1/* 2 * Bus driver for MIPS Common Device Memory Map (CDMM). 3 * 4 * Copyright (C) 2014-2015 Imagination Technologies Ltd. 5 * 6 * This file is subject to the terms and conditions of the GNU General Public 7 * License. See the file "COPYING" in the main directory of this archive 8 * for more details. 9 */ 10 11#include <linux/atomic.h> 12#include <linux/err.h> 13#include <linux/cpu.h> 14#include <linux/cpumask.h> 15#include <linux/io.h> 16#include <linux/platform_device.h> 17#include <linux/slab.h> 18#include <linux/smp.h> 19#include <asm/cdmm.h> 20#include <asm/hazards.h> 21#include <asm/mipsregs.h> 22 23/* Access control and status register fields */ 24#define CDMM_ACSR_DEVTYPE_SHIFT 24 25#define CDMM_ACSR_DEVTYPE (255ul << CDMM_ACSR_DEVTYPE_SHIFT) 26#define CDMM_ACSR_DEVSIZE_SHIFT 16 27#define CDMM_ACSR_DEVSIZE (31ul << CDMM_ACSR_DEVSIZE_SHIFT) 28#define CDMM_ACSR_DEVREV_SHIFT 12 29#define CDMM_ACSR_DEVREV (15ul << CDMM_ACSR_DEVREV_SHIFT) 30#define CDMM_ACSR_UW (1ul << 3) 31#define CDMM_ACSR_UR (1ul << 2) 32#define CDMM_ACSR_SW (1ul << 1) 33#define CDMM_ACSR_SR (1ul << 0) 34 35/* Each block of device registers is 64 bytes */ 36#define CDMM_DRB_SIZE 64 37 38#define to_mips_cdmm_driver(d) container_of(d, struct mips_cdmm_driver, drv) 39 40/* Default physical base address */ 41static phys_addr_t mips_cdmm_default_base; 42 43/* Bus operations */ 44 45static const struct mips_cdmm_device_id * 46mips_cdmm_lookup(const struct mips_cdmm_device_id *table, 47 struct mips_cdmm_device *dev) 48{ 49 int ret = 0; 50 51 for (; table->type; ++table) { 52 ret = (dev->type == table->type); 53 if (ret) 54 break; 55 } 56 57 return ret ? table : NULL; 58} 59 60static int mips_cdmm_match(struct device *dev, struct device_driver *drv) 61{ 62 struct mips_cdmm_device *cdev = to_mips_cdmm_device(dev); 63 struct mips_cdmm_driver *cdrv = to_mips_cdmm_driver(drv); 64 65 return mips_cdmm_lookup(cdrv->id_table, cdev) != NULL; 66} 67 68static int mips_cdmm_uevent(struct device *dev, struct kobj_uevent_env *env) 69{ 70 struct mips_cdmm_device *cdev = to_mips_cdmm_device(dev); 71 int retval = 0; 72 73 retval = add_uevent_var(env, "CDMM_CPU=%u", cdev->cpu); 74 if (retval) 75 return retval; 76 77 retval = add_uevent_var(env, "CDMM_TYPE=0x%02x", cdev->type); 78 if (retval) 79 return retval; 80 81 retval = add_uevent_var(env, "CDMM_REV=%u", cdev->rev); 82 if (retval) 83 return retval; 84 85 retval = add_uevent_var(env, "MODALIAS=mipscdmm:t%02X", cdev->type); 86 return retval; 87} 88 89/* Device attributes */ 90 91#define CDMM_ATTR(name, fmt, arg...) \ 92static ssize_t name##_show(struct device *_dev, \ 93 struct device_attribute *attr, char *buf) \ 94{ \ 95 struct mips_cdmm_device *dev = to_mips_cdmm_device(_dev); \ 96 return sprintf(buf, fmt, arg); \ 97} \ 98static DEVICE_ATTR_RO(name); 99 100CDMM_ATTR(cpu, "%u\n", dev->cpu); 101CDMM_ATTR(type, "0x%02x\n", dev->type); 102CDMM_ATTR(revision, "%u\n", dev->rev); 103CDMM_ATTR(modalias, "mipscdmm:t%02X\n", dev->type); 104CDMM_ATTR(resource, "\t%016llx\t%016llx\t%016lx\n", 105 (unsigned long long)dev->res.start, 106 (unsigned long long)dev->res.end, 107 dev->res.flags); 108 109static struct attribute *mips_cdmm_dev_attrs[] = { 110 &dev_attr_cpu.attr, 111 &dev_attr_type.attr, 112 &dev_attr_revision.attr, 113 &dev_attr_modalias.attr, 114 &dev_attr_resource.attr, 115 NULL, 116}; 117ATTRIBUTE_GROUPS(mips_cdmm_dev); 118 119struct bus_type mips_cdmm_bustype = { 120 .name = "cdmm", 121 .dev_groups = mips_cdmm_dev_groups, 122 .match = mips_cdmm_match, 123 .uevent = mips_cdmm_uevent, 124}; 125EXPORT_SYMBOL_GPL(mips_cdmm_bustype); 126 127/* 128 * Standard driver callback helpers. 