drivers/spi/spi-bcm2835.c

   1 /*
   2  * Driver for Broadcom BCM2835 SPI Controllers
   3  *
   4  * Copyright (C) 2012 Chris Boot
   5  * Copyright (C) 2013 Stephen Warren
   6  * Copyright (C) 2015 Martin Sperl
   7  *
   8  * This driver is inspired by:
   9  * spi-ath79.c, Copyright (C) 2009-2011 Gabor Juhos <juhosg@openwrt.org>
  10  * spi-atmel.c, Copyright (C) 2006 Atmel Corporation
  11  *
  12  * This program is free software; you can redistribute it and/or modify
  13  * it under the terms of the GNU General Public License as published by
  14  * the Free Software Foundation; either version 2 of the License, or
  15  * (at your option) any later version.
  16  *
  17  * This program is distributed in the hope that it will be useful,
  18  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  19  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  20  * GNU General Public License for more details.
  21  */
  22
  23 #include <asm/page.h>
  24 #include <linux/clk.h>
  25 #include <linux/completion.h>
  26 #include <linux/delay.h>
  27 #include <linux/dma-mapping.h>
  28 #include <linux/dmaengine.h>
  29 #include <linux/err.h>
  30 #include <linux/interrupt.h>
  31 #include <linux/io.h>
  32 #include <linux/kernel.h>
  33 #include <linux/module.h>
  34 #include <linux/of.h>
  35 #include <linux/of_address.h>
  36 #include <linux/of_device.h>
  37 #include <linux/of_gpio.h>
  38 #include <linux/of_irq.h>
  39 #include <linux/spi/spi.h>
  40
  41 /* SPI register offsets */
  42 #define BCM2835_SPI_CS                  0x00
  43 #define BCM2835_SPI_FIFO                0x04
  44 #define BCM2835_SPI_CLK                 0x08
  45 #define BCM2835_SPI_DLEN                0x0c
  46 #define BCM2835_SPI_LTOH                0x10
  47 #define BCM2835_SPI_DC                  0x14
  48
  49 /* Bitfields in CS */
  50 #define BCM2835_SPI_CS_LEN_LONG         0x02000000
  51 #define BCM2835_SPI_CS_DMA_LEN          0x01000000
  52 #define BCM2835_SPI_CS_CSPOL2           0x00800000
  53 #define BCM2835_SPI_CS_CSPOL1           0x00400000
  54 #define BCM2835_SPI_CS_CSPOL0           0x00200000
  55 #define BCM2835_SPI_CS_RXF              0x00100000
  56 #define BCM2835_SPI_CS_RXR              0x00080000
  57 #define BCM2835_SPI_CS_TXD              0x00040000
  58 #define BCM2835_SPI_CS_RXD              0x00020000
  59 #define BCM2835_SPI_CS_DONE             0x00010000
  60 #define BCM2835_SPI_CS_LEN              0x00002000
  61 #define BCM2835_SPI_CS_REN              0x00001000
  62 #define BCM2835_SPI_CS_ADCS             0x00000800
  63 #define BCM2835_SPI_CS_INTR             0x00000400
  64 #define BCM2835_SPI_CS_INTD             0x00000200
  65 #define BCM2835_SPI_CS_DMAEN            0x00000100
  66 #define BCM2835_SPI_CS_TA               0x00000080
  67 #define BCM2835_SPI_CS_CSPOL            0x00000040
  68 #define BCM2835_SPI_CS_CLEAR_RX         0x00000020
  69 #define BCM2835_SPI_CS_CLEAR_TX         0x00000010
  70 #define BCM2835_SPI_CS_CPOL             0x00000008
  71 #define BCM2835_SPI_CS_CPHA             0x00000004
  72 #define BCM2835_SPI_CS_CS_10            0x00000002
  73 #define BCM2835_SPI_CS_CS_01            0x00000001
  74
  75 #define BCM2835_SPI_POLLING_LIMIT_US    30
  76 #define BCM2835_SPI_POLLING_JIFFIES     2
  77 #define BCM2835_SPI_DMA_MIN_LENGTH      96
  78 #define BCM2835_SPI_MODE_BITS   (SPI_CPOL | SPI_CPHA | SPI_CS_HIGH \
  79                                 | SPI_NO_CS | SPI_3WIRE)
  80
  81 #define DRV_NAME        "spi-bcm2835"
  82
  83 struct bcm2835_spi {
  84         void __iomem *regs;
  85         struct clk *clk;
  86         int irq;
  87         const u8 *tx_buf;
  88         u8 *rx_buf;
  89         int tx_len;
  90         int rx_len;
  91         bool dma_pending;
  92 };
  93
  94 static inline u32 bcm2835_rd(struct bcm2835_spi *bs, unsigned reg)
  95 {
  96         return readl(bs->regs + reg);
  97 }
  98
  99 static inline void bcm2835_wr(struct bcm2835_spi *bs, unsigned reg, u32 val)
 100 {
 101         writel(val, bs->regs + reg);
 102 }
 103
 104 static inline void bcm2835_rd_fifo(struct bcm2835_spi *bs)
