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