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 #include <asm/setup.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                         ret = __wait_event_interruptible(
 176                                         channel_wqs[index].lx_queue,
 177                                         (p = vpe_get_shared(tclimit)));
 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 = __wait_event_interruptible(
 268                                 channel_wqs[index].lx_queue,
 269                                 (chan->lx_read != chan->lx_write) ||
 270                                 sp_stopping);
 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 = iminor(file_inode(file));
 404         unsigned int mask = 0;
 405
 406         poll_wait(file, &channel_wqs[minor].rt_queue, wait);
 407         poll_wait(file, &channel_wqs[minor].lx_queue, wait);
 408
 409         if (rtlx == NULL)
 410                 return 0;
 411
 412         /* data available to read? */
 413         if (rtlx_read_poll(minor, 0))
 414                 mask |= POLLIN | POLLRDNORM;
 415
 416         /* space to write */
 417         if (rtlx_write_poll(minor))
 418                 mask |= POLLOUT | POLLWRNORM;
 419
 420         return mask;
 421 }
 422
 423 static ssize_t file_read(struct file *file, char __user * buffer, size_t count,
 424                          loff_t * ppos)
 425 {
 426         int minor = iminor(file_inode(file));
 427
 428         /* data available? */
 429         if (!rtlx_read_poll(minor, (file->f_flags & O_NONBLOCK) ? 0 : 1)) {
 430                 return 0;       // -EAGAIN makes cat whinge
 431         }
 432
 433         return rtlx_read(minor, buffer, count);
 434 }
 435
 436 static ssize_t file_write(struct file *file, const char __user * buffer,
 437                           size_t count, loff_t * ppos)
 438 {
 439         int minor = iminor(file_inode(file));
 440
 441         /* any space left... */
 442         if (!rtlx_write_poll(minor)) {
 443                 int ret;
 444
 445                 if (file->f_flags & O_NONBLOCK)
 446                         return -EAGAIN;
 447
 448                 ret = __wait_event_interruptible(channel_wqs[minor].rt_queue,
 449                                            rtlx_write_poll(minor));
 450                 if (ret)
 451                         return ret;
 452         }
 453
 454         return rtlx_write(minor, buffer, count);
 455 }
 456
 457 static const struct file_operations rtlx_fops = {
 458         .owner =   THIS_MODULE,
 459         .open =    file_open,
 460         .release = file_release,
 461         .write =   file_write,
 462         .read =    file_read,
 463         .poll =    file_poll,
 464         .llseek =  noop_llseek,
 465 };
 466
 467 static struct irqaction rtlx_irq = {
 468         .handler        = rtlx_interrupt,
 469         .name           = "RTLX",
 470 };
 471
 472 static int rtlx_irq_num = MIPS_CPU_IRQ_BASE + MIPS_CPU_RTLX_IRQ;
 473
 474 static char register_chrdev_failed[] __initdata =
 475         KERN_ERR "rtlx_module_init: unable to register device\n";
 476
 477 static int __init rtlx_module_init(void)
 478 {
 479         struct device *dev;
 480         int i, err;
 481
 482         if (!cpu_has_mipsmt) {
 483                 printk("VPE loader: not a MIPS MT capable processor\n");
 484                 return -ENODEV;
 485         }
 486
 487         if (tclimit == 0) {
 488                 printk(KERN_WARNING "No TCs reserved for AP/SP, not "
 489                        "initializing RTLX.\nPass maxtcs=<n> argument as kernel "
 490                        "argument\n");
 491
 492                 return -ENODEV;
 493         }
 494
 495         major = register_chrdev(0, module_name, &rtlx_fops);
 496         if (major < 0) {
 497                 printk(register_chrdev_failed);
 498                 return major;
 499         }
 500
 501         /* initialise the wait queues */
 502         for (i = 0; i < RTLX_CHANNELS; i++) {
 503                 init_waitqueue_head(&channel_wqs[i].rt_queue);
 504                 init_waitqueue_head(&channel_wqs[i].lx_queue);
 505                 atomic_set(&channel_wqs[i].in_open, 0);
 506                 mutex_init(&channel_wqs[i].mutex);
 507
 508                 dev = device_create(mt_class, NULL, MKDEV(major, i), NULL,
 509                                     "%s%d", module_name, i);
 510                 if (IS_ERR(dev)) {
 511                         err = PTR_ERR(dev);
 512                         goto out_chrdev;
 513                 }
 514         }
 515
 516         /* set up notifiers */
 517         notify.start = starting;
 518         notify.stop = stopping;
 519         vpe_notify(tclimit, &notify);
 520
 521         if (cpu_has_vint)
 522                 set_vi_handler(MIPS_CPU_RTLX_IRQ, rtlx_dispatch);
 523         else {
 524                 pr_err("APRP RTLX init on non-vectored-interrupt processor\n");
 525                 err = -ENODEV;
 526                 goto out_chrdev;
 527         }
 528
 529         rtlx_irq.dev_id = rtlx;
 530         setup_irq(rtlx_irq_num, &rtlx_irq);
 531
 532         return 0;
 533
 534 out_chrdev:
 535         for (i = 0; i < RTLX_CHANNELS; i++)
 536                 device_destroy(mt_class, MKDEV(major, i));
 537
 538         return err;
 539 }
 540
 541 static void __exit rtlx_module_exit(void)
 542 {
 543         int i;
 544
 545         for (i = 0; i < RTLX_CHANNELS; i++)
 546                 device_destroy(mt_class, MKDEV(major, i));
 547
 548         unregister_chrdev(major, module_name);
 549 }
 550
 551 module_init(rtlx_module_init);
 552 module_exit(rtlx_module_exit);
 553
 554 MODULE_DESCRIPTION("MIPS RTLX");
 555 MODULE_AUTHOR("Elizabeth Oldham, MIPS Technologies, Inc.");
 556 MODULE_LICENSE("GPL");