 105 {
 106         u8 byte;
 107
 108         while ((bs->rx_len) &&
 109                (bcm2835_rd(bs, BCM2835_SPI_CS) & BCM2835_SPI_CS_RXD)) {
 110                 byte = bcm2835_rd(bs, BCM2835_SPI_FIFO);
 111                 if (bs->rx_buf)
 112                         *bs->rx_buf++ = byte;
 113                 bs->rx_len--;
 114         }
 115 }
 116
 117 static inline void bcm2835_wr_fifo(struct bcm2835_spi *bs)
 118 {
 119         u8 byte;
 120
 121         while ((bs->tx_len) &&
 122                (bcm2835_rd(bs, BCM2835_SPI_CS) & BCM2835_SPI_CS_TXD)) {
 123                 byte = bs->tx_buf ? *bs->tx_buf++ : 0;
 124                 bcm2835_wr(bs, BCM2835_SPI_FIFO, byte);
 125                 bs->tx_len--;
 126         }
 127 }
 128
 129 static void bcm2835_spi_reset_hw(struct spi_master *master)
 130 {
 131         struct bcm2835_spi *bs = spi_master_get_devdata(master);
 132         u32 cs = bcm2835_rd(bs, BCM2835_SPI_CS);
 133
 134         /* Disable SPI interrupts and transfer */
 135         cs &= ~(BCM2835_SPI_CS_INTR |
 136                 BCM2835_SPI_CS_INTD |
 137                 BCM2835_SPI_CS_DMAEN |
 138                 BCM2835_SPI_CS_TA);
 139         /* and reset RX/TX FIFOS */
 140         cs |= BCM2835_SPI_CS_CLEAR_RX | BCM2835_SPI_CS_CLEAR_TX;
 141
 142         /* and reset the SPI_HW */
 143         bcm2835_wr(bs, BCM2835_SPI_CS, cs);
 144         /* as well as DLEN */
 145         bcm2835_wr(bs, BCM2835_SPI_DLEN, 0);
 146 }
 147
 148 static irqreturn_t bcm2835_spi_interrupt(int irq, void *dev_id)
 149 {
 150         struct spi_master *master = dev_id;
 151         struct bcm2835_spi *bs = spi_master_get_devdata(master);
 152
 153         /* Read as many bytes as possible from FIFO */
 154         bcm2835_rd_fifo(bs);
 155         /* Write as many bytes as possible to FIFO */
 156         bcm2835_wr_fifo(bs);
 157
 158         /* based on flags decide if we can finish the transfer */
 159         if (bcm2835_rd(bs, BCM2835_SPI_CS) & BCM2835_SPI_CS_DONE) {
 160                 /* Transfer complete - reset SPI HW */
 161                 bcm2835_spi_reset_hw(master);
 162                 /* wake up the framework */
 163                 complete(&master->xfer_completion);
 164         }
 165
 166         return IRQ_HANDLED;
 167 }
 168
 169 static int bcm2835_spi_transfer_one_irq(struct spi_master *master,
 170                                         struct spi_device *spi,
 171                                         struct spi_transfer *tfr,
 172                                         u32 cs)
 173 {
 174         struct bcm2835_spi *bs = spi_master_get_devdata(master);
 175
 176         /* fill in fifo if we have gpio-cs
 177          * note that there have been rare events where the native-CS
 178          * flapped for <1us which may change the behaviour
 179          * with gpio-cs this does not happen, so it is implemented
 180          * only for this case
 181          */
 182         if (gpio_is_valid(spi->cs_gpio)) {
 183                 /* enable HW block, but without interrupts enabled
 184                  * this would triggern an immediate interrupt
 185                  */
 186                 bcm2835_wr(bs, BCM2835_SPI_CS,
 187                            cs | BCM2835_SPI_CS_TA);
 188                 /* fill in tx fifo as much as possible */
 189                 bcm2835_wr_fifo(bs);
 190         }
 191
 192         /*
 193          * Enable the HW block. This will immediately trigger a DONE (TX
 194          * empty) interrupt, upon which we will fill the TX FIFO with the
 195          * first TX bytes. Pre-filling the TX FIFO here to avoid the
 196          * interrupt doesn't work:-(
 197          */
 198         cs |= BCM2835_SPI_CS_INTR | BCM2835_SPI_CS_INTD | BCM2835_SPI_CS_TA;
 199         bcm2835_wr(bs, BCM2835_SPI_CS, cs);
 200
 201         /* signal that we need to wait for completion */
 202         return 1;
 203 }
 204
 205 /*
 206  * DMA support
 207  *
 208  * this implementation has currently a few issues in so far as it does
 209  * not work arrount limitations of the HW.
