drivers/spi/pic32_spi.c

   1 // SPDX-License-Identifier: GPL-2.0+
   2 /*
   3  * Microchip PIC32 SPI controller driver.
   4  *
   5  * Copyright (c) 2015, Microchip Technology Inc.
   6  *      Purna Chandra Mandal <purna.mandal@microchip.com>
   7  */
   8
   9 #include <common.h>
  10 #include <clk.h>
  11 #include <dm.h>
  12 #include <linux/compat.h>
  13 #include <malloc.h>
  14 #include <spi.h>
  15
  16 #include <asm/types.h>
  17 #include <asm/io.h>
  18 #include <asm/gpio.h>
  19 #include <dt-bindings/clock/microchip,clock.h>
  20 #include <mach/pic32.h>
  21
  22 DECLARE_GLOBAL_DATA_PTR;
  23
  24 /* PIC32 SPI controller registers */
  25 struct pic32_reg_spi {
  26         struct pic32_reg_atomic ctrl;
  27         struct pic32_reg_atomic status;
  28         struct pic32_reg_atomic buf;
  29         struct pic32_reg_atomic baud;
  30         struct pic32_reg_atomic ctrl2;
  31 };
  32
  33 /* Bit fields in SPI Control Register */
  34 #define PIC32_SPI_CTRL_MSTEN    BIT(5) /* Enable SPI Master */
  35 #define PIC32_SPI_CTRL_CKP      BIT(6) /* active low */
  36 #define PIC32_SPI_CTRL_CKE      BIT(8) /* Tx on falling edge */
  37 #define PIC32_SPI_CTRL_SMP      BIT(9) /* Rx at middle or end of tx */
  38 #define PIC32_SPI_CTRL_BPW_MASK 0x03   /* Bits per word */
  39 #define  PIC32_SPI_CTRL_BPW_8           0x0
  40 #define  PIC32_SPI_CTRL_BPW_16          0x1
  41 #define  PIC32_SPI_CTRL_BPW_32          0x2
  42 #define PIC32_SPI_CTRL_BPW_SHIFT        10
  43 #define PIC32_SPI_CTRL_ON       BIT(15) /* Macro enable */
  44 #define PIC32_SPI_CTRL_ENHBUF   BIT(16) /* Enable enhanced buffering */
  45 #define PIC32_SPI_CTRL_MCLKSEL  BIT(23) /* Select SPI Clock src */
  46 #define PIC32_SPI_CTRL_MSSEN    BIT(28) /* SPI macro will drive SS */
  47 #define PIC32_SPI_CTRL_FRMEN    BIT(31) /* Enable framing mode */
  48
  49 /* Bit fields in SPI Status Register */
  50 #define PIC32_SPI_STAT_RX_OV            BIT(6) /* err, s/w needs to clear */
  51 #define PIC32_SPI_STAT_TF_LVL_MASK      0x1f
  52 #define PIC32_SPI_STAT_TF_LVL_SHIFT     16
  53 #define PIC32_SPI_STAT_RF_LVL_MASK      0x1f
  54 #define PIC32_SPI_STAT_RF_LVL_SHIFT     24
  55
  56 /* Bit fields in SPI Baud Register */
  57 #define PIC32_SPI_BAUD_MASK     0x1ff
  58
  59 struct pic32_spi_priv {
  60         struct pic32_reg_spi    *regs;
  61         u32                     fifo_depth; /* FIFO depth in bytes */
  62         u32                     fifo_n_word; /* FIFO depth in words */
  63         struct gpio_desc        cs_gpio;
  64
  65         /* Current SPI slave specific */
  66         ulong                   clk_rate;
  67         u32                     speed_hz; /* spi-clk rate */
  68         int                     mode;
  69
  70         /* Current message/transfer state */
  71         const void              *tx;
  72         const void              *tx_end;
  73         const void              *rx;
  74         const void              *rx_end;
  75         u32                     len;
  76
  77         /* SPI FiFo accessor */
  78         void (*rx_fifo)(struct pic32_spi_priv *);
  79         void (*tx_fifo)(struct pic32_spi_priv *);
  80 };
  81
  82 static inline void pic32_spi_enable(struct pic32_spi_priv *priv)
  83 {
  84         writel(PIC32_SPI_CTRL_ON, &priv->regs->ctrl.set);
  85 }
  86
  87 static inline void pic32_spi_disable(struct pic32_spi_priv *priv)
  88 {
  89         writel(PIC32_SPI_CTRL_ON, &priv->regs->ctrl.clr);
  90 }
  91
  92 static inline u32 pic32_spi_rx_fifo_level(struct pic32_spi_priv *priv)
  93 {
  94         u32 sr = readl(&priv->regs->status.raw);
  95
  96         return (sr >> PIC32_SPI_STAT_RF_LVL_SHIFT) & PIC32_SPI_STAT_RF_LVL_MASK;
  97 }
  98
  99 static inline u32 pic32_spi_tx_fifo_level(struct pic32_spi_priv *priv)
 100 {
 101         u32 sr = readl(&priv->regs->status.raw);
 102
 103         return (sr >> PIC32_SPI_STAT_TF_LVL_SHIFT) & PIC32_SPI_STAT_TF_LVL_MASK;
 104 }
 105
 106 /* Return the max entries we can fill into tx fifo */
 107 static u32 pic32_tx_max(struct pic32_spi_priv *priv, int n_bytes)
 108 {
 109         u32 tx_left, tx_room, rxtx_gap;
 110
