drivers/bus/sunxi-rsb.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * RSB (Reduced Serial Bus) driver.
   4  *
   5  * Author: Chen-Yu Tsai <wens@csie.org>
   6  *
   7  * The RSB controller looks like an SMBus controller which only supports
   8  * byte and word data transfers. But, it differs from standard SMBus
   9  * protocol on several aspects:
  10  * - it uses addresses set at runtime to address slaves. Runtime addresses
  11  *   are sent to slaves using their 12bit hardware addresses. Up to 15
  12  *   runtime addresses are available.
  13  * - it adds a parity bit every 8bits of data and address for read and
  14  *   write accesses; this replaces the ack bit
  15  * - only one read access is required to read a byte (instead of a write
  16  *   followed by a read access in standard SMBus protocol)
  17  * - there's no Ack bit after each read access
  18  *
  19  * This means this bus cannot be used to interface with standard SMBus
  20  * devices. Devices known to support this interface include the AXP223,
  21  * AXP809, and AXP806 PMICs, and the AC100 audio codec, all from X-Powers.
  22  *
  23  * A description of the operation and wire protocol can be found in the
  24  * RSB section of Allwinner's A80 user manual, which can be found at
  25  *
  26  *     https://github.com/allwinner-zh/documents/tree/master/A80
  27  *
  28  * This document is officially released by Allwinner.
  29  *
  30  * This driver is based on i2c-sun6i-p2wi.c, the P2WI bus driver.
  31  */
  32
  33 #include <linux/clk.h>
  34 #include <linux/clk/clk-conf.h>
  35 #include <linux/device.h>
  36 #include <linux/interrupt.h>
  37 #include <linux/io.h>
  38 #include <linux/iopoll.h>
  39 #include <linux/module.h>
  40 #include <linux/of.h>
  41 #include <linux/of_irq.h>
  42 #include <linux/of_platform.h>
  43 #include <linux/platform_device.h>
  44 #include <linux/pm.h>
  45 #include <linux/pm_runtime.h>
  46 #include <linux/regmap.h>
  47 #include <linux/reset.h>
  48 #include <linux/slab.h>
  49 #include <linux/sunxi-rsb.h>
  50 #include <linux/types.h>
  51
  52 /* RSB registers */
  53 #define RSB_CTRL        0x0     /* Global control */
  54 #define RSB_CCR         0x4     /* Clock control */
  55 #define RSB_INTE        0x8     /* Interrupt controls */
  56 #define RSB_INTS        0xc     /* Interrupt status */
  57 #define RSB_ADDR        0x10    /* Address to send with read/write command */
  58 #define RSB_DATA        0x1c    /* Data to read/write */
  59 #define RSB_LCR         0x24    /* Line control */
  60 #define RSB_DMCR        0x28    /* Device mode (init) control */
  61 #define RSB_CMD         0x2c    /* RSB Command */
  62 #define RSB_DAR         0x30    /* Device address / runtime address */
  63
  64 /* CTRL fields */
  65 #define RSB_CTRL_START_TRANS            BIT(7)
  66 #define RSB_CTRL_ABORT_TRANS            BIT(6)
  67 #define RSB_CTRL_GLOBAL_INT_ENB         BIT(1)
  68 #define RSB_CTRL_SOFT_RST               BIT(0)
  69
  70 /* CLK CTRL fields */
  71 #define RSB_CCR_SDA_OUT_DELAY(v)        (((v) & 0x7) << 8)
  72 #define RSB_CCR_MAX_CLK_DIV             0xff
  73 #define RSB_CCR_CLK_DIV(v)              ((v) & RSB_CCR_MAX_CLK_DIV)
  74
  75 /* STATUS fields */
  76 #define RSB_INTS_TRANS_ERR_ACK          BIT(16)
  77 #define RSB_INTS_TRANS_ERR_DATA_BIT(v)  (((v) >> 8) & 0xf)
  78 #define RSB_INTS_TRANS_ERR_DATA         GENMASK(11, 8)
  79 #define RSB_INTS_LOAD_BSY               BIT(2)
  80 #define RSB_INTS_TRANS_ERR              BIT(1)
  81 #define RSB_INTS_TRANS_OVER             BIT(0)
  82
  83 /* LINE CTRL fields*/
  84 #define RSB_LCR_SCL_STATE               BIT(5)
  85 #define RSB_LCR_SDA_STATE               BIT(4)
  86 #define RSB_LCR_SCL_CTL                 BIT(3)
