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