drivers/spi/spi-atmel.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 #include <linux/slab.h>
  22 #include <linux/platform_data/atmel.h>
  23 #include <linux/of.h>
  24
  25 #include <asm/io.h>
  26 #include <asm/gpio.h>
  27 #include <mach/cpu.h>
  28
  29 /* SPI register offsets */
  30 #define SPI_CR                                  0x0000
  31 #define SPI_MR                                  0x0004
  32 #define SPI_RDR                                 0x0008
  33 #define SPI_TDR                                 0x000c
  34 #define SPI_SR                                  0x0010
  35 #define SPI_IER                                 0x0014
  36 #define SPI_IDR                                 0x0018
  37 #define SPI_IMR                                 0x001c
  38 #define SPI_CSR0                                0x0030
  39 #define SPI_CSR1                                0x0034
  40 #define SPI_CSR2                                0x0038
  41 #define SPI_CSR3                                0x003c
  42 #define SPI_RPR                                 0x0100
  43 #define SPI_RCR                                 0x0104
  44 #define SPI_TPR                                 0x0108
  45 #define SPI_TCR                                 0x010c
  46 #define SPI_RNPR                                0x0110
  47 #define SPI_RNCR                                0x0114
  48 #define SPI_TNPR                                0x0118
  49 #define SPI_TNCR                                0x011c
  50 #define SPI_PTCR                                0x0120
  51 #define SPI_PTSR                                0x0124
  52
  53 /* Bitfields in CR */
  54 #define SPI_SPIEN_OFFSET                        0
  55 #define SPI_SPIEN_SIZE                          1
  56 #define SPI_SPIDIS_OFFSET                       1
  57 #define SPI_SPIDIS_SIZE                         1
  58 #define SPI_SWRST_OFFSET                        7
  59 #define SPI_SWRST_SIZE                          1
  60 #define SPI_LASTXFER_OFFSET                     24
  61 #define SPI_LASTXFER_SIZE                       1
  62
  63 /* Bitfields in MR */
  64 #define SPI_MSTR_OFFSET                         0
  65 #define SPI_MSTR_SIZE                           1
  66 #define SPI_PS_OFFSET                           1
  67 #define SPI_PS_SIZE                             1
  68 #define SPI_PCSDEC_OFFSET                       2
  69 #define SPI_PCSDEC_SIZE                         1
  70 #define SPI_FDIV_OFFSET                         3
  71 #define SPI_FDIV_SIZE                           1
  72 #define SPI_MODFDIS_OFFSET                      4
  73 #define SPI_MODFDIS_SIZE                        1
  74 #define SPI_LLB_OFFSET                          7
  75 #define SPI_LLB_SIZE                            1
  76 #define SPI_PCS_OFFSET                          16
  77 #define SPI_PCS_SIZE                            4
  78 #define SPI_DLYBCS_OFFSET                       24
  79 #define SPI_DLYBCS_SIZE                         8
  80
  81 /* Bitfields in RDR */
  82 #define SPI_RD_OFFSET                           0
  83 #define SPI_RD_SIZE                             16
  84
  85 /* Bitfields in TDR */
  86 #define SPI_TD_OFFSET                           0
  87 #define SPI_TD_SIZE                             16
  88
  89 /* Bitfields in SR */
  90 #define SPI_RDRF_OFFSET                         0
  91 #define SPI_RDRF_SIZE                           1
  92 #define SPI_TDRE_OFFSET                         1
  93 #define SPI_TDRE_SIZE                           1
  94 #define SPI_MODF_OFFSET                         2
  95 #define SPI_MODF_SIZE                           1
  96 #define SPI_OVRES_OFFSET                        3
  97 #define SPI_OVRES_SIZE                          1
  98 #define SPI_ENDRX_OFFSET                        4
  99 #define SPI_ENDRX_SIZE                          1
 100 #define SPI_ENDTX_OFFSET                        5
 101 #define SPI_ENDTX_SIZE                          1
 102 #define SPI_RXBUFF_OFFSET                       6
 103 #define SPI_RXBUFF_SIZE                         1
 104 #define SPI_TXBUFE_OFFSET                       7
 105 #define SPI_TXBUFE_SIZE                         1
 106 #define SPI_NSSR_OFFSET                         8
 107 #define SPI_NSSR_SIZE                           1
 108 #define SPI_TXEMPTY_OFFSET                      9
 109 #define SPI_TXEMPTY_SIZE                        1
 110 #define SPI_SPIENS_OFFSET                       16
 111 #define SPI_SPIENS_SIZE                         1
 112
 113 /* Bitfields in CSR0 */
 114 #define SPI_CPOL_OFFSET                         0
 115 #define SPI_CPOL_SIZE                           1
 116 #define SPI_NCPHA_OFFSET                        1
 117 #define SPI_NCPHA_SIZE                          1
 118 #define SPI_CSAAT_OFFSET                        3
 119 #define SPI_CSAAT_SIZE                          1
 120 #define SPI_BITS_OFFSET                         4
 121 #define SPI_BITS_SIZE                           4
 122 #define SPI_SCBR_OFFSET                         8
 123 #define SPI_SCBR_SIZE                           8
 124 #define SPI_DLYBS_OFFSET                        16
 125 #define SPI_DLYBS_SIZE                          8
 126 #define SPI_DLYBCT_OFFSET                       24
 127 #define SPI_DLYBCT_SIZE                         8
 128
 129 /* Bitfields in RCR */
 130 #define SPI_RXCTR_OFFSET                        0
