drivers/fsi/fsi-master-aspeed.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 // Copyright (C) IBM Corporation 2018
   3 // FSI master driver for AST2600
   4
   5 #include <linux/clk.h>
   6 #include <linux/delay.h>
   7 #include <linux/fsi.h>
   8 #include <linux/io.h>
   9 #include <linux/mfd/syscon.h>
  10 #include <linux/module.h>
  11 #include <linux/mutex.h>
  12 #include <linux/of.h>
  13 #include <linux/platform_device.h>
  14 #include <linux/regmap.h>
  15 #include <linux/slab.h>
  16 #include <linux/iopoll.h>
  17 #include <linux/gpio/consumer.h>
  18
  19 #include "fsi-master.h"
  20
  21 struct fsi_master_aspeed {
  22         struct fsi_master       master;
  23         struct mutex            lock;   /* protect HW access */
  24         struct device           *dev;
  25         void __iomem            *base;
  26         struct clk              *clk;
  27         struct gpio_desc        *cfam_reset_gpio;
  28 };
  29
  30 #define to_fsi_master_aspeed(m) \
  31         container_of(m, struct fsi_master_aspeed, master)
  32
  33 /* Control register (size 0x400) */
  34 static const u32 ctrl_base = 0x80000000;
  35
  36 static const u32 fsi_base = 0xa0000000;
  37
  38 #define OPB_FSI_VER     0x00
  39 #define OPB_TRIGGER     0x04
  40 #define OPB_CTRL_BASE   0x08
  41 #define OPB_FSI_BASE    0x0c
  42 #define OPB_CLK_SYNC    0x3c
  43 #define OPB_IRQ_CLEAR   0x40
  44 #define OPB_IRQ_MASK    0x44
  45 #define OPB_IRQ_STATUS  0x48
  46
  47 #define OPB0_SELECT     0x10
  48 #define OPB0_RW         0x14
  49 #define OPB0_XFER_SIZE  0x18
  50 #define OPB0_FSI_ADDR   0x1c
  51 #define OPB0_FSI_DATA_W 0x20
  52 #define OPB0_STATUS     0x80
  53 #define OPB0_FSI_DATA_R 0x84
  54
  55 #define OPB0_WRITE_ORDER1       0x4c
  56 #define OPB0_WRITE_ORDER2       0x50
  57 #define OPB1_WRITE_ORDER1       0x54
  58 #define OPB1_WRITE_ORDER2       0x58
  59 #define OPB0_READ_ORDER1        0x5c
  60 #define OPB1_READ_ORDER2        0x60
  61
  62 #define OPB_RETRY_COUNTER       0x64
  63
  64 /* OPBn_STATUS */
  65 #define STATUS_HALFWORD_ACK     BIT(0)
  66 #define STATUS_FULLWORD_ACK     BIT(1)
  67 #define STATUS_ERR_ACK          BIT(2)
  68 #define STATUS_RETRY            BIT(3)
  69 #define STATUS_TIMEOUT          BIT(4)
  70
  71 /* OPB_IRQ_MASK */
  72 #define OPB1_XFER_ACK_EN BIT(17)
  73 #define OPB0_XFER_ACK_EN BIT(16)
  74
  75 /* OPB_RW */
  76 #define CMD_READ        BIT(0)
  77 #define CMD_WRITE       0
  78
  79 /* OPBx_XFER_SIZE */
  80 #define XFER_FULLWORD   (BIT(1) | BIT(0))
  81 #define XFER_HALFWORD   (BIT(0))
  82 #define XFER_BYTE       (0)
  83
  84 #define CREATE_TRACE_POINTS
  85 #include <trace/events/fsi_master_aspeed.h>
  86
  87 #define FSI_LINK_ENABLE_SETUP_TIME      10      /* in mS */
  88
  89 /* Run the bus at maximum speed by default */
  90 #define FSI_DIVISOR_DEFAULT            1
  91 #define FSI_DIVISOR_CABLED             2
  92 static u16 aspeed_fsi_divisor = FSI_DIVISOR_DEFAULT;
  93 module_param_named(bus_div,aspeed_fsi_divisor, ushort, 0);
  94
  95 #define OPB_POLL_TIMEOUT                500
  96
  97 static int __opb_write(struct fsi_master_aspeed *aspeed, u32 addr,
  98                        u32 val, u32 transfer_size)
  99 {
 100         void __iomem *base = aspeed->base;
 101         u32 reg, status;
 102         int ret;
 103
 104         /*
 105          * The ordering of these writes up until the trigger
 106          * write does not matter, so use writel_relaxed.
