arch/mips/kernel/rtlx.c

   1 /*
   2  * This file is subject to the terms and conditions of the GNU General Public
   3  * License.  See the file "COPYING" in the main directory of this archive
   4  * for more details.
   5  *
   6  * Copyright (C) 2005 MIPS Technologies, Inc.  All rights reserved.
   7  * Copyright (C) 2005, 06 Ralf Baechle (ralf@linux-mips.org)
   8  * Copyright (C) 2013 Imagination Technologies Ltd.
   9  */
  10 #include <linux/kernel.h>
  11 #include <linux/fs.h>
  12 #include <linux/syscalls.h>
  13 #include <linux/moduleloader.h>
  14 #include <linux/atomic.h>
  15 #include <linux/sched/signal.h>
  16
  17 #include <asm/mipsmtregs.h>
  18 #include <asm/mips_mt.h>
  19 #include <asm/processor.h>
  20 #include <asm/rtlx.h>
  21 #include <asm/setup.h>
  22 #include <asm/vpe.h>
  23
  24 static int sp_stopping;
  25 struct rtlx_info *rtlx;
  26 struct chan_waitqueues channel_wqs[RTLX_CHANNELS];
  27 struct vpe_notifications rtlx_notify;
  28 void (*aprp_hook)(void) = NULL;
  29 EXPORT_SYMBOL(aprp_hook);
  30
  31 static void __used dump_rtlx(void)
  32 {
  33         int i;
  34
  35         pr_info("id 0x%lx state %d\n", rtlx->id, rtlx->state);
  36
  37         for (i = 0; i < RTLX_CHANNELS; i++) {
  38                 struct rtlx_channel *chan = &rtlx->channel[i];
  39
  40                 pr_info(" rt_state %d lx_state %d buffer_size %d\n",
  41                         chan->rt_state, chan->lx_state, chan->buffer_size);
  42
  43                 pr_info(" rt_read %d rt_write %d\n",
  44                         chan->rt_read, chan->rt_write);
  45
  46                 pr_info(" lx_read %d lx_write %d\n",
  47                         chan->lx_read, chan->lx_write);
  48
  49                 pr_info(" rt_buffer <%s>\n", chan->rt_buffer);
  50                 pr_info(" lx_buffer <%s>\n", chan->lx_buffer);
  51         }
  52 }
  53
  54 /* call when we have the address of the shared structure from the SP side. */
  55 static int rtlx_init(struct rtlx_info *rtlxi)
  56 {
  57         if (rtlxi->id != RTLX_ID) {
  58                 pr_err("no valid RTLX id at 0x%p 0x%lx\n", rtlxi, rtlxi->id);
  59                 return -ENOEXEC;
  60         }
  61
  62         rtlx = rtlxi;
  63
  64         return 0;
  65 }
  66
  67 /* notifications */
  68 void rtlx_starting(int vpe)
  69 {
  70         int i;
  71         sp_stopping = 0;
  72
  73         /* force a reload of rtlx */
  74         rtlx = NULL;
  75
  76         /* wake up any sleeping rtlx_open's */
  77         for (i = 0; i < RTLX_CHANNELS; i++)
  78                 wake_up_interruptible(&channel_wqs[i].lx_queue);
  79 }
  80
  81 void rtlx_stopping(int vpe)
  82 {
  83         int i;
  84
  85         sp_stopping = 1;
  86         for (i = 0; i < RTLX_CHANNELS; i++)
  87                 wake_up_interruptible(&channel_wqs[i].lx_queue);
  88 }
  89
  90
  91 int rtlx_open(int index, int can_sleep)
  92 {
  93         struct rtlx_info **p;
  94         struct rtlx_channel *chan;
  95         enum rtlx_state state;
  96         int ret = 0;
  97
  98         if (index >= RTLX_CHANNELS) {
  99                 pr_debug("rtlx_open index out of range\n");
 100                 return -ENOSYS;
 101         }
 102
 103         if (atomic_inc_return(&channel_wqs[index].in_open) > 1) {
 104                 pr_debug("rtlx_open channel %d already opened\n", index);
 105                 ret = -EBUSY;
 106                 goto out_fail;
 107         }
 108
 109         if (rtlx == NULL) {
 110                 p = vpe_get_shared(aprp_cpu_index());
 111                 if (p == NULL) {
 112                         if (can_sleep) {
 113                                 ret = __wait_event_interruptible(
 114                                         channel_wqs[index].lx_queue,
 115                                         (p = vpe_get_shared(aprp_cpu_index())));
 116                                 if (ret)
 117                                         goto out_fail;
 118                         } else {
 119                                 pr_debug("No SP program loaded, and device opened with O_NONBLOCK\n");
 120                                 ret = -ENOSYS;
 121                                 goto out_fail;
 122                         }
 123                 }
 124
 125                 smp_rmb();
 126                 if (*p == NULL) {
 127                         if (can_sleep) {
 128                                 DEFINE_WAIT(wait);
 129
 130                                 for (;;) {
 131                                         prepare_to_wait(
 132                                                 &channel_wqs[index].lx_queue,
 133                                                 &wait, TASK_INTERRUPTIBLE);
