LXR linux/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/interrupt.h>
  18#include <linux/of.h>
  19#include <linux/platform_device.h>
  20#include <linux/spi/spi.h>
  21#include <linux/spi/spi_bitbang.h>
  22#include <linux/spi/xilinx_spi.h>
  23#include <linux/io.h>
  24
  25#define XILINX_SPI_MAX_CS       32
  26
  27#define XILINX_SPI_NAME "xilinx_spi"
  28
  29/* Register definitions as per "OPB Serial Peripheral Interface (SPI) (v1.00e)
  30 * Product Specification", DS464
  31 */
  32#define XSPI_CR_OFFSET          0x60    /* Control Register */
  33
  34#define XSPI_CR_LOOP            0x01
  35#define XSPI_CR_ENABLE          0x02
  36#define XSPI_CR_MASTER_MODE     0x04
  37#define XSPI_CR_CPOL            0x08
  38#define XSPI_CR_CPHA            0x10
  39#define XSPI_CR_MODE_MASK       (XSPI_CR_CPHA | XSPI_CR_CPOL | \
  40                                 XSPI_CR_LSB_FIRST | XSPI_CR_LOOP)
  41#define XSPI_CR_TXFIFO_RESET    0x20
  42#define XSPI_CR_RXFIFO_RESET    0x40
  43#define XSPI_CR_MANUAL_SSELECT  0x80
  44#define XSPI_CR_TRANS_INHIBIT   0x100
  45#define XSPI_CR_LSB_FIRST       0x200
  46
  47#define XSPI_SR_OFFSET          0x64    /* Status Register */
  48
  49#define XSPI_SR_RX_EMPTY_MASK   0x01    /* Receive FIFO is empty */
  50#define XSPI_SR_RX_FULL_MASK    0x02    /* Receive FIFO is full */
  51#define XSPI_SR_TX_EMPTY_MASK   0x04    /* Transmit FIFO is empty */
  52#define XSPI_SR_TX_FULL_MASK    0x08    /* Transmit FIFO is full */
  53#define XSPI_SR_MODE_FAULT_MASK 0x10    /* Mode fault error */
  54
  55#define XSPI_TXD_OFFSET         0x68    /* Data Transmit Register */
  56#define XSPI_RXD_OFFSET         0x6c    /* Data Receive Register */
  57
  58#define XSPI_SSR_OFFSET         0x70    /* 32-bit Slave Select Register */
  59
  60/* Register definitions as per "OPB IPIF (v3.01c) Product Specification", DS414
  61 * IPIF registers are 32 bit
  62 */
  63#define XIPIF_V123B_DGIER_OFFSET        0x1c    /* IPIF global int enable reg */
  64#define XIPIF_V123B_GINTR_ENABLE        0x80000000
  65
  66#define XIPIF_V123B_IISR_OFFSET         0x20    /* IPIF interrupt status reg */
  67#define XIPIF_V123B_IIER_OFFSET         0x28    /* IPIF interrupt enable reg */
  68
  69#define XSPI_INTR_MODE_FAULT            0x01    /* Mode fault error */
  70#define XSPI_INTR_SLAVE_MODE_FAULT      0x02    /* Selected as slave while
  71                                                 * disabled */
  72#define XSPI_INTR_TX_EMPTY              0x04    /* TxFIFO is empty */
  73#define XSPI_INTR_TX_UNDERRUN           0x08    /* TxFIFO was underrun */
  74#define XSPI_INTR_RX_FULL               0x10    /* RxFIFO is full */
  75#define XSPI_INTR_RX_OVERRUN            0x20    /* RxFIFO was overrun */
  76#define XSPI_INTR_TX_HALF_EMPTY         0x40    /* TxFIFO is half empty */
  77
  78#define XIPIF_V123B_RESETR_OFFSET       0x40    /* IPIF reset register */
