xref: /linux/arch/x86/platform/intel/iosf_mbi.c (revision a1ff5a7d78a036d6c2178ee5acd6ba4946243800)
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * IOSF-SB MailBox Interface Driver
4  * Copyright (c) 2013, Intel Corporation.
5  *
6  * The IOSF-SB is a fabric bus available on Atom based SOC's that uses a
7  * mailbox interface (MBI) to communicate with multiple devices. This
8  * driver implements access to this interface for those platforms that can
9  * enumerate the device using PCI.
10  */
11 
12 #include <linux/delay.h>
13 #include <linux/module.h>
14 #include <linux/init.h>
15 #include <linux/spinlock.h>
16 #include <linux/pci.h>
17 #include <linux/debugfs.h>
18 #include <linux/capability.h>
19 #include <linux/pm_qos.h>
20 #include <linux/wait.h>
21 
22 #include <asm/iosf_mbi.h>
23 
24 #define PCI_DEVICE_ID_INTEL_BAYTRAIL		0x0F00
25 #define PCI_DEVICE_ID_INTEL_BRASWELL		0x2280
26 #define PCI_DEVICE_ID_INTEL_QUARK_X1000		0x0958
27 #define PCI_DEVICE_ID_INTEL_TANGIER		0x1170
28 
29 static struct pci_dev *mbi_pdev;
30 static DEFINE_SPINLOCK(iosf_mbi_lock);
31 
32 /**************** Generic iosf_mbi access helpers ****************/
33 
iosf_mbi_form_mcr(u8 op,u8 port,u8 offset)34 static inline u32 iosf_mbi_form_mcr(u8 op, u8 port, u8 offset)
35 {
36 	return (op << 24) | (port << 16) | (offset << 8) | MBI_ENABLE;
37 }
38 
iosf_mbi_pci_read_mdr(u32 mcrx,u32 mcr,u32 * mdr)39 static int iosf_mbi_pci_read_mdr(u32 mcrx, u32 mcr, u32 *mdr)
40 {
41 	int result;
42 
43 	if (!mbi_pdev)
44 		return -ENODEV;
45 
46 	if (mcrx) {
47 		result = pci_write_config_dword(mbi_pdev, MBI_MCRX_OFFSET,
48 						mcrx);
49 		if (result < 0)
50 			goto fail_read;
51 	}
52 
53 	result = pci_write_config_dword(mbi_pdev, MBI_MCR_OFFSET, mcr);
54 	if (result < 0)
55 		goto fail_read;
56 
57 	result = pci_read_config_dword(mbi_pdev, MBI_MDR_OFFSET, mdr);
58 	if (result < 0)
59 		goto fail_read;
60 
61 	return 0;
62 
63 fail_read:
64 	dev_err(&mbi_pdev->dev, "PCI config access failed with %d\n", result);
65 	return pcibios_err_to_errno(result);
66 }
67 
iosf_mbi_pci_write_mdr(u32 mcrx,u32 mcr,u32 mdr)68 static int iosf_mbi_pci_write_mdr(u32 mcrx, u32 mcr, u32 mdr)
69 {
70 	int result;
71 
72 	if (!mbi_pdev)
73 		return -ENODEV;
74 
75 	result = pci_write_config_dword(mbi_pdev, MBI_MDR_OFFSET, mdr);
76 	if (result < 0)
77 		goto fail_write;
78 
79 	if (mcrx) {
80 		result = pci_write_config_dword(mbi_pdev, MBI_MCRX_OFFSET,
81 						mcrx);
82 		if (result < 0)
83 			goto fail_write;
84 	}
85 
86 	result = pci_write_config_dword(mbi_pdev, MBI_MCR_OFFSET, mcr);
87 	if (result < 0)
88 		goto fail_write;
89 
90 	return 0;
91 
92 fail_write:
93 	dev_err(&mbi_pdev->dev, "PCI config access failed with %d\n", result);
94 	return pcibios_err_to_errno(result);
95 }
96 
iosf_mbi_read(u8 port,u8 opcode,u32 offset,u32 * mdr)97 int iosf_mbi_read(u8 port, u8 opcode, u32 offset, u32 *mdr)
