aboutsummaryrefslogblamecommitdiffstats
path: root/drivers/hwmon/sch56xx-common.c
blob: ce52fc57d41d70cf8bb119e9e3a2d3756e294615 (plain) (tree)
1
2
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
                                                                            
                                                                            

























                                                                             





                             

                           





                                                                              









                                                                              
                                                        
 
                                  



                                    






















                                                                            

                                            








                                                                              
















































































































































































                                                                              






















































































































































































































































































































































































































































































                                                                               














                                                                    


                                  































































































                                                                              
/***************************************************************************
 *   Copyright (C) 2010-2012 Hans de Goede <hdegoede@redhat.com>           *
 *                                                                         *
 *   This program is free software; you can redistribute it and/or modify  *
 *   it under the terms of the GNU General Public License as published by  *
 *   the Free Software Foundation; either version 2 of the License, or     *
 *   (at your option) any later version.                                   *
 *                                                                         *
 *   This program is distributed in the hope that it will be useful,       *
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of        *
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         *
 *   GNU General Public License for more details.                          *
 *                                                                         *
 *   You should have received a copy of the GNU General Public License     *
 *   along with this program; if not, write to the                         *
 *   Free Software Foundation, Inc.,                                       *
 *   59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.             *
 ***************************************************************************/

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/module.h>
#include <linux/init.h>
#include <linux/platform_device.h>
#include <linux/err.h>
#include <linux/io.h>
#include <linux/acpi.h>
#include <linux/delay.h>
#include <linux/fs.h>
#include <linux/watchdog.h>
#include <linux/miscdevice.h>
#include <linux/uaccess.h>
#include <linux/kref.h>
#include <linux/slab.h>
#include "sch56xx-common.h"

/* Insmod parameters */
static int nowayout = WATCHDOG_NOWAYOUT;
module_param(nowayout, int, 0);
MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
	__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");

#define SIO_SCH56XX_LD_EM	0x0C	/* Embedded uController Logical Dev */
#define SIO_UNLOCK_KEY		0x55	/* Key to enable Super-I/O */
#define SIO_LOCK_KEY		0xAA	/* Key to disable Super-I/O */

#define SIO_REG_LDSEL		0x07	/* Logical device select */
#define SIO_REG_DEVID		0x20	/* Device ID */
#define SIO_REG_ENABLE		0x30	/* Logical device enable */
#define SIO_REG_ADDR		0x66	/* Logical device address (2 bytes) */

#define SIO_SCH5627_ID		0xC6	/* Chipset ID */
#define SIO_SCH5636_ID		0xC7	/* Chipset ID */

#define REGION_LENGTH		10

#define SCH56XX_CMD_READ	0x02
#define SCH56XX_CMD_WRITE	0x03

/* Watchdog registers */
#define SCH56XX_REG_WDOG_PRESET		0x58B
#define SCH56XX_REG_WDOG_CONTROL	0x58C
#define SCH56XX_WDOG_TIME_BASE_SEC	0x01
#define SCH56XX_REG_WDOG_OUTPUT_ENABLE	0x58E
#define SCH56XX_WDOG_OUTPUT_ENABLE	0x02

struct sch56xx_watchdog_data {
	u16 addr;
	u32 revision;
	struct mutex *io_lock;
	struct mutex watchdog_lock;
	struct list_head list; /* member of the watchdog_data_list */
	struct kref kref;
	struct miscdevice watchdog_miscdev;
	unsigned long watchdog_is_open;
	char watchdog_name[10]; /* must be unique to avoid sysfs conflict */
	char watchdog_expect_close;
	u8 watchdog_preset;
	u8 watchdog_control;
	u8 watchdog_output_enable;
};

static struct platform_device *sch56xx_pdev;