  79#define XIPIF_V123B_RESET_MASK          0x0a    /* the value to write */
  80
  81struct xilinx_spi {
  82        /* bitbang has to be first */
  83        struct spi_bitbang bitbang;
  84        struct completion done;
  85        void __iomem    *regs;  /* virt. address of the control registers */
  86
  87        int             irq;
  88
  89        u8 *rx_ptr;             /* pointer in the Tx buffer */
  90        const u8 *tx_ptr;       /* pointer in the Rx buffer */
  91        u8 bytes_per_word;
  92        int buffer_size;        /* buffer size in words */
  93        u32 cs_inactive;        /* Level of the CS pins when inactive*/
  94        unsigned int (*read_fn)(void __iomem *);
  95        void (*write_fn)(u32, void __iomem *);
  96};
  97
  98static void xspi_write32(u32 val, void __iomem *addr)
  99{
 100        iowrite32(val, addr);
 101}
 102
 103static unsigned int xspi_read32(void __iomem *addr)
 104{
 105        return ioread32(addr);
 106}
 107
 108static void xspi_write32_be(u32 val, void __iomem *addr)
 109{
 110        iowrite32be(val, addr);
 111}
 112
 113static unsigned int xspi_read32_be(void __iomem *addr)
 114{
 115        return ioread32be(addr);
 116}
 117
 118static void xilinx_spi_tx(struct xilinx_spi *xspi)
 119{
 120        u32 data = 0;
 121
 122        if (!xspi->tx_ptr) {
 123                xspi->write_fn(0, xspi->regs + XSPI_TXD_OFFSET);
 124                return;
 125        }
 126
 127        switch (xspi->bytes_per_word) {
 128        case 1:
 129                data = *(u8 *)(xspi->tx_ptr);
 130                break;
 131        case 2:
 132                data = *(u16 *)(xspi->tx_ptr);
 133                break;
 134        case 4:
 135                data = *(u32 *)(xspi->tx_ptr);
 136                break;
 137        }
 138
 139        xspi->write_fn(data, xspi->regs + XSPI_TXD_OFFSET);
 140        xspi->tx_ptr += xspi->bytes_per_word;
 141}
 142
 143static void xilinx_spi_rx(struct xilinx_spi *xspi)
 144{
 145        u32 data = xspi->read_fn(xspi->regs + XSPI_RXD_OFFSET);
 146
 147        if (!xspi->rx_ptr)
 148                return;
 149
 150        switch (xspi->bytes_per_word) {
 151        case 1:
 152                *(u8 *)(xspi->rx_ptr) = data;
 153                break;
 154        case 2:
 155                *(u16 *)(xspi->rx_ptr) = data;
 156                break;
 157        case 4:
 158                *(u32 *)(xspi->rx_ptr) = data;
 159                break;
 160        }
 161
 162        xspi->rx_ptr += xspi->bytes_per_word;
 163}
 164
 165static void xspi_init_hw(struct xilinx_spi *xspi)
 166{
 167        void __iomem *regs_base = xspi->regs;
 168
 169        /* Reset the SPI device */
 170        xspi->write_fn(XIPIF_V123B_RESET_MASK,
 171                regs_base + XIPIF_V123B_RESETR_OFFSET);
 172        /* Enable the transmit empty interrupt, which we use to determine
 173         * progress on the transmission.