 107          */
 108         writel_relaxed(CMD_WRITE, base + OPB0_RW);
 109         writel_relaxed(transfer_size, base + OPB0_XFER_SIZE);
 110         writel_relaxed(addr, base + OPB0_FSI_ADDR);
 111         writel_relaxed(val, base + OPB0_FSI_DATA_W);
 112         writel_relaxed(0x1, base + OPB_IRQ_CLEAR);
 113         writel(0x1, base + OPB_TRIGGER);
 114
 115         ret = readl_poll_timeout(base + OPB_IRQ_STATUS, reg,
 116                                 (reg & OPB0_XFER_ACK_EN) != 0,
 117                                 0, OPB_POLL_TIMEOUT);
 118
 119         status = readl(base + OPB0_STATUS);
 120
 121         trace_fsi_master_aspeed_opb_write(addr, val, transfer_size, status, reg);
 122
 123         /* Return error when poll timed out */
 124         if (ret)
 125                 return ret;
 126
 127         /* Command failed, master will reset */
 128         if (status & STATUS_ERR_ACK)
 129                 return -EIO;
 130
 131         return 0;
 132 }
 133
 134 static int opb_writeb(struct fsi_master_aspeed *aspeed, u32 addr, u8 val)
 135 {
 136         return __opb_write(aspeed, addr, val, XFER_BYTE);
 137 }
 138
 139 static int opb_writew(struct fsi_master_aspeed *aspeed, u32 addr, __be16 val)
 140 {
 141         return __opb_write(aspeed, addr, (__force u16)val, XFER_HALFWORD);
 142 }
 143
 144 static int opb_writel(struct fsi_master_aspeed *aspeed, u32 addr, __be32 val)
 145 {
 146         return __opb_write(aspeed, addr, (__force u32)val, XFER_FULLWORD);
 147 }
 148
 149 static int __opb_read(struct fsi_master_aspeed *aspeed, uint32_t addr,
 150                       u32 transfer_size, void *out)
 151 {
 152         void __iomem *base = aspeed->base;
 153         u32 result, reg;
 154         int status, ret;
 155
 156         /*
 157          * The ordering of these writes up until the trigger
 158          * write does not matter, so use writel_relaxed.
