kernel/drivers/spi/spi-orion.c

   1 /*
   2  * Marvell Orion SPI controller driver
   3  *
   4  * Author: Shadi Ammouri <shadi@marvell.com>
   5  * Copyright (C) 2007-2008 Marvell Ltd.
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License version 2 as
   9  * published by the Free Software Foundation.
  10  */
  11
  12 #include <linux/interrupt.h>
  13 #include <linux/delay.h>
  14 #include <linux/platform_device.h>
  15 #include <linux/err.h>
  16 #include <linux/io.h>
  17 #include <linux/spi/spi.h>
  18 #include <linux/module.h>
  19 #include <linux/pm_runtime.h>
  20 #include <linux/of.h>
  21 #include <linux/of_device.h>
  22 #include <linux/clk.h>
  23 #include <linux/sizes.h>
  24 #include <asm/unaligned.h>
  25
  26 #define DRIVER_NAME                     "orion_spi"
  27
  28 /* Runtime PM autosuspend timeout: PM is fairly light on this driver */
  29 #define SPI_AUTOSUSPEND_TIMEOUT         200
  30
  31 /* Some SoCs using this driver support up to 8 chip selects.
  32  * It is up to the implementer to only use the chip selects
  33  * that are available.
  34  */
  35 #define ORION_NUM_CHIPSELECTS           8
  36
  37 #define ORION_SPI_WAIT_RDY_MAX_LOOP     2000 /* in usec */
  38
  39 #define ORION_SPI_IF_CTRL_REG           0x00
  40 #define ORION_SPI_IF_CONFIG_REG         0x04
  41 #define ORION_SPI_DATA_OUT_REG          0x08
  42 #define ORION_SPI_DATA_IN_REG           0x0c
  43 #define ORION_SPI_INT_CAUSE_REG         0x10
  44
  45 #define ORION_SPI_MODE_CPOL             (1 << 11)
  46 #define ORION_SPI_MODE_CPHA             (1 << 12)
  47 #define ORION_SPI_IF_8_16_BIT_MODE      (1 << 5)
  48 #define ORION_SPI_CLK_PRESCALE_MASK     0x1F
  49 #define ARMADA_SPI_CLK_PRESCALE_MASK    0xDF
  50 #define ORION_SPI_MODE_MASK             (ORION_SPI_MODE_CPOL | \
  51                                          ORION_SPI_MODE_CPHA)
  52 #define ORION_SPI_CS_MASK       0x1C
  53 #define ORION_SPI_CS_SHIFT      2
  54 #define ORION_SPI_CS(cs)        ((cs << ORION_SPI_CS_SHIFT) & \
  55                                         ORION_SPI_CS_MASK)
  56
  57 enum orion_spi_type {
  58         ORION_SPI,
  59         ARMADA_SPI,
  60 };
  61
  62 struct orion_spi_dev {
  63         enum orion_spi_type     typ;
  64         /*
  65          * min_divisor and max_hz should be exclusive, the only we can
  66          * have both is for managing the armada-370-spi case with old
  67          * device tree
  68          */
  69         unsigned long           max_hz;
  70         unsigned int            min_divisor;
  71         unsigned int            max_divisor;
  72         u32                     prescale_mask;
  73 };
  74
  75 struct orion_spi {
  76         struct spi_master       *master;
  77         void __iomem            *base;
  78         struct clk              *clk;
  79         const struct orion_spi_dev *devdata;
  80 };
  81
  82 static inline void __iomem *spi_reg(struct orion_spi *orion_spi, u32 reg)
  83 {
  84         return orion_spi->base + reg;
  85 }
  86
  87 static inline void
  88 orion_spi_setbits(struct orion_spi *orion_spi, u32 reg, u32 mask)
  89 {
  90         void __iomem *reg_addr = spi_reg(orion_spi, reg);
  91         u32 val;
  92
  93         val = readl(reg_addr);
  94         val |= mask;
  95         writel(val, reg_addr);
  96 }
  97
  98 static inline void
  99 orion_spi_clrbits(struct orion_spi *orion_spi, u32 reg, u32 mask)
 100 {
 101         void __iomem *reg_addr = spi_reg(orion_spi, reg);
 102         u32 val;
 103
 104         val = readl(reg_addr);
 105         val &= ~mask;
 106         writel(val, reg_addr);
 107 }
 108
 109 static int orion_spi_baudrate_set(struct spi_device *spi, unsigned int speed)
 110 {
 111         u32 tclk_hz;
 112         u32 rate;
 113         u32 prescale;
 114         u32 reg;
 115         struct orion_spi *orion_spi;
 116         const struct orion_spi_dev *devdata;
 117
 118         orion_spi = spi_master_get_devdata(spi->master);
 119         devdata = orion_spi->devdata;
 120
 121         tclk_hz = clk_get_rate(orion_spi->clk);
 122
 123         if (devdata->typ == ARMADA_SPI) {