129 * 130 * All the CDMM driver callbacks need to be executed on the appropriate CPU from 131 * workqueues. For the standard driver callbacks we need a work function 132 * (mips_cdmm_{void,int}_work()) to do the actual call from the right CPU, and a 133 * wrapper function (generated with BUILD_PERCPU_HELPER) to arrange for the work 134 * function to be called on that CPU. 135 */ 136 137/** 138 * struct mips_cdmm_work_dev - Data for per-device call work. 139 * @fn: CDMM driver callback function to call for the device. 140 * @dev: CDMM device to pass to @fn. 141 */ 142struct mips_cdmm_work_dev { 143 void *fn; 144 struct mips_cdmm_device *dev; 145}; 146 147/** 148 * mips_cdmm_void_work() - Call a void returning CDMM driver callback. 149 * @data: struct mips_cdmm_work_dev pointer. 150 * 151 * A work_on_cpu() callback function to call an arbitrary CDMM driver callback 152 * function which doesn't return a value. 153 */ 154static long mips_cdmm_void_work(void *data) 155{ 156 struct mips_cdmm_work_dev *work = data; 157 void (*fn)(struct mips_cdmm_device *) = work->fn; 158 159 fn(work->dev); 160 return 0; 161} 162 163/** 164 * mips_cdmm_int_work() - Call an int returning CDMM driver callback. 165 * @data: struct mips_cdmm_work_dev pointer. 166 * 167 * A work_on_cpu() callback function to call an arbitrary CDMM driver callback 168 * function which returns an int. 169 */ 170static long mips_cdmm_int_work(void *data) 171{ 172 struct mips_cdmm_work_dev *work = data; 173 int (*fn)(struct mips_cdmm_device *) = work->fn; 174 175 return fn(work->dev); 176} 177 178#define _BUILD_RET_void 179#define _BUILD_RET_int return 180 181/** 182 * BUILD_PERCPU_HELPER() - Helper to call a CDMM driver callback on right CPU. 183 * @_ret: Return type (void or int). 184 * @_name: Name of CDMM driver callback function. 185 * 186 * Generates a specific device callback function to call a CDMM driver callback 187 * function on the appropriate CPU for the device, and if applicable return the 188 * result. 189 */ 190#define BUILD_PERCPU_HELPER(_ret, _name) \ 191static _ret mips_cdmm_##_name(struct device *dev) \ 192{ \ 193 struct mips_cdmm_device *cdev = to_mips_cdmm_device(dev); \ 194 struct mips_cdmm_driver *cdrv = to_mips_cdmm_driver(dev->driver); \ 195 struct mips_cdmm_work_dev work = { \ 196 .fn = cdrv->_name, \ 197 .dev = cdev, \ 198 }; \ 199 \ 200 _BUILD_RET_##_ret work_on_cpu(cdev->cpu, \ 201 mips_cdmm_##_ret##_work, &work); \ 202} 203 204/* Driver callback functions */ 205BUILD_PERCPU_HELPER(int, probe) /* int mips_cdmm_probe(struct device) */ 206BUILD_PERCPU_HELPER(int, remove) /* int mips_cdmm_remove(struct device) */ 207BUILD_PERCPU_HELPER(void, shutdown) /* void mips_cdmm_shutdown(struct device) */ 208 209 210/* Driver registration */ 211 212/** 213 * mips_cdmm_driver_register() - Register a CDMM driver. 