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/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_drvdata(mt_class, NULL, MKDEV(major, i),
 526                                             NULL, "%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");