 124                 unsigned int clk, spr, sppr, sppr2, err;
 125                 unsigned int best_spr, best_sppr, best_err;
 126
 127                 best_err = speed;
 128                 best_spr = 0;
 129                 best_sppr = 0;
 130
 131                 /* Iterate over the valid range looking for best fit */
 132                 for (sppr = 0; sppr < 8; sppr++) {
 133                         sppr2 = 0x1 << sppr;
 134
 135                         spr = tclk_hz / sppr2;
 136                         spr = DIV_ROUND_UP(spr, speed);
 137                         if ((spr == 0) || (spr > 15))
 138                                 continue;
 139
 140                         clk = tclk_hz / (spr * sppr2);
 141                         err = speed - clk;
 142
 143                         if (err < best_err) {
 144                                 best_spr = spr;
 145                                 best_sppr = sppr;
 146                                 best_err = err;
 147                         }
 148                 }
 149
 150                 if ((best_sppr == 0) && (best_spr == 0))
 151                         return -EINVAL;
 152
 153                 prescale = ((best_sppr & 0x6) << 5) |
 154                         ((best_sppr & 0x1) << 4) | best_spr;
 155         } else {
 156                 /*
 157                  * the supported rates are: 4,6,8...30
 158                  * round up as we look for equal or less speed
 159                  */
 160                 rate = DIV_ROUND_UP(tclk_hz, speed);
 161                 rate = roundup(rate, 2);
 162
 163                 /* check if requested speed is too small */
 164                 if (rate > 30)
 165                         return -EINVAL;
 166
 167                 if (rate < 4)
 168                         rate = 4;
 169
 170                 /* Convert the rate to SPI clock divisor value. */
 171                 prescale = 0x10 + rate/2;
 172         }
 173
 174         reg = readl(spi_reg(orion_spi, ORION_SPI_IF_CONFIG_REG));
 175         reg = ((reg & ~devdata->prescale_mask) | prescale);
 176         writel(reg, spi_reg(orion_spi, ORION_SPI_IF_CONFIG_REG));
 177
 178         return 0;
 179 }
 180
 181 static void
 182 orion_spi_mode_set(struct spi_device *spi)
 183 {
 184         u32 reg;
 185         struct orion_spi *orion_spi;
 186
 187         orion_spi = spi_master_get_devdata(spi->master);
 188
 189         reg = readl(spi_reg(orion_spi, ORION_SPI_IF_CONFIG_REG));
 190         reg &= ~ORION_SPI_MODE_MASK;
 191         if (spi->mode & SPI_CPOL)
 192                 reg |= ORION_SPI_MODE_CPOL;
 193         if (spi->mode & SPI_CPHA)
 194                 reg |= ORION_SPI_MODE_CPHA;
 195         writel(reg, spi_reg(orion_spi, ORION_SPI_IF_CONFIG_REG));
 196 }
 197
 198 /*
 199  * called only when no transfer is active on the bus
 200  */
 201 static int
 202 orion_spi_setup_transfer(struct spi_device *spi, struct spi_transfer *t)
 203 {
 204         struct orion_spi *orion_spi;
 205         unsigned int speed = spi->max_speed_hz;
 206         unsigned int bits_per_word = spi->bits_per_word;
 207         int     rc;
 208
 209         orion_spi = spi_master_get_devdata(spi->master);
 210
 211         if ((t != NULL) && t->speed_hz)
 212                 speed = t->speed_hz;
 213
 214         if ((t != NULL) && t->bits_per_word)
 215                 bits_per_word = t->bits_per_word;
 216
 217         orion_spi_mode_set(spi);
 218
 219         rc = orion_spi_baudrate_set(spi, speed);
 220         if (rc)
 221                 return rc;
 222
 223         if (bits_per_word == 16)
 224                 orion_spi_setbits(orion_spi, ORION_SPI_IF_CONFIG_REG,
 225                                   ORION_SPI_IF_8_16_BIT_MODE);
 226         else
 227                 orion_spi_clrbits(orion_spi, ORION_SPI_IF_CONFIG_REG,
 228                                   ORION_SPI_IF_8_16_BIT_MODE);
 229
 230         return 0;
 231 }
 232
 233 static void orion_spi_set_cs(struct spi_device *spi, bool enable)
 234 {
 235         struct orion_spi *orion_spi;
 236
 237         orion_spi = spi_master_get_devdata(spi->master);
