drivers/mmc/host/litex_mmc.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * LiteX LiteSDCard driver
   4  *
   5  * Copyright (C) 2019-2020 Antmicro <contact@antmicro.com>
   6  * Copyright (C) 2019-2020 Kamil Rakoczy <krakoczy@antmicro.com>
   7  * Copyright (C) 2019-2020 Maciej Dudek <mdudek@internships.antmicro.com>
   8  * Copyright (C) 2020 Paul Mackerras <paulus@ozlabs.org>
   9  * Copyright (C) 2020-2022 Gabriel Somlo <gsomlo@gmail.com>
  10  */
  11
  12 #include <linux/bits.h>
  13 #include <linux/clk.h>
  14 #include <linux/delay.h>
  15 #include <linux/dma-mapping.h>
  16 #include <linux/interrupt.h>
  17 #include <linux/iopoll.h>
  18 #include <linux/litex.h>
  19 #include <linux/mod_devicetable.h>
  20 #include <linux/module.h>
  21 #include <linux/platform_device.h>
  22
  23 #include <linux/mmc/host.h>
  24 #include <linux/mmc/mmc.h>
  25 #include <linux/mmc/sd.h>
  26
  27 #define LITEX_PHY_CARDDETECT  0x00
  28 #define LITEX_PHY_CLOCKERDIV  0x04
  29 #define LITEX_PHY_INITIALIZE  0x08
  30 #define LITEX_PHY_WRITESTATUS 0x0C
  31 #define LITEX_CORE_CMDARG     0x00
  32 #define LITEX_CORE_CMDCMD     0x04
  33 #define LITEX_CORE_CMDSND     0x08
  34 #define LITEX_CORE_CMDRSP     0x0C
  35 #define LITEX_CORE_CMDEVT     0x1C
  36 #define LITEX_CORE_DATEVT     0x20
  37 #define LITEX_CORE_BLKLEN     0x24
  38 #define LITEX_CORE_BLKCNT     0x28
  39 #define LITEX_BLK2MEM_BASE    0x00
  40 #define LITEX_BLK2MEM_LEN     0x08
  41 #define LITEX_BLK2MEM_ENA     0x0C
  42 #define LITEX_BLK2MEM_DONE    0x10
  43 #define LITEX_BLK2MEM_LOOP    0x14
  44 #define LITEX_MEM2BLK_BASE    0x00
  45 #define LITEX_MEM2BLK_LEN     0x08
  46 #define LITEX_MEM2BLK_ENA     0x0C
  47 #define LITEX_MEM2BLK_DONE    0x10
  48 #define LITEX_MEM2BLK_LOOP    0x14
  49 #define LITEX_MEM2BLK         0x18
  50 #define LITEX_IRQ_STATUS      0x00
  51 #define LITEX_IRQ_PENDING     0x04
  52 #define LITEX_IRQ_ENABLE      0x08
  53
  54 #define SD_CTL_DATA_XFER_NONE  0
  55 #define SD_CTL_DATA_XFER_READ  1
  56 #define SD_CTL_DATA_XFER_WRITE 2
  57
  58 #define SD_CTL_RESP_NONE       0
  59 #define SD_CTL_RESP_SHORT      1
  60 #define SD_CTL_RESP_LONG       2
  61 #define SD_CTL_RESP_SHORT_BUSY 3
  62
  63 #define SD_BIT_DONE    BIT(0)
  64 #define SD_BIT_WR_ERR  BIT(1)
  65 #define SD_BIT_TIMEOUT BIT(2)
  66 #define SD_BIT_CRC_ERR BIT(3)
  67
  68 #define SD_SLEEP_US       5
  69 #define SD_TIMEOUT_US 20000
  70
  71 #define SDIRQ_CARD_DETECT    1
  72 #define SDIRQ_SD_TO_MEM_DONE 2
  73 #define SDIRQ_MEM_TO_SD_DONE 4
  74 #define SDIRQ_CMD_DONE       8
  75
  76 struct litex_mmc_host {
  77         struct mmc_host *mmc;
  78
  79         void __iomem *sdphy;
  80         void __iomem *sdcore;
  81         void __iomem *sdreader;
  82         void __iomem *sdwriter;
  83         void __iomem *sdirq;
  84
  85         void *buffer;
  86         size_t buf_size;
  87         dma_addr_t dma;
  88
  89         struct completion cmd_done;
  90         int irq;
  91
  92         unsigned int ref_clk;
  93         unsigned int sd_clk;
  94
  95         u32 resp[4];
  96         u16 rca;
  97
  98         bool is_bus_width_set;
  99         bool app_cmd;
 100 };
 101
