drivers/spi/spi-dw.c

   1 /*
   2  * Designware SPI core controller driver (refer pxa2xx_spi.c)
   3  *
   4  * Copyright (c) 2009, Intel Corporation.
   5  *
   6  * This program is free software; you can redistribute it and/or modify it
   7  * under the terms and conditions of the GNU General Public License,
   8  * version 2, as published by the Free Software Foundation.
   9  *
  10  * This program is distributed in the hope it will be useful, but WITHOUT
  11  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  12  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  13  * more details.
  14  *
  15  * You should have received a copy of the GNU General Public License along with
  16  * this program; if not, write to the Free Software Foundation, Inc.,
  17  * 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
  18  */
  19
  20 #include <linux/dma-mapping.h>
  21 #include <linux/interrupt.h>
  22 #include <linux/module.h>
  23 #include <linux/highmem.h>
  24 #include <linux/delay.h>
  25 #include <linux/slab.h>
  26 #include <linux/spi/spi.h>
  27 #include <linux/gpio.h>
  28
  29 #include "spi-dw.h"
  30
  31 #ifdef CONFIG_DEBUG_FS
  32 #include <linux/debugfs.h>
  33 #endif
  34
  35 #define START_STATE     ((void *)0)
  36 #define RUNNING_STATE   ((void *)1)
  37 #define DONE_STATE      ((void *)2)
  38 #define ERROR_STATE     ((void *)-1)
  39
  40 /* Slave spi_dev related */
  41 struct chip_data {
  42         u16 cr0;
  43         u8 cs;                  /* chip select pin */
  44         u8 n_bytes;             /* current is a 1/2/4 byte op */
  45         u8 tmode;               /* TR/TO/RO/EEPROM */
  46         u8 type;                /* SPI/SSP/MicroWire */
  47
  48         u8 poll_mode;           /* 1 means use poll mode */
  49
  50         u32 dma_width;
  51         u32 rx_threshold;
  52         u32 tx_threshold;
  53         u8 enable_dma;
  54         u8 bits_per_word;
  55         u16 clk_div;            /* baud rate divider */
  56         u32 speed_hz;           /* baud rate */
  57         void (*cs_control)(u32 command);
  58 };
  59
  60 #ifdef CONFIG_DEBUG_FS
  61 #define SPI_REGS_BUFSIZE        1024
  62 static ssize_t  spi_show_regs(struct file *file, char __user *user_buf,
  63                                 size_t count, loff_t *ppos)
  64 {
  65         struct dw_spi *dws;
  66         char *buf;
  67         u32 len = 0;
  68         ssize_t ret;
  69
  70         dws = file->private_data;
  71
  72         buf = kzalloc(SPI_REGS_BUFSIZE, GFP_KERNEL);
  73         if (!buf)
  74                 return 0;
  75
  76         len += snprintf(buf + len, SPI_REGS_BUFSIZE - len,
  77                         "MRST SPI0 registers:\n");
  78         len += snprintf(buf + len, SPI_REGS_BUFSIZE - len,
  79                         "=================================\n");
  80         len += snprintf(buf + len, SPI_REGS_BUFSIZE - len,
  81                         "CTRL0: \t\t0x%08x\n", dw_readl(dws, DW_SPI_CTRL0));
  82         len += snprintf(buf + len, SPI_REGS_BUFSIZE - len,
  83                         "CTRL1: \t\t0x%08x\n", dw_readl(dws, DW_SPI_CTRL1));
  84         len += snprintf(buf + len, SPI_REGS_BUFSIZE - len,
  85                         "SSIENR: \t0x%08x\n", dw_readl(dws, DW_SPI_SSIENR));
  86         len += snprintf(buf + len, SPI_REGS_BUFSIZE - len,
  87                         "SER: \t\t0x%08x\n", dw_readl(dws, DW_SPI_SER));
  88         len += snprintf(buf + len, SPI_REGS_BUFSIZE - len,