 238
 239         orion_spi_clrbits(orion_spi, ORION_SPI_IF_CTRL_REG, ORION_SPI_CS_MASK);
 240         orion_spi_setbits(orion_spi, ORION_SPI_IF_CTRL_REG,
 241                                 ORION_SPI_CS(spi->chip_select));
 242
 243         /* Chip select logic is inverted from spi_set_cs */
 244         if (!enable)
 245                 orion_spi_setbits(orion_spi, ORION_SPI_IF_CTRL_REG, 0x1);
 246         else
 247                 orion_spi_clrbits(orion_spi, ORION_SPI_IF_CTRL_REG, 0x1);
 248 }
 249
 250 static inline int orion_spi_wait_till_ready(struct orion_spi *orion_spi)
 251 {
 252         int i;
 253
 254         for (i = 0; i < ORION_SPI_WAIT_RDY_MAX_LOOP; i++) {
 255                 if (readl(spi_reg(orion_spi, ORION_SPI_INT_CAUSE_REG)))
 256                         return 1;
 257
 258                 udelay(1);
 259         }
 260
 261         return -1;
 262 }
 263
 264 static inline int
 265 orion_spi_write_read_8bit(struct spi_device *spi,
 266                           const u8 **tx_buf, u8 **rx_buf)
 267 {
 268         void __iomem *tx_reg, *rx_reg, *int_reg;
 269         struct orion_spi *orion_spi;
 270
 271         orion_spi = spi_master_get_devdata(spi->master);
 272         tx_reg = spi_reg(orion_spi, ORION_SPI_DATA_OUT_REG);
 273         rx_reg = spi_reg(orion_spi, ORION_SPI_DATA_IN_REG);
 274         int_reg = spi_reg(orion_spi, ORION_SPI_INT_CAUSE_REG);
 275
 276         /* clear the interrupt cause register */
 277         writel(0x0, int_reg);
 278
 279         if (tx_buf && *tx_buf)
 280                 writel(*(*tx_buf)++, tx_reg);
 281         else
 282                 writel(0, tx_reg);
 283
 284         if (orion_spi_wait_till_ready(orion_spi) < 0) {
 285                 dev_err(&spi->dev, "TXS timed out\n");
 286                 return -1;
 287         }
 288
 289         if (rx_buf && *rx_buf)
 290                 *(*rx_buf)++ = readl(rx_reg);
 291
 292         return 1;
 293 }
 294
 295 static inline int
 296 orion_spi_write_read_16bit(struct spi_device *spi,
 297                            const u16 **tx_buf, u16 **rx_buf)
 298 {
 299         void __iomem *tx_reg, *rx_reg, *int_reg;
 300         struct orion_spi *orion_spi;
 301
 302         orion_spi = spi_master_get_devdata(spi->master);
 303         tx_reg = spi_reg(orion_spi, ORION_SPI_DATA_OUT_REG);
 304         rx_reg = spi_reg(orion_spi, ORION_SPI_DATA_IN_REG);
 305         int_reg = spi_reg(orion_spi, ORION_SPI_INT_CAUSE_REG);
 306
 307         /* clear the interrupt cause register */
 308         writel(0x0, int_reg);
 309
 310         if (tx_buf && *tx_buf)
 311                 writel(__cpu_to_le16(get_unaligned((*tx_buf)++)), tx_reg);
 312         else
 313                 writel(0, tx_reg);
 314
 315         if (orion_spi_wait_till_ready(orion_spi) < 0) {
 316                 dev_err(&spi->dev, "TXS timed out\n");
 317                 return -1;
 318         }
 319
 320         if (rx_buf && *rx_buf)
 321                 put_unaligned(__le16_to_cpu(readl(rx_reg)), (*rx_buf)++);
 322
 323         return 1;
 324 }
 325
 326 static unsigned int
 327 orion_spi_write_read(struct spi_device *spi, struct spi_transfer *xfer)
 328 {
 329         unsigned int count;
 330         int word_len;
 331
 332         word_len = spi->bits_per_word;
 333         count = xfer->len;
 334
 335         if (word_len == 8) {
 336                 const u8 *tx = xfer->tx_buf;
 337                 u8 *rx = xfer->rx_buf;
 338
 339                 do {
 340                         if (orion_spi_write_read_8bit(spi, &tx, &rx) < 0)
 341                                 goto out;
 342                         count--;
 343                 } while (count);
 344         } else if (word_len == 16) {
 345                 const u16 *tx = xfer->tx_buf;
 346                 u16 *rx = xfer->rx_buf;
 347
 348                 do {
 349                         if (orion_spi_write_read_16bit(spi, &tx, &rx) < 0)
 350                                 goto out;
 351                         count -= 2;
 352                 } while (count);
 353         }
 354
 355 out:
 356         return xfer->len - count;
 357 }
 358