 102 static int litex_mmc_sdcard_wait_done(void __iomem *reg, struct device *dev)
 103 {
 104         u8 evt;
 105         int ret;
 106
 107         ret = readx_poll_timeout(litex_read8, reg, evt, evt & SD_BIT_DONE,
 108                                  SD_SLEEP_US, SD_TIMEOUT_US);
 109         if (ret)
 110                 return ret;
 111         if (evt == SD_BIT_DONE)
 112                 return 0;
 113         if (evt & SD_BIT_WR_ERR)
 114                 return -EIO;
 115         if (evt & SD_BIT_TIMEOUT)
 116                 return -ETIMEDOUT;
 117         if (evt & SD_BIT_CRC_ERR)
 118                 return -EILSEQ;
 119         dev_err(dev, "%s: unknown error (evt=%x)\n", __func__, evt);
 120         return -EINVAL;
 121 }
 122
 123 static int litex_mmc_send_cmd(struct litex_mmc_host *host,
 124                               u8 cmd, u32 arg, u8 response_len, u8 transfer)
 125 {
 126         struct device *dev = mmc_dev(host->mmc);
 127         void __iomem *reg;
 128         int ret;
 129         u8 evt;
 130
 131         litex_write32(host->sdcore + LITEX_CORE_CMDARG, arg);
 132         litex_write32(host->sdcore + LITEX_CORE_CMDCMD,
 133                       cmd << 8 | transfer << 5 | response_len);
 134         litex_write8(host->sdcore + LITEX_CORE_CMDSND, 1);
 135
 136         /*
 137          * Wait for an interrupt if we have an interrupt and either there is
 138          * data to be transferred, or if the card can report busy via DAT0.
 139          */
 140         if (host->irq > 0 &&
 141             (transfer != SD_CTL_DATA_XFER_NONE ||
 142              response_len == SD_CTL_RESP_SHORT_BUSY)) {
 143                 reinit_completion(&host->cmd_done);
 144                 litex_write32(host->sdirq + LITEX_IRQ_ENABLE,
 145                               SDIRQ_CMD_DONE | SDIRQ_CARD_DETECT);
 146                 wait_for_completion(&host->cmd_done);
 147         }
 148
 149         ret = litex_mmc_sdcard_wait_done(host->sdcore + LITEX_CORE_CMDEVT, dev);
 150         if (ret) {
 151                 dev_err(dev, "Command (cmd %d) error, status %d\n", cmd, ret);
 152                 return ret;
 153         }
 154
 155         if (response_len != SD_CTL_RESP_NONE) {
 156                 /*
 157                  * NOTE: this matches the semantics of litex_read32()
 158                  * regardless of underlying arch endianness!
 159                  */
 160                 memcpy_fromio(host->resp,
 161                               host->sdcore + LITEX_CORE_CMDRSP, 0x10);
 162         }
 163
 164         if (!host->app_cmd && cmd == SD_SEND_RELATIVE_ADDR)
 165                 host->rca = (host->resp[3] >> 16);
 166
 167         host->app_cmd = (cmd == MMC_APP_CMD);
 168
 169         if (transfer == SD_CTL_DATA_XFER_NONE)
 170                 return ret; /* OK from prior litex_mmc_sdcard_wait_done() */
 171
 172         ret = litex_mmc_sdcard_wait_done(host->sdcore + LITEX_CORE_DATEVT, dev);
 173         if (ret) {
 174                 dev_err(dev, "Data xfer (cmd %d) error, status %d\n", cmd, ret);
 175                 return ret;
 176         }
 177
 178         /* Wait for completion of (read or write) DMA transfer */
 179         reg = (transfer == SD_CTL_DATA_XFER_READ) ?
