drivers/spi/pic32_spi.c

   1 /*
   2  * Microchip PIC32 SPI controller driver.
   3  *
   4  * Copyright (c) 2015, Microchip Technology Inc.
   5  *      Purna Chandra Mandal <purna.mandal@microchip.com>
   6  *
   7  * SPDX-License-Identifier:     GPL-2.0+
   8  */
   9
  10 #include <common.h>
  11 #include <clk.h>
  12 #include <dm.h>
  13 #include <linux/compat.h>
  14 #include <malloc.h>
  15 #include <spi.h>
  16
  17 #include <asm/types.h>
  18 #include <asm/io.h>
  19 #include <asm/gpio.h>
  20 #include <dt-bindings/clock/microchip,clock.h>
  21 #include <mach/pic32.h>
  22
  23 DECLARE_GLOBAL_DATA_PTR;
  24
  25 /* PIC32 SPI controller registers */
  26 struct pic32_reg_spi {
  27         struct pic32_reg_atomic ctrl;
  28         struct pic32_reg_atomic status;
  29         struct pic32_reg_atomic buf;
  30         struct pic32_reg_atomic baud;
  31         struct pic32_reg_atomic ctrl2;
  32 };
  33
  34 /* Bit fields in SPI Control Register */
  35 #define PIC32_SPI_CTRL_MSTEN    BIT(5) /* Enable SPI Master */
  36 #define PIC32_SPI_CTRL_CKP      BIT(6) /* active low */
  37 #define PIC32_SPI_CTRL_CKE      BIT(8) /* Tx on falling edge */
  38 #define PIC32_SPI_CTRL_SMP      BIT(9) /* Rx at middle or end of tx */
  39 #define PIC32_SPI_CTRL_BPW_MASK 0x03   /* Bits per word */
  40 #define  PIC32_SPI_CTRL_BPW_8           0x0
  41 #define  PIC32_SPI_CTRL_BPW_16          0x1
  42 #define  PIC32_SPI_CTRL_BPW_32          0x2
  43 #define PIC32_SPI_CTRL_BPW_SHIFT        10
  44 #define PIC32_SPI_CTRL_ON       BIT(15) /* Macro enable */
  45 #define PIC32_SPI_CTRL_ENHBUF   BIT(16) /* Enable enhanced buffering */
  46 #define PIC32_SPI_CTRL_MCLKSEL  BIT(23) /* Select SPI Clock src */
  47 #define PIC32_SPI_CTRL_MSSEN    BIT(28) /* SPI macro will drive SS */
  48 #define PIC32_SPI_CTRL_FRMEN    BIT(31) /* Enable framing mode */
  49
  50 /* Bit fields in SPI Status Register */
  51 #define PIC32_SPI_STAT_RX_OV            BIT(6) /* err, s/w needs to clear */
  52 #define PIC32_SPI_STAT_TF_LVL_MASK      0x1f
  53 #define PIC32_SPI_STAT_TF_LVL_SHIFT     16
  54 #define PIC32_SPI_STAT_RF_LVL_MASK      0x1f
  55 #define PIC32_SPI_STAT_RF_LVL_SHIFT     24
  56
  57 /* Bit fields in SPI Baud Register */
  58 #define PIC32_SPI_BAUD_MASK     0x1ff
  59
  60 struct pic32_spi_priv {
  61         struct pic32_reg_spi    *regs;
  62         u32                     fifo_depth; /* FIFO depth in bytes */
  63         u32                     fifo_n_word; /* FIFO depth in words */
  64         struct gpio_desc        cs_gpio;
  65
  66         /* Current SPI slave specific */
  67         ulong                   clk_rate;
  68         u32                     speed_hz; /* spi-clk rate */
  69         int                     mode;
  70
  71         /* Current message/transfer state */
  72         const void              *tx;
  73         const void              *tx_end;
  74         const void              *rx;
  75         const void              *rx_end;
  76         u32                     len;
  77
  78         /* SPI FiFo accessor */
  79         void (*rx_fifo)(struct pic32_spi_priv *);
  80         void (*tx_fifo)(struct pic32_spi_priv *);
  81 };
  82
  83 static inline void pic32_spi_enable(struct pic32_spi_priv *priv)
  84 {
  85         writel(PIC32_SPI_CTRL_ON, &priv->regs->ctrl.set);
  86 }
  87
  88 static inline void pic32_spi_disable(struct pic32_spi_priv *priv)
  89 {
  90         writel(PIC32_SPI_CTRL_ON, &priv->regs->ctrl.clr);
  91 }
  92
  93 static inline u32 pic32_spi_rx_fifo_level(struct pic32_spi_priv *priv)
  94 {
  95         u32 sr = readl(&priv->regs->status.raw);
  96
  97         return (sr >> PIC32_SPI_STAT_RF_LVL_SHIFT) & PIC32_SPI_STAT_RF_LVL_MASK;
  98 }
  99
 100 static inline u32 pic32_spi_tx_fifo_level(struct pic32_spi_priv *priv)
 101 {
 102         u32 sr = readl(&priv->regs->status.raw);
 103
 104         return (sr >> PIC32_SPI_STAT_TF_LVL_SHIFT) & PIC32_SPI_STAT_TF_LVL_MASK;
 105 }
 106
 107 /* Return the max entries we can fill into tx fifo */
 108 static u32 pic32_tx_max(struct pic32_spi_priv *priv, int n_bytes)
 109 {
 110         u32 tx_left, tx_room, rxtx_gap;
 111
