drivers/spi/mpc52xx_spi.c

   1 /*
   2  * MPC52xx SPI bus driver.
   3  *
   4  * Copyright (C) 2008 Secret Lab Technologies Ltd.
   5  *
   6  * This file is released under the GPLv2
   7  *
   8  * This is the driver for the MPC5200's dedicated SPI controller.
   9  *
  10  * Note: this driver does not support the MPC5200 PSC in SPI mode.  For
  11  * that driver see drivers/spi/mpc52xx_psc_spi.c
  12  */
  13
  14 #include <linux/module.h>
  15 #include <linux/init.h>
  16 #include <linux/errno.h>
  17 #include <linux/of_platform.h>
  18 #include <linux/interrupt.h>
  19 #include <linux/delay.h>
  20 #include <linux/spi/spi.h>
  21 #include <linux/of_spi.h>
  22 #include <linux/io.h>
  23 #include <linux/of_gpio.h>
  24 #include <linux/slab.h>
  25 #include <asm/time.h>
  26 #include <asm/mpc52xx.h>
  27
  28 MODULE_AUTHOR("Grant Likely <grant.likely@secretlab.ca>");
  29 MODULE_DESCRIPTION("MPC52xx SPI (non-PSC) Driver");
  30 MODULE_LICENSE("GPL");
  31
  32 /* Register offsets */
  33 #define SPI_CTRL1       0x00
  34 #define SPI_CTRL1_SPIE          (1 << 7)
  35 #define SPI_CTRL1_SPE           (1 << 6)
  36 #define SPI_CTRL1_MSTR          (1 << 4)
  37 #define SPI_CTRL1_CPOL          (1 << 3)
  38 #define SPI_CTRL1_CPHA          (1 << 2)
  39 #define SPI_CTRL1_SSOE          (1 << 1)
  40 #define SPI_CTRL1_LSBFE         (1 << 0)
  41
  42 #define SPI_CTRL2       0x01
  43 #define SPI_BRR         0x04
  44
  45 #define SPI_STATUS      0x05
  46 #define SPI_STATUS_SPIF         (1 << 7)
  47 #define SPI_STATUS_WCOL         (1 << 6)
  48 #define SPI_STATUS_MODF         (1 << 4)
  49
  50 #define SPI_DATA        0x09
  51 #define SPI_PORTDATA    0x0d
  52 #define SPI_DATADIR     0x10
  53
  54 /* FSM state return values */
  55 #define FSM_STOP        0       /* Nothing more for the state machine to */
  56                                 /* do.  If something interesting happens */
  57                                 /* then an IRQ will be received */
  58 #define FSM_POLL        1       /* need to poll for completion, an IRQ is */
  59                                 /* not expected */
  60 #define FSM_CONTINUE    2       /* Keep iterating the state machine */
  61
  62 /* Driver internal data */
  63 struct mpc52xx_spi {
  64         struct spi_master *master;
  65         void __iomem *regs;
  66         int irq0;       /* MODF irq */
  67         int irq1;       /* SPIF irq */
  68         unsigned int ipb_freq;
  69
  70         /* Statistics; not used now, but will be reintroduced for debugfs */
  71         int msg_count;
  72         int wcol_count;
  73         int wcol_ticks;
  74         u32 wcol_tx_timestamp;
  75         int modf_count;
  76         int byte_count;
  77
  78         struct list_head queue;         /* queue of pending messages */
  79         spinlock_t lock;
  80         struct work_struct work;
  81
  82         /* Details of current transfer (length, and buffer pointers) */
  83         struct spi_message *message;    /* current message */
  84         struct spi_transfer *transfer;  /* current transfer */
  85         int (*state)(int irq, struct mpc52xx_spi *ms, u8 status, u8 data);
  86         int len;
  87         int timestamp;
  88         u8 *rx_buf;
  89         const u8 *tx_buf;
  90         int cs_change;
  91         int gpio_cs_count;
  92         unsigned int *gpio_cs;
  93 };
  94
  95 /*
  96  * CS control function
  97  */
  98 static void mpc52xx_spi_chipsel(struct mpc52xx_spi *ms, int value)
  99 {
 100         int cs;
 101
 102         if (ms->gpio_cs_count > 0) {
 103                 cs = ms->message->spi->chip_select;
 104                 gpio_set_value(ms->gpio_cs[cs], value ? 0 : 1);
 105         } else
 106                 out_8(ms->regs + SPI_PORTDATA, value ? 0 : 0x08);
 107 }
 108
 109 /*
 110  * Start a new transfer.  This is called both by the idle state
 111  * for the first transfer in a message, and by the wait state when the
 112  * previous transfer in a message is complete.
