drivers/spi/spi-ppc4xx.c

   1 /*
   2  * SPI_PPC4XX SPI controller driver.
   3  *
   4  * Copyright (C) 2007 Gary Jennejohn <garyj@denx.de>
   5  * Copyright 2008 Stefan Roese <sr@denx.de>, DENX Software Engineering
   6  * Copyright 2009 Harris Corporation, Steven A. Falco <sfalco@harris.com>
   7  *
   8  * Based in part on drivers/spi/spi_s3c24xx.c
   9  *
  10  * Copyright (c) 2006 Ben Dooks
  11  * Copyright (c) 2006 Simtec Electronics
  12  *      Ben Dooks <ben@simtec.co.uk>
  13  *
  14  * This program is free software; you can redistribute  it and/or modify it
  15  * under the terms of the GNU General Public License version 2 as published
  16  * by the Free Software Foundation.
  17  */
  18
  19 /*
  20  * The PPC4xx SPI controller has no FIFO so each sent/received byte will
  21  * generate an interrupt to the CPU. This can cause high CPU utilization.
  22  * This driver allows platforms to reduce the interrupt load on the CPU
  23  * during SPI transfers by setting max_speed_hz via the device tree.
  24  */
  25
  26 #include <linux/module.h>
  27 #include <linux/init.h>
  28 #include <linux/sched.h>
  29 #include <linux/slab.h>
  30 #include <linux/errno.h>
  31 #include <linux/wait.h>
  32 #include <linux/of_platform.h>
  33 #include <linux/of_gpio.h>
  34 #include <linux/interrupt.h>
  35 #include <linux/delay.h>
  36
  37 #include <linux/gpio.h>
  38 #include <linux/spi/spi.h>
  39 #include <linux/spi/spi_bitbang.h>
  40
  41 #include <asm/io.h>
  42 #include <asm/dcr.h>
  43 #include <asm/dcr-regs.h>
  44
  45 /* bits in mode register - bit 0 is MSb */
  46
  47 /*
  48  * SPI_PPC4XX_MODE_SCP = 0 means "data latched on trailing edge of clock"
  49  * SPI_PPC4XX_MODE_SCP = 1 means "data latched on leading edge of clock"
  50  * Note: This is the inverse of CPHA.
  51  */
  52 #define SPI_PPC4XX_MODE_SCP     (0x80 >> 3)
  53
  54 /* SPI_PPC4XX_MODE_SPE = 1 means "port enabled" */
  55 #define SPI_PPC4XX_MODE_SPE     (0x80 >> 4)
  56
  57 /*
  58  * SPI_PPC4XX_MODE_RD = 0 means "MSB first" - this is the normal mode
  59  * SPI_PPC4XX_MODE_RD = 1 means "LSB first" - this is bit-reversed mode
  60  * Note: This is identical to SPI_LSB_FIRST.
  61  */
  62 #define SPI_PPC4XX_MODE_RD      (0x80 >> 5)
  63
  64 /*
  65  * SPI_PPC4XX_MODE_CI = 0 means "clock idles low"
  66  * SPI_PPC4XX_MODE_CI = 1 means "clock idles high"
  67  * Note: This is identical to CPOL.
