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