 113  */
 114 static void mpc52xx_spi_start_transfer(struct mpc52xx_spi *ms)
 115 {
 116         ms->rx_buf = ms->transfer->rx_buf;
 117         ms->tx_buf = ms->transfer->tx_buf;
 118         ms->len = ms->transfer->len;
 119
 120         /* Activate the chip select */
 121         if (ms->cs_change)
 122                 mpc52xx_spi_chipsel(ms, 1);
 123         ms->cs_change = ms->transfer->cs_change;
 124
 125         /* Write out the first byte */
 126         ms->wcol_tx_timestamp = get_tbl();
 127         if (ms->tx_buf)
 128                 out_8(ms->regs + SPI_DATA, *ms->tx_buf++);
 129         else
 130                 out_8(ms->regs + SPI_DATA, 0);
 131 }
 132
 133 /* Forward declaration of state handlers */
 134 static int mpc52xx_spi_fsmstate_transfer(int irq, struct mpc52xx_spi *ms,
 135                                          u8 status, u8 data);
 136 static int mpc52xx_spi_fsmstate_wait(int irq, struct mpc52xx_spi *ms,
 137                                      u8 status, u8 data);
 138
 139 /*
 140  * IDLE state
 141  *
 142  * No transfers are in progress; if another transfer is pending then retrieve
 143  * it and kick it off.  Otherwise, stop processing the state machine
 144  */
 145 static int
 146 mpc52xx_spi_fsmstate_idle(int irq, struct mpc52xx_spi *ms, u8 status, u8 data)
 147 {
 148         struct spi_device *spi;
 149         int spr, sppr;
 150         u8 ctrl1;
 151
 152         if (status && (irq != NO_IRQ))
 153                 dev_err(&ms->master->dev, "spurious irq, status=0x%.2x\n",
 154                         status);
 155
 156         /* Check if there is another transfer waiting. */
 157         if (list_empty(&ms->queue))
 158                 return FSM_STOP;
 159
 160         /* get the head of the queue */
 161         ms->message = list_first_entry(&ms->queue, struct spi_message, queue);
 162         list_del_init(&ms->message->queue);
 163
 164         /* Setup the controller parameters */
 165         ctrl1 = SPI_CTRL1_SPIE | SPI_CTRL1_SPE | SPI_CTRL1_MSTR;
 166         spi = ms->message->spi;
 167         if (spi->mode & SPI_CPHA)
 168                 ctrl1 |= SPI_CTRL1_CPHA;
 169         if (spi->mode & SPI_CPOL)
 170                 ctrl1 |= SPI_CTRL1_CPOL;
 171         if (spi->mode & SPI_LSB_FIRST)
 172                 ctrl1 |= SPI_CTRL1_LSBFE;
 173         out_8(ms->regs + SPI_CTRL1, ctrl1);
 174
 175         /* Setup the controller speed */
 176         /* minimum divider is '2'.  Also, add '1' to force rounding the
 177          * divider up. */
 178         sppr = ((ms->ipb_freq / ms->message->spi->max_speed_hz) + 1) >> 1;
 179         spr = 0;
 180         if (sppr < 1)
 181                 sppr = 1;
 182         while (((sppr - 1) & ~0x7) != 0) {
 183                 sppr = (sppr + 1) >> 1; /* add '1' to force rounding up */
 184                 spr++;
 185         }
 186         sppr--;         /* sppr quantity in register is offset by 1 */
 187         if (spr > 7) {
 188                 /* Don't overrun limits of SPI baudrate register */
 189                 spr = 7;
 190                 sppr = 7;
 191         }
 192         out_8(ms->regs + SPI_BRR, sppr << 4 | spr); /* Set speed */
 193
 194         ms->cs_change = 1;
 195         ms->transfer = container_of(ms->message->transfers.next,
 196                                     struct spi_transfer, transfer_list);
 197
 198         mpc52xx_spi_start_transfer(ms);
 199         ms->state = mpc52xx_spi_fsmstate_transfer;
 200
 201         return FSM_CONTINUE;
 202 }
 203
 204 /*
 205  * TRANSFER state
