drivers/spi/spi-xilinx.c

   1 /*
   2  * Xilinx SPI controller driver (master mode only)
   3  *
   4  * Author: MontaVista Software, Inc.
   5  *      source@mvista.com
   6  *
   7  * Copyright (c) 2010 Secret Lab Technologies, Ltd.
   8  * Copyright (c) 2009 Intel Corporation
   9  * 2002-2007 (c) MontaVista Software, Inc.
  10
  11  * This program is free software; you can redistribute it and/or modify
  12  * it under the terms of the GNU General Public License version 2 as
  13  * published by the Free Software Foundation.
  14  */
  15
  16 #include <linux/module.h>
  17 #include <linux/init.h>
  18 #include <linux/interrupt.h>
  19 #include <linux/of.h>
  20 #include <linux/platform_device.h>
  21 #include <linux/spi/spi.h>
  22 #include <linux/spi/spi_bitbang.h>
  23 #include <linux/spi/xilinx_spi.h>
  24 #include <linux/io.h>
  25
  26 #define XILINX_SPI_NAME "xilinx_spi"
  27
  28 /* Register definitions as per "OPB Serial Peripheral Interface (SPI) (v1.00e)
  29  * Product Specification", DS464
  30  */
  31 #define XSPI_CR_OFFSET          0x60    /* Control Register */
  32
  33 #define XSPI_CR_LOOP            0x01
  34 #define XSPI_CR_ENABLE          0x02
  35 #define XSPI_CR_MASTER_MODE     0x04
  36 #define XSPI_CR_CPOL            0x08
  37 #define XSPI_CR_CPHA            0x10
  38 #define XSPI_CR_MODE_MASK       (XSPI_CR_CPHA | XSPI_CR_CPOL)
  39 #define XSPI_CR_TXFIFO_RESET    0x20
  40 #define XSPI_CR_RXFIFO_RESET    0x40
  41 #define XSPI_CR_MANUAL_SSELECT  0x80
  42 #define XSPI_CR_TRANS_INHIBIT   0x100
  43 #define XSPI_CR_LSB_FIRST       0x200
  44
  45 #define XSPI_SR_OFFSET          0x64    /* Status Register */
  46
  47 #define XSPI_SR_RX_EMPTY_MASK   0x01    /* Receive FIFO is empty */
  48 #define XSPI_SR_RX_FULL_MASK    0x02    /* Receive FIFO is full */
  49 #define XSPI_SR_TX_EMPTY_MASK   0x04    /* Transmit FIFO is empty */
  50 #define XSPI_SR_TX_FULL_MASK    0x08    /* Transmit FIFO is full */
  51 #define XSPI_SR_MODE_FAULT_MASK 0x10    /* Mode fault error */
  52
  53 #define XSPI_TXD_OFFSET         0x68    /* Data Transmit Register */
  54 #define XSPI_RXD_OFFSET         0x6c    /* Data Receive Register */
  55
  56 #define XSPI_SSR_OFFSET         0x70    /* 32-bit Slave Select Register */
  57
  58 /* Register definitions as per "OPB IPIF (v3.01c) Product Specification", DS414
  59  * IPIF registers are 32 bit
  60  */
  61 #define XIPIF_V123B_DGIER_OFFSET        0x1c    /* IPIF global int enable reg */
  62 #define XIPIF_V123B_GINTR_ENABLE        0x80000000
  63
  64 #define XIPIF_V123B_IISR_OFFSET         0x20    /* IPIF interrupt status reg */
  65 #define XIPIF_V123B_IIER_OFFSET         0x28    /* IPIF interrupt enable reg */
  66
  67 #define XSPI_INTR_MODE_FAULT            0x01    /* Mode fault error */
  68 #define XSPI_INTR_SLAVE_MODE_FAULT      0x02    /* Selected as slave while
  69                                                  * disabled */
  70 #define XSPI_INTR_TX_EMPTY              0x04    /* TxFIFO is empty */
  71 #define XSPI_INTR_TX_UNDERRUN           0x08    /* TxFIFO was underrun */
  72 #define XSPI_INTR_RX_FULL               0x10    /* RxFIFO is full */
  73 #define XSPI_INTR_RX_OVERRUN            0x20    /* RxFIFO was overrun */
  74 #define XSPI_INTR_TX_HALF_EMPTY         0x40    /* TxFIFO is half empty */
  75
  76 #define XIPIF_V123B_RESETR_OFFSET       0x40    /* IPIF reset register */