 112         tx_left = (priv->tx_end - priv->tx) / n_bytes;
 113         tx_room = priv->fifo_n_word - pic32_spi_tx_fifo_level(priv);
 114
 115         rxtx_gap = (priv->rx_end - priv->rx) - (priv->tx_end - priv->tx);
 116         rxtx_gap /= n_bytes;
 117         return min3(tx_left, tx_room, (u32)(priv->fifo_n_word - rxtx_gap));
 118 }
 119
 120 /* Return the max entries we should read out of rx fifo */
 121 static u32 pic32_rx_max(struct pic32_spi_priv *priv, int n_bytes)
 122 {
 123         u32 rx_left = (priv->rx_end - priv->rx) / n_bytes;
 124
 125         return min_t(u32, rx_left, pic32_spi_rx_fifo_level(priv));
 126 }
 127
 128 #define BUILD_SPI_FIFO_RW(__name, __type, __bwl)                \
 129 static void pic32_spi_rx_##__name(struct pic32_spi_priv *priv)  \
 130 {                                                               \
 131         __type val;                                             \
 132         u32 mx = pic32_rx_max(priv, sizeof(__type));            \
 133                                                                 \
 134         for (; mx; mx--) {                                      \
 135                 val = read##__bwl(&priv->regs->buf.raw);        \
 136                 if (priv->rx_end - priv->len)                   \
 137                         *(__type *)(priv->rx) = val;            \
 138                 priv->rx += sizeof(__type);                     \
 139         }                                                       \
 140 }                                                               \
 141                                                                 \
 142 static void pic32_spi_tx_##__name(struct pic32_spi_priv *priv)  \
 143 {                                                               \
 144         __type val;                                             \
 145         u32 mx = pic32_tx_max(priv, sizeof(__type));            \
 146                                                                 \
 147         for (; mx ; mx--) {                                     \
 148                 val = (__type) ~0U;                             \
 149                 if (priv->tx_end - priv->len)                   \
 150                         val =  *(__type *)(priv->tx);           \
 151                 write##__bwl(val, &priv->regs->buf.raw);        \
 152                 priv->tx += sizeof(__type);                     \
 153         }                                                       \
 154 }
 155 BUILD_SPI_FIFO_RW(byte, u8, b);
 156 BUILD_SPI_FIFO_RW(word, u16, w);
 157 BUILD_SPI_FIFO_RW(dword, u32, l);
 158
 159 static int pic32_spi_set_word_size(struct pic32_spi_priv *priv,
 160                                    unsigned int wordlen)
 161 {
 162         u32 bits_per_word;
 163         u32 val;
 164
 165         switch (wordlen) {
 166         case 8:
 167                 priv->rx_fifo = pic32_spi_rx_byte;
 168                 priv->tx_fifo = pic32_spi_tx_byte;
 169                 bits_per_word = PIC32_SPI_CTRL_BPW_8;
 170                 break;
 171         case 16:
 172                 priv->rx_fifo = pic32_spi_rx_word;
 173                 priv->tx_fifo = pic32_spi_tx_word;
 174                 bits_per_word = PIC32_SPI_CTRL_BPW_16;
 175                 break;
 176         case 32:
 177                 priv->rx_fifo = pic32_spi_rx_dword;
 178                 priv->tx_fifo = pic32_spi_tx_dword;
 179                 bits_per_word = PIC32_SPI_CTRL_BPW_32;
 180                 break;
 181         default:
 182                 printf("pic32-spi: unsupported wordlen\n");
 183                 return -EINVAL;
 184         }
 185
 186         /* set bits-per-word */
 187         val = readl(&priv->regs->ctrl.raw);
 188         val &= ~(PIC32_SPI_CTRL_BPW_MASK << PIC32_SPI_CTRL_BPW_SHIFT);
 189         val |= bits_per_word << PIC32_SPI_CTRL_BPW_SHIFT;
 190         writel(val, &priv->regs->ctrl.raw);
 191
 192         /* calculate maximum number of words fifo can hold */
 193         priv->fifo_n_word = DIV_ROUND_UP(priv->fifo_depth, wordlen / 8);
 194
 195         return 0;
 196 }
 197
 198 static int pic32_spi_claim_bus(struct udevice *slave)
 199 {
