blob: ab3bde16ecb4443a2e63d8e327fa1db730294dff [file] [log] [blame]
James Hogan8286ae02015-03-25 15:39:50 +00001/*
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_setup() - Ensure the CDMM bus is initialised and usable.
336 * @bus: Pointer to bus information for current CPU.
337 * IS_ERR(bus) is checked, so no need for caller to check.
338 *
339 * The caller must prevent migration to another CPU, either by disabling
340 * pre-emption or by running from a pinned kernel thread.
341 *
342 * Returns 0 on success, -errno on failure.
343 */
344static int mips_cdmm_setup(struct mips_cdmm_bus *bus)
345{
346 unsigned long cdmmbase, flags;
347 int ret = 0;
348
349 if (IS_ERR(bus))
350 return PTR_ERR(bus);
351
352 local_irq_save(flags);
353 /* Don't set up bus a second time unless marked offline */
354 if (bus->offline) {
355 /* If CDMM region is still set up, nothing to do */
356 if (bus->phys == mips_cdmm_cur_base())
357 goto out;
358 /*
359 * The CDMM region isn't set up as expected, so it needs
360 * reconfiguring, but then we can stop checking it.
361 */
362 bus->offline = false;
363 } else if (bus->phys > 1) {
364 goto out;
365 }
366
367 /* If the CDMM region is already configured, inherit that setup */
368 if (!bus->phys)
369 bus->phys = mips_cdmm_cur_base();
370 /* Otherwise, ask platform code for suggestions */
371 if (!bus->phys && mips_cdmm_phys_base)
372 bus->phys = mips_cdmm_phys_base();
373 /* Otherwise, copy what other CPUs have done */
374 if (!bus->phys)
375 bus->phys = mips_cdmm_default_base;
376 /* Otherwise, complain once */
377 if (!bus->phys) {
378 bus->phys = 1;
379 /*
380 * If you hit this, either your bootloader needs to set up the
381 * CDMM on the boot CPU, or else you need to implement
382 * mips_cdmm_phys_base() for your platform (see asm/cdmm.h).
383 */
384 pr_err("cdmm%u: Failed to choose a physical base\n",
385 smp_processor_id());
386 }
387 /* Already complained? */
388 if (bus->phys == 1) {
389 ret = -ENOMEM;
390 goto out;
391 }
392 /* Record our success for other CPUs to copy */
393 mips_cdmm_default_base = bus->phys;
394
395 pr_debug("cdmm%u: Enabling CDMM region at %pa\n",
396 smp_processor_id(), &bus->phys);
397
398 /* Enable CDMM */
399 cdmmbase = read_c0_cdmmbase();
400 cdmmbase &= (1ul << MIPS_CDMMBASE_ADDR_SHIFT) - 1;
401 cdmmbase |= (bus->phys >> MIPS_CDMMBASE_ADDR_START)
402 << MIPS_CDMMBASE_ADDR_SHIFT;
403 cdmmbase |= MIPS_CDMMBASE_EN;
404 write_c0_cdmmbase(cdmmbase);
405 tlbw_use_hazard();
406
407 bus->regs = (void __iomem *)CKSEG1ADDR(bus->phys);
408 bus->drbs = 1 + ((cdmmbase & MIPS_CDMMBASE_SIZE) >>
409 MIPS_CDMMBASE_SIZE_SHIFT);
410 bus->drbs_reserved = !!(cdmmbase & MIPS_CDMMBASE_CI);
411
412out:
413 local_irq_restore(flags);
414 return ret;
415}
416
417/**
418 * mips_cdmm_early_probe() - Minimally probe for a specific device on CDMM.
419 * @dev_type: CDMM type code to look for.
420 *
421 * Minimally configure the in-CPU Common Device Memory Map (CDMM) and look for a
422 * specific device. This can be used to find a device very early in boot for
423 * example to configure an early FDC console device.
424 *
425 * The caller must prevent migration to another CPU, either by disabling
426 * pre-emption or by running from a pinned kernel thread.
427 *
428 * Returns: MMIO pointer to device memory. The caller can read the ACSR
429 * register to find more information about the device (such as the
430 * version number or the number of blocks).
431 * May return IOMEM_ERR_PTR(-errno) in case of error, so check with
432 * IS_ERR().
433 */
434void __iomem *mips_cdmm_early_probe(unsigned int dev_type)
435{
436 struct mips_cdmm_bus *bus;
437 void __iomem *cdmm;
438 u32 acsr;
439 unsigned int drb, type, size;
440 int err;
441
442 if (WARN_ON(!dev_type))
443 return IOMEM_ERR_PTR(-ENODEV);
444
445 bus = mips_cdmm_get_bus();
446 err = mips_cdmm_setup(bus);
447 if (err)
448 return IOMEM_ERR_PTR(err);
449
450 /* Skip the first block if it's reserved for more registers */
451 drb = bus->drbs_reserved;
452 cdmm = bus->regs;
453
454 /* Look for a specific device type */
455 for (; drb < bus->drbs; drb += size + 1) {
James Hogane21422d2015-04-28 10:57:29 +0100456 acsr = __raw_readl(cdmm + drb * CDMM_DRB_SIZE);
James Hogan8286ae02015-03-25 15:39:50 +0000457 type = (acsr & CDMM_ACSR_DEVTYPE) >> CDMM_ACSR_DEVTYPE_SHIFT;
458 if (type == dev_type)
459 return cdmm + drb * CDMM_DRB_SIZE;
460 size = (acsr & CDMM_ACSR_DEVSIZE) >> CDMM_ACSR_DEVSIZE_SHIFT;
461 }
462
463 return IOMEM_ERR_PTR(-ENODEV);
464}
465EXPORT_SYMBOL_GPL(mips_cdmm_early_probe);
466
467/**
468 * mips_cdmm_release() - Release a removed CDMM device.
