linux/drivers/staging/comedi/drivers/mite.c
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   1/*
   2 * comedi/drivers/mite.c
   3 * Hardware driver for NI Mite PCI interface chip
   4 *
   5 * COMEDI - Linux Control and Measurement Device Interface
   6 * Copyright (C) 1997-2002 David A. Schleef <ds@schleef.org>
   7 *
   8 * This program is free software; you can redistribute it and/or modify
   9 * it under the terms of the GNU General Public License as published by
  10 * the Free Software Foundation; either version 2 of the License, or
  11 * (at your option) any later version.
  12 *
  13 * This program is distributed in the hope that it will be useful,
  14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16 * GNU General Public License for more details.
  17 */
  18
  19/*
  20 * The PCI-MIO E series driver was originally written by
  21 * Tomasz Motylewski <...>, and ported to comedi by ds.
  22 *
  23 * References for specifications:
  24 *
  25 *    321747b.pdf  Register Level Programmer Manual (obsolete)
  26 *    321747c.pdf  Register Level Programmer Manual (new)
  27 *    DAQ-STC reference manual
  28 *
  29 * Other possibly relevant info:
  30 *
  31 *    320517c.pdf  User manual (obsolete)
  32 *    320517f.pdf  User manual (new)
  33 *    320889a.pdf  delete
  34 *    320906c.pdf  maximum signal ratings
  35 *    321066a.pdf  about 16x
  36 *    321791a.pdf  discontinuation of at-mio-16e-10 rev. c
  37 *    321808a.pdf  about at-mio-16e-10 rev P
  38 *    321837a.pdf  discontinuation of at-mio-16de-10 rev d
  39 *    321838a.pdf  about at-mio-16de-10 rev N
  40 *
  41 * ISSUES:
  42 *
  43 */
  44
  45#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  46
  47#include <linux/module.h>
  48#include <linux/slab.h>
  49
  50#include "../comedi_pci.h"
  51
  52#include "mite.h"
  53
  54#define TOP_OF_PAGE(x) ((x)|(~(PAGE_MASK)))
  55
  56struct mite_struct *mite_alloc(struct pci_dev *pcidev)
  57{
  58        struct mite_struct *mite;
  59        unsigned int i;
  60
  61        mite = kzalloc(sizeof(*mite), GFP_KERNEL);
  62        if (mite) {
  63                spin_lock_init(&mite->lock);
  64                mite->pcidev = pcidev;
  65                for (i = 0; i < MAX_MITE_DMA_CHANNELS; ++i) {
  66                        mite->channels[i].mite = mite;
  67                        mite->channels[i].channel = i;
  68                        mite->channels[i].done = 1;
  69                }
  70        }
  71        return mite;
  72}
  73EXPORT_SYMBOL_GPL(mite_alloc);
  74
  75static void dump_chip_signature(u32 csigr_bits)
  76{
  77        pr_info("version = %i, type = %i, mite mode = %i, interface mode = %i\n",
  78                mite_csigr_version(csigr_bits), mite_csigr_type(csigr_bits),
  79                mite_csigr_mmode(csigr_bits), mite_csigr_imode(csigr_bits));
  80        pr_info("num channels = %i, write post fifo depth = %i, wins = %i, iowins = %i\n",
  81                mite_csigr_dmac(csigr_bits), mite_csigr_wpdep(csigr_bits),
  82                mite_csigr_wins(csigr_bits), mite_csigr_iowins(csigr_bits));
  83}
  84
  85static unsigned mite_fifo_size(struct mite_struct *mite, unsigned channel)
  86{
  87        unsigned fcr_bits = readl(mite->mite_io_addr + MITE_FCR(channel));
  88        unsigned empty_count = (fcr_bits >> 16) & 0xff;
  89        unsigned full_count = fcr_bits & 0xff;
  90
  91        return empty_count + full_count;
  92}
  93
  94int mite_setup2(struct comedi_device *dev,
  95                struct mite_struct *mite, bool use_win1)
  96{
  97        unsigned long length;
  98        int i;
  99        u32 csigr_bits;
 100        unsigned unknown_dma_burst_bits;
 101
 102        pci_set_master(mite->pcidev);
 103
 104        mite->mite_io_addr = pci_ioremap_bar(mite->pcidev, 0);
 105        if (!mite->mite_io_addr) {
 106                dev_err(dev->class_dev,
 107                        "Failed to remap mite io memory address\n");
 108                return -ENOMEM;
 109        }
 110        mite->mite_phys_addr = pci_resource_start(mite->pcidev, 0);
 111
 112        dev->mmio = pci_ioremap_bar(mite->pcidev, 1);
 113        if (!dev->mmio) {
 114                dev_err(dev->class_dev,
