arch/arm/mach-sa1100/dma-sa1100.c

   1 /*
   2  * arch/arm/kernel/dma-sa1100.c
   3  *
   4  * Support functions for the SA11x0 internal DMA channels.
   5  * (see also Documentation/arm/SA1100/DMA)
   6  *
   7  * Copyright (C) 2000 Nicolas Pitre
   8  *
   9  * This program is free software; you can redistribute it and/or modify
  10  * it under the terms of the GNU General Public License version 2 as
  11  * published by the Free Software Foundation.
  12  *
  13  */
  14
  15 #include <linux/module.h>
  16 #include <linux/init.h>
  17 #include <linux/sched.h>
  18 #include <linux/spinlock.h>
  19 #include <linux/slab.h>
  20 #include <linux/errno.h>
  21
  22 #include <asm/system.h>
  23 #include <asm/irq.h>
  24 #include <asm/hardware.h>
  25 #include <asm/io.h>
  26 #include <asm/dma.h>
  27 #include <asm/mach/dma.h>
  28
  29
  30 #undef DEBUG
  31 #ifdef DEBUG
  32 #define DPRINTK( s, arg... )  printk( "dma<%s>: " s, dma->device_id , ##arg )
  33 #else
  34 #define DPRINTK( x... )
  35 #endif
  36
  37
  38 /*
  39  * DMA control register structure
  40  */
  41 typedef struct {
  42         volatile u_long DDAR;
  43         volatile u_long SetDCSR;
  44         volatile u_long ClrDCSR;
  45         volatile u_long RdDCSR;
  46         volatile dma_addr_t DBSA;
  47         volatile u_long DBTA;
  48         volatile dma_addr_t DBSB;
  49         volatile u_long DBTB;
  50 } dma_regs_t;
  51
  52 #include "dma.h"
  53
  54 sa1100_dma_t dma_chan[MAX_SA1100_DMA_CHANNELS];
  55
  56 /*
  57  * Maximum physical DMA buffer size
  58  */
  59 #define MAX_DMA_SIZE            0x1fff
  60 #define MAX_DMA_ORDER           12
  61
  62
  63 /*
  64  * DMA processing...
  65  */
  66
  67 static inline int start_sa1100_dma(sa1100_dma_t * dma, dma_addr_t dma_ptr, int size)
  68 {
  69         dma_regs_t *regs = dma->regs;
  70         int status;
  71
  72         status = regs->RdDCSR;
  73
  74         /* If both DMA buffers are started, there's nothing else we can do. */
  75         if ((status & (DCSR_STRTA | DCSR_STRTB)) == (DCSR_STRTA | DCSR_STRTB)) {
  76                 DPRINTK("start: st %#x busy\n", status);
  77                 return -EBUSY;
  78         }
  79
  80         if (((status & DCSR_BIU) && (status & DCSR_STRTB)) ||
  81             (!(status & DCSR_BIU) && !(status & DCSR_STRTA))) {
  82                 if (status & DCSR_DONEA) {
  83                         /* give a chance for the interrupt to be processed */
  84                         goto irq_pending;
  85                 }
  86                 regs->DBSA = dma_ptr;
  87                 regs->DBTA = size;
  88                 regs->SetDCSR = DCSR_STRTA | DCSR_IE | DCSR_RUN;
  89                 DPRINTK("start a=%#x s=%d on A\n", dma_ptr, size);
  90         } else {
  91                 if (status & DCSR_DONEB) {
  92                         /* give a chance for the interrupt to be processed */
  93                         goto irq_pending;
  94                 }
  95                 regs->DBSB = dma_ptr;
  96                 regs->DBTB = size;
  97                 regs->SetDCSR = DCSR_STRTB | DCSR_IE | DCSR_RUN;
  98                 DPRINTK("start a=%#x s=%d on B\n", dma_ptr, size);
  99         }
 100
 101         return 0;
 102
 103 irq_pending:
 104         return -EAGAIN;
 105 }
 106
 107
 108 static int start_dma(sa1100_dma_t *dma, dma_addr_t dma_ptr, int size)
 109 {
 110         if (channel_is_sa1111_sac(dma - dma_chan))
 111                 return start_sa1111_sac_dma(dma, dma_ptr, size);
 112         return start_sa1100_dma(dma, dma_ptr, size);
 113 }
 114
 115
 116 /* This must be called with IRQ disabled */
 117 static void process_dma(sa1100_dma_t * dma)
 118 {
 119         dma_buf_t *buf;
 120         int chunksize;
 121
 122         for (;;) {
 123                 buf = dma->tail;
 124
 125                 if (!buf || dma->stopped) {
 126                         /* no more data available */
 127                         DPRINTK("process: no more buf (dma %s)\n",
 128                                 dma->curr ? "active" : "inactive");
 129                         /*
 130                          * Some devices may require DMA still sending data
 131                          * at any time for clock reference, etc.