 180                 host->sdreader + LITEX_BLK2MEM_DONE :
 181                 host->sdwriter + LITEX_MEM2BLK_DONE;
 182         ret = readx_poll_timeout(litex_read8, reg, evt, evt & SD_BIT_DONE,
 183                                  SD_SLEEP_US, SD_TIMEOUT_US);
 184         if (ret)
 185                 dev_err(dev, "DMA timeout (cmd %d)\n", cmd);
 186
 187         return ret;
 188 }
 189
 190 static int litex_mmc_send_app_cmd(struct litex_mmc_host *host)
 191 {
 192         return litex_mmc_send_cmd(host, MMC_APP_CMD, host->rca << 16,
 193                                   SD_CTL_RESP_SHORT, SD_CTL_DATA_XFER_NONE);
 194 }
 195
 196 static int litex_mmc_send_set_bus_w_cmd(struct litex_mmc_host *host, u32 width)
 197 {
 198         return litex_mmc_send_cmd(host, SD_APP_SET_BUS_WIDTH, width,
 199                                   SD_CTL_RESP_SHORT, SD_CTL_DATA_XFER_NONE);
 200 }
 201
 202 static int litex_mmc_set_bus_width(struct litex_mmc_host *host)
 203 {
 204         bool app_cmd_sent;
 205         int ret;
 206
 207         if (host->is_bus_width_set)
 208                 return 0;
 209
 210         /* Ensure 'app_cmd' precedes 'app_set_bus_width_cmd' */
 211         app_cmd_sent = host->app_cmd; /* was preceding command app_cmd? */
 212         if (!app_cmd_sent) {
 213                 ret = litex_mmc_send_app_cmd(host);
 214                 if (ret)
 215                         return ret;
 216         }
 217
 218         /* LiteSDCard only supports 4-bit bus width */
 219         ret = litex_mmc_send_set_bus_w_cmd(host, MMC_BUS_WIDTH_4);
 220         if (ret)
 221                 return ret;
 222
 223         /* Re-send 'app_cmd' if necessary */
 224         if (app_cmd_sent) {
 225                 ret = litex_mmc_send_app_cmd(host);
 226                 if (ret)
 227                         return ret;
 228         }
 229
 230         host->is_bus_width_set = true;
 231
 232         return 0;
 233 }
 234
 235 static int litex_mmc_get_cd(struct mmc_host *mmc)
 236 {
 237         struct litex_mmc_host *host = mmc_priv(mmc);
 238         int ret;
 239
 240         if (!mmc_card_is_removable(mmc))
 241                 return 1;
 242
 243         ret = !litex_read8(host->sdphy + LITEX_PHY_CARDDETECT);
 244         if (ret)
 245                 return ret;
 246
 247         /* Ensure bus width will be set (again) upon card (re)insertion */
 248         host->is_bus_width_set = false;
 249
 250         return 0;
 251 }
 252
 253 static irqreturn_t litex_mmc_interrupt(int irq, void *arg)
 254 {
 255         struct mmc_host *mmc = arg;
 256         struct litex_mmc_host *host = mmc_priv(mmc);
 257         u32 pending = litex_read32(host->sdirq + LITEX_IRQ_PENDING);
 258         irqreturn_t ret = IRQ_NONE;
 259
 260         /* Check for card change interrupt */
 261         if (pending & SDIRQ_CARD_DETECT) {
 262                 litex_write32(host->sdirq + LITEX_IRQ_PENDING,
 263                               SDIRQ_CARD_DETECT);
 264                 mmc_detect_change(mmc, msecs_to_jiffies(10));
 265                 ret = IRQ_HANDLED;
 266         }
 267
 268         /* Check for command completed */
 269         if (pending & SDIRQ_CMD_DONE) {
 270                 /* Disable it so it doesn't keep interrupting */
 271                 litex_write32(host->sdirq + LITEX_IRQ_ENABLE,
 272                               SDIRQ_CARD_DETECT);
 273                 complete(&host->cmd_done);
 274                 ret = IRQ_HANDLED;
 275         }
 276
 277         return ret;
 278 }
 279
 280 static u32 litex_mmc_response_len(struct mmc_command *cmd)
 281 {
 282         if (cmd->flags & MMC_RSP_136)
 283                 return SD_CTL_RESP_LONG;
 284         if (!(cmd->flags & MMC_RSP_PRESENT))
 285                 return SD_CTL_RESP_NONE;
 286         if (cmd->flags & MMC_RSP_BUSY)
 287                 return SD_CTL_RESP_SHORT_BUSY;
 288         return SD_CTL_RESP_SHORT;
 289 }
 290
 291 static void litex_mmc_do_dma(struct litex_mmc_host *host, struct mmc_data *data,
 292                              unsigned int *len, bool *direct, u8 *transfer)
 293 {
 294         struct device *dev = mmc_dev(host->mmc);
 295         dma_addr_t dma;
 296         int sg_count;
 297
 298         /*
 299          * Try to DMA directly to/from the data buffer.