469 * @dev: Device object
470 *
471 * Clean up the struct mips_cdmm_device for an unused CDMM device. This is
472 * called automatically by the driver core when a device is removed.
473 */
474static void mips_cdmm_release(struct device *dev)
475{
476 struct mips_cdmm_device *cdev = to_mips_cdmm_device(dev);
477
478 kfree(cdev);
479}
480
481/**
482 * mips_cdmm_bus_discover() - Discover the devices on the CDMM bus.
483 * @bus: CDMM bus information, must already be set up.
484 */
485static void mips_cdmm_bus_discover(struct mips_cdmm_bus *bus)
486{
487 void __iomem *cdmm;
488 u32 acsr;
489 unsigned int drb, type, size, rev;
490 struct mips_cdmm_device *dev;
491 unsigned int cpu = smp_processor_id();
492 int ret = 0;
493 int id = 0;
494
495 /* Skip the first block if it's reserved for more registers */
496 drb = bus->drbs_reserved;
497 cdmm = bus->regs;
498
499 /* Discover devices */
500 bus->discovered = true;
501 pr_info("cdmm%u discovery (%u blocks)\n", cpu, bus->drbs);
502 for (; drb < bus->drbs; drb += size + 1) {
James Hogane21422d2015-04-28 10:57:29 +0100503 acsr = __raw_readl(cdmm + drb * CDMM_DRB_SIZE);
James Hogan8286ae02015-03-25 15:39:50 +0000504 type = (acsr & CDMM_ACSR_DEVTYPE) >> CDMM_ACSR_DEVTYPE_SHIFT;
505 size = (acsr & CDMM_ACSR_DEVSIZE) >> CDMM_ACSR_DEVSIZE_SHIFT;
506 rev = (acsr & CDMM_ACSR_DEVREV) >> CDMM_ACSR_DEVREV_SHIFT;
507
508 if (!type)
509 continue;
510
511 pr_info("cdmm%u-%u: @%u (%#x..%#x), type 0x%02x, rev %u\n",
512 cpu, id, drb, drb * CDMM_DRB_SIZE,
513 (drb + size + 1) * CDMM_DRB_SIZE - 1,
514 type, rev);
515
516 dev = kzalloc(sizeof(*dev), GFP_KERNEL);
517 if (!dev)
518 break;
519
520 dev->cpu = cpu;
521 dev->res.start = bus->phys + drb * CDMM_DRB_SIZE;
522 dev->res.end = bus->phys +
523 (drb + size + 1) * CDMM_DRB_SIZE - 1;
524 dev->res.flags = IORESOURCE_MEM;
525 dev->type = type;
526 dev->rev = rev;
527 dev->dev.parent = get_cpu_device(cpu);
528 dev->dev.bus = &mips_cdmm_bustype;
529 dev->dev.id = atomic_inc_return(&mips_cdmm_next_id);
530 dev->dev.release = mips_cdmm_release;
531
532 dev_set_name(&dev->dev, "cdmm%u-%u", cpu, id);
533 ++id;
534 ret = device_register(&dev->dev);
535 if (ret) {
536 put_device(&dev->dev);
537 kfree(dev);
538 }
539 }
540}
541
542
543/*
544 * CPU hotplug and initialisation
545 *
546 * All the CDMM driver callbacks need to be executed on the appropriate CPU from
547 * workqueues. For the CPU callbacks, they need to be called for all devices on
548 * that CPU, so the work function calls bus_for_each_dev, using a helper
549 * (generated with BUILD_PERDEV_HELPER) to call the driver callback if the
550 * device's CPU matches.
551 */
552
553/**
554 * BUILD_PERDEV_HELPER() - Helper to call a CDMM driver callback if CPU matches.
555 * @_name: Name of CDMM driver callback function.
556 *
557 * Generates a bus_for_each_dev callback function to call a specific CDMM driver
558 * callback function for the device if the device's CPU matches that pointed to
559 * by the data argument.
560 *
561 * This is used for informing drivers for all devices on a given CPU of some
562 * event (such as the CPU going online/offline).
563 *
564 * It is expected to already be called from the appropriate CPU.