 115                        "Failed to remap daq io memory address\n");
 116                return -ENOMEM;
 117        }
 118        mite->daq_phys_addr = pci_resource_start(mite->pcidev, 1);
 119        length = pci_resource_len(mite->pcidev, 1);
 120
 121        if (use_win1) {
 122                writel(0, mite->mite_io_addr + MITE_IODWBSR);
 123                dev_info(dev->class_dev,
 124                         "using I/O Window Base Size register 1\n");
 125                writel(mite->daq_phys_addr | WENAB |
 126                       MITE_IODWBSR_1_WSIZE_bits(length),
 127                       mite->mite_io_addr + MITE_IODWBSR_1);
 128                writel(0, mite->mite_io_addr + MITE_IODWCR_1);
 129        } else {
 130                writel(mite->daq_phys_addr | WENAB,
 131                       mite->mite_io_addr + MITE_IODWBSR);
 132        }
 133        /*
 134         * Make sure dma bursts work. I got this from running a bus analyzer
 135         * on a pxi-6281 and a pxi-6713. 6713 powered up with register value
 136         * of 0x61f and bursts worked. 6281 powered up with register value of
 137         * 0x1f and bursts didn't work. The NI windows driver reads the
 138         * register, then does a bitwise-or of 0x600 with it and writes it back.
 139         */
 140        unknown_dma_burst_bits =
 141            readl(mite->mite_io_addr + MITE_UNKNOWN_DMA_BURST_REG);
 142        unknown_dma_burst_bits |= UNKNOWN_DMA_BURST_ENABLE_BITS;
 143        writel(unknown_dma_burst_bits,
 144               mite->mite_io_addr + MITE_UNKNOWN_DMA_BURST_REG);
 145
 146        csigr_bits = readl(mite->mite_io_addr + MITE_CSIGR);
 147        mite->num_channels = mite_csigr_dmac(csigr_bits);
 148        if (mite->num_channels > MAX_MITE_DMA_CHANNELS) {
 149                dev_warn(dev->class_dev,
 150                         "mite: bug? chip claims to have %i dma channels. Setting to %i.\n",
 151                         mite->num_channels, MAX_MITE_DMA_CHANNELS);
 152                mite->num_channels = MAX_MITE_DMA_CHANNELS;
 153        }
 154        dump_chip_signature(csigr_bits);
 155        for (i = 0; i < mite->num_channels; i++) {
 156                writel(CHOR_DMARESET, mite->mite_io_addr + MITE_CHOR(i));
 157                /* disable interrupts */
 158                writel(CHCR_CLR_DMA_IE | CHCR_CLR_LINKP_IE | CHCR_CLR_SAR_IE |
 159                       CHCR_CLR_DONE_IE | CHCR_CLR_MRDY_IE | CHCR_CLR_DRDY_IE |
 160                       CHCR_CLR_LC_IE | CHCR_CLR_CONT_RB_IE,
 161                       mite->mite_io_addr + MITE_CHCR(i));
 162        }
 163        mite->fifo_size = mite_fifo_size(mite, 0);
 164        dev_info(dev->class_dev, "fifo size is %i.\n", mite->fifo_size);
 165        return 0;
 166}
 167EXPORT_SYMBOL_GPL(mite_setup2);
 168
 169void mite_detach(struct mite_struct *mite)
 170{
 171        if (!mite)
 172                return;
 173
 174        if (mite->mite_io_addr)
 175                iounmap(mite->mite_io_addr);
 176
 177        kfree(mite);
 178}
 179EXPORT_SYMBOL_GPL(mite_detach);
 180
 181struct mite_dma_descriptor_ring *mite_alloc_ring(struct mite_struct *mite)
 182{
 183        struct mite_dma_descriptor_ring *ring =
 184            kmalloc(sizeof(struct mite_dma_descriptor_ring), GFP_KERNEL);
 185
 186        if (!ring)
 187                return NULL;
 188        ring->hw_dev = get_device(&mite->pcidev->dev);
 189        if (!ring->hw_dev) {
 190                kfree(ring);
 191                return NULL;
 192        }
 193        ring->n_links = 0;
 194        ring->descriptors = NULL;
 195        ring->descriptors_dma_addr = 0;
 196        return ring;
 197};
 198EXPORT_SYMBOL_GPL(mite_alloc_ring);
 199
 200void mite_free_ring(struct mite_dma_descriptor_ring *ring)
 201{
 202        if (ring) {
 203                if (ring->descriptors) {
 204                        dma_free_coherent(ring->hw_dev,
 205                                          ring->n_links *
 206                                          sizeof(struct mite_dma_descriptor),
 207                                          ring->descriptors,
 208                                          ring->descriptors_dma_addr);
 209                }
 210                put_device(ring->hw_dev);
