drivers/spi/spi-st-ssc4.c

   1 /*
   2  *  Copyright (c) 2008-2014 STMicroelectronics Limited
   3  *
   4  *  Author: Angus Clark <Angus.Clark@st.com>
   5  *          Patrice Chotard <patrice.chotard@st.com>
   6  *          Lee Jones <lee.jones@linaro.org>
   7  *
   8  *  SPI master mode controller driver, used in STMicroelectronics devices.
   9  *
  10  *  May be copied or modified under the terms of the GNU General Public
  11  *  License Version 2.0 only.  See linux/COPYING for more information.
  12  */
  13
  14 #include <linux/clk.h>
  15 #include <linux/delay.h>
  16 #include <linux/interrupt.h>
  17 #include <linux/io.h>
  18 #include <linux/module.h>
  19 #include <linux/pinctrl/consumer.h>
  20 #include <linux/platform_device.h>
  21 #include <linux/of.h>
  22 #include <linux/of_gpio.h>
  23 #include <linux/of_irq.h>
  24 #include <linux/pm_runtime.h>
  25 #include <linux/spi/spi.h>
  26 #include <linux/spi/spi_bitbang.h>
  27
  28 /* SSC registers */
  29 #define SSC_BRG                         0x000
  30 #define SSC_TBUF                        0x004
  31 #define SSC_RBUF                        0x008
  32 #define SSC_CTL                         0x00C
  33 #define SSC_IEN                         0x010
  34 #define SSC_I2C                         0x018
  35
  36 /* SSC Control */
  37 #define SSC_CTL_DATA_WIDTH_9            0x8
  38 #define SSC_CTL_DATA_WIDTH_MSK          0xf
  39 #define SSC_CTL_BM                      0xf
  40 #define SSC_CTL_HB                      BIT(4)
  41 #define SSC_CTL_PH                      BIT(5)
  42 #define SSC_CTL_PO                      BIT(6)
  43 #define SSC_CTL_SR                      BIT(7)
  44 #define SSC_CTL_MS                      BIT(8)
  45 #define SSC_CTL_EN                      BIT(9)
  46 #define SSC_CTL_LPB                     BIT(10)
  47 #define SSC_CTL_EN_TX_FIFO              BIT(11)
  48 #define SSC_CTL_EN_RX_FIFO              BIT(12)
  49 #define SSC_CTL_EN_CLST_RX              BIT(13)
  50
  51 /* SSC Interrupt Enable */
  52 #define SSC_IEN_TEEN                    BIT(2)
  53
  54 #define FIFO_SIZE                       8
  55
  56 struct spi_st {
  57         /* SSC SPI Controller */
  58         void __iomem            *base;
  59         struct clk              *clk;
  60         struct device           *dev;
  61
  62         /* SSC SPI current transaction */
  63         const u8                *tx_ptr;
  64         u8                      *rx_ptr;
  65         u16                     bytes_per_word;
  66         unsigned int            words_remaining;
  67         unsigned int            baud;
  68         struct completion       done;
  69 };
  70
  71 /* Load the TX FIFO */
  72 static void ssc_write_tx_fifo(struct spi_st *spi_st)
  73 {
  74         unsigned int count, i;
  75         uint32_t word = 0;
  76
  77         if (spi_st->words_remaining > FIFO_SIZE)
  78                 count = FIFO_SIZE;
  79         else
  80                 count = spi_st->words_remaining;
  81
  82         for (i = 0; i < count; i++) {
  83                 if (spi_st->tx_ptr) {
  84                         if (spi_st->bytes_per_word == 1) {
  85                                 word = *spi_st->tx_ptr++;
  86                         } else {
  87                                 word = *spi_st->tx_ptr++;
  88                                 word = *spi_st->tx_ptr++ | (word << 8);
  89                         }
  90                 }
  91                 writel_relaxed(word, spi_st->base + SSC_TBUF);
  92         }
  93 }
  94
  95 /* Read the RX FIFO */
  96 static void ssc_read_rx_fifo(struct spi_st *spi_st)
  97 {
  98         unsigned int count, i;
  99         uint32_t word = 0;
 100
 101         if (spi_st->words_remaining > FIFO_SIZE)
 102                 count = FIFO_SIZE;
 103         else
 104                 count = spi_st->words_remaining;
 105
 106         for (i = 0; i < count; i++) {
 107                 word = readl_relaxed(spi_st->base + SSC_RBUF);
 108
 109                 if (spi_st->rx_ptr) {
 110                         if (spi_st->bytes_per_word == 1) {
 111                                 *spi_st->rx_ptr++ = (uint8_t)word;
 112                         } else {