 131 #define SPI_RXCTR_SIZE                          16
 132
 133 /* Bitfields in TCR */
 134 #define SPI_TXCTR_OFFSET                        0
 135 #define SPI_TXCTR_SIZE                          16
 136
 137 /* Bitfields in RNCR */
 138 #define SPI_RXNCR_OFFSET                        0
 139 #define SPI_RXNCR_SIZE                          16
 140
 141 /* Bitfields in TNCR */
 142 #define SPI_TXNCR_OFFSET                        0
 143 #define SPI_TXNCR_SIZE                          16
 144
 145 /* Bitfields in PTCR */
 146 #define SPI_RXTEN_OFFSET                        0
 147 #define SPI_RXTEN_SIZE                          1
 148 #define SPI_RXTDIS_OFFSET                       1
 149 #define SPI_RXTDIS_SIZE                         1
 150 #define SPI_TXTEN_OFFSET                        8
 151 #define SPI_TXTEN_SIZE                          1
 152 #define SPI_TXTDIS_OFFSET                       9
 153 #define SPI_TXTDIS_SIZE                         1
 154
 155 /* Constants for BITS */
 156 #define SPI_BITS_8_BPT                          0
 157 #define SPI_BITS_9_BPT                          1
 158 #define SPI_BITS_10_BPT                         2
 159 #define SPI_BITS_11_BPT                         3
 160 #define SPI_BITS_12_BPT                         4
 161 #define SPI_BITS_13_BPT                         5
 162 #define SPI_BITS_14_BPT                         6
 163 #define SPI_BITS_15_BPT                         7
 164 #define SPI_BITS_16_BPT                         8
 165
 166 /* Bit manipulation macros */
 167 #define SPI_BIT(name) \
 168         (1 << SPI_##name##_OFFSET)
 169 #define SPI_BF(name,value) \
 170         (((value) & ((1 << SPI_##name##_SIZE) - 1)) << SPI_##name##_OFFSET)
 171 #define SPI_BFEXT(name,value) \
 172         (((value) >> SPI_##name##_OFFSET) & ((1 << SPI_##name##_SIZE) - 1))
 173 #define SPI_BFINS(name,value,old) \
 174         ( ((old) & ~(((1 << SPI_##name##_SIZE) - 1) << SPI_##name##_OFFSET)) \
 175           | SPI_BF(name,value))
 176
 177 /* Register access macros */
 178 #define spi_readl(port,reg) \
 179         __raw_readl((port)->regs + SPI_##reg)
 180 #define spi_writel(port,reg,value) \
 181         __raw_writel((value), (port)->regs + SPI_##reg)
 182
 183
 184 /*
 185  * The core SPI transfer engine just talks to a register bank to set up
 186  * DMA transfers; transfer queue progress is driven by IRQs.  The clock
 187  * framework provides the base clock, subdivided for each spi_device.
 188  */
 189 struct atmel_spi {
 190         spinlock_t              lock;
 191
 192         void __iomem            *regs;
 193         int                     irq;
 194         struct clk              *clk;
 195         struct platform_device  *pdev;
 196         struct spi_device       *stay;
 197
 198         u8                      stopping;
 199         struct list_head        queue;
 200         struct spi_transfer     *current_transfer;
 201         unsigned long           current_remaining_bytes;
 202         struct spi_transfer     *next_transfer;
 203         unsigned long           next_remaining_bytes;
 204
 205         void                    *buffer;
 206         dma_addr_t              buffer_dma;
 207 };
 208
 209 /* Controller-specific per-slave state */
 210 struct atmel_spi_device {
 211         unsigned int            npcs_pin;
 212         u32                     csr;
 213 };
 214
 215 #define BUFFER_SIZE             PAGE_SIZE
 216 #define INVALID_DMA_ADDRESS     0xffffffff
 217
 218 /*
 219  * Version 2 of the SPI controller has
 220  *  - CR.LASTXFER
 221  *  - SPI_MR.DIV32 may become FDIV or must-be-zero (here: always zero)
 222  *  - SPI_SR.TXEMPTY, SPI_SR.NSSR (and corresponding irqs)
 223  *  - SPI_CSRx.CSAAT
 224  *  - SPI_CSRx.SBCR allows faster clocking
 225  *
 226  * We can determine the controller version by reading the VERSION
 227  * register, but I haven't checked that it exists on all chips, and
 228  * this is cheaper anyway.
 229  */
 230 static bool atmel_spi_is_v2(void)
 231 {
 232         return !cpu_is_at91rm9200();
 233 }
 234
 235 /*
 236  * Earlier SPI controllers (e.g. on at91rm9200) have a design bug whereby
 237  * they assume that spi slave device state will not change on deselect, so
 238  * that automagic deselection is OK.  ("NPCSx rises if no data is to be
 239  * transmitted")  Not so!  Workaround uses nCSx pins as GPIOs; or newer
 240  * controllers have CSAAT and friends.
 241  *
 242  * Since the CSAAT functionality is a bit weird on newer controllers as
 243  * well, we use GPIO to control nCSx pins on all controllers, updating
 244  * MR.PCS to avoid confusing the controller.  Using GPIOs also lets us
 245  * support active-high chipselects despite the controller's belief that
 246  * only active-low devices/systems exists.
 247  *
 248  * However, at91rm9200 has a second erratum whereby nCS0 doesn't work
 249  * right when driven with GPIO.  ("Mode Fault does not allow more than one
 250  * Master on Chip Select 0.")  No workaround exists for that ... so for
 251  * nCS0 on that chip, we (a) don't use the GPIO, (b) can't support CS_HIGH,
 252  * and (c) will trigger that first erratum in some cases.
 253  *
 254  * TODO: Test if the atmel_spi_is_v2() branch below works on
 255  * AT91RM9200 if we use some other register than CSR0. However, don't
 256  * do this unconditionally since AP7000 has an errata where the BITS
 257  * field in CSR0 overrides all other CSRs.
