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Linux/arch/mips/kernel/rtlx.c

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

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