 134                                         smp_rmb();
 135                                         if (*p != NULL)
 136                                                 break;
 137                                         if (!signal_pending(current)) {
 138                                                 schedule();
 139                                                 continue;
 140                                         }
 141                                         ret = -ERESTARTSYS;
 142                                         goto out_fail;
 143                                 }
 144                                 finish_wait(&channel_wqs[index].lx_queue,
 145                                             &wait);
 146                         } else {
 147                                 pr_err(" *vpe_get_shared is NULL. Has an SP program been loaded?\n");
 148                                 ret = -ENOSYS;
 149                                 goto out_fail;
 150                         }
 151                 }
 152
 153                 if ((unsigned int)*p < KSEG0) {
 154                         pr_warn("vpe_get_shared returned an invalid pointer maybe an error code %d\n",
 155                                 (int)*p);
 156                         ret = -ENOSYS;
 157                         goto out_fail;
 158                 }
 159
 160                 ret = rtlx_init(*p);
 161                 if (ret < 0)
 162                         goto out_ret;
 163         }
 164
 165         chan = &rtlx->channel[index];
 166
 167         state = xchg(&chan->lx_state, RTLX_STATE_OPENED);
 168         if (state == RTLX_STATE_OPENED) {
 169                 ret = -EBUSY;
 170                 goto out_fail;
 171         }
 172
 173 out_fail:
 174         smp_mb();
 175         atomic_dec(&channel_wqs[index].in_open);
 176         smp_mb();
 177
 178 out_ret:
 179         return ret;
 180 }
 181
 182 int rtlx_release(int index)
 183 {
 184         if (rtlx == NULL) {
 185                 pr_err("rtlx_release() with null rtlx\n");
 186                 return 0;
 187         }
 188         rtlx->channel[index].lx_state = RTLX_STATE_UNUSED;
 189         return 0;
 190 }
 191
 192 unsigned int rtlx_read_poll(int index, int can_sleep)
 193 {
 194         struct rtlx_channel *chan;
 195
 196         if (rtlx == NULL)
 197                 return 0;
 198
 199         chan = &rtlx->channel[index];
 200
 201         /* data available to read? */
 202         if (chan->lx_read == chan->lx_write) {
 203                 if (can_sleep) {
 204                         int ret = __wait_event_interruptible(
 205                                 channel_wqs[index].lx_queue,
 206                                 (chan->lx_read != chan->lx_write) ||
 207                                 sp_stopping);
 208                         if (ret)
 209                                 return ret;
 210
 211                         if (sp_stopping)
 212                                 return 0;
 213                 } else
 214                         return 0;
 215         }
 216
 217         return (chan->lx_write + chan->buffer_size - chan->lx_read)
 218                % chan->buffer_size;
 219 }
 220
 221 static inline int write_spacefree(int read, int write, int size)
 222 {
 223         if (read == write) {
 224                 /*
 225                  * Never fill the buffer completely, so indexes are always
 226                  * equal if empty and only empty, or !equal if data available
 227                  */
 228                 return size - 1;
 229         }
 230
 231         return ((read + size - write) % size) - 1;
 232 }
 233
 234 unsigned int rtlx_write_poll(int index)
 235 {
 236         struct rtlx_channel *chan = &rtlx->channel[index];
 237
 238         return write_spacefree(chan->rt_read, chan->rt_write,
 239                                 chan->buffer_size);
 240 }
 241
 242 ssize_t rtlx_read(int index, void __user *buff, size_t count)
 243 {
 244         size_t lx_write, fl = 0L;
 245         struct rtlx_channel *lx;
 246         unsigned long failed;
 247
 248         if (rtlx == NULL)
 249                 return -ENOSYS;
 250
 251         lx = &rtlx->channel[index];
 252
 253         mutex_lock(&channel_wqs[index].mutex);
 254         smp_rmb();
 255         lx_write = lx->lx_write;
 256
 257         /* find out how much in total */
 258         count = min(count,
 259                      (size_t)(lx_write + lx->buffer_size - lx->lx_read)
 260                      % lx->buffer_size);
 261
 262         /* then how much from the read pointer onwards */
 263         fl = min(count, (size_t)lx->buffer_size - lx->lx_read);
 264
