siox-core.c 21.3 KB
Newer Older
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35
// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (C) 2015-2017 Pengutronix, Uwe Kleine-König <kernel@pengutronix.de>
 */
#include <linux/kernel.h>
#include <linux/device.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/sysfs.h>

#include "siox.h"

/*
 * The lowest bit in the SIOX status word signals if the in-device watchdog is
 * ok. If the bit is set, the device is functional.
 *
 * On writing the watchdog timer is reset when this bit toggles.
 */
#define SIOX_STATUS_WDG			0x01

/*
 * Bits 1 to 3 of the status word read as the bitwise negation of what was
 * clocked in before. The value clocked in is changed in each cycle and so
 * allows to detect transmit/receive problems.
 */
#define SIOX_STATUS_COUNTER		0x0e

/*
 * Each Siox-Device has a 4 bit type number that is neither 0 nor 15. This is
 * available in the upper nibble of the read status.
 *
 * On write these bits are DC.
 */
#define SIOX_STATUS_TYPE		0xf0

U
Uwe Kleine-König 已提交
36 37 38
#define CREATE_TRACE_POINTS
#include <trace/events/siox.h>

39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131
static bool siox_is_registered;

static void siox_master_lock(struct siox_master *smaster)
{
	mutex_lock(&smaster->lock);
}

static void siox_master_unlock(struct siox_master *smaster)
{
	mutex_unlock(&smaster->lock);
}

static inline u8 siox_status_clean(u8 status_read, u8 status_written)
{
	/*
	 * bits 3:1 of status sample the respective bit in the status
	 * byte written in the previous cycle but inverted. So if you wrote the
	 * status word as 0xa before (counter = 0b101), it is expected to get
	 * back the counter bits as 0b010.
	 *
	 * So given the last status written this function toggles the there
	 * unset counter bits in the read value such that the counter bits in
	 * the return value are all zero iff the bits were read as expected to
	 * simplify error detection.
	 */

	return status_read ^ (~status_written & 0xe);
}

static bool siox_device_counter_error(struct siox_device *sdevice,
				      u8 status_clean)
{
	return (status_clean & SIOX_STATUS_COUNTER) != 0;
}

static bool siox_device_type_error(struct siox_device *sdevice, u8 status_clean)
{
	u8 statustype = (status_clean & SIOX_STATUS_TYPE) >> 4;

	/*
	 * If the device knows which value the type bits should have, check
	 * against this value otherwise just rule out the invalid values 0b0000
	 * and 0b1111.
	 */
	if (sdevice->statustype) {
		if (statustype != sdevice->statustype)
			return true;
	} else {
		switch (statustype) {
		case 0:
		case 0xf:
			return true;
		}
	}

	return false;
}

static bool siox_device_wdg_error(struct siox_device *sdevice, u8 status_clean)
{
	return (status_clean & SIOX_STATUS_WDG) == 0;
}

/*
 * If there is a type or counter error the device is called "unsynced".
 */
bool siox_device_synced(struct siox_device *sdevice)
{
	if (siox_device_type_error(sdevice, sdevice->status_read_clean))
		return false;

	return !siox_device_counter_error(sdevice, sdevice->status_read_clean);

}
EXPORT_SYMBOL_GPL(siox_device_synced);

/*
 * A device is called "connected" if it is synced and the watchdog is not
 * asserted.
 */
bool siox_device_connected(struct siox_device *sdevice)
{
	if (!siox_device_synced(sdevice))
		return false;

	return !siox_device_wdg_error(sdevice, sdevice->status_read_clean);
}
EXPORT_SYMBOL_GPL(siox_device_connected);

static void siox_poll(struct siox_master *smaster)
{
	struct siox_device *sdevice;
	size_t i = smaster->setbuf_len;
U
Uwe Kleine-König 已提交
132
	unsigned int devno = 0;
133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178
	int unsync_error = 0;

	smaster->last_poll = jiffies;

	/*
	 * The counter bits change in each second cycle, the watchdog bit
	 * toggles each time.
	 * The counter bits hold values from [0, 6]. 7 would be possible
	 * theoretically but the protocol designer considered that a bad idea
	 * for reasons unknown today. (Maybe that's because then the status read
	 * back has only zeros in the counter bits then which might be confused
	 * with a stuck-at-0 error. But for the same reason (with s/0/1/) 0
	 * could be skipped.)
	 */
	if (++smaster->status > 0x0d)
		smaster->status = 0;

	memset(smaster->buf, 0, smaster->setbuf_len);

