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/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");