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