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