  68  */
  69 #define SPI_PPC4XX_MODE_CI      (0x80 >> 6)
  70
  71 /*
  72  * SPI_PPC4XX_MODE_IL = 0 means "loopback disable"
  73  * SPI_PPC4XX_MODE_IL = 1 means "loopback enable"
  74  */
  75 #define SPI_PPC4XX_MODE_IL      (0x80 >> 7)
  76
  77 /* bits in control register */
  78 /* starts a transfer when set */
  79 #define SPI_PPC4XX_CR_STR       (0x80 >> 7)
  80
  81 /* bits in status register */
  82 /* port is busy with a transfer */
  83 #define SPI_PPC4XX_SR_BSY       (0x80 >> 6)
  84 /* RxD ready */
  85 #define SPI_PPC4XX_SR_RBR       (0x80 >> 7)
  86
  87 /* clock settings (SCP and CI) for various SPI modes */
  88 #define SPI_CLK_MODE0   (SPI_PPC4XX_MODE_SCP | 0)
  89 #define SPI_CLK_MODE1   (0 | 0)
  90 #define SPI_CLK_MODE2   (SPI_PPC4XX_MODE_SCP | SPI_PPC4XX_MODE_CI)
  91 #define SPI_CLK_MODE3   (0 | SPI_PPC4XX_MODE_CI)
  92
  93 #define DRIVER_NAME     "spi_ppc4xx_of"
  94
  95 struct spi_ppc4xx_regs {
  96         u8 mode;
  97         u8 rxd;
  98         u8 txd;
  99         u8 cr;
 100         u8 sr;
 101         u8 dummy;
 102         /*
 103          * Clock divisor modulus register
 104          * This uses the following formula:
 105          *    SCPClkOut = OPBCLK/(4(CDM + 1))
 106          * or
 107          *    CDM = (OPBCLK/4*SCPClkOut) - 1
 108          * bit 0 is the MSb!
 109          */
 110         u8 cdm;
 111 };
 112
 113 /* SPI Controller driver's private data. */
 114 struct ppc4xx_spi {
 115         /* bitbang has to be first */
 116         struct spi_bitbang bitbang;
 117         struct completion done;
 118
 119         u64 mapbase;
 120         u64 mapsize;
 121         int irqnum;
 122         /* need this to set the SPI clock */
 123         unsigned int opb_freq;
 124
 125         /* for transfers */
 126         int len;
 127         int count;
 128         /* data buffers */
 129         const unsigned char *tx;
 130         unsigned char *rx;
 131
 132         int *gpios;
 133
 134         struct spi_ppc4xx_regs __iomem *regs; /* pointer to the registers */
 135         struct spi_master *master;
 136         struct device *dev;
 137 };
 138
 139 /* need this so we can set the clock in the chipselect routine */
 140 struct spi_ppc4xx_cs {
 141         u8 mode;
 142 };
 143
 144 static int spi_ppc4xx_txrx(struct spi_device *spi, struct spi_transfer *t)
 145 {
 146         struct ppc4xx_spi *hw;
 147         u8 data;
 148
 149         dev_dbg(&spi->dev, "txrx: tx %p, rx %p, len %d\n",
 150                 t->tx_buf, t->rx_buf, t->len);
 151
 152         hw = spi_master_get_devdata(spi->master);
 153
 154         hw->tx = t->tx_buf;
 155         hw->rx = t->rx_buf;
 156         hw->len = t->len;
 157         hw->count = 0;
 158
 159         /* send the first byte */
 160         data = hw->tx ? hw->tx[0] : 0;
 161         out_8(&hw->regs->txd, data);
 162         out_8(&hw->regs->cr, SPI_PPC4XX_CR_STR);
 163         wait_for_completion(&hw->done);
 164
 165         return hw->count;
 166 }
 167
 168 static int spi_ppc4xx_setupxfer(struct spi_device *spi, struct spi_transfer *t)
 169 {
 170         struct ppc4xx_spi *hw = spi_master_get_devdata(spi->master);
 171         struct spi_ppc4xx_cs *cs = spi->controller_state;
 172         int scr;
 173         u8 cdm = 0;
 174         u32 speed;
 175         u8 bits_per_word;
 176
 177         /* Start with the generic configuration for this device. */
 178         bits_per_word = spi->bits_per_word;
 179         speed = spi->max_speed_hz;
 180
 181         /*
 182          * Modify the configuration if the transfer overrides it.  Do not allow
 183          * the transfer to overwrite the generic configuration with zeros.