 132                          * Note: if there is still a data buffer being
 133                          * processed then the ref count is negative.  This
 134                          * allows for the DMA termination to be accounted in
 135                          * the proper order.
 136                          */
 137                         if (dma->spin_size && dma->spin_ref >= 0) {
 138                                 chunksize = dma->spin_size;
 139                                 if (chunksize > MAX_DMA_SIZE)
 140                                         chunksize = (1 << MAX_DMA_ORDER);
 141                                 while (start_dma(dma, dma->spin_addr, chunksize) == 0)
 142                                         dma->spin_ref++;
 143                                 if (dma->curr != NULL)
 144                                         dma->spin_ref = -dma->spin_ref;
 145                         }
 146                         break;
 147                 }
 148
 149                 /*
 150                  * This improves latency if there are some active spinning
 151                  * buffers.  We kill them altogether.
 152                  */
 153                 if (dma->spin_ref > 0) {
 154                         if (channel_is_sa1111_sac(dma - dma_chan))
 155                                 sa1111_reset_sac_dma(dma - dma_chan);
 156                         else
 157                                 dma->regs->ClrDCSR =
 158                                     DCSR_STRTA|DCSR_STRTB|DCSR_DONEA|DCSR_DONEB;
 159                         dma->spin_ref = 0;
 160                 }
 161
 162                 /*
 163                  * Let's try to start DMA on the current buffer.
 164                  * If DMA is busy then we break here.
 165                  */
 166                 chunksize = buf->size;
 167                 if (chunksize > MAX_DMA_SIZE)
 168                         chunksize = (1 << MAX_DMA_ORDER);
 169                 DPRINTK("process: b=%#x s=%d\n", (int) buf->id, buf->size);
 170                 if (start_dma(dma, buf->dma_ptr, chunksize) != 0)
 171                         break;
 172                 if (!dma->curr)
 173                         dma->curr = buf;
 174                 buf->ref++;
 175                 buf->dma_ptr += chunksize;
 176                 buf->size -= chunksize;
 177                 if (buf->size == 0) {
 178                         /* current buffer is done: move tail to the next one */
 179                         dma->tail = buf->next;
 180                         DPRINTK("process: next b=%#x\n", (int) dma->tail);
 181                 }
 182         }
 183 }
 184
 185
 186 /* This must be called with IRQ disabled */
 187 void sa1100_dma_done (sa1100_dma_t *dma)
 188 {
 189         dma_buf_t *buf = dma->curr;
 190
 191         if (dma->spin_ref > 0) {
 192                 dma->spin_ref--;
 193         } else if (buf) {
 194                 buf->ref--;
 195                 if (buf->ref == 0 && buf->size == 0) {
 196                         /*
 197                          * Current buffer is done.
 198                          * Move current reference to the next one and send
 199                          * the processed buffer to the callback function,
 200                          * then discard it.
