// SPDX-License-Identifier: GPL-2.0-or-later /* * Roccat driver for Linux * * Copyright (c) 2010 Stefan Achatz <erazor_de@users.sourceforge.net> */ /* */ /* * Module roccat is a char device used to report special events of roccat * hardware to userland. These events include requests for on-screen-display of * profile or dpi settings or requests for execution of macro sequences that are * not stored in device. The information in these events depends on hid device * implementation and contains data that is not available in a single hid event * or else hidraw could have been used. * It is inspired by hidraw, but uses only one circular buffer for all readers. */ #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt #include <linux/cdev.h> #include <linux/poll.h> #include <linux/sched/signal.h> #include <linux/hid-roccat.h> #include <linux/module.h> #define ROCCAT_FIRST_MINOR 0 #define ROCCAT_MAX_DEVICES 8 /* should be a power of 2 for performance reason */ #define ROCCAT_CBUF_SIZE 16 struct roccat_report { uint8_t *value; }; struct roccat_device { unsigned int minor; int report_size; int open; int exist; wait_queue_head_t wait; struct device *dev; struct hid_device *hid; struct list_head readers; /* protects modifications of readers list */ struct mutex readers_lock; /* * circular_buffer has one writer and multiple readers with their own * read pointers */ struct roccat_report cbuf[ROCCAT_CBUF_SIZE]; int cbuf_end; struct mutex cbuf_lock; }; struct roccat_reader { struct list_head node; struct roccat_device *device; int cbuf_start; }; static int roccat_major; static struct cdev roccat_cdev; static struct roccat_device *devices[ROCCAT_MAX_DEVICES]; /* protects modifications of devices array */ static DEFINE_MUTEX(devices_lock); static ssize_t roccat_read(struct file *file, char __user *buffer, size_t count, loff_t *ppos) { struct roccat_reader *reader = file->private_data; struct roccat_device *device = reader->device; struct roccat_report *report; ssize_t retval = 0, len; DECLARE_WAITQUEUE(wait, current); mutex_lock(&device->cbuf_lock); /* no data? */ if (reader->cbuf_start == device->cbuf_end) { add_wait_queue(&device->wait, &wait); set_current_state(TASK_INTERRUPTIBLE); /* wait for data */ while (reader->cbuf_start == device->cbuf_end) { if (file->f_flags & O_NONBLOCK) { retval = -EAGAIN; break; } if (signal_pending(current)) { retval = -ERESTARTSYS; break; } if (!device->exist) { retval = -EIO; break; } mutex_unlock(&device->cbuf_lock); schedule(); mutex_lock(&device->cbuf_lock); set_current_state(TASK_INTERRUPTIBLE); } set_current_state(TASK_RUNNING); remove_wait_queue(&device->wait, &wait); } /* here we either have data or a reason to return if retval is set */ if (retval) goto exit_unlock; report = &device->cbuf[reader->cbuf_start]; /* * If report is larger than requested amount of data, rest of report * is lost! */ len = device->report_size > count ? count : device->report_size; if (copy_to_user(buffer, report->value, len)) { retval = -EFAULT; goto exit_unlock; } retval += len; reader->cbuf_start = (reader->cbuf_start + 1) % ROCCAT_CBUF_SIZE; exit_unlock: mutex_unlock(&device->cbuf_lock); return retval; } static __poll_t roccat_poll(struct file *file, poll_table *wait) { struct roccat_reader *reader = file->private_data; poll_wait(file, &reader->device->wait, wait); if (reader->cbuf_start != reader->device->cbuf_end) return EPOLLIN | EPOLLRDNORM; if (!reader->device->exist) return EPOLLERR | EPOLLHUP; return 0; } static int roccat_open(struct inode *inode, struct file *file) { unsigned int minor = iminor(inode); struct roccat_reader *reader; struct roccat_device *device; int error = 0; reader = kzalloc(sizeof(struct roccat_reader), GFP_KERNEL); if (!reader) return -ENOMEM; mutex_lock(&devices_lock); device = devices[minor]; if (!device) { pr_emerg("roccat device with minor %d doesn't exist\n", minor); error = -ENODEV; goto exit_err_devices; } mutex_lock(&device->readers_lock); if (!device->open++) { /* power on device on adding first reader */ error = hid_hw_power(device->hid, PM_HINT_FULLON); if (error < 0) { --device->open; goto exit_err_readers; } error = hid_hw_open(device->hid); if (error < 0) { hid_hw_power(device->hid, PM_HINT_NORMAL); --device->open; goto exit_err_readers; } } reader->device = device; /* new reader doesn't get old events */ reader->cbuf_start = device->cbuf_end; list_add_tail(&reader->node, &device->readers); file->private_data = reader; exit_err_readers: mutex_unlock(&device->readers_lock); exit_err_devices: mutex_unlock(&devices_lock); if (error) kfree(reader); return error; } static int roccat_release(struct inode *inode, struct file *file) { unsigned int minor = iminor(inode); struct roccat_reader *reader = file->private_data; struct roccat_device *device; mutex_lock(&devices_lock); device = devices[minor]; if (!device) { mutex_unlock(&devices_lock); pr_emerg("roccat device with minor %d doesn't exist\n", minor); return -ENODEV; } mutex_lock(&device->readers_lock); list_del(&reader->node); mutex_unlock(&device->readers_lock); kfree(reader); if (!