  87 #define RSB_LCR_SCL_CTL_EN              BIT(2)
  88 #define RSB_LCR_SDA_CTL                 BIT(1)
  89 #define RSB_LCR_SDA_CTL_EN              BIT(0)
  90
  91 /* DEVICE MODE CTRL field values */
  92 #define RSB_DMCR_DEVICE_START           BIT(31)
  93 #define RSB_DMCR_MODE_DATA              (0x7c << 16)
  94 #define RSB_DMCR_MODE_REG               (0x3e << 8)
  95 #define RSB_DMCR_DEV_ADDR               0x00
  96
  97 /* CMD values */
  98 #define RSB_CMD_RD8                     0x8b
  99 #define RSB_CMD_RD16                    0x9c
 100 #define RSB_CMD_RD32                    0xa6
 101 #define RSB_CMD_WR8                     0x4e
 102 #define RSB_CMD_WR16                    0x59
 103 #define RSB_CMD_WR32                    0x63
 104 #define RSB_CMD_STRA                    0xe8
 105
 106 /* DAR fields */
 107 #define RSB_DAR_RTA(v)                  (((v) & 0xff) << 16)
 108 #define RSB_DAR_DA(v)                   ((v) & 0xffff)
 109
 110 #define RSB_MAX_FREQ                    20000000
 111
 112 #define RSB_CTRL_NAME                   "sunxi-rsb"
 113
 114 struct sunxi_rsb_addr_map {
 115         u16 hwaddr;
 116         u8 rtaddr;
 117 };
 118
 119 struct sunxi_rsb {
 120         struct device *dev;
 121         void __iomem *regs;
 122         struct clk *clk;
 123         struct reset_control *rstc;
 124         struct completion complete;
 125         struct mutex lock;
 126         unsigned int status;
 127         u32 clk_freq;
 128 };
 129
 130 /* bus / slave device related functions */
 131 static struct bus_type sunxi_rsb_bus;
 132
 133 static int sunxi_rsb_device_match(struct device *dev, struct device_driver *drv)
 134 {
 135         return of_driver_match_device(dev, drv);
 136 }
 137
 138 static int sunxi_rsb_device_probe(struct device *dev)
 139 {
 140         const struct sunxi_rsb_driver *drv = to_sunxi_rsb_driver(dev->driver);
 141         struct sunxi_rsb_device *rdev = to_sunxi_rsb_device(dev);
 142         int ret;
 143
 144         if (!drv->probe)
 145                 return -ENODEV;
 146
 147         if (!rdev->irq) {
 148                 int irq = -ENOENT;
 149
 150                 if (dev->of_node)
 151                         irq = of_irq_get(dev->of_node, 0);
 152
 153                 if (irq == -EPROBE_DEFER)
 154                         return irq;
 155                 if (irq < 0)
 156                         irq = 0;
 157
 158                 rdev->irq = irq;
 159         }
 160
 161         ret = of_clk_set_defaults(dev->of_node, false);
 162         if (ret < 0)
 163                 return ret;
 164
 165         return drv->probe(rdev);
 166 }
 167
 168 static void sunxi_rsb_device_remove(struct device *dev)
 169 {
 170         const struct sunxi_rsb_driver *drv = to_sunxi_rsb_driver(dev->driver);
 171
 172         drv->remove(to_sunxi_rsb_device(dev));
 173 }
 174
 175 static struct bus_type sunxi_rsb_bus = {
 176         .name           = RSB_CTRL_NAME,
 177         .match          = sunxi_rsb_device_match,
 178         .probe          = sunxi_rsb_device_probe,
 179         .remove         = sunxi_rsb_device_remove,
 180         .uevent         = of_device_uevent_modalias,
 181 };
 182
 183 static void sunxi_rsb_dev_release(struct device *dev)
 184 {
 185         struct sunxi_rsb_device *rdev = to_sunxi_rsb_device(dev);
 186
 187         kfree(rdev);
 188 }
 189
 190 /**
 191  * sunxi_rsb_device_create() - allocate and add an RSB device
 192  * @rsb:        RSB controller
 193  * @node:       RSB slave device node
 194  * @hwaddr:     RSB slave hardware address
 195  * @rtaddr:     RSB slave runtime address
 196  */
 197 static struct sunxi_rsb_device *sunxi_rsb_device_create(struct sunxi_rsb *rsb,
 198                 struct device_node *node, u16 hwaddr, u8 rtaddr)
 199 {