 174         */
 175        xspi->write_fn(XSPI_INTR_TX_EMPTY,
 176                        regs_base + XIPIF_V123B_IIER_OFFSET);
 177        /* Disable the global IPIF interrupt */
 178        xspi->write_fn(0, regs_base + XIPIF_V123B_DGIER_OFFSET);
 179        /* Deselect the slave on the SPI bus */
 180        xspi->write_fn(0xffff, regs_base + XSPI_SSR_OFFSET);
 181        /* Disable the transmitter, enable Manual Slave Select Assertion,
 182         * put SPI controller into master mode, and enable it */
 183        xspi->write_fn(XSPI_CR_MANUAL_SSELECT | XSPI_CR_MASTER_MODE |
 184                XSPI_CR_ENABLE | XSPI_CR_TXFIFO_RESET | XSPI_CR_RXFIFO_RESET,
 185                regs_base + XSPI_CR_OFFSET);
 186}
 187
 188static void xilinx_spi_chipselect(struct spi_device *spi, int is_on)
 189{
 190        struct xilinx_spi *xspi = spi_master_get_devdata(spi->master);
 191        u16 cr;
 192        u32 cs;
 193
 194        if (is_on == BITBANG_CS_INACTIVE) {
 195                /* Deselect the slave on the SPI bus */
 196                xspi->write_fn(xspi->cs_inactive, xspi->regs + XSPI_SSR_OFFSET);
 197                return;
 198        }
 199
 200        /* Set the SPI clock phase and polarity */
 201        cr = xspi->read_fn(xspi->regs + XSPI_CR_OFFSET) & ~XSPI_CR_MODE_MASK;
 202        if (spi->mode & SPI_CPHA)
 203                cr |= XSPI_CR_CPHA;
 204        if (spi->mode & SPI_CPOL)
 205                cr |= XSPI_CR_CPOL;
 206        if (spi->mode & SPI_LSB_FIRST)
 207                cr |= XSPI_CR_LSB_FIRST;
 208        if (spi->mode & SPI_LOOP)
 209                cr |= XSPI_CR_LOOP;
 210        xspi->write_fn(cr, xspi->regs + XSPI_CR_OFFSET);
 211
 212        /* We do not check spi->max_speed_hz here as the SPI clock
 213         * frequency is not software programmable (the IP block design
 214         * parameter)
 215         */
 216
 217        cs = xspi->cs_inactive;
 218        cs ^= BIT(spi->chip_select);
 219
 220        /* Activate the chip select */
 221        xspi->write_fn(cs, xspi->regs + XSPI_SSR_OFFSET);
 222}
 223
 224/* spi_bitbang requires custom setup_transfer() to be defined if there is a
 225 * custom txrx_bufs().
 226 */
 227static int xilinx_spi_setup_transfer(struct spi_device *spi,
 228                struct spi_transfer *t)
 229{
 230        struct xilinx_spi *xspi = spi_master_get_devdata(spi->master);
 231
 232        if (spi->mode & SPI_CS_HIGH)
 233                xspi->cs_inactive &= ~BIT(spi->chip_select);
 234        else
 235                xspi->cs_inactive |= BIT(spi->chip_select);
 236
 237        return 0;
 238}
 239
 240static int xilinx_spi_txrx_bufs(struct spi_device *spi, struct spi_transfer *t)
 241{
 242        struct xilinx_spi *xspi = spi_master_get_devdata(spi->master);
 243        int remaining_words;    /* the number of words left to transfer */
 244        bool use_irq = false;
 245        u16 cr = 0;
 246
 247        /* We get here with transmitter inhibited */
 248
 249        xspi->tx_ptr = t->tx_buf;
 250        xspi->rx_ptr = t->rx_buf;
 251        remaining_words = t->len / xspi->bytes_per_word;
 252
 253        if (xspi->irq >= 0 &&  remaining_words > xspi->buffer_size) {
 254                u32 isr;
 255                use_irq = true;
 256                /* Inhibit irq to avoid spurious irqs on tx_empty*/
 257                cr = xspi->read_fn(xspi->regs + XSPI_CR_OFFSET);
 258                xspi->write_fn(cr | XSPI_CR_TRANS_INHIBIT,
 259                               xspi->regs + XSPI_CR_OFFSET);
 260                /* ACK old irqs (if any) */
 261                isr = xspi->read_fn(xspi->regs + XIPIF_V123B_IISR_OFFSET);
 262                if (isr)
 263                        xspi->write_fn(isr,
 264                                       xspi->regs + XIPIF_V123B_IISR_OFFSET);
 265                /* Enable the global IPIF interrupt */
 266                xspi->write_fn(XIPIF_V123B_GINTR_ENABLE,
 267                                xspi->regs + XIPIF_V123B_DGIER_OFFSET);
 268                reinit_completion(&xspi->done);
