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/kernel.h>
  21 #include <linux/module.h>
  22 #include <linux/fs.h>
  23 #include <linux/init.h>
  24 #include <asm/uaccess.h>
  25 #include <linux/slab.h>
  26 #include <linux/list.h>
  27 #include <linux/vmalloc.h>
  28 #include <linux/elf.h>
  29 #include <linux/seq_file.h>
  30 #include <linux/syscalls.h>
  31 #include <linux/moduleloader.h>
  32 #include <linux/interrupt.h>
  33 #include <linux/poll.h>
  34 #include <linux/sched.h>
  35 #include <linux/wait.h>
  36 #include <asm/mipsmtregs.h>
  37 #include <asm/cacheflush.h>
  38 #include <asm/atomic.h>
  39 #include <asm/cpu.h>
  40 #include <asm/processor.h>
  41 #include <asm/system.h>
  42 #include <asm/vpe.h>
  43 #include <asm/rtlx.h>
  44
  45 #define RTLX_TARG_VPE 1
  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         int in_open;
  55 } channel_wqs[RTLX_CHANNELS];
  56
  57 static struct irqaction irq;
  58 static int irq_num;
  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(struct pt_regs *regs)
  65 {
  66         do_IRQ(MIPSCPU_INT_BASE + MIPS_CPU_RTLX_IRQ, regs);
  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, struct pt_regs *regs)
  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 __attribute_used__ void 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%x\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         int ret;
 148         struct rtlx_channel *chan;
 149         volatile struct rtlx_info **p;
 150
 151         if (index >= RTLX_CHANNELS) {
 152                 printk(KERN_DEBUG "rtlx_open index out of range\n");
 153                 return -ENOSYS;
 154         }
 155
 156         if (channel_wqs[index].in_open) {
 157                 printk(KERN_DEBUG "rtlx_open channel %d already opened\n", index);
 158                 return -EBUSY;
 159         }
 160
 161         channel_wqs[index].in_open++;
 162
 163         if (rtlx == NULL) {
 164                 if( (p = vpe_get_shared(RTLX_TARG_VPE)) == NULL) {
 165                         if (can_sleep) {
 166                                 DECLARE_WAITQUEUE(wait, current);
 167
 168                                 /* go to sleep */
 169                                 add_wait_queue(&channel_wqs[index].lx_queue, &wait);
 170
 171                                 set_current_state(TASK_INTERRUPTIBLE);
 172                                 while ((p = vpe_get_shared(RTLX_TARG_VPE)) == NULL) {
 173                                         schedule();
 174                                         set_current_state(TASK_INTERRUPTIBLE);
 175                                 }
 176
 177                                 set_current_state(TASK_RUNNING);
 178                                 remove_wait_queue(&channel_wqs[index].lx_queue, &wait);
 179
 180                                 /* back running */
 181                         } else {
 182                                 printk( KERN_DEBUG "No SP program loaded, and device "
 183                                         "opened with O_NONBLOCK\n");
 184                                 channel_wqs[index].in_open = 0;
 185                                 return -ENOSYS;
 186                         }
 187                 }
 188
 189                 if (*p == NULL) {
 190                         if (can_sleep) {
 191                                 DECLARE_WAITQUEUE(wait, current);
 192
 193                                 /* go to sleep */
 194                                 add_wait_queue(&channel_wqs[index].lx_queue, &wait);
 195
 196                                 set_current_state(TASK_INTERRUPTIBLE);
 197                                 while (*p == NULL) {
 198                                         schedule();
 199
 200                                         /* reset task state to interruptable otherwise
 201                                            we'll whizz round here like a very fast loopy
 202                                            thing. schedule() appears to return with state
 203                                            set to TASK_RUNNING.
 204
 205                                            If the loaded SP program, for whatever reason,
 206                                            doesn't set up the shared structure *p will never
 207                                            become true. So whoever connected to either /dev/rt?
 208                                            or if it was kspd, will then take up rather a lot of
 209                                            processor cycles.
