drivers/spi/spi-tegra20-sflash.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * SPI driver for Nvidia's Tegra20 Serial Flash Controller.
   4  *
   5  * Copyright (c) 2012, NVIDIA CORPORATION.  All rights reserved.
   6  *
   7  * Author: Laxman Dewangan <ldewangan@nvidia.com>
   8  */
   9
  10 #include <linux/clk.h>
  11 #include <linux/completion.h>
  12 #include <linux/delay.h>
  13 #include <linux/err.h>
  14 #include <linux/interrupt.h>
  15 #include <linux/io.h>
  16 #include <linux/kernel.h>
  17 #include <linux/kthread.h>
  18 #include <linux/module.h>
  19 #include <linux/platform_device.h>
  20 #include <linux/pm_runtime.h>
  21 #include <linux/of.h>
  22 #include <linux/of_device.h>
  23 #include <linux/reset.h>
  24 #include <linux/spi/spi.h>
  25
  26 #define SPI_COMMAND                             0x000
  27 #define SPI_GO                                  BIT(30)
  28 #define SPI_M_S                                 BIT(28)
  29 #define SPI_ACTIVE_SCLK_MASK                    (0x3 << 26)
  30 #define SPI_ACTIVE_SCLK_DRIVE_LOW               (0 << 26)
  31 #define SPI_ACTIVE_SCLK_DRIVE_HIGH              (1 << 26)
  32 #define SPI_ACTIVE_SCLK_PULL_LOW                (2 << 26)
  33 #define SPI_ACTIVE_SCLK_PULL_HIGH               (3 << 26)
  34
  35 #define SPI_CK_SDA_FALLING                      (1 << 21)
  36 #define SPI_CK_SDA_RISING                       (0 << 21)
  37 #define SPI_CK_SDA_MASK                         (1 << 21)
  38 #define SPI_ACTIVE_SDA                          (0x3 << 18)
  39 #define SPI_ACTIVE_SDA_DRIVE_LOW                (0 << 18)
  40 #define SPI_ACTIVE_SDA_DRIVE_HIGH               (1 << 18)
  41 #define SPI_ACTIVE_SDA_PULL_LOW                 (2 << 18)
  42 #define SPI_ACTIVE_SDA_PULL_HIGH                (3 << 18)
  43
  44 #define SPI_CS_POL_INVERT                       BIT(16)
  45 #define SPI_TX_EN                               BIT(15)
  46 #define SPI_RX_EN                               BIT(14)
  47 #define SPI_CS_VAL_HIGH                         BIT(13)
  48 #define SPI_CS_VAL_LOW                          0x0
  49 #define SPI_CS_SW                               BIT(12)
  50 #define SPI_CS_HW                               0x0
  51 #define SPI_CS_DELAY_MASK                       (7 << 9)
  52 #define SPI_CS3_EN                              BIT(8)
  53 #define SPI_CS2_EN                              BIT(7)
  54 #define SPI_CS1_EN                              BIT(6)
  55 #define SPI_CS0_EN                              BIT(5)
  56
  57 #define SPI_CS_MASK                     (SPI_CS3_EN | SPI_CS2_EN |      \
  58                                         SPI_CS1_EN | SPI_CS0_EN)
  59 #define SPI_BIT_LENGTH(x)               (((x) & 0x1f) << 0)
  60
  61 #define SPI_MODES                       (SPI_ACTIVE_SCLK_MASK | SPI_CK_SDA_MASK)
  62
  63 #define SPI_STATUS                      0x004
  64 #define SPI_BSY                         BIT(31)
  65 #define SPI_RDY                         BIT(30)
  66 #define SPI_TXF_FLUSH                   BIT(29)
  67 #define SPI_RXF_FLUSH                   BIT(28)
  68 #define SPI_RX_UNF                      BIT(27)
  69 #define SPI_TX_OVF                      BIT(26)
  70 #define SPI_RXF_EMPTY                   BIT(25)
  71 #define SPI_RXF_FULL                    BIT(24)
  72 #define SPI_TXF_EMPTY                   BIT(23)
  73 #define SPI_TXF_FULL                    BIT(22)
  74 #define SPI_BLK_CNT(count)              (((count) & 0xffff) + 1)
  75
  76 #define SPI_FIFO_ERROR                  (SPI_RX_UNF | SPI_TX_OVF)