  77 #define XIPIF_V123B_RESET_MASK          0x0a    /* the value to write */
  78
  79 struct xilinx_spi {
  80         /* bitbang has to be first */
  81         struct spi_bitbang bitbang;
  82         struct completion done;
  83         struct resource mem; /* phys mem */
  84         void __iomem    *regs;  /* virt. address of the control registers */
  85
  86         u32             irq;
  87
  88         u8 *rx_ptr;             /* pointer in the Tx buffer */
  89         const u8 *tx_ptr;       /* pointer in the Rx buffer */
  90         int remaining_bytes;    /* the number of bytes left to transfer */
  91         u8 bits_per_word;
  92         unsigned int (*read_fn) (void __iomem *);
  93         void (*write_fn) (u32, void __iomem *);
  94         void (*tx_fn) (struct xilinx_spi *);
  95         void (*rx_fn) (struct xilinx_spi *);
  96 };
  97
  98 static void xspi_write32(u32 val, void __iomem *addr)
  99 {
 100         iowrite32(val, addr);
 101 }
 102
 103 static unsigned int xspi_read32(void __iomem *addr)
 104 {
 105         return ioread32(addr);
 106 }
 107
 108 static void xspi_write32_be(u32 val, void __iomem *addr)
 109 {
 110         iowrite32be(val, addr);
 111 }
 112
 113 static unsigned int xspi_read32_be(void __iomem *addr)
 114 {
 115         return ioread32be(addr);
 116 }
 117
 118 static void xspi_tx8(struct xilinx_spi *xspi)
 119 {
 120         xspi->write_fn(*xspi->tx_ptr, xspi->regs + XSPI_TXD_OFFSET);
 121         xspi->tx_ptr++;
 122 }
 123
 124 static void xspi_tx16(struct xilinx_spi *xspi)
 125 {
 126         xspi->write_fn(*(u16 *)(xspi->tx_ptr), xspi->regs + XSPI_TXD_OFFSET);
 127         xspi->tx_ptr += 2;
 128 }
 129
 130 static void xspi_tx32(struct xilinx_spi *xspi)
 131 {
 132         xspi->write_fn(*(u32 *)(xspi->tx_ptr), xspi->regs + XSPI_TXD_OFFSET);
 133         xspi->tx_ptr += 4;
 134 }
 135
 136 static void xspi_rx8(struct xilinx_spi *xspi)
 137 {
 138         u32 data = xspi->read_fn(xspi->regs + XSPI_RXD_OFFSET);
 139         if (xspi->rx_ptr) {
 140                 *xspi->rx_ptr = data & 0xff;
 141                 xspi->rx_ptr++;
 142         }
 143 }
 144
 145 static void xspi_rx16(struct xilinx_spi *xspi)
 146 {
 147         u32 data = xspi->read_fn(xspi->regs + XSPI_RXD_OFFSET);
 148         if (xspi->rx_ptr) {
 149                 *(u16 *)(xspi->rx_ptr) = data & 0xffff;
 150                 xspi->rx_ptr += 2;
 151         }
 152 }
 153
 154 static void xspi_rx32(struct xilinx_spi *xspi)
 155 {
 156         u32 data = xspi->read_fn(xspi->regs + XSPI_RXD_OFFSET);
 157         if (xspi->rx_ptr) {
 158                 *(u32 *)(xspi->rx_ptr) = data;
 159                 xspi->rx_ptr += 4;
 160         }
 161 }
 162
 163 static void xspi_init_hw(struct xilinx_spi *xspi)
 164 {
 165         void __iomem *regs_base = xspi->regs;
 166
 167         /* Reset the SPI device */
 168         xspi->write_fn(XIPIF_V123B_RESET_MASK,
 169                 regs_base + XIPIF_V123B_RESETR_OFFSET);
 170         /* Disable all the interrupts just in case */
 171         xspi->write_fn(0, regs_base + XIPIF_V123B_IIER_OFFSET);
 172         /* Enable the global IPIF interrupt */
 173         xspi->write_fn(XIPIF_V123B_GINTR_ENABLE,
 174                 regs_base + XIPIF_V123B_DGIER_OFFSET);
 175         /* Deselect the slave on the SPI bus */
 176         xspi->write_fn(0xffff, regs_base + XSPI_SSR_OFFSET);