 184          */
 185         if (t) {
 186                 if (t->bits_per_word)
 187                         bits_per_word = t->bits_per_word;
 188
 189                 if (t->speed_hz)
 190                         speed = min(t->speed_hz, spi->max_speed_hz);
 191         }
 192
 193         if (bits_per_word != 8) {
 194                 dev_err(&spi->dev, "invalid bits-per-word (%d)\n",
 195                                 bits_per_word);
 196                 return -EINVAL;
 197         }
 198
 199         if (!speed || (speed > spi->max_speed_hz)) {
 200                 dev_err(&spi->dev, "invalid speed_hz (%d)\n", speed);
 201                 return -EINVAL;
 202         }
 203
 204         /* Write new configuration */
 205         out_8(&hw->regs->mode, cs->mode);
 206
 207         /* Set the clock */
 208         /* opb_freq was already divided by 4 */
 209         scr = (hw->opb_freq / speed) - 1;
 210         if (scr > 0)
 211                 cdm = min(scr, 0xff);
 212
 213         dev_dbg(&spi->dev, "setting pre-scaler to %d (hz %d)\n", cdm, speed);
 214
 215         if (in_8(&hw->regs->cdm) != cdm)
 216                 out_8(&hw->regs->cdm, cdm);
 217
 218         spin_lock(&hw->bitbang.lock);
 219         if (!hw->bitbang.busy) {
 220                 hw->bitbang.chipselect(spi, BITBANG_CS_INACTIVE);
 221                 /* Need to ndelay here? */
 222         }
 223         spin_unlock(&hw->bitbang.lock);
 224
 225         return 0;
 226 }
 227
 228 static int spi_ppc4xx_setup(struct spi_device *spi)
 229 {
 230         struct spi_ppc4xx_cs *cs = spi->controller_state;
 231
 232         if (spi->bits_per_word != 8) {
 233                 dev_err(&spi->dev, "invalid bits-per-word (%d)\n",
 234                         spi->bits_per_word);
 235                 return -EINVAL;
 236         }
 237
 238         if (!spi->max_speed_hz) {
 239                 dev_err(&spi->dev, "invalid max_speed_hz (must be non-zero)\n");
 240                 return -EINVAL;
 241         }
 242
 243         if (cs == NULL) {
 244                 cs = kzalloc(sizeof *cs, GFP_KERNEL);
 245                 if (!cs)
 246                         return -ENOMEM;
 247                 spi->controller_state = cs;
 248         }
 249
 250         /*
 251          * We set all bits of the SPI0_MODE register, so,
 252          * no need to read-modify-write
 253          */
 254         cs->mode = SPI_PPC4XX_MODE_SPE;
 255
 256         switch (spi->mode & (SPI_CPHA | SPI_CPOL)) {
 257         case SPI_MODE_0:
 258                 cs->mode |= SPI_CLK_MODE0;
 259                 break;
 260         case SPI_MODE_1:
 261                 cs->mode |= SPI_CLK_MODE1;
 262                 break;
 263         case SPI_MODE_2:
 264                 cs->mode |= SPI_CLK_MODE2;
 265                 break;
 266         case SPI_MODE_3:
 267                 cs->mode |= SPI_CLK_MODE3;
 268                 break;
 269         }
 270
 271         if (spi->mode & SPI_LSB_FIRST)
 272                 cs->mode |= SPI_PPC4XX_MODE_RD;
 273
 274         return 0;
 275 }
 276
 277 static void spi_ppc4xx_chipsel(struct spi_device *spi, int value)
 278 {
 279         struct ppc4xx_spi *hw = spi_master_get_devdata(spi->master);
 280         unsigned int cs = spi->chip_select;
 281         unsigned int cspol;
 282
 283         /*
 284          * If there are no chip selects at all, or if this is the special
 285          * case of a non-existent (dummy) chip select, do nothing.