 210  *
 211  * the main one being that DMA transfers are limited to 16 bit
 212  * (so 0 to 65535 bytes) by the SPI HW due to BCM2835_SPI_DLEN
 213  *
 214  * also we currently assume that the scatter-gather fragments are
 215  * all multiple of 4 (except the last) - otherwise we would need
 216  * to reset the FIFO before subsequent transfers...
 217  * this also means that tx/rx transfers sg's need to be of equal size!
 218  *
 219  * there may be a few more border-cases we may need to address as well
 220  * but unfortunately this would mean splitting up the scatter-gather
 221  * list making it slightly unpractical...
 222  */
 223 static void bcm2835_spi_dma_done(void *data)
 224 {
 225         struct spi_master *master = data;
 226         struct bcm2835_spi *bs = spi_master_get_devdata(master);
 227
 228         /* reset fifo and HW */
 229         bcm2835_spi_reset_hw(master);
 230
 231         /* and terminate tx-dma as we do not have an irq for it
 232          * because when the rx dma will terminate and this callback
 233          * is called the tx-dma must have finished - can't get to this
 234          * situation otherwise...
 235          */
 236         dmaengine_terminate_all(master->dma_tx);
 237
 238         /* mark as no longer pending */
 239         bs->dma_pending = 0;
 240
 241         /* and mark as completed */;
 242         complete(&master->xfer_completion);
 243 }
 244
 245 static int bcm2835_spi_prepare_sg(struct spi_master *master,
 246                                   struct spi_transfer *tfr,
 247                                   bool is_tx)
 248 {
 249         struct dma_chan *chan;
 250         struct scatterlist *sgl;
 251         unsigned int nents;
 252         enum dma_transfer_direction dir;
 253         unsigned long flags;
 254
 255         struct dma_async_tx_descriptor *desc;
 256         dma_cookie_t cookie;
 257
 258         if (is_tx) {
 259                 dir   = DMA_MEM_TO_DEV;
 260                 chan  = master->dma_tx;
 261                 nents = tfr->tx_sg.nents;
 262                 sgl   = tfr->tx_sg.sgl;
 263                 flags = 0 /* no  tx interrupt */;
 264
 265         } else {
 266                 dir   = DMA_DEV_TO_MEM;
 267                 chan  = master->dma_rx;
 268                 nents = tfr->rx_sg.nents;
 269                 sgl   = tfr->rx_sg.sgl;
 270                 flags = DMA_PREP_INTERRUPT;
 271         }
 272         /* prepare the channel */
 273         desc = dmaengine_prep_slave_sg(chan, sgl, nents, dir, flags);
 274         if (!desc)
 275                 return -EINVAL;
 276
 277         /* set callback for rx */
 278         if (!is_tx) {
 279                 desc->callback = bcm2835_spi_dma_done;
 280                 desc->callback_param = master;
 281         }
 282
 283         /* submit it to DMA-engine */
 284         cookie = dmaengine_submit(desc);
 285
 286         return dma_submit_error(cookie);
 287 }
 288
 289 static inline int bcm2835_check_sg_length(struct sg_table *sgt)
 290 {
 291         int i;
 292         struct scatterlist *sgl;
 293
 294         /* check that the sg entries are word-sized (except for last) */
 295         for_each_sg(sgt->sgl, sgl, (int)sgt->nents - 1, i) {
 296                 if (sg_dma_len(sgl) % 4)
 297                         return -EFAULT;
 298         }
 299
 300         return 0;
 301 }
 302
 303 static int bcm2835_spi_transfer_one_dma(struct spi_master *master,
 304                                         struct spi_device *spi,
 305                                         struct spi_transfer *tfr,
 306                                         u32 cs)
 307 {
 308         struct bcm2835_spi *bs = spi_master_get_devdata(master);
 309         int ret;
 310
 311         /* check that the scatter gather segments are all a multiple of 4 */
 312         if (bcm2835_check_sg_length(&tfr->tx_sg) ||
 313             bcm2835_check_sg_length(&tfr->rx_sg)) {
 314                 dev_warn_once(&spi->dev,
 315                               "scatter gather segment length is not a multiple of 4 - falling back to interrupt mode\n");