 200         int err;
 201         struct sunxi_rsb_device *rdev;
 202
 203         rdev = kzalloc(sizeof(*rdev), GFP_KERNEL);
 204         if (!rdev)
 205                 return ERR_PTR(-ENOMEM);
 206
 207         rdev->rsb = rsb;
 208         rdev->hwaddr = hwaddr;
 209         rdev->rtaddr = rtaddr;
 210         rdev->dev.bus = &sunxi_rsb_bus;
 211         rdev->dev.parent = rsb->dev;
 212         rdev->dev.of_node = node;
 213         rdev->dev.release = sunxi_rsb_dev_release;
 214
 215         dev_set_name(&rdev->dev, "%s-%x", RSB_CTRL_NAME, hwaddr);
 216
 217         err = device_register(&rdev->dev);
 218         if (err < 0) {
 219                 dev_err(&rdev->dev, "Can't add %s, status %d\n",
 220                         dev_name(&rdev->dev), err);
 221                 goto err_device_add;
 222         }
 223
 224         dev_dbg(&rdev->dev, "device %s registered\n", dev_name(&rdev->dev));
 225
 226         return rdev;
 227
 228 err_device_add:
 229         put_device(&rdev->dev);
 230
 231         return ERR_PTR(err);
 232 }
 233
 234 /**
 235  * sunxi_rsb_device_unregister(): unregister an RSB device
 236  * @rdev:       rsb_device to be removed
 237  */
 238 static void sunxi_rsb_device_unregister(struct sunxi_rsb_device *rdev)
 239 {
 240         device_unregister(&rdev->dev);
 241 }
 242
 243 static int sunxi_rsb_remove_devices(struct device *dev, void *data)
 244 {
 245         struct sunxi_rsb_device *rdev = to_sunxi_rsb_device(dev);
 246
 247         if (dev->bus == &sunxi_rsb_bus)
 248                 sunxi_rsb_device_unregister(rdev);
 249
 250         return 0;
 251 }
 252
 253 /**
 254  * sunxi_rsb_driver_register() - Register device driver with RSB core
 255  * @rdrv:       device driver to be associated with slave-device.
 256  *
 257  * This API will register the client driver with the RSB framework.
 258  * It is typically called from the driver's module-init function.
 259  */
 260 int sunxi_rsb_driver_register(struct sunxi_rsb_driver *rdrv)
 261 {
 262         rdrv->driver.bus = &sunxi_rsb_bus;
 263         return driver_register(&rdrv->driver);
 264 }
 265 EXPORT_SYMBOL_GPL(sunxi_rsb_driver_register);
 266
 267 /* common code that starts a transfer */
 268 static int _sunxi_rsb_run_xfer(struct sunxi_rsb *rsb)
 269 {
 270         if (readl(rsb->regs + RSB_CTRL) & RSB_CTRL_START_TRANS) {
 271                 dev_dbg(rsb->dev, "RSB transfer still in progress\n");
 272                 return -EBUSY;
 273         }
 274
 275         reinit_completion(&rsb->complete);
 276
 277         writel(RSB_INTS_LOAD_BSY | RSB_INTS_TRANS_ERR | RSB_INTS_TRANS_OVER,
 278                rsb->regs + RSB_INTE);
 279         writel(RSB_CTRL_START_TRANS | RSB_CTRL_GLOBAL_INT_ENB,
 280                rsb->regs + RSB_CTRL);
 281
 282         if (!wait_for_completion_io_timeout(&rsb->complete,
 283                                             msecs_to_jiffies(100))) {
 284                 dev_dbg(rsb->dev, "RSB timeout\n");
 285
 286                 /* abort the transfer */
 287                 writel(RSB_CTRL_ABORT_TRANS, rsb->regs + RSB_CTRL);
 288
 289                 /* clear any interrupt flags */
 290                 writel(readl(rsb->regs + RSB_INTS), rsb->regs + RSB_INTS);
 291
 292                 return -ETIMEDOUT;
 293         }
 294
 295         if (rsb->status & RSB_INTS_LOAD_BSY) {
 296                 dev_dbg(rsb->dev, "RSB busy\n");
 297                 return -EBUSY;
 298         }
 299
 300         if (rsb->status & RSB_INTS_TRANS_ERR) {
 301                 if (rsb->status & RSB_INTS_TRANS_ERR_ACK) {
 302                         dev_dbg(rsb->dev, "RSB slave nack\n");
 303                         return -EINVAL;
 304                 }
 305
 306                 if (rsb->status & RSB_INTS_TRANS_ERR_DATA) {