 286          */
 287
 288         if (!hw->master->num_chipselect || hw->gpios[cs] == -EEXIST)
 289                 return;
 290
 291         cspol = spi->mode & SPI_CS_HIGH ? 1 : 0;
 292         if (value == BITBANG_CS_INACTIVE)
 293                 cspol = !cspol;
 294
 295         gpio_set_value(hw->gpios[cs], cspol);
 296 }
 297
 298 static irqreturn_t spi_ppc4xx_int(int irq, void *dev_id)
 299 {
 300         struct ppc4xx_spi *hw;
 301         u8 status;
 302         u8 data;
 303         unsigned int count;
 304
 305         hw = (struct ppc4xx_spi *)dev_id;
 306
 307         status = in_8(&hw->regs->sr);
 308         if (!status)
 309                 return IRQ_NONE;
 310
 311         /*
 312          * BSY de-asserts one cycle after the transfer is complete.  The
 313          * interrupt is asserted after the transfer is complete.  The exact
 314          * relationship is not documented, hence this code.
 315          */
 316
 317         if (unlikely(status & SPI_PPC4XX_SR_BSY)) {
 318                 u8 lstatus;
 319                 int cnt = 0;
 320
 321                 dev_dbg(hw->dev, "got interrupt but spi still busy?\n");
 322                 do {
 323                         ndelay(10);
 324                         lstatus = in_8(&hw->regs->sr);
 325                 } while (++cnt < 100 && lstatus & SPI_PPC4XX_SR_BSY);
 326
 327                 if (cnt >= 100) {
 328                         dev_err(hw->dev, "busywait: too many loops!\n");
 329                         complete(&hw->done);
 330                         return IRQ_HANDLED;
 331                 } else {
 332                         /* status is always 1 (RBR) here */
 333                         status = in_8(&hw->regs->sr);
 334                         dev_dbg(hw->dev, "loops %d status %x\n", cnt, status);
 335                 }
 336         }
 337
 338         count = hw->count;
 339         hw->count++;
 340
 341         /* RBR triggered this interrupt.  Therefore, data must be ready. */
 342         data = in_8(&hw->regs->rxd);
 343         if (hw->rx)
 344                 hw->rx[count] = data;
 345
 346         count++;
 347
 348         if (count < hw->len) {
 349                 data = hw->tx ? hw->tx[count] : 0;
 350                 out_8(&hw->regs->txd, data);
 351                 out_8(&hw->regs->cr, SPI_PPC4XX_CR_STR);
 352         } else {
 353                 complete(&hw->done);
 354         }
 355
 356         return IRQ_HANDLED;
 357 }
 358
 359 static void spi_ppc4xx_cleanup(struct spi_device *spi)
 360 {
 361         kfree(spi->controller_state);
 362 }
 363
 364 static void spi_ppc4xx_enable(struct ppc4xx_spi *hw)
 365 {
 366         /*
 367          * On all 4xx PPC's the SPI bus is shared/multiplexed with
 368          * the 2nd I2C bus. We need to enable the the SPI bus before
 369          * using it.
 370          */
 371
 372         /* need to clear bit 14 to enable SPC */
 373         dcri_clrset(SDR0, SDR0_PFC1, 0x80000000 >> 14, 0);
 374 }
 375
 376 static void free_gpios(struct ppc4xx_spi *hw)
 377 {
 378         if (hw->master->num_chipselect) {
 379                 int i;
 380                 for (i = 0; i < hw->master->num_chipselect; i++)
 381                         if (gpio_is_valid(hw->gpios[i]))
 382                                 gpio_free(hw->gpios[i]);
 383
 384                 kfree(hw->gpios);
 385                 hw->gpios = NULL;
 386         }
 387 }
 388
 389 /*
 390  * platform_device layer stuff...
