1/*
2 * Roccat driver for Linux
3 *
4 * Copyright (c) 2010 Stefan Achatz <erazor_de@users.sourceforge.net>
5 */
6
7/*
8 * This program is free software; you can redistribute it and/or modify it
9 * under the terms of the GNU General Public License as published by the Free
10 * Software Foundation; either version 2 of the License, or (at your option)
11 * any later version.
12 */
13
14/*
15 * Module roccat is a char device used to report special events of roccat
16 * hardware to userland. These events include requests for on-screen-display of
17 * profile or dpi settings or requests for execution of macro sequences that are
18 * not stored in device. The information in these events depends on hid device
19 * implementation and contains data that is not available in a single hid event
20 * or else hidraw could have been used.
21 * It is inspired by hidraw, but uses only one circular buffer for all readers.
22 */
23
24#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
25
26#include <linux/cdev.h>
27#include <linux/poll.h>
28#include <linux/sched.h>
29#include <linux/hid-roccat.h>
30#include <linux/module.h>
31
32#define ROCCAT_FIRST_MINOR 0
33#define ROCCAT_MAX_DEVICES 8
34
35/* should be a power of 2 for performance reason */
36#define ROCCAT_CBUF_SIZE 16
37
38struct roccat_report {
39	uint8_t *value;
40};
41
42struct roccat_device {
43	unsigned int minor;
44	int report_size;
45	int open;
46	int exist;
47	wait_queue_head_t wait;
48	struct device *dev;
49	struct hid_device *hid;
50	struct list_head readers;
51	/* protects modifications of readers list */
52	struct mutex readers_lock;
53
54	/*
55	 * circular_buffer has one writer and multiple readers with their own
56	 * read pointers
57	 */
58	struct roccat_report cbuf[ROCCAT_CBUF_SIZE];
59	int cbuf_end;
60	struct mutex cbuf_lock;
61};
62
63struct roccat_reader {
64	struct list_head node;
65	struct roccat_device *device;
66	int cbuf_start;
67};
68
69static int roccat_major;
70static struct cdev roccat_cdev;
71
72static struct roccat_device *devices[ROCCAT_MAX_DEVICES];
73/* protects modifications of devices array */
74static DEFINE_MUTEX(devices_lock);
75
76static ssize_t roccat_read(struct file *file, char __user *buffer,
77		size_t count, loff_t *ppos)
78{
79	struct roccat_reader *reader = file->private_data;
80	struct roccat_device *device = reader->device;
81	struct roccat_report *report;
82	ssize_t retval = 0, len;
83	DECLARE_WAITQUEUE(wait, current);
84
85	mutex_lock(&device->cbuf_lock);
86
87	/* no data? */
88	if (reader->cbuf_start == device->cbuf_end) {
89		add_wait_queue(&device->wait, &wait);
90		set_current_state(TASK_INTERRUPTIBLE);
91
92		/* wait for data */
93		while (reader->cbuf_start == device->cbuf_end) {
94			if (file->f_flags & O_NONBLOCK) {
95				retval = -EAGAIN;
96				break;
97			}
98			if (signal_pending(current)) {
99				retval = -ERESTARTSYS;
100				break;
101			}
102			if (!device->exist) {
103				retval = -EIO;
104				break;
105			}
106
107			mutex_unlock(&device->cbuf_lock);
108			schedule();
109			mutex_lock(&device->cbuf_lock);
110			set_current_state(TASK_INTERRUPTIBLE);
111		}
112
113		set_current_state(TASK_RUNNING);
114		remove_wait_queue(&device->wait, &wait);
115	}
116
117	/* here we either have data or a reason to return if retval is set */
118	if (retval)
119		goto exit_unlock;
120
121	report = &device->cbuf[reader->cbuf_start];
122	/*
123	 * If report is larger than requested amount of data, rest of report
124	 * is lost!