/*
 * Somewhat ugly :( global data pointer list with all sch56xx devices, so that
 * we can find our device data as when using misc_register there is no other
 * method to get to ones device data from the open fop.
 */
static LIST_HEAD(watchdog_data_list);
/* Note this lock not only protect list access, but also data.kref access */
static DEFINE_MUTEX(watchdog_data_mutex);

/* Super I/O functions */
static inline int superio_inb(int base, int reg)
{
	outb(reg, base);
	return inb(base + 1);
}

static inline int superio_enter(int base)
{
	/* Don't step on other drivers' I/O space by accident */
	if (!request_muxed_region(base, 2, "sch56xx")) {
		pr_err("I/O address 0x%04x already in use\n", base);
		return -EBUSY;
	}

	outb(SIO_UNLOCK_KEY, base);

	return 0;
}

static inline void superio_select(int base, int ld)
{
	outb(SIO_REG_LDSEL, base);
	outb(ld, base + 1);
}

static inline void superio_exit(int base)
{
	outb(SIO_LOCK_KEY, base);
	release_region(base, 2);
}

static int sch56xx_send_cmd(u16 addr, u8 cmd, u16 reg, u8 v)
{
	u8 val;
	int i;
	/*
	 * According to SMSC for the commands we use the maximum time for
	 * the EM to respond is 15 ms, but testing shows in practice it
	 * responds within 15-32 reads, so we first busy poll, and if
	 * that fails sleep a bit and try again until we are way past
	 * the 15 ms maximum response time.
	 */
	const int max_busy_polls = 64;
	const int max_lazy_polls = 32;

	/* (Optional) Write-Clear the EC to Host Mailbox Register */
	val = inb(addr + 1);
	outb(val, addr + 1);

	/* Set Mailbox Address Pointer to first location in Region 1 */
	outb(0x00, addr + 2);
	outb(0x80, addr + 3);

	/* Write Request Packet Header */
	outb(cmd, addr + 4); /* VREG Access Type read:0x02 write:0x03 */
	outb(0x01, addr + 5); /* # of Entries: 1 Byte (8-bit) */
	outb(0x04, addr + 2); /* Mailbox AP to first data entry loc. */

	/* Write Value field */
	if (cmd == SCH56XX_CMD_WRITE)
		outb(v, addr + 4);

	/* Write Address field */
	outb(reg & 0xff, addr + 6);
	outb(reg >> 8, addr + 7);

	/* Execute the Random Access Command */
	outb(0x01, addr); /* Write 01h to the Host-to-EC register */

	/* EM Interface Polling "Algorithm" */
	for (i = 0; i < max_busy_polls + max_lazy_polls; i++) {
		if (i >= max_busy_polls)
			msleep(1);
		/* Read Interrupt source Register */
		val = inb(addr + 8);
		/* Write Clear the interrupt source bits */
		if (val)
			outb(val, addr + 8);
		/* Command Completed ? */
		if (val & 0x01)
			break;
	}
	if (i == max_busy_polls + max_lazy_polls) {
		pr_err("Max retries exceeded reading virtual "
		       "register 0x%04hx (%d)\n", reg, 1);
		return -EIO;
	}

	/*
	 * According to SMSC we may need to retry this, but sofar I've always
	 * seen this succeed in 1 try.
	 */
	for (i = 0; i < max_busy_polls; i++) {
		/* Read EC-to-Host Register */
		val = inb(addr + 1);
		/* Command Completed ? */
		if (val == 0x01)
			break;

		if (i == 0)
			pr_warn("EC reports: 0x%02x reading virtual register "
				"0x%04hx\n", (unsigned int)val, reg);
	}
	if (i == max_busy_polls) {
		pr_err("Max retries exceeded reading virtual "
		       "register 0x%04hx (%d)\n", reg, 2);
		return -EIO;
	}

	/*
	 * According to the SMSC app note we should now do:
	 *
	 * Set Mailbox Address Pointer to first location in Region 1 *
	 * outb(0x00, addr + 2);
	 * outb(0x80, addr + 3);
	 *
	 * But if we do that things don't work, so let's not.
	 */