 300          * We can do that if the buffer can be mapped for DMA
 301          * in one contiguous chunk.
 302          */
 303         dma = host->dma;
 304         *len = data->blksz * data->blocks;
 305         sg_count = dma_map_sg(dev, data->sg, data->sg_len,
 306                               mmc_get_dma_dir(data));
 307         if (sg_count == 1) {
 308                 dma = sg_dma_address(data->sg);
 309                 *len = sg_dma_len(data->sg);
 310                 *direct = true;
 311         } else if (*len > host->buf_size)
 312                 *len = host->buf_size;
 313
 314         if (data->flags & MMC_DATA_READ) {
 315                 litex_write8(host->sdreader + LITEX_BLK2MEM_ENA, 0);
 316                 litex_write64(host->sdreader + LITEX_BLK2MEM_BASE, dma);
 317                 litex_write32(host->sdreader + LITEX_BLK2MEM_LEN, *len);
 318                 litex_write8(host->sdreader + LITEX_BLK2MEM_ENA, 1);
 319                 *transfer = SD_CTL_DATA_XFER_READ;
 320         } else if (data->flags & MMC_DATA_WRITE) {
 321                 if (!*direct)
 322                         sg_copy_to_buffer(data->sg, data->sg_len,
 323                                           host->buffer, *len);
 324                 litex_write8(host->sdwriter + LITEX_MEM2BLK_ENA, 0);
 325                 litex_write64(host->sdwriter + LITEX_MEM2BLK_BASE, dma);
 326                 litex_write32(host->sdwriter + LITEX_MEM2BLK_LEN, *len);
 327                 litex_write8(host->sdwriter + LITEX_MEM2BLK_ENA, 1);
 328                 *transfer = SD_CTL_DATA_XFER_WRITE;
 329         } else {
 330                 dev_warn(dev, "Data present w/o read or write flag.\n");
 331                 /* Continue: set cmd status, mark req done */
 332         }
 333
 334         litex_write16(host->sdcore + LITEX_CORE_BLKLEN, data->blksz);
 335         litex_write32(host->sdcore + LITEX_CORE_BLKCNT, data->blocks);
 336 }
 337
 338 static void litex_mmc_request(struct mmc_host *mmc, struct mmc_request *mrq)
 339 {
 340         struct litex_mmc_host *host = mmc_priv(mmc);
 341         struct device *dev = mmc_dev(mmc);
 342         struct mmc_command *cmd = mrq->cmd;
 343         struct mmc_command *sbc = mrq->sbc;
 344         struct mmc_data *data = mrq->data;
 345         struct mmc_command *stop = mrq->stop;
 346         unsigned int retries = cmd->retries;
 347         unsigned int len = 0;
 348         bool direct = false;
 349         u32 response_len = litex_mmc_response_len(cmd);
 350         u8 transfer = SD_CTL_DATA_XFER_NONE;
 351
 352         /* First check that the card is still there */
 353         if (!litex_mmc_get_cd(mmc)) {
 354                 cmd->error = -ENOMEDIUM;
 355                 mmc_request_done(mmc, mrq);
 356                 return;
 357         }
 358
 359         /* Send set-block-count command if needed */
 360         if (sbc) {
 361                 sbc->error = litex_mmc_send_cmd(host, sbc->opcode, sbc->arg,
 362                                                 litex_mmc_response_len(sbc),
 363                                                 SD_CTL_DATA_XFER_NONE);
 364                 if (sbc->error) {
 365                         host->is_bus_width_set = false;
 366                         mmc_request_done(mmc, mrq);
 367                         return;
 368                 }
 369         }
 370
 371         if (data) {
 372                 /*
 373                  * LiteSDCard only supports 4-bit bus width; therefore, we MUST
 374                  * inject a SET_BUS_WIDTH (acmd6) before the very first data
 375                  * transfer, earlier than when the mmc subsystem would normally
 376                  * get around to it!
