git.oblomov.eu Git - linux-2.6/blob - drivers/spi/atmel_spi.c

   1 /*
   2  * Driver for Atmel AT32 and AT91 SPI Controllers
   3  *
   4  * Copyright (C) 2006 Atmel Corporation
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 as
   8  * published by the Free Software Foundation.
   9  */
  10
  11 #include <linux/kernel.h>
  12 #include <linux/init.h>
  13 #include <linux/clk.h>
  14 #include <linux/module.h>
  15 #include <linux/platform_device.h>
  16 #include <linux/delay.h>
  17 #include <linux/dma-mapping.h>
  18 #include <linux/err.h>
  19 #include <linux/interrupt.h>
  20 #include <linux/spi/spi.h>
  21
  22 #include <asm/io.h>
  23 #include <mach/board.h>
  24 #include <mach/gpio.h>
  25 #include <mach/cpu.h>
  26
  27 #include "atmel_spi.h"
  28
  29 /*
  30  * The core SPI transfer engine just talks to a register bank to set up
  31  * DMA transfers; transfer queue progress is driven by IRQs.  The clock
  32  * framework provides the base clock, subdivided for each spi_device.
  33  */
  34 struct atmel_spi {
  35         spinlock_t              lock;
  36
  37         void __iomem            *regs;
  38         int                     irq;
  39         struct clk              *clk;
  40         struct platform_device  *pdev;
  41         struct spi_device       *stay;
  42
  43         u8                      stopping;
  44         struct list_head        queue;
  45         struct spi_transfer     *current_transfer;
  46         unsigned long           current_remaining_bytes;
  47         struct spi_transfer     *next_transfer;
  48         unsigned long           next_remaining_bytes;
  49
  50         void                    *buffer;
  51         dma_addr_t              buffer_dma;
  52 };
  53
  54 /* Controller-specific per-slave state */
  55 struct atmel_spi_device {
  56         unsigned int            npcs_pin;
  57         u32                     csr;
  58 };
  59
  60 #define BUFFER_SIZE             PAGE_SIZE
  61 #define INVALID_DMA_ADDRESS     0xffffffff
  62
  63 /*
  64  * Version 2 of the SPI controller has
  65  *  - CR.LASTXFER
  66  *  - SPI_MR.DIV32 may become FDIV or must-be-zero (here: always zero)
  67  *  - SPI_SR.TXEMPTY, SPI_SR.NSSR (and corresponding irqs)
  68  *  - SPI_CSRx.CSAAT
  69  *  - SPI_CSRx.SBCR allows faster clocking
  70  *
  71  * We can determine the controller version by reading the VERSION
  72  * register, but I haven't checked that it exists on all chips, and
  73  * this is cheaper anyway.
  74  */
  75 static bool atmel_spi_is_v2(void)
  76 {
  77         return !cpu_is_at91rm9200();
  78 }
  79
  80 /*
  81  * Earlier SPI controllers (e.g. on at91rm9200) have a design bug whereby
  82  * they assume that spi slave device state will not change on deselect, so
  83  * that automagic deselection is OK.  ("NPCSx rises if no data is to be
  84  * transmitted")  Not so!  Workaround uses nCSx pins as GPIOs; or newer
  85  * controllers have CSAAT and friends.
  86  *
  87  * Since the CSAAT functionality is a bit weird on newer controllers as
  88  * well, we use GPIO to control nCSx pins on all controllers, updating
  89  * MR.PCS to avoid confusing the controller.  Using GPIOs also lets us
  90  * support active-high chipselects despite the controller's belief that
  91  * only active-low devices/systems exists.
  92  *
  93  * However, at91rm9200 has a second erratum whereby nCS0 doesn't work
  94  * right when driven with GPIO.  ("Mode Fault does not allow more than one
  95  * Master on Chip Select 0.")  No workaround exists for that ... so for
  96  * nCS0 on that chip, we (a) don't use the GPIO, (b) can't support CS_HIGH,
  97  * and (c) will trigger that first erratum in some cases.
  98  *
  99  * TODO: Test if the atmel_spi_is_v2() branch below works on
 100  * AT91RM9200 if we use some other register than CSR0. However, don't
 101  * do this unconditionally since AP7000 has an errata where the BITS
 102  * field in CSR0 overrides all other CSRs.
 103  */
 104
 105 static void cs_activate(struct atmel_spi *as, struct spi_device *spi)
 106 {
 107         struct atmel_spi_device *asd = spi->controller_state;
 108         unsigned active = spi->mode & SPI_CS_HIGH;
 109         u32 mr;
 110
 111         if (atmel_spi_is_v2()) {
 112                 /*
 113                  * Always use CSR0. This ensures that the clock
 114                  * switches to the correct idle polarity before we
 115                  * toggle the CS.