 159          */
 160         writel_relaxed(CMD_READ, base + OPB0_RW);
 161         writel_relaxed(transfer_size, base + OPB0_XFER_SIZE);
 162         writel_relaxed(addr, base + OPB0_FSI_ADDR);
 163         writel_relaxed(0x1, base + OPB_IRQ_CLEAR);
 164         writel(0x1, base + OPB_TRIGGER);
 165
 166         ret = readl_poll_timeout(base + OPB_IRQ_STATUS, reg,
 167                            (reg & OPB0_XFER_ACK_EN) != 0,
 168                            0, OPB_POLL_TIMEOUT);
 169
 170         status = readl(base + OPB0_STATUS);
 171
 172         result = readl(base + OPB0_FSI_DATA_R);
 173
 174         trace_fsi_master_aspeed_opb_read(addr, transfer_size, result,
 175                         readl(base + OPB0_STATUS),
 176                         reg);
 177
 178         /* Return error when poll timed out */
 179         if (ret)
 180                 return ret;
 181
 182         /* Command failed, master will reset */
 183         if (status & STATUS_ERR_ACK)
 184                 return -EIO;
 185
 186         if (out) {
 187                 switch (transfer_size) {
 188                 case XFER_BYTE:
 189                         *(u8 *)out = result;
 190                         break;
 191                 case XFER_HALFWORD:
 192                         *(u16 *)out = result;
 193                         break;
 194                 case XFER_FULLWORD:
 195                         *(u32 *)out = result;
 196                         break;
 197                 default:
 198                         return -EINVAL;
 199                 }
 200
 201         }
 202
 203         return 0;
 204 }
 205
 206 static int opb_readl(struct fsi_master_aspeed *aspeed, uint32_t addr, __be32 *out)
 207 {
 208         return __opb_read(aspeed, addr, XFER_FULLWORD, out);
 209 }
 210
 211 static int opb_readw(struct fsi_master_aspeed *aspeed, uint32_t addr, __be16 *out)
 212 {
 213         return __opb_read(aspeed, addr, XFER_HALFWORD, (void *)out);
 214 }
 215
 216 static int opb_readb(struct fsi_master_aspeed *aspeed, uint32_t addr, u8 *out)
 217 {
 218         return __opb_read(aspeed, addr, XFER_BYTE, (void *)out);
 219 }
 220
 221 static int check_errors(struct fsi_master_aspeed *aspeed, int err)
 222 {
 223         int ret;
 224
 225         if (trace_fsi_master_aspeed_opb_error_enabled()) {
 226                 __be32 mresp0, mstap0, mesrb0;
 227
 228                 opb_readl(aspeed, ctrl_base + FSI_MRESP0, &mresp0);
 229                 opb_readl(aspeed, ctrl_base + FSI_MSTAP0, &mstap0);
 230                 opb_readl(aspeed, ctrl_base + FSI_MESRB0, &mesrb0);
 231
 232                 trace_fsi_master_aspeed_opb_error(
 233                                 be32_to_cpu(mresp0),
 234                                 be32_to_cpu(mstap0),
 235                                 be32_to_cpu(mesrb0));
 236         }
 237
 238         if (err == -EIO) {
 239                 /* Check MAEB (0x70) ? */
 240
 241                 /* Then clear errors in master */
 242                 ret = opb_writel(aspeed, ctrl_base + FSI_MRESP0,
 243                                 cpu_to_be32(FSI_MRESP_RST_ALL_MASTER));
 244                 if (ret) {
 245                         /* TODO: log? return different code? */
 246                         return ret;
 247                 }
 248                 /* TODO: confirm that 0x70 was okay */
 249         }
 250
 251         /* This will pass through timeout errors */
 252         return err;
 253 }
 254
 255 static int aspeed_master_read(struct fsi_master *master, int link,
 256                         uint8_t id, uint32_t addr, void *val, size_t size)
 257 {
 258         struct fsi_master_aspeed *aspeed = to_fsi_master_aspeed(master);
 259         int ret;
 260
 261         if (id > 0x3)
 262                 return -EINVAL;
 263