 258  */
 259
 260 static void cs_activate(struct atmel_spi *as, struct spi_device *spi)
 261 {
 262         struct atmel_spi_device *asd = spi->controller_state;
 263         unsigned active = spi->mode & SPI_CS_HIGH;
 264         u32 mr;
 265
 266         if (atmel_spi_is_v2()) {
 267                 /*
 268                  * Always use CSR0. This ensures that the clock
 269                  * switches to the correct idle polarity before we
 270                  * toggle the CS.
 271                  */
 272                 spi_writel(as, CSR0, asd->csr);
 273                 spi_writel(as, MR, SPI_BF(PCS, 0x0e) | SPI_BIT(MODFDIS)
 274                                 | SPI_BIT(MSTR));
 275                 mr = spi_readl(as, MR);
 276                 gpio_set_value(asd->npcs_pin, active);
 277         } else {
 278                 u32 cpol = (spi->mode & SPI_CPOL) ? SPI_BIT(CPOL) : 0;
 279                 int i;
 280                 u32 csr;
 281
 282                 /* Make sure clock polarity is correct */
 283                 for (i = 0; i < spi->master->num_chipselect; i++) {
 284                         csr = spi_readl(as, CSR0 + 4 * i);
 285                         if ((csr ^ cpol) & SPI_BIT(CPOL))
 286                                 spi_writel(as, CSR0 + 4 * i,
 287                                                 csr ^ SPI_BIT(CPOL));
 288                 }
 289
 290                 mr = spi_readl(as, MR);
 291                 mr = SPI_BFINS(PCS, ~(1 << spi->chip_select), mr);
 292                 if (spi->chip_select != 0)
 293                         gpio_set_value(asd->npcs_pin, active);
 294                 spi_writel(as, MR, mr);
 295         }
 296
 297         dev_dbg(&spi->dev, "activate %u%s, mr %08x\n",
 298                         asd->npcs_pin, active ? " (high)" : "",
 299                         mr);
 300 }
 301
 302 static void cs_deactivate(struct atmel_spi *as, struct spi_device *spi)
 303 {
 304         struct atmel_spi_device *asd = spi->controller_state;
 305         unsigned active = spi->mode & SPI_CS_HIGH;
 306         u32 mr;
 307
 308         /* only deactivate *this* device; sometimes transfers to
 309          * another device may be active when this routine is called.
 310          */
 311         mr = spi_readl(as, MR);
 312         if (~SPI_BFEXT(PCS, mr) & (1 << spi->chip_select)) {
 313                 mr = SPI_BFINS(PCS, 0xf, mr);
 314                 spi_writel(as, MR, mr);
 315         }
 316
 317         dev_dbg(&spi->dev, "DEactivate %u%s, mr %08x\n",
 318                         asd->npcs_pin, active ? " (low)" : "",
 319                         mr);
 320
 321         if (atmel_spi_is_v2() || spi->chip_select != 0)
 322                 gpio_set_value(asd->npcs_pin, !active);
 323 }
 324
 325 static inline int atmel_spi_xfer_is_last(struct spi_message *msg,
 326                                         struct spi_transfer *xfer)
 327 {
 328         return msg->transfers.prev == &xfer->transfer_list;
 329 }
 330
 331 static inline int atmel_spi_xfer_can_be_chained(struct spi_transfer *xfer)
 332 {
 333         return xfer->delay_usecs == 0 && !xfer->cs_change;
 334 }
 335
 336 static void atmel_spi_next_xfer_data(struct spi_master *master,
 337                                 struct spi_transfer *xfer,
 338                                 dma_addr_t *tx_dma,
 339                                 dma_addr_t *rx_dma,
 340                                 u32 *plen)
 341 {
 342         struct atmel_spi        *as = spi_master_get_devdata(master);
 343         u32                     len = *plen;
 344
 345         /* use scratch buffer only when rx or tx data is unspecified */
 346         if (xfer->rx_buf)
 347                 *rx_dma = xfer->rx_dma + xfer->len - *plen;
 348         else {
 349                 *rx_dma = as->buffer_dma;
 350                 if (len > BUFFER_SIZE)
 351                         len = BUFFER_SIZE;
 352         }
 353         if (xfer->tx_buf)
 354                 *tx_dma = xfer->tx_dma + xfer->len - *plen;
 355         else {
 356                 *tx_dma = as->buffer_dma;
 357                 if (len > BUFFER_SIZE)
 358                         len = BUFFER_SIZE;
 359                 memset(as->buffer, 0, len);
 360                 dma_sync_single_for_device(&as->pdev->dev,
 361                                 as->buffer_dma, len, DMA_TO_DEVICE);
 362         }
 363
 364         *plen = len;
 365 }
 366
 367 /*
 368  * Submit next transfer for DMA.
