drivers/spi/spi-npcm-pspi.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 // Copyright (c) 2018 Nuvoton Technology corporation.
   3
   4 #include <linux/kernel.h>
   5 #include <linux/bitfield.h>
   6 #include <linux/bitops.h>
   7 #include <linux/clk.h>
   8 #include <linux/interrupt.h>
   9 #include <linux/io.h>
  10 #include <linux/module.h>
  11 #include <linux/platform_device.h>
  12 #include <linux/spi/spi.h>
  13 #include <linux/gpio.h>
  14 #include <linux/of_gpio.h>
  15
  16 #include <asm/unaligned.h>
  17
  18 #include <linux/regmap.h>
  19 #include <linux/mfd/syscon.h>
  20
  21 struct npcm_pspi {
  22         struct completion xfer_done;
  23         struct regmap *rst_regmap;
  24         struct spi_master *master;
  25         unsigned int tx_bytes;
  26         unsigned int rx_bytes;
  27         void __iomem *base;
  28         bool is_save_param;
  29         u8 bits_per_word;
  30         const u8 *tx_buf;
  31         struct clk *clk;
  32         u32 speed_hz;
  33         u8 *rx_buf;
  34         u16 mode;
  35         u32 id;
  36 };
  37
  38 #define DRIVER_NAME "npcm-pspi"
  39
  40 #define NPCM_PSPI_DATA          0x00
  41 #define NPCM_PSPI_CTL1          0x02
  42 #define NPCM_PSPI_STAT          0x04
  43
  44 /* definitions for control and status register */
  45 #define NPCM_PSPI_CTL1_SPIEN    BIT(0)
  46 #define NPCM_PSPI_CTL1_MOD      BIT(2)
  47 #define NPCM_PSPI_CTL1_EIR      BIT(5)
  48 #define NPCM_PSPI_CTL1_EIW      BIT(6)
  49 #define NPCM_PSPI_CTL1_SCM      BIT(7)
  50 #define NPCM_PSPI_CTL1_SCIDL    BIT(8)
  51 #define NPCM_PSPI_CTL1_SCDV6_0  GENMASK(15, 9)
  52
  53 #define NPCM_PSPI_STAT_BSY      BIT(0)
  54 #define NPCM_PSPI_STAT_RBF      BIT(1)
  55
  56 /* general definitions */
  57 #define NPCM_PSPI_TIMEOUT_MS            2000
  58 #define NPCM_PSPI_MAX_CLK_DIVIDER       256
  59 #define NPCM_PSPI_MIN_CLK_DIVIDER       4
  60 #define NPCM_PSPI_DEFAULT_CLK           25000000
  61
  62 /* reset register */
  63 #define NPCM7XX_IPSRST2_OFFSET  0x24
  64
  65 #define NPCM7XX_PSPI1_RESET     BIT(22)
  66 #define NPCM7XX_PSPI2_RESET     BIT(23)
  67
  68 static inline unsigned int bytes_per_word(unsigned int bits)
  69 {
  70         return bits <= 8 ? 1 : 2;
  71 }
  72
  73 static inline void npcm_pspi_irq_enable(struct npcm_pspi *priv, u16 mask)
  74 {
  75         u16 val;
  76
  77         val = ioread16(priv->base + NPCM_PSPI_CTL1);
  78         val |= mask;
  79         iowrite16(val, priv->base + NPCM_PSPI_CTL1);
  80 }
  81
  82 static inline void npcm_pspi_irq_disable(struct npcm_pspi *priv, u16 mask)
  83 {
  84         u16 val;
  85
  86         val = ioread16(priv->base + NPCM_PSPI_CTL1);
  87         val &= ~mask;
  88         iowrite16(val, priv->base + NPCM_PSPI_CTL1);
  89 }
  90
  91 static inline void npcm_pspi_enable(struct npcm_pspi *priv)
  92 {
  93         u16 val;
  94
  95         val = ioread16(priv->base + NPCM_PSPI_CTL1);
  96         val |= NPCM_PSPI_CTL1_SPIEN;
  97         iowrite16(val, priv->base + NPCM_PSPI_CTL1);
  98 }
  99
 100 static inline void npcm_pspi_disable(struct npcm_pspi *priv)
 101 {
 102         u16 val;
 103
 104         val = ioread16(priv->base + NPCM_PSPI_CTL1);
 105         val &= ~NPCM_PSPI_CTL1_SPIEN;
 106         iowrite16(val, priv->base + NPCM_PSPI_CTL1);
 107 }
 108
 109 static void npcm_pspi_set_mode(struct spi_device *spi)