  77 #define SPI_FIFO_EMPTY                  (SPI_TX_EMPTY | SPI_RX_EMPTY)
  78
  79 #define SPI_RX_CMP                      0x8
  80 #define SPI_DMA_CTL                     0x0C
  81 #define SPI_DMA_EN                      BIT(31)
  82 #define SPI_IE_RXC                      BIT(27)
  83 #define SPI_IE_TXC                      BIT(26)
  84 #define SPI_PACKED                      BIT(20)
  85 #define SPI_RX_TRIG_MASK                (0x3 << 18)
  86 #define SPI_RX_TRIG_1W                  (0x0 << 18)
  87 #define SPI_RX_TRIG_4W                  (0x1 << 18)
  88 #define SPI_TX_TRIG_MASK                (0x3 << 16)
  89 #define SPI_TX_TRIG_1W                  (0x0 << 16)
  90 #define SPI_TX_TRIG_4W                  (0x1 << 16)
  91 #define SPI_DMA_BLK_COUNT(count)        (((count) - 1) & 0xFFFF)
  92
  93 #define SPI_TX_FIFO                     0x10
  94 #define SPI_RX_FIFO                     0x20
  95
  96 #define DATA_DIR_TX                     (1 << 0)
  97 #define DATA_DIR_RX                     (1 << 1)
  98
  99 #define MAX_CHIP_SELECT                 4
 100 #define SPI_FIFO_DEPTH                  4
 101 #define SPI_DMA_TIMEOUT               (msecs_to_jiffies(1000))
 102
 103 struct tegra_sflash_data {
 104         struct device                           *dev;
 105         struct spi_master                       *master;
 106         spinlock_t                              lock;
 107
 108         struct clk                              *clk;
 109         struct reset_control                    *rst;
 110         void __iomem                            *base;
 111         unsigned                                irq;
 112         u32                                     cur_speed;
 113
 114         struct spi_device                       *cur_spi;
 115         unsigned                                cur_pos;
 116         unsigned                                cur_len;
 117         unsigned                                bytes_per_word;
 118         unsigned                                cur_direction;
 119         unsigned                                curr_xfer_words;
 120
 121         unsigned                                cur_rx_pos;
 122         unsigned                                cur_tx_pos;
 123
 124         u32                                     tx_status;
 125         u32                                     rx_status;
 126         u32                                     status_reg;
 127
 128         u32                                     def_command_reg;
 129         u32                                     command_reg;
 130         u32                                     dma_control_reg;
 131
 132         struct completion                       xfer_completion;
 133         struct spi_transfer                     *curr_xfer;
 134 };
 135
 136 static int tegra_sflash_runtime_suspend(struct device *dev);
 137 static int tegra_sflash_runtime_resume(struct device *dev);
 138
 139 static inline u32 tegra_sflash_readl(struct tegra_sflash_data *tsd,
 140                 unsigned long reg)
 141 {
 142         return readl(tsd->base + reg);
 143 }
 144
 145 static inline void tegra_sflash_writel(struct tegra_sflash_data *tsd,
 146                 u32 val, unsigned long reg)
 147 {
 148         writel(val, tsd->base + reg);
 149 }
 150
 151 static void tegra_sflash_clear_status(struct tegra_sflash_data *tsd)
 152 {
 153         /* Write 1 to clear status register */
 154         tegra_sflash_writel(tsd, SPI_RDY | SPI_FIFO_ERROR, SPI_STATUS);