--device->open) { /* removing last reader */ if (device->exist) { hid_hw_power(device->hid, PM_HINT_NORMAL); hid_hw_close(device->hid); } else { kfree(device); } } mutex_unlock(&devices_lock); return 0; } /* * roccat_report_event() - output data to readers * @minor: minor device number returned by roccat_connect() * @data: pointer to data * * Return value is zero on success, a negative error code on failure. * * This is called from interrupt handler. */ int roccat_report_event(int minor, u8 const *data) { struct roccat_device *device; struct roccat_reader *reader; struct roccat_report *report; uint8_t *new_value; device = devices[minor]; new_value = kmemdup(data, device->report_size, GFP_ATOMIC); if (!new_value) return -ENOMEM; report = &device->cbuf[device->cbuf_end]; /* passing NULL is safe */ kfree(report->value); report->value = new_value; device->cbuf_end = (device->cbuf_end + 1) % ROCCAT_CBUF_SIZE; list_for_each_entry(reader, &device->readers, node) { /* * As we already inserted one element, the buffer can't be * empty. If start and end are equal, buffer is full and we * increase start, so that slow reader misses one event, but * gets the newer ones in the right order. */ if (reader->cbuf_start == device->cbuf_end) reader->cbuf_start = (reader->cbuf_start + 1) % ROCCAT_CBUF_SIZE; } wake_up_interruptible(&device->wait); return 0; } EXPORT_SYMBOL_GPL(roccat_report_event); /* * roccat_connect() - create a char device for special event output * @class: the class thats used to create the device. Meant to hold device * specific sysfs attributes. * @hid: the hid device the char device should be connected to. * @report_size: size of reports * * Return value is minor device number in Range [0, ROCCAT_MAX_DEVICES] on * success, a negative error code on failure. */ int roccat_connect(struct class *klass, struct hid_device *hid, int report_size) { unsigned int minor; struct roccat_device *device; int temp; device = kzalloc(sizeof(struct roccat_device), GFP_KERNEL); if (!device) return -ENOMEM; mutex_lock(&devices_lock); for (minor = 0; minor < ROCCAT_MAX_DEVICES; ++minor) { if (devices[minor]) continue; break; } if (minor < ROCCAT_MAX_DEVICES) { devices[minor] = device; } else { mutex_unlock(&devices_lock); kfree(device); return -EINVAL; } device->dev = device_create(klass, &hid->dev, MKDEV(roccat_major, minor), NULL, "%s%s%d", "roccat", hid->driver->name, minor); if (IS_ERR(device->dev)) { devices[minor] = NULL; mutex_unlock(&devices_lock); temp = PTR_ERR(device->dev); kfree(device); return temp; } mutex_unlock(&devices_lock); init_waitqueue_head(&device->wait); INIT_LIST_HEAD(&device->readers); mutex_init(&device->readers_lock); mutex_init(&device->cbuf_lock); device->minor = minor; device->hid = hid; device->exist = 1; device->cbuf_end = 0; device->report_size = report_size; return minor; } EXPORT_SYMBOL_GPL(roccat_connect); /* roccat_disconnect() - remove char device from hid device * @minor: the minor device number returned by roccat_connect() */ void roccat_disconnect(int minor) { struct roccat_device *device; mutex_lock(&devices_lock); device = devices[minor]; mutex_unlock(&devices_lock); device->exist = 0; /* TODO exist maybe not needed */ device_destroy(device->dev->class, MKDEV(roccat_major, minor)); mutex_lock(&devices_lock); devices[minor] = NULL; mutex_unlock(&devices_lock); if (device->open) { hid_hw_close(device->hid); wake_up_interruptible(&device->wait); } else { kfree(device); } } EXPORT_SYMBOL_GPL(roccat_disconnect); static long roccat_ioctl(struct file *file, unsigned int cmd, unsigned long arg) { struct inode *inode = file_inode(file); struct roccat_device *device; unsigned int minor = iminor(inode); long retval = 0; mutex_lock(&devices_lock); device = devices[minor]; if (!device) { retval = -ENODEV; goto out; } switch (cmd) { case ROCCATIOCGREPSIZE: if (put_user(device->report_size, (int __user *)arg)) retval = -EFAULT; break; default: retval = -ENOTTY; } out: mutex_unlock(&devices_lock); return retval; } static const struct file_operations roccat_ops = { .owner = THIS_MODULE, .read = roccat_read, .poll = roccat_poll, .open = roccat_open, .release = roccat_release, .llseek = noop_llseek, .unlocked_ioctl = roccat_ioctl, }; static int __init roccat_init(void) { int retval; dev_t dev_id; retval = alloc_chrdev_region(&dev_id, ROCCAT_FIRST_MINOR, ROCCAT_MAX_DEVICES, "roccat"); if (retval < 0) { pr_warn("can't get major number\n"); goto error; } roccat_major = MAJOR(dev_id); cdev_init(&roccat_cdev, &roccat_ops); retval = cdev_add(&roccat_cdev, dev_id, ROCCAT_MAX_DEVICES); if (retval < 0) { pr_warn("cannot add cdev\n"); goto cleanup_alloc_chrdev_region; } return 0; cleanup_alloc_chrdev_region: unregister_chrdev_region(dev_id, ROCCAT_MAX_DEVICES); error: return retval; } static void __exit roccat_exit(void) { dev_t dev_id = MKDEV(roccat_major, 0); cdev_del(&roccat_cdev); unregister_chrdev_region(dev_id, ROCCAT_MAX_DEVICES); } module_init(roccat_init); module_exit(roccat_exit); MODULE_AUTHOR("Stefan Achatz"); MODULE_DESCRIPTION("USB Roccat char device"); MODULE_LICENSE("GPL v2");