 201                          */
 202                         DPRINTK("IRQ: buf done\n");
 203                         dma->curr = buf->next;
 204                         dma->spin_ref = -dma->spin_ref;
 205                         if (dma->head == buf)
 206                                 dma->head = NULL;
 207                         if (dma->callback) {
 208                                 int size = buf->dma_ptr - buf->dma_start;
 209                                 dma->callback(buf->id, size);
 210                         }
 211                         kfree(buf);
 212                 }
 213         }
 214
 215         process_dma(dma);
 216 }
 217
 218
 219 static void dma_irq_handler(int irq, void *dev_id, struct pt_regs *regs)
 220 {
 221         sa1100_dma_t *dma = (sa1100_dma_t *) dev_id;
 222         int status = dma->regs->RdDCSR;
 223
 224         DPRINTK("IRQ: b=%#x st=%#x\n", (int) dma->curr->id, status);
 225
 226         if (status & (DCSR_ERROR)) {
 227                 printk(KERN_ERR "DMA on \"%s\" caused an error\n", dma->device_id);
 228                 dma->regs->ClrDCSR = DCSR_ERROR;
 229         }
 230
 231         dma->regs->ClrDCSR = status & (DCSR_DONEA | DCSR_DONEB);
 232         if (status & DCSR_DONEA)
 233                 sa1100_dma_done (dma);
 234         if (status & DCSR_DONEB)
 235                 sa1100_dma_done (dma);
 236 }
 237
 238
 239 /*
 240  * DMA interface functions
 241  */
 242
 243 static spinlock_t dma_list_lock;
 244
 245 int sa1100_request_dma (dmach_t * channel, const char *device_id,
 246                         dma_device_t device)
 247 {
 248         sa1100_dma_t *dma = NULL;
 249         dma_regs_t *regs;
 250         int i, err;
 251
 252         *channel = -1;          /* to be sure we catch the freeing of a misregistered channel */
 253
 254         err = 0;
 255         spin_lock(&dma_list_lock);
 256         for (i = 0; i < SA1100_DMA_CHANNELS; i++) {
 257                 if (dma_chan[i].in_use) {
 258                         if (dma_chan[i].device == device) {
 259                                 err = -EBUSY;
 260                                 break;
 261                         }
 262                 } else if (!dma) {
 263                         dma = &dma_chan[i];
 264                 }
 265         }
 266         if (!err) {
 267                if (dma)
 268                        dma->in_use = 1;
 269                else
 270                        err = -ENOSR;
 271         }
 272         spin_unlock(&dma_list_lock);
 273         if (err)
 274                 return err;
 275
 276         err = request_irq(dma->irq, dma_irq_handler, SA_INTERRUPT,
 277                           device_id, (void *) dma);
 278         if (err) {
 279                 printk(KERN_ERR
 280                        "%s: unable to request IRQ %d for DMA channel\n",
 281                        device_id, dma->irq);
 282                 return err;
 283         }
 284
 285         *channel = dma - dma_chan;
 286         dma->device_id = device_id;
 287         dma->device = device;
 288         dma->callback = NULL;
 289         dma->spin_size = 0;
 290
 291         regs = dma->regs;
 292         regs->ClrDCSR =
 293                 (DCSR_DONEA | DCSR_DONEB | DCSR_STRTA | DCSR_STRTB |
 294                  DCSR_IE | DCSR_ERROR | DCSR_RUN);
 295         regs->DDAR = device;
 296         DPRINTK("requested\n");
 297         return 0;
 298 }
 299
 300
 301 int sa1100_dma_set_callback(dmach_t channel, dma_callback_t cb)
 302 {
 303         sa1100_dma_t *dma = &dma_chan[channel];