  89                         "BAUDR: \t\t0x%08x\n", dw_readl(dws, DW_SPI_BAUDR));
  90         len += snprintf(buf + len, SPI_REGS_BUFSIZE - len,
  91                         "TXFTLR: \t0x%08x\n", dw_readl(dws, DW_SPI_TXFLTR));
  92         len += snprintf(buf + len, SPI_REGS_BUFSIZE - len,
  93                         "RXFTLR: \t0x%08x\n", dw_readl(dws, DW_SPI_RXFLTR));
  94         len += snprintf(buf + len, SPI_REGS_BUFSIZE - len,
  95                         "TXFLR: \t\t0x%08x\n", dw_readl(dws, DW_SPI_TXFLR));
  96         len += snprintf(buf + len, SPI_REGS_BUFSIZE - len,
  97                         "RXFLR: \t\t0x%08x\n", dw_readl(dws, DW_SPI_RXFLR));
  98         len += snprintf(buf + len, SPI_REGS_BUFSIZE - len,
  99                         "SR: \t\t0x%08x\n", dw_readl(dws, DW_SPI_SR));
 100         len += snprintf(buf + len, SPI_REGS_BUFSIZE - len,
 101                         "IMR: \t\t0x%08x\n", dw_readl(dws, DW_SPI_IMR));
 102         len += snprintf(buf + len, SPI_REGS_BUFSIZE - len,
 103                         "ISR: \t\t0x%08x\n", dw_readl(dws, DW_SPI_ISR));
 104         len += snprintf(buf + len, SPI_REGS_BUFSIZE - len,
 105                         "DMACR: \t\t0x%08x\n", dw_readl(dws, DW_SPI_DMACR));
 106         len += snprintf(buf + len, SPI_REGS_BUFSIZE - len,
 107                         "DMATDLR: \t0x%08x\n", dw_readl(dws, DW_SPI_DMATDLR));
 108         len += snprintf(buf + len, SPI_REGS_BUFSIZE - len,
 109                         "DMARDLR: \t0x%08x\n", dw_readl(dws, DW_SPI_DMARDLR));
 110         len += snprintf(buf + len, SPI_REGS_BUFSIZE - len,
 111                         "=================================\n");
 112
 113         ret =  simple_read_from_buffer(user_buf, count, ppos, buf, len);
 114         kfree(buf);
 115         return ret;
 116 }
 117
 118 static const struct file_operations mrst_spi_regs_ops = {
 119         .owner          = THIS_MODULE,
 120         .open           = simple_open,
 121         .read           = spi_show_regs,
 122         .llseek         = default_llseek,
 123 };
 124
 125 static int mrst_spi_debugfs_init(struct dw_spi *dws)
 126 {
 127         dws->debugfs = debugfs_create_dir("mrst_spi", NULL);
 128         if (!dws->debugfs)
 129                 return -ENOMEM;
 130
 131         debugfs_create_file("registers", S_IFREG | S_IRUGO,
 132                 dws->debugfs, (void *)dws, &mrst_spi_regs_ops);
 133         return 0;
 134 }
 135
 136 static void mrst_spi_debugfs_remove(struct dw_spi *dws)
 137 {
 138         if (dws->debugfs)
 139                 debugfs_remove_recursive(dws->debugfs);
 140 }
 141
 142 #else
 143 static inline int mrst_spi_debugfs_init(struct dw_spi *dws)
 144 {
 145         return 0;
 146 }
 147
 148 static inline void mrst_spi_debugfs_remove(struct dw_spi *dws)
 149 {
 150 }
 151 #endif /* CONFIG_DEBUG_FS */
 152
 153 /* Return the max entries we can fill into tx fifo */
 154 static inline u32 tx_max(struct dw_spi *dws)
 155 {
 156         u32 tx_left, tx_room, rxtx_gap;
 157
 158         tx_left = (dws->tx_end - dws->tx) / dws->n_bytes;
 159         tx_room = dws->fifo_len - dw_readw(dws, DW_SPI_TXFLR);
 160
 161         /*
 162          * Another concern is about the tx/rx mismatch, we
 163          * though to use (dws->fifo_len - rxflr - txflr) as
 164          * one maximum value for tx, but it doesn't cover the
 165          * data which is out of tx/rx fifo and inside the
 166          * shift registers. So a control from sw point of
 167          * view is taken.
