Linux Audio

Check our new training course

Linux BSP upgrade and security maintenance

Need help to get security updates for your Linux BSP?
Loading...
Note: File does not exist in v3.1.
  1// SPDX-License-Identifier: GPL-2.0-only
  2/*
  3 *  dcdbas.c: Dell Systems Management Base Driver
  4 *
  5 *  The Dell Systems Management Base Driver provides a sysfs interface for
  6 *  systems management software to perform System Management Interrupts (SMIs)
  7 *  and Host Control Actions (power cycle or power off after OS shutdown) on
  8 *  Dell systems.
  9 *
 10 *  See Documentation/driver-api/dcdbas.rst for more information.
 11 *
 12 *  Copyright (C) 1995-2006 Dell Inc.
 13 */
 14
 15#include <linux/platform_device.h>
 16#include <linux/acpi.h>
 17#include <linux/dma-mapping.h>
 18#include <linux/errno.h>
 19#include <linux/cpu.h>
 20#include <linux/gfp.h>
 21#include <linux/init.h>
 22#include <linux/io.h>
 23#include <linux/kernel.h>
 24#include <linux/mc146818rtc.h>
 25#include <linux/module.h>
 26#include <linux/reboot.h>
 27#include <linux/sched.h>
 28#include <linux/smp.h>
 29#include <linux/spinlock.h>
 30#include <linux/string.h>
 31#include <linux/types.h>
 32#include <linux/mutex.h>
 33
 34#include "dcdbas.h"
 35
 36#define DRIVER_NAME		"dcdbas"
 37#define DRIVER_VERSION		"5.6.0-3.3"
 38#define DRIVER_DESCRIPTION	"Dell Systems Management Base Driver"
 39
 40static struct platform_device *dcdbas_pdev;
 41
 42static u8 *smi_data_buf;
 43static dma_addr_t smi_data_buf_handle;
 44static unsigned long smi_data_buf_size;
 45static unsigned long max_smi_data_buf_size = MAX_SMI_DATA_BUF_SIZE;
 46static u32 smi_data_buf_phys_addr;
 47static DEFINE_MUTEX(smi_data_lock);
 48static u8 *eps_buffer;
 49
 50static unsigned int host_control_action;
 51static unsigned int host_control_smi_type;
 52static unsigned int host_control_on_shutdown;
 53
 54static bool wsmt_enabled;
 55
 56/**
 57 * smi_data_buf_free: free SMI data buffer
 58 */
 59static void smi_data_buf_free(void)
 60{
 61	if (!smi_data_buf || wsmt_enabled)
 62		return;
 63
 64	dev_dbg(&dcdbas_pdev->dev, "%s: phys: %x size: %lu\n",
 65		__func__, smi_data_buf_phys_addr, smi_data_buf_size);
 66
 67	dma_free_coherent(&dcdbas_pdev->dev, smi_data_buf_size, smi_data_buf,
 68			  smi_data_buf_handle);
 69	smi_data_buf = NULL;
 70	smi_data_buf_handle = 0;
 71	smi_data_buf_phys_addr = 0;
 72	smi_data_buf_size = 0;
 73}
 74
 75/**
 76 * smi_data_buf_realloc: grow SMI data buffer if needed
 77 */
 78static int smi_data_buf_realloc(unsigned long size)
 79{
 80	void *buf;
 81	dma_addr_t handle;
 82
 83	if (smi_data_buf_size >= size)
 84		return 0;
 85
 86	if (size > max_smi_data_buf_size)
 87		return -EINVAL;
 88
 89	/* new buffer is needed */
 90	buf = dma_alloc_coherent(&dcdbas_pdev->dev, size, &handle, GFP_KERNEL);
 91	if (!buf) {
 92		dev_dbg(&dcdbas_pdev->dev,
 93			"%s: failed to allocate memory size %lu\n",
 94			__func__, size);
 95		return -ENOMEM;
 96	}
 97	/* memory zeroed by dma_alloc_coherent */
 98
 99	if (smi_data_buf)
