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OMAP3 SRF: Generic shared resource f/w
[linux-ginger.git] / drivers / xen / evtchn.c
blob79bedba44feef5651177f10c2e3469e98a089e9a
1 /******************************************************************************
2 * evtchn.c
3 *
4 * Driver for receiving and demuxing event-channel signals.
5 *
6 * Copyright (c) 2004-2005, K A Fraser
7 * Multi-process extensions Copyright (c) 2004, Steven Smith
8 *
9 * This program is free software; you can redistribute it and/or
10 * modify it under the terms of the GNU General Public License version 2
11 * as published by the Free Software Foundation; or, when distributed
12 * separately from the Linux kernel or incorporated into other
13 * software packages, subject to the following license:
14 *
15 * Permission is hereby granted, free of charge, to any person obtaining a copy
16 * of this source file (the "Software"), to deal in the Software without
17 * restriction, including without limitation the rights to use, copy, modify,
18 * merge, publish, distribute, sublicense, and/or sell copies of the Software,
19 * and to permit persons to whom the Software is furnished to do so, subject to
20 * the following conditions:
21 *
22 * The above copyright notice and this permission notice shall be included in
23 * all copies or substantial portions of the Software.
24 *
25 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
26 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
27 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
28 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
29 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
30 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
31 * IN THE SOFTWARE.
32 */
33
34 #include <linux/module.h>
35 #include <linux/kernel.h>
36 #include <linux/sched.h>
37 #include <linux/slab.h>
38 #include <linux/string.h>
39 #include <linux/errno.h>
40 #include <linux/fs.h>
41 #include <linux/miscdevice.h>
42 #include <linux/major.h>
43 #include <linux/proc_fs.h>
44 #include <linux/stat.h>
45 #include <linux/poll.h>
46 #include <linux/irq.h>
47 #include <linux/init.h>
48 #include <linux/gfp.h>
49 #include <linux/mutex.h>
50 #include <linux/cpu.h>
51 #include <xen/events.h>
52 #include <xen/evtchn.h>
53 #include <asm/xen/hypervisor.h>
54
55 struct per_user_data {
56 struct mutex bind_mutex; /* serialize bind/unbind operations */
57
58 /* Notification ring, accessed via /dev/xen/evtchn. */
59 #define EVTCHN_RING_SIZE (PAGE_SIZE / sizeof(evtchn_port_t))
60 #define EVTCHN_RING_MASK(_i) ((_i)&(EVTCHN_RING_SIZE-1))
61 evtchn_port_t *ring;
62 unsigned int ring_cons, ring_prod, ring_overflow;
63 struct mutex ring_cons_mutex; /* protect against concurrent readers */
64
65 /* Processes wait on this queue when ring is empty. */
66 wait_queue_head_t evtchn_wait;
67 struct fasync_struct *evtchn_async_queue;
68 const char *name;
69 };
70
71 /* Who's bound to each port? */
72 static struct per_user_data *port_user[NR_EVENT_CHANNELS];
73 static DEFINE_SPINLOCK(port_user_lock); /* protects port_user[] and ring_prod */
74
75 irqreturn_t evtchn_interrupt(int irq, void *data)
76 {
77 unsigned int port = (unsigned long)data;
78 struct per_user_data *u;
79
80 spin_lock(&port_user_lock);
81
82 u = port_user[port];
83
84 disable_irq_nosync(irq);
85
86 if ((u->ring_prod - u->ring_cons) < EVTCHN_RING_SIZE) {