 206  *
 207  * In the middle of a transfer.  If the SPI core has completed processing
 208  * a byte, then read out the received data and write out the next byte
 209  * (unless this transfer is finished; in which case go on to the wait
 210  * state)
 211  */
 212 static int mpc52xx_spi_fsmstate_transfer(int irq, struct mpc52xx_spi *ms,
 213                                          u8 status, u8 data)
 214 {
 215         if (!status)
 216                 return ms->irq0 ? FSM_STOP : FSM_POLL;
 217
 218         if (status & SPI_STATUS_WCOL) {
 219                 /* The SPI controller is stoopid.  At slower speeds, it may
 220                  * raise the SPIF flag before the state machine is actually
 221                  * finished, which causes a collision (internal to the state
 222                  * machine only).  The manual recommends inserting a delay
 223                  * between receiving the interrupt and sending the next byte,
 224                  * but it can also be worked around simply by retrying the
 225                  * transfer which is what we do here. */
 226                 ms->wcol_count++;
 227                 ms->wcol_ticks += get_tbl() - ms->wcol_tx_timestamp;
 228                 ms->wcol_tx_timestamp = get_tbl();
 229                 data = 0;
 230                 if (ms->tx_buf)
 231                         data = *(ms->tx_buf - 1);
 232                 out_8(ms->regs + SPI_DATA, data); /* try again */
 233                 return FSM_CONTINUE;
 234         } else if (status & SPI_STATUS_MODF) {
 235                 ms->modf_count++;
 236                 dev_err(&ms->master->dev, "mode fault\n");
 237                 mpc52xx_spi_chipsel(ms, 0);
 238                 ms->message->status = -EIO;
 239                 ms->message->complete(ms->message->context);
 240                 ms->state = mpc52xx_spi_fsmstate_idle;
 241                 return FSM_CONTINUE;
 242         }
 243
 244         /* Read data out of the spi device */
 245         ms->byte_count++;
 246         if (ms->rx_buf)
 247                 *ms->rx_buf++ = data;
 248
 249         /* Is the transfer complete? */
 250         ms->len--;
 251         if (ms->len == 0) {
 252                 ms->timestamp = get_tbl();
 253                 ms->timestamp += ms->transfer->delay_usecs * tb_ticks_per_usec;
 254                 ms->state = mpc52xx_spi_fsmstate_wait;
 255                 return FSM_CONTINUE;
 256         }
 257
 258         /* Write out the next byte */
 259         ms->wcol_tx_timestamp = get_tbl();
 260         if (ms->tx_buf)
 261                 out_8(ms->regs + SPI_DATA, *ms->tx_buf++);
 262         else
 263                 out_8(ms->regs + SPI_DATA, 0);
 264
 265         return FSM_CONTINUE;
 266 }
 267
 268 /*
 269  * WAIT state
 270  *
 271  * A transfer has completed; need to wait for the delay period to complete
 272  * before starting the next transfer
 273  */
 274 static int
 275 mpc52xx_spi_fsmstate_wait(int irq, struct mpc52xx_spi *ms, u8 status, u8 data)
 276 {
 277         if (status && irq)
 278                 dev_err(&ms->master->dev, "spurious irq, status=0x%.2x\n",
 279                         status);
 280
 281         if (((int)get_tbl()) - ms->timestamp < 0)
 282                 return FSM_POLL;
 283
 284         ms->message->actual_length += ms->transfer->len;
 285
 286         /* Check if there is another transfer in this message.  If there
 287          * aren't then deactivate CS, notify sender, and drop back to idle
 288          * to start the next message. */