 316                 return bcm2835_spi_transfer_one_irq(master, spi, tfr, cs);
 317         }
 318
 319         /* setup tx-DMA */
 320         ret = bcm2835_spi_prepare_sg(master, tfr, true);
 321         if (ret)
 322                 return ret;
 323
 324         /* start TX early */
 325         dma_async_issue_pending(master->dma_tx);
 326
 327         /* mark as dma pending */
 328         bs->dma_pending = 1;
 329
 330         /* set the DMA length */
 331         bcm2835_wr(bs, BCM2835_SPI_DLEN, tfr->len);
 332
 333         /* start the HW */
 334         bcm2835_wr(bs, BCM2835_SPI_CS,
 335                    cs | BCM2835_SPI_CS_TA | BCM2835_SPI_CS_DMAEN);
 336
 337         /* setup rx-DMA late - to run transfers while
 338          * mapping of the rx buffers still takes place
 339          * this saves 10us or more.
 340          */
 341         ret = bcm2835_spi_prepare_sg(master, tfr, false);
 342         if (ret) {
 343                 /* need to reset on errors */
 344                 dmaengine_terminate_all(master->dma_tx);
 345                 bcm2835_spi_reset_hw(master);
 346                 return ret;
 347         }
 348
 349         /* start rx dma late */
 350         dma_async_issue_pending(master->dma_rx);
 351
 352         /* wait for wakeup in framework */
 353         return 1;
 354 }
 355
 356 static bool bcm2835_spi_can_dma(struct spi_master *master,
 357                                 struct spi_device *spi,
 358                                 struct spi_transfer *tfr)
 359 {
 360         /* only run for gpio_cs */
 361         if (!gpio_is_valid(spi->cs_gpio))
 362                 return false;
 363
 364         /* we start DMA efforts only on bigger transfers */
 365         if (tfr->len < BCM2835_SPI_DMA_MIN_LENGTH)
 366                 return false;
 367
 368         /* BCM2835_SPI_DLEN has defined a max transfer size as
 369          * 16 bit, so max is 65535
 370          * we can revisit this by using an alternative transfer
 371          * method - ideally this would get done without any more
 372          * interaction...
 373          */
 374         if (tfr->len > 65535) {
 375                 dev_warn_once(&spi->dev,
 376                               "transfer size of %d too big for dma-transfer\n",
 377                               tfr->len);
 378                 return false;
 379         }
 380
 381         /* if we run rx/tx_buf with word aligned addresses then we are OK */
 382         if ((((size_t)tfr->rx_buf & 3) == 0) &&
 383             (((size_t)tfr->tx_buf & 3) == 0))
 384                 return true;
 385
 386         /* otherwise we only allow transfers within the same page
 387          * to avoid wasting time on dma_mapping when it is not practical
 388          */
 389         if (((size_t)tfr->tx_buf & PAGE_MASK) + tfr->len > PAGE_SIZE) {
 390                 dev_warn_once(&spi->dev,
 391                               "Unaligned spi tx-transfer bridging page\n");
 392                 return false;
 393         }
 394         if (((size_t)tfr->rx_buf & PAGE_MASK) + tfr->len > PAGE_SIZE) {
 395                 dev_warn_once(&spi->dev,
 396                               "Unaligned spi tx-transfer bridging page\n");
 397                 return false;
 398         }
 399
 400         /* return OK */
 401         return true;
 402 }
 403
 404 static void bcm2835_dma_release(struct spi_master *master)
 405 {
 406         if (master->dma_tx) {
 407                 dmaengine_terminate_all(master->dma_tx);
 408                 dma_release_channel(master->dma_tx);
 409                 master->dma_tx = NULL;
 410         }
 411         if (master->dma_rx) {
 412                 dmaengine_terminate_all(master->dma_rx);
 413                 dma_release_channel(master->dma_rx);
 414                 master->dma_rx = NULL;
 415         }
 416 }
 417
 418 static void bcm2835_dma_init(struct spi_master *master, struct device *dev)
 419 {
 420         struct dma_slave_config slave_config;
 421         const __be32 *addr;
 422         dma_addr_t dma_reg_base;
 423         int ret;
 424
 425         /* base address in dma-space */
 426         addr = of_get_address(master->dev.of_node, 0, NULL, NULL);