 200         struct pic32_spi_priv *priv = dev_get_priv(slave->parent);
 201
 202         /* enable chip */
 203         pic32_spi_enable(priv);
 204
 205         return 0;
 206 }
 207
 208 static int pic32_spi_release_bus(struct udevice *slave)
 209 {
 210         struct pic32_spi_priv *priv = dev_get_priv(slave->parent);
 211
 212         /* disable chip */
 213         pic32_spi_disable(priv);
 214
 215         return 0;
 216 }
 217
 218 static void spi_cs_activate(struct pic32_spi_priv *priv)
 219 {
 220         if (!dm_gpio_is_valid(&priv->cs_gpio))
 221                 return;
 222
 223         dm_gpio_set_value(&priv->cs_gpio, 1);
 224 }
 225
 226 static void spi_cs_deactivate(struct pic32_spi_priv *priv)
 227 {
 228         if (!dm_gpio_is_valid(&priv->cs_gpio))
 229                 return;
 230
 231         dm_gpio_set_value(&priv->cs_gpio, 0);
 232 }
 233
 234 static int pic32_spi_xfer(struct udevice *slave, unsigned int bitlen,
 235                           const void *tx_buf, void *rx_buf,
 236                           unsigned long flags)
 237 {
 238         struct dm_spi_slave_platdata *slave_plat;
 239         struct udevice *bus = slave->parent;
 240         struct pic32_spi_priv *priv;
 241         int len = bitlen / 8;
 242         int ret = 0;
 243         ulong tbase;
 244
 245         priv = dev_get_priv(bus);
 246         slave_plat = dev_get_parent_platdata(slave);
 247
 248         debug("spi_xfer: bus:%i cs:%i flags:%lx\n",
 249               bus->seq, slave_plat->cs, flags);
 250         debug("msg tx %p, rx %p submitted of %d byte(s)\n",
 251               tx_buf, rx_buf, len);
 252
 253         /* assert cs */
 254         if (flags & SPI_XFER_BEGIN)
 255                 spi_cs_activate(priv);
 256
 257         /* set current transfer information */
 258         priv->tx = tx_buf;
 259         priv->rx = rx_buf;
 260         priv->tx_end = priv->tx + len;
 261         priv->rx_end = priv->rx + len;
 262         priv->len = len;
 263
 264         /* transact by polling */
 265         tbase = get_timer(0);
 266         for (;;) {
 267                 priv->tx_fifo(priv);
 268                 priv->rx_fifo(priv);
 269
 270                 /* received sufficient data */
 271                 if (priv->rx >= priv->rx_end) {
 272                         ret = 0;
 273                         break;
 274                 }
 275
 276                 if (get_timer(tbase) > 5 * CONFIG_SYS_HZ) {
 277                         printf("pic32_spi: error, xfer timedout.\n");
 278                         flags |= SPI_XFER_END;
 279                         ret = -ETIMEDOUT;
 280                         break;
 281                 }
 282         }
 283
 284         /* deassert cs */
 285         if (flags & SPI_XFER_END)
 286                 spi_cs_deactivate(priv);
 287
 288         return ret;
 289 }
 290
 291 static int pic32_spi_set_speed(struct udevice *bus, uint speed)
 292 {
 293         struct pic32_spi_priv *priv = dev_get_priv(bus);
 294         u32 div;
 295
 296         debug("%s: %s, speed %u\n", __func__, bus->name, speed);
 297
 298         /* div = [clk_in / (2 * spi_clk)] - 1 */
 299         div = (priv->clk_rate / 2 / speed) - 1;
 300         div &= PIC32_SPI_BAUD_MASK;
 301         writel(div, &priv->regs->baud.raw);
 302
 303         priv->speed_hz = speed;
 304
 305         return 0;
 306 }
 307
 308 static int pic32_spi_set_mode(struct udevice *bus, uint mode)
 309 {
 310         struct pic32_spi_priv *priv = dev_get_priv(bus);
 311         u32 val;
 312
 313         debug("%s: %s, mode %d\n", __func__, bus->name, mode);
 314
 315         /* set spi-clk mode */
 316         val = readl(&priv->regs->ctrl.raw);
 317         /* HIGH when idle */
 318         if (mode & SPI_CPOL)
 319                 val |= PIC32_SPI_CTRL_CKP;
 320         else
 321                 val &= ~PIC32_SPI_CTRL_CKP;
 322
 323         /* TX at idle-to-active clk transition */
 324         if (mode & SPI_CPHA)
 325                 val &= ~PIC32_SPI_CTRL_CKE;
 326         else
 327                 val |= PIC32_SPI_CTRL_CKE;
 328
 329         /* RX at end of tx */
 330         val |= PIC32_SPI_CTRL_SMP;