	/* prepare data pushed out to devices in buf[0..setbuf_len) */
	list_for_each_entry(sdevice, &smaster->devices, node) {
		struct siox_driver *sdriver =
			to_siox_driver(sdevice->dev.driver);
		sdevice->status_written = smaster->status;

		i -= sdevice->inbytes;

		/*
		 * If the device or a previous one is unsynced, don't pet the
		 * watchdog. This is done to ensure that the device is kept in
		 * reset when something is wrong.
		 */
		if (!siox_device_synced(sdevice))
			unsync_error = 1;

		if (sdriver && !unsync_error)
			sdriver->set_data(sdevice, sdevice->status_written,
					  &smaster->buf[i + 1]);
		else
			/*
			 * Don't trigger watchdog if there is no driver or a
			 * sync problem
			 */
			sdevice->status_written &= ~SIOX_STATUS_WDG;

		smaster->buf[i] = sdevice->status_written;
U
Uwe Kleine-König 已提交
179 180 181 182

		trace_siox_set_data(smaster, sdevice, devno, i);

		devno++;
183 184 185 186 187 188 189 190 191
	}

	smaster->pushpull(smaster, smaster->setbuf_len, smaster->buf,
			  smaster->getbuf_len,
			  smaster->buf + smaster->setbuf_len);

	unsync_error = 0;

	/* interpret data pulled in from devices in buf[setbuf_len..] */
U
Uwe Kleine-König 已提交
192
	devno = 0;
193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266
	i = smaster->setbuf_len;
	list_for_each_entry(sdevice, &smaster->devices, node) {
		struct siox_driver *sdriver =
			to_siox_driver(sdevice->dev.driver);
		u8 status = smaster->buf[i + sdevice->outbytes - 1];
		u8 status_clean;
		u8 prev_status_clean = sdevice->status_read_clean;
		bool synced = true;
		bool connected = true;

		if (!siox_device_synced(sdevice))
			unsync_error = 1;

		/*
		 * If the watchdog bit wasn't toggled in this cycle, report the
		 * watchdog as active to give a consistent view for drivers and
		 * sysfs consumers.
		 */
		if (!sdriver || unsync_error)
			status &= ~SIOX_STATUS_WDG;

		status_clean =
			siox_status_clean(status,
					  sdevice->status_written_lastcycle);

		/* Check counter bits */
		if (siox_device_counter_error(sdevice, status_clean)) {
			bool prev_counter_error;

			synced = false;

			/* only report a new error if the last cycle was ok */
			prev_counter_error =
				siox_device_counter_error(sdevice,
							  prev_status_clean);
			if (!prev_counter_error) {
				sdevice->status_errors++;
				sysfs_notify_dirent(sdevice->status_errors_kn);
			}
		}

		/* Check type bits */
		if (siox_device_type_error(sdevice, status_clean))
			synced = false;

		/* If the device is unsynced report the watchdog as active */
		if (!synced) {
			status &= ~SIOX_STATUS_WDG;
			status_clean &= ~SIOX_STATUS_WDG;
		}

		if (siox_device_wdg_error(sdevice, status_clean))
			connected = false;

		/* The watchdog state changed just now */
		if ((status_clean ^ prev_status_clean) & SIOX_STATUS_WDG) {
			sysfs_notify_dirent(sdevice->watchdog_kn);

			if (siox_device_wdg_error(sdevice, status_clean)) {
				struct kernfs_node *wd_errs =
					sdevice->watchdog_errors_kn;

				sdevice->watchdog_errors++;
				sysfs_notify_dirent(wd_errs);
			}
		}

		if (connected != sdevice->connected)
			sysfs_notify_dirent(sdevice->connected_kn);

		sdevice->status_read_clean = status_clean;
		sdevice->status_written_lastcycle = sdevice->status_written;
		sdevice->connected = connected;

U
Uwe Kleine-König 已提交
267 268
		trace_siox_get_data(smaster, sdevice, devno, status_clean, i);

269 270 271 272
		/* only give data read to driver if the device is connected */
		if (sdriver && connected)
			sdriver->get_data(sdevice, &smaster->buf[i]);

