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/init.h>
  13 #include <linux/interrupt.h>
  14 #include <linux/delay.h>
  15 #include <linux/platform_device.h>
  16 #include <linux/err.h>
  17 #include <linux/io.h>
  18 #include <linux/spi/spi.h>
  19 #include <linux/module.h>
  20 #include <linux/clk.h>
  21 #include <asm/unaligned.h>
  22
  23 #define DRIVER_NAME                     "orion_spi"
  24
  25 #define ORION_NUM_CHIPSELECTS           1 /* only one slave is supported*/
  26 #define ORION_SPI_WAIT_RDY_MAX_LOOP     2000 /* in usec */
  27
  28 #define ORION_SPI_IF_CTRL_REG           0x00
  29 #define ORION_SPI_IF_CONFIG_REG         0x04
  30 #define ORION_SPI_DATA_OUT_REG          0x08
  31 #define ORION_SPI_DATA_IN_REG           0x0c
  32 #define ORION_SPI_INT_CAUSE_REG         0x10
  33
  34 #define ORION_SPI_IF_8_16_BIT_MODE      (1 << 5)
  35 #define ORION_SPI_CLK_PRESCALE_MASK     0x1F
  36
  37 struct orion_spi {
  38         struct work_struct      work;
  39
  40         /* Lock access to transfer list.        */
  41         spinlock_t              lock;
  42
  43         struct list_head        msg_queue;
  44         struct spi_master       *master;
  45         void __iomem            *base;
  46         unsigned int            max_speed;
  47         unsigned int            min_speed;
  48         struct orion_spi_info   *spi_info;
  49         struct clk              *clk;
  50 };
  51
  52 static struct workqueue_struct *orion_spi_wq;
  53
  54 static inline void __iomem *spi_reg(struct orion_spi *orion_spi, u32 reg)
  55 {
  56         return orion_spi->base + reg;
  57 }
  58
  59 static inline void
  60 orion_spi_setbits(struct orion_spi *orion_spi, u32 reg, u32 mask)
  61 {
  62         void __iomem *reg_addr = spi_reg(orion_spi, reg);
  63         u32 val;
  64
  65         val = readl(reg_addr);
  66         val |= mask;
  67         writel(val, reg_addr);
  68 }
  69
  70 static inline void
  71 orion_spi_clrbits(struct orion_spi *orion_spi, u32 reg, u32 mask)
  72 {
  73         void __iomem *reg_addr = spi_reg(orion_spi, reg);
  74         u32 val;
  75
  76         val = readl(reg_addr);
  77         val &= ~mask;
  78         writel(val, reg_addr);
  79 }
  80
  81 static int orion_spi_set_transfer_size(struct orion_spi *orion_spi, int size)
  82 {
  83         if (size == 16) {
  84                 orion_spi_setbits(orion_spi, ORION_SPI_IF_CONFIG_REG,
  85                                   ORION_SPI_IF_8_16_BIT_MODE);
  86         } else if (size == 8) {
  87                 orion_spi_clrbits(orion_spi, ORION_SPI_IF_CONFIG_REG,
  88                                   ORION_SPI_IF_8_16_BIT_MODE);
  89         } else {
  90                 pr_debug("Bad bits per word value %d (only 8 or 16 are "
  91                          "allowed).\n", size);
  92                 return -EINVAL;
  93         }
  94
  95         return 0;
  96 }
  97
  98 static int orion_spi_baudrate_set(struct spi_device *spi, unsigned int speed)
  99 {
 100         u32 tclk_hz;
 101         u32 rate;
 102         u32 prescale;
 103         u32 reg;
 104         struct orion_spi *orion_spi;
 105
 106         orion_spi = spi_master_get_devdata(spi->master);
 107
 108         tclk_hz = clk_get_rate(orion_spi->clk);
 109
 110         /*
 111          * the supported rates are: 4,6,8...30
 112          * round up as we look for equal or less speed
 113          */
 114         rate = DIV_ROUND_UP(tclk_hz, speed);
 115         rate = roundup(rate, 2);
 116
 117         /* check if requested speed is too small */
 118         if (rate > 30)
 119                 return -EINVAL;
 120
 121         if (rate < 4)
 122                 rate = 4;
 123
 124         /* Convert the rate to SPI clock divisor value. */
 125         prescale = 0x10 + rate/2;
 126
 127         reg = readl(spi_reg(orion_spi, ORION_SPI_IF_CONFIG_REG));
 128         reg = ((reg & ~ORION_SPI_CLK_PRESCALE_MASK) | prescale);