 155 }
 156
 157 static unsigned tegra_sflash_calculate_curr_xfer_param(
 158         struct spi_device *spi, struct tegra_sflash_data *tsd,
 159         struct spi_transfer *t)
 160 {
 161         unsigned remain_len = t->len - tsd->cur_pos;
 162         unsigned max_word;
 163
 164         tsd->bytes_per_word = DIV_ROUND_UP(t->bits_per_word, 8);
 165         max_word = remain_len / tsd->bytes_per_word;
 166         if (max_word > SPI_FIFO_DEPTH)
 167                 max_word = SPI_FIFO_DEPTH;
 168         tsd->curr_xfer_words = max_word;
 169         return max_word;
 170 }
 171
 172 static unsigned tegra_sflash_fill_tx_fifo_from_client_txbuf(
 173         struct tegra_sflash_data *tsd, struct spi_transfer *t)
 174 {
 175         unsigned nbytes;
 176         u32 status;
 177         unsigned max_n_32bit = tsd->curr_xfer_words;
 178         u8 *tx_buf = (u8 *)t->tx_buf + tsd->cur_tx_pos;
 179
 180         if (max_n_32bit > SPI_FIFO_DEPTH)
 181                 max_n_32bit = SPI_FIFO_DEPTH;
 182         nbytes = max_n_32bit * tsd->bytes_per_word;
 183
 184         status = tegra_sflash_readl(tsd, SPI_STATUS);
 185         while (!(status & SPI_TXF_FULL)) {
 186                 int i;
 187                 u32 x = 0;
 188
 189                 for (i = 0; nbytes && (i < tsd->bytes_per_word);
 190                                                         i++, nbytes--)
 191                         x |= (u32)(*tx_buf++) << (i * 8);
 192                 tegra_sflash_writel(tsd, x, SPI_TX_FIFO);
 193                 if (!nbytes)
 194                         break;
 195
 196                 status = tegra_sflash_readl(tsd, SPI_STATUS);
 197         }
 198         tsd->cur_tx_pos += max_n_32bit * tsd->bytes_per_word;
 199         return max_n_32bit;
 200 }
 201
 202 static int tegra_sflash_read_rx_fifo_to_client_rxbuf(
 203                 struct tegra_sflash_data *tsd, struct spi_transfer *t)
 204 {
 205         u32 status;
 206         unsigned int read_words = 0;
 207         u8 *rx_buf = (u8 *)t->rx_buf + tsd->cur_rx_pos;
 208
 209         status = tegra_sflash_readl(tsd, SPI_STATUS);
 210         while (!(status & SPI_RXF_EMPTY)) {
 211                 int i;
 212                 u32 x = tegra_sflash_readl(tsd, SPI_RX_FIFO);
 213
 214                 for (i = 0; (i < tsd->bytes_per_word); i++)
 215                         *rx_buf++ = (x >> (i*8)) & 0xFF;
 216                 read_words++;
 217                 status = tegra_sflash_readl(tsd, SPI_STATUS);
 218         }
 219         tsd->cur_rx_pos += read_words * tsd->bytes_per_word;
 220         return 0;
 221 }
 222
 223 static int tegra_sflash_start_cpu_based_transfer(
 224                 struct tegra_sflash_data *tsd, struct spi_transfer *t)
 225 {
 226         u32 val = 0;
 227         unsigned cur_words;
 228
 229         if (tsd->cur_direction & DATA_DIR_TX)
 230                 val |= SPI_IE_TXC;
 231
 232         if (tsd->cur_direction & DATA_DIR_RX)
 233                 val |= SPI_IE_RXC;
 234
 235         tegra_sflash_writel(tsd, val, SPI_DMA_CTL);
 236         tsd->dma_control_reg = val;
 237
 238         if (tsd->cur_direction & DATA_DIR_TX)
 239                 cur_words = tegra_sflash_fill_tx_fifo_from_client_txbuf(tsd, t);
 240         else
 241                 cur_words = tsd->curr_xfer_words;
 242         val |= SPI_DMA_BLK_COUNT(cur_words);
 243         tegra_sflash_writel(tsd, val, SPI_DMA_CTL);
 244         tsd->dma_control_reg = val;
 245         val |= SPI_DMA_EN;
 246         tegra_sflash_writel(tsd, val, SPI_DMA_CTL);