 331         writel(val, &priv->regs->ctrl.raw);
 332
 333         priv->mode = mode;
 334
 335         return 0;
 336 }
 337
 338 static int pic32_spi_set_wordlen(struct udevice *slave, unsigned int wordlen)
 339 {
 340         struct pic32_spi_priv *priv = dev_get_priv(slave->parent);
 341
 342         return pic32_spi_set_word_size(priv, wordlen);
 343 }
 344
 345 static void pic32_spi_hw_init(struct pic32_spi_priv *priv)
 346 {
 347         u32 val;
 348
 349         /* disable module */
 350         pic32_spi_disable(priv);
 351
 352         val = readl(&priv->regs->ctrl);
 353
 354         /* enable enhanced fifo of 128bit deep */
 355         val |= PIC32_SPI_CTRL_ENHBUF;
 356         priv->fifo_depth = 16;
 357
 358         /* disable framing mode */
 359         val &= ~PIC32_SPI_CTRL_FRMEN;
 360
 361         /* enable master mode */
 362         val |= PIC32_SPI_CTRL_MSTEN;
 363
 364         /* select clk source */
 365         val &= ~PIC32_SPI_CTRL_MCLKSEL;
 366
 367         /* set manual /CS mode */
 368         val &= ~PIC32_SPI_CTRL_MSSEN;
 369
 370         writel(val, &priv->regs->ctrl);
 371
 372         /* clear rx overflow indicator */
 373         writel(PIC32_SPI_STAT_RX_OV, &priv->regs->status.clr);
 374 }
 375
 376 static int pic32_spi_probe(struct udevice *bus)
 377 {
 378         struct pic32_spi_priv *priv = dev_get_priv(bus);
 379         struct dm_spi_bus *dm_spi = dev_get_uclass_priv(bus);
 380         int node = dev_of_offset(bus);
 381         struct udevice *clkdev;
 382         fdt_addr_t addr;
 383         fdt_size_t size;
 384         int ret;
 385
 386         debug("%s: %d, bus: %i\n", __func__, __LINE__, bus->seq);
 387         addr = fdtdec_get_addr_size(gd->fdt_blob, node, "reg", &size);
 388         if (addr == FDT_ADDR_T_NONE)
 389                 return -EINVAL;
 390
 391         priv->regs = ioremap(addr, size);
 392         if (!priv->regs)
 393                 return -EINVAL;
 394
 395         dm_spi->max_hz = fdtdec_get_int(gd->fdt_blob, node, "spi-max-frequency",
 396                                         250000000);
 397         /* get clock rate */
 398         ret = clk_get_by_index(bus, 0, &clkdev);
 399         if (ret < 0) {
 400                 printf("pic32-spi: error, clk not found\n");
 401                 return ret;
 402         }
 403         priv->clk_rate = clk_get_periph_rate(clkdev, ret);
 404
 405         /* initialize HW */
 406         pic32_spi_hw_init(priv);
 407
 408         /* set word len */
 409         pic32_spi_set_word_size(priv, SPI_DEFAULT_WORDLEN);
 410
 411         /* PIC32 SPI controller can automatically drive /CS during transfer
 412          * depending on fifo fill-level. /CS will stay asserted as long as
 413          * TX fifo is non-empty, else will be deasserted confirming completion
 414          * of the ongoing transfer. To avoid this sort of error we will drive
 415          * /CS manually by toggling cs-gpio pins.
 416          */
 417         ret = gpio_request_by_name_nodev(offset_to_ofnode(node), "cs-gpios", 0,
 418                                          &priv->cs_gpio, GPIOD_IS_OUT);
 419         if (ret) {
 420                 printf("pic32-spi: error, cs-gpios not found\n");
 421                 return ret;
 422         }
 423
 424         return 0;
 425 }
 426
 427 static const struct dm_spi_ops pic32_spi_ops = {
 428         .claim_bus      = pic32_spi_claim_bus,
 429         .release_bus    = pic32_spi_release_bus,
 430         .xfer           = pic32_spi_xfer,
 431         .set_speed      = pic32_spi_set_speed,
 432         .set_mode       = pic32_spi_set_mode,
 433         .set_wordlen    = pic32_spi_set_wordlen,
 434 };
 435
 436 static const struct udevice_id pic32_spi_ids[] = {
 437         { .compatible = "microchip,pic32mzda-spi" },
 438         { }
 439 };
 440
 441 U_BOOT_DRIVER(pic32_spi) = {
 442         .name           = "pic32_spi",
 443         .id             = UCLASS_SPI,
 444         .of_match       = pic32_spi_ids,
 445         .ops            = &pic32_spi_ops,
 446         .priv_auto_alloc_size = sizeof(struct pic32_spi_priv),
 447         .probe          = pic32_spi_probe,
 448 };