1// SPDX-License-Identifier: GPL-2.0
2/*
3 *  bus driver for ccwgroup
4 *
5 *  Copyright IBM Corp. 2002, 2012
6 *
7 *  Author(s): Arnd Bergmann (arndb@de.ibm.com)
8 *	       Cornelia Huck (cornelia.huck@de.ibm.com)
9 */
10#include <linux/module.h>
11#include <linux/errno.h>
12#include <linux/slab.h>
13#include <linux/list.h>
14#include <linux/device.h>
15#include <linux/init.h>
16#include <linux/ctype.h>
17#include <linux/dcache.h>
18
19#include <asm/cio.h>
20#include <asm/ccwdev.h>
21#include <asm/ccwgroup.h>
22
23#include "device.h"
24
25#define CCW_BUS_ID_SIZE		10
26
27/* In Linux 2.4, we had a channel device layer called "chandev"
28 * that did all sorts of obscure stuff for networking devices.
29 * This is another driver that serves as a replacement for just
30 * one of its functions, namely the translation of single subchannels
31 * to devices that use multiple subchannels.
32 */
33
34static struct bus_type ccwgroup_bus_type;
35
36static void __ccwgroup_remove_symlinks(struct ccwgroup_device *gdev)
37{
38	int i;
39	char str[16];
40
41	for (i = 0; i < gdev->count; i++) {
42		sprintf(str, "cdev%d", i);
43		sysfs_remove_link(&gdev->dev.kobj, str);
44		sysfs_remove_link(&gdev->cdev[i]->dev.kobj, "group_device");
45	}
46}
47
48/*
49 * Remove references from ccw devices to ccw group device and from
50 * ccw group device to ccw devices.
51 */
52static void __ccwgroup_remove_cdev_refs(struct ccwgroup_device *gdev)
53{
54	struct ccw_device *cdev;
55	int i;
56
57	for (i = 0; i < gdev->count; i++) {
58		cdev = gdev->cdev[i];
59		if (!cdev)
60			continue;
61		spin_lock_irq(cdev->ccwlock);
62		dev_set_drvdata(&cdev->dev, NULL);
63		spin_unlock_irq(cdev->ccwlock);
64		gdev->cdev[i] = NULL;
65		put_device(&cdev->dev);
66	}
67}
68
69/**
70 * ccwgroup_set_online() - enable a ccwgroup device
71 * @gdev: target ccwgroup device
72 *
73 * This function attempts to put the ccwgroup device into the online state.
74 * Returns:
75 *  %0 on success and a negative error value on failure.
76 */
77int ccwgroup_set_online(struct ccwgroup_device *gdev)
78{
79	struct ccwgroup_driver *gdrv = to_ccwgroupdrv(gdev->dev.driver);
80	int ret = -EINVAL;
81
82	if (atomic_cmpxchg(&gdev->onoff, 0, 1) != 0)
83		return -EAGAIN;
84	if (gdev->state == CCWGROUP_ONLINE)
85		goto out;
86	if (gdrv->set_online)
87		ret = gdrv->set_online(gdev);
88	if (ret)
89		goto out;
90
91	gdev->state = CCWGROUP_ONLINE;
92out:
93	atomic_set(&gdev->onoff, 0);
94	return ret;
95}
96EXPORT_SYMBOL(ccwgroup_set_online);
97
98/**
99 * ccwgroup_set_offline() - disable a ccwgroup device
100 * @gdev: target ccwgroup device
101 *
102 * This function attempts to put the ccwgroup device into the offline state.
103 * Returns:
104 *  %0 on success and a negative error value on failure.