 247         return 0;
 248 }
 249
 250 static int tegra_sflash_start_transfer_one(struct spi_device *spi,
 251                 struct spi_transfer *t, bool is_first_of_msg,
 252                 bool is_single_xfer)
 253 {
 254         struct tegra_sflash_data *tsd = spi_master_get_devdata(spi->master);
 255         u32 speed;
 256         u32 command;
 257
 258         speed = t->speed_hz;
 259         if (speed != tsd->cur_speed) {
 260                 clk_set_rate(tsd->clk, speed);
 261                 tsd->cur_speed = speed;
 262         }
 263
 264         tsd->cur_spi = spi;
 265         tsd->cur_pos = 0;
 266         tsd->cur_rx_pos = 0;
 267         tsd->cur_tx_pos = 0;
 268         tsd->curr_xfer = t;
 269         tegra_sflash_calculate_curr_xfer_param(spi, tsd, t);
 270         if (is_first_of_msg) {
 271                 command = tsd->def_command_reg;
 272                 command |= SPI_BIT_LENGTH(t->bits_per_word - 1);
 273                 command |= SPI_CS_VAL_HIGH;
 274
 275                 command &= ~SPI_MODES;
 276                 if (spi->mode & SPI_CPHA)
 277                         command |= SPI_CK_SDA_FALLING;
 278
 279                 if (spi->mode & SPI_CPOL)
 280                         command |= SPI_ACTIVE_SCLK_DRIVE_HIGH;
 281                 else
 282                         command |= SPI_ACTIVE_SCLK_DRIVE_LOW;
 283                 command |= SPI_CS0_EN << spi->chip_select;
 284         } else {
 285                 command = tsd->command_reg;
 286                 command &= ~SPI_BIT_LENGTH(~0);
 287                 command |= SPI_BIT_LENGTH(t->bits_per_word - 1);
 288                 command &= ~(SPI_RX_EN | SPI_TX_EN);
 289         }
 290
 291         tsd->cur_direction = 0;
 292         if (t->rx_buf) {
 293                 command |= SPI_RX_EN;
 294                 tsd->cur_direction |= DATA_DIR_RX;
 295         }
 296         if (t->tx_buf) {
 297                 command |= SPI_TX_EN;
 298                 tsd->cur_direction |= DATA_DIR_TX;
 299         }
 300         tegra_sflash_writel(tsd, command, SPI_COMMAND);
 301         tsd->command_reg = command;
 302
 303         return tegra_sflash_start_cpu_based_transfer(tsd, t);
 304 }
 305
 306 static int tegra_sflash_transfer_one_message(struct spi_master *master,
 307                         struct spi_message *msg)
 308 {
 309         bool is_first_msg = true;
 310         int single_xfer;
 311         struct tegra_sflash_data *tsd = spi_master_get_devdata(master);
 312         struct spi_transfer *xfer;
 313         struct spi_device *spi = msg->spi;
 314         int ret;
 315
 316         msg->status = 0;
 317         msg->actual_length = 0;
 318         single_xfer = list_is_singular(&msg->transfers);
 319         list_for_each_entry(xfer, &msg->transfers, transfer_list) {
 320                 reinit_completion(&tsd->xfer_completion);
 321                 ret = tegra_sflash_start_transfer_one(spi, xfer,
 322                                         is_first_msg, single_xfer);
 323                 if (ret < 0) {
 324                         dev_err(tsd->dev,
 325                                 "spi can not start transfer, err %d\n", ret);
 326                         goto exit;
 327                 }
 328                 is_first_msg = false;
 329                 ret = wait_for_completion_timeout(&tsd->xfer_completion,
 330                                                 SPI_DMA_TIMEOUT);
 331                 if (WARN_ON(ret == 0)) {