 307                         dev_dbg(rsb->dev, "RSB transfer data error\n");
 308                         return -EIO;
 309                 }
 310         }
 311
 312         return 0;
 313 }
 314
 315 static int sunxi_rsb_read(struct sunxi_rsb *rsb, u8 rtaddr, u8 addr,
 316                           u32 *buf, size_t len)
 317 {
 318         u32 cmd;
 319         int ret;
 320
 321         if (!buf)
 322                 return -EINVAL;
 323
 324         switch (len) {
 325         case 1:
 326                 cmd = RSB_CMD_RD8;
 327                 break;
 328         case 2:
 329                 cmd = RSB_CMD_RD16;
 330                 break;
 331         case 4:
 332                 cmd = RSB_CMD_RD32;
 333                 break;
 334         default:
 335                 dev_err(rsb->dev, "Invalid access width: %zd\n", len);
 336                 return -EINVAL;
 337         }
 338
 339         ret = pm_runtime_resume_and_get(rsb->dev);
 340         if (ret)
 341                 return ret;
 342
 343         mutex_lock(&rsb->lock);
 344
 345         writel(addr, rsb->regs + RSB_ADDR);
 346         writel(RSB_DAR_RTA(rtaddr), rsb->regs + RSB_DAR);
 347         writel(cmd, rsb->regs + RSB_CMD);
 348
 349         ret = _sunxi_rsb_run_xfer(rsb);
 350         if (ret)
 351                 goto unlock;
 352
 353         *buf = readl(rsb->regs + RSB_DATA) & GENMASK(len * 8 - 1, 0);
 354
 355 unlock:
 356         mutex_unlock(&rsb->lock);
 357
 358         pm_runtime_mark_last_busy(rsb->dev);
 359         pm_runtime_put_autosuspend(rsb->dev);
 360
 361         return ret;
 362 }
 363
 364 static int sunxi_rsb_write(struct sunxi_rsb *rsb, u8 rtaddr, u8 addr,
 365                            const u32 *buf, size_t len)
 366 {
 367         u32 cmd;
 368         int ret;
 369
 370         if (!buf)
 371                 return -EINVAL;
 372
 373         switch (len) {
 374         case 1:
 375                 cmd = RSB_CMD_WR8;
 376                 break;
 377         case 2:
 378                 cmd = RSB_CMD_WR16;
 379                 break;
 380         case 4:
 381                 cmd = RSB_CMD_WR32;
 382                 break;
 383         default:
 384                 dev_err(rsb->dev, "Invalid access width: %zd\n", len);
 385                 return -EINVAL;
 386         }
 387
 388         ret = pm_runtime_resume_and_get(rsb->dev);
 389         if (ret)
 390                 return ret;
 391
 392         mutex_lock(&rsb->lock);
 393
 394         writel(addr, rsb->regs + RSB_ADDR);
 395         writel(RSB_DAR_RTA(rtaddr), rsb->regs + RSB_DAR);
 396         writel(*buf, rsb->regs + RSB_DATA);
 397         writel(cmd, rsb->regs + RSB_CMD);
 398         ret = _sunxi_rsb_run_xfer(rsb);
 399
 400         mutex_unlock(&rsb->lock);
 401
 402         pm_runtime_mark_last_busy(rsb->dev);
 403         pm_runtime_put_autosuspend(rsb->dev);
 404
 405         return ret;
 406 }
 407
 408 /* RSB regmap functions */
 409 struct sunxi_rsb_ctx {
 410         struct sunxi_rsb_device *rdev;
 411         int size;
 412 };
 413
 414 static int regmap_sunxi_rsb_reg_read(void *context, unsigned int reg,
 415                                      unsigned int *val)
 416 {
 417         struct sunxi_rsb_ctx *ctx = context;
 418         struct sunxi_rsb_device *rdev = ctx->rdev;
 419
 420         if (reg > 0xff)
 421                 return -EINVAL;
 422
 423         return sunxi_rsb_read(rdev->rsb, rdev->rtaddr, reg, val, ctx->size);
 424 }
 425
 426 static int regmap_sunxi_rsb_reg_write(void *context, unsigned int reg,
 427                                       unsigned int val)
 428 {
 429         struct sunxi_rsb_ctx *ctx = context;
 430         struct sunxi_rsb_device *rdev = ctx->rdev;
 431