 427         if (!addr) {
 428                 dev_err(dev, "could not get DMA-register address - not using dma mode\n");
 429                 goto err;
 430         }
 431         dma_reg_base = be32_to_cpup(addr);
 432
 433         /* get tx/rx dma */
 434         master->dma_tx = dma_request_slave_channel(dev, "tx");
 435         if (!master->dma_tx) {
 436                 dev_err(dev, "no tx-dma configuration found - not using dma mode\n");
 437                 goto err;
 438         }
 439         master->dma_rx = dma_request_slave_channel(dev, "rx");
 440         if (!master->dma_rx) {
 441                 dev_err(dev, "no rx-dma configuration found - not using dma mode\n");
 442                 goto err_release;
 443         }
 444
 445         /* configure DMAs */
 446         slave_config.direction = DMA_MEM_TO_DEV;
 447         slave_config.dst_addr = (u32)(dma_reg_base + BCM2835_SPI_FIFO);
 448         slave_config.dst_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES;
 449
 450         ret = dmaengine_slave_config(master->dma_tx, &slave_config);
 451         if (ret)
 452                 goto err_config;
 453
 454         slave_config.direction = DMA_DEV_TO_MEM;
 455         slave_config.src_addr = (u32)(dma_reg_base + BCM2835_SPI_FIFO);
 456         slave_config.src_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES;
 457
 458         ret = dmaengine_slave_config(master->dma_rx, &slave_config);
 459         if (ret)
 460                 goto err_config;
 461
 462         /* all went well, so set can_dma */
 463         master->can_dma = bcm2835_spi_can_dma;
 464         master->max_dma_len = 65535; /* limitation by BCM2835_SPI_DLEN */
 465         /* need to do TX AND RX DMA, so we need dummy buffers */
 466         master->flags = SPI_MASTER_MUST_RX | SPI_MASTER_MUST_TX;
 467
 468         return;
 469
 470 err_config:
 471         dev_err(dev, "issue configuring dma: %d - not using DMA mode\n",
 472                 ret);
 473 err_release:
 474         bcm2835_dma_release(master);
 475 err:
 476         return;
 477 }
 478
 479 static int bcm2835_spi_transfer_one_poll(struct spi_master *master,
 480                                          struct spi_device *spi,
 481                                          struct spi_transfer *tfr,
 482                                          u32 cs,
 483                                          unsigned long xfer_time_us)
 484 {
 485         struct bcm2835_spi *bs = spi_master_get_devdata(master);
 486         unsigned long timeout;
 487
 488         /* enable HW block without interrupts */
 489         bcm2835_wr(bs, BCM2835_SPI_CS, cs | BCM2835_SPI_CS_TA);
 490
 491         /* fill in the fifo before timeout calculations
 492          * if we are interrupted here, then the data is
 493          * getting transferred by the HW while we are interrupted
 494          */
 495         bcm2835_wr_fifo(bs);
 496
 497         /* set the timeout */
 498         timeout = jiffies + BCM2835_SPI_POLLING_JIFFIES;
 499
 500         /* loop until finished the transfer */
 501         while (bs->rx_len) {
 502                 /* fill in tx fifo with remaining data */
 503                 bcm2835_wr_fifo(bs);
 504
 505                 /* read from fifo as much as possible */
 506                 bcm2835_rd_fifo(bs);
 507
 508                 /* if there is still data pending to read
 509                  * then check the timeout
 510                  */
 511                 if (bs->rx_len && time_after(jiffies, timeout)) {
 512                         dev_dbg_ratelimited(&spi->dev,
 513                                             "timeout period reached: jiffies: %lu remaining tx/rx: %d/%d - falling back to interrupt mode\n",
 514                                             jiffies - timeout,
 515                                             bs->tx_len, bs->rx_len);
 516                         /* fall back to interrupt mode */
 517                         return bcm2835_spi_transfer_one_irq(master, spi,
 518                                                             tfr, cs);
 519                 }