 359 static int orion_spi_transfer_one(struct spi_master *master,
 360                                         struct spi_device *spi,
 361                                         struct spi_transfer *t)
 362 {
 363         int status = 0;
 364
 365         status = orion_spi_setup_transfer(spi, t);
 366         if (status < 0)
 367                 return status;
 368
 369         if (t->len)
 370                 orion_spi_write_read(spi, t);
 371
 372         return status;
 373 }
 374
 375 static int orion_spi_setup(struct spi_device *spi)
 376 {
 377         return orion_spi_setup_transfer(spi, NULL);
 378 }
 379
 380 static int orion_spi_reset(struct orion_spi *orion_spi)
 381 {
 382         /* Verify that the CS is deasserted */
 383         orion_spi_clrbits(orion_spi, ORION_SPI_IF_CTRL_REG, 0x1);
 384         return 0;
 385 }
 386
 387 static const struct orion_spi_dev orion_spi_dev_data = {
 388         .typ = ORION_SPI,
 389         .min_divisor = 4,
 390         .max_divisor = 30,
 391         .prescale_mask = ORION_SPI_CLK_PRESCALE_MASK,
 392 };
 393
 394 static const struct orion_spi_dev armada_spi_dev_data = {
 395         .typ = ARMADA_SPI,
 396         .min_divisor = 4,
 397         .max_divisor = 1920,
 398         .max_hz = 50000000,
 399         .prescale_mask = ARMADA_SPI_CLK_PRESCALE_MASK,
 400 };
 401
 402 static const struct of_device_id orion_spi_of_match_table[] = {
 403         { .compatible = "marvell,orion-spi", .data = &orion_spi_dev_data, },
 404         { .compatible = "marvell,armada-370-spi", .data = &armada_spi_dev_data, },
 405         {}
 406 };
 407 MODULE_DEVICE_TABLE(of, orion_spi_of_match_table);
 408
 409 static int orion_spi_probe(struct platform_device *pdev)
 410 {
 411         const struct of_device_id *of_id;
 412         const struct orion_spi_dev *devdata;
 413         struct spi_master *master;
 414         struct orion_spi *spi;
 415         struct resource *r;
 416         unsigned long tclk_hz;
 417         int status = 0;
 418
 419         master = spi_alloc_master(&pdev->dev, sizeof(*spi));
 420         if (master == NULL) {
 421                 dev_dbg(&pdev->dev, "master allocation failed\n");
 422                 return -ENOMEM;
 423         }
 424
 425         if (pdev->id != -1)
 426                 master->bus_num = pdev->id;
 427         if (pdev->dev.of_node) {
 428                 u32 cell_index;
 429
 430                 if (!of_property_read_u32(pdev->dev.of_node, "cell-index",
 431                                           &cell_index))
 432                         master->bus_num = cell_index;
 433         }
 434
 435         /* we support only mode 0, and no options */
 436         master->mode_bits = SPI_CPHA | SPI_CPOL;
 437         master->set_cs = orion_spi_set_cs;
 438         master->transfer_one = orion_spi_transfer_one;
 439         master->num_chipselect = ORION_NUM_CHIPSELECTS;
 440         master->setup = orion_spi_setup;
 441         master->bits_per_word_mask = SPI_BPW_MASK(8) | SPI_BPW_MASK(16);
 442         master->auto_runtime_pm = true;
 443
 444         platform_set_drvdata(pdev, master);
 445
 446         spi = spi_master_get_devdata(master);
 447         spi->master = master;
 448
 449         of_id = of_match_device(orion_spi_of_match_table, &pdev->dev);
 450         devdata = (of_id) ? of_id->data : &orion_spi_dev_data;
 451         spi->devdata = devdata;
 452
 453         spi->clk = devm_clk_get(&pdev->dev, NULL);
 454         if (IS_ERR(spi->clk)) {
 455                 status = PTR_ERR(spi->clk);
 456                 goto out;
 457         }
 458
 459         status = clk_prepare_enable(spi->clk);
 460         if (status)
 461                 goto out;
 462
 463         tclk_hz = clk_get_rate(spi->clk);
 464
 465         /*
 466          * With old device tree, armada-370-spi could be used with
 467          * Armada XP, however for this SoC the maximum frequency is
 468          * 50MHz instead of tclk/4. On Armada 370, tclk cannot be
 469          * higher than 200MHz. So, in order to be able to handle both
 470          * SoCs, we can take the minimum of 50MHz and tclk/4.