 265         failed = copy_to_user(buff, lx->lx_buffer + lx->lx_read, fl);
 266         if (failed)
 267                 goto out;
 268
 269         /* and if there is anything left at the beginning of the buffer */
 270         if (count - fl)
 271                 failed = copy_to_user(buff + fl, lx->lx_buffer, count - fl);
 272
 273 out:
 274         count -= failed;
 275
 276         smp_wmb();
 277         lx->lx_read = (lx->lx_read + count) % lx->buffer_size;
 278         smp_wmb();
 279         mutex_unlock(&channel_wqs[index].mutex);
 280
 281         return count;
 282 }
 283
 284 ssize_t rtlx_write(int index, const void __user *buffer, size_t count)
 285 {
 286         struct rtlx_channel *rt;
 287         unsigned long failed;
 288         size_t rt_read;
 289         size_t fl;
 290
 291         if (rtlx == NULL)
 292                 return -ENOSYS;
 293
 294         rt = &rtlx->channel[index];
 295
 296         mutex_lock(&channel_wqs[index].mutex);
 297         smp_rmb();
 298         rt_read = rt->rt_read;
 299
 300         /* total number of bytes to copy */
 301         count = min_t(size_t, count, write_spacefree(rt_read, rt->rt_write,
 302                                                      rt->buffer_size));
 303
 304         /* first bit from write pointer to the end of the buffer, or count */
 305         fl = min(count, (size_t) rt->buffer_size - rt->rt_write);
 306
 307         failed = copy_from_user(rt->rt_buffer + rt->rt_write, buffer, fl);
 308         if (failed)
 309                 goto out;
 310
 311         /* if there's any left copy to the beginning of the buffer */
 312         if (count - fl)
 313                 failed = copy_from_user(rt->rt_buffer, buffer + fl, count - fl);
 314
 315 out:
 316         count -= failed;
 317
 318         smp_wmb();
 319         rt->rt_write = (rt->rt_write + count) % rt->buffer_size;
 320         smp_wmb();
 321         mutex_unlock(&channel_wqs[index].mutex);
 322
 323         _interrupt_sp();
 324
 325         return count;
 326 }
 327
 328
 329 static int file_open(struct inode *inode, struct file *filp)
 330 {
 331         return rtlx_open(iminor(inode), (filp->f_flags & O_NONBLOCK) ? 0 : 1);
 332 }
 333
 334 static int file_release(struct inode *inode, struct file *filp)
 335 {
 336         return rtlx_release(iminor(inode));
 337 }
 338
 339 static __poll_t file_poll(struct file *file, poll_table *wait)
 340 {
 341         int minor = iminor(file_inode(file));
 342         __poll_t mask = 0;
 343
 344         poll_wait(file, &channel_wqs[minor].rt_queue, wait);
 345         poll_wait(file, &channel_wqs[minor].lx_queue, wait);
 346
 347         if (rtlx == NULL)
 348                 return 0;
 349
 350         /* data available to read? */
 351         if (rtlx_read_poll(minor, 0))
 352                 mask |= EPOLLIN | EPOLLRDNORM;
 353
 354         /* space to write */
 355         if (rtlx_write_poll(minor))
 356                 mask |= EPOLLOUT | EPOLLWRNORM;
 357
 358         return mask;
 359 }
 360
 361 static ssize_t file_read(struct file *file, char __user *buffer, size_t count,
 362                          loff_t *ppos)
 363 {
 364         int minor = iminor(file_inode(file));
 365
 366         /* data available? */
 367         if (!rtlx_read_poll(minor, (file->f_flags & O_NONBLOCK) ? 0 : 1))
 368                 return 0;       /* -EAGAIN makes 'cat' whine */
 369
 370         return rtlx_read(minor, buffer, count);
 371 }
 372
 373 static ssize_t file_write(struct file *file, const char __user *buffer,
 374                           size_t count, loff_t *ppos)
 375 {
 376         int minor = iminor(file_inode(file));
 377
 378         /* any space left... */
 379         if (!rtlx_write_poll(minor)) {
 380                 int ret;
 381
 382                 if (file->f_flags & O_NONBLOCK)
 383                         return -EAGAIN;
 384
 385                 ret = __wait_event_interruptible(channel_wqs[minor].rt_queue,
 386                                            rtlx_write_poll(minor));
 387                 if (ret)
 388                         return ret;
 389         }
 390
 391         return rtlx_write(minor, buffer, count);
 392 }
 393
 394 const struct file_operations rtlx_fops = {
 395         .owner =   THIS_MODULE,
 396         .open =    file_open,
 397         .release = file_release,
 398         .write =   file_write,
 399         .read =    file_read,
 400         .poll =    file_poll,
 401         .llseek =  noop_llseek,
 402 };
 403
 404 module_init(rtlx_module_init);
 405 module_exit(rtlx_module_exit);
 406
 407 MODULE_DESCRIPTION("MIPS RTLX");
 408 MODULE_AUTHOR("Elizabeth Oldham, MIPS Technologies, Inc.");
 409 MODULE_LICENSE("GPL");