xref: /openbmc/linux/arch/mips/kernel/rtlx.c (revision 9ac8d3fb) 
1 /*
2  * Copyright (C) 2005 MIPS Technologies, Inc.  All rights reserved.
3  * Copyright (C) 2005, 06 Ralf Baechle (ralf@linux-mips.org)
4  *
5  *  This program is free software; you can distribute it and/or modify it
6  *  under the terms of the GNU General Public License (Version 2) as
7  *  published by the Free Software Foundation.
8  *
9  *  This program is distributed in the hope it will be useful, but WITHOUT
10  *  ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11  *  FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
12  *  for more details.
13  *
14  *  You should have received a copy of the GNU General Public License along
15  *  with this program; if not, write to the Free Software Foundation, Inc.,
16  *  59 Temple Place - Suite 330, Boston MA 02111-1307, USA.
17  *
18  */
19 
20 #include <linux/device.h>
21 #include <linux/kernel.h>
22 #include <linux/module.h>
23 #include <linux/fs.h>
24 #include <linux/init.h>
25 #include <asm/uaccess.h>
26 #include <linux/slab.h>
27 #include <linux/list.h>
28 #include <linux/vmalloc.h>
29 #include <linux/elf.h>
30 #include <linux/seq_file.h>
31 #include <linux/smp_lock.h>
32 #include <linux/syscalls.h>
33 #include <linux/moduleloader.h>
34 #include <linux/interrupt.h>
35 #include <linux/poll.h>
36 #include <linux/sched.h>
37 #include <linux/wait.h>
38 #include <asm/mipsmtregs.h>
39 #include <asm/mips_mt.h>
40 #include <asm/cacheflush.h>
41 #include <asm/atomic.h>
42 #include <asm/cpu.h>
43 #include <asm/processor.h>
44 #include <asm/system.h>
45 #include <asm/vpe.h>
46 #include <asm/rtlx.h>
47 
48 static struct rtlx_info *rtlx;
49 static int major;
50 static char module_name[] = "rtlx";
51 
52 static struct chan_waitqueues {
53 	wait_queue_head_t rt_queue;
54 	wait_queue_head_t lx_queue;
55 	atomic_t in_open;
56 	struct mutex mutex;
57 } channel_wqs[RTLX_CHANNELS];
58 
59 static struct vpe_notifications notify;
60 static int sp_stopping = 0;
61 
62 extern void *vpe_get_shared(int index);
63 
64 static void rtlx_dispatch(void)
65 {
66 	do_IRQ(MIPS_CPU_IRQ_BASE + MIPS_CPU_RTLX_IRQ);
67 }
68 
69 
70 /* Interrupt handler may be called before rtlx_init has otherwise had
71    a chance to run.
72 */
73 static irqreturn_t rtlx_interrupt(int irq, void *dev_id)
74 {
75 	int i;
76 	unsigned int flags, vpeflags;
77 
78 	/* Ought not to be strictly necessary for SMTC builds */
79 	local_irq_save(flags);
80 	vpeflags = dvpe();
81 	set_c0_status(0x100 << MIPS_CPU_RTLX_IRQ);
82 	irq_enable_hazard();
83 	evpe(vpeflags);
84 	local_irq_restore(flags);
85 
86 	for (i = 0; i < RTLX_CHANNELS; i++) {
87 			wake_up(&channel_wqs[i].lx_queue);
88 			wake_up(&channel_wqs[i].rt_queue);
89 	}
90 
91 	return IRQ_HANDLED;
92 }
93 
94 static void __used dump_rtlx(void)
95 {
96 	int i;
97 
98 	printk("id 0x%lx state %d\n", rtlx->id, rtlx->state);
99 
100 	for (i = 0; i < RTLX_CHANNELS; i++) {
101 		struct rtlx_channel *chan = &rtlx->channel[i];