214 * @drv: CDMM driver information. 215 * 216 * Register a CDMM driver with the CDMM subsystem. The driver will be informed 217 * of matching devices which are discovered. 218 * 219 * Returns: 0 on success. 220 */ 221int mips_cdmm_driver_register(struct mips_cdmm_driver *drv) 222{ 223 drv->drv.bus = &mips_cdmm_bustype; 224 225 if (drv->probe) 226 drv->drv.probe = mips_cdmm_probe; 227 if (drv->remove) 228 drv->drv.remove = mips_cdmm_remove; 229 if (drv->shutdown) 230 drv->drv.shutdown = mips_cdmm_shutdown; 231 232 return driver_register(&drv->drv); 233} 234EXPORT_SYMBOL_GPL(mips_cdmm_driver_register); 235 236/** 237 * mips_cdmm_driver_unregister() - Unregister a CDMM driver. 238 * @drv: CDMM driver information. 239 * 240 * Unregister a CDMM driver from the CDMM subsystem. 241 */ 242void mips_cdmm_driver_unregister(struct mips_cdmm_driver *drv) 243{ 244 driver_unregister(&drv->drv); 245} 246EXPORT_SYMBOL_GPL(mips_cdmm_driver_unregister); 247 248 249/* CDMM initialisation and bus discovery */ 250 251/** 252 * struct mips_cdmm_bus - Info about CDMM bus. 253 * @phys: Physical address at which it is mapped. 254 * @regs: Virtual address where registers can be accessed. 255 * @drbs: Total number of DRBs. 256 * @drbs_reserved: Number of DRBs reserved. 257 * @discovered: Whether the devices on the bus have been discovered yet. 258 * @offline: Whether the CDMM bus is going offline (or very early 259 * coming back online), in which case it should be 260 * reconfigured each time. 261 */ 262struct mips_cdmm_bus { 263 phys_addr_t phys; 264 void __iomem *regs; 265 unsigned int drbs; 266 unsigned int drbs_reserved; 267 bool discovered; 268 bool offline; 269}; 270 271static struct mips_cdmm_bus mips_cdmm_boot_bus; 272static DEFINE_PER_CPU(struct mips_cdmm_bus *, mips_cdmm_buses); 273static atomic_t mips_cdmm_next_id = ATOMIC_INIT(-1); 274 275/** 276 * mips_cdmm_get_bus() - Get the per-CPU CDMM bus information. 277 * 278 * Get information about the per-CPU CDMM bus, if the bus is present. 279 * 280 * The caller must prevent migration to another CPU, either by disabling 281 * pre-emption or by running from a pinned kernel thread. 282 * 283 * Returns: Pointer to CDMM bus information for the current CPU. 284 * May return ERR_PTR(-errno) in case of error, so check with 285 * IS_ERR(). 286 */ 287static struct mips_cdmm_bus *mips_cdmm_get_bus(void) 288{ 289 struct mips_cdmm_bus *bus, **bus_p; 290 unsigned long flags; 291 unsigned int cpu; 292 293 if (!cpu_has_cdmm) 294 return ERR_PTR(-ENODEV); 295 296 cpu = smp_processor_id(); 297 /* Avoid early use of per-cpu primitives before initialised */ 298 if (cpu == 0) 299 return &mips_cdmm_boot_bus; 300 301 /* Get bus pointer */ 302 bus_p = per_cpu_ptr(&mips_cdmm_buses, cpu); 303 local_irq_save(flags); 304 bus = *bus_p; 305 /* Attempt allocation if NULL */ 306 if (unlikely(!bus)) { 307 bus = kzalloc(sizeof(*bus), GFP_ATOMIC); 308 if (unlikely(!bus)) 309 bus = ERR_PTR(-ENOMEM); 310 else 311 *bus_p = bus; 312 } 313 local_irq_restore(flags); 314 return bus; 315} 316 317/** 318 * mips_cdmm_cur_base() - Find current physical base address of CDMM region. 