 116                  */
 117                 spi_writel(as, CSR0, asd->csr);
 118                 spi_writel(as, MR, SPI_BF(PCS, 0x0e) | SPI_BIT(MODFDIS)
 119                                 | SPI_BIT(MSTR));
 120                 mr = spi_readl(as, MR);
 121                 gpio_set_value(asd->npcs_pin, active);
 122         } else {
 123                 u32 cpol = (spi->mode & SPI_CPOL) ? SPI_BIT(CPOL) : 0;
 124                 int i;
 125                 u32 csr;
 126
 127                 /* Make sure clock polarity is correct */
 128                 for (i = 0; i < spi->master->num_chipselect; i++) {
 129                         csr = spi_readl(as, CSR0 + 4 * i);
 130                         if ((csr ^ cpol) & SPI_BIT(CPOL))
 131                                 spi_writel(as, CSR0 + 4 * i,
 132                                                 csr ^ SPI_BIT(CPOL));
 133                 }
 134
 135                 mr = spi_readl(as, MR);
 136                 mr = SPI_BFINS(PCS, ~(1 << spi->chip_select), mr);
 137                 if (spi->chip_select != 0)
 138                         gpio_set_value(asd->npcs_pin, active);
 139                 spi_writel(as, MR, mr);
 140         }
 141
 142         dev_dbg(&spi->dev, "activate %u%s, mr %08x\n",
 143                         asd->npcs_pin, active ? " (high)" : "",
 144                         mr);
 145 }
 146
 147 static void cs_deactivate(struct atmel_spi *as, struct spi_device *spi)
 148 {
 149         struct atmel_spi_device *asd = spi->controller_state;
 150         unsigned active = spi->mode & SPI_CS_HIGH;
 151         u32 mr;
 152
 153         /* only deactivate *this* device; sometimes transfers to
 154          * another device may be active when this routine is called.
 155          */
 156         mr = spi_readl(as, MR);
 157         if (~SPI_BFEXT(PCS, mr) & (1 << spi->chip_select)) {
 158                 mr = SPI_BFINS(PCS, 0xf, mr);
 159                 spi_writel(as, MR, mr);
 160         }
 161
 162         dev_dbg(&spi->dev, "DEactivate %u%s, mr %08x\n",
 163                         asd->npcs_pin, active ? " (low)" : "",
 164                         mr);
 165
 166         if (atmel_spi_is_v2() || spi->chip_select != 0)
 167                 gpio_set_value(asd->npcs_pin, !active);
 168 }
 169
 170 static inline int atmel_spi_xfer_is_last(struct spi_message *msg,
 171                                         struct spi_transfer *xfer)
 172 {
 173         return msg->transfers.prev == &xfer->transfer_list;
 174 }
 175
 176 static inline int atmel_spi_xfer_can_be_chained(struct spi_transfer *xfer)
 177 {
 178         return xfer->delay_usecs == 0 && !xfer->cs_change;
 179 }
 180
 181 static void atmel_spi_next_xfer_data(struct spi_master *master,
 182                                 struct spi_transfer *xfer,
 183                                 dma_addr_t *tx_dma,
 184                                 dma_addr_t *rx_dma,
 185                                 u32 *plen)
 186 {
 187         struct atmel_spi        *as = spi_master_get_devdata(master);
 188         u32                     len = *plen;
 189
 190         /* use scratch buffer only when rx or tx data is unspecified */
 191         if (xfer->rx_buf)
 192                 *rx_dma = xfer->rx_dma + xfer->len - len;
 193         else {
 194                 *rx_dma = as->buffer_dma;
 195                 if (len > BUFFER_SIZE)
 196                         len = BUFFER_SIZE;
 197         }
 198         if (xfer->tx_buf)
 199                 *tx_dma = xfer->tx_dma + xfer->len - len;
 200         else {
 201                 *tx_dma = as->buffer_dma;
 202                 if (len > BUFFER_SIZE)
 203                         len = BUFFER_SIZE;
 204                 memset(as->buffer, 0, len);
 205                 dma_sync_single_for_device(&as->pdev->dev,
 206                                 as->buffer_dma, len, DMA_TO_DEVICE);
 207         }
 208
 209         *plen = len;
 210 }
 211
 212 /*
 213  * Submit next transfer for DMA.