102 
103 		printk(" rt_state %d lx_state %d buffer_size %d\n",
104 		       chan->rt_state, chan->lx_state, chan->buffer_size);
105 
106 		printk(" rt_read %d rt_write %d\n",
107 		       chan->rt_read, chan->rt_write);
108 
109 		printk(" lx_read %d lx_write %d\n",
110 		       chan->lx_read, chan->lx_write);
111 
112 		printk(" rt_buffer <%s>\n", chan->rt_buffer);
113 		printk(" lx_buffer <%s>\n", chan->lx_buffer);
114 	}
115 }
116 
117 /* call when we have the address of the shared structure from the SP side. */
118 static int rtlx_init(struct rtlx_info *rtlxi)
119 {
120 	if (rtlxi->id != RTLX_ID) {
121 		printk(KERN_ERR "no valid RTLX id at 0x%p 0x%lx\n",
122 			rtlxi, rtlxi->id);
123 		return -ENOEXEC;
124 	}
125 
126 	rtlx = rtlxi;
127 
128 	return 0;
129 }
130 
131 /* notifications */
132 static void starting(int vpe)
133 {
134 	int i;
135 	sp_stopping = 0;
136 
137 	/* force a reload of rtlx */
138 	rtlx=NULL;
139 
140 	/* wake up any sleeping rtlx_open's */
141 	for (i = 0; i < RTLX_CHANNELS; i++)
142 		wake_up_interruptible(&channel_wqs[i].lx_queue);
143 }
144 
145 static void stopping(int vpe)
146 {
147 	int i;
148 
149 	sp_stopping = 1;
150 	for (i = 0; i < RTLX_CHANNELS; i++)
151 		wake_up_interruptible(&channel_wqs[i].lx_queue);
152 }
153 
154 
155 int rtlx_open(int index, int can_sleep)
156 {
157 	struct rtlx_info **p;
158 	struct rtlx_channel *chan;
159 	enum rtlx_state state;
160 	int ret = 0;
161 
162 	if (index >= RTLX_CHANNELS) {
163 		printk(KERN_DEBUG "rtlx_open index out of range\n");
164 		return -ENOSYS;
165 	}
166 
167 	if (atomic_inc_return(&channel_wqs[index].in_open) > 1) {
168 		printk(KERN_DEBUG "rtlx_open channel %d already opened\n",
169 		       index);
170 		ret = -EBUSY;
171 		goto out_fail;
172 	}
173 
174 	if (rtlx == NULL) {
175 		if( (p = vpe_get_shared(tclimit)) == NULL) {
176 		    if (can_sleep) {
177 			__wait_event_interruptible(channel_wqs[index].lx_queue,
178 				(p = vpe_get_shared(tclimit)), ret);
179 			if (ret)
180 				goto out_fail;
181 		    } else {
182 			printk(KERN_DEBUG "No SP program loaded, and device "
183 					"opened with O_NONBLOCK\n");
184 			ret = -ENOSYS;
185 			goto out_fail;
186 		    }
187 		}
188 
189 		smp_rmb();
190 		if (*p == NULL) {
191 			if (can_sleep) {
192 				DEFINE_WAIT(wait);
193 
194 				for (;;) {
195 					prepare_to_wait(
196 						&channel_wqs[index].lx_queue,
197 						&wait, TASK_INTERRUPTIBLE);
198 					smp_rmb();
199 					if (*p != NULL)
200 						break;
201 					if (!signal_pending(current)) {
202 						schedule();
203 						continue;
204 					}
205 					ret = -ERESTARTSYS;
206 					goto out_fail;
207 				}
208 				finish_wait(&channel_wqs[index].lx_queue, &wait);
209 			} else {
210 				pr_err(" *vpe_get_shared is NULL. "
211 				       "Has an SP program been loaded?\n");
212 				ret = -ENOSYS;
213 				goto out_fail;
214 			}
215 		}
216 
217 		if ((unsigned int)*p < KSEG0) {
218 			printk(KERN_WARNING "vpe_get_shared returned an "