319 * 320 * Returns: Physical base address of CDMM region according to cdmmbase CP0 321 * register, or 0 if the CDMM region is disabled. 322 */ 323static phys_addr_t mips_cdmm_cur_base(void) 324{ 325 unsigned long cdmmbase = read_c0_cdmmbase(); 326 327 if (!(cdmmbase & MIPS_CDMMBASE_EN)) 328 return 0; 329 330 return (cdmmbase >> MIPS_CDMMBASE_ADDR_SHIFT) 331 << MIPS_CDMMBASE_ADDR_START; 332} 333 334/** 335 * mips_cdmm_phys_base() - Choose a physical base address for CDMM region. 336 * 337 * Picking a suitable physical address at which to map the CDMM region is 338 * platform specific, so this weak function can be overridden by platform 339 * code to pick a suitable value if none is configured by the bootloader. 340 */ 341phys_addr_t __weak mips_cdmm_phys_base(void) 342{ 343 return 0; 344} 345 346/** 347 * mips_cdmm_setup() - Ensure the CDMM bus is initialised and usable. 348 * @bus: Pointer to bus information for current CPU. 349 * IS_ERR(bus) is checked, so no need for caller to check. 350 * 351 * The caller must prevent migration to another CPU, either by disabling 352 * pre-emption or by running from a pinned kernel thread. 353 * 354 * Returns 0 on success, -errno on failure. 355 */ 356static int mips_cdmm_setup(struct mips_cdmm_bus *bus) 357{ 358 unsigned long cdmmbase, flags; 359 int ret = 0; 360 361 if (IS_ERR(bus)) 362 return PTR_ERR(bus); 363 364 local_irq_save(flags); 365 /* Don't set up bus a second time unless marked offline */ 366 if (bus->offline) { 367 /* If CDMM region is still set up, nothing to do */ 368 if (bus->phys == mips_cdmm_cur_base()) 369 goto out; 370 /* 371 * The CDMM region isn't set up as expected, so it needs 372 * reconfiguring, but then we can stop checking it. 373 */ 374 bus->offline = false; 375 } else if (bus->phys > 1) { 376 goto out; 377 } 378 379 /* If the CDMM region is already configured, inherit that setup */ 380 if (!bus->phys) 381 bus->phys = mips_cdmm_cur_base(); 382 /* Otherwise, ask platform code for suggestions */ 383 if (!bus->phys) 384 bus->phys = mips_cdmm_phys_base(); 385 /* Otherwise, copy what other CPUs have done */ 386 if (!bus->phys) 387 bus->phys = mips_cdmm_default_base; 388 /* Otherwise, complain once */ 389 if (!bus->phys) { 390 bus->phys = 1; 391 /* 392 * If you hit this, either your bootloader needs to set up the 393 * CDMM on the boot CPU, or else you need to implement 394 * mips_cdmm_phys_base() for your platform (see asm/cdmm.h). 395 */ 396 pr_err("cdmm%u: Failed to choose a physical base\n", 397 smp_processor_id()); 398 } 399 /* Already complained? */ 400 if (bus->phys == 1) { 401 ret = -ENOMEM; 402 goto out; 403 } 404 /* Record our success for other CPUs to copy */ 405 mips_cdmm_default_base = bus->phys; 406 407 pr_debug("cdmm%u: Enabling CDMM region at %pa\n", 408 smp_processor_id(), &bus->phys); 409 410 /* Enable CDMM */ 411 cdmmbase = read_c0_cdmmbase(); 412 cdmmbase &= (1ul << MIPS_CDMMBASE_ADDR_SHIFT) - 1; 413 cdmmbase |= (bus->phys >> MIPS_CDMMBASE_ADDR_START) 414 << MIPS_CDMMBASE_ADDR_SHIFT; 415 cdmmbase |= MIPS_CDMMBASE_EN; 416 write_c0_cdmmbase(cdmmbase); 417 tlbw_use_hazard(); 418 419 bus->regs = (void __iomem *)CKSEG1ADDR(bus->phys); 420 bus->drbs = 1 + ((cdmmbase & MIPS_CDMMBASE_SIZE) >> 421 MIPS_CDMMBASE_SIZE_SHIFT); 422 bus->drbs_reserved = !!