 432         return sunxi_rsb_write(rdev->rsb, rdev->rtaddr, reg, &val, ctx->size);
 433 }
 434
 435 static void regmap_sunxi_rsb_free_ctx(void *context)
 436 {
 437         struct sunxi_rsb_ctx *ctx = context;
 438
 439         kfree(ctx);
 440 }
 441
 442 static struct regmap_bus regmap_sunxi_rsb = {
 443         .reg_write = regmap_sunxi_rsb_reg_write,
 444         .reg_read = regmap_sunxi_rsb_reg_read,
 445         .free_context = regmap_sunxi_rsb_free_ctx,
 446         .reg_format_endian_default = REGMAP_ENDIAN_NATIVE,
 447         .val_format_endian_default = REGMAP_ENDIAN_NATIVE,
 448 };
 449
 450 static struct sunxi_rsb_ctx *regmap_sunxi_rsb_init_ctx(struct sunxi_rsb_device *rdev,
 451                 const struct regmap_config *config)
 452 {
 453         struct sunxi_rsb_ctx *ctx;
 454
 455         switch (config->val_bits) {
 456         case 8:
 457         case 16:
 458         case 32:
 459                 break;
 460         default:
 461                 return ERR_PTR(-EINVAL);
 462         }
 463
 464         ctx = kzalloc(sizeof(*ctx), GFP_KERNEL);
 465         if (!ctx)
 466                 return ERR_PTR(-ENOMEM);
 467
 468         ctx->rdev = rdev;
 469         ctx->size = config->val_bits / 8;
 470
 471         return ctx;
 472 }
 473
 474 struct regmap *__devm_regmap_init_sunxi_rsb(struct sunxi_rsb_device *rdev,
 475                                             const struct regmap_config *config,
 476                                             struct lock_class_key *lock_key,
 477                                             const char *lock_name)
 478 {
 479         struct sunxi_rsb_ctx *ctx = regmap_sunxi_rsb_init_ctx(rdev, config);
 480
 481         if (IS_ERR(ctx))
 482                 return ERR_CAST(ctx);
 483
 484         return __devm_regmap_init(&rdev->dev, &regmap_sunxi_rsb, ctx, config,
 485                                   lock_key, lock_name);
 486 }
 487 EXPORT_SYMBOL_GPL(__devm_regmap_init_sunxi_rsb);
 488
 489 /* RSB controller driver functions */
 490 static irqreturn_t sunxi_rsb_irq(int irq, void *dev_id)
 491 {
 492         struct sunxi_rsb *rsb = dev_id;
 493         u32 status;
 494
 495         status = readl(rsb->regs + RSB_INTS);
 496         rsb->status = status;
 497
 498         /* Clear interrupts */
 499         status &= (RSB_INTS_LOAD_BSY | RSB_INTS_TRANS_ERR |
 500                    RSB_INTS_TRANS_OVER);
 501         writel(status, rsb->regs + RSB_INTS);
 502
 503         complete(&rsb->complete);
 504
 505         return IRQ_HANDLED;
 506 }
 507
 508 static int sunxi_rsb_init_device_mode(struct sunxi_rsb *rsb)
 509 {
 510         int ret = 0;
 511         u32 reg;
 512
 513         /* send init sequence */
 514         writel(RSB_DMCR_DEVICE_START | RSB_DMCR_MODE_DATA |
 515                RSB_DMCR_MODE_REG | RSB_DMCR_DEV_ADDR, rsb->regs + RSB_DMCR);
 516
 517         readl_poll_timeout(rsb->regs + RSB_DMCR, reg,
 518                            !(reg & RSB_DMCR_DEVICE_START), 100, 250000);
 519         if (reg & RSB_DMCR_DEVICE_START)
 520                 ret = -ETIMEDOUT;
 521
 522         /* clear interrupt status bits */
 523         writel(readl(rsb->regs + RSB_INTS), rsb->regs + RSB_INTS);
 524
 525         return ret;
 526 }
 527
 528 /*
 529  * There are 15 valid runtime addresses, though Allwinner typically
 530  * skips the first, for unknown reasons, and uses the following three.
 531  *
 532  * 0x17, 0x2d, 0x3a, 0x4e, 0x59, 0x63, 0x74, 0x8b,
 533  * 0x9c, 0xa6, 0xb1, 0xc5, 0xd2, 0xe8, 0xff
 534  *
 535  * No designs with 2 RSB slave devices sharing identical hardware
 536  * addresses on the same bus have been seen in the wild. All designs
 537  * use 0x2d for the primary PMIC, 0x3a for the secondary PMIC if
 538  * there is one, and 0x45 for peripheral ICs.
