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1// SPDX-License-Identifier: GPL-2.0-or-later2/*3 * Roccat driver for Linux4 *5 * Copyright (c) 2010 Stefan Achatz <erazor_de@users.sourceforge.net>6 */7 8/*9 */10 11/*12 * Module roccat is a char device used to report special events of roccat13 * hardware to userland. These events include requests for on-screen-display of14 * profile or dpi settings or requests for execution of macro sequences that are15 * not stored in device. The information in these events depends on hid device16 * implementation and contains data that is not available in a single hid event17 * or else hidraw could have been used.18 * It is inspired by hidraw, but uses only one circular buffer for all readers.19 */20 21#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt22 23#include <linux/cdev.h>24#include <linux/poll.h>25#include <linux/sched/signal.h>26#include <linux/hid-roccat.h>27#include <linux/module.h>28 29#define ROCCAT_FIRST_MINOR 030#define ROCCAT_MAX_DEVICES 831 32/* should be a power of 2 for performance reason */33#define ROCCAT_CBUF_SIZE 1634 35struct roccat_report {36 uint8_t *value;37};38 39struct roccat_device {40 unsigned int minor;41 int report_size;42 int open;43 int exist;44 wait_queue_head_t wait;45 struct device *dev;46 struct hid_device *hid;47 struct list_head readers;48 /* protects modifications of readers list */49 struct mutex readers_lock;50 51 /*52 * circular_buffer has one writer and multiple readers with their own53 * read pointers54 */55 struct roccat_report cbuf[ROCCAT_CBUF_SIZE];56 int cbuf_end;57 struct mutex cbuf_lock;58};59 60struct roccat_reader {61 struct list_head node;62 struct roccat_device *device;63 int cbuf_start;64};65 66static int roccat_major;67static struct cdev roccat_cdev;68 69static struct roccat_device *devices[ROCCAT_MAX_DEVICES];70/* protects modifications of devices array */71static DEFINE_MUTEX(devices_lock);72 73static ssize_t roccat_read(struct file *file, char __user *buffer,74 size_t count, loff_t *ppos)75{76 struct roccat_reader *reader = file->private_data;77 struct roccat_device *device = reader->device;78 struct roccat_report *report;79 ssize_t retval = 0, len;80 DECLARE_WAITQUEUE(wait, current);81 82 mutex_lock(&device->cbuf_lock);83 84 /* no data? */85 if (reader->cbuf_start == device->cbuf_end) {86 add_wait_queue(&device->wait, &wait);87 set_current_state(TASK_INTERRUPTIBLE);88 89 /* wait for data */90 while (reader->cbuf_start == device->cbuf_end) {91 if (file->f_flags & O_NONBLOCK) {92 retval = -EAGAIN;93 break;94 }95 if (signal_pending(current)) {96 retval = -ERESTARTSYS;97 break;98 }99 if (!device->exist) {100 retval = -EIO;101 break;102 }103 104 mutex_unlock(&device->cbuf_lock);105 schedule();106 mutex_lock(&device->cbuf_lock);107 set_current_state(TASK_INTERRUPTIBLE);108 }109 110 set_current_state(TASK_RUNNING);111 remove_wait_queue(&device->wait, &wait);112 }113 114 /* here we either have data or a reason to return if retval is set */115 if (retval)116 goto exit_unlock;117 118 report = &device->cbuf[reader->cbuf_start];119 /*120 * If report is larger than requested amount of data, rest of report121 * is lost!122 */123 len = device->report_size > count ? count : device->report_size;124 125 if (copy_to_user(buffer, report->value, len)) {126 retval = -EFAULT;127 goto exit_unlock;128 }129 retval += len;130 reader->cbuf_start = (reader->cbuf_start + 1) % ROCCAT_CBUF_SIZE;131 132exit_unlock:133 mutex_unlock(&device->cbuf_lock);134 return retval;135}136 137static __poll_t roccat_poll(struct file *file, poll_table *wait)138{139 struct roccat_reader *reader = file->private_data;140 poll_wait(file, &reader->device->wait, wait);141 if (reader->cbuf_start != reader->device->cbuf_end)142 return EPOLLIN | EPOLLRDNORM;143 if (!reader->device->exist)144 return EPOLLERR | EPOLLHUP;145 return 