 264         addr |= id << 21;
 265         addr += link * FSI_HUB_LINK_SIZE;
 266
 267         mutex_lock(&aspeed->lock);
 268
 269         switch (size) {
 270         case 1:
 271                 ret = opb_readb(aspeed, fsi_base + addr, val);
 272                 break;
 273         case 2:
 274                 ret = opb_readw(aspeed, fsi_base + addr, val);
 275                 break;
 276         case 4:
 277                 ret = opb_readl(aspeed, fsi_base + addr, val);
 278                 break;
 279         default:
 280                 ret = -EINVAL;
 281                 goto done;
 282         }
 283
 284         ret = check_errors(aspeed, ret);
 285 done:
 286         mutex_unlock(&aspeed->lock);
 287         return ret;
 288 }
 289
 290 static int aspeed_master_write(struct fsi_master *master, int link,
 291                         uint8_t id, uint32_t addr, const void *val, size_t size)
 292 {
 293         struct fsi_master_aspeed *aspeed = to_fsi_master_aspeed(master);
 294         int ret;
 295
 296         if (id > 0x3)
 297                 return -EINVAL;
 298
 299         addr |= id << 21;
 300         addr += link * FSI_HUB_LINK_SIZE;
 301
 302         mutex_lock(&aspeed->lock);
 303
 304         switch (size) {
 305         case 1:
 306                 ret = opb_writeb(aspeed, fsi_base + addr, *(u8 *)val);
 307                 break;
 308         case 2:
 309                 ret = opb_writew(aspeed, fsi_base + addr, *(__be16 *)val);
 310                 break;
 311         case 4:
 312                 ret = opb_writel(aspeed, fsi_base + addr, *(__be32 *)val);
 313                 break;
 314         default:
 315                 ret = -EINVAL;
 316                 goto done;
 317         }
 318
 319         ret = check_errors(aspeed, ret);
 320 done:
 321         mutex_unlock(&aspeed->lock);
 322         return ret;
 323 }
 324
 325 static int aspeed_master_link_enable(struct fsi_master *master, int link,
 326                                      bool enable)
 327 {
 328         struct fsi_master_aspeed *aspeed = to_fsi_master_aspeed(master);
 329         int idx, bit, ret;
 330         __be32 reg;
 331
 332         idx = link / 32;
 333         bit = link % 32;
 334
 335         reg = cpu_to_be32(0x80000000 >> bit);
 336
 337         mutex_lock(&aspeed->lock);
 338
 339         if (!enable) {
 340                 ret = opb_writel(aspeed, ctrl_base + FSI_MCENP0 + (4 * idx), reg);
 341                 goto done;
 342         }
 343
 344         ret = opb_writel(aspeed, ctrl_base + FSI_MSENP0 + (4 * idx), reg);
 345         if (ret)
 346                 goto done;
 347
 348         mdelay(FSI_LINK_ENABLE_SETUP_TIME);
 349 done:
 350         mutex_unlock(&aspeed->lock);
 351         return ret;
 352 }
 353
 354 static int aspeed_master_term(struct fsi_master *master, int link, uint8_t id)
 355 {
 356         uint32_t addr;
 357         __be32 cmd;
 358
 359         addr = 0x4;
 360         cmd = cpu_to_be32(0xecc00000);
 361
 362         return aspeed_master_write(master, link, id, addr, &cmd, 4);
 363 }
 364
 365 static int aspeed_master_break(struct fsi_master *master, int link)
 366 {
 367         uint32_t addr;
 368         __be32 cmd;
 369
 370         addr = 0x0;
 371         cmd = cpu_to_be32(0xc0de0000);
 372
 373         return aspeed_master_write(master, link, 0, addr, &cmd, 4);
 374 }
 375
 376 static void aspeed_master_release(struct device *dev)
 377 {
 378         struct fsi_master_aspeed *aspeed =
 379                 to_fsi_master_aspeed(dev_to_fsi_master(dev));
 380
 381         kfree(aspeed);
 382 }
 383
 384 /* mmode encoders */
 385 static inline u32 fsi_mmode_crs0(u32 x)
 386 {
 387         return (x & FSI_MMODE_CRS0MASK) << FSI_MMODE_CRS0SHFT;
 388 }
 389
 390 static inline u32 fsi_mmode_crs1(u32 x)
 391 {