87 u->ring[EVTCHN_RING_MASK(u->ring_prod)] = port;
88 wmb(); /* Ensure ring contents visible */
89 if (u->ring_cons == u->ring_prod++) {
90 wake_up_interruptible(&u->evtchn_wait);
91 kill_fasync(&u->evtchn_async_queue,
92 SIGIO, POLL_IN);
93 }
94 } else {
95 u->ring_overflow = 1;
96 }
97
98 spin_unlock(&port_user_lock);
99
100 return IRQ_HANDLED;
101 }
102
103 static ssize_t evtchn_read(struct file *file, char __user *buf,
104 size_t count, loff_t *ppos)
105 {
106 int rc;
107 unsigned int c, p, bytes1 = 0, bytes2 = 0;
108 struct per_user_data *u = file->private_data;
109
110 /* Whole number of ports. */
111 count &= ~(sizeof(evtchn_port_t)-1);
112
113 if (count == 0)
114 return 0;
115
116 if (count > PAGE_SIZE)
117 count = PAGE_SIZE;
118
119 for (;;) {
120 mutex_lock(&u->ring_cons_mutex);
121
122 rc = -EFBIG;
123 if (u->ring_overflow)
124 goto unlock_out;
125
126 c = u->ring_cons;
127 p = u->ring_prod;
128 if (c != p)
129 break;
130
131 mutex_unlock(&u->ring_cons_mutex);
132
133 if (file->f_flags & O_NONBLOCK)
134 return -EAGAIN;
135
136 rc = wait_event_interruptible(u->evtchn_wait,
137 u->ring_cons != u->ring_prod);
138 if (rc)
139 return rc;
140 }
141
142 /* Byte lengths of two chunks. Chunk split (if any) is at ring wrap. */
143 if (((c ^ p) & EVTCHN_RING_SIZE) != 0) {
144 bytes1 = (EVTCHN_RING_SIZE - EVTCHN_RING_MASK(c)) *
145 sizeof(evtchn_port_t);
146 bytes2 = EVTCHN_RING_MASK(p) * sizeof(evtchn_port_t);
147 } else {
148 bytes1 = (p - c) * sizeof(evtchn_port_t);
149 bytes2 = 0;
150 }
151
152 /* Truncate chunks according to caller's maximum byte count. */
153 if (bytes1 > count) {
154 bytes1 = count;
155 bytes2 = 0;
156 } else if ((bytes1 + bytes2) > count) {
157 bytes2 = count - bytes1;
158 }
159
160 rc = -EFAULT;
161 rmb(); /* Ensure that we see the port before we copy it. */
162 if (copy_to_user(buf, &u->ring[EVTCHN_RING_MASK(c)], bytes1) ||
163 ((bytes2 != 0) &&
164 copy_to_user(&buf[bytes1], &u->ring[0], bytes2)))
165 goto unlock_out;
166
167 u->ring_cons += (bytes1 + bytes2) / sizeof(evtchn_port_t);
168 rc = bytes1 + bytes2;
169
170 unlock_out:
171 mutex_unlock(&u->ring_cons_mutex);
172 return rc;
173 }
174
175 static ssize_t evtchn_write(struct file *file, const char __user *buf,
176 size_t count, loff_t *ppos)
177 {
178 int rc, i;
179 evtchn_port_t *kbuf = (evtchn_port_t *)__get_free_page(GFP_KERNEL);
180 struct per_user_data *u = file->private_data;
181
182 if (kbuf == NULL)
183 return -ENOMEM;
184
185 /* Whole number of ports. */
186 count &= ~(sizeof(evtchn_port_t)-1);
187
188 rc = 0;
189 if (count == 0)
190 goto out;
191
192 if (count > PAGE_SIZE)
193 count = PAGE_SIZE;
194
195 rc = -EFAULT;
196 if (copy_from_user(kbuf, buf, count) != 0)
197 goto out;
198
199 spin_lock_irq(&port_user_lock);
200 for (i = 0; i < (count/sizeof(evtchn_port_t)); i++)
201 if ((kbuf[i] < NR_EVENT_CHANNELS) && (port_user[kbuf[i]] == u))
202 enable_irq(irq_from_evtchn(kbuf[i]));
203 spin_unlock_irq(&port_user_lock);
204
205 rc = count;
206
207 out:
208 free_page((unsigned long)kbuf);
209 return rc;
210 }
211
212 static int evtchn_bind_to_user(struct per_user_data *u, int port)
213 {
214 int rc = 0;
215
216 /*
217 * Ports are never reused, so every caller should pass in a
218 * unique port.
219 *
220 * (Locking not necessary because we haven't registered the
221 * interrupt handler yet, and our caller has already
222 * serialized bind operations.)