565 */
566#define BUILD_PERDEV_HELPER(_name) \
567static int mips_cdmm_##_name##_helper(struct device *dev, void *data) \
568{ \
569 struct mips_cdmm_device *cdev = to_mips_cdmm_device(dev); \
570 struct mips_cdmm_driver *cdrv; \
571 unsigned int cpu = *(unsigned int *)data; \
572 \
573 if (cdev->cpu != cpu || !dev->driver) \
574 return 0; \
575 \
576 cdrv = to_mips_cdmm_driver(dev->driver); \
577 if (!cdrv->_name) \
578 return 0; \
579 return cdrv->_name(cdev); \
580}
581
582/* bus_for_each_dev callback helper functions */
583BUILD_PERDEV_HELPER(cpu_down) /* int mips_cdmm_cpu_down_helper(...) */
584BUILD_PERDEV_HELPER(cpu_up) /* int mips_cdmm_cpu_up_helper(...) */
585
586/**
587 * mips_cdmm_bus_down() - Tear down the CDMM bus.
588 * @data: Pointer to unsigned int CPU number.
589 *
590 * This work_on_cpu callback function is executed on a given CPU to call the
591 * CDMM driver cpu_down callback for all devices on that CPU.
592 */
593static long mips_cdmm_bus_down(void *data)
594{
595 struct mips_cdmm_bus *bus;
596 long ret;
597
598 /* Inform all the devices on the bus */
599 ret = bus_for_each_dev(&mips_cdmm_bustype, NULL, data,
600 mips_cdmm_cpu_down_helper);
601
602 /*
603 * While bus is offline, each use of it should reconfigure it just in
604 * case it is first use when coming back online again.
605 */
606 bus = mips_cdmm_get_bus();
607 if (!IS_ERR(bus))
608 bus->offline = true;
609
610 return ret;
611}
612
613/**
614 * mips_cdmm_bus_up() - Bring up the CDMM bus.
615 * @data: Pointer to unsigned int CPU number.
616 *
617 * This work_on_cpu callback function is executed on a given CPU to discover
618 * CDMM devices on that CPU, or to call the CDMM driver cpu_up callback for all
619 * devices already discovered on that CPU.
620 *
621 * It is used during initialisation and when CPUs are brought online.
622 */
623static long mips_cdmm_bus_up(void *data)
624{
625 struct mips_cdmm_bus *bus;
626 long ret;
627
628 bus = mips_cdmm_get_bus();
629 ret = mips_cdmm_setup(bus);
630 if (ret)
631 return ret;
632
633 /* Bus now set up, so we can drop the offline flag if still set */
634 bus->offline = false;
635
636 if (!bus->discovered)
637 mips_cdmm_bus_discover(bus);
638 else
639 /* Inform all the devices on the bus */
640 ret = bus_for_each_dev(&mips_cdmm_bustype, NULL, data,
641 mips_cdmm_cpu_up_helper);
642
643 return ret;
644}
645
646/**
647 * mips_cdmm_cpu_notify() - Take action when a CPU is going online or offline.
648 * @nb: CPU notifier block .
649 * @action: Event that has taken place (CPU_*).
650 * @data: CPU number.
651 *
652 * This notifier is used to keep the CDMM buses updated as CPUs are offlined and
653 * onlined. When CPUs go offline or come back online, so does their CDMM bus, so
654 * devices must be informed. Also when CPUs come online for the first time the
655 * devices on the CDMM bus need discovering.
656 *
657 * Returns: NOTIFY_OK if event was used.
658 * NOTIFY_DONE if we didn't care.
659 */
660static int mips_cdmm_cpu_notify(struct notifier_block *nb,
661 unsigned long action, void *data)
662{
663 unsigned int cpu = (unsigned int)data;
664
665 switch (action & ~CPU_TASKS_FROZEN) {
666 case CPU_ONLINE:
667 case CPU_DOWN_FAILED:
668 work_on_cpu(cpu, mips_cdmm_bus_up, &cpu);
669 break;
670 case CPU_DOWN_PREPARE:
671 work_on_cpu(cpu, mips_cdmm_bus_down, &cpu);
672 break;
673 default:
674 return NOTIFY_DONE;
675 }
676
677 return NOTIFY_OK;
678}
679
680static struct notifier_block mips_cdmm_cpu_nb = {
681 .notifier_call = mips_cdmm_cpu_notify,
682};
683
684/**
685 * mips_cdmm_init() - Initialise CDMM bus.
686 *
687 * Initialise CDMM bus, discover CDMM devices for online CPUs, and arrange for
688 * hotplug notifications so the CDMM drivers can be kept up to date.
689 */
690static int __init mips_cdmm_init(void)
691{
692 unsigned int cpu;
693 int ret;
694
695 /* Register the bus */
696 ret = bus_register(&mips_cdmm_bustype);
697 if (ret)
698 return ret;
699
700 /* We want to be notified about new CPUs */
701 ret = register_cpu_notifier(&mips_cdmm_cpu_nb);
702 if (ret) {
703 pr_warn("cdmm: Failed to register CPU notifier\n");
704 goto out;
705 }
706
707 /* Discover devices on CDMM of online CPUs */
708 for_each_online_cpu(cpu)
709 work_on_cpu(cpu, mips_cdmm_bus_up, &cpu);
710
711 return 0;
712out:
713 bus_unregister(&mips_cdmm_bustype);
714 return ret;
715}
716subsys_initcall(mips_cdmm_init);