 0, COUNTER_DEV_MAX, "counter");
251 if (err < 0)
252 goto err_unregister_bus;
253
254 return 0;
255
256err_unregister_bus:
257 bus_unregister(&counter_bus_type);
258 return err;
William Breathitt Grayaaec1a02021-08-27 12:47:47 +0900259}
260
261static void __exit counter_exit(void)
262{
William Breathitt Grayb6c50af2021-09-29 12:15:59 +0900263 unregister_chrdev_region(counter_devt, COUNTER_DEV_MAX);
William Breathitt Grayaaec1a02021-08-27 12:47:47 +0900264 bus_unregister(&counter_bus_type);
265}
266
267subsys_initcall(counter_init);
268module_exit(counter_exit);
269
270MODULE_AUTHOR("William Breathitt Gray <vilhelm.gray@gmail.com>");
271MODULE_DESCRIPTION("Generic Counter interface");
272MODULE_LICENSE("GPL v2");