 304
 305         if ((unsigned)channel >= MAX_SA1100_DMA_CHANNELS || !dma->in_use)
 306                 return -EINVAL;
 307
 308         dma->callback = cb;
 309         DPRINTK("cb = %p\n", cb);
 310         return 0;
 311 }
 312
 313
 314 int sa1100_dma_set_spin(dmach_t channel, dma_addr_t addr, int size)
 315 {
 316         sa1100_dma_t *dma = &dma_chan[channel];
 317         int flags;
 318
 319         if ((unsigned)channel >= MAX_SA1100_DMA_CHANNELS || !dma->in_use)
 320                 return -EINVAL;
 321
 322         DPRINTK("set spin %d at %#x\n", size, addr);
 323         local_irq_save(flags);
 324         dma->spin_addr = addr;
 325         dma->spin_size = size;
 326         if (size)
 327                 process_dma(dma);
 328         local_irq_restore(flags);
 329         return 0;
 330 }
 331
 332
 333 int sa1100_dma_queue_buffer(dmach_t channel, void *buf_id,
 334                             dma_addr_t data, int size)
 335 {
 336         sa1100_dma_t *dma;
 337         dma_buf_t *buf;
 338         int flags;
 339
 340         dma = &dma_chan[channel];
 341         if ((unsigned)channel >= MAX_SA1100_DMA_CHANNELS || !dma->in_use)
 342                 return -EINVAL;
 343
 344         buf = kmalloc(sizeof(*buf), GFP_ATOMIC);
 345         if (!buf)
 346                 return -ENOMEM;
 347
 348         buf->next = NULL;
 349         buf->ref = 0;
 350         buf->dma_ptr = buf->dma_start = data;
 351         buf->size = size;
 352         buf->id = buf_id;
 353         DPRINTK("queueing b=%#x a=%#x s=%d\n", (int) buf_id, data, size);
 354
 355         local_irq_save(flags);
 356         if (dma->head)
 357                 dma->head->next = buf;
 358         dma->head = buf;
 359         if (!dma->tail)
 360                 dma->tail = buf;
 361         process_dma(dma);
 362         local_irq_restore(flags);
 363
 364         return 0;
 365 }
 366
 367
 368 int sa1100_dma_get_current(dmach_t channel, void **buf_id, dma_addr_t *addr)
 369 {
 370         sa1100_dma_t *dma = &dma_chan[channel];
 371         dma_regs_t *regs;
 372         int flags, ret;
 373
 374         if ((unsigned)channel >= MAX_SA1100_DMA_CHANNELS || !dma->in_use)
 375                 return -EINVAL;
 376
 377         if (channel_is_sa1111_sac(channel))
 378                 return sa1111_dma_get_current(channel, buf_id, addr);
 379
 380         regs = dma->regs;
 381         local_irq_save(flags);
 382         if (dma->curr && dma->spin_ref <= 0) {
 383                 dma_buf_t *buf = dma->curr;
 384                 int status, using_bufa;
 385
 386                 status = regs->RdDCSR;
 387                 /*
 388                  * If we got here, that's because there is, or recently was, a
 389                  * buffer being processed.  We must determine whether buffer
 390                  * A or B is active.  Two possibilities: either we are
 391                  * in the middle of a buffer, or the DMA controller just
 392                  * switched to the next toggle but the interrupt hasn't been
 393                  * serviced yet.  The former case is straight forward.  In
 394                  * the later case, we'll do like if DMA is just at the end
 395                  * of the previous toggle since all registers haven't been
 396                  * reset yet.  This goes around the edge case and since we're
 397                  * always a little behind anyways it shouldn't make a big
 398                  * difference.  If DMA has been stopped prior calling this
 399                  * then the position is always exact.