 392         return (x & FSI_MMODE_CRS1MASK) << FSI_MMODE_CRS1SHFT;
 393 }
 394
 395 static int aspeed_master_init(struct fsi_master_aspeed *aspeed)
 396 {
 397         __be32 reg;
 398
 399         reg = cpu_to_be32(FSI_MRESP_RST_ALL_MASTER | FSI_MRESP_RST_ALL_LINK
 400                         | FSI_MRESP_RST_MCR | FSI_MRESP_RST_PYE);
 401         opb_writel(aspeed, ctrl_base + FSI_MRESP0, reg);
 402
 403         /* Initialize the MFSI (hub master) engine */
 404         reg = cpu_to_be32(FSI_MRESP_RST_ALL_MASTER | FSI_MRESP_RST_ALL_LINK
 405                         | FSI_MRESP_RST_MCR | FSI_MRESP_RST_PYE);
 406         opb_writel(aspeed, ctrl_base + FSI_MRESP0, reg);
 407
 408         reg = cpu_to_be32(FSI_MECTRL_EOAE | FSI_MECTRL_P8_AUTO_TERM);
 409         opb_writel(aspeed, ctrl_base + FSI_MECTRL, reg);
 410
 411         reg = cpu_to_be32(FSI_MMODE_ECRC | FSI_MMODE_EPC | FSI_MMODE_RELA
 412                         | fsi_mmode_crs0(aspeed_fsi_divisor)
 413                         | fsi_mmode_crs1(aspeed_fsi_divisor)
 414                         | FSI_MMODE_P8_TO_LSB);
 415         dev_info(aspeed->dev, "mmode set to %08x (divisor %d)\n",
 416                         be32_to_cpu(reg), aspeed_fsi_divisor);
 417         opb_writel(aspeed, ctrl_base + FSI_MMODE, reg);
 418
 419         reg = cpu_to_be32(0xffff0000);
 420         opb_writel(aspeed, ctrl_base + FSI_MDLYR, reg);
 421
 422         reg = cpu_to_be32(~0);
 423         opb_writel(aspeed, ctrl_base + FSI_MSENP0, reg);
 424
 425         /* Leave enabled long enough for master logic to set up */
 426         mdelay(FSI_LINK_ENABLE_SETUP_TIME);
 427
 428         opb_writel(aspeed, ctrl_base + FSI_MCENP0, reg);
 429
 430         opb_readl(aspeed, ctrl_base + FSI_MAEB, NULL);
 431
 432         reg = cpu_to_be32(FSI_MRESP_RST_ALL_MASTER | FSI_MRESP_RST_ALL_LINK);
 433         opb_writel(aspeed, ctrl_base + FSI_MRESP0, reg);
 434
 435         opb_readl(aspeed, ctrl_base + FSI_MLEVP0, NULL);
 436
 437         /* Reset the master bridge */
 438         reg = cpu_to_be32(FSI_MRESB_RST_GEN);
 439         opb_writel(aspeed, ctrl_base + FSI_MRESB0, reg);
 440
 441         reg = cpu_to_be32(FSI_MRESB_RST_ERR);
 442         opb_writel(aspeed, ctrl_base + FSI_MRESB0, reg);
 443
 444         return 0;
 445 }
 446
 447 static ssize_t cfam_reset_store(struct device *dev, struct device_attribute *attr,
 448                                 const char *buf, size_t count)
 449 {
 450         struct fsi_master_aspeed *aspeed = dev_get_drvdata(dev);
 451
 452         mutex_lock(&aspeed->lock);
 453         gpiod_set_value(aspeed->cfam_reset_gpio, 1);
 454         usleep_range(900, 1000);
 455         gpiod_set_value(aspeed->cfam_reset_gpio, 0);
 456         mutex_unlock(&aspeed->lock);
 457
 458         return count;
 459 }
 460
 461 static DEVICE_ATTR(cfam_reset, 0200, NULL, cfam_reset_store);
 462
 463 static int setup_cfam_reset(struct fsi_master_aspeed *aspeed)
 464 {
 465         struct device *dev = aspeed->dev;
 466         struct gpio_desc *gpio;
 467         int rc;
 468
 469         gpio = devm_gpiod_get_optional(dev, "cfam-reset", GPIOD_OUT_LOW);
 470         if (IS_ERR(gpio))
 471                 return PTR_ERR(gpio);
 472         if (!gpio)
 473                 return 0;
 474
 475         aspeed->cfam_reset_gpio = gpio;
 476
 477         rc = device_create_file(dev, &dev_attr_cfam_reset);
 478         if (rc) {
 479                 devm_gpiod_put(dev, gpio);
 480                 return rc;
 481         }
 482
 483         return 0;
 484 }
 485
 486 static int tacoma_cabled_fsi_fixup(struct device *dev)
 487 {
 488         struct gpio_desc *routing_gpio, *mux_gpio;
 489         int gpio;
 490
 491         /*
 492          * The routing GPIO is a jumper indicating we should mux for the
 493          * externally connected FSI cable.