 111         tx_left = (priv->tx_end - priv->tx) / n_bytes;
 112         tx_room = priv->fifo_n_word - pic32_spi_tx_fifo_level(priv);
 113
 114         rxtx_gap = (priv->rx_end - priv->rx) - (priv->tx_end - priv->tx);
 115         rxtx_gap /= n_bytes;
 116         return min3(tx_left, tx_room, (u32)(priv->fifo_n_word - rxtx_gap));
 117 }
 118
 119 /* Return the max entries we should read out of rx fifo */
 120 static u32 pic32_rx_max(struct pic32_spi_priv *priv, int n_bytes)
 121 {
 122         u32 rx_left = (priv->rx_end - priv->rx) / n_bytes;
 123
 124         return min_t(u32, rx_left, pic32_spi_rx_fifo_level(priv));
 125 }
 126
 127 #define BUILD_SPI_FIFO_RW(__name, __type, __bwl)                \
 128 static void pic32_spi_rx_##__name(struct pic32_spi_priv *priv)  \
 129 {                                                               \
 130         __type val;                                             \
 131         u32 mx = pic32_rx_max(priv, sizeof(__type));            \
 132                                                                 \
 133         for (; mx; mx--) {                                      \
 134                 val = read##__bwl(&priv->regs->buf.raw);        \
 135                 if (priv->rx_end - priv->len)                   \
 136                         *(__type *)(priv->rx) = val;            \
 137                 priv->rx += sizeof(__type);                     \
 138         }                                                       \
 139 }                                                               \
 140                                                                 \
 141 static void pic32_spi_tx_##__name(struct pic32_spi_priv *priv)  \
 142 {                                                               \
 143         __type val;                                             \
 144         u32 mx = pic32_tx_max(priv, sizeof(__type));            \
 145                                                                 \
 146         for (; mx ; mx--) {                                     \
 147                 val = (__type) ~0U;                             \
 148                 if (priv->tx_end - priv->len)                   \
 149                         val =  *(__type *)(priv->tx);           \
 150                 write##__bwl(val, &priv->regs->buf.raw);        \
 151                 priv->tx += sizeof(__type);                     \
 152         }                                                       \
 153 }
 154 BUILD_SPI_FIFO_RW(byte, u8, b);
 155 BUILD_SPI_FIFO_RW(word, u16, w);
 156 BUILD_SPI_FIFO_RW(dword, u32, l);
 157
 158 static int pic32_spi_set_word_size(struct pic32_spi_priv *priv,
 159                                    unsigned int wordlen)
 160 {
 161         u32 bits_per_word;
 162         u32 val;
 163
 164         switch (wordlen) {
 165         case 8:
 166                 priv->rx_fifo = pic32_spi_rx_byte;
 167                 priv->tx_fifo = pic32_spi_tx_byte;
 168                 bits_per_word = PIC32_SPI_CTRL_BPW_8;
 169                 break;
 170         case 16:
 171                 priv->rx_fifo = pic32_spi_rx_word;
 172                 priv->tx_fifo = pic32_spi_tx_word;
 173                 bits_per_word = PIC32_SPI_CTRL_BPW_16;
 174                 break;
 175         case 32:
 176                 priv->rx_fifo = pic32_spi_rx_dword;
 177                 priv->tx_fifo = pic32_spi_tx_dword;
 178                 bits_per_word = PIC32_SPI_CTRL_BPW_32;
 179                 break;
 180         default:
 181                 printf("pic32-spi: unsupported wordlen\n");
 182                 return -EINVAL;
 183         }
 184
 185         /* set bits-per-word */
 186         val = readl(&priv->regs->ctrl.raw);
 187         val &= ~(PIC32_SPI_CTRL_BPW_MASK << PIC32_SPI_CTRL_BPW_SHIFT);
 188         val |= bits_per_word << PIC32_SPI_CTRL_BPW_SHIFT;
 189         writel(val, &priv->regs->ctrl.raw);
 190
 191         /* calculate maximum number of words fifo can hold */
 192         priv->fifo_n_word = DIV_ROUND_UP(priv->fifo_depth, wordlen / 8);
 193
 194         return 0;
 195 }
 196
 197 static int pic32_spi_claim_bus(struct udevice *slave)
 198 {