 168          */
 169         rxtx_gap =  ((dws->rx_end - dws->rx) - (dws->tx_end - dws->tx))
 170                         / dws->n_bytes;
 171
 172         return min3(tx_left, tx_room, (u32) (dws->fifo_len - rxtx_gap));
 173 }
 174
 175 /* Return the max entries we should read out of rx fifo */
 176 static inline u32 rx_max(struct dw_spi *dws)
 177 {
 178         u32 rx_left = (dws->rx_end - dws->rx) / dws->n_bytes;
 179
 180         return min(rx_left, (u32)dw_readw(dws, DW_SPI_RXFLR));
 181 }
 182
 183 static void dw_writer(struct dw_spi *dws)
 184 {
 185         u32 max = tx_max(dws);
 186         u16 txw = 0;
 187
 188         while (max--) {
 189                 /* Set the tx word if the transfer's original "tx" is not null */
 190                 if (dws->tx_end - dws->len) {
 191                         if (dws->n_bytes == 1)
 192                                 txw = *(u8 *)(dws->tx);
 193                         else
 194                                 txw = *(u16 *)(dws->tx);
 195                 }
 196                 dw_writew(dws, DW_SPI_DR, txw);
 197                 dws->tx += dws->n_bytes;
 198         }
 199 }
 200
 201 static void dw_reader(struct dw_spi *dws)
 202 {
 203         u32 max = rx_max(dws);
 204         u16 rxw;
 205
 206         while (max--) {
 207                 rxw = dw_readw(dws, DW_SPI_DR);
 208                 /* Care rx only if the transfer's original "rx" is not null */
 209                 if (dws->rx_end - dws->len) {
 210                         if (dws->n_bytes == 1)
 211                                 *(u8 *)(dws->rx) = rxw;
 212                         else
 213                                 *(u16 *)(dws->rx) = rxw;
 214                 }
 215                 dws->rx += dws->n_bytes;
 216         }
 217 }
 218
 219 static void *next_transfer(struct dw_spi *dws)
 220 {
 221         struct spi_message *msg = dws->cur_msg;
 222         struct spi_transfer *trans = dws->cur_transfer;
 223
 224         /* Move to next transfer */
 225         if (trans->transfer_list.next != &msg->transfers) {
 226                 dws->cur_transfer =
 227                         list_entry(trans->transfer_list.next,
 228                                         struct spi_transfer,
 229                                         transfer_list);
 230                 return RUNNING_STATE;
 231         } else
 232                 return DONE_STATE;
 233 }
 234
 235 /*
 236  * Note: first step is the protocol driver prepares
 237  * a dma-capable memory, and this func just need translate
 238  * the virt addr to physical
 239  */
 240 static int map_dma_buffers(struct dw_spi *dws)
 241 {
 242         if (!dws->cur_msg->is_dma_mapped
 243                 || !dws->dma_inited
 244                 || !dws->cur_chip->enable_dma
 245                 || !dws->dma_ops)
 246                 return 0;
 247
 248         if (dws->cur_transfer->tx_dma)
 249                 dws->tx_dma = dws->cur_transfer->tx_dma;
 250
 251         if (dws->cur_transfer->rx_dma)
 252                 dws->rx_dma = dws->cur_transfer->rx_dma;
 253
 254         return 1;
 255 }
 256
 257 /* Caller already set message->status; dma and pio irqs are blocked */
 258 static void giveback(struct dw_spi *dws)
 259 {
 260         struct spi_transfer *last_transfer;
 261         struct spi_message *msg;
 262
 263         msg = dws->cur_msg;
 264         dws->cur_msg = NULL;
 265         dws->cur_transfer = NULL;
 266         dws->prev_chip = dws->cur_chip;
 267         dws->cur_chip = NULL;
 268         dws->dma_mapped = 0;
 269
 270         last_transfer = list_last_entry(&msg->transfers, struct spi_transfer,
 271                                         transfer_list);
 272
 273         if (!last_transfer->cs_change)
 274                 spi_chip_sel(dws, dws->cur_msg->spi, 0);
 275
 276         spi_finalize_current_message(dws->master);
 277 }
 278
 279 static void int_error_stop(struct dw_spi *dws, const char *msg)
 280 {
 281         /* Stop the hw */
 282         spi_enable_chip(dws, 0);
 283
 284         dev_err(&dws->master->dev, "%s\n", msg);
