// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Roccat driver for Linux
*
* Copyright (c) 2010 Stefan Achatz <[email protected]>
*/
/*
*/
/*
* 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;
mutex_lock(&device->cbuf_lock);
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;
}
mutex_unlock(&device->cbuf_lock);
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(const 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");
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