(cdmmbase & MIPS_CDMMBASE_CI); 423 424out: 425 local_irq_restore(flags); 426 return ret; 427} 428 429/** 430 * mips_cdmm_early_probe() - Minimally probe for a specific device on CDMM. 431 * @dev_type: CDMM type code to look for. 432 * 433 * Minimally configure the in-CPU Common Device Memory Map (CDMM) and look for a 434 * specific device. This can be used to find a device very early in boot for 435 * example to configure an early FDC console device. 436 * 437 * The caller must prevent migration to another CPU, either by disabling 438 * pre-emption or by running from a pinned kernel thread. 439 * 440 * Returns: MMIO pointer to device memory. The caller can read the ACSR 441 * register to find more information about the device (such as the 442 * version number or the number of blocks). 443 * May return IOMEM_ERR_PTR(-errno) in case of error, so check with 444 * IS_ERR(). 445 */ 446void __iomem *mips_cdmm_early_probe(unsigned int dev_type) 447{ 448 struct mips_cdmm_bus *bus; 449 void __iomem *cdmm; 450 u32 acsr; 451 unsigned int drb, type, size; 452 int err; 453 454 if (WARN_ON(!dev_type)) 455 return IOMEM_ERR_PTR(-ENODEV); 456 457 bus = mips_cdmm_get_bus(); 458 err = mips_cdmm_setup(bus); 459 if (err) 460 return IOMEM_ERR_PTR(err); 461 462 /* Skip the first block if it's reserved for more registers */ 463 drb = bus->drbs_reserved; 464 cdmm = bus->regs; 465 466 /* Look for a specific device type */ 467 for (; drb < bus->drbs; drb += size + 1) { 468 acsr = __raw_readl(cdmm + drb * CDMM_DRB_SIZE); 469 type = (acsr & CDMM_ACSR_DEVTYPE) >> CDMM_ACSR_DEVTYPE_SHIFT; 470 if (type == dev_type) 471 return cdmm + drb * CDMM_DRB_SIZE; 472 size = (acsr & CDMM_ACSR_DEVSIZE) >> CDMM_ACSR_DEVSIZE_SHIFT; 473 } 474 475 return IOMEM_ERR_PTR(-ENODEV); 476} 477EXPORT_SYMBOL_GPL(mips_cdmm_early_probe); 478 479/** 480 * mips_cdmm_release() - Release a removed CDMM device. 481 * @dev: Device object 482 * 483 * Clean up the struct mips_cdmm_device for an unused CDMM device. This is 484 * called automatically by the driver core when a device is removed. 485 */ 486static void mips_cdmm_release(struct device *dev) 487{ 488 struct mips_cdmm_device *cdev = to_mips_cdmm_device(dev); 489 490 kfree(cdev); 491} 492 493/** 494 * mips_cdmm_bus_discover() - Discover the devices on the CDMM bus. 495 * @bus: CDMM bus information, must already be set up. 496 */ 497static void mips_cdmm_bus_discover(struct mips_cdmm_bus *bus) 498{ 499 void __iomem *cdmm; 500 u32 acsr; 501 unsigned int drb, type, size, rev; 502 struct mips_cdmm_device *dev; 503 unsigned int cpu = smp_processor_id(); 504 int ret = 0; 505 int id = 0; 506 507 /* Skip the first block if it's reserved for more registers */ 508 drb = bus->drbs_reserved; 509 cdmm = bus->regs; 510 511 /* Discover devices */ 512 bus->discovered = true; 513 pr_info("cdmm%u discovery (%u blocks)\n", cpu, bus->drbs); 514 for (; drb < bus->drbs; drb += size + 1) { 515 acsr = __raw_readl(cdmm + drb * CDMM_DRB_SIZE); 516 type = (acsr & CDMM_ACSR_DEVTYPE) >> CDMM_ACSR_DEVTYPE_SHIFT; 517 size = (acsr & CDMM_ACSR_DEVSIZE) >> CDMM_ACSR_DEVSIZE_SHIFT; 518 rev = (acsr & CDMM_ACSR_DEVREV) >> CDMM_ACSR_DEVREV_SHIFT; 519 520 if (!type) 521 continue; 522 523 pr_info("cdmm%u-%u: @%u (%#x..