 520         }
 521
 522         /* Transfer complete - reset SPI HW */
 523         bcm2835_spi_reset_hw(master);
 524         /* and return without waiting for completion */
 525         return 0;
 526 }
 527
 528 static int bcm2835_spi_transfer_one(struct spi_master *master,
 529                                     struct spi_device *spi,
 530                                     struct spi_transfer *tfr)
 531 {
 532         struct bcm2835_spi *bs = spi_master_get_devdata(master);
 533         unsigned long spi_hz, clk_hz, cdiv;
 534         unsigned long spi_used_hz, xfer_time_us;
 535         u32 cs = bcm2835_rd(bs, BCM2835_SPI_CS);
 536
 537         /* set clock */
 538         spi_hz = tfr->speed_hz;
 539         clk_hz = clk_get_rate(bs->clk);
 540
 541         if (spi_hz >= clk_hz / 2) {
 542                 cdiv = 2; /* clk_hz/2 is the fastest we can go */
 543         } else if (spi_hz) {
 544                 /* CDIV must be a multiple of two */
 545                 cdiv = DIV_ROUND_UP(clk_hz, spi_hz);
 546                 cdiv += (cdiv % 2);
 547
 548                 if (cdiv >= 65536)
 549                         cdiv = 0; /* 0 is the slowest we can go */
 550         } else {
 551                 cdiv = 0; /* 0 is the slowest we can go */
 552         }
 553         spi_used_hz = cdiv ? (clk_hz / cdiv) : (clk_hz / 65536);
 554         bcm2835_wr(bs, BCM2835_SPI_CLK, cdiv);
 555
 556         /* handle all the modes */
 557         if ((spi->mode & SPI_3WIRE) && (tfr->rx_buf))
 558                 cs |= BCM2835_SPI_CS_REN;
 559         if (spi->mode & SPI_CPOL)
 560                 cs |= BCM2835_SPI_CS_CPOL;
 561         if (spi->mode & SPI_CPHA)
 562                 cs |= BCM2835_SPI_CS_CPHA;
 563
 564         /* for gpio_cs set dummy CS so that no HW-CS get changed
 565          * we can not run this in bcm2835_spi_set_cs, as it does
 566          * not get called for cs_gpio cases, so we need to do it here
 567          */
 568         if (gpio_is_valid(spi->cs_gpio) || (spi->mode & SPI_NO_CS))
 569                 cs |= BCM2835_SPI_CS_CS_10 | BCM2835_SPI_CS_CS_01;
 570
 571         /* set transmit buffers and length */
 572         bs->tx_buf = tfr->tx_buf;
 573         bs->rx_buf = tfr->rx_buf;
 574         bs->tx_len = tfr->len;
 575         bs->rx_len = tfr->len;
 576
 577         /* calculate the estimated time in us the transfer runs */
 578         xfer_time_us = tfr->len
 579                 * 9 /* clocks/byte - SPI-HW waits 1 clock after each byte */
 580                 * 1000000 / spi_used_hz;
 581
 582         /* for short requests run polling*/
 583         if (xfer_time_us <= BCM2835_SPI_POLLING_LIMIT_US)
 584                 return bcm2835_spi_transfer_one_poll(master, spi, tfr,
 585                                                      cs, xfer_time_us);
 586
 587         /* run in dma mode if conditions are right */
 588         if (master->can_dma && bcm2835_spi_can_dma(master, spi, tfr))
 589                 return bcm2835_spi_transfer_one_dma(master, spi, tfr, cs);
 590
 591         /* run in interrupt-mode */
 592         return bcm2835_spi_transfer_one_irq(master, spi, tfr, cs);
 593 }
 594
 595 static void bcm2835_spi_handle_err(struct spi_master *master,
 596                                    struct spi_message *msg)
 597 {
 598         struct bcm2835_spi *bs = spi_master_get_devdata(master);
 599
 600         /* if an error occurred and we have an active dma, then terminate */
 601         if (bs->dma_pending) {
 602                 dmaengine_terminate_all(master->dma_tx);
 603                 dmaengine_terminate_all(master->dma_rx);
 604                 bs->dma_pending = 0;
 605         }
 606         /* and reset */
 607         bcm2835_spi_reset_hw(master);
 608 }
 609
 610 static void bcm2835_spi_set_cs(struct spi_device *spi, bool gpio_level)
 611 {
 612         /*
 613          * we can assume that we are "native" as per spi_set_cs
 614          *   calling us ONLY when cs_gpio is not set
 615          * we can also assume that we are CS < 3 as per bcm2835_spi_setup
 616          *   we would not get called because of error handling there.