 369  * lock is held, spi irq is blocked
 370  */
 371 static void atmel_spi_next_xfer(struct spi_master *master,
 372                                 struct spi_message *msg)
 373 {
 374         struct atmel_spi        *as = spi_master_get_devdata(master);
 375         struct spi_transfer     *xfer;
 376         u32                     len, remaining;
 377         u32                     ieval;
 378         dma_addr_t              tx_dma, rx_dma;
 379
 380         if (!as->current_transfer)
 381                 xfer = list_entry(msg->transfers.next,
 382                                 struct spi_transfer, transfer_list);
 383         else if (!as->next_transfer)
 384                 xfer = list_entry(as->current_transfer->transfer_list.next,
 385                                 struct spi_transfer, transfer_list);
 386         else
 387                 xfer = NULL;
 388
 389         if (xfer) {
 390                 spi_writel(as, PTCR, SPI_BIT(RXTDIS) | SPI_BIT(TXTDIS));
 391
 392                 len = xfer->len;
 393                 atmel_spi_next_xfer_data(master, xfer, &tx_dma, &rx_dma, &len);
 394                 remaining = xfer->len - len;
 395
 396                 spi_writel(as, RPR, rx_dma);
 397                 spi_writel(as, TPR, tx_dma);
 398
 399                 if (msg->spi->bits_per_word > 8)
 400                         len >>= 1;
 401                 spi_writel(as, RCR, len);
 402                 spi_writel(as, TCR, len);
 403
 404                 dev_dbg(&msg->spi->dev,
 405                         "  start xfer %p: len %u tx %p/%08x rx %p/%08x\n",
 406                         xfer, xfer->len, xfer->tx_buf, xfer->tx_dma,
 407                         xfer->rx_buf, xfer->rx_dma);
 408         } else {
 409                 xfer = as->next_transfer;
 410                 remaining = as->next_remaining_bytes;
 411         }
 412
 413         as->current_transfer = xfer;
 414         as->current_remaining_bytes = remaining;
 415
 416         if (remaining > 0)
 417                 len = remaining;
 418         else if (!atmel_spi_xfer_is_last(msg, xfer)
 419                         && atmel_spi_xfer_can_be_chained(xfer)) {
 420                 xfer = list_entry(xfer->transfer_list.next,
 421                                 struct spi_transfer, transfer_list);
 422                 len = xfer->len;
 423         } else
 424                 xfer = NULL;
 425
 426         as->next_transfer = xfer;
 427
 428         if (xfer) {
 429                 u32     total;
 430
 431                 total = len;
 432                 atmel_spi_next_xfer_data(master, xfer, &tx_dma, &rx_dma, &len);
 433                 as->next_remaining_bytes = total - len;
 434
 435                 spi_writel(as, RNPR, rx_dma);
 436                 spi_writel(as, TNPR, tx_dma);
 437
 438                 if (msg->spi->bits_per_word > 8)
 439                         len >>= 1;
 440                 spi_writel(as, RNCR, len);
 441                 spi_writel(as, TNCR, len);
 442
 443                 dev_dbg(&msg->spi->dev,
 444                         "  next xfer %p: len %u tx %p/%08x rx %p/%08x\n",
 445                         xfer, xfer->len, xfer->tx_buf, xfer->tx_dma,
 446                         xfer->rx_buf, xfer->rx_dma);
 447                 ieval = SPI_BIT(ENDRX) | SPI_BIT(OVRES);
 448         } else {
 449                 spi_writel(as, RNCR, 0);
 450                 spi_writel(as, TNCR, 0);
 451                 ieval = SPI_BIT(RXBUFF) | SPI_BIT(ENDRX) | SPI_BIT(OVRES);
 452         }
 453
 454         /* REVISIT: We're waiting for ENDRX before we start the next
 455          * transfer because we need to handle some difficult timing
 456          * issues otherwise. If we wait for ENDTX in one transfer and
 457          * then starts waiting for ENDRX in the next, it's difficult
 458          * to tell the difference between the ENDRX interrupt we're
 459          * actually waiting for and the ENDRX interrupt of the
 460          * previous transfer.
 461          *
 462          * It should be doable, though. Just not now...
 463          */
 464         spi_writel(as, IER, ieval);
 465         spi_writel(as, PTCR, SPI_BIT(TXTEN) | SPI_BIT(RXTEN));
 466 }
 467
 468 static void atmel_spi_next_message(struct spi_master *master)
 469 {
 470         struct atmel_spi        *as = spi_master_get_devdata(master);
 471         struct spi_message      *msg;
 472         struct spi_device       *spi;
 473
 474         BUG_ON(as->current_transfer);
 475
 476         msg = list_entry(as->queue.next, struct spi_message, queue);
 477         spi = msg->spi;
 478
 479         dev_dbg(master->dev.parent, "start message %p for %s\n",
 480                         msg, dev_name(&spi->dev));
 481
 482         /* select chip if it's not still active */
 483         if (as->stay) {
 484                 if (as->stay != spi) {
 485                         cs_deactivate(as, as->stay);
 486                         cs_activate(as, spi);
 487                 }
 488                 as->stay = NULL;
 489         } else
 490                 cs_activate(as, spi);
 491
 492         atmel_spi_next_xfer(master, msg);
 493 }
 494
 495 /*
 496  * For DMA, tx_buf/tx_dma have the same relationship as rx_buf/rx_dma:
 497  *  - The buffer is either valid for CPU access, else NULL
 498  *  - If the buffer is valid, so is its DMA address
 499  *
 500  * This driver manages the dma address unless message->is_dma_mapped.