219 			       "invalid pointer maybe an error code %d\n",
220 			       (int)*p);
221 			ret = -ENOSYS;
222 			goto out_fail;
223 		}
224 
225 		if ((ret = rtlx_init(*p)) < 0)
226 			goto out_ret;
227 	}
228 
229 	chan = &rtlx->channel[index];
230 
231 	state = xchg(&chan->lx_state, RTLX_STATE_OPENED);
232 	if (state == RTLX_STATE_OPENED) {
233 		ret = -EBUSY;
234 		goto out_fail;
235 	}
236 
237 out_fail:
238 	smp_mb();
239 	atomic_dec(&channel_wqs[index].in_open);
240 	smp_mb();
241 
242 out_ret:
243 	return ret;
244 }
245 
246 int rtlx_release(int index)
247 {
248 	if (rtlx == NULL) {
249 		pr_err("rtlx_release() with null rtlx\n");
250 		return 0;
251 	}
252 	rtlx->channel[index].lx_state = RTLX_STATE_UNUSED;
253 	return 0;
254 }
255 
256 unsigned int rtlx_read_poll(int index, int can_sleep)
257 {
258  	struct rtlx_channel *chan;
259 
260  	if (rtlx == NULL)
261  		return 0;
262 
263  	chan = &rtlx->channel[index];
264 
265 	/* data available to read? */
266 	if (chan->lx_read == chan->lx_write) {
267 		if (can_sleep) {
268 			int ret = 0;
269 
270 			__wait_event_interruptible(channel_wqs[index].lx_queue,
271 				(chan->lx_read != chan->lx_write) ||
272 				sp_stopping, ret);
273 			if (ret)
274 				return ret;
275 
276 			if (sp_stopping)
277 				return 0;
278 		} else
279 			return 0;
280 	}
281 
282 	return (chan->lx_write + chan->buffer_size - chan->lx_read)
283 	       % chan->buffer_size;
284 }
285 
286 static inline int write_spacefree(int read, int write, int size)
287 {
288 	if (read == write) {
289 		/*
290 		 * Never fill the buffer completely, so indexes are always
291 		 * equal if empty and only empty, or !equal if data available
292 		 */
293 		return size - 1;
294 	}
295 
296 	return ((read + size - write) % size) - 1;
297 }
298 
299 unsigned int rtlx_write_poll(int index)
300 {
301 	struct rtlx_channel *chan = &rtlx->channel[index];
302 
303 	return write_spacefree(chan->rt_read, chan->rt_write,
304 				chan->buffer_size);
305 }
306 
307 ssize_t rtlx_read(int index, void __user *buff, size_t count)
308 {
309 	size_t lx_write, fl = 0L;
310 	struct rtlx_channel *lx;
311 	unsigned long failed;
312 
313 	if (rtlx == NULL)
314 		return -ENOSYS;
315 
316 	lx = &rtlx->channel[index];
317 
318 	mutex_lock(&channel_wqs[index].mutex);
319 	smp_rmb();
320 	lx_write = lx->lx_write;
321 
322 	/* find out how much in total */
323 	count = min(count,
324 		     (size_t)(lx_write + lx->buffer_size - lx->lx_read)
325 		     % lx->buffer_size);
326 
327 	/* then how much from the read pointer onwards */
328 	fl = min(count, (size_t)lx->buffer_size - lx->lx_read);
329 
330 	failed = copy_to_user(buff, lx->lx_buffer + lx->lx_read, fl);
331 	if (failed)
332 		goto out;
333 
334 	/* and if there is anything left at the beginning of the buffer */
335 	if (count - fl)
336 		failed = copy_to_user(buff + fl, lx->lx_buffer, count - fl);
337 
338 out:
339 	count -= failed;
340 
341 	smp_wmb();
342 	lx->lx_read = (lx->lx_read + count) % lx->buffer_size;