 129         writel(reg, spi_reg(orion_spi, ORION_SPI_IF_CONFIG_REG));
 130
 131         return 0;
 132 }
 133
 134 /*
 135  * called only when no transfer is active on the bus
 136  */
 137 static int
 138 orion_spi_setup_transfer(struct spi_device *spi, struct spi_transfer *t)
 139 {
 140         struct orion_spi *orion_spi;
 141         unsigned int speed = spi->max_speed_hz;
 142         unsigned int bits_per_word = spi->bits_per_word;
 143         int     rc;
 144
 145         orion_spi = spi_master_get_devdata(spi->master);
 146
 147         if ((t != NULL) && t->speed_hz)
 148                 speed = t->speed_hz;
 149
 150         if ((t != NULL) && t->bits_per_word)
 151                 bits_per_word = t->bits_per_word;
 152
 153         rc = orion_spi_baudrate_set(spi, speed);
 154         if (rc)
 155                 return rc;
 156
 157         return orion_spi_set_transfer_size(orion_spi, bits_per_word);
 158 }
 159
 160 static void orion_spi_set_cs(struct orion_spi *orion_spi, int enable)
 161 {
 162         if (enable)
 163                 orion_spi_setbits(orion_spi, ORION_SPI_IF_CTRL_REG, 0x1);
 164         else
 165                 orion_spi_clrbits(orion_spi, ORION_SPI_IF_CTRL_REG, 0x1);
 166 }
 167
 168 static inline int orion_spi_wait_till_ready(struct orion_spi *orion_spi)
 169 {
 170         int i;
 171
 172         for (i = 0; i < ORION_SPI_WAIT_RDY_MAX_LOOP; i++) {
 173                 if (readl(spi_reg(orion_spi, ORION_SPI_INT_CAUSE_REG)))
 174                         return 1;
 175                 else
 176                         udelay(1);
 177         }
 178
 179         return -1;
 180 }
 181
 182 static inline int
 183 orion_spi_write_read_8bit(struct spi_device *spi,
 184                           const u8 **tx_buf, u8 **rx_buf)
 185 {
 186         void __iomem *tx_reg, *rx_reg, *int_reg;
 187         struct orion_spi *orion_spi;
 188
 189         orion_spi = spi_master_get_devdata(spi->master);
 190         tx_reg = spi_reg(orion_spi, ORION_SPI_DATA_OUT_REG);
 191         rx_reg = spi_reg(orion_spi, ORION_SPI_DATA_IN_REG);
 192         int_reg = spi_reg(orion_spi, ORION_SPI_INT_CAUSE_REG);
 193
 194         /* clear the interrupt cause register */
 195         writel(0x0, int_reg);
 196
 197         if (tx_buf && *tx_buf)
 198                 writel(*(*tx_buf)++, tx_reg);
 199         else
 200                 writel(0, tx_reg);
 201
 202         if (orion_spi_wait_till_ready(orion_spi) < 0) {
 203                 dev_err(&spi->dev, "TXS timed out\n");
 204                 return -1;
 205         }
 206
 207         if (rx_buf && *rx_buf)
 208                 *(*rx_buf)++ = readl(rx_reg);
 209
 210         return 1;
 211 }
 212
 213 static inline int
 214 orion_spi_write_read_16bit(struct spi_device *spi,
 215                            const u16 **tx_buf, u16 **rx_buf)
 216 {
 217         void __iomem *tx_reg, *rx_reg, *int_reg;
 218         struct orion_spi *orion_spi;
 219
 220         orion_spi = spi_master_get_devdata(spi->master);
 221         tx_reg = spi_reg(orion_spi, ORION_SPI_DATA_OUT_REG);
 222         rx_reg = spi_reg(orion_spi, ORION_SPI_DATA_IN_REG);
 223         int_reg = spi_reg(orion_spi, ORION_SPI_INT_CAUSE_REG);
 224
 225         /* clear the interrupt cause register */
 226         writel(0x0, int_reg);
 227
 228         if (tx_buf && *tx_buf)
 229                 writel(__cpu_to_le16(get_unaligned((*tx_buf)++)), tx_reg);
 230         else
 231                 writel(0, tx_reg);
 232
 233         if (orion_spi_wait_till_ready(orion_spi) < 0) {
 234                 dev_err(&spi->dev, "TXS timed out\n");
 235                 return -1;
 236         }
 237
 238         if (rx_buf && *rx_buf)
 239                 put_unaligned(__le16_to_cpu(readl(rx_reg)), (*rx_buf)++);
 240
 241         return 1;
 242 }
 243
 244 static unsigned int
 245 orion_spi_write_read(struct spi_device *spi, struct spi_transfer *xfer)
 246 {
 247         struct orion_spi *orion_spi;
 248         unsigned int count;