 285         dws->cur_msg->state = ERROR_STATE;
 286         tasklet_schedule(&dws->pump_transfers);
 287 }
 288
 289 void dw_spi_xfer_done(struct dw_spi *dws)
 290 {
 291         /* Update total byte transferred return count actual bytes read */
 292         dws->cur_msg->actual_length += dws->len;
 293
 294         /* Move to next transfer */
 295         dws->cur_msg->state = next_transfer(dws);
 296
 297         /* Handle end of message */
 298         if (dws->cur_msg->state == DONE_STATE) {
 299                 dws->cur_msg->status = 0;
 300                 giveback(dws);
 301         } else
 302                 tasklet_schedule(&dws->pump_transfers);
 303 }
 304 EXPORT_SYMBOL_GPL(dw_spi_xfer_done);
 305
 306 static irqreturn_t interrupt_transfer(struct dw_spi *dws)
 307 {
 308         u16 irq_status = dw_readw(dws, DW_SPI_ISR);
 309
 310         /* Error handling */
 311         if (irq_status & (SPI_INT_TXOI | SPI_INT_RXOI | SPI_INT_RXUI)) {
 312                 dw_readw(dws, DW_SPI_TXOICR);
 313                 dw_readw(dws, DW_SPI_RXOICR);
 314                 dw_readw(dws, DW_SPI_RXUICR);
 315                 int_error_stop(dws, "interrupt_transfer: fifo overrun/underrun");
 316                 return IRQ_HANDLED;
 317         }
 318
 319         dw_reader(dws);
 320         if (dws->rx_end == dws->rx) {
 321                 spi_mask_intr(dws, SPI_INT_TXEI);
 322                 dw_spi_xfer_done(dws);
 323                 return IRQ_HANDLED;
 324         }
 325         if (irq_status & SPI_INT_TXEI) {
 326                 spi_mask_intr(dws, SPI_INT_TXEI);
 327                 dw_writer(dws);
 328                 /* Enable TX irq always, it will be disabled when RX finished */
 329                 spi_umask_intr(dws, SPI_INT_TXEI);
 330         }
 331
 332         return IRQ_HANDLED;
 333 }
 334
 335 static irqreturn_t dw_spi_irq(int irq, void *dev_id)
 336 {
 337         struct dw_spi *dws = dev_id;
 338         u16 irq_status = dw_readw(dws, DW_SPI_ISR) & 0x3f;
 339
 340         if (!irq_status)
 341                 return IRQ_NONE;
 342
 343         if (!dws->cur_msg) {
 344                 spi_mask_intr(dws, SPI_INT_TXEI);
 345                 return IRQ_HANDLED;
 346         }
 347
 348         return dws->transfer_handler(dws);
 349 }
 350
 351 /* Must be called inside pump_transfers() */
 352 static void poll_transfer(struct dw_spi *dws)
 353 {
 354         do {
 355                 dw_writer(dws);
 356                 dw_reader(dws);
 357                 cpu_relax();
 358         } while (dws->rx_end > dws->rx);
 359
 360         dw_spi_xfer_done(dws);
 361 }
 362
 363 static void pump_transfers(unsigned long data)
 364 {
 365         struct dw_spi *dws = (struct dw_spi *)data;
 366         struct spi_message *message = NULL;
 367         struct spi_transfer *transfer = NULL;
 368         struct spi_transfer *previous = NULL;
 369         struct spi_device *spi = NULL;
 370         struct chip_data *chip = NULL;
 371         u8 bits = 0;
 372         u8 imask = 0;
 373         u8 cs_change = 0;
 374         u16 txint_level = 0;
 375         u16 clk_div = 0;
 376         u32 speed = 0;
 377         u32 cr0 = 0;
 378
 379         /* Get current state information */
 380         message = dws->cur_msg;
 381         transfer = dws->cur_transfer;
 382         chip = dws->cur_chip;
 383         spi = message->spi;
 384
 385         if (unlikely(!chip->clk_div))
 386                 chip->clk_div = dws->max_freq / chip->speed_hz;
 387
 388         if (message->state == ERROR_STATE) {
 389                 message->status = -EIO;
 390                 goto early_exit;
 391         }
 392
 393         /* Handle end of message */
 394         if (message->state == DONE_STATE) {
 395                 message->status = 0;
 396                 goto early_exit;
 397         }
 398
 399         /* Delay if requested at end of transfer*/
 400         if (message->state == RUNNING_STATE) {
 401                 previous = list_entry(transfer->transfer_list.prev,
 402                                         struct spi_transfer,