100		memcpy(buf, smi_data_buf, smi_data_buf_size);
101
102	/* free any existing buffer */
103	smi_data_buf_free();
104
105	/* set up new buffer for use */
106	smi_data_buf = buf;
107	smi_data_buf_handle = handle;
108	smi_data_buf_phys_addr = (u32) virt_to_phys(buf);
109	smi_data_buf_size = size;
110
111	dev_dbg(&dcdbas_pdev->dev, "%s: phys: %x size: %lu\n",
112		__func__, smi_data_buf_phys_addr, smi_data_buf_size);
113
114	return 0;
115}
116
117static ssize_t smi_data_buf_phys_addr_show(struct device *dev,
118					   struct device_attribute *attr,
119					   char *buf)
120{
121	return sprintf(buf, "%x\n", smi_data_buf_phys_addr);
122}
123
124static ssize_t smi_data_buf_size_show(struct device *dev,
125				      struct device_attribute *attr,
126				      char *buf)
127{
128	return sprintf(buf, "%lu\n", smi_data_buf_size);
129}
130
131static ssize_t smi_data_buf_size_store(struct device *dev,
132				       struct device_attribute *attr,
133				       const char *buf, size_t count)
134{
135	unsigned long buf_size;
136	ssize_t ret;
137
138	buf_size = simple_strtoul(buf, NULL, 10);
139
140	/* make sure SMI data buffer is at least buf_size */
141	mutex_lock(&smi_data_lock);
142	ret = smi_data_buf_realloc(buf_size);
143	mutex_unlock(&smi_data_lock);
144	if (ret)
145		return ret;
146
147	return count;
148}
149
150static ssize_t smi_data_read(struct file *filp, struct kobject *kobj,
151			     struct bin_attribute *bin_attr,
152			     char *buf, loff_t pos, size_t count)
153{
154	ssize_t ret;
155
156	mutex_lock(&smi_data_lock);
157	ret = memory_read_from_buffer(buf, count, &pos, smi_data_buf,
158					smi_data_buf_size);
159	mutex_unlock(&smi_data_lock);
160	return ret;
161}
162
163static ssize_t smi_data_write(struct file *filp, struct kobject *kobj,
164			      struct bin_attribute *bin_attr,
165			      char *buf, loff_t pos, size_t count)
166{
167	ssize_t ret;
168
169	if ((pos + count) > max_smi_data_buf_size)
170		return -EINVAL;
171
172	mutex_lock(&smi_data_lock);
173
174	ret = smi_data_buf_realloc(pos + count);
175	if (ret)
176		goto out;
177
178	memcpy(smi_data_buf + pos, buf, count);
179	ret = count;
180out:
181	mutex_unlock(&smi_data_lock);
182	return ret;
183}
184
185static ssize_t host_control_action_show(struct device *dev,
186					struct device_attribute *attr,
187					char *buf)
188{
189	return sprintf(buf, "%u\n", host_control_action);
190}
191
192static ssize_t host_control_action_store(struct device *dev,
193					 struct device_attribute *attr,
194					 const char *buf, size_t count)
195{
196	ssize_t ret;
197
198	/* make sure buffer is available for host control command */
199	mutex_lock(&smi_data_lock);
200	ret = smi_data_buf_realloc(sizeof(struct apm_cmd));
201	mutex_unlock(&smi_data_lock);
202	if (ret)
203		return ret;
204
205	host_control_action = simple_strtoul(buf, NULL, 10);
206	return count;
207}
208
209static ssize_t host_control_smi_type_show(struct device *dev,
210					  struct device_attribute *attr,
211					  char *buf)
212{
213	return sprintf(buf, "%u\n", host_control_smi_type);
214}
215