 269        }
 270
 271        while (remaining_words) {
 272                int n_words, tx_words, rx_words;
 273                u32 sr;
 274                int stalled;
 275
 276                n_words = min(remaining_words, xspi->buffer_size);
 277
 278                tx_words = n_words;
 279                while (tx_words--)
 280                        xilinx_spi_tx(xspi);
 281
 282                /* Start the transfer by not inhibiting the transmitter any
 283                 * longer
 284                 */
 285
 286                if (use_irq) {
 287                        xspi->write_fn(cr, xspi->regs + XSPI_CR_OFFSET);
 288                        wait_for_completion(&xspi->done);
 289                        /* A transmit has just completed. Process received data
 290                         * and check for more data to transmit. Always inhibit
 291                         * the transmitter while the Isr refills the transmit
 292                         * register/FIFO, or make sure it is stopped if we're
 293                         * done.
 294                         */
 295                        xspi->write_fn(cr | XSPI_CR_TRANS_INHIBIT,
 296                                       xspi->regs + XSPI_CR_OFFSET);
 297                        sr = XSPI_SR_TX_EMPTY_MASK;
 298                } else
 299                        sr = xspi->read_fn(xspi->regs + XSPI_SR_OFFSET);
 300
 301                /* Read out all the data from the Rx FIFO */
 302                rx_words = n_words;
 303                stalled = 10;
 304                while (rx_words) {
 305                        if (rx_words == n_words && !(stalled--) &&
 306                            !(sr & XSPI_SR_TX_EMPTY_MASK) &&
 307                            (sr & XSPI_SR_RX_EMPTY_MASK)) {
 308                                dev_err(&spi->dev,
 309                                        "Detected stall. Check C_SPI_MODE and C_SPI_MEMORY\n");
 310                                xspi_init_hw(xspi);
 311                                return -EIO;
 312                        }
 313
 314                        if ((sr & XSPI_SR_TX_EMPTY_MASK) && (rx_words > 1)) {
 315                                xilinx_spi_rx(xspi);
 316                                rx_words--;
 317                                continue;
 318                        }
 319
 320                        sr = xspi->read_fn(xspi->regs + XSPI_SR_OFFSET);
 321                        if (!(sr & XSPI_SR_RX_EMPTY_MASK)) {
 322                                xilinx_spi_rx(xspi);
 323                                rx_words--;
 324                        }
 325                }
 326
 327                remaining_words -= n_words;
 328        }
 329
 330        if (use_irq) {
 331                xspi->write_fn(0, xspi->regs + XIPIF_V123B_DGIER_OFFSET);
 332                xspi->write_fn(cr, xspi->regs + XSPI_CR_OFFSET);
 333        }
 334
 335        return t->len;
 336}
 337
 338
 339/* This driver supports single master mode only. Hence Tx FIFO Empty
 340 * is the only interrupt we care about.
 341 * Receive FIFO Overrun, Transmit FIFO Underrun, Mode Fault, and Slave Mode
 342 * Fault are not to happen.
 343 */
 344static irqreturn_t xilinx_spi_irq(int irq, void *dev_id)
 345{
 346        struct xilinx_spi *xspi = dev_id;
 347        u32 ipif_isr;
 348
 349        /* Get the IPIF interrupts, and clear them immediately */
 350        ipif_isr = xspi->read_fn(xspi->regs + XIPIF_V123B_IISR_OFFSET);
 351        xspi->write_fn(ipif_isr, xspi->regs + XIPIF_V123B_IISR_OFFSET);
 352
 353        if (ipif_isr & XSPI_INTR_TX_EMPTY) {    /* Transmission completed */
 354                complete(&xspi->done);
 355                return IRQ_HANDLED;
 356        }
 357
 358        return IRQ_NONE;
 359}
 360
 361static int xilinx_spi_find_buffer_size(struct xilinx_spi *xspi)
 362{
 363        u8 sr;
 364        int n_words = 0;
 365
 366        /*
 367         * Before the buffer_size detection we reset the core
 368         * to make sure we start with a clean state.