 249         int word_len;
 250
 251         orion_spi = spi_master_get_devdata(spi->master);
 252         word_len = spi->bits_per_word;
 253         count = xfer->len;
 254
 255         if (word_len == 8) {
 256                 const u8 *tx = xfer->tx_buf;
 257                 u8 *rx = xfer->rx_buf;
 258
 259                 do {
 260                         if (orion_spi_write_read_8bit(spi, &tx, &rx) < 0)
 261                                 goto out;
 262                         count--;
 263                 } while (count);
 264         } else if (word_len == 16) {
 265                 const u16 *tx = xfer->tx_buf;
 266                 u16 *rx = xfer->rx_buf;
 267
 268                 do {
 269                         if (orion_spi_write_read_16bit(spi, &tx, &rx) < 0)
 270                                 goto out;
 271                         count -= 2;
 272                 } while (count);
 273         }
 274
 275 out:
 276         return xfer->len - count;
 277 }
 278
 279
 280 static void orion_spi_work(struct work_struct *work)
 281 {
 282         struct orion_spi *orion_spi =
 283                 container_of(work, struct orion_spi, work);
 284
 285         spin_lock_irq(&orion_spi->lock);
 286         while (!list_empty(&orion_spi->msg_queue)) {
 287                 struct spi_message *m;
 288                 struct spi_device *spi;
 289                 struct spi_transfer *t = NULL;
 290                 int par_override = 0;
 291                 int status = 0;
 292                 int cs_active = 0;
 293
 294                 m = container_of(orion_spi->msg_queue.next, struct spi_message,
 295                                  queue);
 296
 297                 list_del_init(&m->queue);
 298                 spin_unlock_irq(&orion_spi->lock);
 299
 300                 spi = m->spi;
 301
 302                 /* Load defaults */
 303                 status = orion_spi_setup_transfer(spi, NULL);
 304
 305                 if (status < 0)
 306                         goto msg_done;
 307
 308                 list_for_each_entry(t, &m->transfers, transfer_list) {
 309                         if (par_override || t->speed_hz || t->bits_per_word) {
 310                                 par_override = 1;
 311                                 status = orion_spi_setup_transfer(spi, t);
 312                                 if (status < 0)
 313                                         break;
 314                                 if (!t->speed_hz && !t->bits_per_word)
 315                                         par_override = 0;
 316                         }
 317
 318                         if (!cs_active) {
 319                                 orion_spi_set_cs(orion_spi, 1);
 320                                 cs_active = 1;
 321                         }
 322
 323                         if (t->len)
 324                                 m->actual_length +=
 325                                         orion_spi_write_read(spi, t);
 326
 327                         if (t->delay_usecs)
 328                                 udelay(t->delay_usecs);
 329
 330                         if (t->cs_change) {
 331                                 orion_spi_set_cs(orion_spi, 0);
 332                                 cs_active = 0;
 333                         }
 334                 }
 335
 336 msg_done:
 337                 if (cs_active)
 338                         orion_spi_set_cs(orion_spi, 0);
 339
 340                 m->status = status;
 341                 m->complete(m->context);
 342
 343                 spin_lock_irq(&orion_spi->lock);
 344         }
 345
 346         spin_unlock_irq(&orion_spi->lock);
 347 }
 348
 349 static int __init orion_spi_reset(struct orion_spi *orion_spi)
 350 {
 351         /* Verify that the CS is deasserted */
 352         orion_spi_set_cs(orion_spi, 0);
 353
 354         return 0;
 355 }
 356
 357 static int orion_spi_setup(struct spi_device *spi)
 358 {
 359         struct orion_spi *orion_spi;