216static ssize_t host_control_smi_type_store(struct device *dev,
217					   struct device_attribute *attr,
218					   const char *buf, size_t count)
219{
220	host_control_smi_type = simple_strtoul(buf, NULL, 10);
221	return count;
222}
223
224static ssize_t host_control_on_shutdown_show(struct device *dev,
225					     struct device_attribute *attr,
226					     char *buf)
227{
228	return sprintf(buf, "%u\n", host_control_on_shutdown);
229}
230
231static ssize_t host_control_on_shutdown_store(struct device *dev,
232					      struct device_attribute *attr,
233					      const char *buf, size_t count)
234{
235	host_control_on_shutdown = simple_strtoul(buf, NULL, 10);
236	return count;
237}
238
239static int raise_smi(void *par)
240{
241	struct smi_cmd *smi_cmd = par;
242
243	if (smp_processor_id() != 0) {
244		dev_dbg(&dcdbas_pdev->dev, "%s: failed to get CPU 0\n",
245			__func__);
246		return -EBUSY;
247	}
248
249	/* generate SMI */
250	/* inb to force posted write through and make SMI happen now */
251	asm volatile (
252		"outb %b0,%w1\n"
253		"inb %w1"
254		: /* no output args */
255		: "a" (smi_cmd->command_code),
256		  "d" (smi_cmd->command_address),
257		  "b" (smi_cmd->ebx),
258		  "c" (smi_cmd->ecx)
259		: "memory"
260	);
261
262	return 0;
263}
264/**
265 * dcdbas_smi_request: generate SMI request
266 *
267 * Called with smi_data_lock.
268 */
269int dcdbas_smi_request(struct smi_cmd *smi_cmd)
270{
271	int ret;
272
273	if (smi_cmd->magic != SMI_CMD_MAGIC) {
274		dev_info(&dcdbas_pdev->dev, "%s: invalid magic value\n",
275			 __func__);
276		return -EBADR;
277	}
278
279	/* SMI requires CPU 0 */
280	get_online_cpus();
281	ret = smp_call_on_cpu(0, raise_smi, smi_cmd, true);
282	put_online_cpus();
283
284	return ret;
285}
286
287/**
288 * smi_request_store:
289 *
290 * The valid values are:
291 * 0: zero SMI data buffer
292 * 1: generate calling interface SMI
293 * 2: generate raw SMI
294 *
295 * User application writes smi_cmd to smi_data before telling driver
296 * to generate SMI.
297 */
298static ssize_t smi_request_store(struct device *dev,
299				 struct device_attribute *attr,
300				 const char *buf, size_t count)
301{
302	struct smi_cmd *smi_cmd;
303	unsigned long val = simple_strtoul(buf, NULL, 10);
304	ssize_t ret;
305
306	mutex_lock(&smi_data_lock);
307
308	if (smi_data_buf_size < sizeof(struct smi_cmd)) {
309		ret = -ENODEV;
310		goto out;
311	}
312	smi_cmd = (struct smi_cmd *)smi_data_buf;
313
314	switch (val) {
315	case 2:
316		/* Raw SMI */
317		ret = dcdbas_smi_request(smi_cmd);
318		if (!ret)
319			ret = count;
320		break;
321	case 1:
322		/*
323		 * Calling Interface SMI
324		 *
325		 * Provide physical address of command buffer field within
326		 * the struct smi_cmd to BIOS.
327		 *
328		 * Because the address that smi_cmd (smi_data_buf) points to
329		 * will be from memremap() of a non-memory address if WSMT
330		 * is present, we can't use virt_to_phys() on smi_cmd, so
331		 * we have to use the physical address that was saved when
332		 * the virtual address for smi_cmd was received.