 377                  */
 378                 cmd->error = litex_mmc_set_bus_width(host);
 379                 if (cmd->error) {
 380                         dev_err(dev, "Can't set bus width!\n");
 381                         mmc_request_done(mmc, mrq);
 382                         return;
 383                 }
 384
 385                 litex_mmc_do_dma(host, data, &len, &direct, &transfer);
 386         }
 387
 388         do {
 389                 cmd->error = litex_mmc_send_cmd(host, cmd->opcode, cmd->arg,
 390                                                 response_len, transfer);
 391         } while (cmd->error && retries-- > 0);
 392
 393         if (cmd->error) {
 394                 /* Card may be gone; don't assume bus width is still set */
 395                 host->is_bus_width_set = false;
 396         }
 397
 398         if (response_len == SD_CTL_RESP_SHORT) {
 399                 /* Pull short response fields from appropriate host registers */
 400                 cmd->resp[0] = host->resp[3];
 401                 cmd->resp[1] = host->resp[2] & 0xFF;
 402         } else if (response_len == SD_CTL_RESP_LONG) {
 403                 cmd->resp[0] = host->resp[0];
 404                 cmd->resp[1] = host->resp[1];
 405                 cmd->resp[2] = host->resp[2];
 406                 cmd->resp[3] = host->resp[3];
 407         }
 408
 409         /* Send stop-transmission command if required */
 410         if (stop && (cmd->error || !sbc)) {
 411                 stop->error = litex_mmc_send_cmd(host, stop->opcode, stop->arg,
 412                                                  litex_mmc_response_len(stop),
 413                                                  SD_CTL_DATA_XFER_NONE);
 414                 if (stop->error)
 415                         host->is_bus_width_set = false;
 416         }
 417
 418         if (data) {
 419                 dma_unmap_sg(dev, data->sg, data->sg_len,
 420                              mmc_get_dma_dir(data));
 421         }
 422
 423         if (!cmd->error && transfer != SD_CTL_DATA_XFER_NONE) {
 424                 data->bytes_xfered = min(len, mmc->max_req_size);
 425                 if (transfer == SD_CTL_DATA_XFER_READ && !direct) {
 426                         sg_copy_from_buffer(data->sg, sg_nents(data->sg),
 427                                             host->buffer, data->bytes_xfered);
 428                 }
 429         }
 430
 431         mmc_request_done(mmc, mrq);
 432 }
 433
 434 static void litex_mmc_setclk(struct litex_mmc_host *host, unsigned int freq)
 435 {
 436         struct device *dev = mmc_dev(host->mmc);
 437         u32 div;
 438
 439         div = freq ? host->ref_clk / freq : 256U;
 440         div = roundup_pow_of_two(div);
 441         div = clamp(div, 2U, 256U);
 442         dev_dbg(dev, "sd_clk_freq=%d: set to %d via div=%d\n",
 443                 freq, host->ref_clk / div, div);
 444         litex_write16(host->sdphy + LITEX_PHY_CLOCKERDIV, div);
 445         host->sd_clk = freq;
 446 }
 447
 448 static void litex_mmc_set_ios(struct mmc_host *mmc, struct mmc_ios *ios)
 449 {
 450         struct litex_mmc_host *host = mmc_priv(mmc);
 451
 452         /*
 453          * NOTE: Ignore any ios->bus_width updates; they occur right after
 454          * the mmc core sends its own acmd6 bus-width change notification,
 455          * which is redundant since we snoop on the command flow and inject
 456          * an early acmd6 before the first data transfer command is sent!