343 	smp_wmb();
344 	mutex_unlock(&channel_wqs[index].mutex);
345 
346 	return count;
347 }
348 
349 ssize_t rtlx_write(int index, const void __user *buffer, size_t count)
350 {
351 	struct rtlx_channel *rt;
352 	unsigned long failed;
353 	size_t rt_read;
354 	size_t fl;
355 
356 	if (rtlx == NULL)
357 		return(-ENOSYS);
358 
359 	rt = &rtlx->channel[index];
360 
361 	mutex_lock(&channel_wqs[index].mutex);
362 	smp_rmb();
363 	rt_read = rt->rt_read;
364 
365 	/* total number of bytes to copy */
366 	count = min(count, (size_t)write_spacefree(rt_read, rt->rt_write,
367 							rt->buffer_size));
368 
369 	/* first bit from write pointer to the end of the buffer, or count */
370 	fl = min(count, (size_t) rt->buffer_size - rt->rt_write);
371 
372 	failed = copy_from_user(rt->rt_buffer + rt->rt_write, buffer, fl);
373 	if (failed)
374 		goto out;
375 
376 	/* if there's any left copy to the beginning of the buffer */
377 	if (count - fl) {
378 		failed = copy_from_user(rt->rt_buffer, buffer + fl, count - fl);
379 	}
380 
381 out:
382 	count -= failed;
383 
384 	smp_wmb();
385 	rt->rt_write = (rt->rt_write + count) % rt->buffer_size;
386 	smp_wmb();
387 	mutex_unlock(&channel_wqs[index].mutex);
388 
389 	return count;
390 }
391 
392 
393 static int file_open(struct inode *inode, struct file *filp)
394 {
395 	int minor = iminor(inode);
396 	int err;
397 
398 	lock_kernel();
399 	err = rtlx_open(minor, (filp->f_flags & O_NONBLOCK) ? 0 : 1);
400 	unlock_kernel();
401 	return err;
402 }
403 
404 static int file_release(struct inode *inode, struct file *filp)
405 {
406 	int minor = iminor(inode);
407 
408 	return rtlx_release(minor);
409 }
410 
411 static unsigned int file_poll(struct file *file, poll_table * wait)
412 {
413 	int minor;
414 	unsigned int mask = 0;
415 
416 	minor = iminor(file->f_path.dentry->d_inode);
417 
418 	poll_wait(file, &channel_wqs[minor].rt_queue, wait);
419 	poll_wait(file, &channel_wqs[minor].lx_queue, wait);
420 
421 	if (rtlx == NULL)
422 		return 0;
423 
424 	/* data available to read? */
425 	if (rtlx_read_poll(minor, 0))
426 		mask |= POLLIN | POLLRDNORM;
427 
428 	/* space to write */
429 	if (rtlx_write_poll(minor))
430 		mask |= POLLOUT | POLLWRNORM;
431 
432 	return mask;
433 }
434 
435 static ssize_t file_read(struct file *file, char __user * buffer, size_t count,
436 			 loff_t * ppos)
437 {
438 	int minor = iminor(file->f_path.dentry->d_inode);
439 
440 	/* data available? */
441 	if (!rtlx_read_poll(minor, (file->f_flags & O_NONBLOCK) ? 0 : 1)) {
442 		return 0;	// -EAGAIN makes cat whinge
443 	}
444 
445 	return rtlx_read(minor, buffer, count);
446 }
447 
448 static ssize_t file_write(struct file *file, const char __user * buffer,
449 			  size_t count, loff_t * ppos)
450 {
451 	int minor;
452 	struct rtlx_channel *rt;
453 
454 	minor = iminor(file->f_path.dentry->d_inode);
455 	rt = &rtlx->channel[minor];
456 
457 	/* any space left... */
458 	if (!rtlx_write_poll(minor)) {