 211                kfree(ring);
 212        }
 213};
 214EXPORT_SYMBOL_GPL(mite_free_ring);
 215
 216struct mite_channel *mite_request_channel_in_range(struct mite_struct *mite,
 217                                                   struct
 218                                                   mite_dma_descriptor_ring
 219                                                   *ring, unsigned min_channel,
 220                                                   unsigned max_channel)
 221{
 222        int i;
 223        unsigned long flags;
 224        struct mite_channel *channel = NULL;
 225
 226        /*
 227         * spin lock so mite_release_channel can be called safely
 228         * from interrupts
 229         */
 230        spin_lock_irqsave(&mite->lock, flags);
 231        for (i = min_channel; i <= max_channel; ++i) {
 232                if (mite->channel_allocated[i] == 0) {
 233                        mite->channel_allocated[i] = 1;
 234                        channel = &mite->channels[i];
 235                        channel->ring = ring;
 236                        break;
 237                }
 238        }
 239        spin_unlock_irqrestore(&mite->lock, flags);
 240        return channel;
 241}
 242EXPORT_SYMBOL_GPL(mite_request_channel_in_range);
 243
 244void mite_release_channel(struct mite_channel *mite_chan)
 245{
 246        struct mite_struct *mite = mite_chan->mite;
 247        unsigned long flags;
 248
 249        /* spin lock to prevent races with mite_request_channel */
 250        spin_lock_irqsave(&mite->lock, flags);
 251        if (mite->channel_allocated[mite_chan->channel]) {
 252                mite_dma_disarm(mite_chan);
 253                mite_dma_reset(mite_chan);
 254                /*
 255                 * disable all channel's interrupts (do it after disarm/reset so
 256                 * MITE_CHCR reg isn't changed while dma is still active!)
 257                 */
 258                writel(CHCR_CLR_DMA_IE | CHCR_CLR_LINKP_IE |
 259                       CHCR_CLR_SAR_IE | CHCR_CLR_DONE_IE |
 260                       CHCR_CLR_MRDY_IE | CHCR_CLR_DRDY_IE |
 261                       CHCR_CLR_LC_IE | CHCR_CLR_CONT_RB_IE,
 262                       mite->mite_io_addr + MITE_CHCR(mite_chan->channel));
 263                mite->channel_allocated[mite_chan->channel] = 0;
 264                mite_chan->ring = NULL;
 265                mmiowb();
 266        }
 267        spin_unlock_irqrestore(&mite->lock, flags);
 268}
 269EXPORT_SYMBOL_GPL(mite_release_channel);
 270
 271void mite_dma_arm(struct mite_channel *mite_chan)
 272{
 273        struct mite_struct *mite = mite_chan->mite;
 274        int chor;
 275        unsigned long flags;
 276
 277        /*
 278         * memory barrier is intended to insure any twiddling with the buffer
 279         * is done before writing to the mite to arm dma transfer
 280         */
 281        smp_mb();
 282        /* arm */
 283        chor = CHOR_START;
 284        spin_lock_irqsave(&mite->lock, flags);
 285        mite_chan->done = 0;
 286        writel(chor, mite->mite_io_addr + MITE_CHOR(mite_chan->channel));
 287        mmiowb();
 288        spin_unlock_irqrestore(&mite->lock, flags);
 289        /* mite_dma_tcr(mite, channel); */
 290}
 291EXPORT_SYMBOL_GPL(mite_dma_arm);
 292
 293/**************************************/
 294
 295int mite_buf_change(struct mite_dma_descriptor_ring *ring,
 296                    struct comedi_subdevice *s)
 297{
 298        struct comedi_async *async = s->async;
 299        unsigned int n_links;
 300
 301        if (ring->descriptors) {
 302                dma_free_coherent(ring->hw_dev,
 303                                  ring->n_links *
 304                                  sizeof(struct mite_dma_descriptor),
 305                                  ring->descriptors,
 306                                  ring->descriptors_dma_addr);
 307        }
 308        ring->descriptors = NULL;
 309        ring->descriptors_dma_addr = 0;
 310        ring->n_links = 0;
 311
 312        if (async->prealloc_bufsz == 0)
 313                return 0;
 314
 315        n_links = async->prealloc_bufsz >> PAGE_SHIFT;
 316
 317        ring->descriptors =