125	 */
126	len = device->report_size > count ? count : device->report_size;
127
128	if (copy_to_user(buffer, report->value, len)) {
129		retval = -EFAULT;
130		goto exit_unlock;
131	}
132	retval += len;
133	reader->cbuf_start = (reader->cbuf_start + 1) % ROCCAT_CBUF_SIZE;
134
135exit_unlock:
136	mutex_unlock(&device->cbuf_lock);
137	return retval;
138}
139
140static unsigned int roccat_poll(struct file *file, poll_table *wait)
141{
142	struct roccat_reader *reader = file->private_data;
143	poll_wait(file, &reader->device->wait, wait);
144	if (reader->cbuf_start != reader->device->cbuf_end)
145		return POLLIN | POLLRDNORM;
146	if (!reader->device->exist)
147		return POLLERR | POLLHUP;
148	return 0;
149}
150
151static int roccat_open(struct inode *inode, struct file *file)
152{
153	unsigned int minor = iminor(inode);
154	struct roccat_reader *reader;
155	struct roccat_device *device;
156	int error = 0;
157
158	reader = kzalloc(sizeof(struct roccat_reader), GFP_KERNEL);
159	if (!reader)
160		return -ENOMEM;
161
162	mutex_lock(&devices_lock);
163
164	device = devices[minor];
165
166	if (!device) {
167		pr_emerg("roccat device with minor %d doesn't exist\n", minor);
168		error = -ENODEV;
169		goto exit_err_devices;
170	}
171
172	mutex_lock(&device->readers_lock);
173
174	if (!device->open++) {
175		/* power on device on adding first reader */
176		error = hid_hw_power(device->hid, PM_HINT_FULLON);
177		if (error < 0) {
178			--device->open;
179			goto exit_err_readers;
180		}
181
182		error = hid_hw_open(device->hid);
183		if (error < 0) {
184			hid_hw_power(device->hid, PM_HINT_NORMAL);
185			--device->open;
186			goto exit_err_readers;
187		}
188	}
189
190	reader->device = device;
191	/* new reader doesn't get old events */
192	reader->cbuf_start = device->cbuf_end;
193
194	list_add_tail(&reader->node, &device->readers);
195	file->private_data = reader;
196
197exit_err_readers:
198	mutex_unlock(&device->readers_lock);
199exit_err_devices:
200	mutex_unlock(&devices_lock);
201	if (error)
202		kfree(reader);
203	return error;
204}
205
206static int roccat_release(struct inode *inode, struct file *file)
207{
208	unsigned int minor = iminor(inode);
209	struct roccat_reader *reader = file->private_data;
210	struct roccat_device *device;
211
212	mutex_lock(&devices_lock);
213
214	device = devices[minor];
215	if (!device) {
216		mutex_unlock(&devices_lock);
217		pr_emerg("roccat device with minor %d doesn't exist\n", minor);
218		return -ENODEV;
219	}
220
221	mutex_lock(&device->readers_lock);
222	list_del(&reader->node);
223	mutex_unlock(&device->readers_lock);
224	kfree(reader);
225
226	if (!--device->open) {
227		/* removing last reader */
228		if (device->exist) {
229			hid_hw_power(device->hid, PM_HINT_NORMAL);
230			hid_hw_close(device->hid);
231		} else {
232			kfree(device);
233		}
234	}
235
236	mutex_unlock(&devices_lock);
237
238	return 0;
239}
240
241/*
242 * roccat_report_event() - output data to readers
243 * @minor: minor device number returned by roccat_connect()
244 * @data: pointer to data
245 *
246 * Return value is zero on success, a negative error code on failure.
247 *
248 * This is called from interrupt handler.
249 */
250int roccat_report_event(int minor, u8 const *data)
251{
252	struct roccat_device *device;
253	struct roccat_reader *reader;
254	struct roccat_report *report;
255	uint8_t *new_value;
256
257	device = devices[minor];
258
259	new_value = kmemdup(data, device->report_size, GFP_ATOMIC);
260	if (!new_value)
261		return -ENOMEM;
262
263	report = &device->cbuf[device->cbuf_end];
264
265	/* passing NULL is safe */
266	kfree(report->value);
267
268	report->value = new_value;
269	device->cbuf_end = (device->cbuf_end + 1) % ROCCAT_CBUF_SIZE;
270
271	list_for_each_entry(reader, &device->readers, node) {
272		/*
273		 * As we already inserted one element, the buffer can't be
274		 * empty. If start and end are equal, buffer is full and we
275		 * increase start, so that slow reader misses one event, but
276		 * gets the newer ones in the right order.
277		 */
278		if (reader->cbuf_start == device->cbuf_end)
279			reader->cbuf_start = (reader->cbuf_start + 1) % ROCCAT_CBUF_SIZE;
280	}
281
282	wake_up_interruptible(&device->wait);
283	return 0;
284}
285EXPORT_SYMBOL_GPL(roccat_report_event);
286
287/*
288 * roccat_connect() - create a char device for special event output
289 * @class: the class thats used to create the device. Meant to hold device
290 * specific sysfs attributes.