333		 */
334		smi_cmd->ebx = smi_data_buf_phys_addr +
335				offsetof(struct smi_cmd, command_buffer);
336		ret = dcdbas_smi_request(smi_cmd);
337		if (!ret)
338			ret = count;
339		break;
340	case 0:
341		memset(smi_data_buf, 0, smi_data_buf_size);
342		ret = count;
343		break;
344	default:
345		ret = -EINVAL;
346		break;
347	}
348
349out:
350	mutex_unlock(&smi_data_lock);
351	return ret;
352}
353EXPORT_SYMBOL(dcdbas_smi_request);
354
355/**
356 * host_control_smi: generate host control SMI
357 *
358 * Caller must set up the host control command in smi_data_buf.
359 */
360static int host_control_smi(void)
361{
362	struct apm_cmd *apm_cmd;
363	u8 *data;
364	unsigned long flags;
365	u32 num_ticks;
366	s8 cmd_status;
367	u8 index;
368
369	apm_cmd = (struct apm_cmd *)smi_data_buf;
370	apm_cmd->status = ESM_STATUS_CMD_UNSUCCESSFUL;
371
372	switch (host_control_smi_type) {
373	case HC_SMITYPE_TYPE1:
374		spin_lock_irqsave(&rtc_lock, flags);
375		/* write SMI data buffer physical address */
376		data = (u8 *)&smi_data_buf_phys_addr;
377		for (index = PE1300_CMOS_CMD_STRUCT_PTR;
378		     index < (PE1300_CMOS_CMD_STRUCT_PTR + 4);
379		     index++, data++) {
380			outb(index,
381			     (CMOS_BASE_PORT + CMOS_PAGE2_INDEX_PORT_PIIX4));
382			outb(*data,
383			     (CMOS_BASE_PORT + CMOS_PAGE2_DATA_PORT_PIIX4));
384		}
385
386		/* first set status to -1 as called by spec */
387		cmd_status = ESM_STATUS_CMD_UNSUCCESSFUL;
388		outb((u8) cmd_status, PCAT_APM_STATUS_PORT);
389
390		/* generate SMM call */
391		outb(ESM_APM_CMD, PCAT_APM_CONTROL_PORT);
392		spin_unlock_irqrestore(&rtc_lock, flags);
393
394		/* wait a few to see if it executed */
395		num_ticks = TIMEOUT_USEC_SHORT_SEMA_BLOCKING;
396		while ((cmd_status = inb(PCAT_APM_STATUS_PORT))
397		       == ESM_STATUS_CMD_UNSUCCESSFUL) {
398			num_ticks--;
399			if (num_ticks == EXPIRED_TIMER)
400				return -ETIME;
401		}
402		break;
403
404	case HC_SMITYPE_TYPE2:
405	case HC_SMITYPE_TYPE3:
406		spin_lock_irqsave(&rtc_lock, flags);
407		/* write SMI data buffer physical address */
408		data = (u8 *)&smi_data_buf_phys_addr;
409		for (index = PE1400_CMOS_CMD_STRUCT_PTR;
410		     index < (PE1400_CMOS_CMD_STRUCT_PTR + 4);
411		     index++, data++) {
412			outb(index, (CMOS_BASE_PORT + CMOS_PAGE1_INDEX_PORT));
413			outb(*data, (CMOS_BASE_PORT + CMOS_PAGE1_DATA_PORT));
414		}
415
416		/* generate SMM call */
417		if (host_control_smi_type == HC_SMITYPE_TYPE3)
418			outb(ESM_APM_CMD, PCAT_APM_CONTROL_PORT);
419		else
420			outb(ESM_APM_CMD, PE1400_APM_CONTROL_PORT);
421
422		/* restore RTC index pointer since it was written to above */
423		CMOS_READ(RTC_REG_C);
424		spin_unlock_irqrestore(&rtc_lock, flags);
425
426		/* read control port back to serialize write */
427		cmd_status = inb(PE1400_APM_CONTROL_PORT);
428
429		/* wait a few to see if it executed */
430		num_ticks = TIMEOUT_USEC_SHORT_SEMA_BLOCKING;
431		while (apm_cmd->status == ESM_STATUS_CMD_UNSUCCESSFUL) {
432			num_ticks--;
433			if (num_ticks == EXPIRED_TIMER)
434				return -ETIME;
435		}
436		break;
437
438	default:
439		dev_dbg(&dcdbas_pdev->dev, "%s: invalid SMI type %u\n",
440			__func__, host_control_smi_type);
441		return -ENOSYS;
442	}
443
444	return 0;
445}
446
447/**
448 * dcdbas_host_control: initiate host control
449 *
450 * This function is called by the driver after the system has
451 * finished shutting down if the user application specified a
452 * host control action to perform on shutdown.  It is safe to
453 * use smi_data_buf at this point because the system has finished
454 * shutting down and no userspace apps are running.