	/* Read Value field */
	if (cmd == SCH56XX_CMD_READ)
		return inb(addr + 4);

	return 0;
}

int sch56xx_read_virtual_reg(u16 addr, u16 reg)
{
	return sch56xx_send_cmd(addr, SCH56XX_CMD_READ, reg, 0);
}
EXPORT_SYMBOL(sch56xx_read_virtual_reg);

int sch56xx_write_virtual_reg(u16 addr, u16 reg, u8 val)
{
	return sch56xx_send_cmd(addr, SCH56XX_CMD_WRITE, reg, val);
}
EXPORT_SYMBOL(sch56xx_write_virtual_reg);

int sch56xx_read_virtual_reg16(u16 addr, u16 reg)
{
	int lsb, msb;

	/* Read LSB first, this will cause the matching MSB to be latched */
	lsb = sch56xx_read_virtual_reg(addr, reg);
	if (lsb < 0)
		return lsb;

	msb = sch56xx_read_virtual_reg(addr, reg + 1);
	if (msb < 0)
		return msb;

	return lsb | (msb << 8);
}
EXPORT_SYMBOL(sch56xx_read_virtual_reg16);

int sch56xx_read_virtual_reg12(u16 addr, u16 msb_reg, u16 lsn_reg,
			       int high_nibble)
{
	int msb, lsn;

	/* Read MSB first, this will cause the matching LSN to be latched */
	msb = sch56xx_read_virtual_reg(addr, msb_reg);
	if (msb < 0)
		return msb;

	lsn = sch56xx_read_virtual_reg(addr, lsn_reg);
	if (lsn < 0)
		return lsn;

	if (high_nibble)
		return (msb << 4) | (lsn >> 4);
	else
		return (msb << 4) | (lsn & 0x0f);
}
EXPORT_SYMBOL(sch56xx_read_virtual_reg12);

/*
 * Watchdog routines
 */

/*
 * Release our data struct when the platform device has been released *and*
 * all references to our watchdog device are released.
 */
static void sch56xx_watchdog_release_resources(struct kref *r)
{
	struct sch56xx_watchdog_data *data =
		container_of(r, struct sch56xx_watchdog_data, kref);
	kfree(data);
}

static int watchdog_set_timeout(struct sch56xx_watchdog_data *data,
				int timeout)
{
	int ret, resolution;
	u8 control;

	/* 1 second or 60 second resolution? */
	if (timeout <= 255)
		resolution = 1;
	else
		resolution = 60;

	if (timeout < resolution || timeout > (resolution * 255))
		return -EINVAL;

	mutex_lock(&data->watchdog_lock);
	if (!data->addr) {
		ret = -ENODEV;
		goto leave;
	}

	if (resolution == 1)
		control = data->watchdog_control | SCH56XX_WDOG_TIME_BASE_SEC;
	else
		control = data->watchdog_control & ~SCH56XX_WDOG_TIME_BASE_SEC;

	if (data->watchdog_control != control) {
		mutex_lock(data->io_lock);
		ret = sch56xx_write_virtual_reg(data->addr,
						SCH56XX_REG_WDOG_CONTROL,
						control);
		mutex_unlock(data->io_lock);
		if (ret)
			goto leave;

		data->watchdog_control = control;
	}

	/*
	 * Remember new timeout value, but do not write as that (re)starts
	 * the watchdog countdown.
	 */
	data->watchdog_preset = DIV_ROUND_UP(timeout, resolution);

	ret = data->watchdog_preset * resolution;
leave:
	mutex_unlock(&data->watchdog_lock);
	return ret;
}

static int watchdog_get_timeout(struct sch56xx_watchdog_data *data)
{
	int timeout;

	mutex_lock(&data->watchdog_lock);
	if (data->watchdog_control & SCH56XX_WDOG_TIME_BASE_SEC)
		timeout = data->watchdog_preset;
	else
		timeout = data->watchdog_preset * 60;
	mutex_unlock(&data->watchdog_lock);

	return timeout;
}

static int watchdog_start(struct sch56xx_watchdog_data *data)
{
	int ret;
	u8 val;

	mutex_lock(&data->watchdog_lock);
	if (!data->addr) {
		ret = -ENODEV;
		goto leave_unlock_watchdog;
	}