105 */
106int ccwgroup_set_offline(struct ccwgroup_device *gdev)
107{
108	struct ccwgroup_driver *gdrv = to_ccwgroupdrv(gdev->dev.driver);
109	int ret = -EINVAL;
110
111	if (atomic_cmpxchg(&gdev->onoff, 0, 1) != 0)
112		return -EAGAIN;
113	if (gdev->state == CCWGROUP_OFFLINE)
114		goto out;
115	if (gdrv->set_offline)
116		ret = gdrv->set_offline(gdev);
117	if (ret)
118		goto out;
119
120	gdev->state = CCWGROUP_OFFLINE;
121out:
122	atomic_set(&gdev->onoff, 0);
123	return ret;
124}
125EXPORT_SYMBOL(ccwgroup_set_offline);
126
127static ssize_t ccwgroup_online_store(struct device *dev,
128				     struct device_attribute *attr,
129				     const char *buf, size_t count)
130{
131	struct ccwgroup_device *gdev = to_ccwgroupdev(dev);
132	unsigned long value;
133	int ret;
134
135	device_lock(dev);
136	if (!dev->driver) {
137		ret = -EINVAL;
138		goto out;
139	}
140
141	ret = kstrtoul(buf, 0, &value);
142	if (ret)
143		goto out;
144
145	if (value == 1)
146		ret = ccwgroup_set_online(gdev);
147	else if (value == 0)
148		ret = ccwgroup_set_offline(gdev);
149	else
150		ret = -EINVAL;
151out:
152	device_unlock(dev);
153	return (ret == 0) ? count : ret;
154}
155
156static ssize_t ccwgroup_online_show(struct device *dev,
157				    struct device_attribute *attr,
158				    char *buf)
159{
160	struct ccwgroup_device *gdev = to_ccwgroupdev(dev);
161	int online;
162
163	online = (gdev->state == CCWGROUP_ONLINE) ? 1 : 0;
164
165	return scnprintf(buf, PAGE_SIZE, "%d\n", online);
166}
167
168/*
169 * Provide an 'ungroup' attribute so the user can remove group devices no
170 * longer needed or accidentially created. Saves memory :)
171 */
172static void ccwgroup_ungroup(struct ccwgroup_device *gdev)
173{
174	mutex_lock(&gdev->reg_mutex);
175	if (device_is_registered(&gdev->dev)) {
176		__ccwgroup_remove_symlinks(gdev);
177		device_unregister(&gdev->dev);
178		__ccwgroup_remove_cdev_refs(gdev);
179	}
180	mutex_unlock(&gdev->reg_mutex);
181}
182
183static ssize_t ccwgroup_ungroup_store(struct device *dev,
184				      struct device_attribute *attr,
185				      const char *buf, size_t count)
186{
187	struct ccwgroup_device *gdev = to_ccwgroupdev(dev);
188	int rc = 0;
189
190	/* Prevent concurrent online/offline processing and ungrouping. */
191	if (atomic_cmpxchg(&gdev->onoff, 0, 1) != 0)
192		return -EAGAIN;
193	if (gdev->state != CCWGROUP_OFFLINE) {
194		rc = -EINVAL;
195		goto out;
196	}
197
198	if (device_remove_file_self(dev, attr))
199		ccwgroup_ungroup(gdev);
200	else
201		rc = -ENODEV;
202out:
203	if (rc) {
204		/* Release onoff "lock" when ungrouping failed. */
205		atomic_set(&gdev->onoff, 0);
206		return rc;
207	}
208	return count;
209}
210static DEVICE_ATTR(ungroup, 0200, NULL, ccwgroup_ungroup_store);
211static DEVICE_ATTR(online, 0644, ccwgroup_online_show, ccwgroup_online_store);
212
213static struct attribute *ccwgroup_attrs[] = {
214	&dev_attr_online.attr,
215	&dev_attr_ungroup.attr,
216	NULL,
217};
218static struct attribute_group ccwgroup_attr_group = {
219	.attrs = ccwgroup_attrs,
220};
221static const struct attribute_group *ccwgroup_attr_groups[] = {
222	&ccwgroup_attr_group,
223	NULL,
224};
225
226static void ccwgroup_ungroup_workfn(struct work_struct *work)
227{
228	struct ccwgroup_device *gdev =
229		container_of(work, struct ccwgroup_device, ungroup_work);