98 {
99 	u32 mcr, mcrx;
100 	unsigned long flags;
101 	int ret;
102 
103 	/* Access to the GFX unit is handled by GPU code */
104 	if (port == BT_MBI_UNIT_GFX) {
105 		WARN_ON(1);
106 		return -EPERM;
107 	}
108 
109 	mcr = iosf_mbi_form_mcr(opcode, port, offset & MBI_MASK_LO);
110 	mcrx = offset & MBI_MASK_HI;
111 
112 	spin_lock_irqsave(&iosf_mbi_lock, flags);
113 	ret = iosf_mbi_pci_read_mdr(mcrx, mcr, mdr);
114 	spin_unlock_irqrestore(&iosf_mbi_lock, flags);
115 
116 	return ret;
117 }
118 EXPORT_SYMBOL(iosf_mbi_read);
119 
iosf_mbi_write(u8 port,u8 opcode,u32 offset,u32 mdr)120 int iosf_mbi_write(u8 port, u8 opcode, u32 offset, u32 mdr)
121 {
122 	u32 mcr, mcrx;
123 	unsigned long flags;
124 	int ret;
125 
126 	/* Access to the GFX unit is handled by GPU code */
127 	if (port == BT_MBI_UNIT_GFX) {
128 		WARN_ON(1);
129 		return -EPERM;
130 	}
131 
132 	mcr = iosf_mbi_form_mcr(opcode, port, offset & MBI_MASK_LO);
133 	mcrx = offset & MBI_MASK_HI;
134 
135 	spin_lock_irqsave(&iosf_mbi_lock, flags);
136 	ret = iosf_mbi_pci_write_mdr(mcrx, mcr, mdr);
137 	spin_unlock_irqrestore(&iosf_mbi_lock, flags);
138 
139 	return ret;
140 }
141 EXPORT_SYMBOL(iosf_mbi_write);
142 
iosf_mbi_modify(u8 port,u8 opcode,u32 offset,u32 mdr,u32 mask)143 int iosf_mbi_modify(u8 port, u8 opcode, u32 offset, u32 mdr, u32 mask)
144 {
145 	u32 mcr, mcrx;
146 	u32 value;
147 	unsigned long flags;
148 	int ret;
149 
150 	/* Access to the GFX unit is handled by GPU code */
151 	if (port == BT_MBI_UNIT_GFX) {
152 		WARN_ON(1);
153 		return -EPERM;
154 	}
155 
156 	mcr = iosf_mbi_form_mcr(opcode, port, offset & MBI_MASK_LO);
157 	mcrx = offset & MBI_MASK_HI;
158 
159 	spin_lock_irqsave(&iosf_mbi_lock, flags);
160 
161 	/* Read current mdr value */
162 	ret = iosf_mbi_pci_read_mdr(mcrx, mcr & MBI_RD_MASK, &value);
163 	if (ret < 0) {
164 		spin_unlock_irqrestore(&iosf_mbi_lock, flags);
165 		return ret;
166 	}
167 
168 	/* Apply mask */
169 	value &= ~mask;
170 	mdr &= mask;
171 	value |= mdr;
172 
173 	/* Write back */
174 	ret = iosf_mbi_pci_write_mdr(mcrx, mcr | MBI_WR_MASK, value);
175 
176 	spin_unlock_irqrestore(&iosf_mbi_lock, flags);
177 
178 	return ret;
179 }
180 EXPORT_SYMBOL(iosf_mbi_modify);
181 
iosf_mbi_available(void)182 bool iosf_mbi_available(void)
183 {
184 	/* Mbi isn't hot-pluggable. No remove routine is provided */
185 	return mbi_pdev;
186 }
187 EXPORT_SYMBOL(iosf_mbi_available);
188 
189 /*
190  **************** P-Unit/kernel shared I2C bus arbitration ****************
191  *
192  * Some Bay Trail and Cherry Trail devices have the P-Unit and us (the kernel)
193  * share a single I2C bus to the PMIC. Below are helpers to arbitrate the
194  * accesses between the kernel and the P-Unit.
195  *
196  * See arch/x86/include/asm/iosf_mbi.h for kernel-doc text for each function.