%#x), type 0x%02x, rev %u\n", 524 cpu, id, drb, drb * CDMM_DRB_SIZE, 525 (drb + size + 1) * CDMM_DRB_SIZE - 1, 526 type, rev); 527 528 dev = kzalloc(sizeof(*dev), GFP_KERNEL); 529 if (!dev) 530 break; 531 532 dev->cpu = cpu; 533 dev->res.start = bus->phys + drb * CDMM_DRB_SIZE; 534 dev->res.end = bus->phys + 535 (drb + size + 1) * CDMM_DRB_SIZE - 1; 536 dev->res.flags = IORESOURCE_MEM; 537 dev->type = type; 538 dev->rev = rev; 539 dev->dev.parent = get_cpu_device(cpu); 540 dev->dev.bus = &mips_cdmm_bustype; 541 dev->dev.id = atomic_inc_return(&mips_cdmm_next_id); 542 dev->dev.release = mips_cdmm_release; 543 544 dev_set_name(&dev->dev, "cdmm%u-%u", cpu, id); 545 ++id; 546 ret = device_register(&dev->dev); 547 if (ret) { 548 put_device(&dev->dev); 549 kfree(dev); 550 } 551 } 552} 553 554 555/* 556 * CPU hotplug and initialisation 557 * 558 * All the CDMM driver callbacks need to be executed on the appropriate CPU from 559 * workqueues. For the CPU callbacks, they need to be called for all devices on 560 * that CPU, so the work function calls bus_for_each_dev, using a helper 561 * (generated with BUILD_PERDEV_HELPER) to call the driver callback if the 562 * device's CPU matches. 563 */ 564 565/** 566 * BUILD_PERDEV_HELPER() - Helper to call a CDMM driver callback if CPU matches. 567 * @_name: Name of CDMM driver callback function. 568 * 569 * Generates a bus_for_each_dev callback function to call a specific CDMM driver 570 * callback function for the device if the device's CPU matches that pointed to 571 * by the data argument. 572 * 573 * This is used for informing drivers for all devices on a given CPU of some 574 * event (such as the CPU going online/offline). 575 * 576 * It is expected to already be called from the appropriate CPU. 577 */ 578#define BUILD_PERDEV_HELPER(_name) \ 579static int mips_cdmm_##_name##_helper(struct device *dev, void *data) \ 580{ \ 581 struct mips_cdmm_device *cdev = to_mips_cdmm_device(dev); \ 582 struct mips_cdmm_driver *cdrv; \ 583 unsigned int cpu = *(unsigned int *)data; \ 584 \ 585 if (cdev->cpu != cpu || !dev->driver) \ 586 return 0; \ 587 \ 588 cdrv = to_mips_cdmm_driver(dev->driver); \ 589 if (!cdrv->_name) \ 590 return 0; \ 591 return cdrv->_name(cdev); \ 592} 593 594/* bus_for_each_dev callback helper functions */ 595BUILD_PERDEV_HELPER(cpu_down) /* int mips_cdmm_cpu_down_helper(...) */ 596BUILD_PERDEV_HELPER(cpu_up) /* int mips_cdmm_cpu_up_helper(...) */ 597 598/** 599 * mips_cdmm_bus_down() - Tear down the CDMM bus. 600 * @data: Pointer to unsigned int CPU number. 601 * 602 * This work_on_cpu callback function is executed on a given CPU to call the 603 * CDMM driver cpu_down callback for all devices on that CPU. 604 */ 605static long mips_cdmm_bus_down(void *data) 606{ 607 struct mips_cdmm_bus *bus; 608 long ret; 609 610 /* Inform all the devices on the bus */ 611 ret = bus_for_each_dev(&mips_cdmm_bustype, NULL, data, 612 mips_cdmm_cpu_down_helper); 613 614 /* 615 * While bus is offline, each use of it should reconfigure it just in 616 * case it is first use when coming back online again. 