 501  */
 502 static int
 503 atmel_spi_dma_map_xfer(struct atmel_spi *as, struct spi_transfer *xfer)
 504 {
 505         struct device   *dev = &as->pdev->dev;
 506
 507         xfer->tx_dma = xfer->rx_dma = INVALID_DMA_ADDRESS;
 508         if (xfer->tx_buf) {
 509                 /* tx_buf is a const void* where we need a void * for the dma
 510                  * mapping */
 511                 void *nonconst_tx = (void *)xfer->tx_buf;
 512
 513                 xfer->tx_dma = dma_map_single(dev,
 514                                 nonconst_tx, xfer->len,
 515                                 DMA_TO_DEVICE);
 516                 if (dma_mapping_error(dev, xfer->tx_dma))
 517                         return -ENOMEM;
 518         }
 519         if (xfer->rx_buf) {
 520                 xfer->rx_dma = dma_map_single(dev,
 521                                 xfer->rx_buf, xfer->len,
 522                                 DMA_FROM_DEVICE);
 523                 if (dma_mapping_error(dev, xfer->rx_dma)) {
 524                         if (xfer->tx_buf)
 525                                 dma_unmap_single(dev,
 526                                                 xfer->tx_dma, xfer->len,
 527                                                 DMA_TO_DEVICE);
 528                         return -ENOMEM;
 529                 }
 530         }
 531         return 0;
 532 }
 533
 534 static void atmel_spi_dma_unmap_xfer(struct spi_master *master,
 535                                      struct spi_transfer *xfer)
 536 {
 537         if (xfer->tx_dma != INVALID_DMA_ADDRESS)
 538                 dma_unmap_single(master->dev.parent, xfer->tx_dma,
 539                                  xfer->len, DMA_TO_DEVICE);
 540         if (xfer->rx_dma != INVALID_DMA_ADDRESS)
 541                 dma_unmap_single(master->dev.parent, xfer->rx_dma,
 542                                  xfer->len, DMA_FROM_DEVICE);
 543 }
 544
 545 static void
 546 atmel_spi_msg_done(struct spi_master *master, struct atmel_spi *as,
 547                 struct spi_message *msg, int status, int stay)
 548 {
 549         if (!stay || status < 0)
 550                 cs_deactivate(as, msg->spi);
 551         else
 552                 as->stay = msg->spi;
 553
 554         list_del(&msg->queue);
 555         msg->status = status;
 556
 557         dev_dbg(master->dev.parent,
 558                 "xfer complete: %u bytes transferred\n",
 559                 msg->actual_length);
 560
 561         spin_unlock(&as->lock);
 562         msg->complete(msg->context);
 563         spin_lock(&as->lock);
 564
 565         as->current_transfer = NULL;
 566         as->next_transfer = NULL;
 567
 568         /* continue if needed */
 569         if (list_empty(&as->queue) || as->stopping)
 570                 spi_writel(as, PTCR, SPI_BIT(RXTDIS) | SPI_BIT(TXTDIS));
 571         else
 572                 atmel_spi_next_message(master);
 573 }
 574
 575 static irqreturn_t
 576 atmel_spi_interrupt(int irq, void *dev_id)
 577 {
 578         struct spi_master       *master = dev_id;
 579         struct atmel_spi        *as = spi_master_get_devdata(master);
 580         struct spi_message      *msg;
 581         struct spi_transfer     *xfer;
 582         u32                     status, pending, imr;
 583         int                     ret = IRQ_NONE;
 584
 585         spin_lock(&as->lock);
 586
 587         xfer = as->current_transfer;
 588         msg = list_entry(as->queue.next, struct spi_message, queue);
 589
 590         imr = spi_readl(as, IMR);
 591         status = spi_readl(as, SR);
 592         pending = status & imr;
 593
 594         if (pending & SPI_BIT(OVRES)) {
 595                 int timeout;
 596
 597                 ret = IRQ_HANDLED;
 598
 599                 spi_writel(as, IDR, (SPI_BIT(RXBUFF) | SPI_BIT(ENDRX)
 600                                      | SPI_BIT(OVRES)));
 601
 602                 /*
 603                  * When we get an overrun, we disregard the current
 604                  * transfer. Data will not be copied back from any
 605                  * bounce buffer and msg->actual_len will not be
 606                  * updated with the last xfer.
 607                  *
 608                  * We will also not process any remaning transfers in
 609                  * the message.
 610                  *
 611                  * First, stop the transfer and unmap the DMA buffers.
 612                  */
 613                 spi_writel(as, PTCR, SPI_BIT(RXTDIS) | SPI_BIT(TXTDIS));
 614                 if (!msg->is_dma_mapped)
 615                         atmel_spi_dma_unmap_xfer(master, xfer);
 616
 617                 /* REVISIT: udelay in irq is unfriendly */
 618                 if (xfer->delay_usecs)
 619                         udelay(xfer->delay_usecs);
 620
 621                 dev_warn(master->dev.parent, "overrun (%u/%u remaining)\n",
 622                          spi_readl(as, TCR), spi_readl(as, RCR));
 623
 624                 /*
 625                  * Clean up DMA registers and make sure the data
 626                  * registers are empty.
 627                  */
 628                 spi_writel(as, RNCR, 0);
 629                 spi_writel(as, TNCR, 0);
 630                 spi_writel(as, RCR, 0);
 631                 spi_writel(as, TCR, 0);
 632                 for (timeout = 1000; timeout; timeout--)
 633                         if (spi_readl(as, SR) & SPI_BIT(TXEMPTY))
 634                                 break;
 635                 if (!timeout)
 636                         dev_warn(master->dev.parent,
 637                                  "timeout waiting for TXEMPTY");
 638                 while (spi_readl(as, SR) & SPI_BIT(RDRF))
 639                         spi_readl(as, RDR);
 640
 641                 /* Clear any overrun happening while cleaning up */
 642                 spi_readl(as, SR);
 643
 644                 atmel_spi_msg_done(master, as, msg, -EIO, 0);
 645         } else if (pending & (SPI_BIT(RXBUFF) | SPI_BIT(ENDRX))) {
 646                 ret = IRQ_HANDLED;
 647
 648                 spi_writel(as, IDR, pending);
 649
 650                 if (as->current_remaining_bytes == 0) {
 651                         msg->actual_length += xfer->len;
 652
 653                         if (!msg->is_dma_mapped)
 654                                 atmel_spi_dma_unmap_xfer(master, xfer);
 655
 656                         /* REVISIT: udelay in irq is unfriendly */
 657                         if (xfer->delay_usecs)
 658                                 udelay(xfer->delay_usecs);
 659
 660                         if (atmel_spi_xfer_is_last(msg, xfer)) {
 661                                 /* report completed message */
 662                                 atmel_spi_msg_done(master, as, msg, 0,
 663                                                 xfer->cs_change);
 664                         } else {
 665                                 if (xfer->cs_change) {
 666                                         cs_deactivate(as, msg->spi);
 667                                         udelay(1);
 668                                         cs_activate(as, msg->spi);
 669                                 }
 670
 671                                 /*
 672                                  * Not done yet. Submit the next transfer.