197  */
198 
199 #define SEMAPHORE_TIMEOUT		500
200 #define PUNIT_SEMAPHORE_BYT		0x7
201 #define PUNIT_SEMAPHORE_CHT		0x10e
202 #define PUNIT_SEMAPHORE_BIT		BIT(0)
203 #define PUNIT_SEMAPHORE_ACQUIRE		BIT(1)
204 
205 static DEFINE_MUTEX(iosf_mbi_pmic_access_mutex);
206 static BLOCKING_NOTIFIER_HEAD(iosf_mbi_pmic_bus_access_notifier);
207 static DECLARE_WAIT_QUEUE_HEAD(iosf_mbi_pmic_access_waitq);
208 static u32 iosf_mbi_pmic_punit_access_count;
209 static u32 iosf_mbi_pmic_i2c_access_count;
210 static u32 iosf_mbi_sem_address;
211 static unsigned long iosf_mbi_sem_acquired;
212 static struct pm_qos_request iosf_mbi_pm_qos;
213 
iosf_mbi_punit_acquire(void)214 void iosf_mbi_punit_acquire(void)
215 {
216 	/* Wait for any I2C PMIC accesses from in kernel drivers to finish. */
217 	mutex_lock(&iosf_mbi_pmic_access_mutex);
218 	while (iosf_mbi_pmic_i2c_access_count != 0) {
219 		mutex_unlock(&iosf_mbi_pmic_access_mutex);
220 		wait_event(iosf_mbi_pmic_access_waitq,
221 			   iosf_mbi_pmic_i2c_access_count == 0);
222 		mutex_lock(&iosf_mbi_pmic_access_mutex);
223 	}
224 	/*
225 	 * We do not need to do anything to allow the PUNIT to safely access
226 	 * the PMIC, other then block in kernel accesses to the PMIC.
227 	 */
228 	iosf_mbi_pmic_punit_access_count++;
229 	mutex_unlock(&iosf_mbi_pmic_access_mutex);
230 }
231 EXPORT_SYMBOL(iosf_mbi_punit_acquire);
232 
iosf_mbi_punit_release(void)233 void iosf_mbi_punit_release(void)
234 {
235 	bool do_wakeup;
236 
237 	mutex_lock(&iosf_mbi_pmic_access_mutex);
238 	iosf_mbi_pmic_punit_access_count--;
239 	do_wakeup = iosf_mbi_pmic_punit_access_count == 0;
240 	mutex_unlock(&iosf_mbi_pmic_access_mutex);
241 
242 	if (do_wakeup)
243 		wake_up(&iosf_mbi_pmic_access_waitq);
244 }
245 EXPORT_SYMBOL(iosf_mbi_punit_release);
246 
iosf_mbi_get_sem(u32 * sem)247 static int iosf_mbi_get_sem(u32 *sem)
248 {
249 	int ret;
250 
251 	ret = iosf_mbi_read(BT_MBI_UNIT_PMC, MBI_REG_READ,
252 			    iosf_mbi_sem_address, sem);
253 	if (ret) {
254 		dev_err(&mbi_pdev->dev, "Error P-Unit semaphore read failed\n");
255 		return ret;
256 	}
257 
258 	*sem &= PUNIT_SEMAPHORE_BIT;
259 	return 0;
260 }
261 
iosf_mbi_reset_semaphore(void)262 static void iosf_mbi_reset_semaphore(void)
263 {
264 	if (iosf_mbi_modify(BT_MBI_UNIT_PMC, MBI_REG_READ,
265 			    iosf_mbi_sem_address, 0, PUNIT_SEMAPHORE_BIT))
266 		dev_err(&mbi_pdev->dev, "Error P-Unit semaphore reset failed\n");
267 
268 	cpu_latency_qos_update_request(&iosf_mbi_pm_qos, PM_QOS_DEFAULT_VALUE);
269 
270 	blocking_notifier_call_chain(&iosf_mbi_pmic_bus_access_notifier,
271 				     MBI_PMIC_BUS_ACCESS_END, NULL);
272 }
273 
274 /*
275  * This function blocks P-Unit accesses to the PMIC I2C bus, so that kernel
276  * I2C code, such as e.g. a fuel-gauge driver, can access it safely.
277  *
278  * This function may be called by I2C controller code while an I2C driver has
279  * already blocked P-Unit accesses because it wants them blocked over multiple
280  * i2c-transfers, for e.g. read-modify-write of an I2C client register.
281  *
282  * To allow safe PMIC i2c bus accesses this function takes the following steps:
283  *
284  * 1) Some code sends request to the P-Unit which make it access the PMIC
285  *    I2C bus. Testing has shown that the P-Unit does not check its internal
286  *    PMIC bus semaphore for these requests. Callers of these requests call
287  *    iosf_mbi_punit_acquire()/_release() around their P-Unit accesses, these
288  *    functions increase/decrease iosf_mbi_pmic_punit_access_count, so first
289  *    we wait for iosf_mbi_pmic_punit_access_count to become 0.