 210                                         */
 211
 212                                         set_current_state(TASK_INTERRUPTIBLE);
 213                                 }
 214
 215                                 set_current_state(TASK_RUNNING);
 216                                 remove_wait_queue(&channel_wqs[index].lx_queue, &wait);
 217
 218                                 /* back running */
 219                         }
 220                         else {
 221                                 printk(" *vpe_get_shared is NULL. "
 222                                        "Has an SP program been loaded?\n");
 223                                 channel_wqs[index].in_open = 0;
 224                                 return -ENOSYS;
 225                         }
 226                 }
 227
 228                 if ((unsigned int)*p < KSEG0) {
 229                         printk(KERN_WARNING "vpe_get_shared returned an invalid pointer "
 230                                "maybe an error code %d\n", (int)*p);
 231                         channel_wqs[index].in_open = 0;
 232                         return -ENOSYS;
 233                 }
 234
 235                 if ((ret = rtlx_init(*p)) < 0) {
 236                         channel_wqs[index].in_open = 0;
 237                         return ret;
 238                 }
 239         }
 240
 241         chan = &rtlx->channel[index];
 242
 243         if (chan->lx_state == RTLX_STATE_OPENED) {
 244                 channel_wqs[index].in_open = 0;
 245                 return -EBUSY;
 246         }
 247
 248         chan->lx_state = RTLX_STATE_OPENED;
 249         channel_wqs[index].in_open = 0;
 250         return 0;
 251 }
 252
 253 int rtlx_release(int index)
 254 {
 255         rtlx->channel[index].lx_state = RTLX_STATE_UNUSED;
 256         return 0;
 257 }
 258
 259 unsigned int rtlx_read_poll(int index, int can_sleep)
 260 {
 261         struct rtlx_channel *chan;
 262
 263         if (rtlx == NULL)
 264                 return 0;
 265
 266         chan = &rtlx->channel[index];
 267
 268         /* data available to read? */
 269         if (chan->lx_read == chan->lx_write) {
 270                 if (can_sleep) {
 271                         DECLARE_WAITQUEUE(wait, current);
 272
 273                         /* go to sleep */
 274                         add_wait_queue(&channel_wqs[index].lx_queue, &wait);
 275
 276                         set_current_state(TASK_INTERRUPTIBLE);
 277                         while (chan->lx_read == chan->lx_write) {
 278                                 schedule();
 279
 280                                 set_current_state(TASK_INTERRUPTIBLE);
 281
 282                                 if (sp_stopping) {
 283                                         set_current_state(TASK_RUNNING);
 284                                         remove_wait_queue(&channel_wqs[index].lx_queue, &wait);
 285                                         return 0;
 286                                 }
 287                         }
 288
 289                         set_current_state(TASK_RUNNING);
 290                         remove_wait_queue(&channel_wqs[index].lx_queue, &wait);
 291
 292                         /* back running */
 293                 }
 294                 else
 295                         return 0;
 296         }
 297
 298         return (chan->lx_write + chan->buffer_size - chan->lx_read)
 299                % chan->buffer_size;
 300 }
 301
 302 static inline int write_spacefree(int read, int write, int size)
 303 {
 304         if (read == write) {
 305                 /*
 306                  * Never fill the buffer completely, so indexes are always
 307                  * equal if empty and only empty, or !equal if data available
 308                  */
 309                 return size - 1;
 310         }
 311
 312         return ((read + size - write) % size) - 1;
 313 }
 314
 315 unsigned int rtlx_write_poll(int index)
 316 {
 317         struct rtlx_channel *chan = &rtlx->channel[index];
 318         return write_spacefree(chan->rt_read, chan->rt_write, chan->buffer_size);
 319 }
 320
 321 static inline void copy_to(void *dst, void *src, size_t count, int user)
 322 {
 323         if (user)
 324                 copy_to_user(dst, src, count);
 325         else
 326                 memcpy(dst, src, count);
 327 }
 328
 329 static inline void copy_from(void *dst, void *src, size_t count, int user)
 330 {
 331         if (user)
 332                 copy_from_user(dst, src, count);
 333         else
 334                 memcpy(dst, src, count);
 335 }
 336
 337 ssize_t rtlx_read(int index, void *buff, size_t count, int user)
 338 {
 339         size_t fl = 0L;
 340         struct rtlx_channel *lx;
 341
 342         if (rtlx == NULL)
 343                 return -ENOSYS;
 344
 345         lx = &rtlx->channel[index];
 346
 347         /* find out how much in total */
 348         count = min(count,
 349                      (size_t)(lx->lx_write + lx->buffer_size - lx->lx_read)
 350                      % lx->buffer_size);
 351
 352         /* then how much from the read pointer onwards */
 353         fl = min( count, (size_t)lx->buffer_size - lx->lx_read);
 354
 355         copy_to(buff, &lx->lx_buffer[lx->lx_read], fl, user);
 356
 357         /* and if there is anything left at the beginning of the buffer */
 358         if ( count - fl )
 359                 copy_to (buff + fl, lx->lx_buffer, count - fl, user);
 360
 361         /* update the index */
 362         lx->lx_read += count;
 363         lx->lx_read %= lx->buffer_size;
 364