 369         */
 370        xspi->write_fn(XIPIF_V123B_RESET_MASK,
 371                xspi->regs + XIPIF_V123B_RESETR_OFFSET);
 372
 373        /* Fill the Tx FIFO with as many words as possible */
 374        do {
 375                xspi->write_fn(0, xspi->regs + XSPI_TXD_OFFSET);
 376                sr = xspi->read_fn(xspi->regs + XSPI_SR_OFFSET);
 377                n_words++;
 378        } while (!(sr & XSPI_SR_TX_FULL_MASK));
 379
 380        return n_words;
 381}
 382
 383static const struct of_device_id xilinx_spi_of_match[] = {
 384        { .compatible = "xlnx,axi-quad-spi-1.00.a", },
 385        { .compatible = "xlnx,xps-spi-2.00.a", },
 386        { .compatible = "xlnx,xps-spi-2.00.b", },
 387        {}
 388};
 389MODULE_DEVICE_TABLE(of, xilinx_spi_of_match);
 390
 391static int xilinx_spi_probe(struct platform_device *pdev)
 392{
 393        struct xilinx_spi *xspi;
 394        struct xspi_platform_data *pdata;
 395        struct resource *res;
 396        int ret, num_cs = 0, bits_per_word = 8;
 397        struct spi_master *master;
 398        u32 tmp;
 399        u8 i;
 400
 401        pdata = dev_get_platdata(&pdev->dev);
 402        if (pdata) {
 403                num_cs = pdata->num_chipselect;
 404                bits_per_word = pdata->bits_per_word;
 405        } else {
 406                of_property_read_u32(pdev->dev.of_node, "xlnx,num-ss-bits",
 407                                          &num_cs);
 408        }
 409
 410        if (!num_cs) {
 411                dev_err(&pdev->dev,
 412                        "Missing slave select configuration data\n");
 413                return -EINVAL;
 414        }
 415
 416        if (num_cs > XILINX_SPI_MAX_CS) {
 417                dev_err(&pdev->dev, "Invalid number of spi slaves\n");
 418                return -EINVAL;
 419        }
 420
 421        master = spi_alloc_master(&pdev->dev, sizeof(struct xilinx_spi));
 422        if (!master)
 423                return -ENODEV;
 424
 425        /* the spi->mode bits understood by this driver: */
 426        master->mode_bits = SPI_CPOL | SPI_CPHA | SPI_LSB_FIRST | SPI_LOOP |
 427                            SPI_CS_HIGH;
 428
 429        xspi = spi_master_get_devdata(master);
 430        xspi->cs_inactive = 0xffffffff;
 431        xspi->bitbang.master = master;
 432        xspi->bitbang.chipselect = xilinx_spi_chipselect;
 433        xspi->bitbang.setup_transfer = xilinx_spi_setup_transfer;
 434        xspi->bitbang.txrx_bufs = xilinx_spi_txrx_bufs;
 435        init_completion(&xspi->done);
 436
 437        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 438        xspi->regs = devm_ioremap_resource(&pdev->dev, res);
 439        if (IS_ERR(xspi->regs)) {
 440                ret = PTR_ERR(xspi->regs);
 441                goto put_master;
 442        }
 443
 444        master->bus_num = pdev->id;
 445        master->num_chipselect = num_cs;
 446        master->dev.of_node = pdev->dev.of_node;
 447
 448        /*
 449         * Detect endianess on the IP via loop bit in CR. Detection
 450         * must be done before reset is sent because incorrect reset
 451         * value generates error interrupt.