230
231	ccwgroup_ungroup(gdev);
232	put_device(&gdev->dev);
233}
234
235static void ccwgroup_release(struct device *dev)
236{
237	kfree(to_ccwgroupdev(dev));
238}
239
240static int __ccwgroup_create_symlinks(struct ccwgroup_device *gdev)
241{
242	char str[16];
243	int i, rc;
244
245	for (i = 0; i < gdev->count; i++) {
246		rc = sysfs_create_link(&gdev->cdev[i]->dev.kobj,
247				       &gdev->dev.kobj, "group_device");
248		if (rc) {
249			for (--i; i >= 0; i--)
250				sysfs_remove_link(&gdev->cdev[i]->dev.kobj,
251						  "group_device");
252			return rc;
253		}
254	}
255	for (i = 0; i < gdev->count; i++) {
256		sprintf(str, "cdev%d", i);
257		rc = sysfs_create_link(&gdev->dev.kobj,
258				       &gdev->cdev[i]->dev.kobj, str);
259		if (rc) {
260			for (--i; i >= 0; i--) {
261				sprintf(str, "cdev%d", i);
262				sysfs_remove_link(&gdev->dev.kobj, str);
263			}
264			for (i = 0; i < gdev->count; i++)
265				sysfs_remove_link(&gdev->cdev[i]->dev.kobj,
266						  "group_device");
267			return rc;
268		}
269	}
270	return 0;
271}
272
273static int __get_next_id(const char **buf, struct ccw_dev_id *id)
274{
275	unsigned int cssid, ssid, devno;
276	int ret = 0, len;
277	char *start, *end;
278
279	start = (char *)*buf;
280	end = strchr(start, ',');
281	if (!end) {
282		/* Last entry. Strip trailing newline, if applicable. */
283		end = strchr(start, '\n');
284		if (end)
285			*end = '\0';
286		len = strlen(start) + 1;
287	} else {
288		len = end - start + 1;
289		end++;
290	}
291	if (len <= CCW_BUS_ID_SIZE) {
292		if (sscanf(start, "%2x.%1x.%04x", &cssid, &ssid, &devno) != 3)
293			ret = -EINVAL;
294	} else
295		ret = -EINVAL;
296
297	if (!ret) {
298		id->ssid = ssid;
299		id->devno = devno;
300	}
301	*buf = end;
302	return ret;
303}
304
305/**
306 * ccwgroup_create_dev() - create and register a ccw group device
307 * @parent: parent device for the new device
308 * @gdrv: driver for the new group device
309 * @num_devices: number of slave devices
310 * @buf: buffer containing comma separated bus ids of slave devices
311 *
312 * Create and register a new ccw group device as a child of @parent. Slave
313 * devices are obtained from the list of bus ids given in @buf.
314 * Returns:
315 *  %0 on success and an error code on failure.
316 * Context:
317 *  non-atomic
318 */
319int ccwgroup_create_dev(struct device *parent, struct ccwgroup_driver *gdrv,
320			int num_devices, const char *buf)
321{
322	struct ccwgroup_device *gdev;
323	struct ccw_dev_id dev_id;
324	int rc, i;
325
326	if (num_devices < 1)
327		return -EINVAL;
328
329	gdev = kzalloc(struct_size(gdev, cdev, num_devices), GFP_KERNEL);
330	if (!gdev)
331		return -ENOMEM;
332
333	atomic_set(&gdev->onoff, 0);
334	mutex_init(&gdev->reg_mutex);
335	mutex_lock(&gdev->reg_mutex);
336	INIT_WORK(&gdev->ungroup_work, ccwgroup_ungroup_workfn);
337	gdev->count = num_devices;
338	gdev->dev.bus = &ccwgroup_bus_type;
339	gdev->dev.parent = parent;
340	gdev->dev.release = ccwgroup_release;
341	device_initialize(&gdev->dev);
342
343	for (i = 0; i < num_devices && buf; i++) {
344		rc = __get_next_id(&buf, &dev_id);
345		if (rc != 0)
346			goto error;
347		gdev->cdev[i] = get_ccwdev_by_dev_id(&dev_id);
348		/*
349		 * All devices have to be of the same type in
350		 * order to be grouped.
