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