 539  *
 540  * The hardware does not seem to support re-setting runtime addresses.
 541  * Attempts to do so result in the slave devices returning a NACK.
 542  * Hence we just hardcode the mapping here, like Allwinner does.
 543  */
 544
 545 static const struct sunxi_rsb_addr_map sunxi_rsb_addr_maps[] = {
 546         { 0x3a3, 0x2d }, /* Primary PMIC: AXP223, AXP809, AXP81X, ... */
 547         { 0x745, 0x3a }, /* Secondary PMIC: AXP806, ... */
 548         { 0xe89, 0x4e }, /* Peripheral IC: AC100, ... */
 549 };
 550
 551 static u8 sunxi_rsb_get_rtaddr(u16 hwaddr)
 552 {
 553         int i;
 554
 555         for (i = 0; i < ARRAY_SIZE(sunxi_rsb_addr_maps); i++)
 556                 if (hwaddr == sunxi_rsb_addr_maps[i].hwaddr)
 557                         return sunxi_rsb_addr_maps[i].rtaddr;
 558
 559         return 0; /* 0 is an invalid runtime address */
 560 }
 561
 562 static int of_rsb_register_devices(struct sunxi_rsb *rsb)
 563 {
 564         struct device *dev = rsb->dev;
 565         struct device_node *child, *np = dev->of_node;
 566         u32 hwaddr;
 567         u8 rtaddr;
 568         int ret;
 569
 570         if (!np)
 571                 return -EINVAL;
 572
 573         /* Runtime addresses for all slaves should be set first */
 574         for_each_available_child_of_node(np, child) {
 575                 dev_dbg(dev, "setting child %pOF runtime address\n",
 576                         child);
 577
 578                 ret = of_property_read_u32(child, "reg", &hwaddr);
 579                 if (ret) {
 580                         dev_err(dev, "%pOF: invalid 'reg' property: %d\n",
 581                                 child, ret);
 582                         continue;
 583                 }
 584
 585                 rtaddr = sunxi_rsb_get_rtaddr(hwaddr);
 586                 if (!rtaddr) {
 587                         dev_err(dev, "%pOF: unknown hardware device address\n",
 588                                 child);
 589                         continue;
 590                 }
 591
 592                 /*
 593                  * Since no devices have been registered yet, we are the
 594                  * only ones using the bus, we can skip locking the bus.
 595                  */
 596
 597                 /* setup command parameters */
 598                 writel(RSB_CMD_STRA, rsb->regs + RSB_CMD);
 599                 writel(RSB_DAR_RTA(rtaddr) | RSB_DAR_DA(hwaddr),
 600                        rsb->regs + RSB_DAR);
 601
 602                 /* send command */
 603                 ret = _sunxi_rsb_run_xfer(rsb);
 604                 if (ret)
 605                         dev_warn(dev, "%pOF: set runtime address failed: %d\n",
 606                                  child, ret);
 607         }
 608
 609         /* Then we start adding devices and probing them */
 610         for_each_available_child_of_node(np, child) {
 611                 struct sunxi_rsb_device *rdev;
 612
 613                 dev_dbg(dev, "adding child %pOF\n", child);
 614
 615                 ret = of_property_read_u32(child, "reg", &hwaddr);
 616                 if (ret)
 617                         continue;
 618
 619                 rtaddr = sunxi_rsb_get_rtaddr(hwaddr);
 620                 if (!rtaddr)
 621                         continue;
 622
 623                 rdev = sunxi_rsb_device_create(rsb, child, hwaddr, rtaddr);
 624                 if (IS_ERR(rdev))
 625                         dev_err(dev, "failed to add child device %pOF: %ld\n",
 626                                 child, PTR_ERR(rdev));
 627         }
 628
 629         return 0;
 630 }
 631
 632 static int sunxi_rsb_hw_init(struct sunxi_rsb *rsb)
 633 {
 634         struct device *dev = rsb->dev;
 635         unsigned long p_clk_freq;
 636         u32 clk_delay, reg;
 637         int clk_div, ret;
 638
 639         ret = clk_prepare_enable(rsb->clk);
 640         if (ret) {
 641                 dev_err(dev, "failed to enable clk: %d\n", ret);
 642                 return ret;
 643         }
 644
 645         ret = reset_control_deassert(rsb->rstc);
 646         if (ret) {
 647                 dev_err(dev, "failed to deassert reset line: %d\n", ret);
 648                 goto err_clk_disable;
 649         }
 650
 651         /* reset the controller */
 652         writel(RSB_CTRL_SOFT_RST, rsb->regs + RSB_CTRL);
 653         readl_poll_timeout(rsb->regs + RSB_CTRL, reg,
 654                            !(reg & RSB_CTRL_SOFT_RST), 1000, 100000);
 655
 656         /*
 657          * Clock frequency and delay calculation code is from
 658          * Allwinner U-boot sources.