 177         /* Disable the transmitter, enable Manual Slave Select Assertion,
 178          * put SPI controller into master mode, and enable it */
 179         xspi->write_fn(XSPI_CR_TRANS_INHIBIT | XSPI_CR_MANUAL_SSELECT |
 180                 XSPI_CR_MASTER_MODE | XSPI_CR_ENABLE | XSPI_CR_TXFIFO_RESET |
 181                 XSPI_CR_RXFIFO_RESET, regs_base + XSPI_CR_OFFSET);
 182 }
 183
 184 static void xilinx_spi_chipselect(struct spi_device *spi, int is_on)
 185 {
 186         struct xilinx_spi *xspi = spi_master_get_devdata(spi->master);
 187
 188         if (is_on == BITBANG_CS_INACTIVE) {
 189                 /* Deselect the slave on the SPI bus */
 190                 xspi->write_fn(0xffff, xspi->regs + XSPI_SSR_OFFSET);
 191         } else if (is_on == BITBANG_CS_ACTIVE) {
 192                 /* Set the SPI clock phase and polarity */
 193                 u16 cr = xspi->read_fn(xspi->regs + XSPI_CR_OFFSET)
 194                          & ~XSPI_CR_MODE_MASK;
 195                 if (spi->mode & SPI_CPHA)
 196                         cr |= XSPI_CR_CPHA;
 197                 if (spi->mode & SPI_CPOL)
 198                         cr |= XSPI_CR_CPOL;
 199                 xspi->write_fn(cr, xspi->regs + XSPI_CR_OFFSET);
 200
 201                 /* We do not check spi->max_speed_hz here as the SPI clock
 202                  * frequency is not software programmable (the IP block design
 203                  * parameter)
 204                  */
 205
 206                 /* Activate the chip select */
 207                 xspi->write_fn(~(0x0001 << spi->chip_select),
 208                         xspi->regs + XSPI_SSR_OFFSET);
 209         }
 210 }
 211
 212 /* spi_bitbang requires custom setup_transfer() to be defined if there is a
 213  * custom txrx_bufs(). We have nothing to setup here as the SPI IP block
 214  * supports 8 or 16 bits per word which cannot be changed in software.
 215  * SPI clock can't be changed in software either.
 216  * Check for correct bits per word. Chip select delay calculations could be
 217  * added here as soon as bitbang_work() can be made aware of the delay value.
 218  */
 219 static int xilinx_spi_setup_transfer(struct spi_device *spi,
 220                 struct spi_transfer *t)
 221 {
 222         struct xilinx_spi *xspi = spi_master_get_devdata(spi->master);
 223         u8 bits_per_word;
 224
 225         bits_per_word = (t && t->bits_per_word)
 226                          ? t->bits_per_word : spi->bits_per_word;
 227         if (bits_per_word != xspi->bits_per_word) {
 228                 dev_err(&spi->dev, "%s, unsupported bits_per_word=%d\n",
 229                         __func__, bits_per_word);
 230                 return -EINVAL;
 231         }
 232
 233         return 0;
 234 }
 235
 236 static int xilinx_spi_setup(struct spi_device *spi)
 237 {
 238         /* always return 0, we can not check the number of bits.
 239          * There are cases when SPI setup is called before any driver is
 240          * there, in that case the SPI core defaults to 8 bits, which we
 241          * do not support in some cases. But if we return an error, the
 242          * SPI device would not be registered and no driver can get hold of it
 243          * When the driver is there, it will call SPI setup again with the
 244          * correct number of bits per transfer.