 673                                  *
 674                                  * FIXME handle protocol options for xfer
 675                                  */
 676                                 atmel_spi_next_xfer(master, msg);
 677                         }
 678                 } else {
 679                         /*
 680                          * Keep going, we still have data to send in
 681                          * the current transfer.
 682                          */
 683                         atmel_spi_next_xfer(master, msg);
 684                 }
 685         }
 686
 687         spin_unlock(&as->lock);
 688
 689         return ret;
 690 }
 691
 692 static int atmel_spi_setup(struct spi_device *spi)
 693 {
 694         struct atmel_spi        *as;
 695         struct atmel_spi_device *asd;
 696         u32                     scbr, csr;
 697         unsigned int            bits = spi->bits_per_word;
 698         unsigned long           bus_hz;
 699         unsigned int            npcs_pin;
 700         int                     ret;
 701
 702         as = spi_master_get_devdata(spi->master);
 703
 704         if (as->stopping)
 705                 return -ESHUTDOWN;
 706
 707         if (spi->chip_select > spi->master->num_chipselect) {
 708                 dev_dbg(&spi->dev,
 709                                 "setup: invalid chipselect %u (%u defined)\n",
 710                                 spi->chip_select, spi->master->num_chipselect);
 711                 return -EINVAL;
 712         }
 713
 714         if (bits < 8 || bits > 16) {
 715                 dev_dbg(&spi->dev,
 716                                 "setup: invalid bits_per_word %u (8 to 16)\n",
 717                                 bits);
 718                 return -EINVAL;
 719         }
 720
 721         /* see notes above re chipselect */
 722         if (!atmel_spi_is_v2()
 723                         && spi->chip_select == 0
 724                         && (spi->mode & SPI_CS_HIGH)) {
 725                 dev_dbg(&spi->dev, "setup: can't be active-high\n");
 726                 return -EINVAL;
 727         }
 728
 729         /* v1 chips start out at half the peripheral bus speed. */
 730         bus_hz = clk_get_rate(as->clk);
 731         if (!atmel_spi_is_v2())
 732                 bus_hz /= 2;
 733
 734         if (spi->max_speed_hz) {
 735                 /*
 736                  * Calculate the lowest divider that satisfies the
 737                  * constraint, assuming div32/fdiv/mbz == 0.
 738                  */
 739                 scbr = DIV_ROUND_UP(bus_hz, spi->max_speed_hz);
 740
 741                 /*
 742                  * If the resulting divider doesn't fit into the
 743                  * register bitfield, we can't satisfy the constraint.
 744                  */
 745                 if (scbr >= (1 << SPI_SCBR_SIZE)) {
 746                         dev_dbg(&spi->dev,
 747                                 "setup: %d Hz too slow, scbr %u; min %ld Hz\n",
 748                                 spi->max_speed_hz, scbr, bus_hz/255);
 749                         return -EINVAL;
 750                 }
 751         } else
 752                 /* speed zero means "as slow as possible" */
 753                 scbr = 0xff;
 754
 755         csr = SPI_BF(SCBR, scbr) | SPI_BF(BITS, bits - 8);
 756         if (spi->mode & SPI_CPOL)
 757                 csr |= SPI_BIT(CPOL);
 758         if (!(spi->mode & SPI_CPHA))
 759                 csr |= SPI_BIT(NCPHA);
 760
 761         /* DLYBS is mostly irrelevant since we manage chipselect using GPIOs.
 762          *
 763          * DLYBCT would add delays between words, slowing down transfers.
 764          * It could potentially be useful to cope with DMA bottlenecks, but
 765          * in those cases it's probably best to just use a lower bitrate.
 766          */
 767         csr |= SPI_BF(DLYBS, 0);
 768         csr |= SPI_BF(DLYBCT, 0);
 769
 770         /* chipselect must have been muxed as GPIO (e.g. in board setup) */
 771         npcs_pin = (unsigned int)spi->controller_data;
 772
 773         if (gpio_is_valid(spi->cs_gpio))
 774                 npcs_pin = spi->cs_gpio;
 775
 776         asd = spi->controller_state;
 777         if (!asd) {
 778                 asd = kzalloc(sizeof(struct atmel_spi_device), GFP_KERNEL);
 779                 if (!asd)
 780                         return -ENOMEM;
 781
 782                 ret = gpio_request(npcs_pin, dev_name(&spi->dev));
 783                 if (ret) {
 784                         kfree(asd);
 785                         return ret;
 786                 }
 787
 788                 asd->npcs_pin = npcs_pin;
 789                 spi->controller_state = asd;
 790                 gpio_direction_output(npcs_pin, !(spi->mode & SPI_CS_HIGH));
 791         } else {
 792                 unsigned long           flags;
 793
 794                 spin_lock_irqsave(&as->lock, flags);
 795                 if (as->stay == spi)
 796                         as->stay = NULL;
 797                 cs_deactivate(as, spi);
 798                 spin_unlock_irqrestore(&as->lock, flags);
 799         }
 800
 801         asd->csr = csr;
 802
 803         dev_dbg(&spi->dev,
 804                 "setup: %lu Hz bpw %u mode 0x%x -> csr%d %08x\n",
 805                 bus_hz / scbr, bits, spi->mode, spi->chip_select, csr);
 806
 807         if (!atmel_spi_is_v2())
 808                 spi_writel(as, CSR0 + 4 * spi->chip_select, csr);
 809
 810         return 0;
 811 }
 812
 813 static int atmel_spi_transfer(struct spi_device *spi, struct spi_message *msg)
 814 {
 815         struct atmel_spi        *as;