351		 */
352		if (!gdev->cdev[i] || !gdev->cdev[i]->drv ||
353		    gdev->cdev[i]->drv != gdev->cdev[0]->drv ||
354		    gdev->cdev[i]->id.driver_info !=
355		    gdev->cdev[0]->id.driver_info) {
356			rc = -EINVAL;
357			goto error;
358		}
359		/* Don't allow a device to belong to more than one group. */
360		spin_lock_irq(gdev->cdev[i]->ccwlock);
361		if (dev_get_drvdata(&gdev->cdev[i]->dev)) {
362			spin_unlock_irq(gdev->cdev[i]->ccwlock);
363			rc = -EINVAL;
364			goto error;
365		}
366		dev_set_drvdata(&gdev->cdev[i]->dev, gdev);
367		spin_unlock_irq(gdev->cdev[i]->ccwlock);
368	}
369	/* Check for sufficient number of bus ids. */
370	if (i < num_devices) {
371		rc = -EINVAL;
372		goto error;
373	}
374	/* Check for trailing stuff. */
375	if (i == num_devices && buf && strlen(buf) > 0) {
376		rc = -EINVAL;
377		goto error;
378	}
379	/* Check if the devices are bound to the required ccw driver. */
380	if (gdrv && gdrv->ccw_driver &&
381	    gdev->cdev[0]->drv != gdrv->ccw_driver) {
382		rc = -EINVAL;
383		goto error;
384	}
385
386	dev_set_name(&gdev->dev, "%s", dev_name(&gdev->cdev[0]->dev));
387	gdev->dev.groups = ccwgroup_attr_groups;
388
389	if (gdrv) {
390		gdev->dev.driver = &gdrv->driver;
391		rc = gdrv->setup ? gdrv->setup(gdev) : 0;
392		if (rc)
393			goto error;
394	}
395	rc = device_add(&gdev->dev);
396	if (rc)
397		goto error;
398	rc = __ccwgroup_create_symlinks(gdev);
399	if (rc) {
400		device_del(&gdev->dev);
401		goto error;
402	}
403	mutex_unlock(&gdev->reg_mutex);
404	return 0;
405error:
406	for (i = 0; i < num_devices; i++)
407		if (gdev->cdev[i]) {
408			spin_lock_irq(gdev->cdev[i]->ccwlock);
409			if (dev_get_drvdata(&gdev->cdev[i]->dev) == gdev)
410				dev_set_drvdata(&gdev->cdev[i]->dev, NULL);
411			spin_unlock_irq(gdev->cdev[i]->ccwlock);
412			put_device(&gdev->cdev[i]->dev);
413			gdev->cdev[i] = NULL;
414		}
415	mutex_unlock(&gdev->reg_mutex);
416	put_device(&gdev->dev);
417	return rc;
418}
419EXPORT_SYMBOL(ccwgroup_create_dev);
420
421static int ccwgroup_notifier(struct notifier_block *nb, unsigned long action,
422			     void *data)
423{
424	struct ccwgroup_device *gdev = to_ccwgroupdev(data);
425
426	if (action == BUS_NOTIFY_UNBIND_DRIVER) {
427		get_device(&gdev->dev);
428		schedule_work(&gdev->ungroup_work);
429	}
430
431	return NOTIFY_OK;
432}
433
434static struct notifier_block ccwgroup_nb = {
435	.notifier_call = ccwgroup_notifier
436};
437
438static int __init init_ccwgroup(void)
439{
440	int ret;
441
442	ret = bus_register(&ccwgroup_bus_type);
443	if (ret)
444		return ret;
445
446	ret = bus_register_notifier(&ccwgroup_bus_type, &ccwgroup_nb);
447	if (ret)
448		bus_unregister(&ccwgroup_bus_type);
449
450	return ret;
451}
452
453static void __exit cleanup_ccwgroup(void)
454{
455	bus_unregister_notifier(&ccwgroup_bus_type, &ccwgroup_nb);
456	bus_unregister(&ccwgroup_bus_type);
457}
458
459module_init(init_ccwgroup);
460module_exit(cleanup_ccwgroup);
461
462/************************** driver stuff ******************************/
463
464static int ccwgroup_remove(struct device *dev)
465{
466	struct ccwgroup_device *gdev = to_ccwgroupdev(dev);
467	struct ccwgroup_driver *gdrv = to_ccwgroupdrv(dev->driver);
468
469	if (!dev->driver)
470		return 0;
471	if (gdrv->remove)
472		gdrv->remove(gdev);
473
474	return 0;
475}
476
477static void ccwgroup_shutdown(struct device *dev)
478{
479	struct ccwgroup_device *gdev = to_ccwgroupdev(dev);
480	struct ccwgroup_driver *gdrv = to_ccwgroupdrv(dev->driver);
481
482	if (!dev->driver)
483		return;
484	if (gdrv->shutdown)
485		gdrv->shutdown(gdev);
486}
487
488static struct bus_type ccwgroup_bus_type = {
489	.name   = "ccwgroup",
490	.remove = ccwgroup_remove,
491	.shutdown = ccwgroup_shutdown,
492};
493
494bool dev_is_ccwgroup(struct device *dev)
495{
496	return dev->bus == &ccwgroup_bus_type;
497}
498EXPORT_SYMBOL(dev_is_ccwgroup);
499
500/**
501 * ccwgroup_driver_register() - register a ccw group driver
502 * @cdriver: driver to be registered
503 *
504 * This function is mainly a wrapper around driver_register().