 400                  */
 401                 using_bufa = ((!(status & DCSR_BIU) &&  (status & DCSR_STRTA)) ||
 402                               ( (status & DCSR_BIU) && !(status & DCSR_STRTB)));
 403                 if (buf_id)
 404                         *buf_id = buf->id;
 405                 *addr = (using_bufa) ? regs->DBSA : regs->DBSB;
 406                 /*
 407                  * Clamp funky pointers sometimes returned by the hardware
 408                  * on completed DMA transfers
 409                  */
 410                 if (*addr < buf->dma_start ||
 411                     *addr > buf->dma_ptr)
 412                         *addr = buf->dma_ptr;
 413                 DPRINTK("curr_pos: b=%#x a=%#x\n", (int)dma->curr->id, *addr);
 414                 ret = 0;
 415         } else if (dma->tail && dma->stopped) {
 416                 dma_buf_t *buf = dma->tail;
 417                 if (buf_id)
 418                         *buf_id = buf->id;
 419                 *addr = buf->dma_ptr;
 420                 ret = 0;
 421         } else {
 422                 if (buf_id)
 423                         *buf_id = NULL;
 424                 *addr = 0;
 425                 ret = -ENXIO;
 426         }
 427         local_irq_restore(flags);
 428         return ret;
 429 }
 430
 431
 432 int sa1100_dma_stop(dmach_t channel)
 433 {
 434         sa1100_dma_t *dma = &dma_chan[channel];
 435         int flags;
 436
 437         if (channel_is_sa1111_sac(channel))
 438                 return sa1111_dma_stop(channel);
 439
 440         if (dma->stopped)
 441                 return 0;
 442         local_irq_save(flags);
 443         dma->stopped = 1;
 444         /*
 445          * Stop DMA and tweak state variables so everything could restart
 446          * from there when resume/wakeup occurs.
 447          */
 448         dma->regs->ClrDCSR = DCSR_RUN | DCSR_IE;
 449         if (dma->curr) {
 450                 dma_buf_t *buf = dma->curr;
 451                 if (dma->spin_ref <= 0) {
 452                         dma_addr_t curpos;
 453                         sa1100_dma_get_current(channel, NULL, &curpos);
 454                         buf->size += buf->dma_ptr - curpos;
 455                         buf->dma_ptr = curpos;
 456                 }
 457                 buf->ref = 0;
 458                 dma->tail = buf;
 459                 dma->curr = NULL;
 460         }
 461         dma->spin_ref = 0;
 462         dma->regs->ClrDCSR = DCSR_STRTA|DCSR_STRTB|DCSR_DONEA|DCSR_DONEB;
 463         process_dma(dma);
 464         local_irq_restore(flags);
 465         return 0;
 466 }
 467
 468
 469 int sa1100_dma_resume(dmach_t channel)
 470 {
 471         sa1100_dma_t *dma = &dma_chan[channel];
 472
 473         if ((unsigned)channel >= MAX_SA1100_DMA_CHANNELS || !dma->in_use)
 474                 return -EINVAL;
 475
 476         if (channel_is_sa1111_sac(channel))
 477                 return sa1111_dma_resume(channel);
 478
 479         if (dma->stopped) {
 480                 unsigned long flags;
 481                 local_irq_save(flags);
 482                 dma->stopped = 0;
 483                 process_dma(dma);
 484                 local_irq_restore(flags);
 485         }
 486         return 0;
 487 }
 488
 489
 490 int sa1100_dma_flush_all(dmach_t channel)
 491 {
 492         sa1100_dma_t *dma = &dma_chan[channel];
 493         dma_buf_t *buf, *next_buf;
 494         int flags;
 495
 496         if ((unsigned)channel >= MAX_SA1100_DMA_CHANNELS || !dma->in_use)
 497                 return -EINVAL;
 498
 499         local_irq_save(flags);
 500         if (channel_is_sa1111_sac(channel))
 501                 sa1111_reset_sac_dma(channel);
 502         else
 503                 dma->regs->ClrDCSR = DCSR_STRTA|DCSR_STRTB|DCSR_DONEA|DCSR_DONEB|DCSR_RUN|DCSR_IE;
 504         buf = dma->curr;
 505         if (!buf)
 506                 buf = dma->tail;
