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