 391  */
 392 static int spi_ppc4xx_of_probe(struct platform_device *op)
 393 {
 394         struct ppc4xx_spi *hw;
 395         struct spi_master *master;
 396         struct spi_bitbang *bbp;
 397         struct resource resource;
 398         struct device_node *np = op->dev.of_node;
 399         struct device *dev = &op->dev;
 400         struct device_node *opbnp;
 401         int ret;
 402         int num_gpios;
 403         const unsigned int *clk;
 404
 405         master = spi_alloc_master(dev, sizeof *hw);
 406         if (master == NULL)
 407                 return -ENOMEM;
 408         master->dev.of_node = np;
 409         dev_set_drvdata(dev, master);
 410         hw = spi_master_get_devdata(master);
 411         hw->master = spi_master_get(master);
 412         hw->dev = dev;
 413
 414         init_completion(&hw->done);
 415
 416         /*
 417          * A count of zero implies a single SPI device without any chip-select.
 418          * Note that of_gpio_count counts all gpios assigned to this spi master.
 419          * This includes both "null" gpio's and real ones.
 420          */
 421         num_gpios = of_gpio_count(np);
 422         if (num_gpios > 0) {
 423                 int i;
 424
 425                 hw->gpios = kzalloc(sizeof(int) * num_gpios, GFP_KERNEL);
 426                 if (!hw->gpios) {
 427                         ret = -ENOMEM;
 428                         goto free_master;
 429                 }
 430
 431                 for (i = 0; i < num_gpios; i++) {
 432                         int gpio;
 433                         enum of_gpio_flags flags;
 434
 435                         gpio = of_get_gpio_flags(np, i, &flags);
 436                         hw->gpios[i] = gpio;
 437
 438                         if (gpio_is_valid(gpio)) {
 439                                 /* Real CS - set the initial state. */
 440                                 ret = gpio_request(gpio, np->name);
 441                                 if (ret < 0) {
 442                                         dev_err(dev, "can't request gpio "
 443                                                         "#%d: %d\n", i, ret);
 444                                         goto free_gpios;
 445                                 }
 446
 447                                 gpio_direction_output(gpio,
 448                                                 !!(flags & OF_GPIO_ACTIVE_LOW));
 449                         } else if (gpio == -EEXIST) {
 450                                 ; /* No CS, but that's OK. */
 451                         } else {
 452                                 dev_err(dev, "invalid gpio #%d: %d\n", i, gpio);
 453                                 ret = -EINVAL;
 454                                 goto free_gpios;
 455                         }
 456                 }
 457         }
 458
 459         /* Setup the state for the bitbang driver */
 460         bbp = &hw->bitbang;
 461         bbp->master = hw->master;
 462         bbp->setup_transfer = spi_ppc4xx_setupxfer;
 463         bbp->chipselect = spi_ppc4xx_chipsel;
 464         bbp->txrx_bufs = spi_ppc4xx_txrx;
 465         bbp->use_dma = 0;
 466         bbp->master->setup = spi_ppc4xx_setup;
 467         bbp->master->cleanup = spi_ppc4xx_cleanup;
 468
 469         /* the spi->mode bits understood by this driver: */
 470         bbp->master->mode_bits =
 471                 SPI_CPHA | SPI_CPOL | SPI_CS_HIGH | SPI_LSB_FIRST;
 472
 473         /* this many pins in all GPIO controllers */
 474         bbp->master->num_chipselect = num_gpios > 0 ? num_gpios : 0;
 475
 476         /* Get the clock for the OPB */
 477         opbnp = of_find_compatible_node(NULL, NULL, "ibm,opb");
 478         if (opbnp == NULL) {
 479                 dev_err(dev, "OPB: cannot find node\n");
 480                 ret = -ENODEV;
 481                 goto free_gpios;
 482         }
 483         /* Get the clock (Hz) for the OPB */