 318            dma_alloc_coherent(ring->hw_dev,
 319                               n_links * sizeof(struct mite_dma_descriptor),
 320                               &ring->descriptors_dma_addr, GFP_KERNEL);
 321        if (!ring->descriptors) {
 322                dev_err(s->device->class_dev,
 323                        "mite: ring buffer allocation failed\n");
 324                return -ENOMEM;
 325        }
 326        ring->n_links = n_links;
 327
 328        return mite_init_ring_descriptors(ring, s, n_links << PAGE_SHIFT);
 329}
 330EXPORT_SYMBOL_GPL(mite_buf_change);
 331
 332/*
 333 * initializes the ring buffer descriptors to provide correct DMA transfer links
 334 * to the exact amount of memory required.  When the ring buffer is allocated in
 335 * mite_buf_change, the default is to initialize the ring to refer to the entire
 336 * DMA data buffer.  A command may call this function later to re-initialize and
 337 * shorten the amount of memory that will be transferred.
 338 */
 339int mite_init_ring_descriptors(struct mite_dma_descriptor_ring *ring,
 340                               struct comedi_subdevice *s,
 341                               unsigned int nbytes)
 342{
 343        struct comedi_async *async = s->async;
 344        unsigned int n_full_links = nbytes >> PAGE_SHIFT;
 345        unsigned int remainder = nbytes % PAGE_SIZE;
 346        int i;
 347
 348        dev_dbg(s->device->class_dev,
 349                "mite: init ring buffer to %u bytes\n", nbytes);
 350
 351        if ((n_full_links + (remainder > 0 ? 1 : 0)) > ring->n_links) {
 352                dev_err(s->device->class_dev,
 353                        "mite: ring buffer too small for requested init\n");
 354                return -ENOMEM;
 355        }
 356
 357        /* We set the descriptors for all full links. */
 358        for (i = 0; i < n_full_links; ++i) {
 359                ring->descriptors[i].count = cpu_to_le32(PAGE_SIZE);
 360                ring->descriptors[i].addr =
 361                    cpu_to_le32(async->buf_map->page_list[i].dma_addr);
 362                ring->descriptors[i].next =
 363                    cpu_to_le32(ring->descriptors_dma_addr +
 364                                (i + 1) * sizeof(struct mite_dma_descriptor));
 365        }
 366
 367        /* the last link is either a remainder or was a full link. */
 368        if (remainder > 0) {
 369                /* set the lesser count for the remainder link */
 370                ring->descriptors[i].count = cpu_to_le32(remainder);
 371                ring->descriptors[i].addr =
 372                    cpu_to_le32(async->buf_map->page_list[i].dma_addr);
 373                /* increment i so that assignment below refs last link */
 374                ++i;
 375        }
 376
 377        /* Assign the last link->next to point back to the head of the list. */
 378        ring->descriptors[i - 1].next = cpu_to_le32(ring->descriptors_dma_addr);
 379
 380        /*
 381         * barrier is meant to insure that all the writes to the dma descriptors
 382         * have completed before the dma controller is commanded to read them
 383         */
 384        smp_wmb();
 385        return 0;
 386}
 387EXPORT_SYMBOL_GPL(mite_init_ring_descriptors);
 388
 389void mite_prep_dma(struct mite_channel *mite_chan,
 390                   unsigned int num_device_bits, unsigned int num_memory_bits)
 391{
 392        unsigned int chor, chcr, mcr, dcr, lkcr;
 393        struct mite_struct *mite = mite_chan->mite;
 394
 395        /* reset DMA and FIFO */
 396        chor = CHOR_DMARESET | CHOR_FRESET;
 397        writel(chor, mite->mite_io_addr + MITE_CHOR(mite_chan->channel));
 398
 399        /* short link chaining mode */
 400        chcr = CHCR_SET_DMA_IE | CHCR_LINKSHORT | CHCR_SET_DONE_IE |
 401            CHCR_BURSTEN;
 402        /*
 403         * Link Complete Interrupt: interrupt every time a link
 404         * in MITE_RING is completed. This can generate a lot of
 405         * extra interrupts, but right now we update the values
 406         * of buf_int_ptr and buf_int_count at each interrupt. A
 407         * better method is to poll the MITE before each user
 408         * "read()" to calculate the number of bytes available.