 289         if (ms->transfer->transfer_list.next == &ms->message->transfers) {
 290                 ms->msg_count++;
 291                 mpc52xx_spi_chipsel(ms, 0);
 292                 ms->message->status = 0;
 293                 ms->message->complete(ms->message->context);
 294                 ms->state = mpc52xx_spi_fsmstate_idle;
 295                 return FSM_CONTINUE;
 296         }
 297
 298         /* There is another transfer; kick it off */
 299
 300         if (ms->cs_change)
 301                 mpc52xx_spi_chipsel(ms, 0);
 302
 303         ms->transfer = container_of(ms->transfer->transfer_list.next,
 304                                     struct spi_transfer, transfer_list);
 305         mpc52xx_spi_start_transfer(ms);
 306         ms->state = mpc52xx_spi_fsmstate_transfer;
 307         return FSM_CONTINUE;
 308 }
 309
 310 /**
 311  * mpc52xx_spi_fsm_process - Finite State Machine iteration function
 312  * @irq: irq number that triggered the FSM or 0 for polling
 313  * @ms: pointer to mpc52xx_spi driver data
 314  */
 315 static void mpc52xx_spi_fsm_process(int irq, struct mpc52xx_spi *ms)
 316 {
 317         int rc = FSM_CONTINUE;
 318         u8 status, data;
 319
 320         while (rc == FSM_CONTINUE) {
 321                 /* Interrupt cleared by read of STATUS followed by
 322                  * read of DATA registers */
 323                 status = in_8(ms->regs + SPI_STATUS);
 324                 data = in_8(ms->regs + SPI_DATA);
 325                 rc = ms->state(irq, ms, status, data);
 326         }
 327
 328         if (rc == FSM_POLL)
 329                 schedule_work(&ms->work);
 330 }
 331
 332 /**
 333  * mpc52xx_spi_irq - IRQ handler
 334  */
 335 static irqreturn_t mpc52xx_spi_irq(int irq, void *_ms)
 336 {
 337         struct mpc52xx_spi *ms = _ms;
 338         spin_lock(&ms->lock);
 339         mpc52xx_spi_fsm_process(irq, ms);
 340         spin_unlock(&ms->lock);
 341         return IRQ_HANDLED;
 342 }
 343
 344 /**
 345  * mpc52xx_spi_wq - Workqueue function for polling the state machine
 346  */
 347 static void mpc52xx_spi_wq(struct work_struct *work)
 348 {
 349         struct mpc52xx_spi *ms = container_of(work, struct mpc52xx_spi, work);
 350         unsigned long flags;
 351
 352         spin_lock_irqsave(&ms->lock, flags);
 353         mpc52xx_spi_fsm_process(0, ms);
 354         spin_unlock_irqrestore(&ms->lock, flags);
 355 }
 356
 357 /*
 358  * spi_master ops
 359  */
 360
 361 static int mpc52xx_spi_setup(struct spi_device *spi)
 362 {
 363         if (spi->bits_per_word % 8)
 364                 return -EINVAL;
 365
 366         if (spi->mode & ~(SPI_CPOL | SPI_CPHA | SPI_LSB_FIRST))
 367                 return -EINVAL;
 368
 369         if (spi->chip_select >= spi->master->num_chipselect)
 370                 return -EINVAL;
 371
 372         return 0;
 373 }
 374
 375 static int mpc52xx_spi_transfer(struct spi_device *spi, struct spi_message *m)
 376 {
 377         struct mpc52xx_spi *ms = spi_master_get_devdata(spi->master);
 378         unsigned long flags;
 379
 380         m->actual_length = 0;
 381         m->status = -EINPROGRESS;
 382
 383         spin_lock_irqsave(&ms->lock, flags);
 384         list_add_tail(&m->queue, &ms->queue);
 385         spin_unlock_irqrestore(&ms->lock, flags);
 386         schedule_work(&ms->work);
 387
 388         return 0;
 389 }
 390
 391 /*
 392  * OF Platform Bus Binding
 393  */
 394 static int __devinit mpc52xx_spi_probe(struct of_device *op,
 395                                        const struct of_device_id *match)
