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