 110 {
 111         struct npcm_pspi *priv = spi_master_get_devdata(spi->master);
 112         u16 regtemp;
 113         u16 mode_val;
 114
 115         switch (spi->mode & (SPI_CPOL | SPI_CPHA)) {
 116         case SPI_MODE_0:
 117                 mode_val = 0;
 118                 break;
 119         case SPI_MODE_1:
 120                 mode_val = NPCM_PSPI_CTL1_SCIDL;
 121                 break;
 122         case SPI_MODE_2:
 123                 mode_val = NPCM_PSPI_CTL1_SCM;
 124                 break;
 125         case SPI_MODE_3:
 126                 mode_val = NPCM_PSPI_CTL1_SCIDL | NPCM_PSPI_CTL1_SCM;
 127                 break;
 128         }
 129
 130         regtemp = ioread16(priv->base + NPCM_PSPI_CTL1);
 131         regtemp &= ~(NPCM_PSPI_CTL1_SCM | NPCM_PSPI_CTL1_SCIDL);
 132         iowrite16(regtemp | mode_val, priv->base + NPCM_PSPI_CTL1);
 133 }
 134
 135 static void npcm_pspi_set_transfer_size(struct npcm_pspi *priv, int size)
 136 {
 137         u16 regtemp;
 138
 139         regtemp = ioread16(NPCM_PSPI_CTL1 + priv->base);
 140
 141         switch (size) {
 142         case 8:
 143                 regtemp &= ~NPCM_PSPI_CTL1_MOD;
 144                 break;
 145         case 16:
 146                 regtemp |= NPCM_PSPI_CTL1_MOD;
 147                 break;
 148         }
 149
 150         iowrite16(regtemp, NPCM_PSPI_CTL1 + priv->base);
 151 }
 152
 153 static void npcm_pspi_set_baudrate(struct npcm_pspi *priv, unsigned int speed)
 154 {
 155         u32 ckdiv;
 156         u16 regtemp;
 157
 158         /* the supported rates are numbers from 4 to 256. */
 159         ckdiv = DIV_ROUND_CLOSEST(clk_get_rate(priv->clk), (2 * speed)) - 1;
 160
 161         regtemp = ioread16(NPCM_PSPI_CTL1 + priv->base);
 162         regtemp &= ~NPCM_PSPI_CTL1_SCDV6_0;
 163         iowrite16(regtemp | (ckdiv << 9), NPCM_PSPI_CTL1 + priv->base);
 164 }
 165
 166 static void npcm_pspi_setup_transfer(struct spi_device *spi,
 167                                      struct spi_transfer *t)
 168 {
 169         struct npcm_pspi *priv = spi_master_get_devdata(spi->master);
 170
 171         priv->tx_buf = t->tx_buf;
 172         priv->rx_buf = t->rx_buf;
 173         priv->tx_bytes = t->len;
 174         priv->rx_bytes = t->len;
 175
 176         if (!priv->is_save_param || priv->mode != spi->mode) {
 177                 npcm_pspi_set_mode(spi);
 178                 priv->mode = spi->mode;
 179         }
 180
 181         if (!priv->is_save_param || priv->bits_per_word != t->bits_per_word) {
 182                 npcm_pspi_set_transfer_size(priv, t->bits_per_word);
 183                 priv->bits_per_word = t->bits_per_word;
 184         }
 185
 186         if (!priv->is_save_param || priv->speed_hz != t->speed_hz) {
 187                 npcm_pspi_set_baudrate(priv, t->speed_hz);
 188                 priv->speed_hz = t->speed_hz;
 189         }
 190
 191         if (!priv->is_save_param)
 192                 priv->is_save_param = true;
 193 }
 194
 195 static void npcm_pspi_send(struct npcm_pspi *priv)
 196 {
 197         int wsize;
 198
 199         wsize = min(bytes_per_word(priv->bits_per_word), priv->tx_bytes);
 200         priv->tx_bytes -= wsize;
 201
 202         if (!priv->tx_buf)
 203                 return;
 204
 205         switch (wsize) {
 206         case 1:
 207                 iowrite8(*priv->tx_buf, NPCM_PSPI_DATA + priv->base);