 403                                         transfer_list);
 404                 if (previous->delay_usecs)
 405                         udelay(previous->delay_usecs);
 406         }
 407
 408         dws->n_bytes = chip->n_bytes;
 409         dws->dma_width = chip->dma_width;
 410         dws->cs_control = chip->cs_control;
 411
 412         dws->rx_dma = transfer->rx_dma;
 413         dws->tx_dma = transfer->tx_dma;
 414         dws->tx = (void *)transfer->tx_buf;
 415         dws->tx_end = dws->tx + transfer->len;
 416         dws->rx = transfer->rx_buf;
 417         dws->rx_end = dws->rx + transfer->len;
 418         dws->len = dws->cur_transfer->len;
 419         if (chip != dws->prev_chip)
 420                 cs_change = 1;
 421
 422         cr0 = chip->cr0;
 423
 424         /* Handle per transfer options for bpw and speed */
 425         if (transfer->speed_hz) {
 426                 speed = chip->speed_hz;
 427
 428                 if (transfer->speed_hz != speed) {
 429                         speed = transfer->speed_hz;
 430
 431                         /* clk_div doesn't support odd number */
 432                         clk_div = dws->max_freq / speed;
 433                         clk_div = (clk_div + 1) & 0xfffe;
 434
 435                         chip->speed_hz = speed;
 436                         chip->clk_div = clk_div;
 437                 }
 438         }
 439         if (transfer->bits_per_word) {
 440                 bits = transfer->bits_per_word;
 441                 dws->n_bytes = dws->dma_width = bits >> 3;
 442                 cr0 = (bits - 1)
 443                         | (chip->type << SPI_FRF_OFFSET)
 444                         | (spi->mode << SPI_MODE_OFFSET)
 445                         | (chip->tmode << SPI_TMOD_OFFSET);
 446         }
 447         message->state = RUNNING_STATE;
 448
 449         /*
 450          * Adjust transfer mode if necessary. Requires platform dependent
 451          * chipselect mechanism.
 452          */
 453         if (dws->cs_control) {
 454                 if (dws->rx && dws->tx)
 455                         chip->tmode = SPI_TMOD_TR;
 456                 else if (dws->rx)
 457                         chip->tmode = SPI_TMOD_RO;
 458                 else
 459                         chip->tmode = SPI_TMOD_TO;
 460
 461                 cr0 &= ~SPI_TMOD_MASK;
 462                 cr0 |= (chip->tmode << SPI_TMOD_OFFSET);
 463         }
 464
 465         /* Check if current transfer is a DMA transaction */
 466         dws->dma_mapped = map_dma_buffers(dws);
 467
 468         /*
 469          * Interrupt mode
 470          * we only need set the TXEI IRQ, as TX/RX always happen syncronizely
 471          */
 472         if (!dws->dma_mapped && !chip->poll_mode) {
 473                 int templen = dws->len / dws->n_bytes;
 474                 txint_level = dws->fifo_len / 2;
 475                 txint_level = (templen > txint_level) ? txint_level : templen;
 476
 477                 imask |= SPI_INT_TXEI | SPI_INT_TXOI | SPI_INT_RXUI | SPI_INT_RXOI;
 478                 dws->transfer_handler = interrupt_transfer;
 479         }
 480
 481         /*
 482          * Reprogram registers only if
 483          *      1. chip select changes
 484          *      2. clk_div is changed
 485          *      3. control value changes
 486          */
 487         if (dw_readw(dws, DW_SPI_CTRL0) != cr0 || cs_change || clk_div || imask) {
 488                 spi_enable_chip(dws, 0);
 489
 490                 if (dw_readw(dws, DW_SPI_CTRL0) != cr0)
 491                         dw_writew(dws, DW_SPI_CTRL0, cr0);
 492
 493                 spi_set_clk(dws, clk_div ? clk_div : chip->clk_div);
 494                 spi_chip_sel(dws, spi, 1);
 495
 496                 /* Set the interrupt mask, for poll mode just disable all int */
 497                 spi_mask_intr(dws, 0xff);
 498                 if (imask)
 499                         spi_umask_intr(dws, imask);
 500                 if (txint_level)
 501                         dw_writew(dws, DW_SPI_TXFLTR, txint_level);
 502
 503                 spi_enable_chip(dws, 1);