 396 {
 397         struct spi_master *master;
 398         struct mpc52xx_spi *ms;
 399         void __iomem *regs;
 400         u8 ctrl1;
 401         int rc, i = 0;
 402         int gpio_cs;
 403
 404         /* MMIO registers */
 405         dev_dbg(&op->dev, "probing mpc5200 SPI device\n");
 406         regs = of_iomap(op->dev.of_node, 0);
 407         if (!regs)
 408                 return -ENODEV;
 409
 410         /* initialize the device */
 411         ctrl1 = SPI_CTRL1_SPIE | SPI_CTRL1_SPE | SPI_CTRL1_MSTR;
 412         out_8(regs + SPI_CTRL1, ctrl1);
 413         out_8(regs + SPI_CTRL2, 0x0);
 414         out_8(regs + SPI_DATADIR, 0xe); /* Set output pins */
 415         out_8(regs + SPI_PORTDATA, 0x8);        /* Deassert /SS signal */
 416
 417         /* Clear the status register and re-read it to check for a MODF
 418          * failure.  This driver cannot currently handle multiple masters
 419          * on the SPI bus.  This fault will also occur if the SPI signals
 420          * are not connected to any pins (port_config setting) */
 421         in_8(regs + SPI_STATUS);
 422         out_8(regs + SPI_CTRL1, ctrl1);
 423
 424         in_8(regs + SPI_DATA);
 425         if (in_8(regs + SPI_STATUS) & SPI_STATUS_MODF) {
 426                 dev_err(&op->dev, "mode fault; is port_config correct?\n");
 427                 rc = -EIO;
 428                 goto err_init;
 429         }
 430
 431         dev_dbg(&op->dev, "allocating spi_master struct\n");
 432         master = spi_alloc_master(&op->dev, sizeof *ms);
 433         if (!master) {
 434                 rc = -ENOMEM;
 435                 goto err_alloc;
 436         }
 437
 438         master->bus_num = -1;
 439         master->setup = mpc52xx_spi_setup;
 440         master->transfer = mpc52xx_spi_transfer;
 441         master->mode_bits = SPI_CPOL | SPI_CPHA | SPI_LSB_FIRST;
 442
 443         dev_set_drvdata(&op->dev, master);
 444
 445         ms = spi_master_get_devdata(master);
 446         ms->master = master;
 447         ms->regs = regs;
 448         ms->irq0 = irq_of_parse_and_map(op->dev.of_node, 0);
 449         ms->irq1 = irq_of_parse_and_map(op->dev.of_node, 1);
 450         ms->state = mpc52xx_spi_fsmstate_idle;
 451         ms->ipb_freq = mpc5xxx_get_bus_frequency(op->dev.of_node);
 452         ms->gpio_cs_count = of_gpio_count(op->dev.of_node);
 453         if (ms->gpio_cs_count > 0) {
 454                 master->num_chipselect = ms->gpio_cs_count;
 455                 ms->gpio_cs = kmalloc(ms->gpio_cs_count * sizeof(unsigned int),
 456                                 GFP_KERNEL);
 457                 if (!ms->gpio_cs) {
 458                         rc = -ENOMEM;
 459                         goto err_alloc;
 460                 }
 461
 462                 for (i = 0; i < ms->gpio_cs_count; i++) {
 463                         gpio_cs = of_get_gpio(op->dev.of_node, i);
 464                         if (gpio_cs < 0) {
 465                                 dev_err(&op->dev,
 466                                         "could not parse the gpio field "
 467                                         "in oftree\n");
 468                                 rc = -ENODEV;
 469                                 goto err_gpio;
 470                         }
 471
 472                         rc = gpio_request(gpio_cs, dev_name(&op->dev));
 473                         if (rc) {
 474                                 dev_err(&op->dev,
 475                                         "can't request spi cs gpio #%d "