 208                 break;
 209         case 2:
 210                 iowrite16(*priv->tx_buf, NPCM_PSPI_DATA + priv->base);
 211                 break;
 212         default:
 213                 WARN_ON_ONCE(1);
 214                 return;
 215         }
 216
 217         priv->tx_buf += wsize;
 218 }
 219
 220 static void npcm_pspi_recv(struct npcm_pspi *priv)
 221 {
 222         int rsize;
 223         u16 val;
 224
 225         rsize = min(bytes_per_word(priv->bits_per_word), priv->rx_bytes);
 226         priv->rx_bytes -= rsize;
 227
 228         if (!priv->rx_buf)
 229                 return;
 230
 231         switch (rsize) {
 232         case 1:
 233                 val = ioread8(priv->base + NPCM_PSPI_DATA);
 234                 break;
 235         case 2:
 236                 val = ioread16(priv->base + NPCM_PSPI_DATA);
 237                 break;
 238         default:
 239                 WARN_ON_ONCE(1);
 240                 return;
 241         }
 242
 243         *priv->rx_buf = val;
 244         priv->rx_buf += rsize;
 245 }
 246
 247 static int npcm_pspi_transfer_one(struct spi_master *master,
 248                                   struct spi_device *spi,
 249                                   struct spi_transfer *t)
 250 {
 251         struct npcm_pspi *priv = spi_master_get_devdata(master);
 252         int status;
 253
 254         npcm_pspi_setup_transfer(spi, t);
 255         reinit_completion(&priv->xfer_done);
 256         npcm_pspi_enable(priv);
 257         status = wait_for_completion_timeout(&priv->xfer_done,
 258                                              msecs_to_jiffies
 259                                              (NPCM_PSPI_TIMEOUT_MS));
 260         if (status == 0) {
 261                 npcm_pspi_disable(priv);
 262                 return -ETIMEDOUT;
 263         }
 264
 265         return 0;
 266 }
 267
 268 static int npcm_pspi_prepare_transfer_hardware(struct spi_master *master)
 269 {
 270         struct npcm_pspi *priv = spi_master_get_devdata(master);
 271
 272         npcm_pspi_irq_enable(priv, NPCM_PSPI_CTL1_EIR | NPCM_PSPI_CTL1_EIW);
 273
 274         return 0;
 275 }
 276
 277 static int npcm_pspi_unprepare_transfer_hardware(struct spi_master *master)
 278 {
 279         struct npcm_pspi *priv = spi_master_get_devdata(master);
 280
 281         npcm_pspi_irq_disable(priv, NPCM_PSPI_CTL1_EIR | NPCM_PSPI_CTL1_EIW);
 282
 283         return 0;
 284 }
 285
 286 static void npcm_pspi_reset_hw(struct npcm_pspi *priv)
 287 {
 288         regmap_write(priv->rst_regmap, NPCM7XX_IPSRST2_OFFSET,
 289                      NPCM7XX_PSPI1_RESET << priv->id);
 290         regmap_write(priv->rst_regmap, NPCM7XX_IPSRST2_OFFSET, 0x0);
 291 }
 292
 293 static irqreturn_t npcm_pspi_handler(int irq, void *dev_id)
 294 {
 295         struct npcm_pspi *priv = dev_id;
 296         u8 stat;
 297
 298         stat = ioread8(priv->base + NPCM_PSPI_STAT);
 299
 300         if (!priv->tx_buf && !priv->rx_buf)
 301                 return IRQ_NONE;
 302
 303         if (priv->tx_buf) {
 304                 if (stat & NPCM_PSPI_STAT_RBF) {
 305                         ioread8(NPCM_PSPI_DATA + priv->base);
 306                         if (priv->tx_bytes == 0) {
 307                                 npcm_pspi_disable(priv);
 308                                 complete(&priv->xfer_done);