 214  * lock is held, spi irq is blocked
 215  */
 216 static void atmel_spi_next_xfer(struct spi_master *master,
 217                                 struct spi_message *msg)
 218 {
 219         struct atmel_spi        *as = spi_master_get_devdata(master);
 220         struct spi_transfer     *xfer;
 221         u32                     len, remaining;
 222         u32                     ieval;
 223         dma_addr_t              tx_dma, rx_dma;
 224
 225         if (!as->current_transfer)
 226                 xfer = list_entry(msg->transfers.next,
 227                                 struct spi_transfer, transfer_list);
 228         else if (!as->next_transfer)
 229                 xfer = list_entry(as->current_transfer->transfer_list.next,
 230                                 struct spi_transfer, transfer_list);
 231         else
 232                 xfer = NULL;
 233
 234         if (xfer) {
 235                 spi_writel(as, PTCR, SPI_BIT(RXTDIS) | SPI_BIT(TXTDIS));
 236
 237                 len = xfer->len;
 238                 atmel_spi_next_xfer_data(master, xfer, &tx_dma, &rx_dma, &len);
 239                 remaining = xfer->len - len;
 240
 241                 spi_writel(as, RPR, rx_dma);
 242                 spi_writel(as, TPR, tx_dma);
 243
 244                 if (msg->spi->bits_per_word > 8)
 245                         len >>= 1;
 246                 spi_writel(as, RCR, len);
 247                 spi_writel(as, TCR, len);
 248
 249                 dev_dbg(&msg->spi->dev,
 250                         "  start xfer %p: len %u tx %p/%08x rx %p/%08x\n",
 251                         xfer, xfer->len, xfer->tx_buf, xfer->tx_dma,
 252                         xfer->rx_buf, xfer->rx_dma);
 253         } else {
 254                 xfer = as->next_transfer;
 255                 remaining = as->next_remaining_bytes;
 256         }
 257
 258         as->current_transfer = xfer;
 259         as->current_remaining_bytes = remaining;
 260
 261         if (remaining > 0)
 262                 len = remaining;
 263         else if (!atmel_spi_xfer_is_last(msg, xfer)
 264                         && atmel_spi_xfer_can_be_chained(xfer)) {
 265                 xfer = list_entry(xfer->transfer_list.next,
 266                                 struct spi_transfer, transfer_list);
 267                 len = xfer->len;
 268         } else
 269                 xfer = NULL;
 270
 271         as->next_transfer = xfer;
 272
 273         if (xfer) {
 274                 u32     total;
 275
 276                 total = len;
 277                 atmel_spi_next_xfer_data(master, xfer, &tx_dma, &rx_dma, &len);
 278                 as->next_remaining_bytes = total - len;
 279
 280                 spi_writel(as, RNPR, rx_dma);
 281                 spi_writel(as, TNPR, tx_dma);
 282
 283                 if (msg->spi->bits_per_word > 8)
 284                         len >>= 1;
 285                 spi_writel(as, RNCR, len);
 286                 spi_writel(as, TNCR, len);
 287
 288                 dev_dbg(&msg->spi->dev,
 289                         "  next xfer %p: len %u tx %p/%08x rx %p/%08x\n",
 290                         xfer, xfer->len, xfer->tx_buf, xfer->tx_dma,
 291                         xfer->rx_buf, xfer->rx_dma);
 292                 ieval = SPI_BIT(ENDRX) | SPI_BIT(OVRES);
 293         } else {
 294                 spi_writel(as, RNCR, 0);
 295                 spi_writel(as, TNCR, 0);
 296                 ieval = SPI_BIT(RXBUFF) | SPI_BIT(ENDRX) | SPI_BIT(OVRES);
 297         }
 298
 299         /* REVISIT: We're waiting for ENDRX before we start the next
 300          * transfer because we need to handle some difficult timing
 301          * issues otherwise. If we wait for ENDTX in one transfer and
 302          * then starts waiting for ENDRX in the next, it's difficult
 303          * to tell the difference between the ENDRX interrupt we're
 304          * actually waiting for and the ENDRX interrupt of the
 305          * previous transfer.
 306          *
 307          * It should be doable, though. Just not now...
 308          */
 309         spi_writel(as, IER, ieval);
 310         spi_writel(as, PTCR, SPI_BIT(TXTEN) | SPI_BIT(RXTEN));
 311 }
 312
 313 static void atmel_spi_next_message(struct spi_master *master)
 314 {
 315         struct atmel_spi        *as = spi_master_get_devdata(master);
 316         struct spi_message      *msg;
 317         struct spi_device       *spi;
 318
 319         BUG_ON(as->current_transfer);
 320
 321         msg = list_entry(as->queue.next, struct spi_message, queue);
 322         spi = msg->spi;
 323
 324         dev_dbg(master->dev.parent, "start message %p for %s\n",
 325                         msg, spi->dev.bus_id);
 326
 327         /* select chip if it's not still active */
 328         if (as->stay) {
 329                 if (as->stay != spi) {
 330                         cs_deactivate(as, as->stay);
 331                         cs_activate(as, spi);
 332                 }
 333                 as->stay = NULL;
 334         } else
 335                 cs_activate(as, spi);
 336
 337         atmel_spi_next_xfer(master, msg);
 338 }
 339
 340 /*
 341  * For DMA, tx_buf/tx_dma have the same relationship as rx_buf/rx_dma:
 342  *  - The buffer is either valid for CPU access, else NULL
 343  *  - If the buffer is valid, so is its DMA addresss
 344  *
 345  * This driver manages the dma addresss unless message->is_dma_mapped.