 494          */
 495         routing_gpio = devm_gpiod_get_optional(dev, "fsi-routing",
 496                         GPIOD_IN | GPIOD_FLAGS_BIT_NONEXCLUSIVE);
 497         if (IS_ERR(routing_gpio))
 498                 return PTR_ERR(routing_gpio);
 499         if (!routing_gpio)
 500                 return 0;
 501
 502         mux_gpio = devm_gpiod_get_optional(dev, "fsi-mux", GPIOD_ASIS);
 503         if (IS_ERR(mux_gpio))
 504                 return PTR_ERR(mux_gpio);
 505         if (!mux_gpio)
 506                 return 0;
 507
 508         gpio = gpiod_get_value(routing_gpio);
 509         if (gpio < 0)
 510                 return gpio;
 511
 512         /* If the routing GPIO is high we should set the mux to low. */
 513         if (gpio) {
 514                 /*
 515                  * Cable signal integrity means we should run the bus
 516                  * slightly slower. Do not override if a kernel param
 517                  * has already overridden.
 518                  */
 519                 if (aspeed_fsi_divisor == FSI_DIVISOR_DEFAULT)
 520                         aspeed_fsi_divisor = FSI_DIVISOR_CABLED;
 521
 522                 gpiod_direction_output(mux_gpio, 0);
 523                 dev_info(dev, "FSI configured for external cable\n");
 524         } else {
 525                 gpiod_direction_output(mux_gpio, 1);
 526         }
 527
 528         devm_gpiod_put(dev, routing_gpio);
 529
 530         return 0;
 531 }
 532
 533 static int fsi_master_aspeed_probe(struct platform_device *pdev)
 534 {
 535         struct fsi_master_aspeed *aspeed;
 536         int rc, links, reg;
 537         __be32 raw;
 538
 539         rc = tacoma_cabled_fsi_fixup(&pdev->dev);
 540         if (rc) {
 541                 dev_err(&pdev->dev, "Tacoma FSI cable fixup failed\n");
 542                 return rc;
 543         }
 544
 545         aspeed = devm_kzalloc(&pdev->dev, sizeof(*aspeed), GFP_KERNEL);
 546         if (!aspeed)
 547                 return -ENOMEM;
 548
 549         aspeed->dev = &pdev->dev;
 550
 551         aspeed->base = devm_platform_ioremap_resource(pdev, 0);
 552         if (IS_ERR(aspeed->base))
 553                 return PTR_ERR(aspeed->base);
 554
 555         aspeed->clk = devm_clk_get(aspeed->dev, NULL);
 556         if (IS_ERR(aspeed->clk)) {
 557                 dev_err(aspeed->dev, "couldn't get clock\n");
 558                 return PTR_ERR(aspeed->clk);
 559         }
 560         rc = clk_prepare_enable(aspeed->clk);
 561         if (rc) {
 562                 dev_err(aspeed->dev, "couldn't enable clock\n");
 563                 return rc;
 564         }
 565
 566         rc = setup_cfam_reset(aspeed);
 567         if (rc) {
 568                 dev_err(&pdev->dev, "CFAM reset GPIO setup failed\n");
 569         }
 570
 571         writel(0x1, aspeed->base + OPB_CLK_SYNC);
 572         writel(OPB1_XFER_ACK_EN | OPB0_XFER_ACK_EN,
 573                         aspeed->base + OPB_IRQ_MASK);
 574
 575         /* TODO: determine an appropriate value */
 576         writel(0x10, aspeed->base + OPB_RETRY_COUNTER);
 577
 578         writel(ctrl_base, aspeed->base + OPB_CTRL_BASE);
 579         writel(fsi_base, aspeed->base + OPB_FSI_BASE);
 580
 581         /* Set read data order */
 582         writel(0x00030b1b, aspeed->base + OPB0_READ_ORDER1);
 583
 584         /* Set write data order */
 585         writel(0x0011101b, aspeed->base + OPB0_WRITE_ORDER1);
 586         writel(0x0c330f3f, aspeed->base + OPB0_WRITE_ORDER2);
 587
 588         /*
 589          * Select OPB0 for all operations.