617 */ 618 bus = mips_cdmm_get_bus(); 619 if (!IS_ERR(bus)) 620 bus->offline = true; 621 622 return ret; 623} 624 625/** 626 * mips_cdmm_bus_up() - Bring up the CDMM bus. 627 * @data: Pointer to unsigned int CPU number. 628 * 629 * This work_on_cpu callback function is executed on a given CPU to discover 630 * CDMM devices on that CPU, or to call the CDMM driver cpu_up callback for all 631 * devices already discovered on that CPU. 632 * 633 * It is used during initialisation and when CPUs are brought online. 634 */ 635static long mips_cdmm_bus_up(void *data) 636{ 637 struct mips_cdmm_bus *bus; 638 long ret; 639 640 bus = mips_cdmm_get_bus(); 641 ret = mips_cdmm_setup(bus); 642 if (ret) 643 return ret; 644 645 /* Bus now set up, so we can drop the offline flag if still set */ 646 bus->offline = false; 647 648 if (!bus->discovered) 649 mips_cdmm_bus_discover(bus); 650 else 651 /* Inform all the devices on the bus */ 652 ret = bus_for_each_dev(&mips_cdmm_bustype, NULL, data, 653 mips_cdmm_cpu_up_helper); 654 655 return ret; 656} 657 658/** 659 * mips_cdmm_cpu_notify() - Take action when a CPU is going online or offline. 660 * @nb: CPU notifier block . 661 * @action: Event that has taken place (CPU_*). 662 * @data: CPU number. 663 * 664 * This notifier is used to keep the CDMM buses updated as CPUs are offlined and 665 * onlined. When CPUs go offline or come back online, so does their CDMM bus, so 666 * devices must be informed. Also when CPUs come online for the first time the 667 * devices on the CDMM bus need discovering. 668 * 669 * Returns: NOTIFY_OK if event was used. 670 * NOTIFY_DONE if we didn't care. 671 */ 672static int mips_cdmm_cpu_notify(struct notifier_block *nb, 673 unsigned long action, void *data) 674{ 675 unsigned int cpu = (unsigned int)data; 676 677 switch (action & ~CPU_TASKS_FROZEN) { 678 case CPU_ONLINE: 679 case CPU_DOWN_FAILED: 680 work_on_cpu(cpu, mips_cdmm_bus_up, &cpu); 681 break; 682 case CPU_DOWN_PREPARE: 683 work_on_cpu(cpu, mips_cdmm_bus_down, &cpu); 684 break; 685 default: 686 return NOTIFY_DONE; 687 } 688 689 return NOTIFY_OK; 690} 691 692static struct notifier_block mips_cdmm_cpu_nb = { 693 .notifier_call = mips_cdmm_cpu_notify, 694}; 695 696/** 697 * mips_cdmm_init() - Initialise CDMM bus. 698 * 699 * Initialise CDMM bus, discover CDMM devices for online CPUs, and arrange for 700 * hotplug notifications so the CDMM drivers can be kept up to date. 701 */ 702static int __init mips_cdmm_init(void) 703{ 704 unsigned int cpu; 705 int ret; 706 707 /* Register the bus */ 708 ret = bus_register(&mips_cdmm_bustype); 709 if (ret) 710 return ret; 711 712 /* We want to be notified about new CPUs */ 713 ret = register_cpu_notifier(&mips_cdmm_cpu_nb); 714 if (ret) { 715 pr_warn("cdmm: Failed to register CPU notifier\n"); 716 goto out; 717 } 718 719 /* Discover devices on CDMM of online CPUs */ 720 for_each_online_cpu(cpu) 721 work_on_cpu(cpu, mips_cdmm_bus_up, &cpu); 722 723 return 0; 724out: 725 bus_unregister(&mips_cdmm_bustype); 726 return ret; 727} 728subsys_initcall(mips_cdmm_init); 729