 617          * the level passed is the electrical level not enabled/disabled
 618          *   so it has to get translated back to enable/disable
 619          *   see spi_set_cs in spi.c for the implementation
 620          */
 621
 622         struct spi_master *master = spi->master;
 623         struct bcm2835_spi *bs = spi_master_get_devdata(master);
 624         u32 cs = bcm2835_rd(bs, BCM2835_SPI_CS);
 625         bool enable;
 626
 627         /* calculate the enable flag from the passed gpio_level */
 628         enable = (spi->mode & SPI_CS_HIGH) ? gpio_level : !gpio_level;
 629
 630         /* set flags for "reverse" polarity in the registers */
 631         if (spi->mode & SPI_CS_HIGH) {
 632                 /* set the correct CS-bits */
 633                 cs |= BCM2835_SPI_CS_CSPOL;
 634                 cs |= BCM2835_SPI_CS_CSPOL0 << spi->chip_select;
 635         } else {
 636                 /* clean the CS-bits */
 637                 cs &= ~BCM2835_SPI_CS_CSPOL;
 638                 cs &= ~(BCM2835_SPI_CS_CSPOL0 << spi->chip_select);
 639         }
 640
 641         /* select the correct chip_select depending on disabled/enabled */
 642         if (enable) {
 643                 /* set cs correctly */
 644                 if (spi->mode & SPI_NO_CS) {
 645                         /* use the "undefined" chip-select */
 646                         cs |= BCM2835_SPI_CS_CS_10 | BCM2835_SPI_CS_CS_01;
 647                 } else {
 648                         /* set the chip select */
 649                         cs &= ~(BCM2835_SPI_CS_CS_10 | BCM2835_SPI_CS_CS_01);
 650                         cs |= spi->chip_select;
 651                 }
 652         } else {
 653                 /* disable CSPOL which puts HW-CS into deselected state */
 654                 cs &= ~BCM2835_SPI_CS_CSPOL;
 655                 /* use the "undefined" chip-select as precaution */
 656                 cs |= BCM2835_SPI_CS_CS_10 | BCM2835_SPI_CS_CS_01;
 657         }
 658
 659         /* finally set the calculated flags in SPI_CS */
 660         bcm2835_wr(bs, BCM2835_SPI_CS, cs);
 661 }
 662
 663 static int chip_match_name(struct gpio_chip *chip, void *data)
 664 {
 665         return !strcmp(chip->label, data);
 666 }
 667
 668 static int bcm2835_spi_setup(struct spi_device *spi)
 669 {
 670         int err;
 671         struct gpio_chip *chip;
 672         /*
 673          * sanity checking the native-chipselects
 674          */
 675         if (spi->mode & SPI_NO_CS)
 676                 return 0;
 677         if (gpio_is_valid(spi->cs_gpio))
 678                 return 0;
 679         if (spi->chip_select > 1) {
 680                 /* error in the case of native CS requested with CS > 1
 681                  * officially there is a CS2, but it is not documented
 682                  * which GPIO is connected with that...
 683                  */
 684                 dev_err(&spi->dev,
 685                         "setup: only two native chip-selects are supported\n");
 686                 return -EINVAL;
 687         }
 688         /* now translate native cs to GPIO */
 689
 690         /* get the gpio chip for the base */
 691         chip = gpiochip_find("pinctrl-bcm2835", chip_match_name);
 692         if (!chip)
 693                 return 0;
 694
 695         /* and calculate the real CS */
 696         spi->cs_gpio = chip->base + 8 - spi->chip_select;
 697
 698         /* and set up the "mode" and level */
 699         dev_info(&spi->dev, "setting up native-CS%i as GPIO %i\n",
 700                  spi->chip_select, spi->cs_gpio);
 701
 702         /* set up GPIO as output and pull to the correct level */
 703         err = gpio_direction_output(spi->cs_gpio,
 704                                     (spi->mode & SPI_CS_HIGH) ? 0 : 1);
 705         if (err) {
 706                 dev_err(&spi->dev,
 707                         "could not set CS%i gpio %i as output: %i",
 708                         spi->chip_select, spi->cs_gpio, err);
 709                 return err;
 710         }
 711         /* the implementation of pinctrl-bcm2835 currently does not
 712          * set the GPIO value when using gpio_direction_output
 713          * so we are setting it here explicitly