 113                                 *spi_st->rx_ptr++ = (word >> 8);
 114                                 *spi_st->rx_ptr++ = word & 0xff;
 115                         }
 116                 }
 117         }
 118         spi_st->words_remaining -= count;
 119 }
 120
 121 static int spi_st_transfer_one(struct spi_master *master,
 122                                struct spi_device *spi, struct spi_transfer *t)
 123 {
 124         struct spi_st *spi_st = spi_master_get_devdata(master);
 125         uint32_t ctl = 0;
 126
 127         /* Setup transfer */
 128         spi_st->tx_ptr = t->tx_buf;
 129         spi_st->rx_ptr = t->rx_buf;
 130
 131         if (spi->bits_per_word > 8) {
 132                 /*
 133                  * Anything greater than 8 bits-per-word requires 2
 134                  * bytes-per-word in the RX/TX buffers
 135                  */
 136                 spi_st->bytes_per_word = 2;
 137                 spi_st->words_remaining = t->len / 2;
 138
 139         } else if (spi->bits_per_word == 8 && !(t->len & 0x1)) {
 140                 /*
 141                  * If transfer is even-length, and 8 bits-per-word, then
 142                  * implement as half-length 16 bits-per-word transfer
 143                  */
 144                 spi_st->bytes_per_word = 2;
 145                 spi_st->words_remaining = t->len / 2;
 146
 147                 /* Set SSC_CTL to 16 bits-per-word */
 148                 ctl = readl_relaxed(spi_st->base + SSC_CTL);
 149                 writel_relaxed((ctl | 0xf), spi_st->base + SSC_CTL);
 150
 151                 readl_relaxed(spi_st->base + SSC_RBUF);
 152
 153         } else {
 154                 spi_st->bytes_per_word = 1;
 155                 spi_st->words_remaining = t->len;
 156         }
 157
 158         reinit_completion(&spi_st->done);
 159
 160         /* Start transfer by writing to the TX FIFO */
 161         ssc_write_tx_fifo(spi_st);
 162         writel_relaxed(SSC_IEN_TEEN, spi_st->base + SSC_IEN);
 163
 164         /* Wait for transfer to complete */
 165         wait_for_completion(&spi_st->done);
 166
 167         /* Restore SSC_CTL if necessary */
 168         if (ctl)
 169                 writel_relaxed(ctl, spi_st->base + SSC_CTL);
 170
 171         spi_finalize_current_transfer(spi->master);
 172
 173         return t->len;
 174 }
 175
 176 static void spi_st_cleanup(struct spi_device *spi)
 177 {
 178         gpio_free(spi->cs_gpio);
 179 }
 180
 181 /* the spi->mode bits understood by this driver: */
 182 #define MODEBITS  (SPI_CPOL | SPI_CPHA | SPI_LSB_FIRST | SPI_LOOP | SPI_CS_HIGH)
 183 static int spi_st_setup(struct spi_device *spi)
 184 {
 185         struct spi_st *spi_st = spi_master_get_devdata(spi->master);
 186         u32 spi_st_clk, sscbrg, var;
 187         u32 hz = spi->max_speed_hz;
 188         int cs = spi->cs_gpio;
 189         int ret;
 190
 191         if (!hz)  {
 192                 dev_err(&spi->dev, "max_speed_hz unspecified\n");
 193                 return -EINVAL;
 194         }
 195
 196         if (!gpio_is_valid(cs)) {
 197                 dev_err(&spi->dev, "%d is not a valid gpio\n", cs);
 198                 return -EINVAL;
 199         }
 200
 201         ret = gpio_request(cs, dev_name(&spi->dev));
 202         if (ret) {
 203                 dev_err(&spi->dev, "could not request gpio:%d\n", cs);
 204                 return ret;
 205         }
 206
 207         ret = gpio_direction_output(cs, spi->mode & SPI_CS_HIGH);
 208         if (ret)
 209                 goto out_free_gpio;
 210
 211         spi_st_clk = clk_get_rate(spi_st->clk);
 212
 213         /* Set SSC_BRF */
 214         sscbrg = spi_st_clk / (2 * hz);
 215         if (sscbrg < 0x07 || sscbrg > BIT(16)) {
 216                 dev_err(&spi->dev,
 217                         "baudrate %d outside valid range %d\n", sscbrg, hz);
 218                 ret = -EINVAL;
 219                 goto out_free_gpio;
 220         }
 221
 222         spi_st->baud = spi_st_clk / (2 * sscbrg);
 223         if (sscbrg == BIT(16)) /* 16-bit counter wraps */
 224                 sscbrg = 0x0;
 225
 226         writel_relaxed(sscbrg, spi_st->base + SSC_BRG);
 227
 228         dev_dbg(&spi->dev,