 659          *
 660          * From A83 user manual:
 661          * bus clock frequency = parent clock frequency / (2 * (divider + 1))
 662          */
 663         p_clk_freq = clk_get_rate(rsb->clk);
 664         clk_div = p_clk_freq / rsb->clk_freq / 2;
 665         if (!clk_div)
 666                 clk_div = 1;
 667         else if (clk_div > RSB_CCR_MAX_CLK_DIV + 1)
 668                 clk_div = RSB_CCR_MAX_CLK_DIV + 1;
 669
 670         clk_delay = clk_div >> 1;
 671         if (!clk_delay)
 672                 clk_delay = 1;
 673
 674         dev_info(dev, "RSB running at %lu Hz\n", p_clk_freq / clk_div / 2);
 675         writel(RSB_CCR_SDA_OUT_DELAY(clk_delay) | RSB_CCR_CLK_DIV(clk_div - 1),
 676                rsb->regs + RSB_CCR);
 677
 678         return 0;
 679
 680 err_clk_disable:
 681         clk_disable_unprepare(rsb->clk);
 682
 683         return ret;
 684 }
 685
 686 static void sunxi_rsb_hw_exit(struct sunxi_rsb *rsb)
 687 {
 688         reset_control_assert(rsb->rstc);
 689
 690         /* Keep the clock and PM reference counts consistent. */
 691         if (!pm_runtime_status_suspended(rsb->dev))
 692                 clk_disable_unprepare(rsb->clk);
 693 }
 694
 695 static int __maybe_unused sunxi_rsb_runtime_suspend(struct device *dev)
 696 {
 697         struct sunxi_rsb *rsb = dev_get_drvdata(dev);
 698
 699         clk_disable_unprepare(rsb->clk);
 700
 701         return 0;
 702 }
 703
 704 static int __maybe_unused sunxi_rsb_runtime_resume(struct device *dev)
 705 {
 706         struct sunxi_rsb *rsb = dev_get_drvdata(dev);
 707
 708         return clk_prepare_enable(rsb->clk);
 709 }
 710
 711 static int __maybe_unused sunxi_rsb_suspend(struct device *dev)
 712 {
 713         struct sunxi_rsb *rsb = dev_get_drvdata(dev);
 714
 715         sunxi_rsb_hw_exit(rsb);
 716
 717         return 0;
 718 }
 719
 720 static int __maybe_unused sunxi_rsb_resume(struct device *dev)
 721 {
 722         struct sunxi_rsb *rsb = dev_get_drvdata(dev);
 723
 724         return sunxi_rsb_hw_init(rsb);
 725 }
 726
 727 static int sunxi_rsb_probe(struct platform_device *pdev)
 728 {
 729         struct device *dev = &pdev->dev;
 730         struct device_node *np = dev->of_node;
 731         struct resource *r;
 732         struct sunxi_rsb *rsb;
 733         u32 clk_freq = 3000000;
 734         int irq, ret;
 735
 736         of_property_read_u32(np, "clock-frequency", &clk_freq);
 737         if (clk_freq > RSB_MAX_FREQ) {
 738                 dev_err(dev,
 739                         "clock-frequency (%u Hz) is too high (max = 20MHz)\n",
 740                         clk_freq);
 741                 return -EINVAL;
 742         }
 743
 744         rsb = devm_kzalloc(dev, sizeof(*rsb), GFP_KERNEL);
 745         if (!rsb)
 746                 return -ENOMEM;
 747
 748         rsb->dev = dev;
 749         rsb->clk_freq = clk_freq;
 750         platform_set_drvdata(pdev, rsb);
 751         r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 752         rsb->regs = devm_ioremap_resource(dev, r);
 753         if (IS_ERR(rsb->regs))
 754                 return PTR_ERR(rsb->regs);
 755
 756         irq = platform_get_irq(pdev, 0);
 757         if (irq < 0)
 758                 return irq;
 759
 760         rsb->clk = devm_clk_get(dev, NULL);
 761         if (IS_ERR(rsb->clk)) {
 762                 ret = PTR_ERR(rsb->clk);
 763                 dev_err(dev, "failed to retrieve clk: %d\n", ret);
 764                 return ret;
 765         }
 766