 332                         dev_err(tsd->dev,
 333                                 "spi transfer timeout, err %d\n", ret);
 334                         ret = -EIO;
 335                         goto exit;
 336                 }
 337
 338                 if (tsd->tx_status ||  tsd->rx_status) {
 339                         dev_err(tsd->dev, "Error in Transfer\n");
 340                         ret = -EIO;
 341                         goto exit;
 342                 }
 343                 msg->actual_length += xfer->len;
 344                 if (xfer->cs_change && xfer->delay_usecs) {
 345                         tegra_sflash_writel(tsd, tsd->def_command_reg,
 346                                         SPI_COMMAND);
 347                         udelay(xfer->delay_usecs);
 348                 }
 349         }
 350         ret = 0;
 351 exit:
 352         tegra_sflash_writel(tsd, tsd->def_command_reg, SPI_COMMAND);
 353         msg->status = ret;
 354         spi_finalize_current_message(master);
 355         return ret;
 356 }
 357
 358 static irqreturn_t handle_cpu_based_xfer(struct tegra_sflash_data *tsd)
 359 {
 360         struct spi_transfer *t = tsd->curr_xfer;
 361         unsigned long flags;
 362
 363         spin_lock_irqsave(&tsd->lock, flags);
 364         if (tsd->tx_status || tsd->rx_status || (tsd->status_reg & SPI_BSY)) {
 365                 dev_err(tsd->dev,
 366                         "CpuXfer ERROR bit set 0x%x\n", tsd->status_reg);
 367                 dev_err(tsd->dev,
 368                         "CpuXfer 0x%08x:0x%08x\n", tsd->command_reg,
 369                                 tsd->dma_control_reg);
 370                 reset_control_assert(tsd->rst);
 371                 udelay(2);
 372                 reset_control_deassert(tsd->rst);
 373                 complete(&tsd->xfer_completion);
 374                 goto exit;
 375         }
 376
 377         if (tsd->cur_direction & DATA_DIR_RX)
 378                 tegra_sflash_read_rx_fifo_to_client_rxbuf(tsd, t);
 379
 380         if (tsd->cur_direction & DATA_DIR_TX)
 381                 tsd->cur_pos = tsd->cur_tx_pos;
 382         else
 383                 tsd->cur_pos = tsd->cur_rx_pos;
 384
 385         if (tsd->cur_pos == t->len) {
 386                 complete(&tsd->xfer_completion);
 387                 goto exit;
 388         }
 389
 390         tegra_sflash_calculate_curr_xfer_param(tsd->cur_spi, tsd, t);
 391         tegra_sflash_start_cpu_based_transfer(tsd, t);
 392 exit:
 393         spin_unlock_irqrestore(&tsd->lock, flags);
 394         return IRQ_HANDLED;
 395 }
 396
 397 static irqreturn_t tegra_sflash_isr(int irq, void *context_data)
 398 {
 399         struct tegra_sflash_data *tsd = context_data;
 400
 401         tsd->status_reg = tegra_sflash_readl(tsd, SPI_STATUS);
 402         if (tsd->cur_direction & DATA_DIR_TX)
 403                 tsd->tx_status = tsd->status_reg & SPI_TX_OVF;
 404
 405         if (tsd->cur_direction & DATA_DIR_RX)
 406                 tsd->rx_status = tsd->status_reg & SPI_RX_UNF;
 407         tegra_sflash_clear_status(tsd);
 408
 409         return handle_cpu_based_xfer(tsd);
 410 }
 411
 412 static const struct of_device_id tegra_sflash_of_match[] = {
 413         { .compatible = "nvidia,tegra20-sflash", },
 414         {}
 415 };
 416 MODULE_DEVICE_TABLE(of, tegra_sflash_of_match);
 417
 418 static int tegra_sflash_probe(struct platform_device *pdev)
 419 {
 420         struct spi_master       *master;
 421         struct tegra_sflash_data        *tsd;
 422         int ret;