 816         struct spi_transfer     *xfer;
 817         unsigned long           flags;
 818         struct device           *controller = spi->master->dev.parent;
 819         u8                      bits;
 820         struct atmel_spi_device *asd;
 821
 822         as = spi_master_get_devdata(spi->master);
 823
 824         dev_dbg(controller, "new message %p submitted for %s\n",
 825                         msg, dev_name(&spi->dev));
 826
 827         if (unlikely(list_empty(&msg->transfers)))
 828                 return -EINVAL;
 829
 830         if (as->stopping)
 831                 return -ESHUTDOWN;
 832
 833         list_for_each_entry(xfer, &msg->transfers, transfer_list) {
 834                 if (!(xfer->tx_buf || xfer->rx_buf) && xfer->len) {
 835                         dev_dbg(&spi->dev, "missing rx or tx buf\n");
 836                         return -EINVAL;
 837                 }
 838
 839                 if (xfer->bits_per_word) {
 840                         asd = spi->controller_state;
 841                         bits = (asd->csr >> 4) & 0xf;
 842                         if (bits != xfer->bits_per_word - 8) {
 843                                 dev_dbg(&spi->dev, "you can't yet change "
 844                                          "bits_per_word in transfers\n");
 845                                 return -ENOPROTOOPT;
 846                         }
 847                 }
 848
 849                 /* FIXME implement these protocol options!! */
 850                 if (xfer->speed_hz < spi->max_speed_hz) {
 851                         dev_dbg(&spi->dev, "can't change speed in transfer\n");
 852                         return -ENOPROTOOPT;
 853                 }
 854
 855                 /*
 856                  * DMA map early, for performance (empties dcache ASAP) and
 857                  * better fault reporting.  This is a DMA-only driver.
 858                  *
 859                  * NOTE that if dma_unmap_single() ever starts to do work on
 860                  * platforms supported by this driver, we would need to clean
 861                  * up mappings for previously-mapped transfers.
 862                  */
 863                 if (!msg->is_dma_mapped) {
 864                         if (atmel_spi_dma_map_xfer(as, xfer) < 0)
 865                                 return -ENOMEM;
 866                 }
 867         }
 868
 869 #ifdef VERBOSE
 870         list_for_each_entry(xfer, &msg->transfers, transfer_list) {
 871                 dev_dbg(controller,
 872                         "  xfer %p: len %u tx %p/%08x rx %p/%08x\n",
 873                         xfer, xfer->len,
 874                         xfer->tx_buf, xfer->tx_dma,
 875                         xfer->rx_buf, xfer->rx_dma);
 876         }
 877 #endif
 878
 879         msg->status = -EINPROGRESS;
 880         msg->actual_length = 0;
 881
 882         spin_lock_irqsave(&as->lock, flags);
 883         list_add_tail(&msg->queue, &as->queue);
 884         if (!as->current_transfer)
 885                 atmel_spi_next_message(spi->master);
 886         spin_unlock_irqrestore(&as->lock, flags);
 887
 888         return 0;
 889 }
 890
 891 static void atmel_spi_cleanup(struct spi_device *spi)
 892 {
 893         struct atmel_spi        *as = spi_master_get_devdata(spi->master);
 894         struct atmel_spi_device *asd = spi->controller_state;
 895         unsigned                gpio = (unsigned) spi->controller_data;
 896         unsigned long           flags;
 897
 898         if (!asd)
 899                 return;
 900
 901         spin_lock_irqsave(&as->lock, flags);
 902         if (as->stay == spi) {
 903                 as->stay = NULL;
 904                 cs_deactivate(as, spi);
 905         }
 906         spin_unlock_irqrestore(&as->lock, flags);
 907
 908         spi->controller_state = NULL;
 909         gpio_free(gpio);
 910         kfree(asd);
 911 }
 912
 913 /*-------------------------------------------------------------------------*/
 914
 915 static int atmel_spi_probe(struct platform_device *pdev)
 916 {
 917         struct resource         *regs;
 918         int                     irq;
 919         struct clk              *clk;
 920         int                     ret;
 921         struct spi_master       *master;
 922         struct atmel_spi        *as;
 923
 924         regs = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 925         if (!regs)
 926                 return -ENXIO;
 927
 928         irq = platform_get_irq(pdev, 0);
 929         if (irq < 0)
 930                 return irq;
 931
 932         clk = clk_get(&pdev->dev, "spi_clk");
 933         if (IS_ERR(clk))
 934                 return PTR_ERR(clk);
 935
 936         /* setup spi core then atmel-specific driver state */
 937         ret = -ENOMEM;
 938         master = spi_alloc_master(&pdev->dev, sizeof *as);
 939         if (!master)
 940                 goto out_free;
 941
 942         /* the spi->mode bits understood by this driver: */
 943         master->mode_bits = SPI_CPOL | SPI_CPHA | SPI_CS_HIGH;
 944
 945         master->dev.of_node = pdev->dev.of_node;
 946         master->bus_num = pdev->id;
 947         master->num_chipselect = master->dev.of_node ? 0 : 4;
 948         master->setup = atmel_spi_setup;
 949         master->transfer = atmel_spi_transfer;
 950         master->cleanup = atmel_spi_cleanup;
 951         platform_set_drvdata(pdev, master);
 952
 953         as = spi_master_get_devdata(master);
 954
 955         /*
 956          * Scratch buffer is used for throwaway rx and tx data.
 957          * It's coherent to minimize dcache pollution.
