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 
34 static struct bus_type ccwgroup_bus_type;
35 
__ccwgroup_remove_symlinks(struct ccwgroup_device * gdev)36 static 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  */
ccwgroup_set_online(struct ccwgroup_device * gdev)56 int 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;
71 out:
72 	atomic_set(&gdev->onoff, 0);
73 	return ret;
74 }
75 EXPORT_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  */
ccwgroup_set_offline(struct ccwgroup_device * gdev,bool call_gdrv)86 int 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 
104 offline:
105 	gdev->state = CCWGROUP_OFFLINE;
106 out:
107 	atomic_set(&gdev->onoff, 0);
108 	return ret;
109 }
110 EXPORT_SYMBOL(ccwgroup_set_offline);
111 
ccwgroup_online_store(struct device * dev,struct device_attribute * attr,const char * buf,size_t count)112 static 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;
136 out:
137 	device_unlock(dev);
138 	return (ret == 0) ? count : ret;
139 }
140 
ccwgroup_online_show(struct device * dev,struct device_attribute * attr,char * buf)141 static 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 accidentially created. Saves memory :)
156  */
ccwgroup_ungroup(struct ccwgroup_device * gdev)157 static 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 
ccwgroup_ungroup_store(struct device * dev,struct device_attribute * attr,const char * buf,size_t count)167 static 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;
186 out:
187 	if (rc) {
188 		/* Release onoff "lock" when ungrouping failed. */
189 		atomic_set(&gdev->onoff, 0);
190 		return rc;
191 	}
192 	return count;
193 }
194 static DEVICE_ATTR(ungroup, 0200, NULL, ccwgroup_ungroup_store);
195 static DEVICE_ATTR(online, 0644, ccwgroup_online_show, ccwgroup_online_store);
196 
197 static struct attribute *ccwgroup_dev_attrs[] = {
198 	&dev_attr_online.attr,
199 	&dev_attr_ungroup.attr,
200 	NULL,
201 };
202 ATTRIBUTE_GROUPS(ccwgroup_dev);
203 
ccwgroup_ungroup_workfn(struct work_struct * work)204 static 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 
ccwgroup_release(struct device * dev)213 static 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 
__ccwgroup_create_symlinks(struct ccwgroup_device * gdev)234 static 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 			for (--i; i >= 0; 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 			for (--i; i >= 0; 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 
__get_next_id(const char ** buf,struct ccw_dev_id * id)267 static 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  */
ccwgroup_create_dev(struct device * parent,struct ccwgroup_driver * gdrv,int num_devices,const char * buf)313 int 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;
398 error:
399 	mutex_unlock(&gdev->reg_mutex);
400 	put_device(&gdev->dev);
401 	return rc;
402 }
403 EXPORT_SYMBOL(ccwgroup_create_dev);
404 
ccwgroup_notifier(struct notifier_block * nb,unsigned long action,void * data)405 static 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 
418 static struct notifier_block ccwgroup_nb = {
419 	.notifier_call = ccwgroup_notifier
420 };
421 
init_ccwgroup(void)422 static 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 
cleanup_ccwgroup(void)437 static void __exit cleanup_ccwgroup(void)
438 {
439 	bus_unregister_notifier(&ccwgroup_bus_type, &ccwgroup_nb);
440 	bus_unregister(&ccwgroup_bus_type);
441 }
442 
443 module_init(init_ccwgroup);
444 module_exit(cleanup_ccwgroup);
445 
446 /************************** driver stuff ******************************/
447 
ccwgroup_remove(struct device * dev)448 static 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 
ccwgroup_shutdown(struct device * dev)457 static 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 
468 static 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 
dev_is_ccwgroup(struct device * dev)475 bool dev_is_ccwgroup(struct device *dev)
476 {
477 	return dev->bus == &ccwgroup_bus_type;
478 }
479 EXPORT_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  */
ccwgroup_driver_register(struct ccwgroup_driver * cdriver)487 int 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 }
494 EXPORT_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  */
ccwgroup_driver_unregister(struct ccwgroup_driver * cdriver)502 void ccwgroup_driver_unregister(struct ccwgroup_driver *cdriver)
503 {
504 	driver_unregister(&cdriver->driver);
505 }
506 EXPORT_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  */
ccwgroup_probe_ccwdev(struct ccw_device * cdev)517 int ccwgroup_probe_ccwdev(struct ccw_device *cdev)
518 {
519 	return 0;
520 }
521 EXPORT_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  */
ccwgroup_remove_ccwdev(struct ccw_device * cdev)531 void 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 }
552 EXPORT_SYMBOL(ccwgroup_remove_ccwdev);
553 MODULE_LICENSE("GPL");
554