 346  */
 347 static int
 348 atmel_spi_dma_map_xfer(struct atmel_spi *as, struct spi_transfer *xfer)
 349 {
 350         struct device   *dev = &as->pdev->dev;
 351
 352         xfer->tx_dma = xfer->rx_dma = INVALID_DMA_ADDRESS;
 353         if (xfer->tx_buf) {
 354                 xfer->tx_dma = dma_map_single(dev,
 355                                 (void *) xfer->tx_buf, xfer->len,
 356                                 DMA_TO_DEVICE);
 357                 if (dma_mapping_error(dev, xfer->tx_dma))
 358                         return -ENOMEM;
 359         }
 360         if (xfer->rx_buf) {
 361                 xfer->rx_dma = dma_map_single(dev,
 362                                 xfer->rx_buf, xfer->len,
 363                                 DMA_FROM_DEVICE);
 364                 if (dma_mapping_error(dev, xfer->rx_dma)) {
 365                         if (xfer->tx_buf)
 366                                 dma_unmap_single(dev,
 367                                                 xfer->tx_dma, xfer->len,
 368                                                 DMA_TO_DEVICE);
 369                         return -ENOMEM;
 370                 }
 371         }
 372         return 0;
 373 }
 374
 375 static void atmel_spi_dma_unmap_xfer(struct spi_master *master,
 376                                      struct spi_transfer *xfer)
 377 {
 378         if (xfer->tx_dma != INVALID_DMA_ADDRESS)
 379                 dma_unmap_single(master->dev.parent, xfer->tx_dma,
 380                                  xfer->len, DMA_TO_DEVICE);
 381         if (xfer->rx_dma != INVALID_DMA_ADDRESS)
 382                 dma_unmap_single(master->dev.parent, xfer->rx_dma,
 383                                  xfer->len, DMA_FROM_DEVICE);
 384 }
 385
 386 static void
 387 atmel_spi_msg_done(struct spi_master *master, struct atmel_spi *as,
 388                 struct spi_message *msg, int status, int stay)
 389 {
 390         if (!stay || status < 0)
 391                 cs_deactivate(as, msg->spi);
 392         else
 393                 as->stay = msg->spi;
 394
 395         list_del(&msg->queue);
 396         msg->status = status;
 397
 398         dev_dbg(master->dev.parent,
 399                 "xfer complete: %u bytes transferred\n",
 400                 msg->actual_length);
 401
 402         spin_unlock(&as->lock);
 403         msg->complete(msg->context);
 404         spin_lock(&as->lock);
 405
 406         as->current_transfer = NULL;
 407         as->next_transfer = NULL;
 408
 409         /* continue if needed */
 410         if (list_empty(&as->queue) || as->stopping)
 411                 spi_writel(as, PTCR, SPI_BIT(RXTDIS) | SPI_BIT(TXTDIS));
 412         else
 413                 atmel_spi_next_message(master);
 414 }
 415
 416 static irqreturn_t
 417 atmel_spi_interrupt(int irq, void *dev_id)
 418 {
 419         struct spi_master       *master = dev_id;
 420         struct atmel_spi        *as = spi_master_get_devdata(master);
 421         struct spi_message      *msg;
 422         struct spi_transfer     *xfer;
 423         u32                     status, pending, imr;
 424         int                     ret = IRQ_NONE;
 425
 426         spin_lock(&as->lock);
 427
 428         xfer = as->current_transfer;
 429         msg = list_entry(as->queue.next, struct spi_message, queue);
 430
 431         imr = spi_readl(as, IMR);
 432         status = spi_readl(as, SR);
 433         pending = status & imr;
 434
 435         if (pending & SPI_BIT(OVRES)) {
 436                 int timeout;
 437
 438                 ret = IRQ_HANDLED;
 439
 440                 spi_writel(as, IDR, (SPI_BIT(RXBUFF) | SPI_BIT(ENDRX)
 441                                      | SPI_BIT(OVRES)));
 442
 443                 /*
 444                  * When we get an overrun, we disregard the current
 445                  * transfer. Data will not be copied back from any
 446                  * bounce buffer and msg->actual_len will not be
 447                  * updated with the last xfer.
 448                  *
 449                  * We will also not process any remaning transfers in
 450                  * the message.
 451                  *
 452                  * First, stop the transfer and unmap the DMA buffers.