0;146}147 148static int roccat_open(struct inode *inode, struct file *file)149{150 unsigned int minor = iminor(inode);151 struct roccat_reader *reader;152 struct roccat_device *device;153 int error = 0;154 155 reader = kzalloc(sizeof(struct roccat_reader), GFP_KERNEL);156 if (!reader)157 return -ENOMEM;158 159 mutex_lock(&devices_lock);160 161 device = devices[minor];162 163 if (!device) {164 pr_emerg("roccat device with minor %d doesn't exist\n", minor);165 error = -ENODEV;166 goto exit_err_devices;167 }168 169 mutex_lock(&device->readers_lock);170 171 if (!device->open++) {172 /* power on device on adding first reader */173 error = hid_hw_power(device->hid, PM_HINT_FULLON);174 if (error < 0) {175 --device->open;176 goto exit_err_readers;177 }178 179 error = hid_hw_open(device->hid);180 if (error < 0) {181 hid_hw_power(device->hid, PM_HINT_NORMAL);182 --device->open;183 goto exit_err_readers;184 }185 }186 187 reader->device = device;188 /* new reader doesn't get old events */189 reader->cbuf_start = device->cbuf_end;190 191 list_add_tail(&reader->node, &device->readers);192 file->private_data = reader;193 194exit_err_readers:195 mutex_unlock(&device->readers_lock);196exit_err_devices:197 mutex_unlock(&devices_lock);198 if (error)199 kfree(reader);200 return error;201}202 203static int roccat_release(struct inode *inode, struct file *file)204{205 unsigned int minor = iminor(inode);206 struct roccat_reader *reader = file->private_data;207 struct roccat_device *device;208 209 mutex_lock(&devices_lock);210 211 device = devices[minor];212 if (!device) {213 mutex_unlock(&devices_lock);214 pr_emerg("roccat device with minor %d doesn't exist\n", minor);215 return -ENODEV;216 }217 218 mutex_lock(&device->readers_lock);219 list_del(&reader->node);220 mutex_unlock(&device->readers_lock);221 kfree(reader);222 223 if (!--device->open) {224 /* removing last reader */225 if (device->exist) {226 hid_hw_power(device->hid, PM_HINT_NORMAL);227 hid_hw_close(device->hid);228 } else {229 kfree(device);230 }231 }232 233 mutex_unlock(&devices_lock);234 235 return 0;236}237 238/*239 * roccat_report_event() - output data to readers240 * @minor: minor device number returned by roccat_connect()241 * @data: pointer to data242 *243 * Return value is zero on success, a negative error code on failure.244 *245 * This is called from interrupt handler.246 */247int roccat_report_event(int minor, u8 const *data)248{249 struct roccat_device *device;250 struct roccat_reader *reader;251 struct roccat_report *report;252 uint8_t *new_value;253 254 device = devices[minor];255 256 new_value = kmemdup(data, device->report_size, GFP_ATOMIC);257 if (!new_value)258 return -ENOMEM;259 260 mutex_lock(&device->cbuf_lock);261 262 report = &device->cbuf[device->cbuf_end];263 264 /* passing NULL is safe */265 kfree(report->value);266 267 report->value = new_value;268 device->cbuf_end = (device->cbuf_end + 1) % ROCCAT_CBUF_SIZE;269 270 list_for_each_entry(reader, &device->readers, node) {271 /*272 * As we already inserted one element, the buffer can't be273 * empty. If start and end are equal, buffer is full and we274 * increase start, so that slow reader misses one event, but275 * gets the newer ones in the right order.276 */277 if (reader->cbuf_start == device->cbuf_end)278 reader->cbuf_start = (reader->cbuf_start + 1) % ROCCAT_CBUF_SIZE;279 }280 281 mutex_unlock(&device->cbuf_lock);282 283 wake_up_interruptible(&device->wait);284 return 0;285}286EXPORT_SYMBOL_GPL(roccat_report_event);287 288/*289 * roccat_connect() - create a char device for special event output290 * @class: the class thats used to create the device. Meant to hold device291 * specific sysfs attributes.292 * @hid: the hid device the char device should be connected to.293 * @report_size: size of reports294 *295 * Return value is minor device number in Range [0, ROCCAT_MAX_DEVICES] on296 * success, a negative error code on failure.297 */298int roccat_connect(const struct class *klass, struct hid_device *hid, int report_size)299{300 unsigned int minor;301 struct roccat_device *device;302 int temp;303 304 device = kzalloc(sizeof(struct roccat_device), GFP_KERNEL);305 if (!device)306 return -ENOMEM;307 308 mutex_lock(&devices_lock);309 310 for (minor = 0; minor < ROCCAT_MAX_DEVICES; ++minor) {311 if (devices[minor])312 continue;313 break;314 }315 316 if (minor < ROCCAT_MAX_DEVICES) {317 devices[minor] = device;318 } else {319 mutex_unlock(&devices_lock);320 kfree(device);321 return -EINVAL;322 }323 324 device->dev = device_create(klass, &hid->dev,325 MKDEV(roccat_major, minor), NULL,326 "%s%s%d", "roccat", hid->driver->name, minor);327 328 if (IS_ERR(device->dev)) {329 devices[minor] = NULL;330 mutex_unlock(&devices_lock);331 temp = PTR_ERR(device->dev);332 kfree(device);333 return temp;334 }335 336 mutex_unlock(&devices_lock);337 338 init_waitqueue_head(&device->wait);339 INIT_LIST_HEAD(&device->readers);340 mutex_init(&device->readers_lock);341 mutex_init(&device->cbuf_lock);342 device->minor = minor;343 device->hid = hid;344 device->exist = 1;345 device->cbuf_end = 0;346 device->report_size = report_size;347 348 return minor;349}350EXPORT_SYMBOL_GPL(roccat_connect);351 352/* roccat_disconnect() - remove char device from hid device353 * @minor: the minor device number returned by roccat_connect()354 */355void roccat_disconnect(int minor)356{357 struct roccat_device *device;358 359 mutex_lock(&devices_lock);360 device = devices[minor];361 mutex_unlock(&devices_lock);362 363 device->exist = 0; /* TODO exist maybe not needed */364 365 device_destroy(device->dev->class, MKDEV(roccat_major, minor));366 367 mutex_lock(&devices_lock);368 devices[minor] = NULL;369 mutex_unlock(&devices_lock);370 371 if (device->open) {372 hid_hw_close(device->hid);373 wake_up_interruptible(&device->wait);374 } else {375 kfree(device);376 }377}378EXPORT_SYMBOL_GPL(roccat_disconnect);379 380static long roccat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)381{382 struct inode *inode = file_inode(file);383 struct roccat_device *device;384 unsigned int minor = iminor(inode);385 long retval = 0;386 387 mutex_lock(&devices_lock);388 389 device = devices[minor];390 if (!device) {391 retval = -ENODEV;392 goto out;393 }394 395 switch (cmd) {396 case ROCCATIOCGREPSIZE:397 if (put_user(device->report_size, (int __user *)arg))398 retval = -EFAULT;399 break;400 default:401 retval = -ENOTTY;402 }403out:404 mutex_unlock(&devices_lock);405 return retval;406}407 408static const struct file_operations roccat_ops = {409 .owner = THIS_MODULE,410 .read = roccat_read,411 .poll = roccat_poll,412 .open = roccat_open,413 .release = roccat_release,414 .llseek = noop_llseek,415 .unlocked_ioctl = roccat_ioctl,416};417 418static int __init roccat_init(void)419{420 int retval;421 dev_t dev_id;422 423 retval = alloc_chrdev_region(&dev_id, ROCCAT_FIRST_MINOR,424 ROCCAT_MAX_DEVICES, "roccat");425 if (retval < 0) {426 pr_warn("can't get major number\n");427 goto error;428 }429 430 roccat_major = MAJOR(dev_id);431 432 cdev_init(&roccat_cdev, &roccat_ops);433 retval = cdev_add(&roccat_cdev, dev_id, ROCCAT_MAX_DEVICES);434 435 if (retval < 0) {436 pr_warn("cannot add cdev\n");437 goto cleanup_alloc_chrdev_region;438 }439 return 0;440 441 442 cleanup_alloc_chrdev_region:443 unregister_chrdev_region(dev_id, ROCCAT_MAX_DEVICES);444 error:445 return retval;446}447 448static void __exit roccat_exit(void)449{450 dev_t dev_id = MKDEV(roccat_major, 0);451 452 cdev_del(&roccat_cdev);453 unregister_chrdev_region(dev_id, ROCCAT_MAX_DEVICES);454}455 456module_init(roccat_init);457module_exit(roccat_exit);458 459MODULE_AUTHOR("Stefan Achatz");460MODULE_DESCRIPTION("USB Roccat char device");461MODULE_LICENSE("GPL v2");462