 409         */
 410        chcr |= CHCR_SET_LC_IE;
 411        if (num_memory_bits == 32 && num_device_bits == 16) {
 412                /*
 413                 * Doing a combined 32 and 16 bit byteswap gets the 16 bit
 414                 * samples into the fifo in the right order. Tested doing 32 bit
 415                 * memory to 16 bit device transfers to the analog out of a
 416                 * pxi-6281, which has mite version = 1, type = 4. This also
 417                 * works for dma reads from the counters on e-series boards.
 418                 */
 419                chcr |= CHCR_BYTE_SWAP_DEVICE | CHCR_BYTE_SWAP_MEMORY;
 420        }
 421        if (mite_chan->dir == COMEDI_INPUT)
 422                chcr |= CHCR_DEV_TO_MEM;
 423
 424        writel(chcr, mite->mite_io_addr + MITE_CHCR(mite_chan->channel));
 425
 426        /* to/from memory */
 427        mcr = CR_RL(64) | CR_ASEQUP;
 428        switch (num_memory_bits) {
 429        case 8:
 430                mcr |= CR_PSIZE8;
 431                break;
 432        case 16:
 433                mcr |= CR_PSIZE16;
 434                break;
 435        case 32:
 436                mcr |= CR_PSIZE32;
 437                break;
 438        default:
 439                pr_warn("bug! invalid mem bit width for dma transfer\n");
 440                break;
 441        }
 442        writel(mcr, mite->mite_io_addr + MITE_MCR(mite_chan->channel));
 443
 444        /* from/to device */
 445        dcr = CR_RL(64) | CR_ASEQUP;
 446        dcr |= CR_PORTIO | CR_AMDEVICE | CR_REQSDRQ(mite_chan->channel);
 447        switch (num_device_bits) {
 448        case 8:
 449                dcr |= CR_PSIZE8;
 450                break;
 451        case 16:
 452                dcr |= CR_PSIZE16;
 453                break;
 454        case 32:
 455                dcr |= CR_PSIZE32;
 456                break;
 457        default:
 458                pr_warn("bug! invalid dev bit width for dma transfer\n");
 459                break;
 460        }
 461        writel(dcr, mite->mite_io_addr + MITE_DCR(mite_chan->channel));
 462
 463        /* reset the DAR */
 464        writel(0, mite->mite_io_addr + MITE_DAR(mite_chan->channel));
 465
 466        /* the link is 32bits */
 467        lkcr = CR_RL(64) | CR_ASEQUP | CR_PSIZE32;
 468        writel(lkcr, mite->mite_io_addr + MITE_LKCR(mite_chan->channel));
 469
 470        /* starting address for link chaining */
 471        writel(mite_chan->ring->descriptors_dma_addr,
 472               mite->mite_io_addr + MITE_LKAR(mite_chan->channel));
 473}
 474EXPORT_SYMBOL_GPL(mite_prep_dma);
 475
 476static u32 mite_device_bytes_transferred(struct mite_channel *mite_chan)
 477{
 478        struct mite_struct *mite = mite_chan->mite;
 479
 480        return readl(mite->mite_io_addr + MITE_DAR(mite_chan->channel));
 481}
 482
 483u32 mite_bytes_in_transit(struct mite_channel *mite_chan)
 484{
 485        struct mite_struct *mite = mite_chan->mite;
 486
 487        return readl(mite->mite_io_addr +
 488                     MITE_FCR(mite_chan->channel)) & 0x000000FF;
 489}
 490EXPORT_SYMBOL_GPL(mite_bytes_in_transit);
 491
 492/* returns lower bound for number of bytes transferred from device to memory */
 493u32 mite_bytes_written_to_memory_lb(struct mite_channel *mite_chan)
 494{
 495        u32 device_byte_count;
 496
 497        device_byte_count = mite_device_bytes_transferred(mite_chan);