	/*
	 * The sch56xx's watchdog cannot really be started / stopped
	 * it is always running, but we can avoid the timer expiring
	 * from causing a system reset by clearing the output enable bit.
	 *
	 * The sch56xx's watchdog will set the watchdog event bit, bit 0
	 * of the second interrupt source register (at base-address + 9),
	 * when the timer expires.
	 *
	 * This will only cause a system reset if the 0-1 flank happens when
	 * output enable is true. Setting output enable after the flank will
	 * not cause a reset, nor will the timer expiring a second time.
	 * This means we must clear the watchdog event bit in case it is set.
	 *
	 * The timer may still be running (after a recent watchdog_stop) and
	 * mere milliseconds away from expiring, so the timer must be reset
	 * first!
	 */

	mutex_lock(data->io_lock);

	/* 1. Reset the watchdog countdown counter */
	ret = sch56xx_write_virtual_reg(data->addr, SCH56XX_REG_WDOG_PRESET,
					data->watchdog_preset);
	if (ret)
		goto leave;

	/* 2. Enable output (if not already enabled) */
	if (!(data->watchdog_output_enable & SCH56XX_WDOG_OUTPUT_ENABLE)) {
		val = data->watchdog_output_enable |
		      SCH56XX_WDOG_OUTPUT_ENABLE;
		ret = sch56xx_write_virtual_reg(data->addr,
						SCH56XX_REG_WDOG_OUTPUT_ENABLE,
						val);
		if (ret)
			goto leave;

		data->watchdog_output_enable = val;
	}

	/* 3. Clear the watchdog event bit if set */
	val = inb(data->addr + 9);
	if (val & 0x01)
		outb(0x01, data->addr + 9);

leave:
	mutex_unlock(data->io_lock);
leave_unlock_watchdog:
	mutex_unlock(&data->watchdog_lock);
	return ret;
}

static int watchdog_trigger(struct sch56xx_watchdog_data *data)
{
	int ret;

	mutex_lock(&data->watchdog_lock);
	if (!data->addr) {
		ret = -ENODEV;
		goto leave;
	}

	/* Reset the watchdog countdown counter */
	mutex_lock(data->io_lock);
	ret = sch56xx_write_virtual_reg(data->addr, SCH56XX_REG_WDOG_PRESET,
					data->watchdog_preset);
	mutex_unlock(data->io_lock);
leave:
	mutex_unlock(&data->watchdog_lock);
	return ret;
}

static int watchdog_stop_unlocked(struct sch56xx_watchdog_data *data)
{
	int ret = 0;
	u8 val;

	if (!data->addr)
		return -ENODEV;

	if (data->watchdog_output_enable & SCH56XX_WDOG_OUTPUT_ENABLE) {
		val = data->watchdog_output_enable &
		      ~SCH56XX_WDOG_OUTPUT_ENABLE;
		mutex_lock(data->io_lock);
		ret = sch56xx_write_virtual_reg(data->addr,
						SCH56XX_REG_WDOG_OUTPUT_ENABLE,
						val);
		mutex_unlock(data->io_lock);
		if (ret)
			return ret;

		data->watchdog_output_enable = val;
	}

	return ret;
}

static int watchdog_stop(struct sch56xx_watchdog_data *data)
{
	int ret;

	mutex_lock(&data->watchdog_lock);
	ret = watchdog_stop_unlocked(data);
	mutex_unlock(&data->watchdog_lock);

