ccwgroup.c

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