 484         clk = of_get_property(opbnp, "clock-frequency", NULL);
 485         if (clk == NULL) {
 486                 dev_err(dev, "OPB: no clock-frequency property set\n");
 487                 of_node_put(opbnp);
 488                 ret = -ENODEV;
 489                 goto free_gpios;
 490         }
 491         hw->opb_freq = *clk;
 492         hw->opb_freq >>= 2;
 493         of_node_put(opbnp);
 494
 495         ret = of_address_to_resource(np, 0, &resource);
 496         if (ret) {
 497                 dev_err(dev, "error while parsing device node resource\n");
 498                 goto free_gpios;
 499         }
 500         hw->mapbase = resource.start;
 501         hw->mapsize = resource_size(&resource);
 502
 503         /* Sanity check */
 504         if (hw->mapsize < sizeof(struct spi_ppc4xx_regs)) {
 505                 dev_err(dev, "too small to map registers\n");
 506                 ret = -EINVAL;
 507                 goto free_gpios;
 508         }
 509
 510         /* Request IRQ */
 511         hw->irqnum = irq_of_parse_and_map(np, 0);
 512         ret = request_irq(hw->irqnum, spi_ppc4xx_int,
 513                           0, "spi_ppc4xx_of", (void *)hw);
 514         if (ret) {
 515                 dev_err(dev, "unable to allocate interrupt\n");
 516                 goto free_gpios;
 517         }
 518
 519         if (!request_mem_region(hw->mapbase, hw->mapsize, DRIVER_NAME)) {
 520                 dev_err(dev, "resource unavailable\n");
 521                 ret = -EBUSY;
 522                 goto request_mem_error;
 523         }
 524
 525         hw->regs = ioremap(hw->mapbase, sizeof(struct spi_ppc4xx_regs));
 526
 527         if (!hw->regs) {
 528                 dev_err(dev, "unable to memory map registers\n");
 529                 ret = -ENXIO;
 530                 goto map_io_error;
 531         }
 532
 533         spi_ppc4xx_enable(hw);
 534
 535         /* Finally register our spi controller */
 536         dev->dma_mask = 0;
 537         ret = spi_bitbang_start(bbp);
 538         if (ret) {
 539                 dev_err(dev, "failed to register SPI master\n");
 540                 goto unmap_regs;
 541         }
 542
 543         dev_info(dev, "driver initialized\n");
 544
 545         return 0;
 546
 547 unmap_regs:
 548         iounmap(hw->regs);
 549 map_io_error:
 550         release_mem_region(hw->mapbase, hw->mapsize);
 551 request_mem_error:
 552         free_irq(hw->irqnum, hw);
 553 free_gpios:
 554         free_gpios(hw);
 555 free_master:
 556         dev_set_drvdata(dev, NULL);
 557         spi_master_put(master);
 558
 559         dev_err(dev, "initialization failed\n");
 560         return ret;
 561 }
 562
 563 static int spi_ppc4xx_of_remove(struct platform_device *op)
 564 {
 565         struct spi_master *master = dev_get_drvdata(&op->dev);
 566         struct ppc4xx_spi *hw = spi_master_get_devdata(master);
 567
 568         spi_bitbang_stop(&hw->bitbang);
 569         dev_set_drvdata(&op->dev, NULL);
 570         release_mem_region(hw->mapbase, hw->mapsize);
 571         free_irq(hw->irqnum, hw);
 572         iounmap(hw->regs);
 573         free_gpios(hw);
 574         return 0;
 575 }
 576
 577 static const struct of_device_id spi_ppc4xx_of_match[] = {
 578         { .compatible = "ibm,ppc4xx-spi", },
 579         {},
 580 };
 581
 582 MODULE_DEVICE_TABLE(of, spi_ppc4xx_of_match);
 583
 584 static struct platform_driver spi_ppc4xx_of_driver = {
 585         .probe = spi_ppc4xx_of_probe,
 586         .remove = spi_ppc4xx_of_remove,
 587         .driver = {
 588                 .name = DRIVER_NAME,
 589                 .owner = THIS_MODULE,
 590                 .of_match_table = spi_ppc4xx_of_match,
 591         },
 592 };
 593 module_platform_driver(spi_ppc4xx_of_driver);
 594
 595 MODULE_AUTHOR("Gary Jennejohn & Stefan Roese");
 596 MODULE_DESCRIPTION("Simple PPC4xx SPI Driver");
 597 MODULE_LICENSE("GPL");