 360
 361         orion_spi = spi_master_get_devdata(spi->master);
 362
 363         if ((spi->max_speed_hz == 0)
 364                         || (spi->max_speed_hz > orion_spi->max_speed))
 365                 spi->max_speed_hz = orion_spi->max_speed;
 366
 367         if (spi->max_speed_hz < orion_spi->min_speed) {
 368                 dev_err(&spi->dev, "setup: requested speed too low %d Hz\n",
 369                         spi->max_speed_hz);
 370                 return -EINVAL;
 371         }
 372
 373         /*
 374          * baudrate & width will be set orion_spi_setup_transfer
 375          */
 376         return 0;
 377 }
 378
 379 static int orion_spi_transfer(struct spi_device *spi, struct spi_message *m)
 380 {
 381         struct orion_spi *orion_spi;
 382         struct spi_transfer *t = NULL;
 383         unsigned long flags;
 384
 385         m->actual_length = 0;
 386         m->status = 0;
 387
 388         /* reject invalid messages and transfers */
 389         if (list_empty(&m->transfers) || !m->complete)
 390                 return -EINVAL;
 391
 392         orion_spi = spi_master_get_devdata(spi->master);
 393
 394         list_for_each_entry(t, &m->transfers, transfer_list) {
 395                 unsigned int bits_per_word = spi->bits_per_word;
 396
 397                 if (t->tx_buf == NULL && t->rx_buf == NULL && t->len) {
 398                         dev_err(&spi->dev,
 399                                 "message rejected : "
 400                                 "invalid transfer data buffers\n");
 401                         goto msg_rejected;
 402                 }
 403
 404                 if (t->bits_per_word)
 405                         bits_per_word = t->bits_per_word;
 406
 407                 if ((bits_per_word != 8) && (bits_per_word != 16)) {
 408                         dev_err(&spi->dev,
 409                                 "message rejected : "
 410                                 "invalid transfer bits_per_word (%d bits)\n",
 411                                 bits_per_word);
 412                         goto msg_rejected;
 413                 }
 414                 /*make sure buffer length is even when working in 16 bit mode*/
 415                 if ((t->bits_per_word == 16) && (t->len & 1)) {
 416                         dev_err(&spi->dev,
 417                                 "message rejected : "
 418                                 "odd data length (%d) while in 16 bit mode\n",
 419                                 t->len);
 420                         goto msg_rejected;
 421                 }
 422
 423                 if (t->speed_hz && t->speed_hz < orion_spi->min_speed) {
 424                         dev_err(&spi->dev,
 425                                 "message rejected : "
 426                                 "device min speed (%d Hz) exceeds "
 427                                 "required transfer speed (%d Hz)\n",
 428                                 orion_spi->min_speed, t->speed_hz);
 429                         goto msg_rejected;
 430                 }
 431         }
 432
 433
 434         spin_lock_irqsave(&orion_spi->lock, flags);
 435         list_add_tail(&m->queue, &orion_spi->msg_queue);
 436         queue_work(orion_spi_wq, &orion_spi->work);
 437         spin_unlock_irqrestore(&orion_spi->lock, flags);
 438
 439         return 0;
 440 msg_rejected:
 441         /* Message rejected and not queued */
 442         m->status = -EINVAL;
 443         if (m->complete)
 444                 m->complete(m->context);
 445         return -EINVAL;
 446 }
 447
 448 static int __init orion_spi_probe(struct platform_device *pdev)
 449 {
 450         struct spi_master *master;
 451         struct orion_spi *spi;
 452         struct resource *r;
 453         struct orion_spi_info *spi_info;
 454         unsigned long tclk_hz;
 455         int status = 0;
 456
 457         spi_info = pdev->dev.platform_data;
 458
 459         master = spi_alloc_master(&pdev->dev, sizeof *spi);