 453                  */
 454                 spi_writel(as, PTCR, SPI_BIT(RXTDIS) | SPI_BIT(TXTDIS));
 455                 if (!msg->is_dma_mapped)
 456                         atmel_spi_dma_unmap_xfer(master, xfer);
 457
 458                 /* REVISIT: udelay in irq is unfriendly */
 459                 if (xfer->delay_usecs)
 460                         udelay(xfer->delay_usecs);
 461
 462                 dev_warn(master->dev.parent, "overrun (%u/%u remaining)\n",
 463                          spi_readl(as, TCR), spi_readl(as, RCR));
 464
 465                 /*
 466                  * Clean up DMA registers and make sure the data
 467                  * registers are empty.
 468                  */
 469                 spi_writel(as, RNCR, 0);
 470                 spi_writel(as, TNCR, 0);
 471                 spi_writel(as, RCR, 0);
 472                 spi_writel(as, TCR, 0);
 473                 for (timeout = 1000; timeout; timeout--)
 474                         if (spi_readl(as, SR) & SPI_BIT(TXEMPTY))
 475                                 break;
 476                 if (!timeout)
 477                         dev_warn(master->dev.parent,
 478                                  "timeout waiting for TXEMPTY");
 479                 while (spi_readl(as, SR) & SPI_BIT(RDRF))
 480                         spi_readl(as, RDR);
 481
 482                 /* Clear any overrun happening while cleaning up */
 483                 spi_readl(as, SR);
 484
 485                 atmel_spi_msg_done(master, as, msg, -EIO, 0);
 486         } else if (pending & (SPI_BIT(RXBUFF) | SPI_BIT(ENDRX))) {
 487                 ret = IRQ_HANDLED;
 488
 489                 spi_writel(as, IDR, pending);
 490
 491                 if (as->current_remaining_bytes == 0) {
 492                         msg->actual_length += xfer->len;
 493
 494                         if (!msg->is_dma_mapped)
 495                                 atmel_spi_dma_unmap_xfer(master, xfer);
 496
 497                         /* REVISIT: udelay in irq is unfriendly */
 498                         if (xfer->delay_usecs)
 499                                 udelay(xfer->delay_usecs);
 500
 501                         if (atmel_spi_xfer_is_last(msg, xfer)) {
 502                                 /* report completed message */
 503                                 atmel_spi_msg_done(master, as, msg, 0,
 504                                                 xfer->cs_change);
 505                         } else {
 506                                 if (xfer->cs_change) {
 507                                         cs_deactivate(as, msg->spi);
 508                                         udelay(1);
 509                                         cs_activate(as, msg->spi);
 510                                 }
 511
 512                                 /*
 513                                  * Not done yet. Submit the next transfer.
 514                                  *
 515                                  * FIXME handle protocol options for xfer
 516                                  */
 517                                 atmel_spi_next_xfer(master, msg);
 518                         }
 519                 } else {
 520                         /*
 521                          * Keep going, we still have data to send in
 522                          * the current transfer.
 523                          */
 524                         atmel_spi_next_xfer(master, msg);
 525                 }
 526         }
 527
 528         spin_unlock(&as->lock);
 529
 530         return ret;
 531 }
 532
 533 /* the spi->mode bits understood by this driver: */
 534 #define MODEBITS (SPI_CPOL | SPI_CPHA | SPI_CS_HIGH)
 535
 536 static int atmel_spi_setup(struct spi_device *spi)
 537 {
 538         struct atmel_spi        *as;
 539         struct atmel_spi_device *asd;
 540         u32                     scbr, csr;
 541         unsigned int            bits = spi->bits_per_word;
 542         unsigned long           bus_hz;
 543         unsigned int            npcs_pin;
 544         int                     ret;
 545
 546         as = spi_master_get_devdata(spi->master);
 547
 548         if (as->stopping)
 549                 return -ESHUTDOWN;
 550
 551         if (spi->chip_select > spi->master->num_chipselect) {
 552                 dev_dbg(&spi->dev,
 553                                 "setup: invalid chipselect %u (%u defined)\n",
 554                                 spi->chip_select, spi->master->num_chipselect);
 555                 return -EINVAL;
 556         }
 557
 558         if (bits == 0)
 559                 bits = 8;
 560         if (bits < 8 || bits > 16) {
 561                 dev_dbg(&spi->dev,
 562                                 "setup: invalid bits_per_word %u (8 to 16)\n",
 563                                 bits);
 564                 return -EINVAL;
 565         }
 566
 567         if (spi->mode & ~MODEBITS) {
 568                 dev_dbg(&spi->dev, "setup: unsupported mode bits %x\n",
 569                         spi->mode & ~MODEBITS);
 570                 return -EINVAL;
 571         }
 572
 573         /* see notes above re chipselect */
 574         if (!atmel_spi_is_v2()
 575                         && spi->chip_select == 0
 576                         && (spi->mode & SPI_CS_HIGH)) {
 577                 dev_dbg(&spi->dev, "setup: can't be active-high\n");
 578                 return -EINVAL;
 579         }
 580
 581         /* v1 chips start out at half the peripheral bus speed. */
 582         bus_hz = clk_get_rate(as->clk);
 583         if (!atmel_spi_is_v2())
 584                 bus_hz /= 2;
 585
 586         if (spi->max_speed_hz) {
 587                 /*
 588                  * Calculate the lowest divider that satisfies the
 589                  * constraint, assuming div32/fdiv/mbz == 0.