 452         * Setup little endian helper functions first and try to use them
 453         * and check if bit was correctly setup or not.
 454         */
 455        xspi->read_fn = xspi_read32;
 456        xspi->write_fn = xspi_write32;
 457
 458        xspi->write_fn(XSPI_CR_LOOP, xspi->regs + XSPI_CR_OFFSET);
 459        tmp = xspi->read_fn(xspi->regs + XSPI_CR_OFFSET);
 460        tmp &= XSPI_CR_LOOP;
 461        if (tmp != XSPI_CR_LOOP) {
 462                xspi->read_fn = xspi_read32_be;
 463                xspi->write_fn = xspi_write32_be;
 464        }
 465
 466        master->bits_per_word_mask = SPI_BPW_MASK(bits_per_word);
 467        xspi->bytes_per_word = bits_per_word / 8;
 468        xspi->buffer_size = xilinx_spi_find_buffer_size(xspi);
 469
 470        xspi->irq = platform_get_irq(pdev, 0);
 471        if (xspi->irq < 0 && xspi->irq != -ENXIO) {
 472                ret = xspi->irq;
 473                goto put_master;
 474        } else if (xspi->irq >= 0) {
 475                /* Register for SPI Interrupt */
 476                ret = devm_request_irq(&pdev->dev, xspi->irq, xilinx_spi_irq, 0,
 477                                dev_name(&pdev->dev), xspi);
 478                if (ret)
 479                        goto put_master;
 480        }
 481
 482        /* SPI controller initializations */
 483        xspi_init_hw(xspi);
 484
 485        ret = spi_bitbang_start(&xspi->bitbang);
 486        if (ret) {
 487                dev_err(&pdev->dev, "spi_bitbang_start FAILED\n");
 488                goto put_master;
 489        }
 490
 491        dev_info(&pdev->dev, "at 0x%08llX mapped to 0x%p, irq=%d\n",
 492                (unsigned long long)res->start, xspi->regs, xspi->irq);
 493
 494        if (pdata) {
 495                for (i = 0; i < pdata->num_devices; i++)
 496                        spi_new_device(master, pdata->devices + i);
 497        }
 498
 499        platform_set_drvdata(pdev, master);
 500        return 0;
 501
 502put_master:
 503        spi_master_put(master);
 504
 505        return ret;
 506}
 507
 508static int xilinx_spi_remove(struct platform_device *pdev)
 509{
 510        struct spi_master *master = platform_get_drvdata(pdev);
 511        struct xilinx_spi *xspi = spi_master_get_devdata(master);
 512        void __iomem *regs_base = xspi->regs;
 513
 514        spi_bitbang_stop(&xspi->bitbang);
 515
 516        /* Disable all the interrupts just in case */
 517        xspi->write_fn(0, regs_base + XIPIF_V123B_IIER_OFFSET);
 518        /* Disable the global IPIF interrupt */
 519        xspi->write_fn(0, regs_base + XIPIF_V123B_DGIER_OFFSET);
 520
 521        spi_master_put(xspi->bitbang.master);
 522
 523        return 0;
 524}
 525
 526/* work with hotplug and coldplug */
 527MODULE_ALIAS("platform:" XILINX_SPI_NAME);
 528
 529static struct platform_driver xilinx_spi_driver = {
 530        .probe = xilinx_spi_probe,
 531        .remove = xilinx_spi_remove,
 532        .driver = {
 533                .name = XILINX_SPI_NAME,
 534                .of_match_table = xilinx_spi_of_match,
 535        },
 536};
 537module_platform_driver(xilinx_spi_driver);
 538
 539MODULE_AUTHOR("MontaVista Software, Inc. <source@mvista.com>");
 540MODULE_DESCRIPTION("Xilinx SPI driver");
 541MODULE_LICENSE("GPL");
 542