 507         dma->head = dma->tail = dma->curr = NULL;
 508         dma->stopped = 0;
 509         dma->spin_ref = 0;
 510         process_dma(dma);
 511         local_irq_restore(flags);
 512         while (buf) {
 513                 next_buf = buf->next;
 514                 kfree(buf);
 515                 buf = next_buf;
 516         }
 517         DPRINTK("flushed\n");
 518         return 0;
 519 }
 520
 521
 522 void sa1100_free_dma(dmach_t channel)
 523 {
 524         sa1100_dma_t *dma;
 525
 526         if ((unsigned)channel >= MAX_SA1100_DMA_CHANNELS)
 527                 return;
 528
 529         dma = &dma_chan[channel];
 530         if (!dma->in_use) {
 531                 printk(KERN_ERR "Trying to free free DMA%d\n", channel);
 532                 return;
 533         }
 534
 535         sa1100_dma_set_spin(channel, 0, 0);
 536         sa1100_dma_flush_all(channel);
 537
 538         if (channel_is_sa1111_sac(channel)) {
 539                 sa1111_cleanup_sac_dma(channel);
 540         } else {
 541                 free_irq(IRQ_DMA0 + channel, (void *) dma);
 542         }
 543         dma->in_use = 0;
 544
 545         DPRINTK("freed\n");
 546 }
 547
 548
 549 EXPORT_SYMBOL(sa1100_request_dma);
 550 EXPORT_SYMBOL(sa1100_dma_set_callback);
 551 EXPORT_SYMBOL(sa1100_dma_set_spin);
 552 EXPORT_SYMBOL(sa1100_dma_queue_buffer);
 553 EXPORT_SYMBOL(sa1100_dma_get_current);
 554 EXPORT_SYMBOL(sa1100_dma_stop);
 555 EXPORT_SYMBOL(sa1100_dma_resume);
 556 EXPORT_SYMBOL(sa1100_dma_flush_all);
 557 EXPORT_SYMBOL(sa1100_free_dma);
 558
 559
 560 #ifdef CONFIG_PM
 561 /* Drivers should call this from their PM callback function */
 562
 563 int sa1100_dma_sleep(dmach_t channel)
 564 {
 565         sa1100_dma_t *dma = &dma_chan[channel];
 566         int orig_state;
 567
 568         if ((unsigned)channel >= MAX_SA1100_DMA_CHANNELS || !dma->in_use)
 569                 return -EINVAL;
 570
 571         if (channel_is_sa1111_sac(channel)) {
 572                 /* We'll cheat a little until someone actually
 573                  * write the real thing.
 574                  */
 575                 sa1111_reset_sac_dma(channel);
 576                 return 0;
 577         }
 578
 579         orig_state = dma->stopped;
 580         sa1100_dma_stop(channel);
 581         dma->regs->ClrDCSR = DCSR_RUN | DCSR_IE | DCSR_STRTA | DCSR_STRTB;
 582         dma->stopped = orig_state;
 583         dma->spin_ref = 0;
 584         return 0;
 585 }
 586
 587 int sa1100_dma_wakeup(dmach_t channel)
 588 {
 589         sa1100_dma_t *dma = &dma_chan[channel];
 590         dma_regs_t *regs;
 591         int flags;
 592
 593         if ((unsigned)channel >= MAX_SA1100_DMA_CHANNELS || !dma->in_use)
 594                 return -EINVAL;
 595
 596         if (channel_is_sa1111_sac(channel)) {
 597                 /* We'll cheat a little until someone actually
 598                  * write the real thing.
 599                  */
 600                 return 0;
 601         }
 602
 603         regs = dma->regs;
 604         regs->ClrDCSR =
 605                 (DCSR_DONEA | DCSR_DONEB | DCSR_STRTA | DCSR_STRTB |
 606                  DCSR_IE | DCSR_ERROR | DCSR_RUN);
 607         regs->DDAR = dma->device;
 608         local_irq_save(flags);
 609         process_dma(dma);
 610         local_irq_restore(flags);
 611         return 0;
 612 }
 613
 614 EXPORT_SYMBOL(sa1100_dma_sleep);
 615 EXPORT_SYMBOL(sa1100_dma_wakeup);
 616
 617 #endif
 618
 619
 620 static int __init sa1100_init_dma(void)
 621 {
 622         int channel;
 623         for (channel = 0; channel < SA1100_DMA_CHANNELS; channel++) {
 624                 dma_chan[channel].regs =
 625                     (dma_regs_t *) &DDAR(channel);
 626                 dma_chan[channel].irq = IRQ_DMA0 + channel;
 627         }
 628         return 0;
 629 }
 630
 631 __initcall(sa1100_init_dma);