455 */
456static void dcdbas_host_control(void)
457{
458	struct apm_cmd *apm_cmd;
459	u8 action;
460
461	if (host_control_action == HC_ACTION_NONE)
462		return;
463
464	action = host_control_action;
465	host_control_action = HC_ACTION_NONE;
466
467	if (!smi_data_buf) {
468		dev_dbg(&dcdbas_pdev->dev, "%s: no SMI buffer\n", __func__);
469		return;
470	}
471
472	if (smi_data_buf_size < sizeof(struct apm_cmd)) {
473		dev_dbg(&dcdbas_pdev->dev, "%s: SMI buffer too small\n",
474			__func__);
475		return;
476	}
477
478	apm_cmd = (struct apm_cmd *)smi_data_buf;
479
480	/* power off takes precedence */
481	if (action & HC_ACTION_HOST_CONTROL_POWEROFF) {
482		apm_cmd->command = ESM_APM_POWER_CYCLE;
483		apm_cmd->reserved = 0;
484		*((s16 *)&apm_cmd->parameters.shortreq.parm[0]) = (s16) 0;
485		host_control_smi();
486	} else if (action & HC_ACTION_HOST_CONTROL_POWERCYCLE) {
487		apm_cmd->command = ESM_APM_POWER_CYCLE;
488		apm_cmd->reserved = 0;
489		*((s16 *)&apm_cmd->parameters.shortreq.parm[0]) = (s16) 20;
490		host_control_smi();
491	}
492}
493
494/* WSMT */
495
496static u8 checksum(u8 *buffer, u8 length)
497{
498	u8 sum = 0;
499	u8 *end = buffer + length;
500
501	while (buffer < end)
502		sum += *buffer++;
503	return sum;
504}
505
506static inline struct smm_eps_table *check_eps_table(u8 *addr)
507{
508	struct smm_eps_table *eps = (struct smm_eps_table *)addr;
509
510	if (strncmp(eps->smm_comm_buff_anchor, SMM_EPS_SIG, 4) != 0)
511		return NULL;
512
513	if (checksum(addr, eps->length) != 0)
514		return NULL;
515
516	return eps;
517}
518
519static int dcdbas_check_wsmt(void)
520{
521	struct acpi_table_wsmt *wsmt = NULL;
522	struct smm_eps_table *eps = NULL;
523	u64 remap_size;
524	u8 *addr;
525
526	acpi_get_table(ACPI_SIG_WSMT, 0, (struct acpi_table_header **)&wsmt);
527	if (!wsmt)
528		return 0;
529
530	/* Check if WSMT ACPI table shows that protection is enabled */
531	if (!(wsmt->protection_flags & ACPI_WSMT_FIXED_COMM_BUFFERS) ||
532	    !(wsmt->protection_flags & ACPI_WSMT_COMM_BUFFER_NESTED_PTR_PROTECTION))
533		return 0;
534
535	/* Scan for EPS (entry point structure) */
536	for (addr = (u8 *)__va(0xf0000);
537	     addr < (u8 *)__va(0x100000 - sizeof(struct smm_eps_table));
538	     addr += 16) {
539		eps = check_eps_table(addr);
540		if (eps)
541			break;
542	}
543
544	if (!eps) {
545		dev_dbg(&dcdbas_pdev->dev, "found WSMT, but no EPS found\n");
546		return -ENODEV;
547	}
548
549	/*
550	 * Get physical address of buffer and map to virtual address.