 476                                         "on gpio line %d\n", i, gpio_cs);
 477                                 goto err_gpio;
 478                         }
 479
 480                         gpio_direction_output(gpio_cs, 1);
 481                         ms->gpio_cs[i] = gpio_cs;
 482                 }
 483         } else {
 484                 master->num_chipselect = 1;
 485         }
 486
 487         spin_lock_init(&ms->lock);
 488         INIT_LIST_HEAD(&ms->queue);
 489         INIT_WORK(&ms->work, mpc52xx_spi_wq);
 490
 491         /* Decide if interrupts can be used */
 492         if (ms->irq0 && ms->irq1) {
 493                 rc = request_irq(ms->irq0, mpc52xx_spi_irq, 0,
 494                                   "mpc5200-spi-modf", ms);
 495                 rc |= request_irq(ms->irq1, mpc52xx_spi_irq, 0,
 496                                   "mpc5200-spi-spif", ms);
 497                 if (rc) {
 498                         free_irq(ms->irq0, ms);
 499                         free_irq(ms->irq1, ms);
 500                         ms->irq0 = ms->irq1 = 0;
 501                 }
 502         } else {
 503                 /* operate in polled mode */
 504                 ms->irq0 = ms->irq1 = 0;
 505         }
 506
 507         if (!ms->irq0)
 508                 dev_info(&op->dev, "using polled mode\n");
 509
 510         dev_dbg(&op->dev, "registering spi_master struct\n");
 511         rc = spi_register_master(master);
 512         if (rc)
 513                 goto err_register;
 514
 515         of_register_spi_devices(master, op->dev.of_node);
 516         dev_info(&ms->master->dev, "registered MPC5200 SPI bus\n");
 517
 518         return rc;
 519
 520  err_register:
 521         dev_err(&ms->master->dev, "initialization failed\n");
 522         spi_master_put(master);
 523  err_gpio:
 524         while (i-- > 0)
 525                 gpio_free(ms->gpio_cs[i]);
 526
 527         kfree(ms->gpio_cs);
 528  err_alloc:
 529  err_init:
 530         iounmap(regs);
 531         return rc;
 532 }
 533
 534 static int __devexit mpc52xx_spi_remove(struct of_device *op)
 535 {
 536         struct spi_master *master = dev_get_drvdata(&op->dev);
 537         struct mpc52xx_spi *ms = spi_master_get_devdata(master);
 538         int i;
 539
 540         free_irq(ms->irq0, ms);
 541         free_irq(ms->irq1, ms);
 542
 543         for (i = 0; i < ms->gpio_cs_count; i++)
 544                 gpio_free(ms->gpio_cs[i]);
 545
 546         kfree(ms->gpio_cs);
 547         spi_unregister_master(master);
 548         spi_master_put(master);
 549         iounmap(ms->regs);
 550
 551         return 0;
 552 }
 553
 554 static const struct of_device_id mpc52xx_spi_match[] __devinitconst = {
 555         { .compatible = "fsl,mpc5200-spi", },
 556         {}
 557 };
 558 MODULE_DEVICE_TABLE(of, mpc52xx_spi_match);
 559
 560 static struct of_platform_driver mpc52xx_spi_of_driver = {
 561         .driver = {
 562                 .name = "mpc52xx-spi",
 563                 .owner = THIS_MODULE,
 564                 .of_match_table = mpc52xx_spi_match,
 565         },
 566         .probe = mpc52xx_spi_probe,
 567         .remove = __exit_p(mpc52xx_spi_remove),
 568 };
 569
 570 static int __init mpc52xx_spi_init(void)
 571 {
 572         return of_register_platform_driver(&mpc52xx_spi_of_driver);
 573 }
 574 module_init(mpc52xx_spi_init);
 575
 576 static void __exit mpc52xx_spi_exit(void)
 577 {
 578         of_unregister_platform_driver(&mpc52xx_spi_of_driver);
 579 }
 580 module_exit(mpc52xx_spi_exit);
 581