 309                                 return IRQ_HANDLED;
 310                         }
 311                 }
 312
 313                 if ((stat & NPCM_PSPI_STAT_BSY) == 0)
 314                         if (priv->tx_bytes)
 315                                 npcm_pspi_send(priv);
 316         }
 317
 318         if (priv->rx_buf) {
 319                 if (stat & NPCM_PSPI_STAT_RBF) {
 320                         if (!priv->rx_bytes)
 321                                 return IRQ_NONE;
 322
 323                         npcm_pspi_recv(priv);
 324
 325                         if (!priv->rx_bytes) {
 326                                 npcm_pspi_disable(priv);
 327                                 complete(&priv->xfer_done);
 328                                 return IRQ_HANDLED;
 329                         }
 330                 }
 331
 332                 if (((stat & NPCM_PSPI_STAT_BSY) == 0) && !priv->tx_buf)
 333                         iowrite8(0x0, NPCM_PSPI_DATA + priv->base);
 334         }
 335
 336         return IRQ_HANDLED;
 337 }
 338
 339 static int npcm_pspi_probe(struct platform_device *pdev)
 340 {
 341         struct npcm_pspi *priv;
 342         struct spi_master *master;
 343         unsigned long clk_hz;
 344         struct device_node *np = pdev->dev.of_node;
 345         int num_cs, i;
 346         int csgpio;
 347         int irq;
 348         int ret;
 349
 350         num_cs = of_gpio_named_count(np, "cs-gpios");
 351         if (num_cs < 0)
 352                 return num_cs;
 353
 354         pdev->id = of_alias_get_id(np, "spi");
 355         if (pdev->id < 0)
 356                 pdev->id = 0;
 357
 358         master = spi_alloc_master(&pdev->dev, sizeof(*priv));
 359         if (!master)
 360                 return -ENOMEM;
 361
 362         platform_set_drvdata(pdev, master);
 363
 364         priv = spi_master_get_devdata(master);
 365         priv->master = master;
 366         priv->is_save_param = false;
 367         priv->id = pdev->id;
 368
 369         priv->base = devm_platform_ioremap_resource(pdev, 0);
 370         if (IS_ERR(priv->base)) {
 371                 ret = PTR_ERR(priv->base);
 372                 goto out_master_put;
 373         }
 374
 375         priv->clk = devm_clk_get(&pdev->dev, NULL);
 376         if (IS_ERR(priv->clk)) {
 377                 dev_err(&pdev->dev, "failed to get clock\n");
 378                 ret = PTR_ERR(priv->clk);
 379                 goto out_master_put;
 380         }
 381
 382         ret = clk_prepare_enable(priv->clk);
 383         if (ret)
 384                 goto out_master_put;
 385
 386         irq = platform_get_irq(pdev, 0);
 387         if (irq < 0) {
 388                 ret = irq;
 389                 goto out_disable_clk;
 390         }
 391
 392         priv->rst_regmap =
 393                 syscon_regmap_lookup_by_compatible("nuvoton,npcm750-rst");
 394         if (IS_ERR(priv->rst_regmap)) {
 395                 dev_err(&pdev->dev, "failed to find nuvoton,npcm750-rst\n");
 396                 return PTR_ERR(priv->rst_regmap);
 397         }
 398
 399         /* reset SPI-HW block */
 400         npcm_pspi_reset_hw(priv);
 401
 402         ret = devm_request_irq(&pdev->dev, irq, npcm_pspi_handler, 0,
 403                                "npcm-pspi", priv);
 404         if (ret) {