 504                 if (cs_change)
 505                         dws->prev_chip = chip;
 506         }
 507
 508         if (dws->dma_mapped)
 509                 dws->dma_ops->dma_transfer(dws, cs_change);
 510
 511         if (chip->poll_mode)
 512                 poll_transfer(dws);
 513
 514         return;
 515
 516 early_exit:
 517         giveback(dws);
 518         return;
 519 }
 520
 521 static int dw_spi_transfer_one_message(struct spi_master *master,
 522                 struct spi_message *msg)
 523 {
 524         struct dw_spi *dws = spi_master_get_devdata(master);
 525
 526         dws->cur_msg = msg;
 527         /* Initial message state*/
 528         dws->cur_msg->state = START_STATE;
 529         dws->cur_transfer = list_entry(dws->cur_msg->transfers.next,
 530                                                 struct spi_transfer,
 531                                                 transfer_list);
 532         dws->cur_chip = spi_get_ctldata(dws->cur_msg->spi);
 533
 534         /* Launch transfers */
 535         tasklet_schedule(&dws->pump_transfers);
 536
 537         return 0;
 538 }
 539
 540 /* This may be called twice for each spi dev */
 541 static int dw_spi_setup(struct spi_device *spi)
 542 {
 543         struct dw_spi_chip *chip_info = NULL;
 544         struct chip_data *chip;
 545         int ret;
 546
 547         /* Only alloc on first setup */
 548         chip = spi_get_ctldata(spi);
 549         if (!chip) {
 550                 chip = devm_kzalloc(&spi->dev, sizeof(struct chip_data),
 551                                 GFP_KERNEL);
 552                 if (!chip)
 553                         return -ENOMEM;
 554                 spi_set_ctldata(spi, chip);
 555         }
 556
 557         /*
 558          * Protocol drivers may change the chip settings, so...
 559          * if chip_info exists, use it
 560          */
 561         chip_info = spi->controller_data;
 562
 563         /* chip_info doesn't always exist */
 564         if (chip_info) {
 565                 if (chip_info->cs_control)
 566                         chip->cs_control = chip_info->cs_control;
 567
 568                 chip->poll_mode = chip_info->poll_mode;
 569                 chip->type = chip_info->type;
 570
 571                 chip->rx_threshold = 0;
 572                 chip->tx_threshold = 0;
 573
 574                 chip->enable_dma = chip_info->enable_dma;
 575         }
 576
 577         if (spi->bits_per_word == 8) {
 578                 chip->n_bytes = 1;
 579                 chip->dma_width = 1;
 580         } else if (spi->bits_per_word == 16) {
 581                 chip->n_bytes = 2;
 582                 chip->dma_width = 2;
 583         }
 584         chip->bits_per_word = spi->bits_per_word;
 585
 586         if (!spi->max_speed_hz) {
 587                 dev_err(&spi->dev, "No max speed HZ parameter\n");
 588                 return -EINVAL;
 589         }
 590         chip->speed_hz = spi->max_speed_hz;
 591
 592         chip->tmode = 0; /* Tx & Rx */
 593         /* Default SPI mode is SCPOL = 0, SCPH = 0 */
 594         chip->cr0 = (chip->bits_per_word - 1)
 595                         | (chip->type << SPI_FRF_OFFSET)
 596                         | (spi->mode  << SPI_MODE_OFFSET)
 597                         | (chip->tmode << SPI_TMOD_OFFSET);
 598
 599         if (gpio_is_valid(spi->cs_gpio)) {
 600                 ret = gpio_direction_output(spi->cs_gpio,
 601                                 !(spi->mode & SPI_CS_HIGH));
 602                 if (ret)
 603                         return ret;
 604         }
 605
 606         return 0;
 607 }
 608
 609 /* Restart the controller, disable all interrupts, clean rx fifo */
 610 static void spi_hw_init(struct dw_spi *dws)
 611 {
 612         spi_enable_chip(dws, 0);
 613         spi_mask_intr(dws, 0xff);
 614         spi_enable_chip(dws, 1);
 615
 616         /*
 617          * Try to detect the FIFO depth if not set by interface driver,
 618          * the depth could be from 2 to 256 from HW spec
 619          */
 620         if (!dws->fifo_len) {