 229                 "setting baudrate:target= %u hz, actual= %u hz, sscbrg= %u\n",
 230                 hz, spi_st->baud, sscbrg);
 231
 232          /* Set SSC_CTL and enable SSC */
 233          var = readl_relaxed(spi_st->base + SSC_CTL);
 234          var |= SSC_CTL_MS;
 235
 236          if (spi->mode & SPI_CPOL)
 237                 var |= SSC_CTL_PO;
 238          else
 239                 var &= ~SSC_CTL_PO;
 240
 241          if (spi->mode & SPI_CPHA)
 242                 var |= SSC_CTL_PH;
 243          else
 244                 var &= ~SSC_CTL_PH;
 245
 246          if ((spi->mode & SPI_LSB_FIRST) == 0)
 247                 var |= SSC_CTL_HB;
 248          else
 249                 var &= ~SSC_CTL_HB;
 250
 251          if (spi->mode & SPI_LOOP)
 252                 var |= SSC_CTL_LPB;
 253          else
 254                 var &= ~SSC_CTL_LPB;
 255
 256          var &= ~SSC_CTL_DATA_WIDTH_MSK;
 257          var |= (spi->bits_per_word - 1);
 258
 259          var |= SSC_CTL_EN_TX_FIFO | SSC_CTL_EN_RX_FIFO;
 260          var |= SSC_CTL_EN;
 261
 262          writel_relaxed(var, spi_st->base + SSC_CTL);
 263
 264          /* Clear the status register */
 265          readl_relaxed(spi_st->base + SSC_RBUF);
 266
 267          return 0;
 268
 269 out_free_gpio:
 270         gpio_free(cs);
 271         return ret;
 272 }
 273
 274 /* Interrupt fired when TX shift register becomes empty */
 275 static irqreturn_t spi_st_irq(int irq, void *dev_id)
 276 {
 277         struct spi_st *spi_st = (struct spi_st *)dev_id;
 278
 279         /* Read RX FIFO */
 280         ssc_read_rx_fifo(spi_st);
 281
 282         /* Fill TX FIFO */
 283         if (spi_st->words_remaining) {
 284                 ssc_write_tx_fifo(spi_st);
 285         } else {
 286                 /* TX/RX complete */
 287                 writel_relaxed(0x0, spi_st->base + SSC_IEN);
 288                 /*
 289                  * read SSC_IEN to ensure that this bit is set
 290                  * before re-enabling interrupt
 291                  */
 292                 readl(spi_st->base + SSC_IEN);
 293                 complete(&spi_st->done);
 294         }
 295
 296         return IRQ_HANDLED;
 297 }
 298
 299 static int spi_st_probe(struct platform_device *pdev)
 300 {
 301         struct device_node *np = pdev->dev.of_node;
 302         struct spi_master *master;
 303         struct resource *res;
 304         struct spi_st *spi_st;
 305         int irq, ret = 0;
 306         u32 var;
 307
 308         master = spi_alloc_master(&pdev->dev, sizeof(*spi_st));
 309         if (!master)
 310                 return -ENOMEM;
 311
 312         master->dev.of_node             = np;
 313         master->mode_bits               = MODEBITS;
 314         master->setup                   = spi_st_setup;
 315         master->cleanup                 = spi_st_cleanup;
 316         master->transfer_one            = spi_st_transfer_one;
 317         master->bits_per_word_mask      = SPI_BPW_MASK(8) | SPI_BPW_MASK(16);
 318         master->auto_runtime_pm         = true;
 319         master->bus_num                 = pdev->id;
 320         spi_st                          = spi_master_get_devdata(master);
 321
 322         spi_st->clk = devm_clk_get(&pdev->dev, "ssc");
 323         if (IS_ERR(spi_st->clk)) {
 324                 dev_err(&pdev->dev, "Unable to request clock\n");
 325                 ret = PTR_ERR(spi_st->clk);
 326                 goto put_master;
 327         }
 328
 329         ret = clk_prepare_enable(spi_st->clk);
 330         if (ret)
 331                 goto put_master;
 332
 333         init_completion(&spi_st->done);
 334
 335         /* Get resources */
 336         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 337         spi_st->base = devm_ioremap_resource(&pdev->dev, res);
 338         if (IS_ERR(spi_st->base)) {
 339                 ret = PTR_ERR(spi_st->base);
 340                 goto clk_disable;
 341         }
 342
 343         /* Disable I2C and Reset SSC */
 344         writel_relaxed(0x0, spi_st->base + SSC_I2C);
 345         var = readw_relaxed(spi_st->base + SSC_CTL);
 346         var |= SSC_CTL_SR;
 347         writel_relaxed(var, spi_st->base + SSC_CTL);
 348
 349         udelay(1);