	return ret;
}

static int watchdog_release(struct inode *inode, struct file *filp)
{
	struct sch56xx_watchdog_data *data = filp->private_data;

	if (data->watchdog_expect_close) {
		watchdog_stop(data);
		data->watchdog_expect_close = 0;
	} else {
		watchdog_trigger(data);
		pr_crit("unexpected close, not stopping watchdog!\n");
	}

	clear_bit(0, &data->watchdog_is_open);

	mutex_lock(&watchdog_data_mutex);
	kref_put(&data->kref, sch56xx_watchdog_release_resources);
	mutex_unlock(&watchdog_data_mutex);

	return 0;
}

static int watchdog_open(struct inode *inode, struct file *filp)
{
	struct sch56xx_watchdog_data *pos, *data = NULL;
	int ret, watchdog_is_open;

	/*
	 * We get called from drivers/char/misc.c with misc_mtx hold, and we
	 * call misc_register() from sch56xx_watchdog_probe() with
	 * watchdog_data_mutex hold, as misc_register() takes the misc_mtx
	 * lock, this is a possible deadlock, so we use mutex_trylock here.
	 */
	if (!mutex_trylock(&watchdog_data_mutex))
		return -ERESTARTSYS;
	list_for_each_entry(pos, &watchdog_data_list, list) {
		if (pos->watchdog_miscdev.minor == iminor(inode)) {
			data = pos;
			break;
		}
	}
	/* Note we can never not have found data, so we don't check for this */
	watchdog_is_open = test_and_set_bit(0, &data->watchdog_is_open);
	if (!watchdog_is_open)
		kref_get(&data->kref);
	mutex_unlock(&watchdog_data_mutex);

	if (watchdog_is_open)
		return -EBUSY;

	filp->private_data = data;

	/* Start the watchdog */
	ret = watchdog_start(data);
	if (ret) {
		watchdog_release(inode, filp);
		return ret;
	}

	return nonseekable_open(inode, filp);
}

static ssize_t watchdog_write(struct file *filp, const char __user *buf,
	size_t count, loff_t *offset)
{
	int ret;
	struct sch56xx_watchdog_data *data = filp->private_data;

	if (count) {
		if (!nowayout) {
			size_t i;

			/* Clear it in case it was set with a previous write */
			data->watchdog_expect_close = 0;

			for (i = 0; i != count; i++) {
				char c;
				if (get_user(c, buf + i))
					return -EFAULT;
				if (c == 'V')
					data->watchdog_expect_close = 1;
			}
		}
		ret = watchdog_trigger(data);
		if (ret)
			return ret;
	}
	return count;
}

static long watchdog_ioctl(struct file *filp, unsigned int cmd,
			   unsigned long arg)
{
	struct watchdog_info ident = {
		.options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT,
		.identity = "sch56xx watchdog"
	};
	int i, ret = 0;
	struct sch56xx_watchdog_data *data = filp->private_data;

	switch (cmd) {
	case WDIOC_GETSUPPORT:
		ident.firmware_version = data->revision;
		if (!nowayout)
			ident.options |= WDIOF_MAGICCLOSE;
		if (copy_to_user((void __user *)arg, &ident, sizeof(ident)))
			ret = -EFAULT;
		break;

	case WDIOC_GETSTATUS:
	case WDIOC_GETBOOTSTATUS:
		ret = put_user(0, (int __user *)arg);
		break;

	case WDIOC_KEEPALIVE:
		ret = watchdog_trigger(data);
		break;

	case WDIOC_GETTIMEOUT:
		i = watchdog_get_timeout(data);
		ret = put_user(i, (int __user *)arg);
		break;

	case WDIOC_SETTIMEOUT:
		if (get_user(i, (int __user *)arg)) {
			ret = -EFAULT;
			break;
		}
		ret = watchdog_set_timeout(data, i);
		if (ret >= 0)
			ret = put_user(ret, (int __user *)arg);
		break;