551	 * Table gives size in 4K pages, regardless of actual system page size.
552	 */
553	if (upper_32_bits(eps->smm_comm_buff_addr + 8)) {
554		dev_warn(&dcdbas_pdev->dev, "found WSMT, but EPS buffer address is above 4GB\n");
555		return -EINVAL;
556	}
557	/*
558	 * Limit remap size to MAX_SMI_DATA_BUF_SIZE + 8 (since the first 8
559	 * bytes are used for a semaphore, not the data buffer itself).
560	 */
561	remap_size = eps->num_of_4k_pages * PAGE_SIZE;
562	if (remap_size > MAX_SMI_DATA_BUF_SIZE + 8)
563		remap_size = MAX_SMI_DATA_BUF_SIZE + 8;
564	eps_buffer = memremap(eps->smm_comm_buff_addr, remap_size, MEMREMAP_WB);
565	if (!eps_buffer) {
566		dev_warn(&dcdbas_pdev->dev, "found WSMT, but failed to map EPS buffer\n");
567		return -ENOMEM;
568	}
569
570	/* First 8 bytes is for a semaphore, not part of the smi_data_buf */
571	smi_data_buf_phys_addr = eps->smm_comm_buff_addr + 8;
572	smi_data_buf = eps_buffer + 8;
573	smi_data_buf_size = remap_size - 8;
574	max_smi_data_buf_size = smi_data_buf_size;
575	wsmt_enabled = true;
576	dev_info(&dcdbas_pdev->dev,
577		 "WSMT found, using firmware-provided SMI buffer.\n");
578	return 1;
579}
580
581/**
582 * dcdbas_reboot_notify: handle reboot notification for host control
583 */
584static int dcdbas_reboot_notify(struct notifier_block *nb, unsigned long code,
585				void *unused)
586{
587	switch (code) {
588	case SYS_DOWN:
589	case SYS_HALT:
590	case SYS_POWER_OFF:
591		if (host_control_on_shutdown) {
592			/* firmware is going to perform host control action */
593			printk(KERN_WARNING "Please wait for shutdown "
594			       "action to complete...\n");
595			dcdbas_host_control();
596		}
597		break;
598	}
599
600	return NOTIFY_DONE;
601}
602
603static struct notifier_block dcdbas_reboot_nb = {
604	.notifier_call = dcdbas_reboot_notify,
605	.next = NULL,
606	.priority = INT_MIN
607};
608
609static DCDBAS_BIN_ATTR_RW(smi_data);
610
611static struct bin_attribute *dcdbas_bin_attrs[] = {
612	&bin_attr_smi_data,
613	NULL
614};
615
616static DCDBAS_DEV_ATTR_RW(smi_data_buf_size);
617static DCDBAS_DEV_ATTR_RO(smi_data_buf_phys_addr);
618static DCDBAS_DEV_ATTR_WO(smi_request);
619static DCDBAS_DEV_ATTR_RW(host_control_action);
620static DCDBAS_DEV_ATTR_RW(host_control_smi_type);
621static DCDBAS_DEV_ATTR_RW(host_control_on_shutdown);
622
623static struct attribute *dcdbas_dev_attrs[] = {
624	&dev_attr_smi_data_buf_size.attr,
625	&dev_attr_smi_data_buf_phys_addr.attr,
626	&dev_attr_smi_request.attr,
627	&dev_attr_host_control_action.attr,
628	&dev_attr_host_control_smi_type.attr,
629	&dev_attr_host_control_on_shutdown.attr,
630	NULL
631};
632
633static const struct attribute_group dcdbas_attr_group = {
634	.attrs = dcdbas_dev_attrs,
635	.bin_attrs = dcdbas_bin_attrs,
636};
637
638static int dcdbas_probe(struct platform_device *dev)
639{
640	int error;
641
642	host_control_action = HC_ACTION_NONE;
643	host_control_smi_type = HC_SMITYPE_NONE;
644
645	dcdbas_pdev = dev;
646
647	/* Check if ACPI WSMT table specifies protected SMI buffer address */
648	error = dcdbas_check_wsmt();
649	if (error < 0)
650		return error;
651
652	/*
653	 * BIOS SMI calls require buffer addresses be in 32-bit address space.