223 */
224 BUG_ON(port_user[port] != NULL);
225 port_user[port] = u;
226
227 rc = bind_evtchn_to_irqhandler(port, evtchn_interrupt, IRQF_DISABLED,
228 u->name, (void *)(unsigned long)port);
229 if (rc >= 0)
230 rc = 0;
231
232 return rc;
233 }
234
235 static void evtchn_unbind_from_user(struct per_user_data *u, int port)
236 {
237 int irq = irq_from_evtchn(port);
238
239 unbind_from_irqhandler(irq, (void *)(unsigned long)port);
240
241 /* make sure we unbind the irq handler before clearing the port */
242 barrier();
243
244 port_user[port] = NULL;
245 }
246
247 static long evtchn_ioctl(struct file *file,
248 unsigned int cmd, unsigned long arg)
249 {
250 int rc;
251 struct per_user_data *u = file->private_data;
252 void __user *uarg = (void __user *) arg;
253
254 /* Prevent bind from racing with unbind */
255 mutex_lock(&u->bind_mutex);
256
257 switch (cmd) {
258 case IOCTL_EVTCHN_BIND_VIRQ: {
259 struct ioctl_evtchn_bind_virq bind;
260 struct evtchn_bind_virq bind_virq;
261
262 rc = -EFAULT;
263 if (copy_from_user(&bind, uarg, sizeof(bind)))
264 break;
265
266 bind_virq.virq = bind.virq;
267 bind_virq.vcpu = 0;
268 rc = HYPERVISOR_event_channel_op(EVTCHNOP_bind_virq,
269 &bind_virq);
270 if (rc != 0)
271 break;
272
273 rc = evtchn_bind_to_user(u, bind_virq.port);
274 if (rc == 0)
275 rc = bind_virq.port;
276 break;
277 }
278
279 case IOCTL_EVTCHN_BIND_INTERDOMAIN: {
280 struct ioctl_evtchn_bind_interdomain bind;
281 struct evtchn_bind_interdomain bind_interdomain;
282
283 rc = -EFAULT;
284 if (copy_from_user(&bind, uarg, sizeof(bind)))
285 break;
286
287 bind_interdomain.remote_dom = bind.remote_domain;
288 bind_interdomain.remote_port = bind.remote_port;
289 rc = HYPERVISOR_event_channel_op(EVTCHNOP_bind_interdomain,
290 &bind_interdomain);
291 if (rc != 0)
292 break;
293
294 rc = evtchn_bind_to_user(u, bind_interdomain.local_port);
295 if (rc == 0)
296 rc = bind_interdomain.local_port;
297 break;
298 }
299
300 case IOCTL_EVTCHN_BIND_UNBOUND_PORT: {
301 struct ioctl_evtchn_bind_unbound_port bind;
302 struct evtchn_alloc_unbound alloc_unbound;
303
304 rc = -EFAULT;
305 if (copy_from_user(&bind, uarg, sizeof(bind)))
306 break;
307
308 alloc_unbound.dom = DOMID_SELF;
309 alloc_unbound.remote_dom = bind.remote_domain;
310 rc = HYPERVISOR_event_channel_op(EVTCHNOP_alloc_unbound,
311 &alloc_unbound);
312 if (rc != 0)
313 break;
314
315 rc = evtchn_bind_to_user(u, alloc_unbound.port);
316 if (rc == 0)
317 rc = alloc_unbound.port;
318 break;
319 }
320
321 case IOCTL_EVTCHN_UNBIND: {
322 struct ioctl_evtchn_unbind unbind;
323
324 rc = -EFAULT;
325 if (copy_from_user(&unbind, uarg, sizeof(unbind)))
326 break;
327
328 rc = -EINVAL;
329 if (unbind.port >= NR_EVENT_CHANNELS)
330 break;
331
332 spin_lock_irq(&port_user_lock);
333
334 rc = -ENOTCONN;
335 if (port_user[unbind.port] != u) {
336 spin_unlock_irq(&port_user_lock);
337 break;
338 }
339
340 evtchn_unbind_from_user(u, unbind.port);
341
342 spin_unlock_irq(&port_user_lock);
343
344 rc = 0;
345 break;
346 }
347
348 case IOCTL_EVTCHN_NOTIFY: {
349 struct ioctl_evtchn_notify notify;
350
351 rc = -EFAULT;
352 if (copy_from_user(&notify, uarg, sizeof(notify)))
353 break;
354
355 if (notify.port >= NR_EVENT_CHANNELS) {
356 rc = -EINVAL;
357 } else if (port_user[notify.port] != u) {
358 rc = -ENOTCONN;
359 } else {