 958          */
 959         as->buffer = dma_alloc_coherent(&pdev->dev, BUFFER_SIZE,
 960                                         &as->buffer_dma, GFP_KERNEL);
 961         if (!as->buffer)
 962                 goto out_free;
 963
 964         spin_lock_init(&as->lock);
 965         INIT_LIST_HEAD(&as->queue);
 966         as->pdev = pdev;
 967         as->regs = ioremap(regs->start, resource_size(regs));
 968         if (!as->regs)
 969                 goto out_free_buffer;
 970         as->irq = irq;
 971         as->clk = clk;
 972
 973         ret = request_irq(irq, atmel_spi_interrupt, 0,
 974                         dev_name(&pdev->dev), master);
 975         if (ret)
 976                 goto out_unmap_regs;
 977
 978         /* Initialize the hardware */
 979         clk_enable(clk);
 980         spi_writel(as, CR, SPI_BIT(SWRST));
 981         spi_writel(as, CR, SPI_BIT(SWRST)); /* AT91SAM9263 Rev B workaround */
 982         spi_writel(as, MR, SPI_BIT(MSTR) | SPI_BIT(MODFDIS));
 983         spi_writel(as, PTCR, SPI_BIT(RXTDIS) | SPI_BIT(TXTDIS));
 984         spi_writel(as, CR, SPI_BIT(SPIEN));
 985
 986         /* go! */
 987         dev_info(&pdev->dev, "Atmel SPI Controller at 0x%08lx (irq %d)\n",
 988                         (unsigned long)regs->start, irq);
 989
 990         ret = spi_register_master(master);
 991         if (ret)
 992                 goto out_reset_hw;
 993
 994         return 0;
 995
 996 out_reset_hw:
 997         spi_writel(as, CR, SPI_BIT(SWRST));
 998         spi_writel(as, CR, SPI_BIT(SWRST)); /* AT91SAM9263 Rev B workaround */
 999         clk_disable(clk);
1000         free_irq(irq, master);
1001 out_unmap_regs:
1002         iounmap(as->regs);
1003 out_free_buffer:
1004         dma_free_coherent(&pdev->dev, BUFFER_SIZE, as->buffer,
1005                         as->buffer_dma);
1006 out_free:
1007         clk_put(clk);
1008         spi_master_put(master);
1009         return ret;
1010 }
1011
1012 static int atmel_spi_remove(struct platform_device *pdev)
1013 {
1014         struct spi_master       *master = platform_get_drvdata(pdev);
1015         struct atmel_spi        *as = spi_master_get_devdata(master);
1016         struct spi_message      *msg;
1017
1018         /* reset the hardware and block queue progress */
1019         spin_lock_irq(&as->lock);
1020         as->stopping = 1;
1021         spi_writel(as, CR, SPI_BIT(SWRST));
1022         spi_writel(as, CR, SPI_BIT(SWRST)); /* AT91SAM9263 Rev B workaround */
1023         spi_readl(as, SR);
1024         spin_unlock_irq(&as->lock);
1025
1026         /* Terminate remaining queued transfers */
1027         list_for_each_entry(msg, &as->queue, queue) {
1028                 /* REVISIT unmapping the dma is a NOP on ARM and AVR32
1029                  * but we shouldn't depend on that...
1030                  */
1031                 msg->status = -ESHUTDOWN;
1032                 msg->complete(msg->context);
1033         }
1034
1035         dma_free_coherent(&pdev->dev, BUFFER_SIZE, as->buffer,
1036                         as->buffer_dma);
1037
1038         clk_disable(as->clk);
1039         clk_put(as->clk);
1040         free_irq(as->irq, master);
1041         iounmap(as->regs);
1042
1043         spi_unregister_master(master);
1044
1045         return 0;
1046 }
1047
1048 #ifdef  CONFIG_PM
1049
1050 static int atmel_spi_suspend(struct platform_device *pdev, pm_message_t mesg)
1051 {
1052         struct spi_master       *master = platform_get_drvdata(pdev);
1053         struct atmel_spi        *as = spi_master_get_devdata(master);
1054
1055         clk_disable(as->clk);
1056         return 0;
1057 }
1058
1059 static int atmel_spi_resume(struct platform_device *pdev)
1060 {
1061         struct spi_master       *master = platform_get_drvdata(pdev);
1062         struct atmel_spi        *as = spi_master_get_devdata(master);
1063
1064         clk_enable(as->clk);
1065         return 0;
1066 }
1067
1068 #else
1069 #define atmel_spi_suspend       NULL
1070 #define atmel_spi_resume        NULL
1071 #endif
1072
1073 #if defined(CONFIG_OF)
1074 static const struct of_device_id atmel_spi_dt_ids[] = {
1075         { .compatible = "atmel,at91rm9200-spi" },
1076         { /* sentinel */ }
1077 };
1078
1079 MODULE_DEVICE_TABLE(of, atmel_spi_dt_ids);
1080 #endif
1081
1082 static struct platform_driver atmel_spi_driver = {
1083         .driver         = {
1084                 .name   = "atmel_spi",
1085                 .owner  = THIS_MODULE,
1086                 .of_match_table = of_match_ptr(atmel_spi_dt_ids),
1087         },
1088         .suspend        = atmel_spi_suspend,
1089         .resume         = atmel_spi_resume,
1090         .probe          = atmel_spi_probe,
1091         .remove         = atmel_spi_remove,
1092 };
1093 module_platform_driver(atmel_spi_driver);
1094
1095 MODULE_DESCRIPTION("Atmel AT32/AT91 SPI Controller driver");
1096 MODULE_AUTHOR("Haavard Skinnemoen (Atmel)");
1097 MODULE_LICENSE("GPL");
1098 MODULE_ALIAS("platform:atmel_spi");