	case WDIOC_SETOPTIONS:
		if (get_user(i, (int __user *)arg)) {
			ret = -EFAULT;
			break;
		}

		if (i & WDIOS_DISABLECARD)
			ret = watchdog_stop(data);
		else if (i & WDIOS_ENABLECARD)
			ret = watchdog_trigger(data);
		else
			ret = -EINVAL;
		break;

	default:
		ret = -ENOTTY;
	}
	return ret;
}

static const struct file_operations watchdog_fops = {
	.owner = THIS_MODULE,
	.llseek = no_llseek,
	.open = watchdog_open,
	.release = watchdog_release,
	.write = watchdog_write,
	.unlocked_ioctl = watchdog_ioctl,
};

struct sch56xx_watchdog_data *sch56xx_watchdog_register(
	u16 addr, u32 revision, struct mutex *io_lock, int check_enabled)
{
	struct sch56xx_watchdog_data *data;
	int i, err, control, output_enable;
	const int watchdog_minors[] = { WATCHDOG_MINOR, 212, 213, 214, 215 };

	/* Cache the watchdog registers */
	mutex_lock(io_lock);
	control =
		sch56xx_read_virtual_reg(addr, SCH56XX_REG_WDOG_CONTROL);
	output_enable =
		sch56xx_read_virtual_reg(addr, SCH56XX_REG_WDOG_OUTPUT_ENABLE);
	mutex_unlock(io_lock);

	if (control < 0)
		return NULL;
	if (output_enable < 0)
		return NULL;
	if (check_enabled && !(output_enable & SCH56XX_WDOG_OUTPUT_ENABLE)) {
		pr_warn("Watchdog not enabled by BIOS, not registering\n");
		return NULL;
	}

	data = kzalloc(sizeof(struct sch56xx_watchdog_data), GFP_KERNEL);
	if (!data)
		return NULL;

	data->addr = addr;
	data->revision = revision;
	data->io_lock = io_lock;
	data->watchdog_control = control;
	data->watchdog_output_enable = output_enable;
	mutex_init(&data->watchdog_lock);
	INIT_LIST_HEAD(&data->list);
	kref_init(&data->kref);

	err = watchdog_set_timeout(data, 60);
	if (err < 0)
		goto error;

	/*
	 * We take the data_mutex lock early so that watchdog_open() cannot
	 * run when misc_register() has completed, but we've not yet added
	 * our data to the watchdog_data_list.
	 */
	mutex_lock(&watchdog_data_mutex);
	for (i = 0; i < ARRAY_SIZE(watchdog_minors); i++) {
		/* Register our watchdog part */
		snprintf(data->watchdog_name, sizeof(data->watchdog_name),
			"watchdog%c", (i == 0) ? '\0' : ('0' + i));
		data->watchdog_miscdev.name = data->watchdog_name;
		data->watchdog_miscdev.fops = &watchdog_fops;
		data->watchdog_miscdev.minor = watchdog_minors[i];
		err = misc_register(&data->watchdog_miscdev);
		if (err == -EBUSY)
			continue;
		if (err)
			break;

		list_add(&data->list, &watchdog_data_list);
		pr_info("Registered /dev/%s chardev major 10, minor: %d\n",
			data->watchdog_name, watchdog_minors[i]);
		break;
	}
	mutex_unlock(&watchdog_data_mutex);

	if (err) {
		pr_err("Registering watchdog chardev: %d\n", err);
		goto error;
	}
	if (i == ARRAY_SIZE(watchdog_minors)) {
		pr_warn("Couldn't register watchdog (no free minor)\n");
		goto error;
	}

	return data;

error:
	kfree(data);
	return NULL;
}
EXPORT_SYMBOL(sch56xx_watchdog_register);