 621                 u32 fifo;
 622                 for (fifo = 2; fifo <= 257; fifo++) {
 623                         dw_writew(dws, DW_SPI_TXFLTR, fifo);
 624                         if (fifo != dw_readw(dws, DW_SPI_TXFLTR))
 625                                 break;
 626                 }
 627
 628                 dws->fifo_len = (fifo == 257) ? 0 : fifo;
 629                 dw_writew(dws, DW_SPI_TXFLTR, 0);
 630         }
 631 }
 632
 633 int dw_spi_add_host(struct device *dev, struct dw_spi *dws)
 634 {
 635         struct spi_master *master;
 636         int ret;
 637
 638         BUG_ON(dws == NULL);
 639
 640         master = spi_alloc_master(dev, 0);
 641         if (!master)
 642                 return -ENOMEM;
 643
 644         dws->master = master;
 645         dws->type = SSI_MOTO_SPI;
 646         dws->prev_chip = NULL;
 647         dws->dma_inited = 0;
 648         dws->dma_addr = (dma_addr_t)(dws->paddr + 0x60);
 649         snprintf(dws->name, sizeof(dws->name), "dw_spi%d",
 650                         dws->bus_num);
 651
 652         ret = devm_request_irq(dev, dws->irq, dw_spi_irq, IRQF_SHARED,
 653                         dws->name, dws);
 654         if (ret < 0) {
 655                 dev_err(&master->dev, "can not get IRQ\n");
 656                 goto err_free_master;
 657         }
 658
 659         master->mode_bits = SPI_CPOL | SPI_CPHA;
 660         master->bits_per_word_mask = SPI_BPW_MASK(8) | SPI_BPW_MASK(16);
 661         master->bus_num = dws->bus_num;
 662         master->num_chipselect = dws->num_cs;
 663         master->setup = dw_spi_setup;
 664         master->transfer_one_message = dw_spi_transfer_one_message;
 665         master->max_speed_hz = dws->max_freq;
 666
 667         /* Basic HW init */
 668         spi_hw_init(dws);
 669
 670         if (dws->dma_ops && dws->dma_ops->dma_init) {
 671                 ret = dws->dma_ops->dma_init(dws);
 672                 if (ret) {
 673                         dev_warn(&master->dev, "DMA init failed\n");
 674                         dws->dma_inited = 0;
 675                 }
 676         }
 677
 678         tasklet_init(&dws->pump_transfers, pump_transfers, (unsigned long)dws);
 679
 680         spi_master_set_devdata(master, dws);
 681         ret = devm_spi_register_master(dev, master);
 682         if (ret) {
 683                 dev_err(&master->dev, "problem registering spi master\n");
 684                 goto err_dma_exit;
 685         }
 686
 687         mrst_spi_debugfs_init(dws);
 688         return 0;
 689
 690 err_dma_exit:
 691         if (dws->dma_ops && dws->dma_ops->dma_exit)
 692                 dws->dma_ops->dma_exit(dws);
 693         spi_enable_chip(dws, 0);
 694 err_free_master:
 695         spi_master_put(master);
 696         return ret;
 697 }
 698 EXPORT_SYMBOL_GPL(dw_spi_add_host);
 699
 700 void dw_spi_remove_host(struct dw_spi *dws)
 701 {
 702         if (!dws)
 703                 return;
 704         mrst_spi_debugfs_remove(dws);
 705
 706         if (dws->dma_ops && dws->dma_ops->dma_exit)
 707                 dws->dma_ops->dma_exit(dws);
 708         spi_enable_chip(dws, 0);
 709         /* Disable clk */
 710         spi_set_clk(dws, 0);
 711 }
 712 EXPORT_SYMBOL_GPL(dw_spi_remove_host);
 713
 714 int dw_spi_suspend_host(struct dw_spi *dws)
 715 {
 716         int ret = 0;
 717
 718         ret = spi_master_suspend(dws->master);
 719         if (ret)
 720                 return ret;
 721         spi_enable_chip(dws, 0);
 722         spi_set_clk(dws, 0);
 723         return ret;
 724 }
 725 EXPORT_SYMBOL_GPL(dw_spi_suspend_host);
 726
 727 int dw_spi_resume_host(struct dw_spi *dws)
 728 {
 729         int ret;
 730
 731         spi_hw_init(dws);
 732         ret = spi_master_resume(dws->master);
 733         if (ret)
 734                 dev_err(&dws->master->dev, "fail to start queue (%d)\n", ret);
 735         return ret;
 736 }
 737 EXPORT_SYMBOL_GPL(dw_spi_resume_host);
 738
 739 MODULE_AUTHOR("Feng Tang <feng.tang@intel.com>");
 740 MODULE_DESCRIPTION("Driver for DesignWare SPI controller core");
 741 MODULE_LICENSE("GPL v2");