U
Uwe Kleine-König 已提交
273
		devno++;
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
		i += sdevice->outbytes;
	}
}

static int siox_poll_thread(void *data)
{
	struct siox_master *smaster = data;
	signed long timeout = 0;

	get_device(&smaster->dev);

	for (;;) {
		if (kthread_should_stop()) {
			put_device(&smaster->dev);
			return 0;
		}

		siox_master_lock(smaster);

		if (smaster->active) {
			unsigned long next_poll =
				smaster->last_poll + smaster->poll_interval;
			if (time_is_before_eq_jiffies(next_poll))
				siox_poll(smaster);

			timeout = smaster->poll_interval -
				(jiffies - smaster->last_poll);
		} else {
			timeout = MAX_SCHEDULE_TIMEOUT;
		}

		/*
		 * Set the task to idle while holding the lock. This makes sure
		 * that we don't sleep too long when the bus is reenabled before
		 * schedule_timeout is reached.
		 */
		if (timeout > 0)
			set_current_state(TASK_IDLE);

		siox_master_unlock(smaster);

		if (timeout > 0)
			schedule_timeout(timeout);

		/*
		 * I'm not clear if/why it is important to set the state to
		 * RUNNING again, but it fixes a "do not call blocking ops when
		 * !TASK_RUNNING;"-warning.
		 */
		set_current_state(TASK_RUNNING);
	}
}

static int __siox_start(struct siox_master *smaster)
{
	if (!(smaster->setbuf_len + smaster->getbuf_len))
		return -ENODEV;

	if (!smaster->buf)
		return -ENOMEM;

	if (smaster->active)
		return 0;

	smaster->active = 1;
	wake_up_process(smaster->poll_thread);

	return 1;
}

static int siox_start(struct siox_master *smaster)
{
	int ret;

	siox_master_lock(smaster);
	ret = __siox_start(smaster);
	siox_master_unlock(smaster);

	return ret;
}

static int __siox_stop(struct siox_master *smaster)
{
	if (smaster->active) {
		struct siox_device *sdevice;

		smaster->active = 0;

		list_for_each_entry(sdevice, &smaster->devices, node) {
			if (sdevice->connected)
				sysfs_notify_dirent(sdevice->connected_kn);
			sdevice->connected = false;
		}

		return 1;
	}
	return 0;
}

static int siox_stop(struct siox_master *smaster)
{
	int ret;

	siox_master_lock(smaster);
	ret = __siox_stop(smaster);
	siox_master_unlock(smaster);

	return ret;
}

static ssize_t type_show(struct device *dev,
			 struct device_attribute *attr, char *buf)
{
	struct siox_device *sdev = to_siox_device(dev);

	return sprintf(buf, "%s\n", sdev->type);
}

static DEVICE_ATTR_RO(type);

static ssize_t inbytes_show(struct device *dev,
			    struct device_attribute *attr, char *buf)
{
	struct siox_device *sdev = to_siox_device(dev);

	return sprintf(buf, "%zu\n", sdev->inbytes);
}

static DEVICE_ATTR_RO(inbytes);

static ssize_t outbytes_show(struct device *dev,
			     struct device_attribute *attr, char *buf)
{
	struct siox_device *sdev = to_siox_device(dev);

	return sprintf(buf, "%zu\n", sdev->outbytes);
}

static DEVICE_ATTR_RO(outbytes);

static ssize_t status_errors_show(struct device *dev,
				  struct device_attribute *attr, char *buf)
{
	struct siox_device *sdev = to_siox_device(dev);
	unsigned int status_errors;

	siox_master_lock(sdev->smaster);

	status_errors = sdev->status_errors;

	siox_master_unlock(sdev->smaster);

	return sprintf(buf, "%u\n", status_errors);
}

static DEVICE_ATTR_RO(status_errors);

static ssize_t connected_show(struct device *dev,
			      struct device_attribute *attr, char *buf)
{
	struct siox_device *sdev = to_siox_device(dev);
	bool connected;

	siox_master_lock(sdev->smaster);

	connected = sdev->connected;

	siox_master_unlock(sdev->smaster);

	return sprintf(buf, "%u\n", connected);
}

static DEVICE_ATTR_RO(connected);

static ssize_t watchdog_show(struct device *dev,
			     struct device_attribute *attr, char *buf)
{
	struct siox_device *sdev = to_siox_device(dev);
	u8 status;

	siox_master_lock(sdev->smaster);

	status = sdev->status_read_clean;

	siox_master_unlock(sdev->smaster);

	return sprintf(buf, "%d\n", status & SIOX_STATUS_WDG);
}

static DEVICE_ATTR_RO(watchdog);

static ssize_t watchdog_errors_show(struct device *dev,
				    struct device_attribute *attr, char *buf)
{
	struct siox_device *sdev = to_siox_device(dev);
	unsigned int watchdog_errors;