505 */
506int ccwgroup_driver_register(struct ccwgroup_driver *cdriver)
507{
508	/* register our new driver with the core */
509	cdriver->driver.bus = &ccwgroup_bus_type;
510
511	return driver_register(&cdriver->driver);
512}
513EXPORT_SYMBOL(ccwgroup_driver_register);
514
515/**
516 * ccwgroup_driver_unregister() - deregister a ccw group driver
517 * @cdriver: driver to be deregistered
518 *
519 * This function is mainly a wrapper around driver_unregister().
520 */
521void ccwgroup_driver_unregister(struct ccwgroup_driver *cdriver)
522{
523	struct device *dev;
524
525	/* We don't want ccwgroup devices to live longer than their driver. */
526	while ((dev = driver_find_next_device(&cdriver->driver, NULL))) {
527		struct ccwgroup_device *gdev = to_ccwgroupdev(dev);
528
529		ccwgroup_ungroup(gdev);
530		put_device(dev);
531	}
532	driver_unregister(&cdriver->driver);
533}
534EXPORT_SYMBOL(ccwgroup_driver_unregister);
535
536/**
537 * get_ccwgroupdev_by_busid() - obtain device from a bus id
538 * @gdrv: driver the device is owned by
539 * @bus_id: bus id of the device to be searched
540 *
541 * This function searches all devices owned by @gdrv for a device with a bus
542 * id matching @bus_id.
543 * Returns:
544 *  If a match is found, its reference count of the found device is increased
545 *  and it is returned; else %NULL is returned.
546 */
547struct ccwgroup_device *get_ccwgroupdev_by_busid(struct ccwgroup_driver *gdrv,
548						 char *bus_id)
549{
550	struct device *dev;
551
552	dev = driver_find_device_by_name(&gdrv->driver, bus_id);
553
554	return dev ? to_ccwgroupdev(dev) : NULL;
555}
556EXPORT_SYMBOL_GPL(get_ccwgroupdev_by_busid);
557
558/**
559 * ccwgroup_probe_ccwdev() - probe function for slave devices
560 * @cdev: ccw device to be probed
561 *
562 * This is a dummy probe function for ccw devices that are slave devices in
563 * a ccw group device.
564 * Returns:
565 *  always %0
566 */
567int ccwgroup_probe_ccwdev(struct ccw_device *cdev)
568{
569	return 0;
570}
571EXPORT_SYMBOL(ccwgroup_probe_ccwdev);
572
573/**
574 * ccwgroup_remove_ccwdev() - remove function for slave devices
575 * @cdev: ccw device to be removed
576 *
577 * This is a remove function for ccw devices that are slave devices in a ccw
578 * group device. It sets the ccw device offline and also deregisters the
579 * embedding ccw group device.
580 */
581void ccwgroup_remove_ccwdev(struct ccw_device *cdev)
582{
583	struct ccwgroup_device *gdev;
584
585	/* Ignore offlining errors, device is gone anyway. */
586	ccw_device_set_offline(cdev);
587	/* If one of its devices is gone, the whole group is done for. */
588	spin_lock_irq(cdev->ccwlock);
589	gdev = dev_get_drvdata(&cdev->dev);
590	if (!gdev) {
591		spin_unlock_irq(cdev->ccwlock);
592		return;
593	}
594	/* Get ccwgroup device reference for local processing. */
595	get_device(&gdev->dev);
596	spin_unlock_irq(cdev->ccwlock);
597	/* Unregister group device. */
598	ccwgroup_ungroup(gdev);
599	/* Release ccwgroup device reference for local processing. */
600	put_device(&gdev->dev);
601}
602EXPORT_SYMBOL(ccwgroup_remove_ccwdev);
603MODULE_LICENSE("GPL");
604