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