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