654	 * This is done by setting the DMA mask below.
655	 */
656	error = dma_set_coherent_mask(&dcdbas_pdev->dev, DMA_BIT_MASK(32));
657	if (error)
658		return error;
659
660	error = sysfs_create_group(&dev->dev.kobj, &dcdbas_attr_group);
661	if (error)
662		return error;
663
664	register_reboot_notifier(&dcdbas_reboot_nb);
665
666	dev_info(&dev->dev, "%s (version %s)\n",
667		 DRIVER_DESCRIPTION, DRIVER_VERSION);
668
669	return 0;
670}
671
672static int dcdbas_remove(struct platform_device *dev)
673{
674	unregister_reboot_notifier(&dcdbas_reboot_nb);
675	sysfs_remove_group(&dev->dev.kobj, &dcdbas_attr_group);
676
677	return 0;
678}
679
680static struct platform_driver dcdbas_driver = {
681	.driver		= {
682		.name	= DRIVER_NAME,
683	},
684	.probe		= dcdbas_probe,
685	.remove		= dcdbas_remove,
686};
687
688static const struct platform_device_info dcdbas_dev_info __initconst = {
689	.name		= DRIVER_NAME,
690	.id		= -1,
691	.dma_mask	= DMA_BIT_MASK(32),
692};
693
694static struct platform_device *dcdbas_pdev_reg;
695
696/**
697 * dcdbas_init: initialize driver
698 */
699static int __init dcdbas_init(void)
700{
701	int error;
702
703	error = platform_driver_register(&dcdbas_driver);
704	if (error)
705		return error;
706
707	dcdbas_pdev_reg = platform_device_register_full(&dcdbas_dev_info);
708	if (IS_ERR(dcdbas_pdev_reg)) {
709		error = PTR_ERR(dcdbas_pdev_reg);
710		goto err_unregister_driver;
711	}
712
713	return 0;
714
715 err_unregister_driver:
716	platform_driver_unregister(&dcdbas_driver);
717	return error;
718}
719
720/**
721 * dcdbas_exit: perform driver cleanup
722 */
723static void __exit dcdbas_exit(void)
724{
725	/*
726	 * make sure functions that use dcdbas_pdev are called
727	 * before platform_device_unregister
728	 */
729	unregister_reboot_notifier(&dcdbas_reboot_nb);
730
731	/*
732	 * We have to free the buffer here instead of dcdbas_remove
733	 * because only in module exit function we can be sure that
734	 * all sysfs attributes belonging to this module have been
735	 * released.
736	 */
737	if (dcdbas_pdev)
738		smi_data_buf_free();
739	if (eps_buffer)
740		memunmap(eps_buffer);
741	platform_device_unregister(dcdbas_pdev_reg);
742	platform_driver_unregister(&dcdbas_driver);
743}
744
745subsys_initcall_sync(dcdbas_init);
746module_exit(dcdbas_exit);
747
748MODULE_DESCRIPTION(DRIVER_DESCRIPTION " (version " DRIVER_VERSION ")");
749MODULE_VERSION(DRIVER_VERSION);
750MODULE_AUTHOR("Dell Inc.");
751MODULE_LICENSE("GPL");
752/* Any System or BIOS claiming to be by Dell */
753MODULE_ALIAS("dmi:*:[bs]vnD[Ee][Ll][Ll]*:*");