drivers/spi/spi-st-ssc4.c

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