 498        return device_byte_count - mite_bytes_in_transit(mite_chan);
 499}
 500EXPORT_SYMBOL_GPL(mite_bytes_written_to_memory_lb);
 501
 502/* returns upper bound for number of bytes transferred from device to memory */
 503u32 mite_bytes_written_to_memory_ub(struct mite_channel *mite_chan)
 504{
 505        u32 in_transit_count;
 506
 507        in_transit_count = mite_bytes_in_transit(mite_chan);
 508        return mite_device_bytes_transferred(mite_chan) - in_transit_count;
 509}
 510EXPORT_SYMBOL_GPL(mite_bytes_written_to_memory_ub);
 511
 512/* returns lower bound for number of bytes read from memory to device */
 513u32 mite_bytes_read_from_memory_lb(struct mite_channel *mite_chan)
 514{
 515        u32 device_byte_count;
 516
 517        device_byte_count = mite_device_bytes_transferred(mite_chan);
 518        return device_byte_count + mite_bytes_in_transit(mite_chan);
 519}
 520EXPORT_SYMBOL_GPL(mite_bytes_read_from_memory_lb);
 521
 522/* returns upper bound for number of bytes read from memory to device */
 523u32 mite_bytes_read_from_memory_ub(struct mite_channel *mite_chan)
 524{
 525        u32 in_transit_count;
 526
 527        in_transit_count = mite_bytes_in_transit(mite_chan);
 528        return mite_device_bytes_transferred(mite_chan) + in_transit_count;
 529}
 530EXPORT_SYMBOL_GPL(mite_bytes_read_from_memory_ub);
 531
 532unsigned mite_dma_tcr(struct mite_channel *mite_chan)
 533{
 534        struct mite_struct *mite = mite_chan->mite;
 535
 536        return readl(mite->mite_io_addr + MITE_TCR(mite_chan->channel));
 537}
 538EXPORT_SYMBOL_GPL(mite_dma_tcr);
 539
 540void mite_dma_disarm(struct mite_channel *mite_chan)
 541{
 542        struct mite_struct *mite = mite_chan->mite;
 543        unsigned chor;
 544
 545        /* disarm */
 546        chor = CHOR_ABORT;
 547        writel(chor, mite->mite_io_addr + MITE_CHOR(mite_chan->channel));
 548}
 549EXPORT_SYMBOL_GPL(mite_dma_disarm);
 550
 551int mite_sync_input_dma(struct mite_channel *mite_chan,
 552                        struct comedi_subdevice *s)
 553{
 554        struct comedi_async *async = s->async;
 555        int count;
 556        unsigned int nbytes, old_alloc_count;
 557
 558        old_alloc_count = async->buf_write_alloc_count;
 559        /* write alloc as much as we can */
 560        comedi_buf_write_alloc(s, async->prealloc_bufsz);
 561
 562        nbytes = mite_bytes_written_to_memory_lb(mite_chan);
 563        if ((int)(mite_bytes_written_to_memory_ub(mite_chan) -
 564                  old_alloc_count) > 0) {
 565                dev_warn(s->device->class_dev,
 566                         "mite: DMA overwrite of free area\n");
 567                async->events |= COMEDI_CB_OVERFLOW;
 568                return -1;
 569        }
 570
 571        count = nbytes - async->buf_write_count;
 572        /*
 573         * it's possible count will be negative due to conservative value
 574         * returned by mite_bytes_written_to_memory_lb
 575         */
 576        if (count <= 0)
 577                return 0;
 578
 579        comedi_buf_write_free(s, count);
 580        comedi_inc_scan_progress(s, count);
 581        async->events |= COMEDI_CB_BLOCK;
 582        return 0;
 583}
 584EXPORT_SYMBOL_GPL(mite_sync_input_dma);
 585
 586int mite_sync_output_dma(struct mite_channel *mite_chan,
 587                         struct comedi_subdevice *s)
 588{