 590                  */
 591                 scbr = DIV_ROUND_UP(bus_hz, spi->max_speed_hz);
 592
 593                 /*
 594                  * If the resulting divider doesn't fit into the
 595                  * register bitfield, we can't satisfy the constraint.
 596                  */
 597                 if (scbr >= (1 << SPI_SCBR_SIZE)) {
 598                         dev_dbg(&spi->dev,
 599                                 "setup: %d Hz too slow, scbr %u; min %ld Hz\n",
 600                                 spi->max_speed_hz, scbr, bus_hz/255);
 601                         return -EINVAL;
 602                 }
 603         } else
 604                 /* speed zero means "as slow as possible" */
 605                 scbr = 0xff;
 606
 607         csr = SPI_BF(SCBR, scbr) | SPI_BF(BITS, bits - 8);
 608         if (spi->mode & SPI_CPOL)
 609                 csr |= SPI_BIT(CPOL);
 610         if (!(spi->mode & SPI_CPHA))
 611                 csr |= SPI_BIT(NCPHA);
 612
 613         /* DLYBS is mostly irrelevant since we manage chipselect using GPIOs.
 614          *
 615          * DLYBCT would add delays between words, slowing down transfers.
 616          * It could potentially be useful to cope with DMA bottlenecks, but
 617          * in those cases it's probably best to just use a lower bitrate.
 618          */
 619         csr |= SPI_BF(DLYBS, 0);
 620         csr |= SPI_BF(DLYBCT, 0);
 621
 622         /* chipselect must have been muxed as GPIO (e.g. in board setup) */
 623         npcs_pin = (unsigned int)spi->controller_data;
 624         asd = spi->controller_state;
 625         if (!asd) {
 626                 asd = kzalloc(sizeof(struct atmel_spi_device), GFP_KERNEL);
 627                 if (!asd)
 628                         return -ENOMEM;
 629
 630                 ret = gpio_request(npcs_pin, spi->dev.bus_id);
 631                 if (ret) {
 632                         kfree(asd);
 633                         return ret;
 634                 }
 635
 636                 asd->npcs_pin = npcs_pin;
 637                 spi->controller_state = asd;
 638                 gpio_direction_output(npcs_pin, !(spi->mode & SPI_CS_HIGH));
 639         } else {
 640                 unsigned long           flags;
 641
 642                 spin_lock_irqsave(&as->lock, flags);
 643                 if (as->stay == spi)
 644                         as->stay = NULL;
 645                 cs_deactivate(as, spi);
 646                 spin_unlock_irqrestore(&as->lock, flags);
 647         }
 648
 649         asd->csr = csr;
 650
 651         dev_dbg(&spi->dev,
 652                 "setup: %lu Hz bpw %u mode 0x%x -> csr%d %08x\n",
 653                 bus_hz / scbr, bits, spi->mode, spi->chip_select, csr);
 654
 655         if (!atmel_spi_is_v2())
 656                 spi_writel(as, CSR0 + 4 * spi->chip_select, csr);
 657
 658         return 0;
 659 }
 660
 661 static int atmel_spi_transfer(struct spi_device *spi, struct spi_message *msg)
 662 {
 663         struct atmel_spi        *as;
 664         struct spi_transfer     *xfer;
 665         unsigned long           flags;
 666         struct device           *controller = spi->master->dev.parent;
 667
 668         as = spi_master_get_devdata(spi->master);
 669
 670         dev_dbg(controller, "new message %p submitted for %s\n",
 671                         msg, spi->dev.bus_id);
 672
 673         if (unlikely(list_empty(&msg->transfers)
 674                         || !spi->max_speed_hz))
 675                 return -EINVAL;
 676
 677         if (as->stopping)
 678                 return -ESHUTDOWN;
 679
 680         list_for_each_entry(xfer, &msg->transfers, transfer_list) {
 681                 if (!(xfer->tx_buf || xfer->rx_buf) && xfer->len) {
 682                         dev_dbg(&spi->dev, "missing rx or tx buf\n");
 683                         return -EINVAL;
 684                 }
 685
 686                 /* FIXME implement these protocol options!! */
 687                 if (xfer->bits_per_word || xfer->speed_hz) {
 688                         dev_dbg(&spi->dev, "no protocol options yet\n");
 689                         return -ENOPROTOOPT;
 690                 }
 691
 692                 /*
 693                  * DMA map early, for performance (empties dcache ASAP) and
 694                  * better fault reporting.  This is a DMA-only driver.