	siox_master_lock(sdev->smaster);

	watchdog_errors = sdev->watchdog_errors;

	siox_master_unlock(sdev->smaster);

	return sprintf(buf, "%u\n", watchdog_errors);
}

static DEVICE_ATTR_RO(watchdog_errors);

static struct attribute *siox_device_attrs[] = {
	&dev_attr_type.attr,
	&dev_attr_inbytes.attr,
	&dev_attr_outbytes.attr,
	&dev_attr_status_errors.attr,
	&dev_attr_connected.attr,
	&dev_attr_watchdog.attr,
	&dev_attr_watchdog_errors.attr,
	NULL
};
ATTRIBUTE_GROUPS(siox_device);

static void siox_device_release(struct device *dev)
{
	struct siox_device *sdevice = to_siox_device(dev);

	kfree(sdevice);
}

static struct device_type siox_device_type = {
	.groups = siox_device_groups,
	.release = siox_device_release,
};

static int siox_match(struct device *dev, struct device_driver *drv)
{
	if (dev->type != &siox_device_type)
		return 0;

	/* up to now there is only a single driver so keeping this simple */
	return 1;
}

static struct bus_type siox_bus_type = {
	.name = "siox",
	.match = siox_match,
};

static int siox_driver_probe(struct device *dev)
{
	struct siox_driver *sdriver = to_siox_driver(dev->driver);
	struct siox_device *sdevice = to_siox_device(dev);
	int ret;

	ret = sdriver->probe(sdevice);
	return ret;
}

static int siox_driver_remove(struct device *dev)
{
	struct siox_driver *sdriver =
		container_of(dev->driver, struct siox_driver, driver);
	struct siox_device *sdevice = to_siox_device(dev);
	int ret;

	ret = sdriver->remove(sdevice);
	return ret;
}

static void siox_driver_shutdown(struct device *dev)
{
	struct siox_driver *sdriver =
		container_of(dev->driver, struct siox_driver, driver);
	struct siox_device *sdevice = to_siox_device(dev);

	sdriver->shutdown(sdevice);
}

static ssize_t active_show(struct device *dev,
			   struct device_attribute *attr, char *buf)
{
	struct siox_master *smaster = to_siox_master(dev);

	return sprintf(buf, "%d\n", smaster->active);
}

static ssize_t active_store(struct device *dev,
			    struct device_attribute *attr,
			    const char *buf, size_t count)
{
	struct siox_master *smaster = to_siox_master(dev);
	int ret;
	int active;

	ret = kstrtoint(buf, 0, &active);
	if (ret < 0)
		return ret;

	if (active)
		ret = siox_start(smaster);
	else
		ret = siox_stop(smaster);

	if (ret < 0)
		return ret;

	return count;
}

static DEVICE_ATTR_RW(active);

static struct siox_device *siox_device_add(struct siox_master *smaster,
					   const char *type, size_t inbytes,
					   size_t outbytes, u8 statustype);

static ssize_t device_add_store(struct device *dev,
				struct device_attribute *attr,
				const char *buf, size_t count)
{
	struct siox_master *smaster = to_siox_master(dev);
	int ret;
	char type[20] = "";
	size_t inbytes = 0, outbytes = 0;
	u8 statustype = 0;

597
	ret = sscanf(buf, "%19s %zu %zu %hhu", type, &inbytes,
598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821 822 823 824 825 826 827 828 829 830 831 832 833 834 835 836 837 838 839 840 841 842 843 844 845 846 847 848 849 850 851 852 853 854 855 856 857 858 859 860 861 862 863 864 865 866 867 868 869 870 871 872 873 874 875 876 877 878 879 880 881 882 883 884 885 886 887 888 889 890 891 892 893 894 895 896 897 898 899 900 901 902 903 904 905 906 907 908 909 910 911 912 913 914 915 916 917 918 919 920 921 922 923 924 925 926 927 928 929 930 931 932 933 934
		     &outbytes, &statustype);
	if (ret != 3 && ret != 4)
		return -EINVAL;

	if (strcmp(type, "siox-12x8") || inbytes != 2 || outbytes != 4)
		return -EINVAL;

	siox_device_add(smaster, "siox-12x8", inbytes, outbytes, statustype);

	return count;
}

static DEVICE_ATTR_WO(device_add);

static void siox_device_remove(struct siox_master *smaster);

static ssize_t device_remove_store(struct device *dev,
				   struct device_attribute *attr,
				   const char *buf, size_t count)
{
	struct siox_master *smaster = to_siox_master(dev);