 199         struct pic32_spi_priv *priv = dev_get_priv(slave->parent);
 200
 201         /* enable chip */
 202         pic32_spi_enable(priv);
 203
 204         return 0;
 205 }
 206
 207 static int pic32_spi_release_bus(struct udevice *slave)
 208 {
 209         struct pic32_spi_priv *priv = dev_get_priv(slave->parent);
 210
 211         /* disable chip */
 212         pic32_spi_disable(priv);
 213
 214         return 0;
 215 }
 216
 217 static void spi_cs_activate(struct pic32_spi_priv *priv)
 218 {
 219         if (!dm_gpio_is_valid(&priv->cs_gpio))
 220                 return;
 221
 222         dm_gpio_set_value(&priv->cs_gpio, 1);
 223 }
 224
 225 static void spi_cs_deactivate(struct pic32_spi_priv *priv)
 226 {
 227         if (!dm_gpio_is_valid(&priv->cs_gpio))
 228                 return;
 229
 230         dm_gpio_set_value(&priv->cs_gpio, 0);
 231 }
 232
 233 static int pic32_spi_xfer(struct udevice *slave, unsigned int bitlen,
 234                           const void *tx_buf, void *rx_buf,
 235                           unsigned long flags)
 236 {
 237         struct dm_spi_slave_platdata *slave_plat;
 238         struct udevice *bus = slave->parent;
 239         struct pic32_spi_priv *priv;
 240         int len = bitlen / 8;
 241         int ret = 0;
 242         ulong tbase;
 243
 244         priv = dev_get_priv(bus);
 245         slave_plat = dev_get_parent_platdata(slave);
 246
 247         debug("spi_xfer: bus:%i cs:%i flags:%lx\n",
 248               bus->seq, slave_plat->cs, flags);
 249         debug("msg tx %p, rx %p submitted of %d byte(s)\n",
 250               tx_buf, rx_buf, len);
 251
 252         /* assert cs */
 253         if (flags & SPI_XFER_BEGIN)
 254                 spi_cs_activate(priv);
 255
 256         /* set current transfer information */
 257         priv->tx = tx_buf;
 258         priv->rx = rx_buf;
 259         priv->tx_end = priv->tx + len;
 260         priv->rx_end = priv->rx + len;
 261         priv->len = len;
 262
 263         /* transact by polling */
 264         tbase = get_timer(0);
 265         for (;;) {
 266                 priv->tx_fifo(priv);
 267                 priv->rx_fifo(priv);
 268
 269                 /* received sufficient data */
 270                 if (priv->rx >= priv->rx_end) {
 271                         ret = 0;
 272                         break;
 273                 }
 274
 275                 if (get_timer(tbase) > 5 * CONFIG_SYS_HZ) {
 276                         printf("pic32_spi: error, xfer timedout.\n");
 277                         flags |= SPI_XFER_END;
 278                         ret = -ETIMEDOUT;
 279                         break;
 280                 }
 281         }
 282
 283         /* deassert cs */
 284         if (flags & SPI_XFER_END)
 285                 spi_cs_deactivate(priv);
 286
 287         return ret;
 288 }
 289
 290 static int pic32_spi_set_speed(struct udevice *bus, uint speed)
 291 {
 292         struct pic32_spi_priv *priv = dev_get_priv(bus);
 293         u32 div;
 294
 295         debug("%s: %s, speed %u\n", __func__, bus->name, speed);
 296
 297         /* div = [clk_in / (2 * spi_clk)] - 1 */
 298         div = (priv->clk_rate / 2 / speed) - 1;
 299         div &= PIC32_SPI_BAUD_MASK;
 300         writel(div, &priv->regs->baud.raw);
 301
 302         priv->speed_hz = speed;
 303
 304         return 0;
 305 }
 306
 307 static int pic32_spi_set_mode(struct udevice *bus, uint mode)
 308 {
 309         struct pic32_spi_priv *priv = dev_get_priv(bus);
 310         u32 val;
 311
 312         debug("%s: %s, mode %d\n", __func__, bus->name, mode);
 313
 314         /* set spi-clk mode */
 315         val = readl(&priv->regs->ctrl.raw);
 316         /* HIGH when idle */
 317         if (mode & SPI_CPOL)
 318                 val |= PIC32_SPI_CTRL_CKP;
 319         else
 320                 val &= ~PIC32_SPI_CTRL_CKP;
 321
 322         /* TX at idle-to-active clk transition */
 323         if (mode & SPI_CPHA)
 324                 val &= ~PIC32_SPI_CTRL_CKE;
 325         else
 326                 val |= PIC32_SPI_CTRL_CKE;
 327
 328         /* RX at end of tx */
 329         val |= PIC32_SPI_CTRL_SMP;