 695                  *
 696                  * NOTE that if dma_unmap_single() ever starts to do work on
 697                  * platforms supported by this driver, we would need to clean
 698                  * up mappings for previously-mapped transfers.
 699                  */
 700                 if (!msg->is_dma_mapped) {
 701                         if (atmel_spi_dma_map_xfer(as, xfer) < 0)
 702                                 return -ENOMEM;
 703                 }
 704         }
 705
 706 #ifdef VERBOSE
 707         list_for_each_entry(xfer, &msg->transfers, transfer_list) {
 708                 dev_dbg(controller,
 709                         "  xfer %p: len %u tx %p/%08x rx %p/%08x\n",
 710                         xfer, xfer->len,
 711                         xfer->tx_buf, xfer->tx_dma,
 712                         xfer->rx_buf, xfer->rx_dma);
 713         }
 714 #endif
 715
 716         msg->status = -EINPROGRESS;
 717         msg->actual_length = 0;
 718
 719         spin_lock_irqsave(&as->lock, flags);
 720         list_add_tail(&msg->queue, &as->queue);
 721         if (!as->current_transfer)
 722                 atmel_spi_next_message(spi->master);
 723         spin_unlock_irqrestore(&as->lock, flags);
 724
 725         return 0;
 726 }
 727
 728 static void atmel_spi_cleanup(struct spi_device *spi)
 729 {
 730         struct atmel_spi        *as = spi_master_get_devdata(spi->master);
 731         struct atmel_spi_device *asd = spi->controller_state;
 732         unsigned                gpio = (unsigned) spi->controller_data;
 733         unsigned long           flags;
 734
 735         if (!asd)
 736                 return;
 737
 738         spin_lock_irqsave(&as->lock, flags);
 739         if (as->stay == spi) {
 740                 as->stay = NULL;
 741                 cs_deactivate(as, spi);
 742         }
 743         spin_unlock_irqrestore(&as->lock, flags);
 744
 745         spi->controller_state = NULL;
 746         gpio_free(gpio);
 747         kfree(asd);
 748 }
 749
 750 /*-------------------------------------------------------------------------*/
 751
 752 static int __init atmel_spi_probe(struct platform_device *pdev)
 753 {
 754         struct resource         *regs;
 755         int                     irq;
 756         struct clk              *clk;
 757         int                     ret;
 758         struct spi_master       *master;
 759         struct atmel_spi        *as;
 760
 761         regs = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 762         if (!regs)
 763                 return -ENXIO;
 764
 765         irq = platform_get_irq(pdev, 0);
 766         if (irq < 0)
 767                 return irq;
 768
 769         clk = clk_get(&pdev->dev, "spi_clk");
 770         if (IS_ERR(clk))
 771                 return PTR_ERR(clk);
 772
 773         /* setup spi core then atmel-specific driver state */
 774         ret = -ENOMEM;
 775         master = spi_alloc_master(&pdev->dev, sizeof *as);
 776         if (!master)
 777                 goto out_free;
 778
 779         master->bus_num = pdev->id;
 780         master->num_chipselect = 4;
 781         master->setup = atmel_spi_setup;
 782         master->transfer = atmel_spi_transfer;
 783         master->cleanup = atmel_spi_cleanup;
 784         platform_set_drvdata(pdev, master);
 785
 786         as = spi_master_get_devdata(master);
 787
 788         /*
 789          * Scratch buffer is used for throwaway rx and tx data.
 790          * It's coherent to minimize dcache pollution.