 457          */
 458
 459         /* Update sd_clk */
 460         if (ios->clock != host->sd_clk)
 461                 litex_mmc_setclk(host, ios->clock);
 462 }
 463
 464 static const struct mmc_host_ops litex_mmc_ops = {
 465         .get_cd = litex_mmc_get_cd,
 466         .request = litex_mmc_request,
 467         .set_ios = litex_mmc_set_ios,
 468 };
 469
 470 static int litex_mmc_irq_init(struct platform_device *pdev,
 471                               struct litex_mmc_host *host)
 472 {
 473         struct device *dev = mmc_dev(host->mmc);
 474         int ret;
 475
 476         ret = platform_get_irq_optional(pdev, 0);
 477         if (ret < 0 && ret != -ENXIO)
 478                 return ret;
 479         if (ret > 0)
 480                 host->irq = ret;
 481         else {
 482                 dev_warn(dev, "Failed to get IRQ, using polling\n");
 483                 goto use_polling;
 484         }
 485
 486         host->sdirq = devm_platform_ioremap_resource_byname(pdev, "irq");
 487         if (IS_ERR(host->sdirq))
 488                 return PTR_ERR(host->sdirq);
 489
 490         ret = devm_request_irq(dev, host->irq, litex_mmc_interrupt, 0,
 491                                "litex-mmc", host->mmc);
 492         if (ret < 0) {
 493                 dev_warn(dev, "IRQ request error %d, using polling\n", ret);
 494                 goto use_polling;
 495         }
 496
 497         /* Clear & enable card-change interrupts */
 498         litex_write32(host->sdirq + LITEX_IRQ_PENDING, SDIRQ_CARD_DETECT);
 499         litex_write32(host->sdirq + LITEX_IRQ_ENABLE, SDIRQ_CARD_DETECT);
 500
 501         return 0;
 502
 503 use_polling:
 504         host->mmc->caps |= MMC_CAP_NEEDS_POLL;
 505         return 0;
 506 }
 507
 508 static void litex_mmc_free_host_wrapper(void *mmc)
 509 {
 510         mmc_free_host(mmc);
 511 }
 512
 513 static int litex_mmc_probe(struct platform_device *pdev)
 514 {
 515         struct device *dev = &pdev->dev;
 516         struct litex_mmc_host *host;
 517         struct mmc_host *mmc;
 518         struct clk *clk;
 519         int ret;
 520
 521         /*
 522          * NOTE: defaults to max_[req,seg]_size=PAGE_SIZE, max_blk_size=512,
 523          * and max_blk_count accordingly set to 8;
 524          * If for some reason we need to modify max_blk_count, we must also
 525          * re-calculate `max_[req,seg]_size = max_blk_size * max_blk_count;`
 526          */
 527         mmc = mmc_alloc_host(sizeof(struct litex_mmc_host), dev);
 528         if (!mmc)
 529                 return -ENOMEM;
 530
 531         ret = devm_add_action_or_reset(dev, litex_mmc_free_host_wrapper, mmc);
 532         if (ret)
 533                 return dev_err_probe(dev, ret,
 534                                      "Can't register mmc_free_host action\n");
 535
 536         host = mmc_priv(mmc);
 537         host->mmc = mmc;
 538
 539         /* Initialize clock source */
 540         clk = devm_clk_get(dev, NULL);
 541         if (IS_ERR(clk))
 542                 return dev_err_probe(dev, PTR_ERR(clk), "can't get clock\n");
 543         host->ref_clk = clk_get_rate(clk);
 544         host->sd_clk = 0;
 545
 546         /*
 547          * LiteSDCard only supports 4-bit bus width; therefore, we MUST inject
 548          * a SET_BUS_WIDTH (acmd6) before the very first data transfer, earlier
 549          * than when the mmc subsystem would normally get around to it!