 423         const struct of_device_id *match;
 424
 425         match = of_match_device(tegra_sflash_of_match, &pdev->dev);
 426         if (!match) {
 427                 dev_err(&pdev->dev, "Error: No device match found\n");
 428                 return -ENODEV;
 429         }
 430
 431         master = spi_alloc_master(&pdev->dev, sizeof(*tsd));
 432         if (!master) {
 433                 dev_err(&pdev->dev, "master allocation failed\n");
 434                 return -ENOMEM;
 435         }
 436
 437         /* the spi->mode bits understood by this driver: */
 438         master->mode_bits = SPI_CPOL | SPI_CPHA;
 439         master->transfer_one_message = tegra_sflash_transfer_one_message;
 440         master->auto_runtime_pm = true;
 441         master->num_chipselect = MAX_CHIP_SELECT;
 442
 443         platform_set_drvdata(pdev, master);
 444         tsd = spi_master_get_devdata(master);
 445         tsd->master = master;
 446         tsd->dev = &pdev->dev;
 447         spin_lock_init(&tsd->lock);
 448
 449         if (of_property_read_u32(tsd->dev->of_node, "spi-max-frequency",
 450                                  &master->max_speed_hz))
 451                 master->max_speed_hz = 25000000; /* 25MHz */
 452
 453         tsd->base = devm_platform_ioremap_resource(pdev, 0);
 454         if (IS_ERR(tsd->base)) {
 455                 ret = PTR_ERR(tsd->base);
 456                 goto exit_free_master;
 457         }
 458
 459         tsd->irq = platform_get_irq(pdev, 0);
 460         ret = request_irq(tsd->irq, tegra_sflash_isr, 0,
 461                         dev_name(&pdev->dev), tsd);
 462         if (ret < 0) {
 463                 dev_err(&pdev->dev, "Failed to register ISR for IRQ %d\n",
 464                                         tsd->irq);
 465                 goto exit_free_master;
 466         }
 467
 468         tsd->clk = devm_clk_get(&pdev->dev, NULL);
 469         if (IS_ERR(tsd->clk)) {
 470                 dev_err(&pdev->dev, "can not get clock\n");
 471                 ret = PTR_ERR(tsd->clk);
 472                 goto exit_free_irq;
 473         }
 474
 475         tsd->rst = devm_reset_control_get_exclusive(&pdev->dev, "spi");
 476         if (IS_ERR(tsd->rst)) {
 477                 dev_err(&pdev->dev, "can not get reset\n");
 478                 ret = PTR_ERR(tsd->rst);
 479                 goto exit_free_irq;
 480         }
 481
 482         init_completion(&tsd->xfer_completion);
 483         pm_runtime_enable(&pdev->dev);
 484         if (!pm_runtime_enabled(&pdev->dev)) {
 485                 ret = tegra_sflash_runtime_resume(&pdev->dev);
 486                 if (ret)
 487                         goto exit_pm_disable;
 488         }
 489
 490         ret = pm_runtime_get_sync(&pdev->dev);
 491         if (ret < 0) {
 492                 dev_err(&pdev->dev, "pm runtime get failed, e = %d\n", ret);
 493                 goto exit_pm_disable;
 494         }
 495
 496         /* Reset controller */
 497         reset_control_assert(tsd->rst);
 498         udelay(2);
 499         reset_control_deassert(tsd->rst);
 500
 501         tsd->def_command_reg  = SPI_M_S | SPI_CS_SW;
 502         tegra_sflash_writel(tsd, tsd->def_command_reg, SPI_COMMAND);
 503         pm_runtime_put(&pdev->dev);
 504
 505         master->dev.of_node = pdev->dev.of_node;
 506         ret = devm_spi_register_master(&pdev->dev, master);
 507         if (ret < 0) {
 508                 dev_err(&pdev->dev, "can not register to master err %d\n", ret);