 471          */
 472         if (of_device_is_compatible(pdev->dev.of_node,
 473                                         "marvell,armada-370-spi"))
 474                 master->max_speed_hz = min(devdata->max_hz,
 475                                 DIV_ROUND_UP(tclk_hz, devdata->min_divisor));
 476         else
 477                 master->max_speed_hz =
 478                         DIV_ROUND_UP(tclk_hz, devdata->min_divisor);
 479         master->min_speed_hz = DIV_ROUND_UP(tclk_hz, devdata->max_divisor);
 480
 481         r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 482         spi->base = devm_ioremap_resource(&pdev->dev, r);
 483         if (IS_ERR(spi->base)) {
 484                 status = PTR_ERR(spi->base);
 485                 goto out_rel_clk;
 486         }
 487
 488         pm_runtime_set_active(&pdev->dev);
 489         pm_runtime_use_autosuspend(&pdev->dev);
 490         pm_runtime_set_autosuspend_delay(&pdev->dev, SPI_AUTOSUSPEND_TIMEOUT);
 491         pm_runtime_enable(&pdev->dev);
 492
 493         status = orion_spi_reset(spi);
 494         if (status < 0)
 495                 goto out_rel_pm;
 496
 497         pm_runtime_mark_last_busy(&pdev->dev);
 498         pm_runtime_put_autosuspend(&pdev->dev);
 499
 500         master->dev.of_node = pdev->dev.of_node;
 501         status = spi_register_master(master);
 502         if (status < 0)
 503                 goto out_rel_pm;
 504
 505         return status;
 506
 507 out_rel_pm:
 508         pm_runtime_disable(&pdev->dev);
 509 out_rel_clk:
 510         clk_disable_unprepare(spi->clk);
 511 out:
 512         spi_master_put(master);
 513         return status;
 514 }
 515
 516
 517 static int orion_spi_remove(struct platform_device *pdev)
 518 {
 519         struct spi_master *master = platform_get_drvdata(pdev);
 520         struct orion_spi *spi = spi_master_get_devdata(master);
 521
 522         pm_runtime_get_sync(&pdev->dev);
 523         clk_disable_unprepare(spi->clk);
 524
 525         spi_unregister_master(master);
 526         pm_runtime_disable(&pdev->dev);
 527
 528         return 0;
 529 }
 530
 531 MODULE_ALIAS("platform:" DRIVER_NAME);
 532
 533 #ifdef CONFIG_PM
 534 static int orion_spi_runtime_suspend(struct device *dev)
 535 {
 536         struct spi_master *master = dev_get_drvdata(dev);
 537         struct orion_spi *spi = spi_master_get_devdata(master);
 538
 539         clk_disable_unprepare(spi->clk);
 540         return 0;
 541 }
 542
 543 static int orion_spi_runtime_resume(struct device *dev)
 544 {
 545         struct spi_master *master = dev_get_drvdata(dev);
 546         struct orion_spi *spi = spi_master_get_devdata(master);
 547
 548         return clk_prepare_enable(spi->clk);
 549 }
 550 #endif
 551
 552 static const struct dev_pm_ops orion_spi_pm_ops = {
 553         SET_RUNTIME_PM_OPS(orion_spi_runtime_suspend,
 554                            orion_spi_runtime_resume,
 555                            NULL)
 556 };
 557
 558 static struct platform_driver orion_spi_driver = {
 559         .driver = {
 560                 .name   = DRIVER_NAME,
 561                 .pm     = &orion_spi_pm_ops,
 562                 .of_match_table = of_match_ptr(orion_spi_of_match_table),
 563         },
 564         .probe          = orion_spi_probe,
 565         .remove         = orion_spi_remove,
 566 };
 567
 568 module_platform_driver(orion_spi_driver);
 569
 570 MODULE_DESCRIPTION("Orion SPI driver");
 571 MODULE_AUTHOR("Shadi Ammouri <shadi@marvell.com>");
 572 MODULE_LICENSE("GPL");