 245          * If a driver setups with the wrong bit number, it will fail when
 246          * it tries to do a transfer
 247          */
 248         return 0;
 249 }
 250
 251 static void xilinx_spi_fill_tx_fifo(struct xilinx_spi *xspi)
 252 {
 253         u8 sr;
 254
 255         /* Fill the Tx FIFO with as many bytes as possible */
 256         sr = xspi->read_fn(xspi->regs + XSPI_SR_OFFSET);
 257         while ((sr & XSPI_SR_TX_FULL_MASK) == 0 && xspi->remaining_bytes > 0) {
 258                 if (xspi->tx_ptr)
 259                         xspi->tx_fn(xspi);
 260                 else
 261                         xspi->write_fn(0, xspi->regs + XSPI_TXD_OFFSET);
 262                 xspi->remaining_bytes -= xspi->bits_per_word / 8;
 263                 sr = xspi->read_fn(xspi->regs + XSPI_SR_OFFSET);
 264         }
 265 }
 266
 267 static int xilinx_spi_txrx_bufs(struct spi_device *spi, struct spi_transfer *t)
 268 {
 269         struct xilinx_spi *xspi = spi_master_get_devdata(spi->master);
 270         u32 ipif_ier;
 271
 272         /* We get here with transmitter inhibited */
 273
 274         xspi->tx_ptr = t->tx_buf;
 275         xspi->rx_ptr = t->rx_buf;
 276         xspi->remaining_bytes = t->len;
 277         INIT_COMPLETION(xspi->done);
 278
 279
 280         /* Enable the transmit empty interrupt, which we use to determine
 281          * progress on the transmission.
 282          */
 283         ipif_ier = xspi->read_fn(xspi->regs + XIPIF_V123B_IIER_OFFSET);
 284         xspi->write_fn(ipif_ier | XSPI_INTR_TX_EMPTY,
 285                 xspi->regs + XIPIF_V123B_IIER_OFFSET);
 286
 287         for (;;) {
 288                 u16 cr;
 289                 u8 sr;
 290
 291                 xilinx_spi_fill_tx_fifo(xspi);
 292
 293                 /* Start the transfer by not inhibiting the transmitter any
 294                  * longer
 295                  */
 296                 cr = xspi->read_fn(xspi->regs + XSPI_CR_OFFSET) &
 297                                                         ~XSPI_CR_TRANS_INHIBIT;
 298                 xspi->write_fn(cr, xspi->regs + XSPI_CR_OFFSET);
 299
 300                 wait_for_completion(&xspi->done);
 301
 302                 /* A transmit has just completed. Process received data and
 303                  * check for more data to transmit. Always inhibit the
 304                  * transmitter while the Isr refills the transmit register/FIFO,
 305                  * or make sure it is stopped if we're done.
 306                  */
 307                 cr = xspi->read_fn(xspi->regs + XSPI_CR_OFFSET);
 308                 xspi->write_fn(cr | XSPI_CR_TRANS_INHIBIT,
 309                                xspi->regs + XSPI_CR_OFFSET);
 310
 311                 /* Read out all the data from the Rx FIFO */
 312                 sr = xspi->read_fn(xspi->regs + XSPI_SR_OFFSET);
 313                 while ((sr & XSPI_SR_RX_EMPTY_MASK) == 0) {
 314                         xspi->rx_fn(xspi);
 315                         sr = xspi->read_fn(xspi->regs + XSPI_SR_OFFSET);
 316                 }
 317
 318                 /* See if there is more data to send */
 319                 if (xspi->remaining_bytes <= 0)
 320                         break;
 321         }
 322
 323         /* Disable the transmit empty interrupt */
 324         xspi->write_fn(ipif_ier, xspi->regs + XIPIF_V123B_IIER_OFFSET);
 325
 326         return t->len - xspi->remaining_bytes;
 327 }
 328
 329
 330 /* This driver supports single master mode only. Hence Tx FIFO Empty
 331  * is the only interrupt we care about.
 332  * Receive FIFO Overrun, Transmit FIFO Underrun, Mode Fault, and Slave Mode
 333  * Fault are not to happen.