 589        struct comedi_async *async = s->async;
 590        struct comedi_cmd *cmd = &async->cmd;
 591        u32 stop_count = cmd->stop_arg * comedi_bytes_per_scan(s);
 592        unsigned int old_alloc_count = async->buf_read_alloc_count;
 593        u32 nbytes_ub, nbytes_lb;
 594        int count;
 595        bool finite_regen = (cmd->stop_src == TRIG_NONE && stop_count != 0);
 596
 597        /* read alloc as much as we can */
 598        comedi_buf_read_alloc(s, async->prealloc_bufsz);
 599        nbytes_lb = mite_bytes_read_from_memory_lb(mite_chan);
 600        if (cmd->stop_src == TRIG_COUNT && (int)(nbytes_lb - stop_count) > 0)
 601                nbytes_lb = stop_count;
 602        nbytes_ub = mite_bytes_read_from_memory_ub(mite_chan);
 603        if (cmd->stop_src == TRIG_COUNT && (int)(nbytes_ub - stop_count) > 0)
 604                nbytes_ub = stop_count;
 605
 606        if ((!finite_regen || stop_count > old_alloc_count) &&
 607            ((int)(nbytes_ub - old_alloc_count) > 0)) {
 608                dev_warn(s->device->class_dev, "mite: DMA underrun\n");
 609                async->events |= COMEDI_CB_OVERFLOW;
 610                return -1;
 611        }
 612
 613        if (finite_regen) {
 614                /*
 615                 * This is a special case where we continuously output a finite
 616                 * buffer.  In this case, we do not free any of the memory,
 617                 * hence we expect that old_alloc_count will reach a maximum of
 618                 * stop_count bytes.
 619                 */
 620                return 0;
 621        }
 622
 623        count = nbytes_lb - async->buf_read_count;
 624        if (count <= 0)
 625                return 0;
 626
 627        if (count) {
 628                comedi_buf_read_free(s, count);
 629                async->events |= COMEDI_CB_BLOCK;
 630        }
 631        return 0;
 632}
 633EXPORT_SYMBOL_GPL(mite_sync_output_dma);
 634
 635unsigned mite_get_status(struct mite_channel *mite_chan)
 636{
 637        struct mite_struct *mite = mite_chan->mite;
 638        unsigned status;
 639        unsigned long flags;
 640
 641        spin_lock_irqsave(&mite->lock, flags);
 642        status = readl(mite->mite_io_addr + MITE_CHSR(mite_chan->channel));
 643        if (status & CHSR_DONE) {
 644                mite_chan->done = 1;
 645                writel(CHOR_CLRDONE,
 646                       mite->mite_io_addr + MITE_CHOR(mite_chan->channel));
 647        }
 648        mmiowb();
 649        spin_unlock_irqrestore(&mite->lock, flags);
 650        return status;
 651}
 652EXPORT_SYMBOL_GPL(mite_get_status);
 653
 654int mite_done(struct mite_channel *mite_chan)
 655{
 656        struct mite_struct *mite = mite_chan->mite;
 657        unsigned long flags;
 658        int done;
 659
 660        mite_get_status(mite_chan);
 661        spin_lock_irqsave(&mite->lock, flags);
 662        done = mite_chan->done;
 663        spin_unlock_irqrestore(&mite->lock, flags);
 664        return done;
 665}
 666EXPORT_SYMBOL_GPL(mite_done);
 667
 668static int __init mite_module_init(void)
 669{
 670        return 0;
 671}
 672
 673static void __exit mite_module_exit(void)
 674{
 675}
 676
 677module_init(mite_module_init);
 678module_exit(mite_module_exit);
 679
 680MODULE_AUTHOR("Comedi http://www.comedi.org");
 681MODULE_DESCRIPTION("Comedi helper for NI Mite PCI interface chip");
 682MODULE_LICENSE("GPL");
 683