 714          */
 715         gpio_set_value(spi->cs_gpio, (spi->mode & SPI_CS_HIGH) ? 0 : 1);
 716
 717         return 0;
 718 }
 719
 720 static int bcm2835_spi_probe(struct platform_device *pdev)
 721 {
 722         struct spi_master *master;
 723         struct bcm2835_spi *bs;
 724         struct resource *res;
 725         int err;
 726
 727         master = spi_alloc_master(&pdev->dev, sizeof(*bs));
 728         if (!master) {
 729                 dev_err(&pdev->dev, "spi_alloc_master() failed\n");
 730                 return -ENOMEM;
 731         }
 732
 733         platform_set_drvdata(pdev, master);
 734
 735         master->mode_bits = BCM2835_SPI_MODE_BITS;
 736         master->bits_per_word_mask = SPI_BPW_MASK(8);
 737         master->num_chipselect = 3;
 738         master->setup = bcm2835_spi_setup;
 739         master->set_cs = bcm2835_spi_set_cs;
 740         master->transfer_one = bcm2835_spi_transfer_one;
 741         master->handle_err = bcm2835_spi_handle_err;
 742         master->dev.of_node = pdev->dev.of_node;
 743
 744         bs = spi_master_get_devdata(master);
 745
 746         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 747         bs->regs = devm_ioremap_resource(&pdev->dev, res);
 748         if (IS_ERR(bs->regs)) {
 749                 err = PTR_ERR(bs->regs);
 750                 goto out_master_put;
 751         }
 752
 753         bs->clk = devm_clk_get(&pdev->dev, NULL);
 754         if (IS_ERR(bs->clk)) {
 755                 err = PTR_ERR(bs->clk);
 756                 dev_err(&pdev->dev, "could not get clk: %d\n", err);
 757                 goto out_master_put;
 758         }
 759
 760         bs->irq = irq_of_parse_and_map(pdev->dev.of_node, 0);
 761         if (bs->irq <= 0) {
 762                 dev_err(&pdev->dev, "could not get IRQ: %d\n", bs->irq);
 763                 err = bs->irq ? bs->irq : -ENODEV;
 764                 goto out_master_put;
 765         }
 766
 767         clk_prepare_enable(bs->clk);
 768
 769         err = devm_request_irq(&pdev->dev, bs->irq, bcm2835_spi_interrupt, 0,
 770                                dev_name(&pdev->dev), master);
 771         if (err) {
 772                 dev_err(&pdev->dev, "could not request IRQ: %d\n", err);
 773                 goto out_clk_disable;
 774         }
 775
 776         bcm2835_dma_init(master, &pdev->dev);
 777
 778         /* initialise the hardware with the default polarities */
 779         bcm2835_wr(bs, BCM2835_SPI_CS,
 780                    BCM2835_SPI_CS_CLEAR_RX | BCM2835_SPI_CS_CLEAR_TX);
 781
 782         err = devm_spi_register_master(&pdev->dev, master);
 783         if (err) {
 784                 dev_err(&pdev->dev, "could not register SPI master: %d\n", err);
 785                 goto out_clk_disable;
 786         }
 787
 788         return 0;
 789
 790 out_clk_disable:
 791         clk_disable_unprepare(bs->clk);
 792 out_master_put:
 793         spi_master_put(master);
 794         return err;
 795 }
 796
 797 static int bcm2835_spi_remove(struct platform_device *pdev)
 798 {
 799         struct spi_master *master = platform_get_drvdata(pdev);
 800         struct bcm2835_spi *bs = spi_master_get_devdata(master);
 801
 802         /* Clear FIFOs, and disable the HW block */
 803         bcm2835_wr(bs, BCM2835_SPI_CS,
 804                    BCM2835_SPI_CS_CLEAR_RX | BCM2835_SPI_CS_CLEAR_TX);
 805
 806         clk_disable_unprepare(bs->clk);
 807
 808         bcm2835_dma_release(master);
 809
 810         return 0;
 811 }
 812
 813 static const struct of_device_id bcm2835_spi_match[] = {
 814         { .compatible = "brcm,bcm2835-spi", },
 815         {}
 816 };
 817 MODULE_DEVICE_TABLE(of, bcm2835_spi_match);
 818
 819 static struct platform_driver bcm2835_spi_driver = {
 820         .driver         = {
 821                 .name           = DRV_NAME,
 822                 .of_match_table = bcm2835_spi_match,
 823         },
 824         .probe          = bcm2835_spi_probe,
 825         .remove         = bcm2835_spi_remove,
 826 };
 827 module_platform_driver(bcm2835_spi_driver);
 828
 829 MODULE_DESCRIPTION("SPI controller driver for Broadcom BCM2835");
 830 MODULE_AUTHOR("Chris Boot <bootc@bootc.net>");
 831 MODULE_LICENSE("GPL v2");