 350         var = readl_relaxed(spi_st->base + SSC_CTL);
 351         var &= ~SSC_CTL_SR;
 352         writel_relaxed(var, spi_st->base + SSC_CTL);
 353
 354         /* Set SSC into slave mode before reconfiguring PIO pins */
 355         var = readl_relaxed(spi_st->base + SSC_CTL);
 356         var &= ~SSC_CTL_MS;
 357         writel_relaxed(var, spi_st->base + SSC_CTL);
 358
 359         irq = irq_of_parse_and_map(np, 0);
 360         if (!irq) {
 361                 dev_err(&pdev->dev, "IRQ missing or invalid\n");
 362                 ret = -EINVAL;
 363                 goto clk_disable;
 364         }
 365
 366         ret = devm_request_irq(&pdev->dev, irq, spi_st_irq, 0,
 367                                pdev->name, spi_st);
 368         if (ret) {
 369                 dev_err(&pdev->dev, "Failed to request irq %d\n", irq);
 370                 goto clk_disable;
 371         }
 372
 373         /* by default the device is on */
 374         pm_runtime_set_active(&pdev->dev);
 375         pm_runtime_enable(&pdev->dev);
 376
 377         platform_set_drvdata(pdev, master);
 378
 379         ret = devm_spi_register_master(&pdev->dev, master);
 380         if (ret) {
 381                 dev_err(&pdev->dev, "Failed to register master\n");
 382                 goto clk_disable;
 383         }
 384
 385         return 0;
 386
 387 clk_disable:
 388         clk_disable_unprepare(spi_st->clk);
 389 put_master:
 390         spi_master_put(master);
 391         return ret;
 392 }
 393
 394 static int spi_st_remove(struct platform_device *pdev)
 395 {
 396         struct spi_master *master = platform_get_drvdata(pdev);
 397         struct spi_st *spi_st = spi_master_get_devdata(master);
 398
 399         clk_disable_unprepare(spi_st->clk);
 400
 401         pinctrl_pm_select_sleep_state(&pdev->dev);
 402
 403         return 0;
 404 }
 405
 406 #ifdef CONFIG_PM
 407 static int spi_st_runtime_suspend(struct device *dev)
 408 {
 409         struct spi_master *master = dev_get_drvdata(dev);
 410         struct spi_st *spi_st = spi_master_get_devdata(master);
 411
 412         writel_relaxed(0, spi_st->base + SSC_IEN);
 413         pinctrl_pm_select_sleep_state(dev);
 414
 415         clk_disable_unprepare(spi_st->clk);
 416
 417         return 0;
 418 }
 419
 420 static int spi_st_runtime_resume(struct device *dev)
 421 {
 422         struct spi_master *master = dev_get_drvdata(dev);
 423         struct spi_st *spi_st = spi_master_get_devdata(master);
 424         int ret;
 425
 426         ret = clk_prepare_enable(spi_st->clk);
 427         pinctrl_pm_select_default_state(dev);
 428
 429         return ret;
 430 }
 431 #endif
 432
 433 #ifdef CONFIG_PM_SLEEP
 434 static int spi_st_suspend(struct device *dev)
 435 {
 436         struct spi_master *master = dev_get_drvdata(dev);
 437         int ret;
 438
 439         ret = spi_master_suspend(master);
 440         if (ret)
 441                 return ret;
 442
 443         return pm_runtime_force_suspend(dev);
 444 }
 445
 446 static int spi_st_resume(struct device *dev)
 447 {
 448         struct spi_master *master = dev_get_drvdata(dev);
 449         int ret;
 450
 451         ret = spi_master_resume(master);
 452         if (ret)
 453                 return ret;
 454
 455         return pm_runtime_force_resume(dev);
 456 }
 457 #endif
 458
 459 static const struct dev_pm_ops spi_st_pm = {
 460         SET_SYSTEM_SLEEP_PM_OPS(spi_st_suspend, spi_st_resume)
 461         SET_RUNTIME_PM_OPS(spi_st_runtime_suspend, spi_st_runtime_resume, NULL)
 462 };
 463
 464 static const struct of_device_id stm_spi_match[] = {
 465         { .compatible = "st,comms-ssc4-spi", },
 466         {},
 467 };
 468 MODULE_DEVICE_TABLE(of, stm_spi_match);
 469
 470 static struct platform_driver spi_st_driver = {
 471         .driver = {
 472                 .name = "spi-st",
 473                 .pm = &spi_st_pm,
 474                 .of_match_table = of_match_ptr(stm_spi_match),
 475         },
 476         .probe = spi_st_probe,
 477         .remove = spi_st_remove,
 478 };
 479 module_platform_driver(spi_st_driver);
 480
 481 MODULE_AUTHOR("Patrice Chotard <patrice.chotard@st.com>");
 482 MODULE_DESCRIPTION("STM SSC SPI driver");
 483 MODULE_LICENSE("GPL v2");