 791          */
 792         as->buffer = dma_alloc_coherent(&pdev->dev, BUFFER_SIZE,
 793                                         &as->buffer_dma, GFP_KERNEL);
 794         if (!as->buffer)
 795                 goto out_free;
 796
 797         spin_lock_init(&as->lock);
 798         INIT_LIST_HEAD(&as->queue);
 799         as->pdev = pdev;
 800         as->regs = ioremap(regs->start, (regs->end - regs->start) + 1);
 801         if (!as->regs)
 802                 goto out_free_buffer;
 803         as->irq = irq;
 804         as->clk = clk;
 805
 806         ret = request_irq(irq, atmel_spi_interrupt, 0,
 807                         pdev->dev.bus_id, master);
 808         if (ret)
 809                 goto out_unmap_regs;
 810
 811         /* Initialize the hardware */
 812         clk_enable(clk);
 813         spi_writel(as, CR, SPI_BIT(SWRST));
 814         spi_writel(as, CR, SPI_BIT(SWRST)); /* AT91SAM9263 Rev B workaround */
 815         spi_writel(as, MR, SPI_BIT(MSTR) | SPI_BIT(MODFDIS));
 816         spi_writel(as, PTCR, SPI_BIT(RXTDIS) | SPI_BIT(TXTDIS));
 817         spi_writel(as, CR, SPI_BIT(SPIEN));
 818
 819         /* go! */
 820         dev_info(&pdev->dev, "Atmel SPI Controller at 0x%08lx (irq %d)\n",
 821                         (unsigned long)regs->start, irq);
 822
 823         ret = spi_register_master(master);
 824         if (ret)
 825                 goto out_reset_hw;
 826
 827         return 0;
 828
 829 out_reset_hw:
 830         spi_writel(as, CR, SPI_BIT(SWRST));
 831         spi_writel(as, CR, SPI_BIT(SWRST)); /* AT91SAM9263 Rev B workaround */
 832         clk_disable(clk);
 833         free_irq(irq, master);
 834 out_unmap_regs:
 835         iounmap(as->regs);
 836 out_free_buffer:
 837         dma_free_coherent(&pdev->dev, BUFFER_SIZE, as->buffer,
 838                         as->buffer_dma);
 839 out_free:
 840         clk_put(clk);
 841         spi_master_put(master);
 842         return ret;
 843 }
 844
 845 static int __exit atmel_spi_remove(struct platform_device *pdev)
 846 {
 847         struct spi_master       *master = platform_get_drvdata(pdev);
 848         struct atmel_spi        *as = spi_master_get_devdata(master);
 849         struct spi_message      *msg;
 850
 851         /* reset the hardware and block queue progress */
 852         spin_lock_irq(&as->lock);
 853         as->stopping = 1;
 854         spi_writel(as, CR, SPI_BIT(SWRST));
 855         spi_writel(as, CR, SPI_BIT(SWRST)); /* AT91SAM9263 Rev B workaround */
 856         spi_readl(as, SR);
 857         spin_unlock_irq(&as->lock);
 858
 859         /* Terminate remaining queued transfers */
 860         list_for_each_entry(msg, &as->queue, queue) {
 861                 /* REVISIT unmapping the dma is a NOP on ARM and AVR32
 862                  * but we shouldn't depend on that...
 863                  */
 864                 msg->status = -ESHUTDOWN;
 865                 msg->complete(msg->context);
 866         }
 867
 868         dma_free_coherent(&pdev->dev, BUFFER_SIZE, as->buffer,
 869                         as->buffer_dma);
 870
 871         clk_disable(as->clk);
 872         clk_put(as->clk);
 873         free_irq(as->irq, master);
 874         iounmap(as->regs);
 875
 876         spi_unregister_master(master);
 877
 878         return 0;
 879 }
 880
 881 #ifdef  CONFIG_PM
 882
 883 static int atmel_spi_suspend(struct platform_device *pdev, pm_message_t mesg)
 884 {
 885         struct spi_master       *master = platform_get_drvdata(pdev);
 886         struct atmel_spi        *as = spi_master_get_devdata(master);
 887
 888         clk_disable(as->clk);
 889         return 0;
 890 }
 891
 892 static int atmel_spi_resume(struct platform_device *pdev)
 893 {
 894         struct spi_master       *master = platform_get_drvdata(pdev);
 895         struct atmel_spi        *as = spi_master_get_devdata(master);
 896
 897         clk_enable(as->clk);
 898         return 0;
 899 }
 900
 901 #else
 902 #define atmel_spi_suspend       NULL
 903 #define atmel_spi_resume        NULL
 904 #endif
 905
 906
 907 static struct platform_driver atmel_spi_driver = {
 908         .driver         = {
 909                 .name   = "atmel_spi",
 910                 .owner  = THIS_MODULE,
 911         },
 912         .suspend        = atmel_spi_suspend,
 913         .resume         = atmel_spi_resume,
 914         .remove         = __exit_p(atmel_spi_remove),
 915 };
 916
 917 static int __init atmel_spi_init(void)
 918 {
 919         return platform_driver_probe(&atmel_spi_driver, atmel_spi_probe);
 920 }
 921 module_init(atmel_spi_init);
 922
 923 static void __exit atmel_spi_exit(void)
 924 {
 925         platform_driver_unregister(&atmel_spi_driver);
 926 }
 927 module_exit(atmel_spi_exit);
 928
 929 MODULE_DESCRIPTION("Atmel AT32/AT91 SPI Controller driver");
 930 MODULE_AUTHOR("Haavard Skinnemoen <hskinnemoen@atmel.com>");
 931 MODULE_LICENSE("GPL");
 932 MODULE_ALIAS("platform:atmel_spi");