 405                 dev_err(&pdev->dev, "failed to request IRQ\n");
 406                 goto out_disable_clk;
 407         }
 408
 409         init_completion(&priv->xfer_done);
 410
 411         clk_hz = clk_get_rate(priv->clk);
 412
 413         master->max_speed_hz = DIV_ROUND_UP(clk_hz, NPCM_PSPI_MIN_CLK_DIVIDER);
 414         master->min_speed_hz = DIV_ROUND_UP(clk_hz, NPCM_PSPI_MAX_CLK_DIVIDER);
 415         master->mode_bits = SPI_CPHA | SPI_CPOL;
 416         master->dev.of_node = pdev->dev.of_node;
 417         master->bus_num = pdev->id;
 418         master->bits_per_word_mask = SPI_BPW_MASK(8) | SPI_BPW_MASK(16);
 419         master->transfer_one = npcm_pspi_transfer_one;
 420         master->prepare_transfer_hardware =
 421                 npcm_pspi_prepare_transfer_hardware;
 422         master->unprepare_transfer_hardware =
 423                 npcm_pspi_unprepare_transfer_hardware;
 424         master->num_chipselect = num_cs;
 425
 426         for (i = 0; i < num_cs; i++) {
 427                 csgpio = of_get_named_gpio(np, "cs-gpios", i);
 428                 if (csgpio < 0) {
 429                         dev_err(&pdev->dev, "failed to get csgpio#%u\n", i);
 430                         goto out_disable_clk;
 431                 }
 432                 dev_dbg(&pdev->dev, "csgpio#%u = %d\n", i, csgpio);
 433                 ret = devm_gpio_request_one(&pdev->dev, csgpio,
 434                                             GPIOF_OUT_INIT_HIGH, DRIVER_NAME);
 435                 if (ret < 0) {
 436                         dev_err(&pdev->dev,
 437                                 "failed to configure csgpio#%u %d\n"
 438                                 , i, csgpio);
 439                         goto out_disable_clk;
 440                 }
 441         }
 442
 443         /* set to default clock rate */
 444         npcm_pspi_set_baudrate(priv, NPCM_PSPI_DEFAULT_CLK);
 445
 446         ret = devm_spi_register_master(&pdev->dev, master);
 447         if (ret)
 448                 goto out_disable_clk;
 449
 450         pr_info("NPCM Peripheral SPI %d probed\n", pdev->id);
 451
 452         return 0;
 453
 454 out_disable_clk:
 455         clk_disable_unprepare(priv->clk);
 456
 457 out_master_put:
 458         spi_master_put(master);
 459         return ret;
 460 }
 461
 462 static int npcm_pspi_remove(struct platform_device *pdev)
 463 {
 464         struct spi_master *master = platform_get_drvdata(pdev);
 465         struct npcm_pspi *priv = spi_master_get_devdata(master);
 466
 467         npcm_pspi_reset_hw(priv);
 468         clk_disable_unprepare(priv->clk);
 469
 470         return 0;
 471 }
 472
 473 static const struct of_device_id npcm_pspi_match[] = {
 474         { .compatible = "nuvoton,npcm750-pspi", .data = NULL },
 475         {}
 476 };
 477 MODULE_DEVICE_TABLE(of, npcm_pspi_match);
 478
 479 static struct platform_driver npcm_pspi_driver = {
 480         .driver         = {
 481                 .name           = DRIVER_NAME,
 482                 .of_match_table = npcm_pspi_match,
 483         },
 484         .probe          = npcm_pspi_probe,
 485         .remove         = npcm_pspi_remove,
 486 };
 487 module_platform_driver(npcm_pspi_driver);
 488
 489 MODULE_DESCRIPTION("NPCM peripheral SPI Controller driver");
 490 MODULE_AUTHOR("Tomer Maimon <tomer.maimon@nuvoton.com>");
 491 MODULE_LICENSE("GPL v2");
 492