 334  */
 335 static irqreturn_t xilinx_spi_irq(int irq, void *dev_id)
 336 {
 337         struct xilinx_spi *xspi = dev_id;
 338         u32 ipif_isr;
 339
 340         /* Get the IPIF interrupts, and clear them immediately */
 341         ipif_isr = xspi->read_fn(xspi->regs + XIPIF_V123B_IISR_OFFSET);
 342         xspi->write_fn(ipif_isr, xspi->regs + XIPIF_V123B_IISR_OFFSET);
 343
 344         if (ipif_isr & XSPI_INTR_TX_EMPTY) {    /* Transmission completed */
 345                 complete(&xspi->done);
 346         }
 347
 348         return IRQ_HANDLED;
 349 }
 350
 351 static const struct of_device_id xilinx_spi_of_match[] = {
 352         { .compatible = "xlnx,xps-spi-2.00.a", },
 353         { .compatible = "xlnx,xps-spi-2.00.b", },
 354         {}
 355 };
 356 MODULE_DEVICE_TABLE(of, xilinx_spi_of_match);
 357
 358 struct spi_master *xilinx_spi_init(struct device *dev, struct resource *mem,
 359         u32 irq, s16 bus_num, int num_cs, int bits_per_word)
 360 {
 361         struct spi_master *master;
 362         struct xilinx_spi *xspi;
 363         int ret;
 364         u32 tmp;
 365
 366         master = spi_alloc_master(dev, sizeof(struct xilinx_spi));
 367         if (!master)
 368                 return NULL;
 369
 370         /* the spi->mode bits understood by this driver: */
 371         master->mode_bits = SPI_CPOL | SPI_CPHA;
 372
 373         xspi = spi_master_get_devdata(master);
 374         xspi->bitbang.master = spi_master_get(master);
 375         xspi->bitbang.chipselect = xilinx_spi_chipselect;
 376         xspi->bitbang.setup_transfer = xilinx_spi_setup_transfer;
 377         xspi->bitbang.txrx_bufs = xilinx_spi_txrx_bufs;
 378         xspi->bitbang.master->setup = xilinx_spi_setup;
 379         init_completion(&xspi->done);
 380
 381         if (!request_mem_region(mem->start, resource_size(mem),
 382                 XILINX_SPI_NAME))
 383                 goto put_master;
 384
 385         xspi->regs = ioremap(mem->start, resource_size(mem));
 386         if (xspi->regs == NULL) {
 387                 dev_warn(dev, "ioremap failure\n");
 388                 goto map_failed;
 389         }
 390
 391         master->bus_num = bus_num;
 392         master->num_chipselect = num_cs;
 393         master->dev.of_node = dev->of_node;
 394
 395         xspi->mem = *mem;
 396         xspi->irq = irq;
 397
 398         /*
 399          * Detect endianess on the IP via loop bit in CR. Detection
 400          * must be done before reset is sent because incorrect reset
 401          * value generates error interrupt.
 402          * Setup little endian helper functions first and try to use them
 403          * and check if bit was correctly setup or not.
 404          */
 405         xspi->read_fn = xspi_read32;
 406         xspi->write_fn = xspi_write32;
 407
 408         xspi->write_fn(XSPI_CR_LOOP, xspi->regs + XSPI_CR_OFFSET);
 409         tmp = xspi->read_fn(xspi->regs + XSPI_CR_OFFSET);
 410         tmp &= XSPI_CR_LOOP;
 411         if (tmp != XSPI_CR_LOOP) {
 412                 xspi->read_fn = xspi_read32_be;
 413                 xspi->write_fn = xspi_write32_be;
 414         }
 415
 416         xspi->bits_per_word = bits_per_word;
 417         if (xspi->bits_per_word == 8) {
 418                 xspi->tx_fn = xspi_tx8;
 419                 xspi->rx_fn = xspi_rx8;
 420         } else if (xspi->bits_per_word == 16) {
 421                 xspi->tx_fn = xspi_tx16;
 422                 xspi->rx_fn = xspi_rx16;
 423         } else if (xspi->bits_per_word == 32) {
 424                 xspi->tx_fn = xspi_tx32;
 425                 xspi->rx_fn = xspi_rx32;
 426         } else
 427                 goto unmap_io;
 428
 429
 430         /* SPI controller initializations */
 431         xspi_init_hw(xspi);
 432
 433         /* Register for SPI Interrupt */
 434         ret = request_irq(xspi->irq, xilinx_spi_irq, 0, XILINX_SPI_NAME, xspi);