291 * @hid: the hid device the char device should be connected to.
292 * @report_size: size of reports
293 *
294 * Return value is minor device number in Range [0, ROCCAT_MAX_DEVICES] on
295 * success, a negative error code on failure.
296 */
297int roccat_connect(struct class *klass, struct hid_device *hid, int report_size)
298{
299	unsigned int minor;
300	struct roccat_device *device;
301	int temp;
302
303	device = kzalloc(sizeof(struct roccat_device), GFP_KERNEL);
304	if (!device)
305		return -ENOMEM;
306
307	mutex_lock(&devices_lock);
308
309	for (minor = 0; minor < ROCCAT_MAX_DEVICES; ++minor) {
310		if (devices[minor])
311			continue;
312		break;
313	}
314
315	if (minor < ROCCAT_MAX_DEVICES) {
316		devices[minor] = device;
317	} else {
318		mutex_unlock(&devices_lock);
319		kfree(device);
320		return -EINVAL;
321	}
322
323	device->dev = device_create(klass, &hid->dev,
324			MKDEV(roccat_major, minor), NULL,
325			"%s%s%d", "roccat", hid->driver->name, minor);
326
327	if (IS_ERR(device->dev)) {
328		devices[minor] = NULL;
329		mutex_unlock(&devices_lock);
330		temp = PTR_ERR(device->dev);
331		kfree(device);
332		return temp;
333	}
334
335	mutex_unlock(&devices_lock);
336
337	init_waitqueue_head(&device->wait);
338	INIT_LIST_HEAD(&device->readers);
339	mutex_init(&device->readers_lock);
340	mutex_init(&device->cbuf_lock);
341	device->minor = minor;
342	device->hid = hid;
343	device->exist = 1;
344	device->cbuf_end = 0;
345	device->report_size = report_size;
346
347	return minor;
348}
349EXPORT_SYMBOL_GPL(roccat_connect);
350
351/* roccat_disconnect() - remove char device from hid device
352 * @minor: the minor device number returned by roccat_connect()
353 */
354void roccat_disconnect(int minor)
355{
356	struct roccat_device *device;
357
358	mutex_lock(&devices_lock);
359	device = devices[minor];
360	mutex_unlock(&devices_lock);
361
362	device->exist = 0; /* TODO exist maybe not needed */
363
364	device_destroy(device->dev->class, MKDEV(roccat_major, minor));
365
366	mutex_lock(&devices_lock);
367	devices[minor] = NULL;
368	mutex_unlock(&devices_lock);
369
370	if (device->open) {
371		hid_hw_close(device->hid);
372		wake_up_interruptible(&device->wait);
373	} else {
374		kfree(device);
375	}
376}
377EXPORT_SYMBOL_GPL(roccat_disconnect);
378
379static long roccat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
380{
381	struct inode *inode = file_inode(file);
382	struct roccat_device *device;
383	unsigned int minor = iminor(inode);
384	long retval = 0;
385
386	mutex_lock(&devices_lock);
387
388	device = devices[minor];
389	if (!device) {
390		retval = -ENODEV;
391		goto out;
392	}
393
394	switch (cmd) {
395	case ROCCATIOCGREPSIZE:
396		if (put_user(device->report_size, (int __user *)arg))
397			retval = -EFAULT;
398		break;
399	default:
400		retval = -ENOTTY;
401	}
402out:
403	mutex_unlock(&devices_lock);
404	return retval;
405}
406
407static const struct file_operations roccat_ops = {
408	.owner = THIS_MODULE,
409	.read = roccat_read,
410	.poll = roccat_poll,
411	.open = roccat_open,
412	.release = roccat_release,
413	.llseek = noop_llseek,
414	.unlocked_ioctl = roccat_ioctl,
415};
416
417static int __init roccat_init(void)
418{
419	int retval;
420	dev_t dev_id;
421
422	retval = alloc_chrdev_region(&dev_id, ROCCAT_FIRST_MINOR,
423			ROCCAT_MAX_DEVICES, "roccat");
424
425	roccat_major = MAJOR(dev_id);
426
427	if (retval < 0) {
428		pr_warn("can't get major number\n");
429		goto error;
430	}
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