 550          */
 551         host->is_bus_width_set = false;
 552         host->app_cmd = false;
 553
 554         /* LiteSDCard can support 64-bit DMA addressing */
 555         ret = dma_set_mask_and_coherent(dev, DMA_BIT_MASK(64));
 556         if (ret)
 557                 return ret;
 558
 559         host->buf_size = mmc->max_req_size * 2;
 560         host->buffer = dmam_alloc_coherent(dev, host->buf_size,
 561                                            &host->dma, GFP_KERNEL);
 562         if (host->buffer == NULL)
 563                 return -ENOMEM;
 564
 565         host->sdphy = devm_platform_ioremap_resource_byname(pdev, "phy");
 566         if (IS_ERR(host->sdphy))
 567                 return PTR_ERR(host->sdphy);
 568
 569         host->sdcore = devm_platform_ioremap_resource_byname(pdev, "core");
 570         if (IS_ERR(host->sdcore))
 571                 return PTR_ERR(host->sdcore);
 572
 573         host->sdreader = devm_platform_ioremap_resource_byname(pdev, "reader");
 574         if (IS_ERR(host->sdreader))
 575                 return PTR_ERR(host->sdreader);
 576
 577         host->sdwriter = devm_platform_ioremap_resource_byname(pdev, "writer");
 578         if (IS_ERR(host->sdwriter))
 579                 return PTR_ERR(host->sdwriter);
 580
 581         /* Ensure DMA bus masters are disabled */
 582         litex_write8(host->sdreader + LITEX_BLK2MEM_ENA, 0);
 583         litex_write8(host->sdwriter + LITEX_MEM2BLK_ENA, 0);
 584
 585         init_completion(&host->cmd_done);
 586         ret = litex_mmc_irq_init(pdev, host);
 587         if (ret)
 588                 return ret;
 589
 590         mmc->ops = &litex_mmc_ops;
 591
 592         ret = mmc_regulator_get_supply(mmc);
 593         if (ret || mmc->ocr_avail == 0) {
 594                 dev_warn(dev, "can't get voltage, defaulting to 3.3V\n");
 595                 mmc->ocr_avail = MMC_VDD_32_33 | MMC_VDD_33_34;
 596         }
 597
 598         /*
 599          * Set default sd_clk frequency range based on empirical observations
 600          * of LiteSDCard gateware behavior on typical SDCard media
 601          */
 602         mmc->f_min = 12.5e6;
 603         mmc->f_max = 50e6;
 604
 605         ret = mmc_of_parse(mmc);
 606         if (ret)
 607                 return ret;
 608
 609         /* Force 4-bit bus_width (only width supported by hardware) */
 610         mmc->caps &= ~MMC_CAP_8_BIT_DATA;
 611         mmc->caps |= MMC_CAP_4_BIT_DATA;
 612
 613         /* Set default capabilities */
 614         mmc->caps |= MMC_CAP_WAIT_WHILE_BUSY |
 615                      MMC_CAP_DRIVER_TYPE_D |
 616                      MMC_CAP_CMD23;
 617         mmc->caps2 |= MMC_CAP2_NO_WRITE_PROTECT |
 618                       MMC_CAP2_NO_SDIO |
 619                       MMC_CAP2_NO_MMC;
 620
 621         platform_set_drvdata(pdev, host);
 622
 623         ret = mmc_add_host(mmc);
 624         if (ret)
 625                 return ret;
 626
 627         dev_info(dev, "LiteX MMC controller initialized.\n");
 628         return 0;
 629 }
 630
 631 static int litex_mmc_remove(struct platform_device *pdev)
 632 {
 633         struct litex_mmc_host *host = platform_get_drvdata(pdev);
 634
 635         mmc_remove_host(host->mmc);
 636         return 0;
 637 }
 638
 639 static const struct of_device_id litex_match[] = {
 640         { .compatible = "litex,mmc" },
 641         { }
 642 };
 643 MODULE_DEVICE_TABLE(of, litex_match);
 644
 645 static struct platform_driver litex_mmc_driver = {
 646         .probe = litex_mmc_probe,
 647         .remove = litex_mmc_remove,
 648         .driver = {
 649                 .name = "litex-mmc",
 650                 .of_match_table = litex_match,
 651         },
 652 };
 653 module_platform_driver(litex_mmc_driver);
 654
 655 MODULE_DESCRIPTION("LiteX SDCard driver");
 656 MODULE_AUTHOR("Antmicro <contact@antmicro.com>");
 657 MODULE_AUTHOR("Kamil Rakoczy <krakoczy@antmicro.com>");
 658 MODULE_AUTHOR("Maciej Dudek <mdudek@internships.antmicro.com>");
 659 MODULE_AUTHOR("Paul Mackerras <paulus@ozlabs.org>");
 660 MODULE_AUTHOR("Gabriel Somlo <gsomlo@gmail.com>");
 661 MODULE_LICENSE("GPL v2");