	/* XXX? require to write <type> <inbytes> <outbytes> */
	siox_device_remove(smaster);

	return count;
}

static DEVICE_ATTR_WO(device_remove);

static ssize_t poll_interval_ns_show(struct device *dev,
				     struct device_attribute *attr, char *buf)
{
	struct siox_master *smaster = to_siox_master(dev);

	return sprintf(buf, "%lld\n", jiffies_to_nsecs(smaster->poll_interval));
}

static ssize_t poll_interval_ns_store(struct device *dev,
				      struct device_attribute *attr,
				      const char *buf, size_t count)
{
	struct siox_master *smaster = to_siox_master(dev);
	int ret;
	u64 val;

	ret = kstrtou64(buf, 0, &val);
	if (ret < 0)
		return ret;

	siox_master_lock(smaster);

	smaster->poll_interval = nsecs_to_jiffies(val);

	siox_master_unlock(smaster);

	return count;
}

static DEVICE_ATTR_RW(poll_interval_ns);

static struct attribute *siox_master_attrs[] = {
	&dev_attr_active.attr,
	&dev_attr_device_add.attr,
	&dev_attr_device_remove.attr,
	&dev_attr_poll_interval_ns.attr,
	NULL
};
ATTRIBUTE_GROUPS(siox_master);

static void siox_master_release(struct device *dev)
{
	struct siox_master *smaster = to_siox_master(dev);

	kfree(smaster);
}

static struct device_type siox_master_type = {
	.groups = siox_master_groups,
	.release = siox_master_release,
};

struct siox_master *siox_master_alloc(struct device *dev,
				      size_t size)
{
	struct siox_master *smaster;

	if (!dev)
		return NULL;

	smaster = kzalloc(sizeof(*smaster) + size, GFP_KERNEL);
	if (!smaster)
		return NULL;

	device_initialize(&smaster->dev);

	smaster->busno = -1;
	smaster->dev.bus = &siox_bus_type;
	smaster->dev.type = &siox_master_type;
	smaster->dev.parent = dev;
	smaster->poll_interval = DIV_ROUND_UP(HZ, 40);

	dev_set_drvdata(&smaster->dev, &smaster[1]);

	return smaster;
}
EXPORT_SYMBOL_GPL(siox_master_alloc);

int siox_master_register(struct siox_master *smaster)
{
	int ret;

	if (!siox_is_registered)
		return -EPROBE_DEFER;

	if (!smaster->pushpull)
		return -EINVAL;

	dev_set_name(&smaster->dev, "siox-%d", smaster->busno);

	smaster->last_poll = jiffies;
	smaster->poll_thread = kthread_create(siox_poll_thread, smaster,
					      "siox-%d", smaster->busno);
	if (IS_ERR(smaster->poll_thread)) {
		smaster->active = 0;
		return PTR_ERR(smaster->poll_thread);
	}

	mutex_init(&smaster->lock);
	INIT_LIST_HEAD(&smaster->devices);

	ret = device_add(&smaster->dev);
	if (ret)
		kthread_stop(smaster->poll_thread);

	return ret;
}
EXPORT_SYMBOL_GPL(siox_master_register);

void siox_master_unregister(struct siox_master *smaster)
{
	/* remove device */
	device_del(&smaster->dev);

	siox_master_lock(smaster);

	__siox_stop(smaster);

	while (smaster->num_devices) {
		struct siox_device *sdevice;

		sdevice = container_of(smaster->devices.prev,
				       struct siox_device, node);
		list_del(&sdevice->node);
		smaster->num_devices--;

		siox_master_unlock(smaster);

		device_unregister(&sdevice->dev);

		siox_master_lock(smaster);
	}

	siox_master_unlock(smaster);

	put_device(&smaster->dev);
}
EXPORT_SYMBOL_GPL(siox_master_unregister);

static struct siox_device *siox_device_add(struct siox_master *smaster,
					   const char *type, size_t inbytes,
					   size_t outbytes, u8 statustype)
{
	struct siox_device *sdevice;
	int ret;
	size_t buf_len;

	sdevice = kzalloc(sizeof(*sdevice), GFP_KERNEL);
	if (!sdevice)
		return ERR_PTR(-ENOMEM);

	sdevice->type = type;
	sdevice->inbytes = inbytes;
	sdevice->outbytes = outbytes;
	sdevice->statustype = statustype;