 435         if (ret)
 436                 goto unmap_io;
 437
 438         ret = spi_bitbang_start(&xspi->bitbang);
 439         if (ret) {
 440                 dev_err(dev, "spi_bitbang_start FAILED\n");
 441                 goto free_irq;
 442         }
 443
 444         dev_info(dev, "at 0x%08llX mapped to 0x%p, irq=%d\n",
 445                 (unsigned long long)mem->start, xspi->regs, xspi->irq);
 446         return master;
 447
 448 free_irq:
 449         free_irq(xspi->irq, xspi);
 450 unmap_io:
 451         iounmap(xspi->regs);
 452 map_failed:
 453         release_mem_region(mem->start, resource_size(mem));
 454 put_master:
 455         spi_master_put(master);
 456         return NULL;
 457 }
 458 EXPORT_SYMBOL(xilinx_spi_init);
 459
 460 void xilinx_spi_deinit(struct spi_master *master)
 461 {
 462         struct xilinx_spi *xspi;
 463
 464         xspi = spi_master_get_devdata(master);
 465
 466         spi_bitbang_stop(&xspi->bitbang);
 467         free_irq(xspi->irq, xspi);
 468         iounmap(xspi->regs);
 469
 470         release_mem_region(xspi->mem.start, resource_size(&xspi->mem));
 471         spi_master_put(xspi->bitbang.master);
 472 }
 473 EXPORT_SYMBOL(xilinx_spi_deinit);
 474
 475 static int xilinx_spi_probe(struct platform_device *dev)
 476 {
 477         struct xspi_platform_data *pdata;
 478         struct resource *r;
 479         int irq, num_cs = 0, bits_per_word = 8;
 480         struct spi_master *master;
 481         u8 i;
 482
 483         pdata = dev->dev.platform_data;
 484         if (pdata) {
 485                 num_cs = pdata->num_chipselect;
 486                 bits_per_word = pdata->bits_per_word;
 487         }
 488
 489 #ifdef CONFIG_OF
 490         if (dev->dev.of_node) {
 491                 const __be32 *prop;
 492                 int len;
 493
 494                 /* number of slave select bits is required */
 495                 prop = of_get_property(dev->dev.of_node, "xlnx,num-ss-bits",
 496                                        &len);
 497                 if (prop && len >= sizeof(*prop))
 498                         num_cs = __be32_to_cpup(prop);
 499         }
 500 #endif
 501
 502         if (!num_cs) {
 503                 dev_err(&dev->dev, "Missing slave select configuration data\n");
 504                 return -EINVAL;
 505         }
 506
 507
 508         r = platform_get_resource(dev, IORESOURCE_MEM, 0);
 509         if (!r)
 510                 return -ENODEV;
 511
 512         irq = platform_get_irq(dev, 0);
 513         if (irq < 0)
 514                 return -ENXIO;
 515
 516         master = xilinx_spi_init(&dev->dev, r, irq, dev->id, num_cs,
 517                                  bits_per_word);
 518         if (!master)
 519                 return -ENODEV;
 520
 521         if (pdata) {
 522                 for (i = 0; i < pdata->num_devices; i++)
 523                         spi_new_device(master, pdata->devices + i);
 524         }
 525
 526         platform_set_drvdata(dev, master);
 527         return 0;
 528 }
 529
 530 static int xilinx_spi_remove(struct platform_device *dev)
 531 {
 532         xilinx_spi_deinit(platform_get_drvdata(dev));
 533
 534         return 0;
 535 }
 536
 537 /* work with hotplug and coldplug */
 538 MODULE_ALIAS("platform:" XILINX_SPI_NAME);
 539
 540 static struct platform_driver xilinx_spi_driver = {
 541         .probe = xilinx_spi_probe,
 542         .remove = xilinx_spi_remove,
 543         .driver = {
 544                 .name = XILINX_SPI_NAME,
 545                 .owner = THIS_MODULE,
 546                 .of_match_table = xilinx_spi_of_match,
 547         },
 548 };
 549 module_platform_driver(xilinx_spi_driver);
 550
 551 MODULE_AUTHOR("MontaVista Software, Inc. <source@mvista.com>");
 552 MODULE_DESCRIPTION("Xilinx SPI driver");
 553 MODULE_LICENSE("GPL");