 460         if (master == NULL) {
 461                 dev_dbg(&pdev->dev, "master allocation failed\n");
 462                 return -ENOMEM;
 463         }
 464
 465         if (pdev->id != -1)
 466                 master->bus_num = pdev->id;
 467
 468         /* we support only mode 0, and no options */
 469         master->mode_bits = 0;
 470
 471         master->setup = orion_spi_setup;
 472         master->transfer = orion_spi_transfer;
 473         master->num_chipselect = ORION_NUM_CHIPSELECTS;
 474
 475         dev_set_drvdata(&pdev->dev, master);
 476
 477         spi = spi_master_get_devdata(master);
 478         spi->master = master;
 479         spi->spi_info = spi_info;
 480
 481         spi->clk = clk_get(&pdev->dev, NULL);
 482         if (IS_ERR(spi->clk)) {
 483                 status = PTR_ERR(spi->clk);
 484                 goto out;
 485         }
 486
 487         clk_prepare(spi->clk);
 488         clk_enable(spi->clk);
 489         tclk_hz = clk_get_rate(spi->clk);
 490         spi->max_speed = DIV_ROUND_UP(tclk_hz, 4);
 491         spi->min_speed = DIV_ROUND_UP(tclk_hz, 30);
 492
 493         r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 494         if (r == NULL) {
 495                 status = -ENODEV;
 496                 goto out_rel_clk;
 497         }
 498
 499         if (!request_mem_region(r->start, resource_size(r),
 500                                 dev_name(&pdev->dev))) {
 501                 status = -EBUSY;
 502                 goto out_rel_clk;
 503         }
 504         spi->base = ioremap(r->start, SZ_1K);
 505
 506         INIT_WORK(&spi->work, orion_spi_work);
 507
 508         spin_lock_init(&spi->lock);
 509         INIT_LIST_HEAD(&spi->msg_queue);
 510
 511         if (orion_spi_reset(spi) < 0)
 512                 goto out_rel_mem;
 513
 514         status = spi_register_master(master);
 515         if (status < 0)
 516                 goto out_rel_mem;
 517
 518         return status;
 519
 520 out_rel_mem:
 521         release_mem_region(r->start, resource_size(r));
 522 out_rel_clk:
 523         clk_disable_unprepare(spi->clk);
 524         clk_put(spi->clk);
 525 out:
 526         spi_master_put(master);
 527         return status;
 528 }
 529
 530
 531 static int __exit orion_spi_remove(struct platform_device *pdev)
 532 {
 533         struct spi_master *master;
 534         struct orion_spi *spi;
 535         struct resource *r;
 536
 537         master = dev_get_drvdata(&pdev->dev);
 538         spi = spi_master_get_devdata(master);
 539
 540         cancel_work_sync(&spi->work);
 541
 542         clk_disable_unprepare(spi->clk);
 543         clk_put(spi->clk);
 544
 545         r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 546         release_mem_region(r->start, resource_size(r));
 547
 548         spi_unregister_master(master);
 549
 550         return 0;
 551 }
 552
 553 MODULE_ALIAS("platform:" DRIVER_NAME);
 554
 555 static struct platform_driver orion_spi_driver = {
 556         .driver = {
 557                 .name   = DRIVER_NAME,
 558                 .owner  = THIS_MODULE,
 559         },
 560         .remove         = __exit_p(orion_spi_remove),
 561 };
 562
 563 static int __init orion_spi_init(void)
 564 {
 565         orion_spi_wq = create_singlethread_workqueue(
 566                                 orion_spi_driver.driver.name);
 567         if (orion_spi_wq == NULL)
 568                 return -ENOMEM;
 569
 570         return platform_driver_probe(&orion_spi_driver, orion_spi_probe);
 571 }
 572 module_init(orion_spi_init);
 573
 574 static void __exit orion_spi_exit(void)
 575 {
 576         flush_workqueue(orion_spi_wq);
 577         platform_driver_unregister(&orion_spi_driver);
 578
 579         destroy_workqueue(orion_spi_wq);
 580 }
 581 module_exit(orion_spi_exit);
 582
 583 MODULE_DESCRIPTION("Orion SPI driver");
 584 MODULE_AUTHOR("Shadi Ammouri <shadi@marvell.com>");
 585 MODULE_LICENSE("GPL");