 365         return count;
 366 }
 367
 368 ssize_t rtlx_write(int index, void *buffer, size_t count, int user)
 369 {
 370         struct rtlx_channel *rt;
 371         size_t fl;
 372
 373         if (rtlx == NULL)
 374                 return(-ENOSYS);
 375
 376         rt = &rtlx->channel[index];
 377
 378         /* total number of bytes to copy */
 379         count = min(count,
 380                     (size_t)write_spacefree(rt->rt_read, rt->rt_write,
 381                                             rt->buffer_size));
 382
 383         /* first bit from write pointer to the end of the buffer, or count */
 384         fl = min(count, (size_t) rt->buffer_size - rt->rt_write);
 385
 386         copy_from (&rt->rt_buffer[rt->rt_write], buffer, fl, user);
 387
 388         /* if there's any left copy to the beginning of the buffer */
 389         if( count - fl )
 390                 copy_from (rt->rt_buffer, buffer + fl, count - fl, user);
 391
 392         rt->rt_write += count;
 393         rt->rt_write %= rt->buffer_size;
 394
 395         return(count);
 396 }
 397
 398
 399 static int file_open(struct inode *inode, struct file *filp)
 400 {
 401         int minor = iminor(inode);
 402
 403         return rtlx_open(minor, (filp->f_flags & O_NONBLOCK) ? 0 : 1);
 404 }
 405
 406 static int file_release(struct inode *inode, struct file *filp)
 407 {
 408         int minor = iminor(inode);
 409
 410         return rtlx_release(minor);
 411 }
 412
 413 static unsigned int file_poll(struct file *file, poll_table * wait)
 414 {
 415         int minor;
 416         unsigned int mask = 0;
 417
 418         minor = iminor(file->f_dentry->d_inode);
 419
 420         poll_wait(file, &channel_wqs[minor].rt_queue, wait);
 421         poll_wait(file, &channel_wqs[minor].lx_queue, wait);
 422
 423         if (rtlx == NULL)
 424                 return 0;
 425
 426         /* data available to read? */
 427         if (rtlx_read_poll(minor, 0))
 428                 mask |= POLLIN | POLLRDNORM;
 429
 430         /* space to write */
 431         if (rtlx_write_poll(minor))
 432                 mask |= POLLOUT | POLLWRNORM;
 433
 434         return mask;
 435 }
 436
 437 static ssize_t file_read(struct file *file, char __user * buffer, size_t count,
 438                          loff_t * ppos)
 439 {
 440         int minor = iminor(file->f_dentry->d_inode);
 441
 442         /* data available? */
 443         if (!rtlx_read_poll(minor, (file->f_flags & O_NONBLOCK) ? 0 : 1)) {
 444                 return 0;       // -EAGAIN makes cat whinge
 445         }
 446
 447         return rtlx_read(minor, buffer, count, 1);
 448 }
 449
 450 static ssize_t file_write(struct file *file, const char __user * buffer,
 451                           size_t count, loff_t * ppos)
 452 {
 453         int minor;
 454         struct rtlx_channel *rt;
 455         DECLARE_WAITQUEUE(wait, current);
 456
 457         minor = iminor(file->f_dentry->d_inode);
 458         rt = &rtlx->channel[minor];
 459
 460         /* any space left... */
 461         if (!rtlx_write_poll(minor)) {
 462
 463                 if (file->f_flags & O_NONBLOCK)
 464                         return -EAGAIN;
 465
 466                 add_wait_queue(&channel_wqs[minor].rt_queue, &wait);
 467                 set_current_state(TASK_INTERRUPTIBLE);
 468
 469                 while (!rtlx_write_poll(minor))
 470                         schedule();
 471
 472                 set_current_state(TASK_RUNNING);
 473                 remove_wait_queue(&channel_wqs[minor].rt_queue, &wait);
 474         }
 475
 476         return rtlx_write(minor, (void *)buffer, count, 1);
 477 }
 478
 479 static struct file_operations rtlx_fops = {
 480         .owner =   THIS_MODULE,
 481         .open =    file_open,
 482         .release = file_release,
 483         .write =   file_write,
 484         .read =    file_read,
 485         .poll =    file_poll
 486 };
 487
 488 static struct irqaction rtlx_irq = {
 489         .handler        = rtlx_interrupt,
 490         .flags          = IRQF_DISABLED,
 491         .name           = "RTLX",
 492 };
 493
 494 static int rtlx_irq_num = MIPSCPU_INT_BASE + MIPS_CPU_RTLX_IRQ;
 495
 496 static char register_chrdev_failed[] __initdata =
 497         KERN_ERR "rtlx_module_init: unable to register device\n";
 498
 499 static int rtlx_module_init(void)
 500 {
 501         int i;
 502
 503         major = register_chrdev(0, module_name, &rtlx_fops);
 504         if (major < 0) {
 505                 printk(register_chrdev_failed);
 506                 return major;
 507         }
 508
 509         /* initialise the wait queues */
 510         for (i = 0; i < RTLX_CHANNELS; i++) {
 511                 init_waitqueue_head(&channel_wqs[i].rt_queue);
 512                 init_waitqueue_head(&channel_wqs[i].lx_queue);
 513                 channel_wqs[i].in_open = 0;
 514         }
 515
 516         /* set up notifiers */
 517         notify.start = starting;
 518         notify.stop = stopping;
 519         vpe_notify(RTLX_TARG_VPE, &notify);
 520
 521         if (cpu_has_vint)
 522                 set_vi_handler(MIPS_CPU_RTLX_IRQ, rtlx_dispatch);
 523
 524         rtlx_irq.dev_id = rtlx;
 525         setup_irq(rtlx_irq_num, &rtlx_irq);
 526
 527         return 0;
 528 }
 529
 530 static void __exit rtlx_module_exit(void)
 531 {
 532         unregister_chrdev(major, module_name);
 533 }
 534
 535 module_init(rtlx_module_init);
 536 module_exit(rtlx_module_exit);
 537
 538 MODULE_DESCRIPTION("MIPS RTLX");
 539 MODULE_AUTHOR("Elizabeth Oldham, MIPS Technologies, Inc.");
 540 MODULE_LICENSE("GPL");