arch/mips/kernel/rtlx.c

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