 767         rsb->rstc = devm_reset_control_get(dev, NULL);
 768         if (IS_ERR(rsb->rstc)) {
 769                 ret = PTR_ERR(rsb->rstc);
 770                 dev_err(dev, "failed to retrieve reset controller: %d\n", ret);
 771                 return ret;
 772         }
 773
 774         init_completion(&rsb->complete);
 775         mutex_init(&rsb->lock);
 776
 777         ret = devm_request_irq(dev, irq, sunxi_rsb_irq, 0, RSB_CTRL_NAME, rsb);
 778         if (ret) {
 779                 dev_err(dev, "can't register interrupt handler irq %d: %d\n",
 780                         irq, ret);
 781                 return ret;
 782         }
 783
 784         ret = sunxi_rsb_hw_init(rsb);
 785         if (ret)
 786                 return ret;
 787
 788         /* initialize all devices on the bus into RSB mode */
 789         ret = sunxi_rsb_init_device_mode(rsb);
 790         if (ret)
 791                 dev_warn(dev, "Initialize device mode failed: %d\n", ret);
 792
 793         pm_suspend_ignore_children(dev, true);
 794         pm_runtime_set_active(dev);
 795         pm_runtime_set_autosuspend_delay(dev, MSEC_PER_SEC);
 796         pm_runtime_use_autosuspend(dev);
 797         pm_runtime_enable(dev);
 798
 799         of_rsb_register_devices(rsb);
 800
 801         return 0;
 802 }
 803
 804 static int sunxi_rsb_remove(struct platform_device *pdev)
 805 {
 806         struct sunxi_rsb *rsb = platform_get_drvdata(pdev);
 807
 808         device_for_each_child(rsb->dev, NULL, sunxi_rsb_remove_devices);
 809         pm_runtime_disable(&pdev->dev);
 810         sunxi_rsb_hw_exit(rsb);
 811
 812         return 0;
 813 }
 814
 815 static void sunxi_rsb_shutdown(struct platform_device *pdev)
 816 {
 817         struct sunxi_rsb *rsb = platform_get_drvdata(pdev);
 818
 819         pm_runtime_disable(&pdev->dev);
 820         sunxi_rsb_hw_exit(rsb);
 821 }
 822
 823 static const struct dev_pm_ops sunxi_rsb_dev_pm_ops = {
 824         SET_RUNTIME_PM_OPS(sunxi_rsb_runtime_suspend,
 825                            sunxi_rsb_runtime_resume, NULL)
 826         SET_NOIRQ_SYSTEM_SLEEP_PM_OPS(sunxi_rsb_suspend, sunxi_rsb_resume)
 827 };
 828
 829 static const struct of_device_id sunxi_rsb_of_match_table[] = {
 830         { .compatible = "allwinner,sun8i-a23-rsb" },
 831         {}
 832 };
 833 MODULE_DEVICE_TABLE(of, sunxi_rsb_of_match_table);
 834
 835 static struct platform_driver sunxi_rsb_driver = {
 836         .probe = sunxi_rsb_probe,
 837         .remove = sunxi_rsb_remove,
 838         .shutdown = sunxi_rsb_shutdown,
 839         .driver = {
 840                 .name = RSB_CTRL_NAME,
 841                 .of_match_table = sunxi_rsb_of_match_table,
 842                 .pm = &sunxi_rsb_dev_pm_ops,
 843         },
 844 };
 845
 846 static int __init sunxi_rsb_init(void)
 847 {
 848         int ret;
 849
 850         ret = bus_register(&sunxi_rsb_bus);
 851         if (ret) {
 852                 pr_err("failed to register sunxi sunxi_rsb bus: %d\n", ret);
 853                 return ret;
 854         }
 855
 856         return platform_driver_register(&sunxi_rsb_driver);
 857 }
 858 module_init(sunxi_rsb_init);
 859
 860 static void __exit sunxi_rsb_exit(void)
 861 {
 862         platform_driver_unregister(&sunxi_rsb_driver);
 863         bus_unregister(&sunxi_rsb_bus);
 864 }
 865 module_exit(sunxi_rsb_exit);
 866
 867 MODULE_AUTHOR("Chen-Yu Tsai <wens@csie.org>");
 868 MODULE_DESCRIPTION("Allwinner sunXi Reduced Serial Bus controller driver");
 869 MODULE_LICENSE("GPL v2");