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