290  *
291  * 2) Check iosf_mbi_pmic_i2c_access_count, if access has already
292  *    been blocked by another caller, we only need to increment
293  *    iosf_mbi_pmic_i2c_access_count and we can skip the other steps.
294  *
295  * 3) Some code makes such P-Unit requests from atomic contexts where it
296  *    cannot call iosf_mbi_punit_acquire() as that may sleep.
297  *    As the second step we call a notifier chain which allows any code
298  *    needing P-Unit resources from atomic context to acquire them before
299  *    we take control over the PMIC I2C bus.
300  *
301  * 4) When CPU cores enter C6 or C7 the P-Unit needs to talk to the PMIC
302  *    if this happens while the kernel itself is accessing the PMIC I2C bus
303  *    the SoC hangs.
304  *    As the third step we call cpu_latency_qos_update_request() to disallow the
305  *    CPU to enter C6 or C7.
306  *
307  * 5) The P-Unit has a PMIC bus semaphore which we can request to stop
308  *    autonomous P-Unit tasks from accessing the PMIC I2C bus while we hold it.
309  *    As the fourth and final step we request this semaphore and wait for our
310  *    request to be acknowledged.
311  */
iosf_mbi_block_punit_i2c_access(void)312 int iosf_mbi_block_punit_i2c_access(void)
313 {
314 	unsigned long start, end;
315 	int ret = 0;
316 	u32 sem;
317 
318 	if (WARN_ON(!mbi_pdev || !iosf_mbi_sem_address))
319 		return -ENXIO;
320 
321 	mutex_lock(&iosf_mbi_pmic_access_mutex);
322 
323 	while (iosf_mbi_pmic_punit_access_count != 0) {
324 		mutex_unlock(&iosf_mbi_pmic_access_mutex);
325 		wait_event(iosf_mbi_pmic_access_waitq,
326 			   iosf_mbi_pmic_punit_access_count == 0);
327 		mutex_lock(&iosf_mbi_pmic_access_mutex);
328 	}
329 
330 	if (iosf_mbi_pmic_i2c_access_count > 0)
331 		goto success;
332 
333 	blocking_notifier_call_chain(&iosf_mbi_pmic_bus_access_notifier,
334 				     MBI_PMIC_BUS_ACCESS_BEGIN, NULL);
335 
336 	/*
337 	 * Disallow the CPU to enter C6 or C7 state, entering these states
338 	 * requires the P-Unit to talk to the PMIC and if this happens while
339 	 * we're holding the semaphore, the SoC hangs.
340 	 */
341 	cpu_latency_qos_update_request(&iosf_mbi_pm_qos, 0);
342 
343 	/* host driver writes to side band semaphore register */
344 	ret = iosf_mbi_write(BT_MBI_UNIT_PMC, MBI_REG_WRITE,
345 			     iosf_mbi_sem_address, PUNIT_SEMAPHORE_ACQUIRE);
346 	if (ret) {
347 		dev_err(&mbi_pdev->dev, "Error P-Unit semaphore request failed\n");
348 		goto error;
349 	}
350 
351 	/* host driver waits for bit 0 to be set in semaphore register */
352 	start = jiffies;
353 	end = start + msecs_to_jiffies(SEMAPHORE_TIMEOUT);
354 	do {
355 		ret = iosf_mbi_get_sem(&sem);
356 		if (!ret && sem) {
357 			iosf_mbi_sem_acquired = jiffies;
358 			dev_dbg(&mbi_pdev->dev, "P-Unit semaphore acquired after %ums\n",
359 				jiffies_to_msecs(jiffies - start));
360 			goto success;
361 		}
362 
363 		usleep_range(1000, 2000);
364 	} while (time_before(jiffies, end));
365 
366 	ret = -ETIMEDOUT;
367 	dev_err(&mbi_pdev->dev, "Error P-Unit semaphore timed out, resetting\n");
368 error:
369 	iosf_mbi_reset_semaphore();
370 	if (!iosf_mbi_get_sem(&sem))
371 		dev_err(&mbi_pdev->dev, "P-Unit semaphore: %d\n", sem);
372 success:
373 	if (!WARN_ON(ret))
374 		iosf_mbi_pmic_i2c_access_count++;
375 
376 	mutex_unlock(&iosf_mbi_pmic_access_mutex);
377 
378 	return ret;
379 }
380 EXPORT_SYMBOL(iosf_mbi_block_punit_i2c_access);
381 
iosf_mbi_unblock_punit_i2c_access(void)382 void iosf_mbi_unblock_punit_i2c_access(void)
383 {
384 	bool do_wakeup = false;
385 
386 	mutex_lock(&iosf_mbi_pmic_access_mutex);
387 	iosf_mbi_pmic_i2c_access_count--;
388 	if (iosf_mbi_pmic_i2c_access_count == 0) {
389 		iosf_mbi_reset_semaphore();
390 		dev_dbg(&mbi_pdev->dev, "punit semaphore held for %ums\n",
391 			jiffies_to_msecs(jiffies - iosf_mbi_sem_acquired));
392 		do_wakeup = true;
393 	}
394 	mutex_unlock(&iosf_mbi_pmic_access_mutex);
395 
396 	if (do_wakeup)
397 		wake_up(&iosf_mbi_pmic_access_waitq);
398 }
399 EXPORT_SYMBOL(iosf_mbi_unblock_punit_i2c_access);
400 
iosf_mbi_register_pmic_bus_access_notifier(struct notifier_block * nb)401 int iosf_mbi_register_pmic_bus_access_notifier(struct notifier_block *nb)
402 {
403 	int ret;
404 
405 	/* Wait for the bus to go inactive before registering */
406 	iosf_mbi_punit_acquire();
407 	ret = blocking_notifier_chain_register(
408 				&iosf_mbi_pmic_bus_access_notifier, nb);
409 	iosf_mbi_punit_release();
410 
411 	return ret;
412 }
413 EXPORT_SYMBOL(iosf_mbi_register_pmic_bus_access_notifier);
414 
iosf_mbi_unregister_pmic_bus_access_notifier_unlocked(struct notifier_block * nb)415 int iosf_mbi_unregister_pmic_bus_access_notifier_unlocked(
416 	struct notifier_block *nb)
417 {
418 	iosf_mbi_assert_punit_acquired();
419 
420 	return blocking_notifier_chain_unregister(
421 				&iosf_mbi_pmic_bus_access_notifier, nb);
422 }
423 EXPORT_SYMBOL(iosf_mbi_unregister_pmic_bus_access_notifier_unlocked);
424 
iosf_mbi_unregister_pmic_bus_access_notifier(struct notifier_block * nb)425 int iosf_mbi_unregister_pmic_bus_access_notifier(struct notifier_block *nb)
426 {
427 	int ret;
428 
429 	/* Wait for the bus to go inactive before unregistering */
430 	iosf_mbi_punit_acquire();
431 	ret = iosf_mbi_unregister_pmic_bus_access_notifier_unlocked(nb);
432 	iosf_mbi_punit_release();
433 
434 	return ret;
435 }
436 EXPORT_SYMBOL(iosf_mbi_unregister_pmic_bus_access_notifier);
437 
iosf_mbi_assert_punit_acquired(void)438 void iosf_mbi_assert_punit_acquired(void)
439 {
440 	WARN_ON(iosf_mbi_pmic_punit_access_count == 0);
441 }
442 EXPORT_SYMBOL(iosf_mbi_assert_punit_acquired);
443 
444 /**************** iosf_mbi debug code ****************/
445 
446 #ifdef CONFIG_IOSF_MBI_DEBUG
447 static u32	dbg_mdr;
448 static u32	dbg_mcr;
449 static u32	dbg_mcrx;
450 
mcr_get(void * data,u64 * val)451 static int mcr_get(void *data, u64 *val)
452 {
453 	*val = *(u32 *)data;
454 	return 0;
455 }
456 
mcr_set(void * data,u64 val)457 static int mcr_set(void *data, u64 val)
458 {
459 	u8 command = ((u32)val & 0xFF000000) >> 24,
460 	   port	   = ((u32)val & 0x00FF0000) >> 16,
461 	   offset  = ((u32)val & 0x0000FF00) >> 8;
462 	int err;