 509                 goto exit_pm_disable;
 510         }
 511         return ret;
 512
 513 exit_pm_disable:
 514         pm_runtime_disable(&pdev->dev);
 515         if (!pm_runtime_status_suspended(&pdev->dev))
 516                 tegra_sflash_runtime_suspend(&pdev->dev);
 517 exit_free_irq:
 518         free_irq(tsd->irq, tsd);
 519 exit_free_master:
 520         spi_master_put(master);
 521         return ret;
 522 }
 523
 524 static int tegra_sflash_remove(struct platform_device *pdev)
 525 {
 526         struct spi_master *master = platform_get_drvdata(pdev);
 527         struct tegra_sflash_data        *tsd = spi_master_get_devdata(master);
 528
 529         free_irq(tsd->irq, tsd);
 530
 531         pm_runtime_disable(&pdev->dev);
 532         if (!pm_runtime_status_suspended(&pdev->dev))
 533                 tegra_sflash_runtime_suspend(&pdev->dev);
 534
 535         return 0;
 536 }
 537
 538 #ifdef CONFIG_PM_SLEEP
 539 static int tegra_sflash_suspend(struct device *dev)
 540 {
 541         struct spi_master *master = dev_get_drvdata(dev);
 542
 543         return spi_master_suspend(master);
 544 }
 545
 546 static int tegra_sflash_resume(struct device *dev)
 547 {
 548         struct spi_master *master = dev_get_drvdata(dev);
 549         struct tegra_sflash_data *tsd = spi_master_get_devdata(master);
 550         int ret;
 551
 552         ret = pm_runtime_get_sync(dev);
 553         if (ret < 0) {
 554                 dev_err(dev, "pm runtime failed, e = %d\n", ret);
 555                 return ret;
 556         }
 557         tegra_sflash_writel(tsd, tsd->command_reg, SPI_COMMAND);
 558         pm_runtime_put(dev);
 559
 560         return spi_master_resume(master);
 561 }
 562 #endif
 563
 564 static int tegra_sflash_runtime_suspend(struct device *dev)
 565 {
 566         struct spi_master *master = dev_get_drvdata(dev);
 567         struct tegra_sflash_data *tsd = spi_master_get_devdata(master);
 568
 569         /* Flush all write which are in PPSB queue by reading back */
 570         tegra_sflash_readl(tsd, SPI_COMMAND);
 571
 572         clk_disable_unprepare(tsd->clk);
 573         return 0;
 574 }
 575
 576 static int tegra_sflash_runtime_resume(struct device *dev)
 577 {
 578         struct spi_master *master = dev_get_drvdata(dev);
 579         struct tegra_sflash_data *tsd = spi_master_get_devdata(master);
 580         int ret;
 581
 582         ret = clk_prepare_enable(tsd->clk);
 583         if (ret < 0) {
 584                 dev_err(tsd->dev, "clk_prepare failed: %d\n", ret);
 585                 return ret;
 586         }
 587         return 0;
 588 }
 589
 590 static const struct dev_pm_ops slink_pm_ops = {
 591         SET_RUNTIME_PM_OPS(tegra_sflash_runtime_suspend,
 592                 tegra_sflash_runtime_resume, NULL)
 593         SET_SYSTEM_SLEEP_PM_OPS(tegra_sflash_suspend, tegra_sflash_resume)
 594 };
 595 static struct platform_driver tegra_sflash_driver = {
 596         .driver = {
 597                 .name           = "spi-tegra-sflash",
 598                 .pm             = &slink_pm_ops,
 599                 .of_match_table = tegra_sflash_of_match,
 600         },
 601         .probe =        tegra_sflash_probe,
 602         .remove =       tegra_sflash_remove,
 603 };
 604 module_platform_driver(tegra_sflash_driver);
 605
 606 MODULE_ALIAS("platform:spi-tegra-sflash");
 607 MODULE_DESCRIPTION("NVIDIA Tegra20 Serial Flash Controller Driver");
 608 MODULE_AUTHOR("Laxman Dewangan <ldewangan@nvidia.com>");
 609 MODULE_LICENSE("GPL v2");