	sdevice->smaster = smaster;
	sdevice->dev.parent = &smaster->dev;
	sdevice->dev.bus = &siox_bus_type;
	sdevice->dev.type = &siox_device_type;

	siox_master_lock(smaster);

	dev_set_name(&sdevice->dev, "siox-%d-%d",
		     smaster->busno, smaster->num_devices);

	buf_len = smaster->setbuf_len + inbytes +
		smaster->getbuf_len + outbytes;
	if (smaster->buf_len < buf_len) {
		u8 *buf = krealloc(smaster->buf, buf_len, GFP_KERNEL);

		if (!buf) {
			dev_err(&smaster->dev,
				"failed to realloc buffer to %zu\n", buf_len);
			ret = -ENOMEM;
			goto err_buf_alloc;
		}

		smaster->buf_len = buf_len;
		smaster->buf = buf;
	}

	ret = device_register(&sdevice->dev);
	if (ret) {
		dev_err(&smaster->dev, "failed to register device: %d\n", ret);

		goto err_device_register;
	}

	smaster->num_devices++;
	list_add_tail(&sdevice->node, &smaster->devices);

	smaster->setbuf_len += sdevice->inbytes;
	smaster->getbuf_len += sdevice->outbytes;

	sdevice->status_errors_kn = sysfs_get_dirent(sdevice->dev.kobj.sd,
						     "status_errors");
	sdevice->watchdog_kn = sysfs_get_dirent(sdevice->dev.kobj.sd,
						"watchdog");
	sdevice->watchdog_errors_kn = sysfs_get_dirent(sdevice->dev.kobj.sd,
						       "watchdog_errors");
	sdevice->connected_kn = sysfs_get_dirent(sdevice->dev.kobj.sd,
						 "connected");

	siox_master_unlock(smaster);

	return sdevice;

err_device_register:
	/* don't care to make the buffer smaller again */

err_buf_alloc:
	siox_master_unlock(smaster);

	kfree(sdevice);

	return ERR_PTR(ret);
}

static void siox_device_remove(struct siox_master *smaster)
{
	struct siox_device *sdevice;

	siox_master_lock(smaster);

	if (!smaster->num_devices) {
		siox_master_unlock(smaster);
		return;
	}

	sdevice = container_of(smaster->devices.prev, struct siox_device, node);
	list_del(&sdevice->node);
	smaster->num_devices--;

	smaster->setbuf_len -= sdevice->inbytes;
	smaster->getbuf_len -= sdevice->outbytes;

	if (!smaster->num_devices)
		__siox_stop(smaster);

	siox_master_unlock(smaster);

	/*
	 * This must be done without holding the master lock because we're
	 * called from device_remove_store which also holds a sysfs mutex.
	 * device_unregister tries to aquire the same lock.
	 */
	device_unregister(&sdevice->dev);
}

int __siox_driver_register(struct siox_driver *sdriver, struct module *owner)
{
	int ret;

	if (unlikely(!siox_is_registered))
		return -EPROBE_DEFER;

	if (!sdriver->set_data && !sdriver->get_data) {
		pr_err("Driver %s doesn't provide needed callbacks\n",
		       sdriver->driver.name);
		return -EINVAL;
	}

	sdriver->driver.owner = owner;
	sdriver->driver.bus = &siox_bus_type;

	if (sdriver->probe)
		sdriver->driver.probe = siox_driver_probe;
	if (sdriver->remove)
		sdriver->driver.remove = siox_driver_remove;
	if (sdriver->shutdown)
		sdriver->driver.shutdown = siox_driver_shutdown;

	ret = driver_register(&sdriver->driver);
	if (ret)
		pr_err("Failed to register siox driver %s (%d)\n",
		       sdriver->driver.name, ret);

	return ret;
}
EXPORT_SYMBOL_GPL(__siox_driver_register);

static int __init siox_init(void)
{
	int ret;

	ret = bus_register(&siox_bus_type);
	if (ret) {
		pr_err("Registration of SIOX bus type failed: %d\n", ret);
		return ret;
	}

	siox_is_registered = true;

	return 0;
}
subsys_initcall(siox_init);

static void __exit siox_exit(void)
{
	bus_unregister(&siox_bus_type);
}
module_exit(siox_exit);

MODULE_AUTHOR("Uwe Kleine-Koenig <u.kleine-koenig@pengutronix.de>");
MODULE_DESCRIPTION("Eckelmann SIOX driver core");
MODULE_LICENSE("GPL v2");