463 
464 	*(u32 *)data = val;
465 
466 	if (!capable(CAP_SYS_RAWIO))
467 		return -EACCES;
468 
469 	if (command & 1u)
470 		err = iosf_mbi_write(port,
471 			       command,
472 			       dbg_mcrx | offset,
473 			       dbg_mdr);
474 	else
475 		err = iosf_mbi_read(port,
476 			      command,
477 			      dbg_mcrx | offset,
478 			      &dbg_mdr);
479 
480 	return err;
481 }
482 DEFINE_SIMPLE_ATTRIBUTE(iosf_mcr_fops, mcr_get, mcr_set , "%llx\n");
483 
484 static struct dentry *iosf_dbg;
485 
iosf_sideband_debug_init(void)486 static void iosf_sideband_debug_init(void)
487 {
488 	iosf_dbg = debugfs_create_dir("iosf_sb", NULL);
489 
490 	/* mdr */
491 	debugfs_create_x32("mdr", 0660, iosf_dbg, &dbg_mdr);
492 
493 	/* mcrx */
494 	debugfs_create_x32("mcrx", 0660, iosf_dbg, &dbg_mcrx);
495 
496 	/* mcr - initiates mailbox transaction */
497 	debugfs_create_file("mcr", 0660, iosf_dbg, &dbg_mcr, &iosf_mcr_fops);
498 }
499 
iosf_debugfs_init(void)500 static void iosf_debugfs_init(void)
501 {
502 	iosf_sideband_debug_init();
503 }
504 
iosf_debugfs_remove(void)505 static void iosf_debugfs_remove(void)
506 {
507 	debugfs_remove_recursive(iosf_dbg);
508 }
509 #else
iosf_debugfs_init(void)510 static inline void iosf_debugfs_init(void) { }
iosf_debugfs_remove(void)511 static inline void iosf_debugfs_remove(void) { }
512 #endif /* CONFIG_IOSF_MBI_DEBUG */
513 
iosf_mbi_probe(struct pci_dev * pdev,const struct pci_device_id * dev_id)514 static int iosf_mbi_probe(struct pci_dev *pdev,
515 			  const struct pci_device_id *dev_id)
516 {
517 	int ret;
518 
519 	ret = pci_enable_device(pdev);
520 	if (ret < 0) {
521 		dev_err(&pdev->dev, "error: could not enable device\n");
522 		return ret;
523 	}
524 
525 	mbi_pdev = pci_dev_get(pdev);
526 	iosf_mbi_sem_address = dev_id->driver_data;
527 
528 	return 0;
529 }
530 
531 static const struct pci_device_id iosf_mbi_pci_ids[] = {
532 	{ PCI_DEVICE_DATA(INTEL, BAYTRAIL, PUNIT_SEMAPHORE_BYT) },
533 	{ PCI_DEVICE_DATA(INTEL, BRASWELL, PUNIT_SEMAPHORE_CHT) },
534 	{ PCI_DEVICE_DATA(INTEL, QUARK_X1000, 0) },
535 	{ PCI_DEVICE_DATA(INTEL, TANGIER, 0) },
536 	{ 0, },
537 };
538 MODULE_DEVICE_TABLE(pci, iosf_mbi_pci_ids);
539 
540 static struct pci_driver iosf_mbi_pci_driver = {
541 	.name		= "iosf_mbi_pci",
542 	.probe		= iosf_mbi_probe,
543 	.id_table	= iosf_mbi_pci_ids,
544 };
545 
iosf_mbi_init(void)546 static int __init iosf_mbi_init(void)
547 {
548 	iosf_debugfs_init();
549 
550 	cpu_latency_qos_add_request(&iosf_mbi_pm_qos, PM_QOS_DEFAULT_VALUE);
551 
552 	return pci_register_driver(&iosf_mbi_pci_driver);
553 }
554 
iosf_mbi_exit(void)555 static void __exit iosf_mbi_exit(void)
556 {
557 	iosf_debugfs_remove();
558 
559 	pci_unregister_driver(&iosf_mbi_pci_driver);
560 	pci_dev_put(mbi_pdev);
561 	mbi_pdev = NULL;
562 
563 	cpu_latency_qos_remove_request(&iosf_mbi_pm_qos);
564 }
565 
566 module_init(iosf_mbi_init);
567 module_exit(iosf_mbi_exit);
568 
569 MODULE_AUTHOR("David E. Box <david.e.box@linux.intel.com>");
570 MODULE_DESCRIPTION("IOSF Mailbox Interface accessor");
571 MODULE_LICENSE("GPL v2");
572