 330         writel(val, &priv->regs->ctrl.raw);
 331
 332         priv->mode = mode;
 333
 334         return 0;
 335 }
 336
 337 static int pic32_spi_set_wordlen(struct udevice *slave, unsigned int wordlen)
 338 {
 339         struct pic32_spi_priv *priv = dev_get_priv(slave->parent);
 340
 341         return pic32_spi_set_word_size(priv, wordlen);
 342 }
 343
 344 static void pic32_spi_hw_init(struct pic32_spi_priv *priv)
 345 {
 346         u32 val;
 347
 348         /* disable module */
 349         pic32_spi_disable(priv);
 350
 351         val = readl(&priv->regs->ctrl);
 352
 353         /* enable enhanced fifo of 128bit deep */
 354         val |= PIC32_SPI_CTRL_ENHBUF;
 355         priv->fifo_depth = 16;
 356
 357         /* disable framing mode */
 358         val &= ~PIC32_SPI_CTRL_FRMEN;
 359
 360         /* enable master mode */
 361         val |= PIC32_SPI_CTRL_MSTEN;
 362
 363         /* select clk source */
 364         val &= ~PIC32_SPI_CTRL_MCLKSEL;
 365
 366         /* set manual /CS mode */
 367         val &= ~PIC32_SPI_CTRL_MSSEN;
 368
 369         writel(val, &priv->regs->ctrl);
 370
 371         /* clear rx overflow indicator */
 372         writel(PIC32_SPI_STAT_RX_OV, &priv->regs->status.clr);
 373 }
 374
 375 static int pic32_spi_probe(struct udevice *bus)
 376 {
 377         struct pic32_spi_priv *priv = dev_get_priv(bus);
 378         struct dm_spi_bus *dm_spi = dev_get_uclass_priv(bus);
 379         int node = dev_of_offset(bus);
 380         struct udevice *clkdev;
 381         fdt_addr_t addr;
 382         fdt_size_t size;
 383         int ret;
 384
 385         debug("%s: %d, bus: %i\n", __func__, __LINE__, bus->seq);
 386         addr = fdtdec_get_addr_size(gd->fdt_blob, node, "reg", &size);
 387         if (addr == FDT_ADDR_T_NONE)
 388                 return -EINVAL;
 389
 390         priv->regs = ioremap(addr, size);
 391         if (!priv->regs)
 392                 return -EINVAL;
 393
 394         dm_spi->max_hz = fdtdec_get_int(gd->fdt_blob, node, "spi-max-frequency",
 395                                         250000000);
 396         /* get clock rate */
 397         ret = clk_get_by_index(bus, 0, &clkdev);
 398         if (ret < 0) {
 399                 printf("pic32-spi: error, clk not found\n");
 400                 return ret;
 401         }
 402         priv->clk_rate = clk_get_periph_rate(clkdev, ret);
 403
 404         /* initialize HW */
 405         pic32_spi_hw_init(priv);
 406
 407         /* set word len */
 408         pic32_spi_set_word_size(priv, SPI_DEFAULT_WORDLEN);
 409
 410         /* PIC32 SPI controller can automatically drive /CS during transfer
 411          * depending on fifo fill-level. /CS will stay asserted as long as
 412          * TX fifo is non-empty, else will be deasserted confirming completion
 413          * of the ongoing transfer. To avoid this sort of error we will drive
 414          * /CS manually by toggling cs-gpio pins.
 415          */
 416         ret = gpio_request_by_name_nodev(offset_to_ofnode(node), "cs-gpios", 0,
 417                                          &priv->cs_gpio, GPIOD_IS_OUT);
 418         if (ret) {
 419                 printf("pic32-spi: error, cs-gpios not found\n");
 420                 return ret;
 421         }
 422
 423         return 0;
 424 }
 425
 426 static const struct dm_spi_ops pic32_spi_ops = {
 427         .claim_bus      = pic32_spi_claim_bus,
 428         .release_bus    = pic32_spi_release_bus,
 429         .xfer           = pic32_spi_xfer,
 430         .set_speed      = pic32_spi_set_speed,
 431         .set_mode       = pic32_spi_set_mode,
 432         .set_wordlen    = pic32_spi_set_wordlen,
 433 };
 434
 435 static const struct udevice_id pic32_spi_ids[] = {
 436         { .compatible = "microchip,pic32mzda-spi" },
 437         { }
 438 };
 439
 440 U_BOOT_DRIVER(pic32_spi) = {
 441         .name           = "pic32_spi",
 442         .id             = UCLASS_SPI,
 443         .of_match       = pic32_spi_ids,
 444         .ops            = &pic32_spi_ops,
 445         .priv_auto_alloc_size = sizeof(struct pic32_spi_priv),
 446         .probe          = pic32_spi_probe,
 447 };