360 notify_remote_via_evtchn(notify.port);
361 rc = 0;
362 }
363 break;
364 }
365
366 case IOCTL_EVTCHN_RESET: {
367 /* Initialise the ring to empty. Clear errors. */
368 mutex_lock(&u->ring_cons_mutex);
369 spin_lock_irq(&port_user_lock);
370 u->ring_cons = u->ring_prod = u->ring_overflow = 0;
371 spin_unlock_irq(&port_user_lock);
372 mutex_unlock(&u->ring_cons_mutex);
373 rc = 0;
374 break;
375 }
376
377 default:
378 rc = -ENOSYS;
379 break;
380 }
381 mutex_unlock(&u->bind_mutex);
382
383 return rc;
384 }
385
386 static unsigned int evtchn_poll(struct file *file, poll_table *wait)
387 {
388 unsigned int mask = POLLOUT | POLLWRNORM;
389 struct per_user_data *u = file->private_data;
390
391 poll_wait(file, &u->evtchn_wait, wait);
392 if (u->ring_cons != u->ring_prod)
393 mask |= POLLIN | POLLRDNORM;
394 if (u->ring_overflow)
395 mask = POLLERR;
396 return mask;
397 }
398
399 static int evtchn_fasync(int fd, struct file *filp, int on)
400 {
401 struct per_user_data *u = filp->private_data;
402 return fasync_helper(fd, filp, on, &u->evtchn_async_queue);
403 }
404
405 static int evtchn_open(struct inode *inode, struct file *filp)
406 {
407 struct per_user_data *u;
408
409 u = kzalloc(sizeof(*u), GFP_KERNEL);
410 if (u == NULL)
411 return -ENOMEM;
412
413 u->name = kasprintf(GFP_KERNEL, "evtchn:%s", current->comm);
414 if (u->name == NULL) {
415 kfree(u);
416 return -ENOMEM;
417 }
418
419 init_waitqueue_head(&u->evtchn_wait);
420
421 u->ring = (evtchn_port_t *)__get_free_page(GFP_KERNEL);
422 if (u->ring == NULL) {
423 kfree(u->name);
424 kfree(u);
425 return -ENOMEM;
426 }
427
428 mutex_init(&u->bind_mutex);
429 mutex_init(&u->ring_cons_mutex);
430
431 filp->private_data = u;
432
433 return 0;
434 }
435
436 static int evtchn_release(struct inode *inode, struct file *filp)
437 {
438 int i;
439 struct per_user_data *u = filp->private_data;
440
441 spin_lock_irq(&port_user_lock);
442
443 free_page((unsigned long)u->ring);
444
445 for (i = 0; i < NR_EVENT_CHANNELS; i++) {
446 if (port_user[i] != u)
447 continue;
448
449 evtchn_unbind_from_user(port_user[i], i);
450 }
451
452 spin_unlock_irq(&port_user_lock);
453
454 kfree(u->name);
455 kfree(u);
456
457 return 0;
458 }
459
460 static const struct file_operations evtchn_fops = {
461 .owner = THIS_MODULE,
462 .read = evtchn_read,
463 .write = evtchn_write,
464 .unlocked_ioctl = evtchn_ioctl,
465 .poll = evtchn_poll,
466 .fasync = evtchn_fasync,
467 .open = evtchn_open,
468 .release = evtchn_release,
469 };
470
471 static struct miscdevice evtchn_miscdev = {
472 .minor = MISC_DYNAMIC_MINOR,
473 .name = "evtchn",
474 .fops = &evtchn_fops,
475 };
476 static int __init evtchn_init(void)
477 {
478 int err;
479
480 if (!xen_domain())
481 return -ENODEV;
482
483 spin_lock_init(&port_user_lock);
484 memset(port_user, 0, sizeof(port_user));
485
486 /* Create '/dev/misc/evtchn'. */
487 err = misc_register(&evtchn_miscdev);
488 if (err != 0) {
489 printk(KERN_ALERT "Could not register /dev/misc/evtchn\n");
490 return err;
491 }
492
493 printk(KERN_INFO "Event-channel device installed.\n");
494
495 return 0;
496 }
497
498 static void __exit evtchn_cleanup(void)
499 {
500 misc_deregister(&evtchn_miscdev);
501 }
502
503 module_init(evtchn_init);
504 module_exit(evtchn_cleanup);
505
506 MODULE_LICENSE("GPL");
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