 590          * Will need to be reworked when enabling DMA or anything that uses
 591          * OPB1.
 592          */
 593         writel(0x1, aspeed->base + OPB0_SELECT);
 594
 595         rc = opb_readl(aspeed, ctrl_base + FSI_MVER, &raw);
 596         if (rc) {
 597                 dev_err(&pdev->dev, "failed to read hub version\n");
 598                 return rc;
 599         }
 600
 601         reg = be32_to_cpu(raw);
 602         links = (reg >> 8) & 0xff;
 603         dev_info(&pdev->dev, "hub version %08x (%d links)\n", reg, links);
 604
 605         aspeed->master.dev.parent = &pdev->dev;
 606         aspeed->master.dev.release = aspeed_master_release;
 607         aspeed->master.dev.of_node = of_node_get(dev_of_node(&pdev->dev));
 608
 609         aspeed->master.n_links = links;
 610         aspeed->master.read = aspeed_master_read;
 611         aspeed->master.write = aspeed_master_write;
 612         aspeed->master.send_break = aspeed_master_break;
 613         aspeed->master.term = aspeed_master_term;
 614         aspeed->master.link_enable = aspeed_master_link_enable;
 615
 616         dev_set_drvdata(&pdev->dev, aspeed);
 617
 618         mutex_init(&aspeed->lock);
 619         aspeed_master_init(aspeed);
 620
 621         rc = fsi_master_register(&aspeed->master);
 622         if (rc)
 623                 goto err_release;
 624
 625         /* At this point, fsi_master_register performs the device_initialize(),
 626          * and holds the sole reference on master.dev. This means the device
 627          * will be freed (via ->release) during any subsequent call to
 628          * fsi_master_unregister.  We add our own reference to it here, so we
 629          * can perform cleanup (in _remove()) without it being freed before
 630          * we're ready.
 631          */
 632         get_device(&aspeed->master.dev);
 633         return 0;
 634
 635 err_release:
 636         clk_disable_unprepare(aspeed->clk);
 637         return rc;
 638 }
 639
 640 static int fsi_master_aspeed_remove(struct platform_device *pdev)
 641 {
 642         struct fsi_master_aspeed *aspeed = platform_get_drvdata(pdev);
 643
 644         fsi_master_unregister(&aspeed->master);
 645         clk_disable_unprepare(aspeed->clk);
 646
 647         return 0;
 648 }
 649
 650 static const struct of_device_id fsi_master_aspeed_match[] = {
 651         { .compatible = "aspeed,ast2600-fsi-master" },
 652         { },
 653 };
 654 MODULE_DEVICE_TABLE(of, fsi_master_aspeed_match);
 655
 656 static struct platform_driver fsi_master_aspeed_driver = {
 657         .driver = {
 658                 .name           = "fsi-master-aspeed",
 659                 .of_match_table = fsi_master_aspeed_match,
 660         },
 661         .probe  = fsi_master_aspeed_probe,
 662         .remove = fsi_master_aspeed_remove,
 663 };
 664
 665 module_platform_driver(fsi_master_aspeed_driver);
 666 MODULE_LICENSE("GPL");