459 		int ret = 0;
460 
461 		if (file->f_flags & O_NONBLOCK)
462 			return -EAGAIN;
463 
464 		__wait_event_interruptible(channel_wqs[minor].rt_queue,
465 		                           rtlx_write_poll(minor),
466 		                           ret);
467 		if (ret)
468 			return ret;
469 	}
470 
471 	return rtlx_write(minor, buffer, count);
472 }
473 
474 static const struct file_operations rtlx_fops = {
475 	.owner =   THIS_MODULE,
476 	.open =    file_open,
477 	.release = file_release,
478 	.write =   file_write,
479 	.read =    file_read,
480 	.poll =    file_poll
481 };
482 
483 static struct irqaction rtlx_irq = {
484 	.handler	= rtlx_interrupt,
485 	.flags		= IRQF_DISABLED,
486 	.name		= "RTLX",
487 };
488 
489 static int rtlx_irq_num = MIPS_CPU_IRQ_BASE + MIPS_CPU_RTLX_IRQ;
490 
491 static char register_chrdev_failed[] __initdata =
492 	KERN_ERR "rtlx_module_init: unable to register device\n";
493 
494 static int __init rtlx_module_init(void)
495 {
496 	struct device *dev;
497 	int i, err;
498 
499 	if (!cpu_has_mipsmt) {
500 		printk("VPE loader: not a MIPS MT capable processor\n");
501 		return -ENODEV;
502 	}
503 
504 	if (tclimit == 0) {
505 		printk(KERN_WARNING "No TCs reserved for AP/SP, not "
506 		       "initializing RTLX.\nPass maxtcs=<n> argument as kernel "
507 		       "argument\n");
508 
509 		return -ENODEV;
510 	}
511 
512 	major = register_chrdev(0, module_name, &rtlx_fops);
513 	if (major < 0) {
514 		printk(register_chrdev_failed);
515 		return major;
516 	}
517 
518 	/* initialise the wait queues */
519 	for (i = 0; i < RTLX_CHANNELS; i++) {
520 		init_waitqueue_head(&channel_wqs[i].rt_queue);
521 		init_waitqueue_head(&channel_wqs[i].lx_queue);
522 		atomic_set(&channel_wqs[i].in_open, 0);
523 		mutex_init(&channel_wqs[i].mutex);
524 
525 		dev = device_create(mt_class, NULL, MKDEV(major, i), NULL,
526 				    "%s%d", module_name, i);
527 		if (IS_ERR(dev)) {
528 			err = PTR_ERR(dev);
529 			goto out_chrdev;
530 		}
531 	}
532 
533 	/* set up notifiers */
534 	notify.start = starting;
535 	notify.stop = stopping;
536 	vpe_notify(tclimit, &notify);
537 
538 	if (cpu_has_vint)
539 		set_vi_handler(MIPS_CPU_RTLX_IRQ, rtlx_dispatch);
540 	else {
541 		pr_err("APRP RTLX init on non-vectored-interrupt processor\n");
542 		err = -ENODEV;
543 		goto out_chrdev;
544 	}
545 
546 	rtlx_irq.dev_id = rtlx;
547 	setup_irq(rtlx_irq_num, &rtlx_irq);
548 
549 	return 0;
550 
551 out_chrdev:
552 	for (i = 0; i < RTLX_CHANNELS; i++)
553 		device_destroy(mt_class, MKDEV(major, i));
554 
555 	return err;
556 }
557 
558 static void __exit rtlx_module_exit(void)
559 {
560 	int i;
561 
562 	for (i = 0; i < RTLX_CHANNELS; i++)
563 		device_destroy(mt_class, MKDEV(major, i));
564 
565 	unregister_chrdev(major, module_name);
566 }
567 
568 module_init(rtlx_module_init);
569 module_exit(rtlx_module_exit);
570 
571 MODULE_DESCRIPTION("MIPS RTLX");
572 MODULE_AUTHOR("Elizabeth Oldham, MIPS Technologies, Inc.");
573 MODULE_LICENSE("GPL");
574