void sch56xx_watchdog_unregister(struct sch56xx_watchdog_data *data)
{
	mutex_lock(&watchdog_data_mutex);
	misc_deregister(&data->watchdog_miscdev);
	list_del(&data->list);
	mutex_unlock(&watchdog_data_mutex);

	mutex_lock(&data->watchdog_lock);
	if (data->watchdog_is_open) {
		pr_warn("platform device unregistered with watchdog "
			"open! Stopping watchdog.\n");
		watchdog_stop_unlocked(data);
	}
	/* Tell the wdog start/stop/trigger functions our dev is gone */
	data->addr = 0;
	data->io_lock = NULL;
	mutex_unlock(&data->watchdog_lock);

	mutex_lock(&watchdog_data_mutex);
	kref_put(&data->kref, sch56xx_watchdog_release_resources);
	mutex_unlock(&watchdog_data_mutex);
}
EXPORT_SYMBOL(sch56xx_watchdog_unregister);

/*
 * platform dev find, add and remove functions
 */

static int __init sch56xx_find(int sioaddr, unsigned short *address,
			       const char **name)
{
	u8 devid;
	int err;

	err = superio_enter(sioaddr);
	if (err)
		return err;

	devid = superio_inb(sioaddr, SIO_REG_DEVID);
	switch (devid) {
	case SIO_SCH5627_ID:
		*name = "sch5627";
		break;
	case SIO_SCH5636_ID:
		*name = "sch5636";
		break;
	default:
		pr_debug("Unsupported device id: 0x%02x\n",
			 (unsigned int)devid);
		err = -ENODEV;
		goto exit;
	}

	superio_select(sioaddr, SIO_SCH56XX_LD_EM);

	if (!(superio_inb(sioaddr, SIO_REG_ENABLE) & 0x01)) {
		pr_warn("Device not activated\n");
		err = -ENODEV;
		goto exit;
	}

	/*
	 * Warning the order of the low / high byte is the other way around
	 * as on most other superio devices!!
	 */
	*address = superio_inb(sioaddr, SIO_REG_ADDR) |
		   superio_inb(sioaddr, SIO_REG_ADDR + 1) << 8;
	if (*address == 0) {
		pr_warn("Base address not set\n");
		err = -ENODEV;
		goto exit;
	}

exit:
	superio_exit(sioaddr);
	return err;
}

static int __init sch56xx_device_add(unsigned short address, const char *name)
{
	struct resource res = {
		.start	= address,
		.end	= address + REGION_LENGTH - 1,
		.flags	= IORESOURCE_IO,
	};
	int err;

	sch56xx_pdev = platform_device_alloc(name, address);
	if (!sch56xx_pdev)
		return -ENOMEM;

	res.name = sch56xx_pdev->name;
	err = acpi_check_resource_conflict(&res);
	if (err)
		goto exit_device_put;

	err = platform_device_add_resources(sch56xx_pdev, &res, 1);
	if (err) {
		pr_err("Device resource addition failed\n");
		goto exit_device_put;
	}

	err = platform_device_add(sch56xx_pdev);
	if (err) {
		pr_err("Device addition failed\n");
		goto exit_device_put;
	}

	return 0;

exit_device_put:
	platform_device_put(sch56xx_pdev);

	return err;
}

static int __init sch56xx_init(void)
{
	int err;
	unsigned short address;
	const char *name;

	err = sch56xx_find(0x4e, &address, &name);
	if (err)
		err = sch56xx_find(0x2e, &address, &name);
	if (err)
		return err;

	return sch56xx_device_add(address, name);
}

static void __exit sch56xx_exit(void)
{
	platform_device_unregister(sch56xx_pdev);
}

MODULE_DESCRIPTION("SMSC SCH56xx Hardware Monitoring Common Code");
MODULE_AUTHOR("Hans de Goede <hdegoede@redhat.com>");
MODULE_LICENSE("GPL");

module_init(sch56xx_init);
module_exit(sch56xx_exit);